A Review on Stability of Inorganic Metal Halide Perovskites: Challenge and Opportunity for Stable Solar Cells
Inorganic perovskite based solar cells (PSCs) have been receiving unprecedented attention worldwide in the past several years due to their higher intrinsic stability towards high temperature and high theoretical power conversion efficiency. Since a photovoltaic performance of 20.37% has been achieved for inorganic PSCs recently, the operational stability of these devices has become the major bottleneck which impedes the commercialization of this technology. The high thermal stability associated with inorganic perovskites comes along with poorer phase stability compared to the hybrid counterparts and therefore needs thorough understanding. Lattice strain and vacancies within the perovskite crystals are found to be the origins for these phase instabilities. This review summarizes the progress of stability research on inorganic perovskites. Specifically, the degradation mechanisms of inorganic perovskites towards temperature, moisture and oxygen are summarized and discussed. Solutions for tackling these stability issues are reviewed and an outlook on further strategies is given.