SBIR Phase I: Highly Efficient, Long Lifetime, and Inexpensive Nanocrystal Light Emitting Diodes (LEDs)

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This Small Business Technology Transfer (STTR) Phase I project will explore high efficient, long lifetime and inexpensive light emitting diodes (LEDs) based on semiconductor nanocrystals. The fabrication technology of the semiconductor nanocrystal LEDs is very much similar to the one used for the fabrication of polymer LEDs for commercial purposes. As a result, the commercial potential of the nanocrystal LEDs relays mainly on the optical quality of the nanocrystals. This project design adopts two recent technologies, which yields semiconductor nanocrystals with extremely high emission efficiency and exceptional chemical and thermal stability. The dendron ligand technology provides nanocrystals with exceptional stability against the chemical processing and the thermal effect in the operation of the devices. The nanocrystals synthesized using the bright point concept produces unprecedented optical quality, about 80 percent photoluminescence quantum yield, 23-27 nm emission full peak width at half maximum, and tunable emission window from 450-700 nm. With those high optical quality and highly processable semiconductor nanocrystals, it is possible that a new generation of semiconductor nanocrystal LEDs, which have at least compatible performance to the polymer LEDs, but with low cost and continuous tunable and narrow emission profile.The commercial potential of the polymer LEDs and nanocrystal LEDs will highly depend on the lifetime and the cost of the devices. Nanocrystal LEDs possess nearly all of the advantages of polymer LEDs, but with significantly more tunable and narrow emission profile. At this stage, the commercial standard for the lifetime of the polymer LEDs is around several thousand hours. The commercial goal this project is to boost the performance of the nanocrystal LEDs to at least the level of that of polymer LEDs. The usage of those devices is on portable electronic devices, such as portable computer and cellular telephone.