Harvesting solar energy is necessary to meet the constantly growing energy demand. Over the past 20 years, significant interest has focused on developing new types of solar cells. While silicon-based solar cells remain the industry standard, the incorporation of nanomaterials have shown great promise for the development of the next generation of photovoltaic devices. Much of the interest in semiconductor nanocrystals (NCs) results from the unique ability to tune the composition (CdSe, PbS, InSb, etc), size (2-20 nm) and structure (core-shells, nanorods, tetrapods) of the NCs, thus resulting in the ability to synthesize NCs with bandgaps that extend over a broad region of the solar spectrum. Currently, in the majority of nanocrystal-based devices, the NC layer absorbs photons which must then be separated and extracted. Difficulties with interface quality and carrier mobility result in lower conversion efficiencies than in inorganic crystalline devices. An alternative approach utilizes hybrid nanocrystal/silicon structures. In these devices, light is absorbed by the nanocrystals and transferred through radiative (RET) and non-radiative (NRET) energy transfer into the silicon layer where the electron-hole separation and collection occur.1 By utilizing layered NCs structures comprised of smaller (donor) NCs on top of larger (acceptor) NCs, exciton channeling towards the silicon surface can be enhanced through interdot-NRET. Using a layer-by-layer approach, multi-component nanocrystal/silicon heterostructures can be assembled. Through rational design of the silicon-nanocrystal interface and subsequent NC layers, broad sections of the solar spectrum can be harvested resulting in an increase in solar device performance. The effective channeling of emission from the donor to acceptor NCs can be observed through enhanced photoluminescence of the acceptor NCs.1. Nguyen, H. M.; Seitz, O.; Aureau, D.; Sra, A.; Nijem, N.; Gartstein, Y. N.; Chabal, Y. J.; Malko, A. V., Applied Physics Letters 2011,  98 (16).

Assembly of hybrid nanocrystal/silicon structures for light harvesting devices

247th National Meeting (2014)

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