Influence of dipping cycle on structural, optical and photoelectrochemical characteristics of single phase polycrystalline AgInS2 thin films on ITO prepared by aqueous chemical reaction

Thin films of polycrystalline AgInS2 were deposited on indium-tin oxide glass substrates by chemical bath deposition process. Various dipping cycles (1, 2, 3, 4 and 5) were taken into consideration. The influence of dipping cycle on structural, optical, electrical and photoelectrochemical characteristics of the AgInS2 thin films were investigated. The X-ray diffraction patterns indicated that all the samples revealed single phase of orthorhombic AgInS2 with polycrystalline structure. The thickness of samples in a range of 0.82-2.67 μm analyzed by α-step instrument. The optical band gap of all AgInS2 films were 1.94 eV calculated by transmittance spectra, respectively. All the samples revealed n-type semiconductor behaviors by Hall measurement. The carrier concentrations, mobility and resistivity of the AgInS2 films at room temperature were in the range of 1012-1015 cm−3, 1.9-15 cm2 V−1 s−1 and 103-105 Ω cm, respectively. We found that the dipping 3 cycles AgInS2 film had a better photoelectrochemical performance with photocurrent density of 3.50 mA/cm2 bias 0.5 V vs. SCE reference electrode under a 300 W Xe lamp illumination with the intensity of 100 mW/cm2. This value was about 3 times higher than the dipping 5 cycles AgInS2 film. Observed higher photocurrent density was likely due to a suitable thickness, higher carrier mobility and lower charge transfer resistance.