First-principles study of the optoelectronic properties and photovoltaic absorber layer efficiency of Cu-based chalcogenides

TL;DR

This study uses first-principles calculations to evaluate the optoelectronic properties of Cu-based chalcogenides, identifying promising materials with higher theoretical photovoltaic efficiency than current absorbers.

Contribution

It introduces a computational screening approach using SLME to identify new Cu-based chalcogenides with superior photovoltaic potential.

Findings

Cu$_2$-II-GeSe$_4$ with II=Cd, Hg shows high efficiency

Cu$_2$-II-SnS$_4$ with II=Cd, Zn also exhibits high efficiency

Band gap nature and absorptivity significantly influence maximum efficiency

Abstract

Cu-based chalcogenides are promising materials for thin-film solar cells with more than 20% measured cell efficiency. Using first-principles calculations based on density functional theory, the optoelectronic properties of a group of Cu-based chalcogenides Cu$_2$-II-IV-VI$_4$ is studied. They are then screened with the aim of identifying potential absorber materials for photovoltaic applications. The spectroscopic limited maximum efficiency (SLME) introduced by Yu and Zunger is used as a metric for the screening. After constructing the current-voltage curve, the maximum spectroscopy dependent power conversion efficiency is calculated from the maximum power output. The role of the nature of the band gap, direct or indirect, and also of the absorptivity of the studied materials on the maximum theoretical power conversion efficiency is studied. Our results show that Cu$_2$-II-GeSe$_4$ with II=Cd and Hg, and Cu$_2$-II-SnS$_4$ with II=Cd and Zn have a higher theoretical efficiency compared to the materials currently used as absorber layer.