PC-AFM for Solar Fuels Research: Nanoscale Charge Transport in Water Splitting Photoanodes

In this webinar, Dr. Francesca Toma will give a short overview of the ongoing research projects on solar energy conversion in her group. Dr. Johanna Eichhorn will then focus on the nanoscale characterization of BiVO₄ - a highly interesting semiconductor light absorber for solar water splitting. Toma and Eichhorn recently performed quantitative analysis of sub-pA photocurrent maps and IV-curves obtained with their Dimension Icon AFM. Specifically, they revealed the critical impact of (i) contact formation between the nanoscale probe and the semiconductor, and of (ii) chemical environment on nanoscale transport measurements of PEC devices.

For the first time, they showed that the charge transport in BiVO₄ photoanodes can be described by the space-charge-limited current model in the presence of trap states. Furthermore, they used complementary pc-AFM and in-situ Kelvin probe measurements to elucidate the influence of chemical interactions of adsorbed oxygen and water on charge transport and interfacial charge transfer of photogenerated charge carriers. Their research revealed that surface-adsorbed oxygen acts as a shallow trap state limiting electronic performance of BiVO₄ thin films.

• Energy conversion of sunlight, water, and carbon dioxide into hydrogen or liquid fuels.

• Photoconductive AFM and in-situ Kelvin probe for investigation of interfacial charge transfer and charge carrier transport in energy materials.

• Leveraging the open AFM architecture to realize photoconductive AFM by implementing a specially designed illumination setup.