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Häggman, Leif
Alternative names
Publications (10 of 14) Show all publications
Nonomura, K., Vlachopoulos, N., Unger, E., Häggman, L., Hagfeldt, A. & Boschloo, G. (2019). Blocking the Charge Recombination with Diiodide Radicals by TiO2 Compact Layer in Dye-Sensitized Solar Cells. Journal of the Electrochemical Society, 166(9), B3203-B3208
Open this publication in new window or tab >>Blocking the Charge Recombination with Diiodide Radicals by TiO2 Compact Layer in Dye-Sensitized Solar Cells
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2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 9, p. B3203-B3208Article in journal (Refereed) Published
Abstract [en]

The addition of a compact titanium dioxide (TiO2) layer between the fluorine-doped tin oxide (FTO) coated glass substrate and the mesoporous TiO2 layer in the dye-sensitized solar cell (DSC) based on the iodide/triiodide redox couple (I-/I-3(-)) is known to improve its current-voltage characteristics. The compact layer decreases the recombination of electrons extracted through the FTO layer with I-3(-) around the maximum power point. Furthermore, the short-circuit photocurrent was improved, which previously has been attributed to the improved light transmittance and/or better contact between TiO2 and FTO. Here, we demonstrate that the compact TiO2 layer has another beneficial effect: it blocks the reaction between charge carriers in the FTO and photogenerated diiodide radical species (I-2(-center dot)). Using photomodulated voltammetry, it is demonstrated that the cathodic photocurrent found at bare FTO electrodes is blocked by the addition of a compact TiO2 layer, while the anodic photocurrent due to reaction with I-2(-center dot) is maintained.

Place, publisher, year, edition, pages
ELECTROCHEMICAL SOC INC, 2019
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-383838 (URN)10.1149/2.0281909jes (DOI)000466839800002 ()
Funder
Swedish Energy AgencySwedish Research Council, 2015-00163Knut and Alice Wallenberg Foundation
Available from: 2019-05-27 Created: 2019-05-27 Last updated: 2019-05-27Bibliographically approved
Zhang, X., Welch, K., Tian, L., Johansson, M. B., Häggman, L., Liu, J. & Johansson, E. M. (2017). Enhanced charge carrier extraction by a highly ordered wrinkled MgZnO thin film for colloidal quantum dot solar cells. Journal of Materials Chemistry C, 5(42), 11111-11120
Open this publication in new window or tab >>Enhanced charge carrier extraction by a highly ordered wrinkled MgZnO thin film for colloidal quantum dot solar cells
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2017 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 42, p. 11111-11120Article in journal (Refereed) Published
Abstract [en]

Efficient charge carrier extraction from a colloidal quantum dot (CQD) solid is crucial for highperformance of CQD solar cells (CQDSCs). Herein, highly ordered wrinkled MgZnO (MZO) thin films aredemonstrated to improve the charge carrier extraction of PbS CQDSCs. The highly ordered wrinkledMZO thin films are prepared using a low-temperature combustion method. The photovoltaicperformances of CQDSCs with a combustion-processed MZO (CP-MZO) thin film as an electrontransport material (ETM) are compared to those of CQDSCs with a conventional sol–gel processed MZO(SGP-MZO) thin film as an ETM. We performed photoluminescence quenching measurements of thecolloidal quantum dot (CQD) solid and charge carrier dynamic analysis of full solar cell devices. Theresults show that the highly ordered wrinkled CP-MZO thin film significantly increases the chargecarrier extraction from the CQD solid and therefore diminishes the charge interfacial recombination atthe CQD/ETM junction, leading to a 15.5% increase in power conversion efficiency. The improvedefficiency in the CP-MZO based CQDSC is also attributed to the compact and pin-hole free CP-MZOthin film.

National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-337927 (URN)10.1039/C7TC02740K (DOI)000414359500026 ()
Funder
Swedish Research CouncilSwedish Research Council FormasSwedish Energy AgencyGöran Gustafsson Foundation for Research in Natural Sciences and MedicineÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Available from: 2018-01-05 Created: 2018-01-05 Last updated: 2018-02-07Bibliographically approved
Jain, S. M., Qiu, Z., Häggman, L., Mirmohades, M., Johansson, M. B., Edvinsson, T. & Boschloo, G. (2016). Frustrated Lewis pair-mediated recrystallization of CH3NH3PbI3 for improved optoelectronic quality and high voltage planar perovskite solar cells. Energy & Environmental Science, 9(12), 3770-3782
Open this publication in new window or tab >>Frustrated Lewis pair-mediated recrystallization of CH3NH3PbI3 for improved optoelectronic quality and high voltage planar perovskite solar cells
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2016 (English)In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, no 12, p. 3770-3782Article in journal (Refereed) Published
Abstract [en]

Films of the hybrid lead halide perovskite CH3NH3PbI3 were found to react with pyridine vapor at room temperature leading to complete bleaching of the film. In dry air or nitrogen atmosphere recrystallization takes place, leading to perovskite films with markedly improved optical and photovoltaic properties. The physical and chemical origin of the reversible bleaching and recrystallization mechanism was investigated using a variety of experimental techniques and quantum chemical calculations. The strong Lewis base pyridine attacks the CH3NH3PbI3. The mechanism can be understood from a frustrated Lewis pair formation with a partial electron donation of the lone-pair on nitrogen together with competitive bonding to other species as revealed by Raman spectroscopy and DFT calculations. The bleached phase consists of methylammonium iodide crystals and an amorphous phase of PbI2( pyridine)(2). After spontaneous recrystallization the CH3NH3PbI3 thin films have remarkably improved photoluminescence, and solar cell performance increased from 9.5% for as-deposited films to more than 18% power conversion efficiency for recrystallized films in solar cells with planar geometry under AM1.5G illumination. Hysteresis was negligible and open-circuit potential was remarkably high, 1.15 V. The results show that complete recrystallization can be achieved with a simple room temperature pyridine vapor treatment of CH3NH3PbI3 films leading to high quality crystallinity films with drastically improved photovoltaic performance.

National Category
Physical Chemistry Engineering and Technology
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-311577 (URN)10.1039/c6ee02544g (DOI)000392915500017 ()
Funder
Swedish Energy AgencyStandUpSwedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyKnut and Alice Wallenberg Foundation
Available from: 2016-12-29 Created: 2016-12-29 Last updated: 2017-11-29Bibliographically approved
Safdari, M., Lohse, P. W., Häggman, L., Frykstrand, S., Högberg, D., Rutland, M., . . . Boschloo, G. (2016). Investigation of cobalt redox mediators and effects of TiO2 film topology in dye-sensitized solar cells. RSC Advances, 6(61), 56580-56588
Open this publication in new window or tab >>Investigation of cobalt redox mediators and effects of TiO2 film topology in dye-sensitized solar cells
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2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 61, p. 56580-56588Article in journal (Refereed) Published
Abstract [en]

One-electron outer-sphere redox couples, such as cobalt metal-organic complexes, represent an interesting alternative as redox mediators in dye-sensitized solar cells since they show weak visible light absorption and available redox potentials may lead to higher open circuit voltage values. Here, we have studied the effect of using different substituents on bipyridyl and phenanthroline ligands in cobalt redox shuttles, giving the following complexes: Co[tris(4,4'-dimethoxy-2,2'-bipyridine)(PF6)(2)], Co[tris(4,4'-dichloro-2,2'-bipyridine)(PF6)(2)] and Co[tris(4,7-dichloro-1,10-phenanthroline)(CF3SO3)(2)], displaying a range of CoII/CoIII redox potentials from +0.37 to +0.79 V vs. NHE. The regeneration kinetics of the organic dye D35 was found to depend systematically on the redox mediator potential, which was explained using Marcus theory. The mass transport of cobalt mediators in dye-sensitized solar cells is highly dependent on the porosity, effective surface area and roughness of the mesoporous TiO2 films. Therefore, films with different TiO2 pore sizes were prepared and investigated to gain an insight into the topological effects of TiO2 film preparation in order to obtain optimum solar cell performance.

National Category
Physical Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-299807 (URN)10.1039/c6ra07107d (DOI)000378275400108 ()
Funder
EU, European Research Council, 246124Swedish Energy AgencySwedish Research CouncilStandUp
Available from: 2016-07-27 Created: 2016-07-27 Last updated: 2017-11-28Bibliographically approved
Bagheri, N., Aghaei, A., Vlachopoulos, N., Skunik-Nuckowska, M., Kulesza, P. J., Häggman, L., . . . Hagfeldt, A. (2016). Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon. Electrochimica Acta, 194, 480-488
Open this publication in new window or tab >>Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon
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2016 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 194, p. 480-488Article in journal (Refereed) Published
Abstract [en]

The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three-and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g(-1) (at 0.1 A g(-1)). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell's energy and power densities as well. 

Keywords
battery-type material, double layer capacitance, nickel oxide, nickel oxide/activated carbon composite, charge capacity, two- and three-electrode configuration
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-288598 (URN)10.1016/j.electacta.2016.01.185 (DOI)000372523300054 ()
Funder
Swedish Energy AgencyStandUpSwedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2016-05-04 Created: 2016-04-28 Last updated: 2017-11-30Bibliographically approved
Bagheri, N., Aghaei, A., Ghotbi, M. Y., Marzbanrad, E., Vlachopoulos, N., Haggman, L., . . . Kulesza, P. J. J. (2014). Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell. Electrochimica Acta, 143, 390-397
Open this publication in new window or tab >>Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell
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2014 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 143, p. 390-397Article in journal (Refereed) Published
Abstract [en]

A dye-sensitized solar cell (DSC) based on the metal-free organic sensitizer and the cobalt (II, III) polypyridyl electrolyte was integrated here within an asymmetric supercapacitor utilizing cobalt-doped nickel oxide and activated carbon as positive and negative electrodes, respectively. A low cost nickel foil served as intermediate (auxiliary) bifunctional electrode separating two parts of the device and permitting the DSC electrolyte regeneration at one side and charge storage within cobalt-doped nickel oxide at the other. The main purpose of the research was to develop an integrated photocapacitor system capable of both energy generation and its further storage. Following irradiation at the 100 mW cm(-2) level, the solar cell generated an open-circuit voltage of 0.8 V and short-circuit current of 8 mA cm(-2) which corresponds to energy conversion efficiency of 4.9%. It was further shown that upon integration with asymmetric supercapacitor, the photogenerated energy was directly injected into porous charge storage electrodes thus resulting in specific capacitance of 32 F g(-1) and energy density of 2.3 Wh kg(-1). The coulumbic and total (energy conversion and charge storage) efficiency of photocapacitor were equal to 54% and 0.6%, respectively.

Keywords
dye-sensitized solar cell, cobalt (II, III) polypyridyl redox electrolyte, asymmetric supercapacitor, nickel oxide, integrated photocapacitor
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-237310 (URN)10.1016/j.electacta.2014.07.125 (DOI)000343626500049 ()
Available from: 2014-12-03 Created: 2014-12-01 Last updated: 2017-12-05Bibliographically approved
Zhang, J., Häggman, L., Jouini, M., Jarboui, A., Boschloo, G., Vlachopoulos, N. & Hagfeldt, A. (2014). Solid-State Dye-Sensitized Solar Cells Based on Poly( 3,4ethylenedioxypyrrole) and Metal-Free Organic Dyes. ChemPhysChem, 15(6), 1043-1047
Open this publication in new window or tab >>Solid-State Dye-Sensitized Solar Cells Based on Poly( 3,4ethylenedioxypyrrole) and Metal-Free Organic Dyes
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2014 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 15, no 6, p. 1043-1047Article in journal (Refereed) Published
Abstract [en]

Poly(3,4-ethylenedioxypyrrole) (PEDOP), combined with metal-free organic sensitizers, is efficiently used for the first time as the hole-transporting material in solid-state dye-sensitized solar cells. Devices employing PEDOP as the hole conductor and D35 or D21 L6 as the sensitizer show a ten-times-higher energy-conversion efficiency (of 4.5% and 3.3%, respectively) compared to Ru-Z907-based devices. This is due to the efficient suppression of electron recombination.

Keywords
dye-sensitized solar cells, electrochemistry, hole-transporting materials, organic sensitizers, photoelectrochemical polymerization
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-225021 (URN)10.1002/cphc.201301075 (DOI)000334080700008 ()
Available from: 2014-05-26 Created: 2014-05-26 Last updated: 2017-12-05Bibliographically approved
Skunik-Nuckowska, M., Grzejszczyk, K., Kulesza, P. J., Yang, L., Vlachopoulos, N., Häggman, L., . . . Hagfeldt, A. (2013). Integration of solid-state dye-sensitized solar cell with metal oxide charge storage material into photoelectrochemical capacitor. Journal of Power Sources, 234, 91-99
Open this publication in new window or tab >>Integration of solid-state dye-sensitized solar cell with metal oxide charge storage material into photoelectrochemical capacitor
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2013 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 234, p. 91-99Article in journal (Refereed) Published
Abstract [en]

A solid-state photo-rechargeable capacitor (photocapacitor) is obtained here by coupling a dye-sensitized solar cell and a ruthenium oxide based electrochemical capacitor. This integrated system permits direct storage of energy generated by sunlight within a single optoelectronic micro-electrochemical device. It utilizes three planar electrodes arranged sequentially to include a polymer hole conductor (poly-(3-hexylthiophene-2,5-diyl)), between the titanium oxide photoanode modified with dye (E)-3-(5-(4-(Bis(20,40-dibutoxybiphenyl-4-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid (D35) and the intermediate silver electrode as well as two hydrous ruthenium oxide layers (separated by protonically conducting Nafion (TM) membrane) between the intermediate (silver) and the external (counter) electrode. Upon integration of the capacitor and dye-sensitized solar cell into a single photocapacitor hybrid device, the following parameters were obtained under simulated 100 mW cm(-2) solar illumination: specific capacitance, 407 F g(-1) (3.26 F cm(-2)); energy and power densities, 0.17 mWh cm(-2) and 0.34 mW cm(-2) and coulombic efficiency, 88%. These data together with results of experiments performed at different light intensities (10-100 mW cm(-2)) are consistent with very good performance of the optoelectronic device under various light conditions.

Keywords
Photocapacitor, Dye-sensitized solar cell, Poly-(3-hexylthiophene-2, 5-diyl), Supercapacitor, Ruthenium oxide, Optoelectronics
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-199691 (URN)10.1016/j.jpowsour.2013.01.101 (DOI)000317151200011 ()
Available from: 2013-05-14 Created: 2013-05-13 Last updated: 2017-12-06Bibliographically approved
Yang, L., Zhang, J., Shen, Y., Park, B.-W., Bi, D., Häggman, L., . . . Jouini, M. (2013). New Approach for Preparation of Efficient Solid-State Dye-Sensitized Solar Cells by Photoelectrochemical Polymerization in Aqueous Micellar Solution. Journal of Physical Chemistry Letters, 4(23), 4026-4031
Open this publication in new window or tab >>New Approach for Preparation of Efficient Solid-State Dye-Sensitized Solar Cells by Photoelectrochemical Polymerization in Aqueous Micellar Solution
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2013 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, no 23, p. 4026-4031Article in journal (Refereed) Published
Abstract [en]

Hereby, we present a new, cost-effective, and environmentally friendly method of preparing an efficient solid-state dye-sensitized solar cell (sDSC) using a PEDOT conducting polymer as the hole conductor and a recently developed organic sensitizer. PEDOT is generated and deposited on the dye-sensitized TiO2 electrode by in situ photoelectropolymerization of bis-EDOT in aqueous micellar solution. The advantages of this approach are the use of water as the solvent and the obtainment of a sDSC simply by adding a silver layer on the as-obtained polymer film deposited on dye/TiO2 without the need for electrolytic solution. The sDSC containing the film prepared as above is compared to those where the organic dye is used to generate the same polymer film but in organic solvent. The energy conversion efficiency values of the two cells appear comparable, 4.8% for sDSC prepared in the aqueous-phase polymerized PEDOT and 6% for the sDSC prepared with in organic-phase polymerized PEDOT.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-214018 (URN)10.1021/jz4021266 (DOI)000328101000002 ()
Available from: 2014-01-08 Created: 2014-01-07 Last updated: 2017-12-06Bibliographically approved
Ellis, H., Vlachopoulos, N., Häggman, L., Perruchot, C., Jouini, M., Boschloo, G. & Hagfeldt, A. (2013). PEDOT counter electrodes for dye-sensitized solar cells prepared by aqueous micellar electrodeposition. Electrochimica Acta, 107, 45-51
Open this publication in new window or tab >>PEDOT counter electrodes for dye-sensitized solar cells prepared by aqueous micellar electrodeposition
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2013 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 107, p. 45-51Article in journal (Refereed) Published
Abstract [en]

Electropolymerization of 3,4-ethylenedioxythiophene (EDOT) was performed in an aqueous micellar solution onto conducting glass and conducting flexible plastic substrates using a simple, scalable process. The background electrolyte in the process consisted merely of a micellar aqueous sodium dodecyl sulfate (SDS) solution. Electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) was conducted at constant current, resulting in homogeneous films, even on large sized conducting glass and plastic substrates (9 cm x 9 cm). The use of water as electrolyte, application on large substrates and applicability on flexible plastic substrates demonstrates the feasibility of this method for upscaling and use in industrial fabrication of DSCs. DSCs were assembled using three different PEDOT thicknesses on conducting glass as counter electrodes and a comparison was made with thermally platinized conducting glass counter electrodes. In cobalt tris(bipyridine)-based electrolyte, the catalytic performance of the PEDOT counter electrodes was significantly higher than that of platinized counter electrodes. DSCs with PEDOT counter electrodes gave higher efficiencies due to higher fill factors and a lower charge transfer resistance. The low charge transfer resistance and good catalytic performance of the PEDOT counter electrodes can be related to its mesoporous morphology resembling crumpled sheets of paper. 

Keywords
Dye-sensitized solar cell, Electrocatalyst, Cobalt tris(bipyridine), Charge-transfer resistance, Nanostructured electrode
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-212422 (URN)10.1016/j.electacta.2013.06.005 (DOI)000326661200005 ()
Available from: 2013-12-10 Created: 2013-12-10 Last updated: 2017-12-06Bibliographically approved
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