Wednesday, November 28, 2007

US Patent 7301172 - Sequentially charged nanocrystal LED

In order to produce more efficient LEDs using quantum dots this patent from CalTech teaches separating the electrons and holes injections by using an AC excitation method. Claim 26 reads:

26. A method of emitting light from a light emitting device including a transistor structure formed on a semiconductor substrate and having a source region, a drain region, a channel region between the source and drain regions, a gate oxide on the channel region, and a plurality of nanocrystals embedded in the gate oxide, the method comprising: injecting first type charge carriers into the nanocrystals; and after injecting the first type charge carriers, injecting second type charge carriers into the nanocrystals, such that the first and second type charge carriers form excitons used to emit the light.