Ultrathin Lutetium Oxide Film as an Epitaxial Hole-Blocking Layer for Crystalline Bismuth Vanadate Water Splitting Photoanodes

Here a novel ultrathin lutetium oxide (Lu2O3) interlayer is integrated with crystalline bismuth vanadate (BiVO4) thin film photoanodes to facilitate carrier transport through atomic-scale interface control. The epitaxial Lu2O3 interlayer fabricated by pulsed laser deposition features very few structural defects at the back contact of the heterojunction, and forms a unique band alignment that favors photohole blocking. An optimized interlayer thickness of 1.4 nm significantly enhances charge separation efficiency and photocurrent. Combined with photoelectrochemical characterization, solid-state electronic, and localized conductive atomic force microscopy measurements, it is revealed that the Lu2O3 interlayer modulates the electronic conduction pathways along structural grain boundaries and determines the overall device performance. This study sheds light on the nature of interface-engineered carrier transport for efficient photoelectrode heterostructure design.