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

Explore Advances in Photoconductive AFM Research

In this webinar, PC-AFM for Solar Fuels Research: Nanoscale Charge Transport in Water Splitting Photoanodes, Dr. Francesca Toma gives a short overview of the ongoing research projects on solar energy conversion in her group.

Dr. Johanna Eichhorn then focuses on the nanoscale characterization of BiVO₄ - a highly interesting semiconductor light absorber for solar water splitting.

In their discussion, our speakers cover:

• 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.  

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

1. Contact formation between the nanoscale probe and the semiconductor; and
2. Chemical environment on nanoscale transport measurements of PEC devices.

For the first time, they have 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.

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This webinar was presented on: December 6, 2018