Photoelectrochemical performance of Cu-Zn-In-S film grown using one-step electrodeposition

Copper-zinc-indium-sulfide (Cu-Zn-In-S) semiconductor films are deposited onto fluorine-doped-tin-oxide-coated glass substrates using one-step electrodeposition. The effect of the [Zn]/[Cu + Zn] molar ratio in the solution bath on the structural, optical, and electrical properties of samples is investigated. X-ray diffraction patterns reveal that the samples are the quaternary Cu-In-Zn-S phase with a small amount of ZnS impurity. The thicknesses and direct band gaps of the samples, determined from surface profile measurements and transmittance and reflectance spectra, are in the ranges of 0.68-2.09 μm and 1.43-3.03 eV, respectively. The flat-band potentials of the samples obtained from Mott-Schottky measurements are the range of -1.03 to -1.44 V vs. an Ag/AgCl reference electrode. All samples are n-type semiconductors with a carrier density of 8.4 × 10¹⁵ to 2.0 × 10 ¹⁴ cm^-3 and a mobility of 96-263 cm² V ^-1 s^-1. The samples with the Cu:Zn:In:S molar ratio of 1:1.08:2.16:5.20 had a maximum photo-enhanced current density of 1.50 mA cm ^-2 at an applied bias of -0.25 V vs. an Ag/AgCl electrode in contact with an electrolyte containing Na₂S and K₂SO₃ under illumination. The results show that Cu-Zn-In-S films can be obtained using one-step electrodeposition for photoelectrochemical applications.