PC-AFM for Solar Fuels Research: Nanoscale Charge Transport in Water Splitting Photoanodes
Explore Advances in Photoconductive AFM Research
In this webinar, our speakers discuss solar energy conversion and demonstrate that the charge transport in BiVO4 photoanodes can be described by the space-charge-limited current model in the presence of trap states.
Webinar Summary
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:
- Contact formation between the nanoscale probe and the semiconductor
- 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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Speakers
Dr. Francesca Toma
Staff Scientist, Chemical Sciences Division at Lawrence Berkeley National Laboratory
Dr. Francesca Toma is a Staff Scientist in the Chemical Sciences Division at Lawrence Berkeley National Laboratory. She is a Principal Investigator and the Coordinator of the Materials Integration Thrust at the Joint center for Artificial Photosynthesis. Her specific research interests lie in the synthesis, characterization, and integration of light absorber/catalyst assemblies, and on the development of in situ and operando microscopy techniques to study energy efficient systems.
Dr. Johanna Eichhorn
Postdoctoral Fellow in the Chemical Sciences Division at Lawrence Berkeley National Laboratory
Dr. Johanna Eichhorn is Postdoctoral Fellow in the Chemical Sciences Division at Lawrence Berkeley National Laboratory. She received her PhD in Physics from Technische Universität München, Germany. Her current research interest is to understand interfacial charge transport in photoanode materials for solar water splitting.