Lattice disorder influences the photocarrier dynamics in lead halide perovskites

Abstract

Revealing the structural impact of lead halide perovskites on photocarrier dynamics is essential for the associated solar cells but deficient in experimental visualization. In this study, with femtosecond spectroscopy, we for the first time explored the contribution of the disorder of the distorted PbX₆ octahedrons and A-site cations on the carrier behaviours. It was found that photoinduced carriers recombine almost twice slower and diffuse 20% faster in the disordered, β-phased samples than in the ordered, γ-phased ones. Yet within the same phase, with a similar PbX₆ orientation but various A-site mobility, the carrier diffusion and recombination have no apparent difference. Thus we firmly conclude that lattice disorder effectively influences the carrier dynamics and therein the Pb–X sublattice is worth more than A-site cations, which should inspire future lead halide perovskite design and applications.