Photoelectrochemical Schlenk cell functionalization of multi-junction water-splitting photoelectrodes
Erica A. Schmitt, Margot Guidat, Max Nusshör, Anna-Lena Renz, K. Möller, Marco Flieg, Daniel Lörch, Moritz Kölbach, Matthias M. May
Abstract
Solar water splitting has the potential to significantly contribute to future greenhouse-gas-free fuels. In photoelectrochemical water splitting, the solar absorber is in direct contact with the aqueous electrolyte. This enables a higher level of device integration, but it also creates additional challenges when compared to decoupled photovoltaics-electrolysis approaches. Here, we report on the design of a photoelectrochemical Schlenk cell processing routine that allows photoelectrochemical interface functionalization under controlled conditions. Interface inhomogeneities that accelerate corrosion are hereby reduced, while the photoelectrochemical window layer from the functionalization reduces voltage and light absorption losses for the photoelectrode. Applied to a dual-junction GaInP/GaAs photoelectrode, we demonstrate solar-to-hydrogen efficiencies of up to 18.8% on increased electrode areas and longer unbiased electrode lifetimes compared to similar previous work. This general processing approach should be transferable to other systems where photoelectrochemical functionalization with optical in situ control is desirable.