Role of Solution Chemistry in Determining the Morphology and Photoconductivity of Electrodeposited Cuprous Oxide Films

Electrodeposition of single-phase, crystalline Cu2O thin films is demonstrated using acidic lactate/Cu2+ solutions. Relative speciation distributions of the various metal complex ions present under different growth conditions are calculated using reported equilibrium association constants and supported experimentally by UV–vis absorption spectroscopy. Cu2O films grown from acidic lactate solutions can exhibit a distinctive flowerlike, dendritic morphology in contrast to the faceted, dense films obtained using alkaline lactate solutions. Dependence of thin film morphology on the lactate/Cu2+ molar ratio and the applied potential is described. Hot point probe measurements have been used to determine the p-type conductivity of these Cu2O films. A short circuit current density of 23 μA/cm2 under 0.583 mW/cm2 monochromatic green light emitting diode (LED) illumination was measured for a Cu2O film grown at pH = 5.27, which was substantially larger than that of a Cu2O film deposited under basic conditions.