A Thermodynamically Favored Crystal Orientation in Mixed Formamidinium/Methylammonium Perovskite for Efficient Solar Cells

• DOI: 10.1002/adma.201900390
• Publication Date: 2019-04-23T06:03:51Z
• Authors: Ziqi Xu; Zonghao Liu; Nengxu Li; Gang Tang; Guanhaojie Zheng; Cheng Zhu; Yihua Chen; Ligang Wang; Yuan Huang; Liang Li; Ning Zhou; Jiawang Hong; Qi Chen; Huanping Zhou
• Keywords: Formamidinium; Crystal (programming language); Trihalide; Crystal Engineering

Crystal orientation has a great impact on the properties of perovskite films and resultant device performance. Up to now, exquisite control crystal (the preferred crystallographic planes stacking mode with respect particular planes) in mixed-cation perovskites received limited success, underlying mechanism that governs performance is still not clear. Here, thermodynamically favored formamidinium/methylammonium (FA/MA) finely tuned by composition engineering. Density functional theory calculations reveal FA/MA ratio affects surface energy mixed perovskites, leading variation preferential consequently. The preferable growth along (001) plane, when lying parallel substrates, their charge transportation collection properties. Under optimized condition, (FA1-x MAx PbI2.87 Br0.13 (Cl)) solar cells deliver champion power conversion efficiency over 21%, certified 20.50 ± 0.50%. present work only provides vital step understanding intrinsic but also lays foundation for further investigation application optoelectronics.