Defect-Assisted Recombination in Semiconductors and Photovoltaic Device Parameters from First Principles

TL;DR

This paper presents a first-principles method to accurately calculate defect-assisted recombination rates in semiconductors, improving understanding of defect impacts on photovoltaic efficiency and guiding the discovery of defect-tolerant materials.

Contribution

It introduces a comprehensive first-principles approach to evaluate defect-assisted recombination and photovoltaic parameters, surpassing common approximations and aiding material discovery.

Findings

Demonstrates the method on seven photovoltaic semiconductors

Highlights limitations of traditional recombination models

Provides insights into defect tolerance in photovoltaics

Abstract

We introduce a method to calculate defect-assisted Shockley-Read-Hall (SRH) recombination rates in imperfect semiconductors from first principles. The method accounts for the steady state recombination dynamics under given non-equilibrium conditions (split quasi Fermi levels), by invoking a full solution to the rate equations describing transitions across the band gap via all possible charge states of the defect. Transition rates due to radiative and non-radiative multi-phonon emission processes are calculated from first principles. The method is used to evaluate the effect of selected defects on the photovoltaic device parameters of seven emergent photovoltaic semiconductors. These examples clearly highlight the limitations of commonly employed approximations to the recombination dynamics. Our work advances the description and understanding of defect-induced losses in photovoltaics and provides a basis for developing the important concept of defect tolerant semiconductors and to discover high-performance photovoltaic materials computationally.