In this report, emplectite (CuBiS₂) semiconductor has been deposited on mesoporous TiO₂ using gas–solid reaction method. For the first time, CuCl₂ and BiCl₃ are solution-coated on mesoporous TiO₂ films, and thereafter reacted with H₂S gas in an H₂S atmosphere. The CuBiS₂ film is further confirmed using X-ray diffraction; thus, demonstrating the pure phase of CuBiS₂. CuBiS₂ film shows high spectral absorption with an energy gap (E_g) of 2.18 eV. Furthermore, devices have a structure consisting of FTO/compact-TiO₂/mesoporous-TiO₂/CuBiS₂/P3HT/Ag have been fabricated and hence exhibit high photoresponse performance.