Homogenizing out-of-plane cation composition in perovskite solar cells
Zheng Liang, Yong Zhang, Huifen Xu, Wenjing Chen, Boyuan Liu, Jiyao Zhang, Hui Zhang, Zihan Wang, Dong‐Ho Kang, Jianrong Zeng, Xingyu Gao, Qisheng Wang, Huijie Hu, Hongmin Zhou, Xiangbin Cai, Xingyou Tian, Peter Reiß, Baomin Xu, Thomas Kirchartz, Zhengguo Xiao, Songyuan Dai, Nam‐Gyu Park, Jiajiu Ye, Xu Pan
Abstract
Abstract Perovskite solar cells with the formula FA 1− x Cs x PbI 3 , where FA is formamidinium, provide an attractive option for integrating high efficiency, durable stability and compatibility with scaled-up fabrication. Despite the incorporation of Cs cations, which could potentially enable a perfect perovskite lattice 1,2 , the compositional inhomogeneity caused by A-site cation segregation is likely to be detrimental to the photovoltaic performance of the solar cells 3,4 . Here we visualized the out-of-plane compositional inhomogeneity along the vertical direction across perovskite films and identified the underlying reasons for the inhomogeneity and its potential impact for devices. We devised a strategy using 1-(phenylsulfonyl)pyrrole to homogenize the distribution of cation composition in perovskite films. The resultant p–i–n devices yielded a certified steady-state photon-to-electron conversion efficiency of 25.2% and durable stability.