Fabricating over 7%-efficient Sb₂(S,Se)₃ thin-film solar cells by vapor transport deposition using Sb₂Se₃ and Sb₂S₃ mixed powders as the evaporation source

In this study, Sb₂(S,Se)₃ thin films are fabricated using the vapor transport deposition (VTD) method, with Sb₂Se₃ and Sb₂S₃ mixed powders as the evaporation source. The performance of the corresponding glass/ITO/CdS/Sb₂(S,Se)₃/Au solar cells are found to be correlated to the mass ratio between Sb₂S₃ and the overall powder mixture. The properties of the Sb₂(S,Se)₃ thin films and cell devices adopting four different Sb₂S₃ mass ratios (x = 0.1, 0.25, 0.5 and 0.75) are compared. Further, the electrical properties – from dark and light J-V measurements; structural properties – from X-ray diffraction and scanning electron microscope measurements; and carrier-recombination rates at the buffer/absorber interface in the space-charge region (SCR) and in the quasi-neutral region – from temperature-illumination-dependent open-circuit voltage (V_OC) measurements – are compared. It is found that a Sb₂(S,Se)₃ solar cell with a Sb₂S₃ mass ratio of 0.25 had optimal crystallinity, the lowest density of deep traps and the smallest carrier-recombination rates at the interface, leading to a high efficiency of 7.31%.