| Since the late 1970s, organic electronics has emerged and been developed rapidly. Compared to inorganic materials, organic materials have many advantages, such as low cost, easy to be modified and applications for flexible organic devices. For organic electronics, it involves subjects such as physics, chemistry, biology and so on. With the development of theories about optics and electronics, more and more attention have been paid to materials and devices of organic electronics. Through the unremitting efforts of scientists, lots of devices have been developed, such as organic light-emitting devices (OLEDs), organic field-effect transitors (OFETs), organic photovoltaic cells (OPVs), organic storage devices, etc. Different device has the special requirement for molecular design and minor structural modification can induce major difference on the device performance. In this regard, rational molecular design and the adjustment of intramolecular conjugation and twisting degree are of great importanceIn the first part of this thesis, the author designed and synthesized some polyphenylbenzene based materials including small molecules and polymers. Then organic light-emitting diodes with various sturctures were fabricated to investigate the light-emitting performance of these polyphenylbenzene based materials. In the following part, novel structures of pyrene fused perylene tetracarboxdiimide (PDI) derivatives were synthesized. Also, the corresponding organic field-effect transistors (OFETs) were fabricated. The main contents are as follows:Chapter one:The basic theories and materials for OLEDs and OFETs were introduced. First, the author focused on the fundermental principles of electroluminescence and different light-emitting materials. Then the phenomenan of aggregation-induced emission (AIE) was sketched. Based on these, the potential application of AIEgens (luminogens with AIE active) in electroluminescence was put forward. Also, the device structures and materials of OFETs were reviewed. Finally, the ideas of this thesis were presented.Chapter two:Through a new synthetic approach, by using polyphenybenzene as a platform, novel deep-blue luminogens with AIE active have been designed and synthesized. And most of the luminogens exhibit blue-shifted emissions in films compared to those in solution. The fabricated devices showed good performance. Nondoped devices displayed high performance with external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 2.3%,2.0 cd A-1, and 1.6 lm W-1, respectively, while the CIE coordinates can stay at (0.15,0.08). Through the rational design of the device structure, CIE coordinates of (0.15,0.06) can be realized. Doped devices demonstrated improved performance with EQE and CE of 3.98% and 4.51 cd A-1.Chapter three:The author designed and synthesized copolymers which contains polyphenylbenzene and fluorene (P1), polyphenylbenzene and carbazole (P2), respectively. Through the research of photophysical data and comparison with copolymers contain benzene unit, it can be found that the polyphenylbenzene unit can not only largely improve the solubility, but also effectively inhibit the contaction between polymer chains. Devices results showed that the polyphenylbenzene unit can be used as an effective building block to fabricate polymer with deep-blue emission.Chapter four:With polyphenylbenzene as a platform, through different linkage modes and adjustment of conjugation, four AIEgens with highly twisted structures were obtained. All these luminogens were structurally stable and exhibited typical aggregation induced emission. Thanks to their highly twisted structures, simple organic light emitting devices showed blue to deep-blue emission. The deep-blue emission devices based on mTPE-mTPE exhibited CE of 1.32 cd A-1,while the CIE coordinates were (0.16,0.12), close to our previous report of deep-blue emission through the meta-linkage mode. The results can provide some guided information about the CIE value limit of TPE-based AIEgens.Chapter five:Based on TPA-CN-TPA, an efficient molecule with deep-blue emission, triphenylamine (TPA) unit was intuoduced so as to enhance the hole transporting ability. Nondoped devices showed tunable deep-blue to green emissions. Without the additional hole-transporting layer,3TPA-CN with simple nondoped fluorescence device structure exhibited deep-blue emission and high performance, with the CE of 5.21 cd A-1, EQE of 3.89%, and the CIE coordinates of (0.15,0.14). Also,3TPA-CN can serve as an excellent host for orange emissive PhOLEDs, with a maximum CE and EQE of 57.4 cd A-1 and 18.2%, respectively.Chapter six:Through different linkage modes and the adjustment of conjugation, three AIEgens were constructed by tetraphenylethene and dibenzothiophene-S,S-dioxide (DBTO). DBTO-pTPE displayed good electron-transporting property, while DBTO-MeTPE and DBTO-mTPE showed hole-transporting property and ambipolar transporting capacity, respectively. When used in multilayer OLEDs, DBTO-pTPE exhibited the highest efficiencies with maximum external quantum efficiency of 3.62% and current efficiency of 8.66 cd A"1. Blue emission devices exhibited current efficiency of 6.17 and 3.51 cd A-1 for DBTO-MeTPE and DBTO-mTPE, respectively.Chapter seven:Three pyrene fused perylene tetracarboxdiimide (PDI) derivatives with large π-conjugation were successfully obtained through the Scholl reaction. The different fused mode induced totally different properties. OFET devices based on spin-coated film of bilaterally extension PDI derivative exhibit the hole mobility as high as 1.13 cm2 V-1 s-1 and an on/off ratio of 108 in air. When utilized in optical limiting, it also showed excellent performance.Chapter eight:Eight pyrene fused PDI derivatives with different alkyl chain have been synthesized to investigate the structure-property relationship. The results showed that intrinsic electronic properties of the π-conjugated backbone were not affected by different alkyl chains, but the solid-state properties, such as molecular packing structures, thin-film morphologies were significantly influenced. OFET devices based on spin-coated film of 8 exhibit excellent hole mobility as high as 1.38 cm2 V-1 s-1 in air. |
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