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Passivating Detrimental DX Centers in CH 3 NH 3 PbI 3 for Reducing Nonradiative Recombination and Elongating Carrier Lifetime
Author(s) -
Wang Jing,
Li Wei,
Yin WanJian
Publication year - 2020
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.201906115
Subject(s) - passivation , materials science , carrier lifetime , perovskite (structure) , density functional theory , doping , semiconductor , chemical physics , solar cell , charge carrier , recombination , crystallographic defect , nanotechnology , optoelectronics , computational chemistry , crystallography , silicon , chemistry , biochemistry , layer (electronics) , gene
Abstract After a period of rapid, unprecedented development, the growth in the efficiency of perovskite solar cells has recently slowed. Further improvement of cell efficiency will rely on the in‐depth understanding and delicate control of defect passivation. Here, the formation mechanism of iodine vacancies (V I ), a typical deep defect in CH 3 NH 3 PbI 3 (MAPbI 3 ), is elucidated. The structural and electronic behaviors of V I are like those of a DX center, a kind of detrimental defect formed by large atomic displacement. Aided by the passivation mechanism of DX centers in tetrahedral semiconductors, it is found that the introduction of Br strengthens chemical bonds and prevents large atomic displacements during defect charging. It therefore reduces the defect states and diminishes electron–phonon coupling. Using time‐domain density functional theory (DFT) combined with nonadiabatic molecular dynamics, it is found that the carrier lifetime can be enhanced from 3.2 ns in defective MAPbI 3 to 19 ns in CH 3 NH 3 Pb(I 0.96 Br 0.04 ) 3 . This work advances our understanding of how a small amount of Br doping improves the carrier dynamics and cell performance of MAPbI 3 . It may also provide a route to enhance the carrier lifetimes and efficiencies of perovskite solar cells by defect passivation.