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

Abstract

Antimony sulfide (Sb2S3) and antimony selenide (Sb2Se3), with optical bandgaps (Eg) of 1.88 and 1.1 eV, respectively, both crystallize in the orthorhombic structure and can produce Sb2SxSe3–x of intermediate Eg for solar cells. Herein, powder sources of Sb2S3 and Sb2Se3 in different mass ratios in vacuum thermal evaporation are used to produce Sb2SxSe3–x thin films of thickness 455 nm. These films show a systematic variation in their characteristics with x—A, Sb2S2.05Se0.95 (Eg, 1.51 eV); B, Sb2S1.71Se1.29 (1.44 eV); C, Sb2S1.24Se1.76 (1.40 eV); D, Sb2S0.64Se2.36 (1.32 eV); and E, Sb2S0.44Se2.56 (1.29 eV)—in the light‐generated current density, and in their photoconductivity. Solar cells of SnO2:F/CdS(100 nm)/Sb2SxSe3–x(455 nm)/C‐Ag with Sb2SxSe3–x films of compositions A–E show open circuit voltages (Voc) 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 cm2 in area produce 34.2 mW with Voc of 2.83 V and η 4.88%. In view of their operational stability and the material perspectives of Sb2SxSe3–x, considerations considerations to improve these solar cells are discussed.