Quantum dot 'blinking' problem is solved

BOULDER, Colo., Jan. 24 (UPI) -- U.S. physicists have found a way to suppress the blinking problem in quantum dots by bathing them in a chemical solution.

Quantum dots are tiny, semiconductor nanocrystals that are tunable sources of colored light. While used in such fields as biomedical research and cryptography, they have displayed a tendency to blink on and off, which has reduced their usefulness in some areas.

Now scientists at JILA -- a research facility operated by the National Institute of Standards and Technology and the University of Colorado-Boulder -- have found a way to solve the blinking problem by immersing the quantum dots in an antioxidant chemical. The scientists said that reduces the average time delay between excitation and resulting photon emission from 21 nanoseconds to 4 nanoseconds, while reducing the probability of blinking up to 100 fold.

The researchers said their finding could make quantum dots more sensitive as fluorescent tags in biomedical tests and single-molecule studies and steadier sources of single photons for "unbreakable" quantum encryption.

The research by David Nesbitt and Vasiliy Fomenko was detailed in the Dec. 21 issue of the journal Nano Letters.