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

摘要

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 [Phys. Rev. Lett. 108, 068701 (2012) is used as a metric for the screening. After constructing the current-voltage curve, the SLME 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_2Ⅱ-GeSe_4 with Ⅱ = Cd and Hg, and Cu_2-Ⅱ-SnS_4 with Ⅱ = Cd, Hg, and Zn have a higher theoretical efficiency compared with the materials currently used as absorber layer.