Studies On The Design,Synthesis And Properties Of Benzothiadiazole-Based Conjugated Organic Compounds

Compared to inorganic photoelectrical materials, organic photoelectrical materials have the advantages of wide varieties, diversity of properties, being designed and modified easily. Designing and synthesing of organic molecules with excellent photoelectrical properties attracted intensive attention in the development of functional materials. In this thesis, three novel series of conjugated organic molecules with BT and its derivatives, have been designed and synthesized. Their UV absorption, fluorescence emission spectra and electrical properties were studied.In order to increase the electron density and optical properties, a low band gap monomer was introduced into the main chain of fluorene. The molecular design, synthesis, spectroscopic and photophysical characterization of a new solubility polymers incorporating different π-conjugated chromophores are discussed.Alkoxy-substituted2,1,3-benzothiadiazole was prepared and copolymerized with fluorene using Suzuki cross-coupling reactions. By changing the ratio of the donor and receptor units in the polymers, four kinds of polymers were synthesized. Their UV absorption and fluorescence emission spectra were gradually increased as the ratio of low band gap monomer increased in the polymers. PL efficiency going down gradually with the increasing content of the low band gap in the main chain. At the same time their UV spectra indicates the intramolecular charge transfer properties.A new type of2,1,3-benzothiadiazole and its derivatives with electron withdrawing group were synthesized using chemical polymerization method. Based on the with-drawing group, a novel series of typical D-π-A conjugated organic molecules were synthesized by Still cross-coupling reaction. From the UV absorptions of these two kinds of acceptor monomer, we can see that the maximum UV absorption of2,1,3-benzothiadiazoles has obvious red shift than that of alkoxy-substituted2,1,3-benzothiadiazoles, this indicates that the acceptor monomer should have good electron-withdrawing ability and the donor should have a good electron-donating ability in the donor/acceptor heterojunction. In this case, it is possible to increase the charge transfer efficiency in the structure unit, lower the optical band gap and to well match the absorption of sunlight.The UV absorption of PHBT is red shift than that of PBT, this indicates that PHBT has longer conjugated chain than PBT, and the molecular differentiation increased in PHBT.Two novel series of conjugated organic molecules containing2,1,3-benzothiadiazole and its derivatives were designed and synthesized, their UV absorption, fluorescence emission spectra and electrical properties were studied. The results indicate their charge transfer properties and excellent redox behavior and lay a foundation for photoelectrical materials development.