SBIR Phase I: Self-Assembled Nanocrystal Photovoltaic Cells

This Small Business Innovation Research Program Phase I proposal will demonstrate the feasibility of the proposed electrostatic self-assembly (ESA) processes for the large-area and low-cost fabrication of allinorganic nanocrystal photovoltaic (NC-PV) devices. Current limitations for organic PV devices include short lifetime, spectrally limited absorption and low carrier mobilities. The research team has investigated the fundamental physical principles to fabricate the NC photosensitive materials via the ESA process. Through ESA process, the team will develop heterostructural PV devices using NCs such as CdTe, CdSe, PbS, and PbSe with other semiconductor materials of higher mobility, such as porous silicon (pSi), amorphous silicon (a:Si) and nanocrystalline silicon (nc:Si) to reduce the carrier recombination. The team will also investigate the heterogeneous selections of nanocrystals to form a multiheterojunctioned tandem NC-PV device to fully use solar AM1.5 spectrum. In addition the company's QD-PMMA composite will be used to fabricate the top films of the NC-PV devices as down-converters to shift the incident high-energy photons toward lower energies for which the NC-PV cells work more efficiently. A broad band of applications of the proposed PV devices include solar cells, spectroscopy, photography, analytical instrumentation, optical position sensors, beam alignment, surface characterization, laser range finders, optical communications, and medical imaging instruments. Currently, the production of electricity from photovoltaic devices is uneconomical compared to fossil fuel or nuclear sources except for applications located off the electrical grid. The company's research in the PV field has shown promise in producing cells of acceptable efficiencies at significantly reduced cost using organic, inorganic and conductive polymer materials. A revolutionary breakthrough in reducing the costs of PV cells may be achieved if the semiconductor is deposited from solution onto large flexible substrates in roll-to-roll coating machines. Manufacturing costs would be much lower because roll-to-roll coaters use very little energy and have an exceptionally high throughput. Installation costs would be lower because lightweight flexible PV cells could be handled more easily than heavy silicon panels.