Semiconductor, Electrocatalyst, and Interface Design for Solar Energy Conversion and Storage
May 30, 2013
from 02:00 PM to 03:00 PM
|Where||Engr. IV Bldg., Maxwell Room 57-124|
|Contact Name||Prof. Diana Huffaker|
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Dr. Shannon W. Boettcher
University of Oregon
The conversion and storage of solar energy through water-splitting requires interfacing high-quality semiconductors that absorb sunlight with efficient electrocatalysts that facilitate the multi-electron H2 and O2 evolution reactions. I will first present progress in developing low-cost, scalable, atmospheric-pressure vapor-transport routes to deposit high-quality III-V semiconductors light-absorbers. We grow n- and p-type epitaxial GaAs layers at rates up to ~ 500 nm min-1 from powder GaAs sources. Using simple and rapid photoelectrochemical characterization techniques we demonstrate minority carrier diffusion lengths of up to 3 µm and near-unity internal quantum efficiencies. Remaining challenges in establishing vapor transport as an alternative to metal organic chemical vapor deposition for the growth of low-cost GaAs solar photovoltaic and water-splitting architectures will be discussed.
In the remainder of the seminar, I will present our parallel efforts to understand and optimize oxygen-evolution electrocatalysts composed of first-row transition metal oxides/hydroxides and develop the basic science of integrating such catalysts with semiconductors for solar-water-splitting devices. We developed a precise thin-film quartz-crystal microbalance technique for quantifying activity of electrocatalysts and demonstrated record activity from Ni1-xFexOOH films. Integration of these films with semiconductors yields interfaces with electrical properties that are more complex than traditional metal-semiconductor Schottky junctions. A new theory of adaptive junctions is developed to describe this behavior
Shannon Boettcher is currently an Assistant Professor in Chemistry at the University of Oregon. His research interests center on developing materials for solar energy conversion and storage. Current efforts focus on the synthesis and study of heterogeneous electrocatalysts with precise molecular and nanoscale structures, the development of alternative deposition routes for high-performance III-V semiconductors such as GaAs, and on understanding the details of interfaces between semiconductors and electrocatalysts in oxygen and hydrogen evolving photoelectrodes. He also leads efforts to develop aqueous-solution-processed functional films in the Center for Sustainable Materials Chemistry, an Oregon-based NSF Phase II Center for Chemical Innovation.
Boettcher received his B.A. in Chemistry at the University of Oregon in 2003 where he was a Barry M. Goldwater Scholar. He received his Ph.D. in Inorganic Chemistry with Galen Stucky at UC Santa Barbara in 2008 where he was an NSF Graduate Research and UC Chancellor's Fellow. As a Kavli Nanoscience Institute Prize Postdoctoral Scholar, he studied three-dimensional Si structures for solar energy conversion and storage at the California Institute of Technology working with Nate Lewis and Harry Atwater. In 2010, he joined the Chemistry Department at the University of Oregon and in 2011 was named one of 18 DuPont Young Professors worldwide.