Analysis of ultrafast carrier dynamics and steady-state reflectivity on lattice expansion in metal halide perovskite during continuous illumination

Abstract

Lattice expansion in hybrid halide perovskite directly affects its photoelectric properties and the stability of perovskite-based optoelectronic devices, which was certified also to closely connect with relevant inducing mechanisms. From the perspective of carrier relaxation dynamics and dielectric properties, we report the results employing ultrafast time-resolved transient and steady-state reflectivity technology to diagnose the lattice expansion occurring in bulk hybrid perovskite MAPbI3 during continuous illumination and directly heating, respectively. Upon continuous illumination at a constant temperature, there were no evident structural changes in MAPbI3, but in the condition of naturally temperature changes, the lattice expansion can be induced by continuous light illumination and is consistent with the effect of heat-inducted expansion. The present results are based on the physical mechanism that the change of the electronic structure caused by lattice expansion leads to the change of the dielectric properties in MAPbI3 and sequentially to the change of light reflectivity.