Prof. Jonathan Owen, Columbia University

The coordination chemistry of cadmium selenide nanocrystals

School Colloquium

Surfaces dominate the properties of colloidal semiconductor nanocrystals. Characterizing and controlling surface coordination chemistry is therefore crucial to their application in optoelectronics and fluorescence labeling. I will describe our picture of nanocrystal surface structure as well as a novel ligand exchange technique that allows us to fabricate semiconductor films using solution techniques.  In particular, we have exchanged carboxylate ligands for chloride ligands in the presence of alkylphosphines and prepared thin film transistors with unusually high electron mobilities (8 cm^2/V/sec). In addition, using 31P NMR spectroscopy we monitor the binding and exchange of tri-n-alkylphosphines and can estimate the relative binding affinities of amines, phosphines and phosphine oxides. I will also briefly discuss our work on the structural characterization of large semiconductor molecules or molecular clusters.

For more information contact Prof. Joseph Sadighi (404-385-2244).