Enhanced P-type conductivity in Sb2Se3 through alkali and alkaline earth metal doping

Abstract

Antimony selenide (Sb₂Se₃) has recently received much attention as a potential candidate for light absorbers in thin-film photovoltaic technologies because of its earth abundance, nontoxicity, and promising electrical and optical properties. Treatments with alkali and alkaline earth elements have been shown to enhance the performance of conventional thin-film solar cells. In this study, we employ hybrid density functional theory to investigate the electronic structures and defect properties of Sb₂Se₃ doped with alkali and alkaline earth elements in comparison to those of native undoped Sb₂Se₃. Our results indicate that undoped Sb₂Se₃ exhibits slight p-type conductivity and semi-insulating property under Se-rich and Se-poor conditions, respectively, consistent with experimental observations. The calculations further reveal that potassium, magnesium, and calcium act as acceptor dopants in a Se-rich environment, improving the p-type conductivity by preferentially forming antisite defects, whereas sodium has a negligible impact. Notably, calcium substitution at Sb site shows the lowest formation energy and a shallow transition energy level, significantly enhancing p-type conductivity. Given its earth abundance, eco-friendliness, and nontoxicity, thus, calcium presents a promising p-type dopant for improving the conductivity and efficiency of Sb₂Se₃-based devices.