Effect of Cu content in CuSbS2 thin films using hybrid inks: Their photovoltaic properties and defect characteristics

Abstract

CuSbS2 (CAS) thin films were grown with different Cu/Sb precursor ratios using a non-vacuum-based hybrid ink method. The prepared precursor inks were coated on Mo-coated soda lime glass and a subsequent sulfurization process was carried out. X-ray diffraction (XRD) patterns confirmed the presence of the CuSbS2 phase for an optimal Cu/Sb precursor ratio; for other ratios, additional secondary phases were also observed. Then, CuSbS2 solar cells were fabricated to compare the photovoltaic performances. The sample with the pure CuSbS2 phase showed better photovoltaic properties than those films containing secondary phases. The best CuSbS2 solar cell with optimum Cu/Sb ratio exhibited the conversion efficiency of 2.75%. The temperature-dependent light and dark current density–voltage (JV-T) characteristics were measured to investigate the recombination process, and R–J curves were extracted to study the photovoltaic characteristics, including parasitic resistances. The depletion width and carrier concentrations were also compared from capacitance–voltage (C-V) measurements of the solar cells prepared with the films of various Cu/Sb ratios. Using admittance spectroscopy (AS), the dominant defect energy level was deduced and determined as 0.23 eV above the valence band maximum. Drive-level capacitance profiling (DLCP) was applied to characterize the defect behavior of the device with optimum Cu content.