Surface in situ reconstruction of inorganic perovskite films enabling long carrier lifetimes and solar cells with 21% efficiency

• Published in: Nature energy Vol. 8; no. 4; pp. 372 - 380
• Main Authors: Chu, Xinbo, Ye, Qiufeng, Wang, Zhenhan, Zhang, Chen, Ma, Fei, Qu, Zihan, Zhao, Yang, Yin, Zhigang, Deng, Hui-Xiong, Zhang, Xingwang, You, Jingbi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2023; Nature Publishing Group
• Subjects: 639/301/1005/1007; 639/301/299; 639/301/299/946; Carrier lifetime; Cesium fluorides; Current carriers; Economics and Management; Efficiency; Energy; Energy gap; Energy loss; Energy Policy; Energy Storage; Energy Systems; Fluorine; Heterojunctions; Open circuit voltage; Perovskites; Photovoltaic cells; Photovoltaics; Radiative recombination; Reaction mechanisms; Recombination; Reconstruction; Renewable and Green Energy; Solar cells; Solar energy; Surface defects
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-023-01220-z

All-inorganic perovskites are emerging as excellent photovoltaic candidates for single-junction or tandem solar cells. However, large energy loss due to non-radiative recombination is the main constraint for performance enhancement. Accordingly, we developed a surface in situ reconstruction (SISR) strategy for inorganic perovskite by CsF treatment, which can suppress non-radiative recombination and promote hole extraction simultaneously. Surface defects can be effectively passivated by the introduced fluorine, and carrier lifetime was prolonged from 11.5 ns to 737.2 ns. In addition, a wider-bandgap perovskite layer can be generated as a graded heterojunction to facilitate hole extraction. The SISR reaction mechanism was also verified from both kinetic calculations and experiments. As a result, CsPbI x Br 3− x solar cell with SISR achieved an efficiency of 21.02% with a high open-circuit voltage of 1.27 V and fill factor of 85.3%. This work provides an effective approach to modulate inorganic perovskite surfaces for the design of efficient solar cells. Inorganic perovskite solar cells suffer from charge carrier losses. Chu et al. treat the perovskite surface with caesium fluoride, forming a wider-bandgap perovskite that increases the carrier lifetime and hole extraction efficiency.