Characterization of sol-gel processed poly(p-phenylenevinylene) silica and V₂O₅ composites using waveguide Raman, Raman and FTi.r. spectroscopy

A composite of poly(p-phenylenevinylene) (PPV) with V₂O₅ is prepared through sol-gel processing and compared with the corresponding composite with silica. The effective conjugation length as determined by the band gap remains the same when V₂O₅ is chosen as a dopant, whereas the effective conjugation length is reduced in the PPV/silica composite. These composites exhibit good optical quality and show promise for optical waveguiding. The waveguide Raman spectra of these composites can be easily obtained. The refractive index of the PPV V₂O₅ composite is higher than that of the PPV/silica composite. Furthermore, the Raman spectra do not indicate any existence of chemical bonds between the vinyl group of PPV and the glassy matrix (silica oxide or V₂O₅). The sol-gel processed PPV V₂O₅) composite also exhibits a larger χ⁽³⁾ value than that of the PPV/silica composite.