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A Thermodynamically Favored Crystal Orientation in Mixed Formamidinium/Methylammonium Perovskite for Efficient Solar Cells
Author(s) -
Xu Ziqi,
Liu Zonghao,
Li Nengxu,
Tang Gang,
Zheng Guanhaojie,
Zhu Cheng,
Chen Yihua,
Wang Ligang,
Huang Yuan,
Li Liang,
Zhou Ning,
Hong Jiawang,
Chen Qi,
Zhou Huanping
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201900390
Subject(s) - formamidinium , perovskite (structure) , materials science , crystal (programming language) , trihalide , stacking , crystal engineering , density functional theory , crystallography , energy conversion efficiency , chemical physics , crystal structure , nanotechnology , optoelectronics , inorganic chemistry , computational chemistry , chemistry , organic chemistry , supramolecular chemistry , halide , computer science , programming language
Crystal orientation has a great impact on the properties of perovskite films and the resultant device performance. Up to now, the exquisite control of crystal orientation (the preferred crystallographic planes and the crystal stacking mode with respect to the particular planes) in mixed‐cation perovskites has received limited success, and the underlying mechanism that governs device performance is still not clear. Here, a thermodynamically favored crystal orientation in formamidinium/methylammonium (FA/MA) mixed‐cation perovskites is finely tuned by composition engineering. Density functional theory calculations reveal that the FA/MA ratio affects the surface energy of the mixed perovskites, leading to the variation of preferential orientation consequently. The preferable growth along the (001) crystal plane, when lying parallel to the substrates, affects their charge transportation and collection properties. Under the optimized condition, the mixed‐cation perovskite (FA 1– x MA x PbI 2.87 Br 0.13 (Cl)) solar cells deliver a champion power conversion efficiency over 21%, with a certified efficiency of 20.50 ± 0.50%. The present work not only provides a vital step in understanding the intrinsic properties of mixed‐cation perovskites but also lays the foundation for further investigation and application in perovskite optoelectronics.