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Sol-gel synthesis and spectroscopic properties of thick nanocrystalline CdSe films

: Ptatschek, V.; Schreder, B.; Herz, K.; Hilbert, U.; Ossau, W.; Schottner, G.; Rahäuser, O.; Bischof, T.; Lermann, G.; Materny, A.; Kiefer, W.; Bacher, G.; Forchel, A.; Su, D.; Giersing, M.; Müller, G.; Spanhel, L.


Journal of physical chemistry. B 101 (1997), Nr.44, S.8898-8906
ISSN: 1089-5647
ISSN: 1520-6106
ISSN: 1520-5207
Fraunhofer ISC ()
nanocrystalline; sol-gel; sol-gel synthesis; spectroscopy; Spektroskopie

Two novel metal alkoxide-derived routes ere developed for the synthesis of nanocrystalline CdSe layers with quantum dot sizes between 1 and 4nm. The first route, where cadmium ethoxy-acetate is reacted with bis(trimethylsilyl)selenium in the presence of aminopropyltriethoxysilane (AMEO), yields highly concentrated alcoholic 0.5M sols for direct coatings. The second route allow to grow CdSe clusters by infiltrating the selenium precursor into Cd-enriched organosilicate gel layers. The resulting optically transparent films with thicknesses near 10um (obtained in a single-step coating) were characterized by steady-state optical absorption and photoluminescence spectroscopy, high-resolution electron microscopy (HRTEM), X-ray diffraction (XRD), resonance Raman, and time-resolved photoluminescence spectroscopy. The experimental data reveal the presence of nanocrystals exhibiting a tetrahedral shape. The quantum dot films are strongly fluorescing, with a quantum yield near 10 per cent.