(615c) Solution Speciation Effects On Electrodeposited Cuprous Oxide Films for Solution-Processed Photovoltaics

Panzer, M. J., Tufts University

Electrodeposited cuprous oxide (Cu2O) is a p-type semiconductor that holds promise for constructing future photovoltaic devices using solution-based processes that require low energy input, feature benign chemistry, and contain earth abundant materials. Recently, we have successfully demonstrated the electrodeposition of single-phase, polycrystalline Cu2O thin films from acidic lactate/Cu2+ solutions. A distinctive dendritic, flowerlike Cu2O morphology is observed when films are grown from acidic lactate-based deposition baths; this stands in stark contrast to the faceted, dense films obtained from traditionally used alkaline solutions. Numerical simulation and UV-Vis absorption spectroscopy have been employed to demonstrate key differences in the relative distributions of various metal complex ions present under different growth conditions. Hot point probe measurements confirm the p-type conductivity of all Cu2O films obtained in this work. Importantly, a short circuit current density of 23 uA/cm2 under monochromatic green LED illumination (0.583 mW/cm2) was measured for a Cu2O film grown at pH 5.3, which was substantially larger than that of a Cu2O film deposited from basic lactate solution. These findings suggest that gaining a deeper understanding of the effects of metal complex ion speciation on the ultimate optoelectronic properties of electrodeposited Cu2O films can lead to improved performance for realizing efficient photovoltaic devices with this material.