Properties of CdSe nanoparticle films prepared by chemical deposition and sol-gel methods

CdSe nanoparticle films were prepared by chemical solution deposition and formation in a silica sol-gel matrix. X-ray powder diffraction and transmission electron microscope measurements confirmed a cubic crystallographic structure of the nanoparticles, with mean diameter varying from 4 to 20 nm, The absorption and photoluminescence spectra of the smaller crystals were strongly blue-shifted due to size quantization. This Letter focuses on the study of a non-excitonic emission band, which can be associated with surface states. The results indicate that this band involves the recombination between shallow trapped electrons and deep trapped holes, with a donor-acceptor-like recombination and are analyzed in terms of the configuration coordinate model. The CdSe nanoparticles prepared by the two different methods showed essentially the same optical behavior. (C) 1998 Elsevier Science B.V. All rights reserved.