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  • 1.
    Aboulfadl, Hisham
    et al.
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsen, Jes K
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Microstructural Characterization of Sulfurization Effects in Cu(In,Ga)Se-2 Thin Film Solar Cells2019In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, no 2, p. 532-538Article in journal (Refereed)
    Abstract [en]

    Surface sulfurization of Cu(In,Ga)Se-2 (CIGSe) absorbers is a commonly applied technique to improve the conversion efficiency of the corresponding solar cells, via increasing the bandgap towards the heterojunction. However, the resulting device performance is understood to be highly dependent on the thermodynamic stability of the chalcogenide structure at the upper region of the absorber. The present investigation provides a high-resolution chemical analysis, using energy dispersive X-ray spectrometry and laser-pulsed atom probe tomography, to determine the sulfur incorporation and chemical re-distribution in the absorber material. The post-sulfurization treatment was performed by exposing the CIGSe surface to elemental sulfur vapor for 20 min at 500 degrees C. Two distinct sulfur-rich phases were found at the surface of the absorber exhibiting a layered structure showing In-rich and Ga-rich zones, respectively. Furthermore, sulfur atoms were found to segregate at the absorber grain boundaries showing concentrations up to similar to 7 at% with traces of diffusion outwards into the grain interior.

  • 2.
    Aboulfadl, Hisham
    et al.
    Chalmers Univ Technol, Dept Phys, Div Microstruct Phys, S-41296 Gothenburg, Sweden..
    Sopiha, Kostiantyn
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Larsen, Jes K
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Scragg, Jonathan J.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Persson, Clas
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, N-0316 Oslo, Norway.;KTH Royal Inst Technol, Dept Mat Sci & Engn, Div Appl Mat Phys, S-10044 Stockholm, Sweden..
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, Div Microstruct Phys, S-41296 Gothenburg, Sweden..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Alkali Dispersion in (Ag,Cu)(In,Ga)Se-2 Thin Film Solar Cells-Insight from Theory and Experiment2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 6, p. 7188-7199Article in journal (Refereed)
    Abstract [en]

    Silver alloying of Cu(In,Ga)Se-2 absorbers for thin film photovoltaics offers improvements in open-circuit voltage, especially when combined with optimal alkali-treatments and certain Ga concentrations. The relationship between alkali distribution in the absorber and Ag alloying is investigated here, combining experimental and theoretical studies. Atom probe tomography analysis is implemented to quantify the local composition in grain interiors and at grain boundaries. The Na concentration in the bulk increases up to similar to 60 ppm for [Ag]/([Ag] + [Cu]) = 0.2 compared to similar to 20 ppm for films without Ag and up to similar to 200 ppm for [Ag]/([Ag] + [Cu]) = 1.0. First-principles calculations were employed to evaluate the formation energies of alkali-on-group-I defects (where group-I refers to Ag and Cu) in (Ag,Cu)(In,Ga)Se-2 as a function of the Ag and Ga contents. The computational results demonstrate strong agreement with the nanoscale analysis results, revealing a clear trend of increased alkali bulk solubility with the Ag concentration. The present study, therefore, provides a more nuanced understanding of the role of Ag in the enhanced performance of the respective photovoltaic devices.

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  • 3.
    Alberto, H. V.
    et al.
    Univ Coimbra, Dept Phys, CFisUC, R Larga, P-3004516 Coimbra, Portugal..
    Vilão, R. C.
    Univ Coimbra, Dept Phys, CFisUC, R Larga, P-3004516 Coimbra, Portugal..
    Ribeiro, E. F. M.
    Univ Coimbra, Dept Phys, CFisUC, R Larga, P-3004516 Coimbra, Portugal..
    Gil, J. M.
    Univ Coimbra, Dept Phys, CFisUC, R Larga, P-3004516 Coimbra, Portugal..
    Curado, M. A.
    Univ Coimbra, Dept Phys, CFisUC, R Larga, P-3004516 Coimbra, Portugal.;Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal..
    Teixeira, J. P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, i3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;CIETI, Dept Fis, Inst Sup Eng Porto, Inst Pol Porto, P-4200072 Porto, Portugal..
    Fernandes, P. A.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, i3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;CIETI, Dept Fis, Inst Sup Eng Porto, Inst Pol Porto, P-4200072 Porto, Portugal..
    Cunha, J. M. V.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, i3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal..
    Salomé, P. M. P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Martins, M. I.
    Swiss Fed Inst Technol, Adv Power Semicond Lab, CH-8092 Zurich, Switzerland.;Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Prokscha, T.
    Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Salman, Z.
    Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Weidinger, A.
    Helmholtz Zentrum Berlin Mat & Energie, Dept ASPIN, D-14109 Berlin, Germany..
    Low energy muon study of the p-n interface in chalcopyrite solar cells2023In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 2462, article id 012047Article in journal (Refereed)
    Abstract [en]

    The slow muon technique was used to study the p-n junction of chalcopyrite solar cells. A defect layer near the interface was identified and the passivation of the defects by buffer layers was studied. Several cover layers on top of the chalcopyrite Cu(In,Ga)Se2 (CIGS) semiconductor absorber were investigated in this work, namely CdS, ZnSnO, Al2O3 and SiO2. Quantitative results were obtained: The defect layer extends about 50 nm into the CIGS absorber, the relevant disturbance is strain in the lattice, and CdS provides the best passivation, oxides have a minor effect. In the present contribution, specific aspects of the low-energy muon technique in connection with this research are discussed.

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  • 4.
    Alberto, Helena, V
    et al.
    Univ Coimbra, Dept Phys, CFisUC, P-3004516 Coimbra, Portugal..
    Vilao, Rui C.
    Univ Coimbra, Dept Phys, CFisUC, P-3004516 Coimbra, Portugal..
    Ribeiro, Eduardo F. M.
    Univ Coimbra, Dept Phys, CFisUC, P-3004516 Coimbra, Portugal..
    Gil, Joao M.
    Univ Coimbra, Dept Phys, CFisUC, P-3004516 Coimbra, Portugal..
    Curado, Marco A.
    Univ Coimbra, Dept Phys, CFisUC, P-3004516 Coimbra, Portugal.;Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal..
    Teixeira, Jennifer P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Inst Pol Porto, Inst Sup Eng Porto, Dept Fis, CIETI, P-4200072 Porto, Portugal..
    Fernandes, Paulo A.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Inst Pol Porto, Inst Sup Eng Porto, Dept Fis, CIETI, P-4200072 Porto, Portugal..
    Cunha, Jose M., V
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal..
    Salome, Pedro M. P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Martins, Maria, I
    Swiss Fed Inst Technol, Adv Power Semicond Lab, CH-8092 Zurich, Switzerland.;Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Prokscha, Thomas
    Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Salman, Zaher
    Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland..
    Weidinger, Alois
    Helmholtz Zentrum Berlin Mat & Energie, Dept ASPIN, D-14109 Berlin, Germany..
    Characterization of the Interfacial Defect Layer in Chalcopyrite Solar Cells by Depth-Resolved Muon Spin Spectroscopy2022In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 9, no 19, article id 2200374Article in journal (Refereed)
    Abstract [en]

    As devices become smaller and more complex, the interfaces between adjacent materials become increasingly important and are often critical to device performance. An important research goal is to improve the interface between the absorber and the window layer by inserting buffer layers to adjust the transition. Depth-resolved studies are key for a fundamental understanding of the interface. In the present experiment, the interface between the chalcopyrite Cu(In,Ga)Se-2 absorber and various buffer layers are investigated using low-energy muon spin rotation (mu SR) spectroscopy. Depth resolution in the nm range is achieved by implanting the muons with different energies so that they stop at different depths in the sample. Near the interface, a region about 50 nm wide is detected where the lattice is more distorted than further inside the absorber. The distortion is attributed to the long-range strain field caused by defects. These measurements allow a quantification of the corresponding passivation effect of the buffer layer. Bath-deposited cadmium sulfide provides the best defect passivation in the near interface region, in contrast to the dry-deposited oxides, which have a much smaller effect. The experiment demonstrates the great potential of low energy mu SR spectroscopy for microscopic interfacial studies of multilayer systems.

  • 5.
    Anacleto, Pedro
    et al.
    INL Int Iberian Nanotechnol Lab, Av Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Hägglund, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Kovacic, Milan
    Fac Elect Engn, Trzaska Cesta 25, SI-1000 Ljubljana, Slovenia..
    Krc, Janez
    Fac Elect Engn, Trzaska Cesta 25, SI-1000 Ljubljana, Slovenia..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Sadewasser, Sascha
    INL Int Iberian Nanotechnol Lab, Av Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Precisely nanostructured HfO2 rear passivation layers for ultra-thin Cu(In,Ga)Se-22022In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 30, no 11, p. 1289-1297Article in journal (Refereed)
    Abstract [en]

    The quest for material-efficient Cu(In,Ga)Se-2 (CIGS) solar cells encourages the development of ultra-thin absorbers. Their use reduces material consumption and energy usage during production by increasing the throughput. Thereby, both the bill of materials as well as the energy and capital costs are reduced. However, because thin absorbers are prone to increase back contact recombination, back surface passivation schemes are necessary to reach a similar or higher conversion efficiency than for absorbers with conventional thickness. Here, we investigate nanostructured hafnium oxide (HfO2) rear passivation layers for ultra-thin CIGS solar cells. We fabricate regular arrays of point contacts with 200 nm diameter through HfO2 layers with thicknesses between 7 and 40 nm using electron beam lithography and reactive ion etching. The current-voltage curves of solar cells with a 500 nm thick CIGS absorber layer and the nanostructured passivation layer show improved performance concerning V-oc and J(sc) compared to non-passivated reference devices. Furthermore, external quantum efficiency and optical reflection confirm an effective passivation behavior, with an average efficiency increase of up to 1.2% for the cells with the 40 nm thick HfO2 layer. In addition, simulation work shows that even 40 nm thick HfO2 passivation layers have only a minimal effect on the optical properties of ultra-thin CIGS solar cells, and hence, the photocurrent increase verified experimentally stems from electrical improvements caused by the HfO2 layer passivation effect. We also investigate the impact of ultra-thin (0.3, 0.6, 1.3, and 2.5 nm) non-patterned HfO2 passivation layers on the same type of solar cells. However, these results showed no improvement in solar cell performance, despite an increase in the current density with layer thickness.

  • 6.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Atak, Gamze
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Hacettepe Univ, Phys Engn Dept, TR-06800 Ankara, Turkey..
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Electrochromic solar water splitting using a cathodic WO3 electrocatalyst2021In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 81, article id 105620Article in journal (Refereed)
    Abstract [en]

    Solar-driven water splitting is an emerging technology with high potential to generate fuel cleanly and sustainably. In this work, we show that WO3 can be used as a cathodic electrocatalyst in combination with (Ag,Cu) InGaSe2 solar cell modules to produce hydrogen and provide electrochromic functionality to water splitting devices. This electrochromic effect can be used to monitor the charge state or performance of the catalyst for process control or for controlling the temperature and absorbed heat due to tunable optical modulation of the electrocatalyst. WO3 films coated on Ni foam, using a wide range of different sputtering conditions, were investigated as cathodic electrocatalysts for the water splitting reaction. The solar-to-hydrogen (STH) efficiency of solar-driven water electrolysis was extracted using (Ag,Cu)InGaSe2 solar cell modules with a cell band gap varied in between 1.15 and 1.25 eV with WO3 on Ni foam-based electrolyzers and yielded up to 13% STH efficiency. Electrochromic properties during water electrolysis were characterized for the WO3 films on transparent substrate (indium tin oxide). Transmittance varied between 10% and 78% and the coloration efficiency at a wavelength of 528 nm and the overpotential of 400 mV was 40 cm(2) C-1. Hydrogen ion consumption in ion intercalation for electrochromic and hydrogen gas production for water electrolysis processes was discussed.

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  • 7.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Solibro research AB.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. tomas.edvinsson@angstrom.uu.se.
    Optimum Band Gap Energy of ((Ag),Cu)(InGa)Se2 Materials for Combination with NiMo–NiO Catalysts for Thermally Integrated Solar-Driven Water Splitting Applications2019In: Energies, E-ISSN 1996-1073, Vol. 12, article id 4064Article in journal (Refereed)
    Abstract [en]

    Solar-driven water splitting is considered one of the promising future routes to generate fuel in a sustainable way. A carbon-free solar fuel, molecular hydrogen, can here be produced along two different but intimately related routes, photoelectrochemical (PEC) water splitting or photovoltaic electrolysis (PV-electrolysis), where the latter builds on well-established solar cell and electrolysis materials with high efficiency. The PV-electrolysis approach is also possible to construct from an integrated PEC/PV-system avoiding dc-dc converters and enabling heat exchange between the PV and electrolyzer part, to a conventionally wired PV-electrolysis system. In either case, the operating voltage at a certain current needs to be matched with the catalyst system in the electrolysis part. Here, we investigate ((Ag),Cu)(In,Ga)Se-2 ((A)CIGS)-materials with varying Ga-content modules for combination with NiMo-NiO catalysts in alkaline water splitting. The use of (A)CIGS is attractive because of the low cost-to-performance ratio and the possibility to optimize the performance of the system by tuning the band gap of (A)CIGS in contrast to Si technology. The band gap tuning is possible by changing the Ga/(Ga + In) ratio. Optoelectronic properties of the (A)CIGS materials with Ga/(Ga + In) ratios between 0.23 and 0.47 and the voltage and power output from the resulting water splitting modules are reported. Electrolysis is quantified at temperatures between 25 and 60 degrees C, an interval obtainable by varying the thermal heat exchange form a 1-sun illuminated PV module and an electrolyte system. The band gaps of the (A)CIGS thin films were between 1.08 to 1.25 eV and the three-cell module power conversion efficiencies (PCE) ranged from 16.44% with 1.08 eV band gap and 19.04% with 1.17 eV band gap. The highest solar-to-hydrogen (STH) efficiency was 13.33% for the (A)CIGS-NiMo-NiO system with 17.97% module efficiency and electrolysis at 60 degrees C compared to a STH efficiency of 12.98% at 25 degrees C. The increase in STH efficiency with increasing temperature was more notable for lower band gaps as these are closer to the overpotential threshold for performing efficient solar-driven catalysis, while only a modest improvement can be obtained by utilizing thermal exchange for a band gap matched PV-catalysts system. The results show that usage of cost-effective and stable thin film PV materials and earth abundant catalysts can provide STH efficiencies beyond 13% even with PV modules with modest efficiency.

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  • 8.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Malm, U.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Neretnieks, P.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Glüsen, A.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Müller, M.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Welter, K.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Haas, S.
    Forschungszentrum Julich, Wilhelm Johnen Str, D-52428 Julich, Germany..
    Calnan, S.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, PVcomB, Schwarzschildstr 3, D-12489 Berlin, Germany..
    Canino, A.
    ENEL Greenpower, Contrada Blocco Torrazze, I-95121 Catania, Italy..
    Milazzo, R. G.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Privitera, S. M. S.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Lombardo, S. A.
    CNR, IMM, Ottava Str 5, I-95121 Catania, Italy..
    Stolt, L.
    Solibro Res AB, Vallvagen 5, S-75651 Uppsala, Sweden..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    The climatic response of thermally integrated photovoltaic-electrolysis water splitting using Si and CIGS combined with acidic and alkaline electrolysis2020In: Sustainable Energy & Fuels, E-ISSN 2398-4902, Vol. 4, no 12, p. 6011-6022Article in journal (Refereed)
    Abstract [en]

    The Horizon 2020 project PECSYS aims to build a large area demonstrator for hydrogen production from solar energy via integrated photovoltaic (PV) and electrolysis systems of different types. In this study, Si- and CIGS-based photovoltaics are developed together with three different electrolyzer systems for use in the corresponding integrated devices. The systems are experimentally evaluated and a general model is developed to investigate the hydrogen yield under real climatic conditions for various thin film and silicon PV technologies and electrolyser combinations. PV characteristics using a Si heterojunction (SHJ), thin film CuInxGa1-xSe2, crystalline Si with passivated emitter rear totally diffused and thin film Si are used together with temperature dependent catalyst load curves from both acidic and alkaline approaches. Electrolysis data were collected from (i) a Pt-IrO2-based acidic electrolysis system, and (ii) NiMoW-NiO-based and (iii) Pt-Ni foam-based alkaline electrolysis systems. The calculations were performed for mid-European climate data from Julich, Germany, which will be the installation site. The best systems show an electricity-to-hydrogen conversion efficiency of 74% and over 12% solar-to-hydrogen (STH) efficiencies using both acidic and alkaline approaches and are validated with a smaller lab scale prototype. The results show that the lower power delivered by all the PV technologies under low irradiation is balanced by the lower demand for overpotentials for all the electrolysis approaches at these currents, with more or less retained STH efficiency over the full year if the catalyst area is the same as the PV area for the alkaline approach. The total yield of hydrogen, however, follows the irradiance, where a yearly hydrogen production of over 35 kg can be achieved for a 10 m(2) integrated PV-electrolysis system for several of the PV and electrolyser combinations that also allow a significant (100-fold) reduction in necessary electrolyser area for the acidic approach. Measuring the catalyst systems under intermittent and ramping conditions with different temperatures, a 5% lowering of the yearly hydrogen yield is extracted for some of the catalyst systems while the Pt-Ni foam-based alkaline system showed unaffected or even slightly increased yearly yield under the same conditions.

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  • 9.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Oscarsson, Johan
    Solibro Res AB, Vallvägen 5, S-75651 Uppsala, Sweden.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Stolt, Lars
    Solibro Res AB, Vallvägen 5, S-75651 Uppsala, Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    NiMoV and NiO-based catalysts for efficient solar-driven water splitting using thermally integrated photovoltaics in a scalable approach2021In: iScience, E-ISSN 2589-0042 , Vol. 24, no 1, article id 101910Article in journal (Refereed)
    Abstract [en]

    In this work, a trimetallic NiMoV catalyst is developed for the hydrogen evolution reaction and characterized with respect to structure, valence, and elemental distribution. The overpotential to drive a 10 mA cm−2 current density is lowered from 94 to 78 mV versus reversible hydrogen electrode by introducing V into NiMo. A scalable stand-alone system for solar-driven water splitting was examined for a laboratory-scale device with 1.6 cm2 photovoltaic (PV) module area to an up-scaled device with 100 cm2 area. The NiMoV cathodic catalyst is combined with a NiO anode in alkaline electrolyzer unit thermally connected to synthesized (Ag,Cu) (In,Ga)Se2 ((A)CIGS) PV modules. Performance of 3- and 4-cell interconnected PV modules, electrolyzer, and hydrogen production of the PV electrolyzer are examined between 25°C and 50°C. The PV-electrolysis device having a 4-cell (A)CIGS under 100 mW cm−2 illumination and NiMoV-NiO electrolyzer shows 9.1% maximum and 8.5% averaged efficiency for 100 h operation.

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  • 10.
    Bilousov, Oleksandr V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ren, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hägglund, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    ALD of phase controlled tin monosulfide thin films2017Conference paper (Refereed)
    Abstract [en]

    Tin monosulfide (SnS) is a promising semiconductor material for low-cost conversion of solar energy, playing the role of absorber layer in photovoltaic devices. SnS is, due to its high optical damping, also an excellent semiconductor candidate for the realization of ultrathin (nanoscale thickness) plasmonic solar cells [1].

    Here, we present an important step to further control and understand SnS film properties produced using low temperature ALD with Sn(acac)2 and H2S as precursors. We show that the SnS film properties vary over a rather wide range depending on substrate temperature and reaction conditions, and that this is connected to the growth of cubic (π-SnS) and orthorhombic SnS phases. The optical properties of the two polymorphs differ significantly, as demonstrated by spectroscopic ellipsometry [2].

    1. C. Hägglund, G. Zeltzer, R. Ruiz, A. Wangperawong, K. E. Roelofs, S. F. Bent, ACS Photonics 3 (3) (2016) 456–463.

    2. O. V. Bilousov, Y. Ren, T. Törndahl, O. Donzel-Gargand , T. Ericson, C. Platzer-Björkman, M. Edoff, and C. Hägglund, ACS Chemistry of Materials  29 (7) (2017) 2969–2978.

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  • 11.
    Bilousov, Oleksandr V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ren, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ericson, Tove
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hägglund, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Atomic Layer Deposition of Cubic and Orthorhombic Phase Tin Monosulfide2017In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 7, p. 2969-2978Article in journal (Refereed)
    Abstract [en]

    Tin monosulfide (SnS) is a promising light-absorbing material with weak environmental constraints for application in thin film solar cells. In this paper, we present low-temperature atomic layer deposition (ALD) of high-purity SnS of both cubic and orthorhombic phases. Using tin(II) 2,4-pentanedionate [Sn(acac)(2)] and hydrogen sulfide (H2S) as precursors, controlled growth of the two polymorphs is achieved. Quartz crystal microbalance measurements are used to establish saturated conditions and show that the SnS ALD is self-limiting over temperatures from at least 80 to 160 degrees C. In this temperature window, a stable mass gain of 19 ng cm(-2) cycle(-1) is observed. The SnS thin film crystal structure and morphology undergo significant changes depending on the conditions. High-resolution transmission electron microscopy and X-ray diffraction demonstrate that fully saturated growth requires a large H2S dose and results in the cubic phase. Smaller H2S doses and higher temperatures favor the orthorhombic phase. The optical properties of the two polymorphs differ significantly, as demonstrated by spectroscopic ellipsometry. The orthorhombic phase displays a wide (0.3-0.4 eV) Urbach tail in the near-infrared region, ascribed to its nanoscale structural disorder and/or to sulfur vacancy-induced gap states. In contrast, the cubic phase is smooth and void-free and shows a well-defined, direct forbidden-type bandgap of 1.64 eV.

  • 12.
    Bose, Sourav
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Cunha, J. M. V.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Borme, J.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Shariati Nilsson, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Teixeira, J. P.
    Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Gaspar, J.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.
    Leitao, J. P.
    Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fernandes, P. A.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Inst Politecn Porto, Inst Super Engn Porto, Dept Fis, Rua Dr Antonio Bernardino de Almeida 431, P-4200072 Porto, Portugal.
    Salome, P. M. P.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    A morphological and electronic study of ultrathin rear passivated Cu(In,Ga)Se2 solar cells2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 671, p. 77-84Article in journal (Refereed)
    Abstract [en]

    The effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence of growing the CIGS on Al2O3 with point contacts was still unknown from a structural and morphological point of view. Scanning Electron Microscopy, X-ray Diffraction and Raman spectroscopy measurements were performed. These measurements revealed no significant morphological or structural differences in the CIGS layer for the passivated samples compared with reference samples. These results are in agreement with the similar values of carrier density (~8 x 1016 cm-3) and depletion region (~160 nm) extracted using electrical measurements. A detailed comparison between both sample types in terms of current-voltage, external quantum efficiency and photoluminescence measurements show very different optoelectronic behaviour which is indicative of a successful passivation. SCAPS simulations are done to explain the observed results in view of passivation of the rear interface.

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  • 13.
    Böhnke, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Copper indium gallium diselenide thin films for sun angle detectors in space applications2009In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 6, p. 2063-2068Article in journal (Refereed)
    Abstract [en]

    This work reports on processing, analysis and characterization of copper indium gallium diselenide (CIGS)used as a photosensitive layer for sensors such as sun angle detectors in space applications. CIGS-based solarcell devices with different CIGS layer thicknesses and the pn-junction located on the opposite side of theincidence of light were illuminated through their ultra-thin transparent molybdenum back contacts. Theresults from the current density versus voltage and quantum efficiency measurement indicate that the CIGSabsorber layer may not exceed 750 nm at backside illumination, due to the limited CIGS diffusion length.

  • 14.
    Böhnke, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Materialvetenskap.
    Development of a MOEMS sun sensor for space applications2006In: Sensors & Actuators A, Vol. 130-131, p. 28-36Article in journal (Refereed)
  • 15.
    Böhnke, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Kratz, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Hultåker, Annette
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Köhler, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Roos, Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ribbing, Carl-Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Micro Structural Technology.
    Surfaces with high solar reflectance and high thermal emittance on structured silicon for spacecraft thermal control2008In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 30, no 9, p. 1410-1421Article in journal (Refereed)
    Abstract [en]

    Presented here is an examination of unstructured and structured (by anisotropic etching), monocrystalline silicon wafers coated with sputter deposited aluminum and chemical vapor deposited silicon dioxide for high solar reflectance and high thermal emittance, respectively. The topography of the samples was characterized with optical and scanning electron microscopy. Optical properties were examined with reflectance and transmittance spectroscopy, partly by usage of an integrating sphere. The measurement results were used to estimate the equilibrium temperature of the surfaces in space. The suitability of the surfaces with high solar reflectance and high thermal emittance to aid in the thermal control of miniaturized, highly integrated components for space applications is discussed. A silicon dioxide layer on a metal layer results in a slightly lower reflectance when compared to surfaces with only a metal layer, but might be beneficial for miniaturized space components and modules that have to dissipate internally generated heat into open space. Additionally, it is an advantage to microstructure the emitting surface for enhanced radiation of excess heat.

  • 16.
    Calnan, Sonya
    et al.
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Bagacki, Rory
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Bao, Fuxi
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Dorbandt, Iris
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Kemppainen, Erno
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Schary, Christian
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Schlatmann, Rutger
    PVcomB Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Schwarzschildstrasse 3 12489 Berlin Germany.
    Leonardi, Marco
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Lombardo, Salvatore A.
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Milazzo, R. Gabriella
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Privitera, Stefania M. S.
    IMM -Institute for microelectronics and microsystems Consiglio Nazionale Delle Ricerche CNR-IMM Zona Industriale Ottava Strada, 5 95121 Catania Italy.
    Bizzarri, Fabrizio
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Connelli, Carmelo
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Consoli, Daniele
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Gerardi, Cosimo
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Zani, Pierenrico
    Enel Green Power SpA Viale Regina Margherita, 125 00198 Roma Italy.
    Carmo, Marcelo
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Haas, Stefan
    Institute of Energy and Climate Research 5 Photovoltaics (IEK-5) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Lee, Minoh
    Institute of Energy and Climate Research 5 Photovoltaics (IEK-5) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Mueller, Martin
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Zwaygardt, Walter
    Institute of Energy and Climate Research 14 Electrochemical Process Engineering (IEK-14) Forschungszentrum Jülich GmbH Wilhelm-Johnen-Str. 52428 Jülich Germany.
    Oscarsson, Johan
    Solibro Research AB Vallvägen 5 75651 Uppsala Sweden.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. Solibro Research AB Vallvägen 5 75651 Uppsala Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Development of Various Photovoltaic‐Driven Water Electrolysis Technologies for Green Solar Hydrogen Generation2021In: Solar RRL, E-ISSN 2367-198X, Vol. 6, no 5, article id 2100479Article in journal (Refereed)
    Abstract [en]

    Direct solar hydrogen generation via a combination of photovoltaics (PV) and water electrolysis can potentially ensure a sustainable energy supply while minimizing greenhouse emissions. The PECSYS project aims at demonstrating asolar-driven electrochemical hydrogen generation system with an area >10 m2 with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers(ECs) using thin-film silicon, undoped, and silver-doped Cu(In,Ga)Se2 and silicon heterojunction PV combined with alkaline electrolysis to form one unit are developed on a prototype level with solar collection areas in the range from 64 to2600 cm2 with the solar-to-hydrogen (StH) efficiency ranging from 4 to 13%. Electrical direct coupling of PV modules to a proton exchange membrane EC test the effects of bifacially (730 cm2 solar collection area) and to study the long-term operation under outdoor conditions (10 m2 collection area) is also investigated. In both cases, StH efficiencies exceeding 10% can be maintained over the test periods used. All the StH efficiencies reported are based on measured gas outflow using mass flow meters.

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  • 17.
    Campa, A.
    et al.
    University of Ljubljana, Faculty of Electrical Engineering.
    Krc, J.
    University of Ljubljana, Faculty of Electrical Engineering.
    Malmström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Smole, F.
    University of Ljubljana, Faculty of Electrical Engineering.
    Topic, M.
    University of Ljubljana, Faculty of Electrical Engineering.
    The potential of textured front ZnO and flat TCO/metal back contact to improve optical absorption in thin Cu(In,Ga)Se2 solar cells2007In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 15, p. 5968-5972Article in journal (Refereed)
    Abstract [en]

    The role of additionally textured front transparent conductive oxide − TCO (ZnO:Al) and flat TCO/metal contact on optical improvements in thin Cu(In,Ga)Se2 (CIGS) solar cells are investigated by means of numerical simulations. A de-coupled analysis of two effects related to additional texturing of front surface of ZnO:Al TCO − (i) enhancement of light scattering and (ii) decreased total reflectance (antireflective effect) − reveals that the improvements in quantum efficiency, QE, and short-circuit current, JSC, of the solar cell originate from an antireflective effect only. In order to improve optical properties of the back contact the introduction of a TCO layer (undoped ZnO) between CIGS and back metal contact is investigated from the optical point of view. In addition to ZnO/Mo, a highly reflective ZnO/Ag contact (ZnO is also assumed to work as a protection layer for Ag) is also included in simulations. Results show significant increase in reflectance related to introduced ZnO in front of Mo. Drastically increased reflectance is obtained if ZnO/Mo is substituted with ZnO/Ag. The improvements in QE and JSC of a thin CIGS solar cell, related to ZnO/metal contacts are presented.

  • 18. Campa, Andrej
    et al.
    Cernivec, Gregor
    Schleussner, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Krc, Janez
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Topic, Marko
    Potential of optical improvements of the back contact in thin Cu(In,Ga)Se2 solar cells2007In: Proceedings of the 22nd European Photovoltaic Solar Energy Conference, Milano, 2007 : 3CO.9.2, 2007Conference paper (Refereed)
  • 19. Campa, Andrej
    et al.
    Krc, Janez
    Malmström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Smole, Franc
    Topic, Marko
    Optical potential of TCO/metal back contact and of textured substrate in thin Cu(In,Ga)Se2 solar cells2006Conference paper (Refereed)
  • 20.
    Coronel, Ernesto
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Microstructural characterization of Zn1-XMgXO buffers layer in CIGS solar cells2007Conference paper (Other academic)
  • 21.
    Cunha, J. M. V.
    et al.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Fernandes, P. A.
    Univ Aveiro, I3N, P-3810193 Aveiro, Portugal;Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Inst Politecn Porto, Inst Super Engn Porto, Dept Fis, CIETI, P-4200072 Porto, Portugal.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Teixeira, J. P.
    Univ Aveiro, I3N, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, P-3810193 Aveiro, Portugal.
    Bose, S.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Vermang, B.
    IMEC Partner Solliance, B-3001 Leuven, Belgium;Univ Hasselt Partner Solliance, B-3590 Diepenbeek, Belgium;IMOMEC Partner Solliance, B-3590 Diepenbeek, Belgium.
    Garud, S.
    IMEC Partner Solliance, B-3001 Leuven, Belgium;Univ Hasselt Partner Solliance, B-3590 Diepenbeek, Belgium;IMOMEC Partner Solliance, B-3590 Diepenbeek, Belgium.
    Buldu, D.
    IMEC Partner Solliance, B-3001 Leuven, Belgium;Univ Hasselt Partner Solliance, B-3590 Diepenbeek, Belgium;IMOMEC Partner Solliance, B-3590 Diepenbeek, Belgium.
    Gaspar, J.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Leitao, J. P.
    Univ Aveiro, I3N, P-3810193 Aveiro, Portugal;Univ Aveiro, Dept Fis, P-3810193 Aveiro, Portugal.
    Salome, P. M. P.
    Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, P-3810193 Aveiro, Portugal.
    Insulator Materials for Interface Passivation of Cu(In,Ga)Se-2 Thin Films2018In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, no 5, p. 1313-1319Article in journal (Refereed)
    Abstract [en]

    In this work, metal-insulator-semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al2O3), silicon nitride, and silicon oxide (SiOx) to be used as passivation layers in Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance versus conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q(f)). The density of interface defects (D-it) was estimated from capacitance versus conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 degrees C) and the use of a sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiOx deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower Dit values was Al2O3 when deposited by sputtering.

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  • 22.
    Cunha, Jose M., V
    et al.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Lopes, Tomas S.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Bose, Sourav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Ribeiro, Rodrigo M.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Oliveira, Antonio J. N.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fernandes, Paulo A.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal;Inst Politecn Porto, Inst Super Engn Porto, Dept Fis, CIETI, P-4200072 Porto, Portugal.
    Salome, Pedro M. P.
    INL Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.
    Decoupling of Optical and Electrical Properties of Rear Contact CIGS Solar Cells2019In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 9, no 6, p. 1857-1862Article in journal (Refereed)
    Abstract [en]

    A novel architecture that comprises rear interface passivation and increased rear optical reflection is presented with the following advantages: i) enhanced optical reflection is achieved by the deposition of a metallic layer over the Mo rear contact; ii) improved interface qualitywithCIGS by adding a sputteredAl 2O 3 layer over the metallic layer; and, iii) optimal ohmic electrical contact ensured by rear-openings refilling with a second layer of Mo as generally observed from the growth of CIGS on Mo. Hence, a decoupling between the electrical function and the optical purpose of the rear substrate is achieved. We present in detail the manufacturing procedure of such type of architecture together with its benefits and caveats. A preliminary analysis showing an architecture proof-of-concept is presented and discussed.

  • 23.
    Cunha, Jose M. V.
    et al.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal..
    Oliveira, Kevin
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Lontchi, Jackson
    Catholic Univ Louvain, ICTEAM Inst, Pl Levant 3, B-1348 Louvain La Neuve, Belgium..
    Lopes, Tomas S.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Hasselt Univ Partner Solliance, Inst Mat Res IMO, Agoralaangebouw H, B-3590 Diepenbeek, Belgium.;IMOMEC Partner Solliance, IMEC Div, Wetenschapspk 1, B-3590 Diepenbeek, Belgium.;EnergyVille, Thorpk,Poort Genk 8310 & 8320, B-3600 Genk, Belgium..
    Curado, Marco A.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Univ Coimbra, CFisUC, Dept Phys, P-3004516 Coimbra, Portugal..
    Barbosa, Joao R. S.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Vinhais, Carlos
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Inst Politecn Porto, Inst Super Engn Porto, Dept Fis, P-4200072 Porto, Portugal..
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Borme, Jerome
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Fonseca, Helder
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Gaspar, Joao
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Flandre, Denis
    Catholic Univ Louvain, ICTEAM Inst, Pl Levant 3, B-1348 Louvain La Neuve, Belgium..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Silva, Ana G.
    Univ Nova Lisboa, CEFITEC, Fac Ciencias & Tecnol, Dept Fis, Campus Caparica, P-2829516 Lisbon, Portugal..
    Teixeira, Jennifer P.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal..
    Fernandes, Paulo A.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Univ Aveiro, I3N, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Inst Politecn Porto, Inst Super Engn Porto, CIETI, Dept Fis, P-4200072 Porto, Portugal..
    Salome, Pedro M. P.
    INL Int Iberian Nanotechnol Lab, Ave Mestre Jose Veiga, P-4715330 Braga, Portugal.;Univ Aveiro, Dept Fis, Campus Univ Santiago, P-3810193 Aveiro, Portugal.;Inst Politecn Porto, Inst Super Engn Porto, CIETI, Dept Fis, P-4200072 Porto, Portugal..
    High-Performance and Industrially Viable Nanostructured SiOx Layers for Interface Passivation in Thin Film Solar Cells2021In: Solar RRL, E-ISSN 2367-198X, Vol. 5, no 3, article id 2000534Article in journal (Refereed)
    Abstract [en]

    Herein, it is demonstrated, by using industrial techniques, that a passivation layer with nanocontacts based on silicon oxide (SiOx) leads to significant improvements in the optoelectronical performance of ultrathin Cu(In,Ga)Se-2 (CIGS) solar cells. Two approaches are applied for contact patterning of the passivation layer: point contacts and line contacts. For two CIGS growth conditions, 550 and 500 degrees C, the SiOx passivation layer demonstrates positive passivation properties, which are supported by electrical simulations. Such positive effects lead to an increase in the light to power conversion efficiency value of 2.6% (absolute value) for passivated devices compared with a nonpassivated reference device. Strikingly, both passivation architectures present similar efficiency values. However, there is a trade-off between passivation effect and charge extraction, as demonstrated by the trade-off between open-circuit voltage (V-oc) and short-circuit current density (J(sc)) compared with fill factor (FF). For the first time, a fully industrial upscalable process combining SiOx as rear passivation layer deposited by chemical vapor deposition, with photolithography for line contacts, yields promising results toward high-performance and low-cost ultrathin CIGS solar cells with champion devices reaching efficiency values of 12%, demonstrating the potential of SiOx as a passivation material for energy conversion devices.

  • 24.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB, Vallvägen 5, Uppsala,Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Secondary phase formation and surface modification from a high dose KF-post deposition treatment of (Ag,Cu)(In,Ga)Se-2 solar cell absorbers2019In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 27, no 3, p. 220-228Article in journal (Refereed)
    Abstract [en]

    In this study, we assessed the potential of KF-post deposition treatment (PDT) performed on a silver-alloyed Cu (In,Ga)Se-2 (ACIGS) solar absorber. ACIGS absorbers with Ag/Ag + Cu ratio (Ag/I) close to 20% were co-evaporated on a Mo-coated glass substrate and exposed to in-situ KF-PDT of various intensities. The current-voltage characteristics indicated that an optimized PDT can be beneficial, increasing in our study the median V-oc and efficiency values by +48 mV and + 0.9%(abs) (from 728 mV and 16.1% efficiency measured for the sample without PDT), respectively. However, an increased KF-flux during PDT resulted in a net deterioration of the performance leading to median V-oc and efficiency values as low as 503 mV and 4.7%. The chemical composition analysis showed that while the reference absorber without any post deposition treatment (PDT) was homogeneous, the KF-PDT induced a clear change within the first 10 nm from the surface. Here, the surface layer composition was richer in K and In with an increased Ag/I ratio, and its thickness seemed to follow the KF exposure intensity. Additionally, high-dose KF-PDT resulted in substantial formation of secondary phases for the ACIGS. The secondary phase precipitates were also richer in Ag, K, and In, and electron and X-ray diffraction data match with the monoclinic C 1 2/c 1 space group adopted by the Ag-alloyed KInSe2 phase. It could not be concluded whether the performance loss for the solar cell devices originated from the thicker surface layer or the presence of secondary phases, or both for the high-dose KF-PDT sample.

  • 25.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Surface Modification And Secondary Phase Formation From a High Dose KF-Post Deposition Treatment of (Ag,Cu)(In,Ga)Se2 Solar Cell AbsorbersIn: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159XArticle in journal (Refereed)
    Abstract [en]

    In this study we assessed the potential of KF-Post Deposition Treatment (PDT) performed on a silver-alloyed Cu(Inx,Ga1-x)Se2 (ACIGS) solar absorber. ACIGS absorbers with Ag/Ag+Cu ratio (Ag/I) close to 20% were co-evaporated on a Mo-coated glass substrate and exposed to in-situ KF-PDT of various intensities. The current-voltage characteristics indicated that an optimized PDT can be beneficial, increasing in our study the median Voc and efficiency values by +48 mV and +0.9 %abs (from 728 mV and 16.1 % efficiency measured for the sample without PDT), respectively. However, an increased KF-flux during PDT resulted in a net deterioration of the performance leading to median Voc and efficiency values as low as 503 mV and 4.7 %. The chemical composition analysis showed that while the reference absorber without any PDT was homogeneous, the KF-PDT induced a clear change within the first 10 nm from the surface. Here, the surface layer composition was richer in K and In with an increased Ag/I ratio, and its thickness seemed to follow the KF exposure intensity. Additionally, high-dose KF-PDT resulted in substantial formation of secondary phases for the ACIGS. The secondary phase precipitates were also richer in Ag, K and In, and Electron and X-ray diffraction data match with the monoclinic C 1 2/c 1 space group adopted by the Ag-alloyed KInSe2 (AKIS) phase. It could not be concluded whether the performance loss for the solar cell devices originated from the thicker surface layer or the presence of secondary phases, or both for the high-dose KF-PDT sample.

  • 26.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, T.
    Stockholm University, Department of Materials and Environmental Chemistry 106 91 Stockholm.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wallin, E.
    Solibro Research AB, Vallvägen 5, Uppsala, Sweden.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB, Vallvägen 5, Uppsala, Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Cu-depleted patches induced by presence of K during growth of CIGS absorbers2017Conference paper (Refereed)
    Abstract [en]

    The conversion efficiency of the CIGS thin film solar cells has rapidly increased since introduction of the heavier alkali-doping (K, Rb, Cs). While the exclusive introduction of Na in the CIGS films has led to efficiencies up to 20,4% 1, the latest K, Rb or Cs post deposition treatments (PDT) have increased the efficiency to 22,6% 2. The exact role of this heavy-alkali PDT is still under discussion but three explanations have been discussed in the literature. First, that the heavy alkali PDT facilitates CdCu substitution, that results in an enhanced absorber type inversion, moving the p-n junction further into the CIGS bulk 3. Second, that the main effect from heavy alkali PDT is due to the formation of a K-In-Se2 layer, that passivates defects at the CIGS surface, reducing interface recombination 4. And third, that the heavy alkali PDT induces a Cu depletion at the surface of the CIGS which, by increasing the local Fermi level, increases the band bending; thus creating a higher potential barrier for holes to recombine 5.

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  • 27.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Fourdrinier, Lionel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Surface defect passivation by a thin metallic barrier for Cu(InxGa1-x)Se2 co-evaporation on Cr-steel substrates2016In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 619, p. 220-226Article in journal (Refereed)
    Abstract [en]

    The use of Cr-steel substrates for the fabrication of Cu(In,Ga)Se2 (CIGS) solar cells is highly desirable and is a topic of considerable research interest. However, solar cells on non-treated steel substrates often exhibit decreased performance compared to their homologues on soda lime glass substrates. This is partly attributed to out-diffusion of steel components (Fe, Cr, Mn, etc.) into the solar cell. To avoid this contamination, thin film barriers can be added on top of the steel surface, but they do not always prevent the diffusion completely. In this paper we study the potential of using Cr and Ti as thin barrier layers. We find that local surface defects on the steel, several micrometers in height, lead to cracks in the back contact as well as in the barrier layers. Advanced transmission electron microscopy (TEM) techniques reveal that elemental diffusion and chemical reactions occur at these openings during heat treatments in Se atmosphere. TEM-energy dispersive X-ray spectroscopy (TEM-EDX) analysis in combination with calculation of the solid state diffusion coefficient demonstrate that a Cr-barrier sacrificially protects the Cr-steel substrate, blocking most of the Fe out-diffusion, whereas a Ti-barrier is less efficient.

  • 28.
    Donzel-Gargand, Olivier
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thersleff, Thomas
    Stockholms Univ, Nat Skapliga Fak, Inst Mat & Miljokemi, Stockholm.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wallin, Erik
    Solibro Research AB, Uppsala, Sweden.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Research AB, Uppsala, Sweden.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Deep surface Cu depletion induced by K in high-efficiency Cu(In,Ga)Se2 solar cell absorbers2018In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 9, p. 730-739Article in journal (Refereed)
    Abstract [en]

    In this work, we used K‐rich glass substrates to provide potassium during the coevaporation of Cu(In,Ga)Se2 (CIGS) absorber layers. Subsequently, we applied a postdeposition treatment (PDT) using KF or RbF to some of the grown absorbers. It was found that the presence of K during the growth of the CIGS layer led to cell effi- ciencies beyond 17%, and the addition of a PDT pushed it beyond 18%. The major finding of this work is the observation of discontinuous 100‐ to 200‐nm‐deep Cu‐ depleted patches in the vicinity of the CdS buffer layer, correlated with the presence of K during the growth of the absorber layer. The PDT had no influence on the forma- tion of these patches. A second finding concerns the composition of the Cu‐depleted areas, where an anticorrelation between Cu and both In and K was measured using scanning transmission electron microscopy. Furthermore, a steeper Ga/(In+Ga) ratio gradient was measured for the absorbers grown with the presence of K, suggesting that K hinders the group III element interdiffusion. Finally, no Cd in‐diffusion to the CIGS layer could be detected. This indicates that if CdCu substitution occurs, either their concentration is below our instrumental detection limit or its presence is contained within the first 6 nm from the CdS/CIGS interface.

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  • 29.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Thin Film Solar Cells: Research in an Industrial Perspective2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no Suppl 2, p. 112-118Article in journal (Refereed)
    Abstract [en]

    Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se-2 and Cu2ZnSn(S,Se)(4) as the sunlight-absorbing layer.

  • 30.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Using both sides of the panel2023In: Nature Energy, E-ISSN 2058-7546, Vol. 8, no 1, p. 15-16Article in journal (Other academic)
    Abstract [en]

    Bifaciality allows the harvest of sunlight from both sides of a solar cell and thereby increases power output, but the efficiency of thin-film devices lags behind that of silicon counterparts. Now, researchers demonstrate a bifacial Cu(In,Ga)Se2-perovskite tandem solar cell with a 28 mW/cm2 power output under front and rear illumination.

  • 31.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Gordon, Ivan
    imec.
    Vermang, Bart
    imec.
    Bolt, Pieter Jan
    TNO.
    van Deelen, Joop
    TNO.
    Simor, M
    TNO.
    Flandre, Denis
    Universite Catholique de Louvain.
    Lontchi, Jackson
    Universite Catholique de Louvain.
    Kovacic, Milan
    University of Ljubljana.
    Krc, Janez
    University of Ljubljana.
    Topic, Marco
    University of Ljubljana.
    Gouillard, Louis
    Univ. Paris-Sud, Université Paris-Saclay.
    Collin, Stephane
    Univ. Paris-Sud, Université Paris-Saclay.
    Cattoni, Andrea
    Univ. Paris-Sud, Université Paris-Saclay.
    Naghavi, Negar
    IPVF.
    Jubault, Marie
    Electricité de France.
    Kotipalli, Ratan
    AC&CS.
    Fourdrinier, Lionel
    AC&CS.
    Ye, Zhou
    Obducat AB.
    Vignal, Renaud
    Arcelor Mittal.
    Gusak, Viktoria
    Solibro Research AB.
    Takei, Klara
    Midsummer AB.
    Niemi, Esko
    Midsummer AB.
    Bose, Sourav
    INL.
    da Cunha, J. M. V.
    INL.
    Anacleto, Pedro
    INL.
    Lopez, T. S.
    INL.
    Fernandez, P. A.
    INL.
    Sadewasser, S.
    INL.
    Salomé, Pedro
    INL.
    Ultrathin CIGS Solar Cells with Passivated and Highly Reflective Back Contacts –: Results from the ARCIGS-M Consortium2019In: Proceedings of 36th European Photovoltaic Solar Energy Conference and Exhibition, 2019, p. 597-600, article id 3AO.8.1Conference paper (Other academic)
    Abstract [en]

    In this work, we report results from the EU-funded project ARCIGS-M. The project started in 2016 and aims to reduce the use of indium and gallium by enabling the use of very thin Cu(In,Ga)Se2 (CIGS) layers while retaining high efficiency and developing innovative low-cost steel substrates as alternatives to glass. In the project, reflective layers containing TCO´s and silver have successfully been used to enhance the reflective properties of the rear contact. In addition, passivation layers based on alumina (Al2O3) deposited by atomic layer deposition (ALD) have been found to yield good passivation of the rear contact. Since the alumina layers are dielectric, perforation of these layers is necessary to provide adequate contacting. The design of the perforation patterns has been investigated by a combination of modeling and experimental verification by electron beam lithography. In parallel a nano-imprint lithography (NIL) process is further developed for scale-up and application in prototype modules. Advanced optoelectrical characterization supported by modeling is used to fill in the missing gaps in optical and electrical properties, regarding CIGS, interfaces and back contact materials.

  • 32.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jarmar, Tobias
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Shariati Nilsson, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wallin, Erik
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Hogstrom, Daniel
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Stolt, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lundberg, Olle
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Shafarman, William
    Univ Delaware, Inst Energy Convers, Newark, DE 19716 USA..
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Solibro Res AB, S-75651 Uppsala, Sweden..
    High Voc in (Cu,Ag)(In,Ga)Se2 Solar Cells2017In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 7, no 6, p. 1789-1794Article in journal (Refereed)
    Abstract [en]

    In this contribution, we show that silver substitution for copper in Cu(In,Ga)Se-2 (CIGS) to form (Ag,Cu)(In, Ga)Se-2 (ACIGS) leads to a reduction of the voltage loss expressed as E-g/q-V-oc. This, in turn, leads to higher device efficiencies as compared to similar CIGS devices without Ag. We report V-oc at 814 mV at a conversion efficiency of 21% for our best ACIGS device with 20% of the group I element consisting of silver. Comparing ACIGS and CIGS devices with the same Ga/(Ga+ In) ratio, the ACIGS devices exhibit about 0.05 eV higher bandgap. Alkali postdeposition treatment with KF leads to improvements in efficiency both for CIGS and ACIGS, but we find that the dose of KF needed for optimum device for ACIGS is 10-20% of the dose used for CIGS.

  • 33.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Joel, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Vermang, Bart
    IMEC, Kapeldreef 75, B-3001 Leuven, Belgium..
    Hägglund, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Back Contact Passivation Effects in Bi-Facial Thin CIGS Solar Cells2016In: 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), IEEE , 2016, p. 3527-3529Conference paper (Refereed)
    Abstract [en]

    Bi-facial solar cells with ultrathin CIGS solar cells are fabricated to investigate the influence of back contact passivation. Solar cells with CIGS thicknesses of 300 and 500 nm and with an ultrathin transparent Mo layer are characterized using EQE measurements from both the front and the rear side as well as with I-V measurements. Back contact passivation consisting of Al2O3 deposited by atomic layer deposition and nano-sized point contact openings is used. The results are compared to cells with only the transparent Mo layer as back contact. We find a significant effect of the passivation manifested as an increase in the current density of the solar cells with the passivation.

  • 34.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindahl, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gas flow sputtering of Cu(In,Ga)Se-2 for thin film solar cells2015In: 2015 IEEE 42ND PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), 2015Conference paper (Refereed)
    Abstract [en]

    Gas flow sputtering of Cu(In,Ga)Se-2 (CIGS) from two opposing Cu(In,Ga)Se-2 targets with slightly Cu-poor stoichiometry was performed, using i) selenium only provided by the target and ii) using additional selenium from an elemental source inside the sputtering system. In both cases the composition of the sputtered CIGS film was similar to the target. A sputter process without additional selenium supply led to poor cell results at about 2 % efficiency. After introducing a posttreatment in selenium atmosphere immediately after the sputter deposition, the cell results were dramatically improved to 12 %. With selenium added during the sputtering process, 13.7 % conversion efficiency was obtained without any post treatment. Gas flow sputtering uses a high gas flow to transport the material from the plasma to the growing film, thereby the atoms will be thermalized, similarly to in an evaporation process. Reactant gases can be supplied close to the substrate, outside the plasma, thereby reducing the risk for sputter damage.

  • 35.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Malmberg, Lina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Malm, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Influence of CBD-deposited CdS on the carrier collection in CIGS-based solar cells2006Conference paper (Refereed)
  • 36.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Schleussner, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wallin, Erik
    Solibro Research AB.
    Lundberg, Olle
    Solibro Research AB.
    Technological and economical aspects on the influence of reduced Cu(In,Ga)Se2 thickness and Ga grading for co-evaporated Cu(In,Ga)Se2 modules2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 21, p. 7530-7533Article in journal (Refereed)
    Abstract [en]

    Reducing the Cu(In,Ga)Se2 (CIGS) thickness is one way of improving the throughput and capacity in existing production, provided that the efficiency can be kept at a high level. Our experimental results from an in-line co-evaporation process show that it is possible to produce CIGS solar cells with good efficiency at a CIGS thickness of less than 1 µm. An efficiency of 14.4% was obtained for an evaporation time of 8 min and a resulting CIGS thickness of only 0.8 [mu]m. The quantum efficiency measurements show only a minor reduction of the collection in the infrared region that can be related to losses caused by reduced absorption. Passivation of the back contact has been found to be important for thin devices and one way of obtaining good back contact properties, or to reduce the impact of back contact recombination is to use an increased Ga content near the back contact. We have found that Ga grading is feasible also in the three stage process, i.e. a Ga-rich layer near the back contact from stage one is to a high degree retained also after stages two and three. In this paper we discuss the implication of efficiency reduction for the economy of the production and how high efficiency loss that can be tolerated, provided that the output is doubled at equal production cost for the CIGS layer.

  • 37.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Stolt, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Shariati Nilsson, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Stolt, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology. Solibro Res AB, Vallvagen 5, Uppsala, Sweden..
    Post Deposition Treatments of (Ag,Cu)(In,Ga)Se-2 Thin Films for Solar Cells2019In: 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC), New York: IEEE, 2019, p. 618-621Conference paper (Refereed)
    Abstract [en]

    Different alkali alternatives for post-deposition of ACIGS were tested, both conventional fluoride salts and in the form of metals. XPS analysis of surfaces treated with K or KF as well as Rb or RbF have been performed, before (only for K and Rb) and after an ammonia etch. In addition to a strong suppression of Cu and Ag near the surface, we observe a difference in the re-distribution of Ga in the surface region after the etch depending on pdt element. Our results are consistent with the formation of K-In-Se and Rb-In-Se compounds for both metal alkalis and alkali fluorides. We find a similar beneficial effect on cell performance for the best cells with the metals as with the fluoride salts.

  • 38.
    Edoff, Marika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Viard, Nicolas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Jörn Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Schleussner, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Westin, Per-Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Sputtering of highly adhesive Mo back contact layers for Cu(In,Ga)Se2 solar cells2009Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    In this work the sputter process for back contact Mo layers was adjusted to increase the adhesive strength of the Mo layers to the glass substrate, while keeping a high deposition rate and high conductivity. Mo layers were fabricated using DC magnetron sputtering in an in-line sputtering system. The adhesive strength was tested with ultrasonic agitation. The combination of good adhesion and high deposition rate was obtained by using a double layer, where the thickness of the first adhesion layer was varied between 25 and 100 nm and sputtered at 15 mTorr, whereas the second bulk layer was varied between 300 and 600 nm and sputtered at 6 mTorr. Solar cells were prepared for all different thicknesses of the adhesive layer and showed similar performance.

  • 39.
    Edoff, Marika
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Woldegiorgis, Sara
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Neretnicks, Peter
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Ruth, Marta
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Stolt, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Kessler, John
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    CIGS Submodules with High Performance and High Manufacturability2004In: 19th European Photovoltaic Solar Energy Conference and Exhibition, Paris, 7-11 June, 2004Conference paper (Other scientific)
  • 40.
    Fjällström, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Salome, P. M. P.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hultqvist, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jarmar, T.
    Aitken, B. G.
    Zhang, K.
    Fuller, K.
    Williams, C. Kosik
    Potential-Induced Degradation of CuIn1-xGaxSe2 Thin Film Solar Cells2013In: IEEE Journal of Photovoltaics, ISSN 2156-3381, Vol. 3, no 3, p. 1090-1094Article in journal (Refereed)
    Abstract [en]

    The use of Na-free or low Na content glass substrates is observed to enhance the resiliency to potential-induced degradation, as compared with glass substrates with high Na content, such as soda lime glass (SLG). The results from stress tests in this study suggest that degradation caused by a combination of heat and bias across the SLG substrate is linked to increased Na concentration in the CdS and Cu(In,Ga)Se-2 (CIGS) layers in CIGS-based solar cells. The degradation during the bias stress is dramatic. The efficiency drops to close to 0% after 50 h of stressing. On the other hand, cells on Na-free and low Na content substrates exhibited virtually no efficiency degradation. The degraded cells showed partial recovery by resting at room temperature without bias; thus, the degradation is nonpermanent and may be due to Na migration and accumulation rather than chemical reaction.

  • 41.
    Fjällström, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Szaniawski, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Vermang, Bart
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Salome, Pedro M. P.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rostvall, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zimmermann, Uwe
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Recovery After Potential-Induced Degradation of CuIn1-xGaxSe2 Solar Cells With CdS and Zn(O,S) Buffer Layers2015In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 5, no 2, p. 664-669Article in journal (Refereed)
    Abstract [en]

    This study deals with potential-induced degradation (PID) of Cu(In,Ga)Se-2-based solar cells and different approaches to subsequent recovery of efficiency. Three different recovery methods were studied: 1) etch recovery, 2) accelerated recovery, and 3) unaccelerated recovery. After being completely degraded, the solar cells with CdS buffer layers recovered their efficiencies at different rates, depending on the method which was used. On the other hand, if Zn(O,S) was used as a buffer layer instead of CdS, the recovery rate was close to zero. The buffer layer type clearly influenced the sodium distribution during PID stressing and recovery, as well as the possibilities for recovery of the electrical performance.

  • 42.
    Frisk, Christopher
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Szaniawski, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wätjen, Timo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fjällström, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Salome, P.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Optimizing Ga-profiles for highly efficient Cu(In,Ga)Se2 thin film solar cells in simple and complex defect models2014In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 47, no 48, p. 485104-Article in journal (Refereed)
    Abstract [en]

    Highly efficient Cu(In,Ga)(S,Se)2 photovoltaic thin film solar cells often have a compositional variation of Ga to In in the absorber layer, here described as a Ga-profile. In this work we have studied the role of Ga-profiles in four different models, based on input data from electrical and optical characterizations of an in-house state-of-the-art Cu(In,Ga)Se2 (CIGS) solar cell with power conversion efficiency above 19 %. A simple defect model with mid-gap defects in the absorber layer was compared with models with Ga-dependent defect concentrations and amphoteric defects. In these models optimized single-graded Ga-profiles have been compared with optimized double-graded Ga-profiles. It was found that the defect concentration for effective Shockley-Read-Hall recombination is low for high efficiency CIGS devices and that the doping concentration of the absorber layer, chosen according to the defect model, is paramount when optimizing Ga-profiles. For optimized single-graded Ga-profiles the simulated power conversion efficiency, depending on the model, is 20.5-20.8 %, and the equivalent double-graded Ga-profiles yield 20.6-21.4 %, indicating that the bandgap engineering of the CIGS device structure can lead to improvements in efficiency. Apart from the effects of increased doping in the complex defect models, the results are similar when comparing the complex defect models to the simple defect models. 

    Download full text (pdf)
    Optimizing_Ga-profiles_2014
  • 43.
    Frisk, Christopher
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fjällström, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Salomé, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Olsson, Jörgen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Modeling Ga-profiles for Cu(In,Ga)Se2 thin film solar cells with varying defect density2013In: 23rd International Photovoltaic Science and Engineering Conference; Taipei, Taiwan; October 28 - Nov 1, 2013: Proceedings, 2013Conference paper (Refereed)
    Abstract [en]

    The very best Cu(In,Ga)(S,Se)2 solar cells have a double graded band gap in the absorber, i.e. a notch profile, formed by varying the ratio of Ga to In. If this is a prerequisite or a consequence of high quality deposition methods is something yet of discussion. In this work we have constructed a high efficiency model (HE-T61) based on in-house state-of-the art Cu(In,Ga)Se2 solar cells, with efficiencies above 19 %, and investigated the role of the Ga-profile. Notch-type Ga-profiles have been compared with single graded profiles, and the influence of Ga-dependent defect distribution and metastable defects have been investigated showing that the optimum Ga-profile is dependent on such defect variations. It is also shown that within the HE-T61 model the optimized Ga-profile yields up to 3 % absolute efficiency gain, indicating that there is potential in band gap engineering.

    Download full text (pdf)
    Modeling Ga-profiles for CIGS thin film solar cells with varying defect density
  • 44.
    Gouillart, Louis
    et al.
    Univ Paris Saclay, CNRS, Ctr Nanosci & Nanotechnol C2N, 10 Blvd Thomas Gobert, F-91120 Palaiseau, France.;CNRS, UMR 9006, IPVF, 18 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Cattoni, Andrea
    Univ Paris Saclay, CNRS, Ctr Nanosci & Nanotechnol C2N, 10 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Goffard, Julie
    Univ Paris Saclay, CNRS, Ctr Nanosci & Nanotechnol C2N, 10 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Jubault, Marie
    EDF R&D, IPVF, 18 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Naghavi, Negar
    CNRS, UMR 9006, IPVF, 18 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Collin, Stephane
    Univ Paris Saclay, CNRS, Ctr Nanosci & Nanotechnol C2N, 10 Blvd Thomas Gobert, F-91120 Palaiseau, France..
    Interface engineering of ultrathin Cu(In,Ga)Se2 solar cells on reflective back contacts2021In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 29, no 2, p. 212-221Article in journal (Refereed)
    Abstract [en]

    Cu(In,Ga)Se-2-based (CIGS) solar cells with ultrathin (<= 500 nm) absorber layers suffer from the low reflectivity of conventional Mo back contacts. Here, we design and investigate ohmic and reflective back contacts (RBC) made of multilayer stacks that are compatible with the direct deposition of CIGS at 500 degrees C and above. Diffusion mechanisms and reactions at each interface and in the CIGS layer are carefully analyzed by energy dispersive X-ray (EDX)/scanning transmission electron microscopy (STEM). It shows that the highly reflective silver mirror is efficiently encapsulated in ZnO:Al layers. The detrimental reaction between CIGS and the top In2O3:Sn (ITO) layer used for ohmic contact can be mitigated by adding a 3 nm thick Al2O3 layer and by decreasing the CIGS coevaporation temperature from 550 degrees C to 500 degrees C. It also improves the compositional grading of Ga toward the CIGS back interface, leading to increased open- circuit voltage and fill factor. The best ultrathin CIGS solar cell on RBC exhibits an efficiency of 13.5% (+1.0% as compared to our Mo reference) with a short-circuit current density of 28.9 mA/cm(2) (+2.6 mA/cm(2)) enabled by double-pass absorption in the 510 nm thick CIGS absorber. RBC are easy to fabricate and could benefit other photovoltaic devices that require highly reflective and conductive contacts subject to high temperature processes.

  • 45.
    Gouillart, Louis
    et al.
    Ctr Nanosci & Nanotechnol C2N, Inst Photovolta Ile France IPVF, UMR CNRS, CNRS, Palaiseau, France.
    Cattoni, Andrea
    Ctr Nanosci & Nanotechnol C2N, CNRS, Palaiseau, France.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Zeitouny, Joya
    Ctr Nanosci & Nanotechnol C2N, CNRS, Palaiseau, France.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Jubault, Marie
    IPVF, EDF R&D, Palaiseau, France.
    Naghavi, Negar
    Inst Photovolta Ile France IPVF, UMR CNRS, Palaiseau, France.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Collin, Stéphane
    Ctr Nanosci & Nanotechnol C2N, CNRS, Palaiseau, France.
    Ultrathin Cu(In,Ga)Se2 solar cells with Ag-based reflective back contacts2020In: 2020 47th IEEE Photovoltaic Specialists Conference (PVSC), 2020, p. 1481-1484Conference paper (Refereed)
    Abstract [en]

    We developed a highly reflective back contact for Cu(In,Ga)Se 2 solar cells based on silver encapsulated in a TCOs stack, compatible with substrate configuration. We demonstrated ultrathin (500 nm) Cu(In,Ga)Se 2 solar cells with 13.5% efficiency and state-of-the-art JSC=28.9 mA/cm2,2.7 mA/cm 2 more than the reference cell on molybdenum. We also demonstrated a 530 nm-thick (Ag, Cu)(In,Ga)Se 2 solar cell on Mo with state-of-the-art efficiency (14.9%) and remarkably high V OC (741 mV) and FF (81.8%). This result coupled with a highly reflective back contact for improved J SC , has the potential for a 500 nm-thick (Ag, Cu)(In,Ga)Se 2 solar cell with an 18% efficiency.

  • 46.
    Gouillart, Louis
    et al.
    Univ Paris Sud, Ctr Nanosci & Nanotechnol C2N, CNRS, F-91120 Palaiseau, France; CNRS, UMR 9006, IPVF, F-91120 Palaiseau, France.
    Chen, Wei-Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Cattoni, Andrea
    Univ Paris Sud, Ctr Nanosci & Nanotechnol C2N, CNRS, F-91120 Palaiseau, France.
    Goffard, Julie
    Univ Paris Sud, Ctr Nanosci & Nanotechnol C2N, CNRS, F-91120 Palaiseau, France.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Electrical Engineering, Solid-State Electronics.
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Jubault, Marie
    EDF R&D, IPVF, F-91120 Palaiseau, France.
    Naghavi, Negar
    CNRS, UMR 9006, IPVF, F-91120 Palaiseau, France.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Collin, Stéphane
    Univ Paris Sud, Ctr Nanosci & Nanotechnol C2N, CNRS, F-91120 Palaiseau, France.
    Reflective Back Contacts for Ultrathin Cu(In,Ga)Se2-Based Solar Cells2020In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 10, no 1, p. 250-254Article in journal (Refereed)
    Abstract [en]

    We report on the development of highly reflective back contacts (RBCs) made of multilayer stacks for ultrathin CIGS solar cells. Two architectures are compared: they are made of a silver mirror coated either with a single layer of In 2 O 3 :Sn (ITO) or with a bilayer of ZnO:Al/ITO. Due to the improvement of CIGS rear reflectance, both back contacts result in a significant external quantum efficiency enhancement, in agreement with optical simulations. However, solar cells fabricated with Ag/ITO back contacts exhibit a strong shunting behavior. The key role of the ZnO:Al layer to control the morphology of the top ITO layer and to avoid silver diffusion through the back contact is highlighted. For a 500-nm-thick CIGS layer, this optimized RBC leads to a best cell with a short-circuit current of 27.8 mA/cm 2 (+2.2 mA/cm 2 as compared to a Mo back contact) and a 12.2%-efficiency (+2.5% absolute).

  • 47. Holt, A.
    et al.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lund, P.
    Lauritzen, H.
    Reenaas, T. W.
    Mellikov, E.
    Lantratov, V. M.
    Nordic Centre of Excellence in Photovoltaics (NCOE in PV)2008Conference paper (Refereed)
    Abstract [en]

    A NCoE in PV has been formed by seven research institutions in the Nordic region. The centre is funded by Nordic Energy Research, Renewable Energy Corporation ASA, Elkem Solar AS, Solibro Research AB, Topsil A/S, Energinet.dk, and Luvata as well as the participating research organisations. The main objective is to strengthen the already formed Nordic R&D network and to serve the fast-growing and demanding Nordic PV industry. This will be achieved by educating PhD students with compulsory mobility of the students, arranging general workshops within solar cell research, organizing in-depth workshops on selected topics, giving hands-on workshops on processing of solar cells, and actively disseminate results both in public and scientific media channels.

  • 48.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Aitola, Kerttu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sveinbjörnsson, Kári
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Saki, Zahra
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Sharif Univ Technol, Tehran, Iran.
    Larsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 35, p. 29707-29716Article in journal (Refereed)
    Abstract [en]

    The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH2)(2), CH3NH3)Pb(I,Br)(3) (FAPbI(3):MAPbBr(3)) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnOx. Exposing the samples to the heat, the vacuum, and even the counter reactant of H2O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C2H5)(2) either by itself or in combination with H2O during the ZnO atomic layer deposition (ALD) process is found to enhance the decomposition of the bulk of the perovskite film into PbI2 without even forming ZnO. In contrast, the Sn precursor Sn(N(CH3)(2))(4) does not seem to degrade the bulk of the perovskite film, and conformal SnOx films can successfully be grown on top of it using atomic layer deposition. Using this SnOx film as the electron selective layer in inverted perovskite solar cells results in a lower power conversion efficiency of 3.4% than the 8.4% for the reference devices using phenyl-C-70-butyric acid methyl ester. However, the devices with SnOx show strong hysteresis and can be pushed to an efficiency of 7.8% after biasing treatments. Still, these cells lacks both open circuit voltage and fill factor compared to the references, especially when thicker SnOx films are used. Upon further investigation, a possible cause of these losses could be that the perovskite/SnOx interface is not ideal and more specifically found to be rich in Sn, O, and halides, which is probably a result of the nucleation during the SnOx growth and which might introduce barriers or alter the band alignment for the transport of charge carriers.

  • 49.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Evaluation of Zn-Sn-O buffer layers for CuIn0.5Ga0.5Se2 solar cells2011In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 19, no 4, p. 478-481Article in journal (Refereed)
    Abstract [en]

    Thin Zn-Sn-O films are evaluated as new buffer layer material for Cu(In,Ga)Se-2-based solar cell devices. A maximum conversion efficiency of 13.8% (V-oc = 691 mV, J(sc)(QE) = 27.9 mA/cm(2), and FF = 71.6%) is reached for a solar cell using the Zn-Sn-O buffer layer which is comparable to the efficiency of 13.5% (V-oc - 706 mV, J(sc)(QE) - 26.3 mA/cm(2), and FF = 72.9%) for a cell using the standard reference CdS buffer layer. The open circuit voltage (V-oc) and the fill factor (FF) are found to increase with increasing tin content until an optimum in both parameters is reached for Sn/(Zn+Sn) values around 0.3-0.4.

  • 50.
    Hultqvist, Adam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Jacobsson, T. Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Helmholtz Ctr Berlin, Div Renewable Energies, D-14109 Berlin, Germany.
    Svanström, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, S-11428 Stockholm, Sweden.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Törndahl, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    SnOx Atomic Layer Deposition on Bare Perovskite: An Investigation of Initial Growth Dynamics, Interface Chemistry, and Solar Cell Performance2021In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 4, no 1, p. 510-522Article in journal (Refereed)
    Abstract [en]

    High-end organic–inorganic lead halide perovskite semitransparent p–i–n solar cells for tandem applications use a phenyl-C61-butyric acid methyl ester (PCBM)/atomic layer deposition (ALD)-SnOx electron transport layer stack. Omitting the PCBM would be preferred for manufacturing, but has in previous studies on (FA,MA)Pb(Br,I)3 and (Cs,FA)Pb(Br,I)3 and in this study on Cs0.05FA0.79MA0.16PbBr0.51I2.49 (perovskite) led to poor solar cell performance because of a bias-dependent light-generated current. A direct ALD-SnOx exposure was therefore suggested to form a nonideal perovskite/SnOx interface that acts as a transport barrier for the light-generated current. To further investigate the interface formation during the initial ALD SnOx growth on the perovskite, the mass dynamics of monitor crystals coated by partial p–i–n solar cell stacks were recorded in situ prior to and during the ALD using a quartz crystal microbalance. Two major finds were made. A mass loss was observed prior to ALD for growth temperatures above 60 °C, suggesting the decomposition of the perovskite. In addition, a mostly irreversible mass gain was observed during the first exposure to the Sn precursor tetrakis(dimethylamino)tin(IV) that is independent of growth temperature and that disrupts the mass gain of the following 20–50 ALD cycles. The chemical environments of the buried interface were analyzed by soft and hard X-ray photoelectron spectroscopy for a sample with 50 ALD cycles of SnOx on the perovskite. Although measurements on the perovskite bulk below and the SnOx film above did not show chemical changes, additional chemical states for Pb, Br, and N as well as a decrease in the amount of I were observed in the interfacial region. From the analysis, these states and not the heating of the perovskite were concluded to be the cause of the barrier. This strongly suggests that the detrimental effects can be avoided by controlling the interfacial design.

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    FULLTEXT01
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