Time-Domain ab Initio Analysis Rationalizes the Unusual Temperature Dependence of Charge Carrier Relaxation in Lead Halide Perovskite

Increased charge carrier lifetimes at elevated temperatures constitute an intriguing and valuable feature of hybrid organic–inorganic perovskites that are subject to heating in solar energy applications. We rationalize this peculiar behavior at the atomistic level using real-time time-dependent density functional theory and nonadiabatic molecular dynamics. Focusing on tetragonal MAPbI3, we demonstrate that temperature has different effects on the organic and inorganic subsystems and leads to subtle structural changes, decreasing nonradiative electron–hole recombination. First, charge–phonon interactions are decreased because the libration dynamics of the organic component at higher temperature reduces the oscillation amplitude of the Pb–I lattice that supports electrons and holes. Second, thermal disorder localizes wave functions, reducing the nonadiabatic charge–phonon coupling. Third, tilting of the inorganic octahedra increases the bandgap, extending charge carrier lifetime further. The detailed time-domain atomistic analysis of the uncommon dependence of charge recombination on temperature emphasizes the key role played by the organic cation, establishes important structure–property relationships, provides valuable insights into efficient performance of perovskite solar cells, and highlights factors required to maintain and improve such performance.