Influence of ITO Electrode Surface Composition on the Growth and Optoelectronic Properties of Electrodeposited Cu2O Thin Films

Morphological inhomogeneity between electrodeposited cuprous oxide (Cu2O) thin films on nominally equivalent tin-doped indium oxide (ITO) electrodes under identical deposition conditions is reported. Dependence of the Cu2O photocurrent generation ability on thin-film morphology is also described. Films exhibiting compact, polyhedral crystallites produce short circuit photocurrents more than 10 times greater than those consisting of sparse, dendritic crystallites. A correlation between the ITO surface stoichiometry and the resulting Cu2O film morphology is established using X-ray photoelectron spectroscopy for identification of the ITO electrode surface chemical states. Variation in the Sn/In atomic ratio up to 33% is measured at the surfaces of ITO substrates from the same supplier lot, highlighting the importance of thorough electrode characterization prior to electrodeposition to obtain repeatable Cu2O performance for energy conversion applications.