Enhancement of Photoaffinity and Charge Carrier Collection in Mixed Metal Oxides Photo-Anodes Implemented with Plasmonically Active Metal Nps

An effective solar light-driven water splitting in photo-electrochemical devices requires use of materials which combine both high photo-conversion efficiency and long term stability goals. For the latter reason the choice of the suitable systems is restricted to the semiconducting oxides that, in most cases, do not undergo photo-corrosion in aqueous solutions but which are also able to absorb efficiently the visible light. The low optical absorption coefficients near the fundamental band edge, which determine the extent of solar light absorption by many photo-anode materials, are the critical factors for a number of semiconductors characterized by an indirect optical transition. This is also the case of n-type semiconducting WO₃ or Fe₂O₃ responding to the blue, respectively, green part of the solar spectrum for which the optical absorption depths exceed the minority charge carriers collection distances.Therefore, incoupling of light into semiconductor films by scattering from plasmonic nanostructures and/or resonant coupling of  the plasmonic near field to the semiconductor,  have a potential to improve the effectiveness of the photocurrent spectral response of the employed photoanode. The results regarding the improved light absorption and charge collection in doped and/or mixed semiconducting oxide photo-anodes will be presented.