Communication—Texture and Bandgap Tuning of Phase Pure Cu2O Thin Films Grown by a Simple Potentiostatic Electrodeposition Technique

Highly textured phase pure Cu _2 O thin films have been grown by a simple electrodeposition technique with varying deposition voltages (−0.3 to −1.0 V). The surface morphology characterized by Scanning Electron Microscopy (SEM) revealed that the deposited thin films coherently carpet the underlying substrate and are composed of sharp faceted well-defined grains of 0.5–1.0 μ m sizes. XRD analyses showed that all films are composed of polycrystalline cubic Cu _2 O phase only and have average crystalline domain size in the range of 30–73 nm. The preferred crystalline orientation of phase pure Cu _2 O films was found to be changing from (200) to (111) with increasing cathodic voltages and showed the highest (111) and (200) crystalline texture coefficient while growing at −1.0 and −0.8 V respectively. The optical bandgap of the as-grown samples was calculated in the range of 1.95–2.20 eV using UV–vis Transmission data. The performance of Cu _2 O/FTO photocathodes was tested by estimating LED “ON/OFF” modulated surface photovoltage into a photoelectrochemical cell at a zero bias.