Ultrafast Carrier Dynamics in Solar Energy Materials
Charge transport in semiconductor materials and charge transfer across interfaces are critical processes in solar cells and other optoelectronic devices. Ultrafast pump-probe spectroscopy enables the measurement of dynamics of photoexcited charge carriers on sub-picosecond to nanosecond time scales. We employ terahertz spectroscopy, time-resolved photoluminescence, and visible transient absorption spectroscopy to probe intraband and interband transitions in semiconductors. We are working to understand the photophysics and carrier transport of systems such as thin films and nanocrystal arrays to provide insight into their application in solar cells.
We are working to improve power conversion efficiency of thin film CdTe solar cells by understanding how material and interface properties influence performance-limiting recombination mechanisms. Increasing efficiency from 22% to 25% for CdTe would have major impact on the future of photovoltaics. This project is funded by the US Department of Energy Solar Energy Technologies Office and is in collaboration with University of Delaware.
Materials Processing for Photovoltaics
Lead halide perovskite thin film solar cells are an emerging technology with efficiencies matching established technologies. Developing high-throughput, roll-to-roll coating methods with material quality rivaling those of slow, batch methods would have great impact on commercialization. This project is funded by the National Science Foundation and is in collaboration with Profs. Fafarman, Cairncross, and Alvarez in our department.
Sustainability of Photovoltaic Systems
Photovoltaics provide green energy compared to fossil fuels, but environmental impacts of their processing must still be considered. We use a framework of life cycle assessment to evaluate material and energy requirements and toxicity potential of lead in perovskite solar cells. This project is funded by the National Science Foundation and is in collaboration with Columbia University.
Also along the lines of sustainability, we are modeling dynamic material flows to understand material requirements and opportunities to develop a circular economy for the scaleup of silicon photovoltaics to meet renewable energy targets. This project is funded by and in collaboration with the National Renewable Energy Laboratory.