Preparation of chemical bath synthesized ternary Ag–Sn–S thin films as the photoelectrodes in photoelectrochemical cell

Abstract

In this study, ternary Ag–Sn–S thin films are grown on glass and indium–tin-oxide coated glass substrates using chemical bath deposition. The structural, optical, electrical, and photoelectrochemical properties of the Ag–Sn–S thin films on substrates are investigated as a function of the [Ag]/[Ag + Sn] molar ratio in the precursor solution. X-ray diffraction patterns show that the samples change from Ag2S/Ag8SnS6, Ag8SnS6, Ag8SnS6/Ag4Sn3S8, and Ag8SnS6/Ag2S/SnS mixing phases with a decrease in the [Ag]/[Ag + Sn] molar ratio in the precursor solution. With a decrease in the [Ag]/[Ag + Sn] molar ratio in the precursor solution, the (0 2 2) diffraction peak of samples shifts to lower angles. A pure orthorhombic Ag8SnS6 phase is obtained in the samples prepared with [Ag]/[Ag + Sn] molar ratios in the precursor solution of 0.5–0.6. The energy band gaps of the samples obtained from transmittance and reflectance spectra are in the range of 1.17–1.48 eV. The carrier concentrations and mobilities of the samples are in the ranges of 2.5 × 1012–3 × 1014 cm−3 and 14.02–23.05 cm2/V s, respectively. The maximum photoelectrochemical performance of the samples in aqueous solution containing SO32− and S2− ions is 1.13 mA/cm2 at an external potential of 0 V vs. an Ag/AgCl reference electrode under 100 mW/cm2 light illumination from a Xe lamp source.