Photoelectrochemical Enhancement of Cu 2 O by a Cu 2 Te Hole Transmission Interlayer.

Cuprous oxide (Cu ₂ O) films are electrodeposited on fluorinated tin oxide (FTO) substrates with controlled crystallographic orientation and optimized film thickness. The Cu ₂ O films exhibit a (100)-to-(111) texture change and a pyramid-to-cuboidal crystallite morphology transformation by increasing the electrodeposition current density. The cuboidal crystallites enclosed by (100) sidewalls and (111) truncated surfaces demonstrate better photoelectrochemical property than the pyramid crystallites. By introducing a copper(I) telluride (Cu ₂ Te) layer in between Cu ₂ O and FTO, the photocurrent density increases 70% for the (111)-textured Cu ₂ O film in a 1 M Na ₂ SO ₄ solution under AM1.5 G illumination. The enhancement is mainly attributed to the improved separation of photocarriers in the illuminated Cu ₂ O film by pumping hole carriers to the Cu ₂ Te layer. In contrast to typical electron pathway management, this study provides an alternative route to improve the photoelectrochemical performance of Cu ₂ O-based photocathodes through hole pathway modification.