Interfaces for Clean Energy Conversion
The interest and expertise of this group lie at the intersection of materials and interfaces for solar and alkane energy conversion. Our research efforts focus on new understanding of and pathways toward photovoltaics, solar fuels generation, and methan conversion with disruptively high power efficiency, large earth-abundance, or low-cost fabrication. While commercial solar energy conversion is growing at an explosive rate, the basic understanding of the surface chemistry and the optoelectronic processes necessary to develop affordable and sustainable solutions to world's energy need has just begun. As such, we aim to ascertain and influence the arrangement of atoms at interfaces, which largely dictate the underlying physics of solar energy conversion devices. Recent studies include the use of atomic layer deposition to grow hematite (the main component in rust) and nanoscale catalysts for solar fuel production and methane conversion, the stabilization and surface passivation of sulfide-based thin film solar absorbers, and the rational design of multi-gap absorbers for the next generation of photovoltaics.
Jason Avila (Northwestern University)
Matthew Weimer (Illinois Institute of Technology)
Photoexcited carrier dynamics of Cu2S. Recently, there has been a resurgence of interest for stabilizing a Cu2S system owing to its elegant simplicity, extraordinary generation potential, as well as unintentional presence in other thin film photovoltaics. However, stable Cu2S-based device efficiencies approaching 10% free from cadmium have yet to be realized. Recently, we utilized transient absorption spectroscopy to investigate the dynamics of the photoexcited state of isolated Cu2S thin films prepared by atomic layer deposition or vapor-based cation exchange of ZnS. Revealing the effects of grain morphology on the photophysical properties of Cu2S is a crucial step toward reaching high efficiencies in operationally stable Cu2S thin film photovoltaics. (ANL Solar Energy Systems Highlight)
ALD of metastable β-Fe2O3 for solar fuels. Semiconducting thin films suitable for large-scale solar energy conversion applications are limited to a class of materials that are nontoxic, inexpensive, easily processable, and earth abundant. It is, however, possible to broaden or improve the properties of this narrow class of materials through synthesis and utilization of uncommon, metastable phases. We report the growth and photoelectrochemical (PEC) characterization of an uncommon bixbyite phase of iron(III) oxide (β-Fe2O3) epitaxially stabilized via atomic layer deposition on an conductive, transparent, and isomorphic template (Sn-doped In2O3). As a photoanode, unoptimized β-Fe2O3 ultrathin films perform similarly to their ubiquitous α-phase (hematite) counterpart, but reveal a more ideal bandgap (1.8 eV), a ≈0.1 V improved photocurrent onset potential, and longer wavelength (>600 nm) spectral response. Stable operation under basic water oxidation justifies further exploration of this atypical phase and motivates the investigation of other unexplored metastable phases as new PEC materials. (ANL Solar Energy System Highlight)
Atomic Layer Deposition of Water Oxidation Catalyst. Earth-abundant semiconductors capable of directly converting sunlight into fuels may provide a singular solution to solar energy conversion and energy storage. Fuels are a particularly attractive form in which to store renewable energy owing to the high energy density and portability of chemical bonds. Argonne researchers, working with collaborators at Michigan State University, have shown that the efficiency of water splitting with hematite - the most prevalent iron oxide in rust - is dramatically enhanced by additional of an ultra-thin cobalt-based coating. When viewed as a general approach to accelerating the photoelectrochemical conversion of sunlight to fuels this methods paves the way for improvement of a wide variety of catalytically-limited solar fuels reactions. (ANL Solar Energy Systems Highlight)
Martinson and Pellin are 2 of 20 principal investigators in a large collaborative research program conducted through the Argonne Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pellin further serves the Center as Deputy Director. Martinson is also 1 of 17 principal in Inorganometallic Catalysis Design Center, another EFRC. Funding has also been provided by the U.S. Department of Energy, Energy Efficiency and Renewable Energy Office through the SunShot Program. Publications with US and international universities including Northwestern University, Michigan State University, and University of Minnesota have resulted from fruitful collaborations in recent years.
Postdoctoral Positions - A position is currently open for outstanding postdoctoral candidates. The successful candidate will enable next generation solar energy conversion through new intermediate band solar absorbers and thermal photovoltaic design. In collaboration with theoretical and computational colleagues, the appointee will fabricate novel thin film devices as well as advance the basic science of intermediate band semiconductor growth and characterization. Atomic layer deposition, materials synthesis and crystallization, as well as optoelectronic characterization will be required. Previous device experience is preferred, as device design and assessment will be emphasized. Candidates within three years of completion of their Ph.D. are eligible. Candidates within three years of completion of their Ph.D. are eligible. Interested candidates should send a detailed CV, along with a list of publications, to Alex Martinson martinson(at)anl.gov.
There is also always the potential for a postdoctoral position for exceptional candidates with the possibility of fellowship support. For example, current and prior postdocs have received funding through the highly competitive EERE SunShot Fellowship and ANL Director's Postdoctoral Fellowship.
Undergraduate Research Opportunities - Summer internships are available through the Science Undergraduate Laboratory Internships (SULI) Program. Highly motivated students with interest in solar energy technology at the sub-nanometer scale are encouraged to apply and contact us directly.
Faculty Research Opportunities - Selected university/college faculty members may collaborate with DOE laboratory research staff on a research project of mutual interest through the Visiting Faculty Program. Faculty member participants may invite up to two students (one of which may be a graduate student) to participate in the research project.