Core-shell cadmium sulphide @ silver sulphide nanowires surface architecture: Design towards photoelectrochemical solar cells.

Design and development of cadmium sulphide core with silver sulphide shell assembly in nanowire (NWs) surface architecture has been explored through room temperature, simple chemical route towards photoelectrochemical solar cell application. Incorporation of low band gap AgS nanoparticles over the outer surface of the chemical bath deposited CdS NWs has been achieved by simple cation exchange route based on negative free energy of formation. Shell optimization has been performed by investigating structure, surface morphologies and optical analyses and correlated with the photovoltaic parameters. Interestingly, core-shell CdS NWs/ AgS exhibits 1.5 better performance in terms of linear voltammetry, photocurrent transient response and the photo stability than bare CdS. Furthermore, three-fold enhancement in photoelectrochemical conversion efficiency have been observed for optimized FTO/ CdS NWs/AgS compared to bare FTO/CdS NWs due to the augmented light harvesting and condensed charge recombination. External quantum efficiency exhibits 24% for the optimized CdS NWs/ AgS core shell structure. Mott-Schottky and electrochemical impedance spectroscopy measurements have been used for better understanding the impact of gradual growth of AgS over CdS NWs which directly influences the overall photocurrent density of the devices.