Electrodeposited p-type Cu2O thin films at high pH for all-oxide solar cells with improved performance

We report the electrodeposition of cuprous oxide (Cu2O) films from cupric sulfate-lactate electrolytes at high pH 13.5 and their performance in all-oxide fluorine-doped tin oxide/Cu2O/aluminium-doped zinc oxide solar cells. The deposit grains are found to grow with rather randomly distributed < 111 > and < 100 > crystal orientations and have a poorly-definded morphology with evidence of chemical dissolution that takes place during the deposition process. Significant improvements in the solar cell performance with high power conversion efficiencies of up to 1.55% is achieved, which is much better that those ( < 0.2%) of solar cells with Cu2O layer electrodeposited at lower pH. The performance enhancement is primarily attributed to the improved electron transport in the Cu2O thin film due to partial merging of grains.