Defect properties of the two-dimensional (CH3NH3)2Pb(SCN)2I2 perovskite: a density-functional theory study.
Recently, solar cells based on 2D (CH3NH3)2Pb(SCN)2I2 perovskite have realized a power conversion efficiency of 3.23%. In this work, we study the defect properties of (CH3NH3)2Pb(SCN)2I2 through density-functional theory calculations. It is found that the lower crystal structure dimensionality of (CH3NH3)2Pb(SCN)2I2 makes the valence band maximum lower and the conduction band minimum higher as compared to its 3D CH3NH3PbI3 perovskite counterpart, resulting in relatively deeper defect transition levels. Our calculated defect formation energies suggest that if the 2D (CH3NH3)2Pb(SCN)2I2 perovskite absorbers are synthesized under Pb-poor and I-rich conditions, the dominant defects should be Pb vacancies, which create shallow levels. The resultant perovskite films are expected to exhibit p-type conductivity with a relatively long carrier lifetime.
Department of Physics and Astronomy, and Wright Center for Photovoltaic Innovation and Commercialization, The University of Toledo, Toledo, Ohio 43606, USA. zewen.xiao@utoledo.edu yanfa.yan@utoledo.edu.
Zewen
Z
Xiao
Weiwei
W
Meng
Jianbo
J
Wang
Yanfa
Y
Yan