Characterization of defects in copper antimony disulfide

Abstract

Copper antimony disulfide (CuSbS₂) with the chalcostibite structure is a promising photovoltaic (PV) absorber material with several excellent measured optoelectronic properties, such as a solar matched band gap and tunable hole concentration. However, much less is known from an experimental perspective about defects in CuSbS₂, even though the defects are critical for solar cell performance. Here, we explore the defect properties in CuSbS₂ thin film materials and photovoltaic devices using photoluminescence and capacitance-based spectroscopies, as well as first principles theoretical calculations. We measured three electrically and optically active acceptor defects in CuSbS₂, and assigned them to the copper vacancies, sulfur vacancies, and/or copper on antimony antisites by comparison with theoretical calculations. Their activation energies, concentrations, and capture cross sections have been determined and compared to other chalcogenide absorber materials. These fundamental parameters should enable more accurate simulations of CuSbS₂ PV devices, paving the way for future improvements in CuSbS₂ solar cell efficiencies.