Lattice Expansion in Hybrid Perovskites: Effect on Optoelectronic Properties and Charge Carrier Dynamics.

Hybrid halide perovskites frequently undergo structural expansion due to various stimuli, significantly affecting their electronic properties and in particular their charge carrier dynamics. It is essential to atomistically model how geometric changes modify electronic characteristics that are important for applications such as light harvesting and lighting. Using ab initio simulations, here we investigate the structural dynamics and optoelectronic properties of FAPbI3 under tensile strain. The applied strain leads to elongation of the Pb-I bonds and a decrease in the level of PbI6 octahedral tilting, which manifests as blue-shifts in band gaps. Nonadiabatic molecular dynamics simulations further reveal that charge carrier recombination rates moderately decrease in these expanded lattices. The complex 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 the structure-property relationships, this work emphasizes the role of controlled lattice expansion in enhancing the electronic functionalities of hybrid perovskites.