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 diffe rent thiols (mercaptoalcohols, mercaptoacids, dithiols) have been synthesiz ed by a wet chemical route in water or dimethylformamide and were character ized by UV-Vis absorption and photoluminescence spectroscopy, X-ray diffrac tometry and high resolution transmission electron microscopy. The size-quan tization effect together with the surface chemistry determined the optical properties of the nanoparticles. Room-temperature luminescence (quantum eff iciency 3-6%, at appropriate conditions up to 18%) with a maximum depending on the particle size was observed in the visible spectral range. Thin film s assembled from CdTe and CdTe(S) nanoparticles have been formed by either casting from concentrated colloidal solutions, by electrophoretic depositio n, or by the Langmuir-Blodgett technique. Perspectives of the applications of the nanoparticles incorporated into light-emitting structures and photon ic crystals are discussed. (C) 2000 Elsevier Science S.A. All rights reserv ed.