The influences of post-preparative treatments on luminescence from CdTe nanoparticles

Nanotechnology has seen an explosion of research interest in recent years. Nanoparticles are finding applications in an ever growing list of applications. To further develop these applications an understanding of the properties of a nanoparticle is needed. This thesis prevents an investigation of the photoluminescent properties of CdTe nanoparticles as a function of various post-preparative treatments. Changing the inter-particle distance is found to cause photoluminescence wavelength shifts. These shifts are determined by the amount of energy transferred between nanoparticles. The effects of interparticle distance are seen when a suspension is diluted, re-concentrated or deposited as a thin film. In a thin film format similar effects are seen if the number of layers in a thin film is increased. Changing the temperature of either a thin film or suspension of nanoparticles produces both reversible and irreversible photoluminescence wavelength shifts. The reversible changes are mainly found to be due to the presence of thermally activated trap states within the nanoparticles. Finally, formation of a thin film via the layer-by-layer deposition method is studied. A real time in-situ analysis technique is used to monitor the whole deposition process. The deposition is found to take place in a series of stages with nanoparticles becoming either strongly or loosely bound to the surface. Optical waveguide lightmode spectroscopy is found to be an extremely useful technique for monitoring this thin film deposition as it allows researchers the opportunity to quickly and easily characterize individual experimental setups.