Hot Phonon and Auger Heating Mediated Slow Intraband Carrier Relaxation in Mixed Halide Perovskite

Abstract

A clear understanding of excited carrier relaxation to their equilibrium state via carrier-phonon, carrier-carrier interaction etc. is always required for the advancement of perovskite based device performance. Organic/inorganic lead halide perovskite have shown remarkable slow hot carrier cooling properties. Herein, we investigate the effect of hot phonon and Auger heating on hot carrier relaxation dynamics in Methyl-ammonium lead iodide-chloride (CH3NH3PbI3-XClX or mixed halide) perovskite using transient absorption spectroscopy. The reduced energy-loss rate on sub-picosecond time scale clearly shows the non-equilibrium build-up of longitudinal optical and acoustic phonon modes (carrier-phonon interaction) at low pump excitation (1018 cm-3). However at high pump excitation (1019 cm-3), dominating Auger heating process (carrier-carrier interaction) further reduces the energy-loss rate by more than two order of magnitude and delays the carrier relaxation process to tens of picoseconds which makes perovskite as a promising candidates in hot carrier photovoltaic.