Accelerated formation of iodine vacancies in CH3NH3PbI3 perovskites: The impact of oxygen and charges. Issue 4 (28th December 2022) - Li, Qihua
Abstract: Defects in CH3 NH3 PbI3 perovskites, oxygen species in the air, and local charges play a significant role in the long‐term stability of perovskites. However, the interplay of these factors are complex and their role in the degradation of perovskites at the atomistic level is not well understood. By using density functional theory calculations and chemical bonding analysis, we study the effect of oxygen and local charges on the degradation of perovskites. We find that the easier formation of I vacancies upon oxygen and the accelerated degradation of CH3 NH3 PbI3 by excess electrons via the formation of peroxide species. The creation of peroxide disintegrates the lattice of perovskites on the surfaces and possibly induces a cascade of degradation reactions that eventually destruct the perovskite lattices. We further demonstrate that the addition of holes are beneficial to prevent the formation of the peroxide, therefore can potentially improve the stability of the perovskites. Abstract : Oxygen plays an important role in the stability of CH3 NH3 PbI3 Perovskites. This article provides further understanding of the degradation of CH3 NH3 PbI3 induced by oxygen by accelerating the formation of Iodine vacancies, the deprotonation of CH3 NH3 + cation and the distortion of Pb‐I framework especially under the electron‐rich environment.