Understanding Photo-conversion Processes in Biomimetic Photoelectrochemical Nanomaterials

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PI: ChoiProposal Number: 1134376Solar cells based on photoelectrochemical conversion of sunlight to electricity suffer from relatively narrow light absorption and cell degradation, which reduces device performance and lifetime. In nature, photosynthesis has solved many of these problems. Photosynthesis is a biologically-mediated photoelectrochemical process for conversion of sunlight into electrons. Natural photosynthesis has perfected robust molecular machineries that enhance photo-excitation energy collection using an array of chromophores that counteract the effect of photo-damage via self-regeneration. The current limitations of photoelectrochemical cells can be better understood and potentially improved by mimicking natural photosynthesis with artificial photosystems. The overall goal of this research is to develop general design rules to build artificial photosystems with improved overall photo-conversion efficiency and service lifetime.This research seeks to mimic the photo-absorption/conversion and self-regeneration processes of natural photosynthesis with synthetic chromophore nanomaterials through biomolecular nanofabrication techniques. Specifically, photo-pigments and quantum wires will be reversibly assembled via programmable DNA molecular recognition techniques, forming photoelectrochemical nanostructures capable of panchromatic absorption and system repair. For example, DNA-based assembly of selective porphyrin chromophores on single-walled carbon nanotubes can interact with G-quadruplexes to facilitate charge transfer at the nanoscale. By this approach, a variety of synthetic photo-conversion nanostructures capable of mimicking the structure and function of natural photosystems will be developed, and their photo absorption and conversion processes will be studied using ultrafast pump-probe measurement of the energy and charge transport processes. This data will be analyzed to elucidate the thermodynamics and kinetics of photo-conversion processes, and generate design rules for constructing artificial photosynthetic units. Broader ImpactsThe proposed activities will couple the research efforts to educational and outreach activities designed to advance the public understanding of artificial photosynthesis. Specifically, hands-on modules for high-school students will be developed for Introduce a Girl to Engineering Day and Discovery Days hosted by Purdue University, and research outcomes will also be featured on nanoHUB, an NSF-funded, Purdue-based nanotechnology website. Female and underrepresented undergraduate students will be recruited for participation in the research through the Women in Engineering and Minority Engineering Programs at Purdue University.