Lifetime of Triplet Excitons Now Raised Six Folds

By CIOReview | Wednesday, January 27, 2016

FREMONT, CA: Excitons are the electron sets formed in semiconductor nanocrystals, upon absorption of light, whereas, Triplet excitons, are about six orders greater in magnitude than that of singlets. They are generally confined to the material in which they are generated, but they are spread throughout organic and inorganic semiconductors. However, in a recent development, a group of analysts from North Carolina State University have been able to exhibit the exchange of triplet exciton vitality from semiconductor nanocrystals to surface bound sub-atomic acceptors. The findings will go a long way in amplifying the lifetime of the initially arranged energized state as well as developments in solar energy conversion, photochemical synthesis, optoelectronics, photodynamic therapy and many more.

Utilizing most semiconductor nanocrystals as photosensitizers lies in their short energized state lifetime, which render them deficient to drive photochemical responses. In this context, to find out whether it is conceivable to broaden the semiconductor nanocrystal excited state lifetime, Felix Castellano, Chemistry Professor, North Carolina State University along with post-doctorate Cedric Mongin and Graduate student Sofia Garakyaraghi, used Cadmium Selenide (CdSe) nanocrystals. CdSe was initially prepared by Prof. Mikhail Zamkov and his graduate student Natalia Razgoniaeva at the Bowling Green State University. The group replaced some of the oleic acid capped Cadmium Selenide (CdSe) nanocrystals with the molecular triplet acceptor 9-anthacenecarboxylic acid (ACA). The result achieved was that the exciton created in the CdSe is modified to the ACA, molding a sub-nuclear triplet exciton with a millisecond lifetime.

Castellano stated that the advantage of deciphering the exciton far from the nanoparticle surface, rather than including the nanoparticle itself in the chemical reactions, would not only save the nanoparticle from deteriorating, but help in absorbing light and enhancing its vitality.