Investigation of underlying corrosion pathways of photo-electrochemical solar cells in electrolytes

In my PhD thesis, I investigate the underlying corrosion pathways of photo-electrochemical solar cells in electrolytes. For a practical implementation of the PEC fully integrated approach, it is crucial to further enhance the system lifetime from the order of hours/days toward months/years of stable hydrogen production.

This can be achieved by electrochemical passivation of the AlInP window layer, the semiconductor-electrolyte interface is the most susceptible to corrosion. The disintegration of the photo-absorbing layers and the consequent decrease of voltage and current have proven to be the most detrimental factors for long-term hydrogen evolution. This pathway can be negligibly small if the photocathode is passivated by a chemically resistant, transparent layer on top of the device.

Typically this is achieved by depositing metal oxides like titanium and aluminum oxide in atomic layer deposition processes. Within the H2Demo project, some promising results have been achieved by this method however, a second option for interface passivation can result in electrochemical deposition of the corresponding elements combined with controlled surface oxidation.

My thesis aims to understand how such (photo) electrochemical layer deposition can be controlled on an atomistic level utilizing Reflection Anisotropie Spectroscopy (RAS). The focus lies on achieving an ultra-thin, well-ordered passivation layer that does not introduce additional resistances but enhances system stability.