The advent of a new type of nano crystal to overcome the "flicker" strange phenomenon

For more than ten years, scientists have been trying to overcome the strange phenomenon of "flashing" (blinking) in the light of individual molecules, in order to produce continuous light sources. Recently, Rochester (Rochester) scientists have finally found the basic physics behind this phenomenon, and Eastman Kodak (Eastman Kodak), the researchers together to create a sustained luminescent nanocrystals. These findings are no longer the dream of cheaper and more versatile lasers, brighter LED lighting, and the tracking of drugs and cells.

Many molecules and nano crystals can absorb or emit photons, but sometimes they absorb the energy of the photons will be converted into heat rather than radiation in the form of photons away. These "dark" periods and the normal emission period of the random alternating, so that molecules or crystallites look like in the blink. Todd, a professor of chemistry at the University of Romania, Krauss, working with researchers at Kodak, the Naval Research Laboratory and Cornell University, hopes to find new, non blinking nanocrystals.

Model without blinking nanocrystals

The purpose of Krauss et al. Is to find a new kind of low cost lighting material, such as organic light emitting diode (OLED), but there is no such short life and difficult to manufacture. They were synthesized all composed of microcrystalline, and found a flicker phenomenon is not expected, but after 4 hours of monitoring, this new nano crystal no flashing, in contrast, usually flashing in a few milliseconds to minutes break.

After a long study, the researchers concluded that the reason why the flash did not occur was because of the unusual structure of the nanocrystals. In general, the central part of the nanocrystal is a semiconductor core, and the outer layer is coated with another semiconductor shell. In this new crystal, the cadmium and selenium from the core to the shell of zinc and selenium is a continuous gradient change. This gradient inhibits the process of photon radiation, so the crystallite can emit photons steadily and steadily.

Krauss believes that this non blinking nanocrystals will make it easier and cheaper to make lasers and light sources. At present, different colors of the laser must be produced with different materials and processes, with this new nano crystal, a single process can create any color laser. To change the color of the light, engineers only need to change the size of the nanocrystals. In the same way, in the plane of the "brush" different sizes of nano junction microcrystalline, can create a thin paper like display, or with any color to illuminate the walls of the room. See 2009.05 Nature online version.