Accurate calculation of excitonic signatures in the absorption spectrum of BiSBr using semiconductor Bloch equations

TL;DR

This paper introduces a computationally efficient method based on semiconductor Bloch equations for accurately predicting excitonic effects in the optical absorption spectrum of BiSBr, aligning well with experimental and ab initio results.

Contribution

The paper develops and validates a semiconductor Bloch equation-based approach for optical property calculations, offering a less computationally intensive alternative to ab initio methods.

Findings

Excellent agreement with experimental optical gap

Close match with Bethe-Salpeter calculations

Suitable for large or low-dimensional systems

Abstract

In order to realize the significant potential of optical materials such as metal halides, computational techniques which give accurate optical properties are needed, which can work hand-in-hand with experiments to generate high efficiency devices. In this work a computationally efficient technique based on semiconductor Bloch equations (SBEs) is developed and applied to the material BiSBr. This approach gives excellent agreement with the experimental optical gap, and also agrees closely with the excitonic stabilisation energy and the absorption spectrum computed using the far more computationally demanding \textit{ab initio} Bethe-Salpeter approach. The SBE method is a good candidate for theoretical spectroscopy on large- or low dimensional systems which are too computationally expensive for an \textit{ab initio} treatment.