Ternary CuInS2 photoelectrodes created using the sulfurization of Cu–In metal precursors for photoelectrochemical applications

Abstract Copper indium disulfide semiconductor layers are deposited onto glass substrates or fluorine-doped tin oxide-coated glass substrates with the reactive sulfurization and the sputtering of Cu–In metal precursors. X-ray diffraction patterns and energy dispersive analysis of X-ray results reveal that the samples change from the Cu-rich tetragonal CuInS 2 to the In-rich CuInS 2 phase with an increase in the [In]/[In + Cu] molar ratio in the metal precursors. The thicknesses and direct band gaps of the samples, determined from surface profile measurements and transmittance and reflectance spectra, are in the ranges of 0.82–1.29 μm and 1.39–1.53 eV, respectively. The carrier density and mobility of samples are in the ranges of 3.29 × 10 14 –1.9 × 10 20 cm −3 and 0.58–17.41 cm 2 /V s, respectively. A sample with an [In]/[In + Cu] molar ratio of 0.53 has a maximum photo enhancement current density of 5.81 mA/cm 2 at an applied bias of 0.4 V vs. an Ag/AgCl electrode in aqueous Na 2 S (0.35 M) + K 2 SO 3 (0.25 M) solution.