Webinar: PC-AFM for Solar Fuels Research

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

This webinar is presented by Dr. Francesca Toma and Dr. Johanna Eichhorn from Lawrence Berkeley National Laboratory (LBNL). They are pioneers in characterizing charge carrier transport in energy materials by pc-AFM.
This webinar took place on December 06th 2018

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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.

Key Topics:

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.  

Speakers

Dr. Francesca Toma
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
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.