Volume 19, Issue 11 p. 1363-1370
Article

Planar Perovskite Solar Cells with High Open-Circuit Voltage Containing a Supramolecular Iron Complex as Hole Transport Material Dopant

Yasemin Saygili

Yasemin Saygili

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

These authors contributed equally to this work

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Silver-Hamill Turren-Cruz

Silver-Hamill Turren-Cruz

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

Benemérita Universidad Autónoma de Puebla., CIDS, Av. San Claudio y 18 Sur, Col. San Manuel, Ciudad Universitaria, CP 72570, P.O. Box 1067, Puebla, Pue., 7200 México

These authors contributed equally to this work

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Dr. Selina Olthof

Dr. Selina Olthof

Department of Chemistry, University of Cologne, Luxemburger Straße 116, 50939 Cologne, Germany

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Bartholomeus Wilhelmus Henricus Saes

Bartholomeus Wilhelmus Henricus Saes

Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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Dr. Ilknur Bayrak Pehlivan

Dr. Ilknur Bayrak Pehlivan

Department of Engineering Sciences, Solid State Physics, Uppsala University, Box 534, SE, 751 21 Uppsala, Sweden

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Dr. Michael Saliba

Dr. Michael Saliba

Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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Prof. Dr. Klaus Meerholz

Prof. Dr. Klaus Meerholz

Department of Chemistry, University of Cologne, Luxemburger Straße 116, 50939 Cologne, Germany

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Prof. Tomas Edvinsson

Prof. Tomas Edvinsson

Department of Engineering Sciences, Solid State Physics, Uppsala University, Box 534, SE, 751 21 Uppsala, Sweden

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Dr. Shaik M. Zakeeruddin

Dr. Shaik M. Zakeeruddin

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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Prof. Dr. Michael Grätzel

Prof. Dr. Michael Grätzel

Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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Dr. Juan-Pablo Correa-Baena

Dr. Juan-Pablo Correa-Baena

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

Current Address: Massachusetts Institute of Technology, Cambridge, MA, USA, 02139

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Prof. Anders Hagfeldt

Corresponding Author

Prof. Anders Hagfeldt

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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Dr. Marina Freitag

Corresponding Author

Dr. Marina Freitag

Department of Chemistry– Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden

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Dr. Wolfgang Tress

Corresponding Author

Dr. Wolfgang Tress

Laboratory of Photomolecular Science, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

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First published: 26 April 2018
Citations: 17

Graphical Abstract

A supramolecular iron complex is synthesized as dopant for the hole transport material spiro-MeOTAD. Employing this material in planar perovskite solar cells, the authors achieve a remarkable open-circuit voltage larger than 1.2 V at 1 sun and 1.27 V at 3 suns. This work contributes to engineering and minimizing the charge-carrier recombination at the interface between perovskite and hole transport layer.

Abstract

In perovskite solar cells (PSCs), the most commonly used hole transport material (HTM) is spiro-OMeTAD, which is typically doped by metalorganic complexes, for example, based on Co, to improve charge transport properties and thereby enhance the photovoltaic performance of the device. In this study, we report a new hemicage-structured iron complex, 1,3,5-tris(5′-methyl-2,2′-bipyridin-5-yl)ethylbenzene Fe(III)-tris(bis(trifluoromethylsulfonyl)imide), as a p-type dopant for spiro-OMeTAD. The formal redox potential of this compound was measured as 1.29 V vs. the standard hydrogen electrode, which is slightly (20 mV) more positive than that of the commercial cobalt dopant FK209. Photoelectron spectroscopy measurements confirm that the iron complex acts as an efficient p-dopant, as evidenced in an increase of the spiro-OMeTAD work function. When fabricating planar PSCs with the HTM spiro-OMeTAD doped by 5 mol % of the iron complex, a power conversion efficiency of 19.5 % (AM 1.5G, 100 mW cm−2) is achieved, compared to 19.3 % for reference devices with FK209. Open circuit voltages exceeding 1.2 V at 1 sun and reaching 1.27 V at 3 suns indicate that recombination at the perovskite/HTM interface is low when employing this iron complex. This work contributes to recent endeavors to reduce recombination losses in perovskite solar cells.

Conflict of interest

The authors declare no conflict of interest.