Synthesis of organic molecules for photorefractive applications

This dissertation describes the synthesis and physical properties of a variety of organic molecules including dyes, charge transport agents, plasticizers and liquid crystals for photorefractive (PR) applications and other possible applications. It was anticipated that these new materials would provide good photorefractive gain, fast response time and good chemical and morphological stability.; A comprehensive introduction to organic photorefractive materials is provided in Chapter one.; Chapter two deals with the synthesis, characterization and structure optimization of DCDHF (dicyanomethylenedihydrofuran) chromophores. Their use as monolithic PR materials is possible because of the glass forming properties. The dimer aggregation of DCDHF dyes was studied both in solution and in film. A study of figure of merit and photorefractivity showed that DCDHF-containing monolithic glasses and composites are promising PR materials that exhibit high photoconductivity, birefringence and two-beam coupling gain.; In chapter three, we have synthesized multifunctional organic glasses that combine the functions of optical nonlinearity, birefringence and charge transport into a single molecule by attaching an NLO chromophore to a charge transport moiety. Our photorefractive studies focused on DCST-DCTA (covalently linked dicyanostyrene and dicarbazoletriphenylamine derivatives) glasses because of their good photostability and morphological stability. Photorefractive performance was demonstrated to be dependent on the exact identity of the linkage between the chromophore and the charge transporter.; In chapter four, for the purpose of photorefractive trapping mechanism studies, a series of carbazole derivatives were made for the use as plasticizers in photorefractive composites. A charge transporting homopolymer of 9-vinyl-3,6-di-tert-butylcarbazole and its copolymer with N-vinylcarbazole were prepared in an attempt to solve the photostability problem in an AODCST/PVK/C₆₀ (AODCST refers to 2-[4-bis(2-methoxyethyl)amino]benzylidenemalononitrile) PR composite.; In chapter five, a comprehensive synthesis of differently reduced 4-methylenepyridine (MRP) chromophores was described. In each class of material, chromophores with different substitution on nitrogen and on methylene were prepared for achieving mesogenic phases. Flexible chains on both termini of the rod-like structure seemed to benefit the liquid crystal formation. The synthesized MRP chromophores are potentially useful in photorefractive materials and possible other electrooptical applications.