Photoelectrochemical Enhancement of Cu₂O by a Cu₂Te Hole Transmission Interlayer

Cuprous oxide (Cu₂O) films are electrodeposited on fluorinated tin oxide (FTO) substrates with controlled crystallographic orientation and optimized film thickness. The Cu₂O 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 (Cu₂Te) layer in between Cu₂O and FTO, the photocurrent density increases 70% for the (111)-textured Cu₂O film in a 1 M Na₂SO₄ solution under AM1.5 G illumination. The enhancement is mainly attributed to the improved separation of photocarriers in the illuminated Cu₂O film by pumping hole carriers to the Cu₂Te layer. In contrast to typical electron pathway management, this study provides an alternative route to improve the photoelectrochemical performance of Cu₂O-based photocathodes through hole pathway modification.