MEDIA MATTERS: UNIVERSITY OF ARKANSAS RESEARCHERS FIND EFFECTIVE SOLVENTS FOR NANOCRYSTAL FORMATION

FAYETTEVILLE, Ark. — University of Arkansas researchers have used new solvents to create safe, inexpensive, high-quality semiconductor nanocrystals for use in industry.

Their work appears as a "Hot Paper" in the current issue of Angewandte Chemie, a leading international chemistry journal.

The article, authored by Xiaogang Peng, assistant professor of chemistry and biochemistry, and W. William Yu, postdoctoral research associate, was chosen as a "Hot Paper" for its importance in a rapidly evolving field of high current interest and appears as a communication in the journal.

In the article, the authors present a new approach for developing synthetic chemistry to produce high quality semiconductor nanocrystals.

Because high quality nanocrystals are not readily available, the need for safe, simple, and inexpensive synthetic methods is of interest to scientists working in many different fields, including materials sciences, biomedical sciences, and the physical sciences.

In the past ten years, all relatively successful synthetic methods for creating semiconductor nanocrystals have been based on carefully selected coordinating solvents. The research of Peng and Yu shows that non-coordinating solvents make a better media for the synthesis of colloidal semiconductor nanocrystals.

"The molecules of the non-coordinating solvents are chemically inert to the metal ions and the resulting nanocrystals," said Peng. This means that scientists can "tune" the chemical binding status of the metal ions using binding elements in the non-coordinating solvents. Thus, the chemical reactivity of the metal ions can be fine-tuned to meet the desired balance between the nucleation-the stage generating seeds for the resulting nanocrsytals-and the growth of the seeds generated in the nucleation step.

This allows researchers better control over the formation of nanocrystals of uniform size.

"Many properties of semiconductor nanocrystals, including their emission colors, are strongly size dependent," Peng said. "As a result, it is necessary to synthesize nanocrystals with nearly monodisperse size distribution in order to take full advantage of these novel materials."

The flexibility provided by this approach opens possibilities for developing "greener," cheaper and simpler synthetic schemes for producing important high quality nanocrystals.

Angewandte Chemie is the only journal in the field to have a stimulating mixture of review articles, highlights and short communications. The communications, which are selected by a review board of leading scientists, report on the latest research results, making the journal indispensable to the chemist who wants to stay well informed. The journal also regularly publishes Nobel lectures in chemistry and related fields.

The article is called "Formation of High Quality CdS and Other II-VI Semiconductor Nanocrystals in Non-Coordinating Solvents: Tunable Reactivity of Monomers."

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