US Patent 7390568 - Exciton separation with core/shell nanocrystals

http://www.freepatentsonline.com/7390568.html

Excitons are formed from bound states of electrons and holes in insulating and semiconducting materials and are often involved in applications involving light sensing, light emission, and photovoltaics. This patent from M.I.T. teaches forming coated nanocrystals in which excitons can be bound via the core and shell of the nanocrystal. Claim 1 reads:


1. A method of preparing a coated nanocrystal comprising:

introducing a core nanocrystal including a first semiconductor material into an overcoating reaction mixture; and

overcoating a second semiconductor material on the core nanocrystal, wherein the first semiconductor material and the second semiconductor material are selected so that, upon excitation of the nanocrystal to form an exciton, one charge carrier of the exciton is substantially confined to the core and the other charge carrier of the exciton is substantially confined to the overcoating.