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.
Keywords: carrier recombination; hole transmission; photocathode; photoelectrochemical; water splitting.