US Patent 7566476 - High spectral purity quantum dots

http://www.freepatentsonline.com/7566476.html

This patent is from M.I.T. and has some relatively early priority (1997) to a method of nanocrystal separation to produce a narrow spectrum photoluminescence from the nanocrystals. Claim 1 reads:

1. A method of producing a population of coated nanocrystals that exhibit photoluminescence having a quantum yield of greater than about 30%, comprising:

synthesizing a plurality of nanocrystal cores made from a first semiconductor material; and

size-separating a select population of nanocrystal cores from the plurality of synthesized cores, wherein the population of coated nanocrystals emit light in a spectral range of no greater than about 40 nm full width at half max (FWHM) when irradiated.