Materials World Network: Nanostructured Materials for High-Efficiency Solar Energy Harvesting

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TECHNICAL SUMMARY:With support from the Division of Materials Research, scientists at the University of Texas at Austin (UT Austin) will collaborate with the Clausthal University of Technology (TU Clausthal) to explore materials, processing, and device technologies for high-efficiency photovoltaic devices and solar cell assemblies that can provide optimal performance under a broad range of spectral illumination conditions, as required for applications such as concentrating photovoltaics. Concepts for materials and band-structure engineering to realize high open circuit voltages simultaneously with high photocurrent in quantum-well solar cells using GaAs/InxGa1-xAs1-ySby and GaAs/InxGa1-xAs1-y-zSbyNz heterostructures will be combined with the use of sub-wavelength-scale metal/dielectric structures for long-wavelength light trapping in thin-film semiconductor layers, enabling increased absorption in the quantum-well regions. Epitaxial growth and basic structural and optical materials characterization at TU Clausthal will be combined with heterostructure modeling and design, materials and device processing, and optical and electrical characterization at UT Austin to develop a comprehensive understanding of epitaxial growth, material quality, optical properties, and carrier transport processes, enabling optimization of both optical absorption and photogenerated carrier collection as required to realize the very high power conversion efficiencies predicted for such devices. In addition, "metasurface" structures based on multiple layers of metal nanostructure arrays will be designed, fabricated, and characterized at UT Austin using chemically synthesized metal nanoparticles and solution-based deposition and assembly techniques developed at TU Clausthal. Appropriately designed, these structures will provide wavelength-selective reflectance and transmittance robust to variations in polarization and angle of incident light, and are expected to enable powerful approaches for spectral splitting of sunlight in high-efficiency solar cell assemblies. The synthesis and fabrication approaches used will enable large-area fabrication on non-planar and flexible surfaces as required for applications such as wavelength-selective focusing of sunlight. Photovoltaics and renewable energy concepts will be incorporated into undergraduate education at levels ranging from a required freshman introductory course to senior-level design projects at UT Austin. NON-TECHNICAL SUMMARY:Researchers at the University of Texas at Austin (UT Austin) will collaborate with the Clausthal University of Technology (TU Clausthal) to explore materials and manufacturing technologies for high-efficiency conversion of solar power (sunlight) to electrical power. Emphasis will be placed on technologies that enable large-scale conversion of solar into electrical power by focusing sunlight from a large area onto a small, very efficient solar cell. This approach will allow the use of nanoscale quantum semiconductor structures to increase the efficiency of the solar cell, and by concentrating sunlight onto a small area. it can dramatically reduce the usage of rare and expensive elements and energy-intensive manufacturing processes in solar power systems. A strong educational component, incorporating freshman electrical engineering pedagogy and mentoring as well as early introduction to concepts for solar and renewable energy, development of senior-level design projects relevant to the proposed research, and involvement in research of undergraduates, particularly from groups traditionally underrepresented in science and engineering, will be implemented at UT Austin. The collaboration between UT Austin and TU Clausthal will provide graduate students with direct involvement in international research activities and exposure to the increasingly international context of scientific research.