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Kuo C.-P.,Roosevelt Road | Chuang C.-N.,Institute of Polymer Science and Engineering | Chang C.-L.,Roosevelt Road | Leung M.-K.,Roosevelt Road | And 3 more authors.
Journal of Materials Chemistry C | Year: 2013

We report the study of the fluorescence switching properties of the conjugated copolymers containing triphenylamine, fluorene, benzo[2,1,3] thiadiazole, and cyclic urea moieties. The copolymers show excellent thermal stability and good solubility in polar organic solvents. While the electrofluorescent device (EFD) of P1 emits yellow light under UV excitation, fluorescence intensity is switched off upon electrochemical oxidation. In addition, the fluorescent behavior of the EFD of P1 can be reversibly switched between the non-fluorescent (oxidized) state and the fluorescent (neutral) state with a superb contrast ratio (If/If0) of 21.4. Furthermore, a white-light electrochemical fluorescence switching device is achieved by blending of P1 (yellow) with P2 (blue). Since the fluorescent conjugated polymers of P1 and P2 have their emission simultaneously quenched under the low working potential, the EFD could show a white-dark state of fluorescence with a high contrast ratio (If/If0) of 14.6. © 2013 The Royal Society of Chemistry. Source


Chuang C.-N.,Institute of Polymer Science and Engineering | Chang C.-Y.,Roosevelt Road | Chang C.-L.,Roosevelt Road | Wang Y.-X.,Roosevelt Road | And 3 more authors.
European Polymer Journal | Year: 2014

Hole-transporting photocurable blends of (4-(AcOCH2)C 6H4)3N (1) or ((4-(AcOCH2)C 6H4)2NC6H4)2 (2), poly(fluorene-co-triphenylamine)s (PFTs) and diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate (DIAS, a photoacid generator (PAG)) have been successfully formulated. Under UV irradiation (λ > 200 nm), PAG decomposes to release protons that catalyze the heterolytic decomposition of 1 and 2 to give benzylic cation intermediates. Friedel-Crafts type electrophilic aromatic substitution would then occur at the triphenylamine (TPA) units of PFT, leading to a photo-curing phenomenon. The curing efficiency is therefore highly dependent on the content of TPA in the PFT. This approach can be implemented to PLED applications. Under the optimized conditions, the polymeric light-emitting device of ITO/photo-cross-linkable HTL/PVK-Ir(ppy)3-t-PBD/Mg-Ag, with a turn-on voltage of 9.4 V (1 cd/m2), a maximum brightness of 7630 cd/m2, and a current efficiency of 15.8 cd/A was achieved. The lifetime of the device has also been improved by 1.8 times when compared with that of the STD device. © 2014 Elsevier Ltd. All rights reserved. Source

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