Solar Cells of Antimony Sulfide-Selenide Absorber Thin Films with ZnS-CdS Window Layers

Antimony chalcogenides, Sb₂S₃ and Sb₂Se₃, and their solid solutions Sb₂S_xSe_3-x with band gaps in the 1.88 – 1.1 eV interval are prospective absorber materials for thin film solar cells. In the present work, we used thermal evaporation of commercial Sb₂S₃ and Sb₂Se₃ compounds to obtain the thin films of Sb₂S_xSe_3-x with optical band gaps of 1.29 – 1.6 eV, depending on the value of x, and optical absorption coefficients of > 10⁵ cm^-1 in the visible region. The films show photoconductivity of 10^-6 - 10^-5 Ω^-1 cm^-1. Heterojunction solar cells of these thin films as absorbers were developed with CdS, ZnO, or ZnS/CdS bilayer as buffer/window on SnO₂:F-coated glass substrates. With colloidal graphite paste of 0.2 – 1 cm² area as the back contacts, the solar cell of glass/FTO/ZnS-CdS/Sb₂SxSe_3-x/C-Ag structure showed an open circuit voltage of 0.435 V, a short circuit current density of 32.9 mA cm^-2, and a conversion efficiency of 7.34 % with Fill Factor, 0.52. We present the details of preparation of the different component films, their properties, and the latest results on the performance of these solar cells.