US Patent 7919012 - Multi-shell dual-emitting nanocrystals

http://www.freepatentsonline.com/7919012.html

This patent from the University of Arkansas is based on a finding that certain by using multiple shells for quantum dot nanocrystals an improvement in the photoluminescence quantum yield can be achieved (from 20% to 50%). Claim 1 reads:

1. A composition comprising core/shell/shell dual-emitting nanocrystals, wherein:

the nanocrystals comprise a core material, a first shell material overcoating the core material, and a second shell material overcoating the first shell material, each of which is independently selected from a II/VI compound or a III/V compound;

the band gap of the first shell material is greater than the band gap of the core material and greater than the band gap of the second shell material; and

the as-prepared dual-emitting nanocrystals exhibit a photoluminescence comprising two bandgap emission peaks.