Stabilizing Bottom Side of Perovskite via Preburying Cesium Formate toward Efficient and Stable Solar Cells |
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Authors: | Liangliang Deng Haoliang Wang Saqib Rafique Yanyan Wang Tianxiang Hu Kai Liu Yaxin Wang Xiaoguo Li Zuoti Xie Jun Tang Zhe Liu Jinpeng Li Wei Yuan Jiao Wang Anran Yu Yiqiang Zhan |
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Affiliation: | 1. Center of Micro-Nano System, School of Information Science and Technology, Fudan University, Shanghai, 200438 China;2. Department of Materials Science and Engineering, MATEC, Guangdong Technion—Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong, 515063 China;3. Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing, 100044 China;4. School of Optics and Photonics, Beijing Institute of Technology, Beijing, 100081 China;5. Institute of Optoelectronics, Fudan University, 2005 Songhu Road, Shanghai, 200438 China |
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Abstract: | The fragile bottom side of perovskite films is demonstrated to be harmful to the efficiency and stability of perovskite solar cells (PSCs) because the carrier extraction and recombination can be significantly influenced by the easily formed strain, voids, and defects on the bottom side. Nevertheless, the bottom side of perovskite films is usually overlooked because it remains a challenge to directly characterize and modify the bottom side. Herein, a facile and effective strategy is reported to stabilize the bottom side via preburying cesium formate (CsFo) into the SnO2 electron transport layer (ETL). It is found that the synergistic effect of cesium cation (Cs+) and formate anion (HCOO−) causes strain relaxation, void elimination, and defects’ reduction, which further facilitate the charge extraction. Consequently, the champion power conversion efficiency (PCE) of formamidinium (FA)-based PSCs is increased from 23.34% to 24.50%. Meanwhile, the ultraviolet (UV), thermal, and operational stability are also enhanced. Finally, formamidinium–cesium (FACs)-based PSCs are investigated to confirm the effectiveness of this preburied CsFo strategy, and the optimal device exhibits a champion PCE of 25.03% and a remarkably high fill factor (FF) of 85.65%. |
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Keywords: | bottom side cesium formate operational stability perovskite solar cells strains |
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