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Efficient and Stable CsPbI 3 Solar Cells via Regulating Lattice Distortion with Surface Organic Terminal Groups
Author(s) -
Wu Tianhao,
Wang Yanbo,
Dai Zhensheng,
Cui Danyu,
Wang Tao,
Meng Xiangyue,
Bi Enbing,
Yang Xudong,
Han Liyuan
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.201900605
Subject(s) - materials science , perovskite (structure) , steric effects , energy conversion efficiency , octahedron , orthorhombic crystal system , density functional theory , band gap , iodide , phase transition , passivation , crystallography , chemical physics , nanotechnology , crystal structure , optoelectronics , inorganic chemistry , condensed matter physics , computational chemistry , layer (electronics) , stereochemistry , chemistry , physics
All‐inorganic cesium lead iodide perovskites (CsPbI 3 ) are promising wide‐bandgap materials for use in the perovskite/silicon tandem solar cells, but they easily undergo a phase transition from a cubic black phase to an orthorhombic yellow phase under ambient conditions. It is shown that this phase transition is triggered by moisture that causes distortion of the corner‐sharing octahedral framework ([PbI 6 ] 4− ). Here, a novel strategy to suppress the octahedral tilting of [PbI 6 ] 4− units in cubic CsPbI 3 by systematically controlling the steric hindrance of surface organic terminal groups is provided. This steric hindrance effectively prevents the lattice distortion and thus increases the energy barrier for phase transition. This mechanism is verified by X‐ray diffraction measurements and density functional theory calculations. Meanwhile, the formation of an organic capping layer can also passivate the surface electronic trap states of perovskite absorber. These modifications contribute to a stable power conversion efficiency (PCE) of 13.2% for the inverted planar perovskite solar cells (PSCs), which is the highest efficiency achieved by the inverted‐structure inorganic PSCs. More importantly, the optimized devices retained 85% of their initial PCE after aging under ambient conditions for 30 days.