Authors: D. Segets, R. Marczak, S. Schäfer, W. Peukert
Affilation: Friedrich-Alexander-University of Erlangen-Nuremberg, Germany
Pages: 344 - 347
Keywords: colloidal stability, core-shell model, ZnO quantum dots
ZnO semiconductor quantum dots have attracted considerable attention during the past ten years due to their promising electro-optical properties. Besides fundamental research on the particle synthesis itself, especially the nanoparticles optimization regarding electronic devices or solar cells is increasingly in the focus of interest. However, for the successful incorporation of nanoparticles into electronic devices, stable suspensions and high solid concentrations are required. At first glance the stabilisation of small nanoparticles seems to be rather challenging as the collision events between the particles are supposed to be very frequent due to the strong influence of Brownian motion in this size regime. In contrast, experiments have revealed that ZnO particles in organic solvents around 5 nm in diameter can be stored over months at room temperature without noticeable aggregation. The current work addresses this effect by calculations according to the DLVO theory using a core-shell model which are complemented by experimental observations under different synthesis conditions of ZnO. According to our findings, the primary minimum vanishes for small nanoparticles enabling the re-separation of two particles after their collision. This effect is ascribed to be responsible for the stabilisation of small ZnO quantum dots in ethanolic solution.