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Composition Engineering of All‐Inorganic Perovskite Film for Efficient and Operationally Stable Solar Cells
Author(s) -
Tian Jingjing,
Wang Jing,
Xue Qifan,
Niu Tianqi,
Yan Lei,
Zhu Zonglong,
Li Ning,
Brabec Christoph J.,
Yip HinLap,
Cao Yong
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202001764
Subject(s) - materials science , passivation , perovskite (structure) , energy conversion efficiency , crystallization , photovoltaic system , grain boundary , grain size , solar cell , crystal (programming language) , nucleation , chemical engineering , nanotechnology , optoelectronics , microstructure , composite material , layer (electronics) , electrical engineering , chemistry , organic chemistry , computer science , engineering , programming language
Cesium‐based inorganic perovskites have recently attracted great research focus due to their excellent optoelectronic properties and thermal stability. However, the operational instability of all‐inorganic perovskites is still a main hindrance for the commercialization. Herein, a facile approach is reported to simultaneously enhance both the efficiency and long‐term stability for all‐inorganic CsPbI 2.5 Br 0.5 perovskite solar cells via inducing excess lead iodide (PbI 2 ) into the precursors. Comprehensive film and device characterizations are conducted to study the influences of excess PbI 2 on the crystal quality, passivation effect, charge dynamics, and photovoltaic performance. It is found that excess PbI 2 improves the crystallization process, producing high‐quality CsPbI 2.5 Br 0.5 films with enlarged grain sizes, enhanced crystal orientation, and unchanged phase composition. The residual PbI 2 at the grain boundaries also provides a passivation effect, which improves the optoelectronic properties and charge collection property in optimized devices, leading to a power conversion efficiency up to 17.1% with a high open‐circuit voltage of 1.25 V. More importantly, a remarkable long‐term operational stability is also achieved for the optimized CsPbI 2.5 Br 0.5 solar cells, with less than 24% degradation drop at the maximum power point under continuous illumination for 420 h.