A New Descriptor for Complicated Effects of Electronic Density of States on Ion Migration

摘要

Halide perovskites have attracted much attention because of their excellentoptoelectronic properties, such as high light absorption, long carrier diffusionlength, and high defect tolerance. Ion migration induced device performancedegradation, which is not yet fully understood, has become the key obstaclefor commercialization of halide perovskites. Here, a general mechanism isproposed, which can build up the connection between the ion migration barrierand the electronic density of states, to clarify the origin of low barrier forion migration. Density functional theory (DFT) simulation results show thatthe low barrier is caused by a significant energy difference in band centersbetween Pb~（2+） and the isolating halogen anion or by the small number of densityof states. Following the explored mechanism, two strategies are proposedto boost barriers via DFT combination CI-NEB simulations: 1) halide doubleperovskites and 2) B-site doping. Furthermore, the finding not only deepensthe understanding of ion migration in halide perovskites but also paves a newpath for the commercialization of halide perovskite optoelectronic devices.