How Hole Injection Accelerates Both Ion Migration and Nonradiative Recombination in Metal Halide Perovskites

Ion migration, hole trapping, and electron-hole recombination arecommon processes in metal halide perovskites. We demonstrate using ab initio non-adiabatic molecular dynamics and time-domain density functional theory that theyare intricately related and strongly influence each other. The hole injectionaccelerates ion migration by decreasing the diffusion barrier and shortening themigration length. The injected hole also promotes the nonradiative chargerecombination by strengthening electron-phonon interactions in the low-frequencyregion and prolonging the quantum coherence time. The synergy stems from the softperovskite lattice and response of the valence band maximum to the Pb-I latticedistortion induced by the hole. This work provides important insights into theinfluence of ion mobility and hole injection on the performance of perovskite solarcells and suggests that high concentration of holes should be avoided.