US Patent 8197720 - Non-blinking semiconductor nanocrystals

http://www.freepatentsonline.com/8197720.html

Blinking is a problem well known to quantum dots used as biological tags. This patent from Konica Minolta Medical and Graphic teaches a core/shell quantum dot structure which overcomes this problem. Claim 1 reads:

1. Core shell-type semiconductor nanoparticles having an average particle size of from 2 to 50 nm and comprising

an intermediate layer between a core portion and a shell portion,

wherein band gap widths of bulk crystals which have the same compositions as those of the core portion, the intermediate portion and the shell portion, respectively, are in the order of: core portion, shell portion, intermediate layer.