| Poly(norbornene-dicarboximide) deriatives synthesized by ring-opening metathesis polymerization (ROMP) possess high glass transition temperature (Tg>200℃), and they were applied in many fields, such as high dielectric material, organic solar cell, and organic light emitting diode. The unsaturated carbon-carbon double bond in the main chain of polymers result many microstructures, such as trans or cis microstructure, and different tacticity. Different microstructure corresponds to different property. To obtain good property of materials, it is very meaningful to control their microstructure.Organic light emitting diodes (OLED) have many advantageous properties, such as low-drive voltage, high brightness, high luminescent efficiency, wide viewing angle, fast response speed, easy to fabricate, cheap, and flexible display. These advantages made OLED become a kind of very promising display device. To obtain full color display, materials that can emit three primary (blue, green, red) colors are required. Incorporating donor-acceptor to molecules is a common way to tune emission color of material because of the donor-acceptor induced intramolecular charge transfer (ICT). Different intensity of ICT would result different energy in excited state and different radiation energy to come back to ground state. In addition, the donor-acceptor structure would change the energy level to match the working potential of anode and cathode better. It is of a certain significance to design and develop new donor-acceptor material and investigate their photophysical, electrochemical, and thermal property to realize their application in OLED.Firstly,3,6-disbstituted carbazole trimer were linked with aldehyde, pentafluorophenyl and dicyanovinyl to form donor-acceptor structure, respectively. Then these donor-acceptor structures were combined with norbornene-dicarboximide. Carbazole trimer possesses a longer conjugated length and stronger electron donating ability than carbazole, and it can form strong intramolecular charge transfer with acceptor to ensure different color emission. In addition, incorporating 9-ethylhexylcarbazole moiety to 3 and 6 positions of carbazole would increase the solubility of monomers and polymers. Monomers M1-M4 were synthesized and the 1H NMR,13C NMR, FT-IR, and MS spectra confirm the formation. ROMP of M1-M4 was investigated. M1-M3 can be polymerized with high yield, however M4 was difficult to polymerize with monomer conversion of only 15%. The endo-configuration of norbornene-dicarboximide has lower activity of ROMP than exo-configuration, so exo-M4 was synthesized for comparison and it was polymerized at the same condition as M4 with higher monomer conversion of 72%, but monomer still can not be fully converted. Because of the difficulty to isolate P4 from it’s monomer, P4 was obtained indirectly from P2. The microstructure of polymers were investigated by 1H NMR, however the ratio of cis to trans of polymer couldn’t be obtained because the peak of H proton of cis and trans in carbon-carbon double bond didn’t divide. When the polymer obtained, the photophysical, electrochemical, and thermal properties of monomers and polymers were investigated. Fluorescence spectra of P1-P4 suggest their emission maxima located at 418,489,515 and 594nm, and which correspond to purblish blue, greenish blue, green, orange yellow color, respectively. However, the strong electron-withdrawing dicyanovinyl group didn’t extend the emission color to red region. The fluorescence quantum yield of P2 reaches to 0.42 and it is the highest one in four polymers and fluorescence quantum yield of other three polymers are round 0.02. The HOMO level of all polymers are close to -5.3 eV, which is close to the work fuction of ITO and indicates they all have good hole injection ability. The LUMO level of P4 is as low as to -3.02 eV. All polymers have high thermal stability and their decomposition temperature are higher than 400℃.Then, these donor-acceptor pendant were linked with 1,6-heptadiyne to obtained monomer A1, A2, and A3, then these monomers were polymerized through metathesis cyclopolymerization (MCP) to form polyacetylene deriatives PA1, PA2, and PA3, respectively. The MCP behavior of A1-A3 show strong solvent dependence and MCP of A1-A3 in tetrohydrofuran increased polymer yield obviously when compared with MCP in chloroform. The photophyscal property of monomers and polymers were investigated. A1, A2, and A3 emit blue, green, and red light, respectively, and the emission maxima of Al, A2, and A3 have a slightly red shift when compared with Ml, M2, and M4, respectively. PA1-PA3 have only weak fluorescence emission, which are very different with monomers. These weak emission are all attributed to the tricarbazole and polyacetylene main chain have no fluorescence emission in the visible light region. The HOMO level of PA1-PA3 are-5.04,-5.20, and -5.18 eV and the LUMO level of PA1, PA2, and PA3 are -3.17,-3.36, and -3.36 eV, respectively. Polyacetylene deriatives have higher and lower LUMO than polyolefin counterpart. Although these polyacetylene deriatives couldn’t be applied in OLED, they can absorb light in both ultraviolet region and visible region to fully utilize solar energy and possess more suitable energy level to facilitate the collection of holes and electron in the external circuit, these advantages make them can be used in organic solar cell. |
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