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

In this webinar, 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.

They both recently performed quantitative analysis of sub-pA photocurrent maps and I-V curves obtained with their Dimension Icon AFM. Specifically, they revealed the critical impact of:

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

For the first time, they have shown 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.

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 force microscopy 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

This webinar was presented on December 6, 2018.

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