The effect on the optoelectronic properties and charge carrier dynamics in halide perovskites due to lattice expansion*

Halide perovskites undergo structural expansion when exposed to various stimuli. This expansion affects their electronic properties and charge carrier dynamics. It is essential to atomistically model how geometric changes modify the electronic characteristics important for applications such as light harvesting. We use ab initio simulations to investigate the optical and electronic properties of FAPbI₃ under tensile strain. The applied strain leads to elongation of the Pb–I bonds and a decrease in PbI₆ octahedral tilting, which manifests as a blue-shift in the band gap. Nonadiabatic molecular dynamics simulations reveal that charge carrier recombination rates are moderately decreased in these expanded lattices. The influence of lattice dynamics on electron–phonon scattering results in a longer carrier lifetime, which is advantageous for efficient solar cells. By providing detailed information about structure–property relationships, this work emphasizes the role of controlled lattice expansion in enhancing the electronic functionalities of halide perovskites.