Proceedings of nanoGe International Conference on Perovskite Solar Cells, Photonics and Optoelectronics (NIPHO19)
DOI: https://doi.org/10.29363/nanoge.nipho.2019.039
Publication date: 21st November 2018
In this work, we consider the Br vacancy (VBr) in cesium lead bromide (CsPbBr3) as a prototype for the impact of structural dynamics on defect energetics in halide perovskites (HaPs). Using first principles molecular dynamics based on density functional theory, we find that the static picture of defect energetics breaks down; the energy of the VBr level is found to be intrinsically dynamic, oscillating by as much as 1 eV on the ps time scale at room temperature. These significant energy fluctuations are found to be correlated with the distance between the neighboring Pb atoms across the vacancy and with the electrostatic potential at their atomic sites. The unusually strong coupling of structural dynamics and defect energetics bears important implications for both experimental and theoretical analysis of defect characteristics in HaPs. Furthermore, it may hold significant ramifications for carrier transport and defect tolerance in this important class of photovoltaic materials.