Upconverting Films

The rapid proliferation of infrared lasers in armed services generates an immediate need for new infrared detectors with high sensitivity, selectivity, resolution, and low production cost. Currently used semiconductor-based infrared detectors have low quantum efficiency, high dark counts, and need cryogenic cooling. An alternative approach is to upconvert infrared lights into visible lights that can be detected by silicon Avalanche photodiodes (APDs) with much lower noise and higher efficiency. Current phosphor screen used in infrared detection device usually consists of upconverting phosphor with a mean size between 3 to 10 microns, and the light generated scatters over and results in loss of light output, transparency, and spatial resolution. In phase I, we developed upconverting nanophosphors with high upconversion efficiency and pure color emissions, and fabricated transparent upconverting films by incorporating these nanocrystals into polymers. This Phase II program will continue to develop upconverting nanophosphors and nanocomposite films with desired features of high infrared sensitivity, selectivity, transparency, and appropriate refractive-index (to effectively extract the generated emissions). Using the nanocomposite upconverting films, prototypes of highly sensitive, compact, lightweight, and low-cost infrared detector will be fabricated