Sol-gel derived nanocomposite hybrids for full colour displays

This work reports on the photoluminescence and local structure of the inorganic skeleton of sol-gel-derived hybrids, so-called di-ureasils and di-urethanesils. Their organic/inorganic matrix is a siliceous network to which short oligopolyether chains of different lengths are covalently grafted by means of urea and urethane linkages, respectively. Si-29 magic-angle spinning (MAS) NMR spectroscopy clearly establish the presence of essentially two structures, (SiO)(3)Si(CH2)- and (SiO)(2)Si(OH)(CH2)-, surrounding the Si atoms. The luminescence spectra show a broad light emission (2.0-4.1 eV) that appears to be white to the eye as shown by a set of split video images acquired in real time. No intensity degradation is detected under a prolonged irradiation. The ability of tuning the xerogels emission to colours across the (xy) CIE (Commission Internationale de L'Eclairage) chromaticity diagram is demonstrated by changing the excitation wavelength. (C) 2000 Elsevier Science B.V. All rights reserved.