Elucidating the Pulsed Laser Deposition Process of BiVO<sub>4</sub> Photoelectrodes for Solar Water Splitting
Moritz Kölbach, Karsten Harbauer, K. Ellmer, Roel van de Krol
Abstract
BiVO4 thin films for use as photoelectrodes for solar water splitting are prepared by pulsed laser deposition (PLD), a powerful technique to synthesize compact multinary metal oxide films with high electronic quality. Here, the PLD process of BiVO4 films by ablating a BiVO4 target is systematically elucidated, with a special focus on deviations from an ideal stoichiometric target-to-substrate material transfer. By correlating the V/Bi ratio of the films with their charge carrier transport properties and photoelectrochemical (PEC) performance, AM1.5 sulfite oxidation photocurrents of ∼2.4 mA cm–2 at E = 1.23 V vs reversible hydrogen electrode (RHE) with stoichiometric films are achieved without any deliberate doping or surface modification. In addition, we prepare BiVO4 photoelectrodes for the first time by alternating the ablation of Bi2O3 and V2O5 targets. This approach is found to be an attractive alternative route to control the cation stoichiometry and produces BiVO4 films that generate AM1.5 sulfite oxidation photocurrents of up to 2.6 mA cm–2 at E = 1.23 V vs RHE. Our results provide important insights into the PLD process of ternary oxide semiconductors and help to accelerate the synthesis and investigation of new multinary metal oxide photoelectrodes.