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Donzel-Gargand, OlivierORCID iD iconorcid.org/0000-0002-2101-3746
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Publications (10 of 23) Show all publications
Donzel-Gargand, O., Larsson, F., Törndahl, T., Stolt, L. & Edoff, M. (2019). Secondary phase formation and surface modification from a high dose KF-post deposition treatment of (Ag,Cu)(In,Ga)Se-2 solar cell absorbers. Progress in Photovoltaics, 27(3), 220-228
Open this publication in new window or tab >>Secondary phase formation and surface modification from a high dose KF-post deposition treatment of (Ag,Cu)(In,Ga)Se-2 solar cell absorbers
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2019 (English)In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 27, no 3, p. 220-228Article in journal (Refereed) Published
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.

National Category
Energy Systems
Identifiers
urn:nbn:se:uu:diva-379027 (URN)10.1002/pip.3080 (DOI)000459179000003 ()
Funder
Swedish Energy Agency, P43238-1Swedish Research Council, P43523-1Swedish Energy Agency, P43238-1
Available from: 2019-03-12 Created: 2019-03-12 Last updated: 2019-03-12Bibliographically approved
Larsson, F., Donzel-Gargand, O., Keller, J., Edoff, M. & Törndahl, T. (2018). Atomic layer deposition of Zn(O,S) buffer layers for Cu(In,Ga)Se-2 solar cells with KF post-deposition treatment. Solar Energy Materials and Solar Cells, 183, 8-15
Open this publication in new window or tab >>Atomic layer deposition of Zn(O,S) buffer layers for Cu(In,Ga)Se-2 solar cells with KF post-deposition treatment
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2018 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 183, p. 8-15Article in journal (Refereed) Published
Abstract [en]

We investigate the possibility to combine Zn(O,S) buffer layers grown by atomic layer deposition (ALD) with KF post-deposition treated Cu(In,Ga)Se-2 (CIGS-KF) in solar cells. It is shown that the beneficial effect on open-circuit voltage from the post-deposition treatment is essentially independent of buffer layer material. However, a wet chemical surface treatment is required prior to ALD in order to achieve competitive fill factor values. A water rinse is sufficient to create an absorber surface similar to the one formed during a conventional CdS chemical bath deposition process. However, it is observed that CIGS-KF/Zn(O,S) devices made with water-rinsed absorbers systematically result in lower fill factor values than for the corresponding CIGS-KF/CdS references. This effect can be mitigated by decreasing the H2S:H2O precursor ratio during ALD initiation, indicating that the fill factor limitation is linked to the initial Zn(O,S) growth on the modified CIGS-KF surface. The best CIGS-KF/Zn (O,S) devices were fabricated by etching away the KF-modified surface layer prior to ALD, followed by a low temperature anneal. The thermal treatment step is needed to increase the open-circuit voltage close to the value of the CdS devices. The results presented in this contribution indicate that the main beneficial effects from KFPDT in our devices are neither associated with the CdS CBD process nor due to the formation of a K-In-Serich phase on the CIGS surface.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
CIGS, KF-PDT, Zinc oxysulfide, Buffer layers, Interfaces
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-358259 (URN)10.1016/j.solmat.2018.03.045 (DOI)000435624400002 ()
Funder
Swedish Energy Agency, 2017-004796
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-27Bibliographically approved
Donzel-Gargand, O., Thersleff, T., Keller, J., Törndahl, T., Larsson, F., Wallin, E., . . . Edoff, M. (2018). Deep surface Cu depletion induced by K in high-efficiency Cu(In,Ga)Se2 solar cell absorbers. Progress in Photovoltaics, 26(9), 730-739
Open this publication in new window or tab >>Deep surface Cu depletion induced by K in high-efficiency Cu(In,Ga)Se2 solar cell absorbers
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2018 (English)In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 26, no 9, p. 730-739Article in journal (Refereed) Published
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.

Keywords
CIGS, Cu depletion, EELS, OVC, Raman, solar cell, TEM
National Category
Other Materials Engineering Energy Systems
Identifiers
urn:nbn:se:uu:diva-357120 (URN)10.1002/pip.3010 (DOI)000442501000004 ()
Funder
Swedish Research CouncilSwedish Energy AgencyEU, Horizon 2020, 720887
Available from: 2018-08-12 Created: 2018-08-12 Last updated: 2018-11-13Bibliographically approved
Ledinek, D., Donzel-Gargand, O., Sköld, M., Keller, J. & Edoff, M. (2018). Effect of different Na supply methods on thin Cu(In,Ga)Se2 solar cells with Al2O3 rear passivation layers. Solar Energy Materials and Solar Cells, 187(1), 160-169
Open this publication in new window or tab >>Effect of different Na supply methods on thin Cu(In,Ga)Se2 solar cells with Al2O3 rear passivation layers
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2018 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 187, no 1, p. 160-169Article in journal (Refereed) Published
Abstract [en]

In this work, rear-contact passivated Cu(In,Ga)Se2 (CIGS) solar cells were fabricated without any intentional contact openings between the CIGS and Mo layers. The investigated samples were either Na free or one of two Na supply methods was used, i) a NaF precursor on top of the Al2O3 rear passivation layer or ii) an in situ post- deposition treatment with NaF after co-evaporation of the CIGS layer. The thickness of the ALD-Al2O3 passi- vation layer was also varied in order to find an optimal combination of Na supply and passivation layer thickness. Our results from electrical characterization show remarkably different solar cell behavior for different Na supplies. For up to 1nm thick Al2O3 layers an electronically good contact could be confirmed independently of Na deposition method and content. When the Al2O3 thickness exceeded 1 nm, the current was blocked on all samples except on the samples with the NaF precursor. On these samples the current was not blocked up to an Al2O3 layer thickness of about 6 nm, the maximum thickness we could achieve without the CIGS peeling off the Al2O3 layer. Transmission electron microscopy reveals a porous passivation layer for the samples with a NaF precursor. An analysis of the dependence of the open circuit voltage on temperature (JVT) indicates that a thicker NaF precursor layer lowers the height of the hole barrier at the rear contact for the passivated cells. This energy barrier is also lower for the passivated sample, compared to an unpassivated sample, when both samples have been post-deposition treated.

Keywords
Alkali, Back contact, CIGS, Passivation, Thin films, Rear contact, Tunneling
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Energy Systems Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-357123 (URN)10.1016/j.solmat.2018.07.017 (DOI)000445308300019 ()
Funder
Swedish Research Council, 43523-1StandUpEU, Horizon 2020, 720887
Available from: 2018-08-12 Created: 2018-08-12 Last updated: 2019-08-08Bibliographically approved
Donzel-Gargand, O. (2018). The Multiple Faces of Interfaces: Electron microscopy analysis of CuInSe2 thin-film solar cells. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>The Multiple Faces of Interfaces: Electron microscopy analysis of CuInSe2 thin-film solar cells
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The CIS solar cell family features both a high stability and world-class performances. They can be deposited on a wide variety of substrates and absorb the entire solar spectrum only using a thickness of a few micrometers. These particularities allow them to feature the most positive Energy returned on energy invested (EROI) values and the shortest Energy payback times (EPBT) of all the main photovoltaic solar cells. Using mainly electron microscopy characterization techniques, this thesis has explored the questions related to the interface control in thin-film photovoltaic solar cells based on CuInSe2 (CIS) absorber materials. Indeed, a better understanding of the interfaces is essential to further improve the solar cell conversion efficiency (currently around 23%), but also to introduce alternative substrates, to implement various alloying (Ga-CIS (CIGS), Ag-CIGS (ACIGS)…) or even to assess alternative buffer layers.

The thread of this work is the understanding and the improvement of the interface control. To do so, the passivation potential of Al2O3 interlayers has been studied in one part of the thesis. While positive changes were generally measured, a subsequent analysis has revealed that a detrimental interaction could occur between the NaF precursor layer and the rear Al2O3 passivation layer. Still within the passivation research field, incorporation of various alkali-metals to the CIS absorber layer has been developed and analyzed. Large beneficial effects were ordinarily reported. However, similar KF-post deposition treatments were shown to be potentially detrimental for the silver-alloyed CIGS absorber layer. Finally, part of this work dealt with the limitations of the thin-barrier layers usually employed when using steel substrates instead of soda-lime glass ones. The defects and their origin could have been related to the steel manufacturing process, which offered solutions to erase them.

Electron microscopy, especially Transmission electron microscopy (TEM), was essential to scrutinize the local changes occurring at the different interfaces within a few nanometers. The composition variation was measured with both Electron energy loss spectroscopy (EELS) and Energy dispersive X-ray spectroscopy (EDS) techniques. Finally, efforts have been invested in controlling and improving the FIB sample preparation, which was required for the TEM observations in our case.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 85
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1701
Keywords
Electron microscopy, TEM, STEM, EELS, EDS, solar cells, CIGS, ACIGS, CZTS, post deposition treatment, KF, RbF, buffer layers, interfaces, inter layers, barrier layers, passivation layers
National Category
Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering Other Materials Engineering
Research subject
Engineering Science with specialization in Materials Science; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-357127 (URN)978-91-513-0402-1 (ISBN)
Public defence
2018-09-28, Polhemssalen, The Angstrom laboratory, Lägerhyddsvägen 1, Uppsala, 09:30 (English)
Opponent
Supervisors
Available from: 2018-09-07 Created: 2018-08-12 Last updated: 2018-10-02
Englund, S., Grini, S., Donzel-Gargand, O., Paneta, V., Kosyak, V., Primetzhofer, D., . . . Platzer Björkman, C. (2018). TiN Interlayers with Varied Thickness in Cu2ZnSnS(e)(4) Thin Film Solar Cells: Effect on Na Diffusion, Back Contact Stability, and Performance. Physica Status Solidi (a) applications and materials science, 215(23), Article ID 1800491.
Open this publication in new window or tab >>TiN Interlayers with Varied Thickness in Cu2ZnSnS(e)(4) Thin Film Solar Cells: Effect on Na Diffusion, Back Contact Stability, and Performance
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2018 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 23, article id 1800491Article in journal (Refereed) Published
Abstract [en]

In this study, interlayers with varied thickness of TiN between Cu2ZnSnS(e)(4) (CZTS(e)) absorbers and Mo on soda-lime glass substrates are investigated for CZTS(e) thin film solar cells. Na diffusion is analyzed using Secondary Ion Mass Spectrometry and it is found that the use of thick TiN interlayers facilitates Na diffusion into the absorbers. The CZTS(e)/TiN/Mo interfaces are scrutinized using Transmission Electron Microscopy (TEM) Electron Energy Loss Spectroscopy (EELS). It is found that diffusion of chalcogens present in the precursor occurs through openings, resulting from surface roughness in the Mo, in the otherwise chemically stable TiN interlayers, forming point contacts of MoS(e)(2). It is further established that both chalcogens and Mo diffuse along the TiN interlayer grain boundaries. Solar cell performance for sulfur-annealed samples improved with increased thickness of TiN, and with a 200 nm TiN interlayer, the solar cell performance is comparable to a typical Mo reference. Pure TiN bulk contacts are investigated and shown to work, but the performance is still inferior to the TiN interlayer back contacts. The use of thick TiN interlayers offers a pathway to achieve high efficiency CZTS(e) solar cells on highly inert back contacts.

Keywords
back contacts, CZTS, interlayers, thin film solar cells, titanium nitride
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-372758 (URN)10.1002/pssa.201800491 (DOI)000452297400012 ()
Funder
Swedish Foundation for Strategic Research , FFL12-0178
Available from: 2019-01-15 Created: 2019-01-15 Last updated: 2019-01-15Bibliographically approved
Bilousov, O. V., Ren, Y., Törndahl, T., Donzel-Gargand, O., Ericson, T., Platzer Björkman, C., . . . Hägglund, C. (2017). ALD of phase controlled tin monosulfide thin films. In: : . Paper presented at Joint EuroCVD 21 – Baltic ALD 15.
Open this publication in new window or tab >>ALD of phase controlled tin monosulfide thin films
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2017 (English)Conference paper, Poster (with or without abstract) (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.

Keywords
atomic layer deposition, thin films, solar cells, semiconductors
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-335501 (URN)
Conference
Joint EuroCVD 21 – Baltic ALD 15
Projects
Ultrathin nanocomposite absorbers and heterojunctions for solar cells
Funder
Swedish Research Council, 621-2014-5599
Available from: 2017-12-06 Created: 2017-12-06 Last updated: 2017-12-29Bibliographically approved
Bilousov, O. V., Ren, Y., Törndahl, T., Donzel-Gargand, O., Ericson, T., Platzer-Björkman, C., . . . Hägglund, C. (2017). Atomic Layer Deposition of Cubic and Orthorhombic Phase Tin Monosulfide. Chemistry of Materials, 29(7), 2969-2978
Open this publication in new window or tab >>Atomic Layer Deposition of Cubic and Orthorhombic Phase Tin Monosulfide
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2017 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 7, p. 2969-2978Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-321836 (URN)10.1021/acs.chemmater.6b05323 (DOI)000399264100042 ()
Funder
Swedish Research Council, 621-2014-5599
Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2017-05-15Bibliographically approved
Englund, S., Paneta, V., Primetzhofer, D., Ren, Y., Donzel-Gargand, O., Larsen, J. K., . . . Platzer Björkman, C. (2017). Characterization of TiN back contact interlayers with varied thickness for Cu2ZnSn(S,Se)4 thin film solar cells. Thin Solid Films, 639, 91-97
Open this publication in new window or tab >>Characterization of TiN back contact interlayers with varied thickness for Cu2ZnSn(S,Se)4 thin film solar cells
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2017 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 639, p. 91-97Article in journal (Refereed) Published
Abstract [en]

TiN thin films have previously been used as intermediate barrier layers on Mo back contacts in CZTS(e) solar cells to suppress excessive reaction of the Mo in the annealing step. In this work, TiN films with various thickness (20, 50 and 200 nm) were prepared with reactive DC magnetron sputtering on Mo/SLG substrates and annealed, without CZTS(e) layers, in either S or Se atmospheres. The as-deposited references and the annealed samples were characterized with X-ray Photoelectron Spectroscopy, X-ray Diffraction, Time-of-Flight-Elastic Recoil Detection Analysis, Time-of-Flight-Medium-Energy Ion Scattering, Scanning Electron Microscopy and Scanning Transmission Electron Microscopy – Electron Energy Loss Spectroscopy. It was found that the as-deposited TiN layers below 50 nm show discontinuities, which could be related to the surface roughness of the Mo. Upon annealing, TiN layers dramatically reduced the formation of MoS(e)2, but did not prevent the sulfurization or selenization of Mo. The MoS(e)2 had formed near the discontinuities, both below and above the TiN layers. Another unexpected finding was that the thicker TiN layer increased the amount of Na diffused to the surface after anneal, and we suggest that this effect is related to the Na affinity of the TiN layers and the MoS(e)2 thickness.

Keywords
Molybdenum, Titanium nitride, Interlayer, Back contact, Sulfurization, Selenization, CZTS, Thin film solar cell
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-335799 (URN)10.1016/j.tsf.2017.08.030 (DOI)000412787200014 ()
Funder
Swedish Foundation for Strategic Research , FFL12-0178
Available from: 2017-12-08 Created: 2017-12-08 Last updated: 2018-01-10Bibliographically approved
Donzel-Gargand, O., Thersleff, T., Keller, J., Törndahl, T., Larsson, F., Wallin, E., . . . Edoff, M. (2017). Cu-depleted patches induced by presence of K during growth of CIGS absorbers. In: : . Paper presented at 34th European PV Solar Energy Conference and Exhibition (EUPVSEC) 2017.
Open this publication in new window or tab >>Cu-depleted patches induced by presence of K during growth of CIGS absorbers
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2017 (English)Conference paper, Oral presentation with published abstract (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.

National Category
Energy Systems Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-335110 (URN)
Conference
34th European PV Solar Energy Conference and Exhibition (EUPVSEC) 2017
Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2017-12-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2101-3746

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