Systematic Variation of Material Characteristics with Chemical Composition in Antimony Sulfide Selenide Thin Films and Its Relevance to Solar Cell Performance

Antimony sulfide (Sb 2 S 3 ) and antimony selenide (Sb 2 Se 3 ), with optical bandgaps ( E g ) of 1.88 and 1.1 eV, respectively, both crystallize in the orthorhombic structure and can produce Sb 2 S x Se 3– x of intermediate E g for solar cells. Herein, powder sources of Sb 2 S 3 and Sb 2 Se 3 in different mass ratios in vacuum thermal evaporation are used to produce Sb 2 S x Se 3– x thin films of thickness 455 nm. These films show a systematic variation in their characteristics with x —A, Sb 2 S 2.05 Se 0.95 ( E g , 1.51 eV); B, Sb 2 S 1.71 Se 1.29 (1.44 eV); C, Sb 2 S 1.24 Se 1.76 (1.40 eV); D, Sb 2 S 0.64 Se 2.36 (1.32 eV); and E, Sb 2 S 0.44 Se 2.56 (1.29 eV)—in the light‐generated current density, and in their photoconductivity. Solar cells of SnO 2 :F/CdS(100 nm)/Sb 2 S x Se 3– x (455 nm)/C‐Ag with Sb 2 S x Se 3– x films of compositions A – E show open circuit voltages ( V oc ) of 0.566–0.418 V; short circuit current densities of 9.65–31.5 mA cm −2 ; fill factors of 0.38–0.52; and conversion efficiencies ( η ) of 2.1–6.8%. Seven series‐connected solar cells of E 7 cm 2 in area produce 34.2 mW with V oc of 2.83 V and η 4.88%. In view of their operational stability and the material perspectives of Sb 2 S x Se 3– x , considerations considerations to improve these solar cells are discussed.