Atomistic Origin of Transparent Absorption Spectra of Halide Perovskites

Differential spectroscopy has emerged as a valuable characterisation tool in materials science. Transient absorption spectroscopy (TAS) involves probing changes in optical absorption following laser excitation. While TAS spectra provide information about carrier recombination kinetics, interpreting individual features remains challenging. In this talk, we present a novel procedure to calculate TAS spectra for crystals using first-principles density functional theory calculations. Our approach simulates changes in band-to-band transitions within the electronic band structure, encompassing ground-state bleaching and photo-induced absorption processes.<br/><br/>This methodology is particularly relevant to the investigation of halide perovskite materials, where TAS can provide insights into their unique optical properties and charge carrier dynamics. Applications will be given to a range of inorganic and hybrid perovskite compositions. Our procedures are implemented in the PyTASER code, an open-source package that facilitates the implementation of our simulation approach to help accelerate materials characterisation and bridge the gap between modelling and measurements for researchers working on halide perovskites.