Current white light-emitting diodes (LEDs) consist of a combination of monochromatic materials which together emit white light. White light-emitting nanocrystals overcome this drawback as they are synthesized as a single component system that emits pure white light. Their fluorescence quantum yield, however, is only 8–9 %, which is too low for commercial use.
Researchers at Vanderbilt University and Oak Ridge National Laboratory, both Tennessee, USA, have shown how simply treating cadmium selenide nanoparticles with formic acid increases the material’s fluorescence quantum yield to 45 % allowing them to generate bright, white light. The same boost can be achieved with other carboxylic acids and the scale of the brightening correlates with the length of the alkyl chain. The phenomenon persists for several days and the team hints that it could find practical use in solid-state lighting applications.
- Bright White Light Emission from Ultrasmall Cadmium Selenide Nanocrystals,
T. E. Rosson, S. M. Claiborne, J. R. McBride, B. S. Stratton, S. J. Rosenthal,
J. Am. Chem. Soc. 2012.