US Patent 8232722 - Nanocrystal LED with reduced radiative loss

http://www.freepatentsonline.com/8232722.html

This patent from MIT teaches using nanocrystals to form an LED structure including a lightly doped layer to improve the efficiency of photon generation. Claim 1 reads:

1. A light emitting device comprising:

a first charge transporting layer including a first inorganic material in contact with a first electrode arranged to introduce charge in the first charge transporting layer;

a second electrode;

a plurality of colloidally-grown semiconductor nanocrystals disposed between the first electrode and the second electrode; and

a lightly doped layer proximal to the nanocrystals, wherein the lightly doped layer is doped in an amount effective to minimize non-radiative losses due to exciton quenching by unbound charge carriers in the transporting layer.