Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Materials

Quantum Dot Mystery Resolved

A secondary phosphine in the starting material seems to be key to forming PbSe nanomaterials

by Celia Henry Arnaud
August 9, 2010 | A version of this story appeared in Volume 88, Issue 32

[+]Enlarge
Credit: Courtesy of Todd Krauss
Yields of PbSe quantum dot synthesis are 10 times higher with pure dioctylphosphine selenide (right) than with commercial TOPSe (left).
Credit: Courtesy of Todd Krauss
Yields of PbSe quantum dot synthesis are 10 times higher with pure dioctylphosphine selenide (right) than with commercial TOPSe (left).

The mechanism of quantum dot formation may not be what people thought, a study reveals (J. Am. Chem. Soc., DOI: 10.1021/ja103805s). A common source of selenium for the synthesis of CdSe or PbSe quantum dots is trioctylphosphine selenide (TOPSe). But when Todd D. Krauss, Christopher M. Evans, and Meagan E. Evans of the University of Rochester combined high-purity TOPSe with Pb(oleate)2, they saw no quantum dot formation. Adding a secondary phosphine to the high-purity TOPSe sped up the reaction rate and caused PbSe quantum dots to form. In addition, TOPSe derived from commercial-grade trioctylphosphine typically used for quantum dot syntheses contains dioctylphosphine selenide as an impurity, which immediately disappears upon combination with a metal carboxylate. The Rochester team suggests that the secondary phosphine may be the actual reactive species in TOPSe, whereas TOPSe itself serves only as a soluble source of selenium that is capable of selenium exchange with more reactive species. The researchers believe their results explain the irreproducibility and poor yields for conventional quantum dot syntheses.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.