Theoretical investigations on the carbazole‐based conjugated polymers containing electron‐donating divinylaryl |
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Authors: | Liming Liu Xueye Wang Yanling Wang Xinyu Peng Yuexiang Mo |
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Institution: | College of Chemistry, Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Xiangtan, Hunan 411105, People's Republic of China |
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Abstract: | The polycarbazoles have been proved to efficiently suppress the keto defect emission. Three carbazole‐based conjugated polymers, poly9‐methyl‐3‐(4‐vinylstyryl)‐9H‐carbazole] (PBC), poly9‐methyl‐3‐(2‐(5‐vinylthiophen‐2‐yl)vinyl)‐9H‐carbazole] (PBT) and poly9‐methyl‐3‐(2‐(5‐vinylfuran‐2‐yl)vinyl)‐9H‐carbazole] (PBF), were investigated by quantum‐chemical techniques, and gain a detailed understanding of the influence of carbazole units and the introduction of electron‐donating on the electronic and optical properties. The electronic properties of the neutral molecules, HOMO‐LUMO gaps (ΔE), in addition to ionization potential (Ip) and electron affinity (Ea), are studied using B3LYP density functional theory. The lowest excitation energies (Eg) and the absorption wavelength are studied using the time dependent density functional theory (TDDFT). The calculated results show that all three series of polymers have good planarity. And the highest‐occupied molecular orbital (HOMO) energies lift about 0.36–0.61 eV and thus the IP decrease about 0.01–0.19 eV compared to polycarbazole, suggesting the significant improved hole‐accepting and transporting abilities. By introducing the electron‐donating 1,4‐divinylphenylene or 2,5‐divinylthiophene or 2,5‐divinylfuran units in the backbone, and the lowest‐unoccupied molecular orbital (LUMO) energies decrease 0.20–0.39 eV. In addition, PBC, PBT and PBF have longer maximal absorption wavelengths than polycarbazole. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 706–714, 2009 |
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Keywords: | luminescence molecular modeling polycarbazoles quantum chemistry time dependent density functional theory (TDDFT) |
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