This Small Business Technology Research (SBIR) Phase I project will demonstrate a spectral down-converter based on metal ion-doped nanocrystalline quantum dots to increase the efficiency of polycrystalline silicon solar cells. Attempts to add a luminescent spectral down-conversion layer to semiconductor solar cells to shift inefficiently-utilized light below 500 nm in the solar spectrum to longer wavelength have been made over several decades because of predicted relative efficiency gains of 10-20%, a very significant improvement. No practical device has resulted because of the very high performance requirements for the emissive over-layer. Manganese-doped zinc selenide nanoparticles exhibit little absorption longer than 500 nm, yet luminescence with high efficiency in a single band near 600 nm, thus eliminating both optical filtering and luminescence reabsorption. The objective of this project is to evaluate this material?s potential to be a practical spectral down-converter. This involves modeling calculations using solution data as input, measurement of actual performance gains using liquid-reservoir down-converter plus solar cell, and preparation of concentrated thin solid films and their photophysical evaluation. It will then be possible to determine the efficiency gains that can be expected from an integrated thin-film down-converter/solar cell module. The broader impacts/commercial potential of even small improvements in the efficiency of polycrystalline silicon solar cells, which represents a mature technology are very difficult and costly to realize. Yet the advantages of improving their performance is potentially enormous, both commercial and societal, given their current and anticipated increased utilization. Therefore a gain in efficiency on the order of 10% (relative) would have a large commercial impact, especially if it can be obtained from a fairly simple and inexpensive add-on layer. "This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
