Photoluminescence-structure relationships in ormosils for integrated optical devices Rute Sá Ferreira, Celso Molina, Karim Dahmouche 1 , Sidney Ribeiro 1 , Rogéria R. Gonçalves 2 , Verónica de Zea Bermudez 3 and Luís Dias Carlos Departamento de Física and CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal 1 Instituto de Química - UNESP, CP 355, CEP 14801-970, Araraquara - SP, Brasil 2 Departamento de Química- FFCLRP- USP- Ribeirão Preto, SP, Brazil 3 Departamento de Química and CQ-VR, Universidade de Trás-os-Montes e Alto Douro, 5001- 911 Vila Real Codex, Portugal ABSTRACT Planar waveguides with low losses in the infrared (from 0.6-1.1 dB/cm) were prepared with sol-gel derived poly(oxyethylene)/siloxane hybrid doped with zirconium(IV) n-propoxide (ZPO) and methacryloxypropyltrimethoxysilane (MAPTMS). The doped nanohybrids were characterized by small angle X-ray scattering, 29 Si nuclear magnetic resonance and photoluminescence spectroscopy and compared with the undoped hybrid material. The results indicate an effective interaction between the zirconium particles and the siliceous nanodomains. INTRODUCTION Sol-gel processing offers a low temperature route for the development of organic- inorganic hybrid (OIH) materials potentially suitable for the production of optical waveguides and functional integrated optical devices at low cost. Short chain di-urea cross-linked poly(oxyethylene) (POE)/siloxane hybrids, named di-ureasils d-U(600) (where 600 represents the average molecular weight of the polymer chains, corresponding to approximately 8.5 repeat polymer units), simultaneously present acceptable transparency and mechanical flexibility leading to easy processing of thick films. d-U(600) is a room-temperature (RT) white light emitter with emission quantum yields around 10 % [1,2]. Another type of attractive hybrid host is that derived from MAPTMS which contains a photopolymerizable organic group that can be easily patterned using ultraviolet light radiation and lithographic techniques. Control over the refractive index of the films can be achieved through the use of a stable zirconium alkoxide- based sol. The combination in a single material of amide cross-linked OIH precursor, MAPTMS and stabilized zirconium alkoxide allows the preparation of planar waveguides with low attenuation around 1550 nm (0.6-1.1 dB/cm). Despite the potential technological relevance of such hybrid materials, the origin of their efficient white-light intrinsic photoluminescence (PL) is not completely clarified yet. With the goal of investigating the PL origin, we examined the influence of the incorporation of zirconium alcoxide and MAPTMS into d-U(600) through PL in steady state and time-resolved modes. The structural features of the samples were also analyzed by 29 Si Magic Angle Spinning (MAS) nuclear magnetic resonance (NMR) and small-angle X-ray scattering (SAXS) in order to elucidate the structure/optical properties relationship. EXPERIMENTAL d-U(600)-ZPO (labeled UZ). A solution of d-U(600), synthesized as indicated elsewhere [3], in ethanol was stirred for 1 hour. ZPO (Zr(OC 3 H 7 ) 4 , ~70% in propanol) and methacrylic acid (MA, H 2 C=C(CH 3 )CO 2 H) - used as ZPO stabilizer - were mixed (molar ratio ZPO:MA=1:1), Mater. Res. Soc. Symp. Proc. Vol. 847 © 2005 Materials Research Society EE10.7.1