Imidazole Fused Polyarenes Based Organic Semiconducting Materials: Design, Synthesis And Properties

Recently, organic semiconducting materials attract much attention due to their light weight, structure designable and low cost. Considering the dominated charge carriers among their films, organic semiconducting materials are divided into hole transporting materials(p-type), electron transporting materials(n-type) or ambipolar materials. These materials can be applied to different areas, such as organic effect transistor, organic photovoltaic cells and so on. Polyaromatic hydrocarbons(PAHs) are a unique family of organic semiconductors with features of large π-electron delocalization, rigid/planar conformation, and high mobility. It enables highly ordered π-π stacking, thus attracts much attention in next generation organic electronics. Therefore, it is very important to design new PAHs and study their application in organic electronics.In this thesis, with a reasonable design and synthetic methodolgy, a series of PAHs with imidazole fused structure as building blocks were synthesized and their physical properties of optics, electrochemistry and thermal stability were carefully studied. The whole thesis mainly includes the following three sections:(1) The imidazole fused polyarenes A~E were synthesized by Still coupling reaction. The solubility was improved by introducing alkyl chains. The addition of group thiophene enhanced the interaction between molecules by sulfur-sulfur weak interaction and π-π interaction, thus improved the device performance. The decomposition temperature of the compounds are over 300 oC, indicating their good stability. HOMO levels of A, B, C, D, E are-5.76 e V,-5.46 e V,-5.80 e V,-5.61 e V,-5.48 e V, respectively, which means that their levels are close to the work function of electrode material. Therefore, it is proved that these compounds are appropriate for organic field effect transistors(OFETs).(2) The imidazole fused polyarenes F-1, F-2, F-3, G were synthesized by Still coupling reaction. The introduction of group diketopyrrolopyrrole constitutes the D-A-D solar cell materials. The decomposition temperature of the compounds are over 300 oC, showing excellent stability. Besides, the materials won’t deteriorate in the air for the low levels. HOMO levels of F-1, F-2, F-3, G are-5.69 e V,-5.33 V,-5.54 e V,-5.41 e V, respectively, which means that their levels are close to the work function of electrode material. Therefore, it is proved that these compounds are right materials for Organic photovoltaic cells(OPV).(3) The imidazole fused polyarenes H was synthesized and used as a chemical sensing probe. Its response towards many metal ions was investigated. H shows relative sensitivity to Hg2+ compared with other 13 kinds of metal ions. From the absorption spectra of view, the detection limit rangs from 5 μM~55 μM. From the emission spectra of view, the detection limit rangs from 1.5 μM~10 μM.The imidazole fused polyarenes A to H are mostly sythesized by Still coupling reaction. This reaction has advantages of simple principle, easy operation and high yield than Suzuki and it is one of the best coupling reactions. These materials have wide application in the field of organic electronics due to good stability, high mobility and ordered π stacking.