Ternary Ag-In-S thin films deposited using aqueous solutions for photoelectrochemical hydrogen production

  • Mr Ching-Chen Wu, Department of Chemical Engineering, National Chung Cheng University, Taiwan
  • Dr Wen-Sheng Chang, Energy and Environmental Laboratories, Industrial Technology Research Institute, Taiwan
  • Dr Kong-Wei Cheng, Department of Chemical and Materials Engineering, Chang Gung University, Taiwan
  • Dr Chao-Ming Huang, Department of Environmental Engineering, Kun San University, Taiwan
  • Tai-Chou Lee, Department of Chemical Engineering, National Chung Cheng University, Taiwan

    • I-III-VI compounds are direct energy-gap semiconductors, and have been utilized in light emitting diodes, nonlinear optics, and photovoltaic solar cells. These ternary I-III-VI based semiconductors, especially AgInS2, are also expected to make a good solar cell absorber layers (e.g. CdS/AgInS2/CuInSe2). In this study, a deposition technology based on the ultrasonic chemical bath deposition (UCBD) was developed. The Ag-In-S thin films were prepared by changing the silver to indium molar ratios ([Ag]/[In]) from 1 to 5 in the precursor solutions, while the [S] / [Ag] was kept constant. The films were annealed in vacuum at 400 °C for 1h. The crystalline phases of the samples were identified by grazing incidence X-ray diffraction (GIXRD). The sample prepared from the [Ag]/[In] = 1 precursor solution (sample A) shows a major cubic- AgIn5S8 phase, the sample from [Ag]/[In] = 5 (sample B) shows a major orthorhombic-AgInS2 phase, and the sample C ([Ag]/[In] = 4) shows AgInS2/AgIn5S8 mixtures. The photocurrent densities of samples A, B, and C were 0.05, 2.5, and 3.8 mA/cm2, respectively, with a bias of 0.5 V vs. SCE reference electrode. The experiments were conducted in a 0.25 M K2SO3 and 0.35 M Na2S aqueous electrolyte under radiation of 300 W Xe light (100 mW/cm2). The rates of H2 evolution of samples A, B, and C were 8.2, 408.2, and 612.2 micromol/cm2.h, respectively.