Posted: August 23, 2006

Olive oil for cheap and clean synthesis of quantum dots

(Nanowerk News) Olive oil can be used for cheap and clean synthesis of quantum dots, according to scientists in Germany.
Quantum dots (semiconducting nanocrystals) are used in the production of light-emitting diodes and lasers, and as fluorescent labels in medical imaging. But current methods for making quantum dots are expensive and often use toxic phosphine molecules. This limits the production of the nanocrystals to the milligram scale.
A cheaper and non-toxic alternative has been devised by Sameer Sapra and co-workers at the Ludwig Maximillians University, Munich. Sapra and colleagues used ordinary olive oil as the solvent to make cadmium–selenium quantum dots, avoiding the need to use phosphines. The method could open up possibilities for mass production of the nanocrystals, said Sapra.
Olive oil is made up of fatty acids and other long-chain hydrocarbons. The synthesis works because the hydrocarbons dissolve selenium at high temperatures. Olive oil also contains oleic acid, which acts as a stabilising agent for the reaction.
Paul Mulvaney, a quantum dot expert at the University of Melbourne, Victoria, Australia, sees potential in the discovery. ‘The synthesis provides further flexibility in the design and growth of…semiconductor nanocrystals,’ said Mulvaney.
According to Sapra, the quality of the nanocrystals obtained by this route is the highest yet seen for phosphine-free methods ("Phosphine-free synthesis of monodisperse CdSe nanocrystals in olive oil").
Source: Michael Spencelayh, RSC Publishing