The development of photoelectrodes with high efficiency and low manufacturing cost is of great interest for the production of renewable and green hydrogen through solar water splitting. In this work, we use structural, optical and photo-electrochemical characterizations to study the performance of epitaxial GaAs/Si photoelectrodes. Specifically, we demonstrate that photoanodes composed of epitaxial 1 μm thin films of GaAs on a low-cost Si substrate can produce higher photocurrent than those obtained with more expensive commercial GaAs substrates. From photo-electrochemistry experiments carried out under monochromatic excitation, we show that the enhancement of the photo-current is linked to the optical activity of the two materials GaAs and Si, benefiting both from the photo-generated carriers in the GaAs and Si. This result opens new possibilities for designing efficient and inexpensive dual bandgap photoelectrodes.
Article published in: Solar Energy Materials and Solar Cells