The influence of polarity of electrodeposited Cu2O thin films on the photoelectrochemical performance

Both polar and non-polar Cu2O thin films were electrodeposited in electrolytes of different pH, and their photoelectrochemical activities in water were analyzed. The surface morphology of these tailored-polarity Cu2O films was analyzed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD), and their photoactivity was characterized through photoluminescence and Mott-Schottky measurement of the defect structure, diffusion length, carrier concentration, and charge separation. Through this, the tetrahedral surface morphology of a polar Cu2O thin film was found to exhibit a higher photocurrent in the visible spectrum than the pyramidal surface morphology of a non-polar Cu2O film. Furthermore, the higher flat-band potential and carrier concentration identified in the polar Cu2O by Mott-Schottky analysis was found to result in a higher charge separation. (C) 2014 The Japan Society of Applied Physics