Insights to Carrier-Phonon Interactions in Lead Halide Perovskites via Multi-Pulse Manipulation

A fundamental understanding of the hot-carrier dynamics in halide perovskites is crucial for unlocking their prospects for next generation photovoltaics. Presently, a coherent picture of the hot carrier cooling process remains patchy due to temporally overlapping contributions from many-body interactions, multi-bands, band gap renormalization, Burstein-Moss shift etc. Pump-push-probe (PPP) spectroscopy recently emerges as a powerful tool complementing the ubiquitous pump-probe (PP) spectroscopy in the study of hot-carrier dynamics. However, limited information from PPP on the initial excitation density and carrier temperature curtails its full potential. Herein, this work bridges this gap in PPP with a unified model that retrieves these essential hot carrier metrics like initial carrier density and carrier temperature under the push conditions, thus permitting direct comparison with traditional PP spectroscopy. These results are well-fitted by the phonon bottleneck model, from which the longitudinal optical phonon scattering time tau(LO), for MAPbBr(3) and MAPbI(3) halide perovskite thin film samples are determined to be 240 +/- 10 and 370 +/- 10 fs, respectively.

Automated summary

A thorough understanding of hot-carrier dynamics in halide perovskites is crucial for advancing next generation photovoltaics. Pump-push-probe (PPP) spectroscopy has recently emerged as a powerful tool for studying hot-carrier dynamics, but limited information on initial excitation density and carrier temperature has hindered its full potential. This work presents a unified model that allows the retrieval of these essential hot carrier metrics under the push conditions, enabling direct comparison with traditional pump-probe spectroscopy.