Design,Synthesis And Optoelectronic Properties Investigation Of Distyrylarylene And Polycyclic Aromatic Derivatives

In the past twenty years, organic optoelectricial materials have attracted great attentions. On the one hand, organic field-effect transistors have great potentials in film with large area, low cost, flexibility. However, the biggest problem of OFETs is the low mobility at present. The key point is to explore the relationship between crystal structure and performance of device, so as to further study the mechanisms of charge transport. The organic polycrystalline thin film is composed of microcrystalline particles, which have a large number of structural defects and grain boundaries. Hence, they could not respond the intrinsic properties of organic materials. Due to the molecular long-range ordered, avoiding the presence of grain boundaries and minimize impurities and defects, organic single crystals are the best choice for high-mobility field-effect transistor, which can reveal the intrinsic properties of semiconductor materials. On the other hand, the biggest problem of organic light-emitting materials is many organic molecules have strong fluorescence in the solvent, but occuring fluorescence quenching in the solid-state. To a great extent, these limit their applications in light-emitting diodes, biological probes and ion sensors.Based on the above considerations, this thesis is focused on the designing of organic optoelectronic molecules, exploration of the mechanism and commercialized application. We investigate the relationship among different functional groups on the biphenyl skeleton, crystal packing structure and device performance; device performance of alkaloids eilatin that is similar to the structure of pentacene; three-dimensional anisotropy of single crystal devices and charge transfer mechanisms; the mechanisms of AIEE and the application in Cu2+sensors. The main contents are as follows:1. By changing the substituent groups, we designed and synthesized a series of Distyrylarylene derivatives, which were fabricated into thin-film field-effect transistor devices. The device of BNVBP has the highest mobility of0.25cm2/V>s. A highly ordered thin film was prepared by changing the evaporation process. It leaded to high device performance with mobility of0.4cm2/V>s. We discussed the reason from molecular packing structure, intermolecular force and film crystallinity. Then on this basis, we have synthesized alkaloid derivative eilatin with larger conjugated system, and studied the relationship between thin film device performance and crystal packing structure.2. Using the above distyrylarylene derivative of BNVBP, the single crystals of two different morphologies were grown by dual-zone tube furnace. Single crystals of two different morphologies were caused by different growth orientation of the molecules on the substrate, which were proved by XRD, SEM and TEM. The single-crystal field-effect transistor devices were fabricated by organic single crystal mask technology. The three-dimensional anisotropy of single crystal was measured for the first time. The highest mobility of the device is2.49cm2/V>s. The relationship among device performance, charge injection and transport, crystal structure was discussed in detail. The results are great help for the designing of field-effect transistor materials and the fabrication of devices.3. Based on the theory of fluorescence quenching in solid, two compounds TBBH and TBBF with aggregation induced fluorescence enhancement were designed and synthesized. By analysing of their UV absorption and fluorescence emission spectra, we found that the new emission peak appeared accompanied with aggregation-induced fluorescence enhancement. It suggested that the molecular conformation had been changed. Therefore, we build a theoretical model for excited-state proton transfer, which was proved by the solvent effect, pH effect, NMR spectra, IR spectra, HOMO-LUMO energy orbits and crystal structure. The model not only elaborate on the process of proton transfer and conformational changes in transition state, but also successful explained the reason of the AIEE effect of TBBH and TBBF.4. Due to the unique molecular structure of compound TBBH, metal ion sensors were explored. We found that TBBH has ability of detecting Cu2+with characteristics of naked eye visualization, single selective, high sensitivity and response time. The structure of complex and the mode of combination TBBH with Cu2+were confirmed by titration reactions, theoretical calculations and spectroscopic studies.5. Because of the green compound property of TBBH and the detection of Cu2+with the naked eye visual effects, we preliminary fabricated and explored Cu2+test strip, which had achieved good result.