| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 100 === Novel conjugated polymers, PC and PT, containing electron-withdrawing trifluoromethyl group at 2 and 2’ positions of biphenyl moiety (CF3BP) and carbazole (CBZ) and triphenylamine (TPA) were synthesized by Horner-Emmons reaction. These polymers exhibited good thermal stability with glass transition temperatures ranging from 170 ℃ and 233 ℃, and 5 % decomposition temperatures higher than 400 ℃. The UV-visible absorption peaks were between 295 and 412 nm, and emission peaks were between 391 and 477 nm in solution states. Quantum efficiency(ΦPL) were between 39 and 88 %. Energy transfer phenomenon was observed in solution states of PC10 between CF3BP-CBZ-alternating segment and CF3BP-blocking segment, and PT10 between CF3BP- TPA -alternating segment and CF3BP-blocking segment. The cyclic voltammetric studies revealed that polymers had low HOMO (-5.27~-5.57 eV) and LUMO (-2.97~-3.17 eV) compared with carbazole- and triphenylamine-containing PPVs due to the presence of strong electron-withdrawing trifluoromethyl group. It was also observed the trifluoromethyl-substituted biphenyl (CF3BP) moiety was a stronger electron-withdrawing group than pyridine, 1,3,4-oxadiazole, 2,1,3-benzothiadiazole and cyano moieties. The PLED’s configuration is ITO/PEDOT:PSS/PC or PT/LiF/Ca/Al. In the conjugated polymers, PC, PC50 show the best performance. The turn-on voltage at 5.0 V, maximum luminance and maximum luminance efficiency are 696 cd/m2 and 1.45 cd/A, respectively. In the conjugated polymers, PT, PT50 show the best performance. The turn-on voltage at 3.8 V, maximum luminance and maximum luminance efficiency are 1003 cd/m2 and 2.95 cd/A, respectively. As the trifluoromethyl-substituted biphenyl (CF3BP) increased, the electron mobility enhanced. It indicted that the trifluoromethyl-substituted biphenyl (CF3BP) moiety can be a new candidate as the electron-withdrawing moiety to adjust the HOMO, LUMO energy levels and energy gaps of conjugated polymers.
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