Stabilization of Highly Efficient and Stable Phase-Pure FAPbI3 Perovskite Solar Cells by Molecularly Tailored 2D-Overlayers |
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| Authors: | Dr Yuhang Liu Dr Seckin Akin Dr Alexander Hinderhofer Dr Felix T Eickemeyer Hongwei Zhu Dr Ji-Youn Seo Jiahuan Zhang Prof Frank Schreiber Dr Hong Zhang Dr Shaik M Zakeeruddin Prof Anders Hagfeldt Dr M Ibrahim Dar Prof Michael Grätzel |
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| Institution: | 1. Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;2. Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany;3. Laboratory of Photomolecular Science, École Polytechnique Fédérale de Lausanne, Station 6, 1015 Lausanne, Switzerland |
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| Abstract: | As a result of their attractive optoelectronic properties, metal halide APbI3 perovskites employing formamidinium (FA+) as the A cation are the focus of research. The superior chemical and thermal stability of FA+ cations makes α-FAPbI3 more suitable for solar-cell applications than methylammonium lead iodide (MAPbI3). However, its spontaneous conversion into the yellow non-perovskite phase (δ-FAPbI3) under ambient conditions poses a serious challenge for practical applications. Herein, we report on the stabilization of the desired α-FAPbI3 perovskite phase by protecting it with a two-dimensional (2D) IBA2FAPb2I7 (IBA=iso-butylammonium overlayer, formed via stepwise annealing. The α-FAPbI3/IBA2FAPb2I7 based perovskite solar cell (PSC) reached a high power conversion efficiency (PCE) of close to 23 %. In addition, it showed excellent operational stability, retaining around 85 % of its initial efficiency under severe combined heat and light stress, that is, simultaneous exposure with maximum power tracking to full simulated sunlight at 80 °C over 500 h. |
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| Keywords: | additive engineering FAPbI3 perovskite solar cells thermal stability |
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