Preparation And Optical Properties Of Organic/Inorganic Hybrid Fluorescence Coating By Sol-Gel Technology

Silica gels have lots of unique capabilities, nicer heat-insulating property, low density with porous structure, good transparency, low reflect index and so on. It is used in many fields as optics, catalysis, sensor, high-energy physics, and mechanism.The sol-gel process was an effective and feasible method in the preparation of organic dyes doped inorganic matrix, which promoted the research of organic-inorganic optical composite system. In present, a number of organic dye molecules have been successfully incorporated into silica matrices by the low-temperature sol-gel process. SiO2 matrices network is goodish"cage"in which the dye doped, but pure SiO2 coating is generally considered to have a porous structure4 with a lot of Si-OH groups in which fluorescence of dye molecules quench easily because of collision.In this paper silica antireflective coatings were prepared by sol-gel method. The influence of silica concentration on the transmittance of the coatings, and the dip-coated withdrawal rate on the transmittance and surface roughness of coatings were studied. Methyl silicone (MS) was selected as the organic binder during the sol-gel process. Our work has been focused on a new composite network system, which comprises SiO2 sol and MS, and that the fluorescein can be doped in a composite system and are coated as a thin film. The fluorescein doped SiO2/MSO coating was investigated with SPM, UV-V and fluorescence analysis for its optical properties. The results showed that the fluorescein doped SiO2 coating which was excitated by 350～450nm wavelength give an emission spectrum with maximum wavelength at 520 nm. The fluorescence intensity of SiO2/MSO coating was 50% stronger than the common SiO2 coating. Accelerated aging test at the temperature of 70℃showed that fluorescence quenching taking place considerably beyond 20 days, a reduction of more than 70% was observed for the fluorescence intensity of SiO2 coating, on the other hand, the reduction of fluorescence intensity of SiO2/MSO coating was only 15% after 20 days.