Static and dynamic disorder in triple-cation hybrid perovskites

A detailed understanding of the carrier dynamics and emission characteristics of organic-inorganic lead halide perovskites is critical for their optoelectronic and energy harvesting applications. In this work, we reveal the effect of the crystal lattice disorder on the photogenerated electron-hole pairs through low-temperature photoluminescence (PL) measurements. We provide strong evidence that the intrinsic disorder forms a sub-bandgap tail density of states, which determines the emission properties at low temperatures. The PL spectra indicate that the disorder evolves with increasing temperature, changing its character from static to dynamic. This change is accompanied by a rapid drop in the PL efficiency, originating from the increased mobility of excitons/polarons, which enables them to reach deep nonradiative recombination centers more easily.