Nanocrystalline CdTe and CdTe(S) particles: wet chemical preparation, size-dependent optical properties and perspectives of optoelectronic applications

Nanocrystalline CdTe and CdTe(S) particles capped at the surface with different thiols (mercaptoalcohols, mercaptoacids, dithiols) have been synthesized by a wet chemical route in water or dimethylformamide and were characterized by UV-Vis absorption and photoluminescence spectroscopy, X-ray diffractometry and high resolution transmission electron microscopy. The size-quantization effect together with the surface chemistry determined the optical properties of the nanoparticles. Room-temperature luminescence (quantum efficiency 3–6%, at appropriate conditions up to 18%) with a maximum depending on the particle size was observed in the visible spectral range. Thin films assembled from CdTe and CdTe(S) nanoparticles have been formed by either casting from concentrated colloidal solutions, by electrophoretic deposition, or by the Langmuir-Blodgett technique. Perspectives of the applications of the nanoparticles incorporated into light-emitting structures and photonic crystals are discussed.