Bifunctional dimer and polymers for photorefractive applications

We present the electro-optic, photoconductive and photorefractive characterization of a novel organic photorefractive structure. It is composed of a bifunctional dimeric molecule combining both photoconduction and electro-optic properties. This low molecular weight material is a glass, showing a glass transition temperature (Tg) at 27 degrees C. Doped with (2,4,7-trinitro-9-fluorenylidene)malononitrile (TNFDM) as photosensitizer (1% wt), this dimer exhibits 200 cm-1 photorefractive gain at 633 urn for 50 V μm-1 electric field applied. Compared to usual doped polymers which generally show inhomogeneities in the mixtures, this material presents good optical quality thanks to its monophasic character. A serie of functionalized copolymer has also been synthesized, in which the ratio of the chromophore moieties over the charge carrier moieties was varied. These copolymers show photoconductivity but no photorefractivity.