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Single step synthesis of monophase CuSbS2 thin films by electro-deposition in ionic liquid electrolyte based on choline chloride and urea (ChCl:U) eutectic mixture is described. The formation of binary CuxS and SbxSy film phases using CuCl2 and SbCl3 precursors along with Na2S2O3 as sulfur source in ChCl:U are established as -0.59 V and -0.36 V vs. Pt, respectively by cyclic voltammetry and used to optimize CuSbS2 thin films growth potential and precursor composition. CuSbS2 films deposited at -0.65 V vs Pt with 1:1 Cu to Sb precursor ratio at 80⁰C are highly crystalline in chalcostibite orthorhombic structure. Deviant Cu/Sb ratio at 1:0.71 and 1:1.4 reveal inclusion of Cu3SbS3 and Sb2S3, respectively. Direct 1.65 eV band gap for single phase CuSbS2 film and with inclusive secondary phases at 1.73±0.1 eV and 2.13 eV is observed. As-deposited CuSbS2 films are p-type and n-p hetero-junction device in the n-ZnO/p-CuSbS2/Ag structure shows rectifying I-V curves and dependence on the CuSbS2 film growth conditions.