Chemical Synthesis of Nanocrystalline Silver Sulphide Thin Films for Solar Cell Applications

Semiconduncting silver sulphide thin films have been deposited by chemical bath deposition (CBD) method onto the glass and fluorine doped tin oxide (FTO) coated glass substrate from an aqueous alkaline bath at room temperature (300K). The deposition bath consists of silver nitrate, thiourea and ammonia. The preparative parameters such as ion concentration, deposition time, pH of solution, were optimized for Ag₂S thin films. The as deposited films on glass substrate were studied for their structural, surface morphological, optical and electrical properties using techniques such as X-ray diffraction, atomic force microscopy (AFM), Scanning electron microscopy (SEM), optical absorption and dc two probe method. The photoelectrochemical (PEC) investigations of Ag₂S films were carried out by using chemical cell configuration n-Ag₂S/1M/NaOH-Na₂S-S/Pt. and the nanocrystalline films were found to be photoactive in polysulphide solution. The dynamic current-voltage (I-V) characteristic was examined at room temperature. It is concluded that the films exhibit n-type electrical conductivity. The photovoltaic output characteristics were used to calculate the fill factor (FF) and power conversion efficiency (η). The low conversion efficiency 0.038%, may be due high series resistance R_s and low shunt resistance R_sh of the cell and interface states, which are responsible for the recombination mechanism.