Chemical passivation of methylammonium fragments eliminates traps,extends charge lifetimes,and restores structural stability of CH_(3)NH_(3)PbI_(3) perovskite  

作　　者：Xi Zhao Wei-Hai Fang Run Long Oleg V.Prezhdo 

机构地区：[1]College of Chemistry,Key Laboratory of Theoretical&Computational Photochemistry of Ministry of Education,Beijing Normal University,Beijing 100875,China [2]Department of Chemistry,University of Southern California,Los Angeles,California 90089,USA

出　　处：《Nano Research》2022年第5期4765-4772,共8页纳米研究（英文版）

基　　金：This work was supported by the Beijing Natural Science Foundation(No.2212031);the National Natural Science Foundation of China(Nos.21973006,51861135101,and 21520102005);R.L.acknowledges the financial support by the Recruitment Program of Global Youth Experts of China and the Beijing Normal University Startup.O.V.P.acknowledges the support of the US Department of Energy(No.DE-SC0014429).

摘　　要：Hybrid organic-inorganic perovskites are currently considered the most promising next-generation photovoltaic material.However,poor stability,arising from structural degradation under exposure to moisture,heat,and strong current,remains a critical challenge for their device applications.Using ab initio nonadiabatic molecular dynamics,we demonstrate that methylamine fragments deriving from the dissociation of the methylammonium cation can undermine structural stability,produce deep hole traps,and decrease charge carrier lifetimes by 1-3 orders of magnitude.Both stability and charge lifetime can be restored by methylamine passivation with chlorines,which withdraw electrons from the lone electron pair of methylamine and bring the trap levels down into the valence band.The charge lifetime of the passivated system is even longer than that of the pristine perovskite.The simulations reveal the detailed microscopic mechanism underlying deterioration of perovskite performance due to molecular defects,and demonstrate an effective defect passivation strategy to obtain highly efficient and stable perovskite solar cells.

关 键 词：hybrid organic-inorganic perovskites structural stability methylammonium dissociation chlorine passivation time-domain density functional theory nonadiabati cmolecular dynamics 

分 类 号：O64[理学—物理化学]