Date : 23/03/2011 à 14:30
Titre : Colloidal quantum dots - known science applied to novel materials.
Intervenant : Pr. Zeger Hens
Provenance : Physics and Chemistry of Nanostructures group, Universiteit Gent, Belgium
Salle : Seminaire (2ieme etage)
Résumé : Colloidal quantum dots are a novel class of nanomaterials showing attractive opto-electronic properties due to quantum confinement. Nevertheless, a surprisingly wide range of chemical and physical properties of colloidal quantum dots can be understood using textbook physical chemistry. In this presentation, we take this point of view to adress four different aspects of colloidal quantum dots. First, we discuss the hot injection synthesis, showing how classical nucleation theory can be reconciled with recent insights in the reaction mechanism to understand the development of the QD concentration and diameter as a function of time. Second, we show how solution NMR provides surprisingly detailed insights in the surface chemistry of colloidal QDs. Third, we show that equilibrium thermodynamics can be used to rationalize the partial charging of quantum dots dispersed in apolar solvent. Finally, the quantum dot absorption coefficient is discussed in the framework of the Maxwell-Garnett effective medium theory.
