Hot carrier cooling dynamics in low-dimensional lead halide perovskites

Abstract

Hot carrier cooling in halide perovskites is governed by the interplay of carrier-carrier and carrier-phonon interactions, and so the study of their dynamics can reveal important underlying photophysical processes operating in these materials. Here, ultrafast pump-push-probe spectroscopy is used to isolate hot carrier dynamics in lead halide perovskite nanomaterials spanning a range of sizes and shapes. A weak size-dependence is shown by cuboidal CsPbBr3 nanocrystals, while 2D CsPbBr3 nanoplatelets and Ruddlesden-Popper (PEA)2PbI4 display a hot phonon bottleneck that becomes increasingly suppressed with greater excitonic character. This is attributed to an enhanced influence of carrier-carrier scattering in low-dimensional perovskites.