Optimizing Sublattice Correlation to Enhance Stability and Charge Carrier Lifetime in Mixed Halide Perovskites.

Wang, Jiao; Lu, Haoran; Tian, Xuesong; Long, Run; Prezhdo, Oleg V · Nano Lett · 2025

basic_science · Level V

Where this comes from

Abstract

A-site cations in ABX<sub>3</sub> metal halide perovskites do not contribute to the frontier electronic states. They influence optoelectronic properties indirectly through interaction with the BX<sub>3</sub> sublattice. By systematically investigating correlated motions of Cs cations and the PbX<sub>3</sub> lattice (X = Cl, Br, I), we demonstrate that the interaction between the two subsystems depends on electronegativity and size of the X-site anion. The most electronegative Cl halide minimizes thermal atomic fluctuations, favoring optoelectronic performance. CsPbI<sub>3</sub> is improved by Cl-doping. Nonadiabatic molecular dynamics simulations demonstrate that charge carrier lifetime is extended by nearly an order of magnitude when atomic fluctuations are minimized, due to reduced electron-vibrational interactions, in agreement with experiments. The detailed atomistic examination of the significant impact of correlated motion of the A-site and BX<sub>3</sub> sublattices and its influence on perovskite stability and exciton lifetime offers theoretical guidelines for optimizing perovskite optoelectronic devices.