US Patent 7935419 - Thick shell nanocrystal quantum dots

http://www.freepatentsonline.com/7935419.html

This patent from Los Alamos National Security teaches a way to increase the stability and decrease blinking in semiconductor quantum dots by using multilayer outer shells. Claim 1 reads:

1. Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, wherein the outer shell comprises at least seven monolayers of an inorganic material, wherein at least one of said monolayers comprises CdS, and wherein at least 30% of the quantum dots have an on-time fraction of at least 0.80 for a period of at least 10 minutes.