Low-Temperature Aging Provides 22% Efficient Bromine-Free and Passivation Layer-Free Planar Perovskite Solar Cells

Xin Wang; Luyao Wang; Tong Shan; Shibing Leng; Hongliang Zhong; Qinye Bao; Zheng-Hong Lu; Lin-Long Deng; Chun-Chao Chen

doi:10.1007/s40820-020-00418-0

Low-Temperature Aging Provides 22% Efficient Bromine-Free and Passivation Layer-Free Planar Perovskite Solar Cells

Nanomicro Lett. 2020 Apr 3;12(1):84. doi: 10.1007/s40820-020-00418-0.

Authors

Xin Wang¹, Luyao Wang¹, Tong Shan², Shibing Leng¹, Hongliang Zhong², Qinye Bao³, Zheng-Hong Lu⁴, Lin-Long Deng⁵, Chun-Chao Chen⁶

Affiliations

¹ School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
² School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
³ Key Laboratory of Solar Materials and Devices, Department of Electronic Science, School of Physics and Electronic Science, East China Normal University, Shanghai, 200240, People's Republic of China.
⁴ Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, ON, M5S 3E4, Canada. zhenghong.lu@utoronto.ca.
⁵ Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, People's Republic of China. denglinlong@xmu.edu.cn.
⁶ School of Material Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China. c3chen@sjtu.edu.cn.

Abstract

Previous reports of formamidinium/methylamine (FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface-for example, through the inclusion of bromine and surface passivation. In this paper, we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI₃ halide perovskites via the control of intermediate phase. Through low-temperature aging growth (LTAG) of a freshly deposited perovskite film, α-phase perovskites can be seeded in the intermediate phase and, at the same time, prevent beta-phase perovskite to nucleate. After postannealing, large grain-size perovskites with significantly reduced PbI₂ presence on the surface can be obtained, thereby eliminating the need of additional surface passivation step. Our pristine LTAG-treated solar cells could provide PCEs of greater than 22% without elaborate use of bromine or an additional passivation layer. More importantly, when using this LTAG process, the growth of the pure alpha-phase FAMAPbI₃ was highly reproducible.

Keywords: Aging growth; Bromine-free; Lead iodide; Passivation layer; Perovskite solar cells.