CuSb: The dominant defect in Cu-rich CuSbS2 solar cells fabricated by sulfurizing co-sputtered Cu–Sb precursor.

Understanding the elemental composition and point defect properties is crucial for improving device performance in Chalcogenide thin film solar cells. The correlation between composition and defect characteristics of CuSbS 2 thin film sulfurized from metallic precursors was systematically investigated. Interestingly, it was found that CuSbS 2 polycrystalline thin film maintains an overall Cu-rich composition with a Cu/Sb ratio greater than 1, regardless of the initial precursor compositions. Besides, no obvious difference in the performance of integrated devices is observed, due to the similar Cu/Sb atomic ratios and electronic properties (carrier concentration and mobility) in these CuSbS 2 thin films. By conducting admittance spectroscopy analysis on CuSbS 2 devices, identical defect energy was obtained at 280 meV above the valence band maximum, which can be ascribed to Cu Sb. This could be mainly explained by the Cu-rich composition induced low formation energy of Cu Sb. Therefore, further defects engineering focusing on Cu Sb is required to boost the device efficiency of CuSbS 2 solar cells. • The correlation between composition and defect characteristics has been systematically studied in CuSbS 2 solar cells. • Polycrystalline CuSbS 2 thin-films exhibit a Cu-rich composition across a wide range of initial precursor compositions. • Polycrystalline CuSbS 2 shows consistent Cu/Sb ratios and electronic properties, regardless of precursor compositions. • Cu Sb is revealed to be the dominant defect in Cu-rich CuSbS 2 thin-film prepared by the co-sputtering method. [ABSTRACT FROM AUTHOR]