Enhanced Performance of Quantum Dots Sensitized Solar Cell Utilizing Copper Indium Sulfide and Reduced-Graphene Oxide with the Presence of Silver Sulfide

In this study, rGO/CuInS2 has been successfully prepared onto TiO2 thin film using solvothermal method followed by Ag2S deposition layer by successive ionic layer adsorption and reaction deposition (SILAR) technique. The morphology, structural, and optical properties of TiO2/rGO/CuInS2 thin film were investigated by using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and ultra-violet-visible near infrared spectrophotometer (UV-Vis). For electrical properties, electrochemical impedance spectra (EIS) and current-voltage (I-V) test investigated the interfacial charge-transfer resistances and the conversion efficiency of the samples. Results showed that the average particles size of the samples ranged from ±46.52 to ±53.97 nm in diameter. UV-VIS analysis indicated that TiO2/rGO/CuInS2 thin film showed better light absorption capability with the presence of Ag2S deposition layers. The rGO/CuInS2 quantum dot sensitized with Ag2S layers exhibit a photovoltaic power conversion efficiency of 0.33%, which has great improvement of short circuit current (ISC) comparing with that of rGO/CuInS2 quantum dot sensitized without Ag2S deposition layers.