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Zhao Z.,Hangzhou Normal University | Chan C.Y.K.,Hong Kong University of Science and Technology | Chen S.,Center for Display Research | Deng C.,Hong Kong University of Science and Technology | And 10 more authors.
Journal of Materials Chemistry | Year: 2012

Tetraphenylethene (TPE) is an archetypal luminogen that exhibits a phenomenon of aggregation-induced emission (AIE), while carbazole is a conventional chromophore which shows the opposite effect of aggregation-caused quenching (ACQ) of light emission in the condensed phase. Melding the two units at the molecular level generates a group of new luminescent materials that suffer no ACQ effect but depict high solid-state fluorescence quantum yields up to unity, demonstrative of the uniqueness of the approach to solve the ACQ problem of traditional luminophores. All the TPE-carbazole adducts are thermally and morphologically stable, showing high glass-transition temperatures (up to 179 °C) and thermal-degradation temperatures (up to 554 °C). Multilayer electroluminescence devices with configurations of ITO/NPB/emitter/TPBi/Alq 3/LiF/Al are constructed, which exhibit sky blue light in high luminance (up to 13650 cd m -2) and high current and external quantum efficiencies (up to 3.8 cd A -1, and 1.8%, respectively). The devices of the luminogens fabricated in the absence of NPB or hole-transporting layer show even higher efficiencies up to 6.3 cd A -1 and 2.3%, thanks to the good hole-transporting property of the carbazole unit. © 2012 The Royal Society of Chemistry.


Yuan W.Z.,Hong Kong University of Science and Technology | Yuan W.Z.,Shanghai JiaoTong University | Chen S.,Center for Display Research | Lam J.W.Y.,Hong Kong University of Science and Technology | And 8 more authors.
Chemical Communications | Year: 2011

Combination of an aggregation-induced emission (AIE) moiety and a dimesitylboron group yields a new three-coordinate boron compound exhibiting a synergistic effect: the resultant TPEDMesB shows AIE feature with solid-state emission efficiency up to unity and good electron-transport property, and thus remarkable electroluminescence (EL) performances. © 2011 The Royal Society of Chemistry.


Chan C.Y.K.,Hong Kong University of Science and Technology | Zhao Z.,Hong Kong University of Science and Technology | Lam J.W.Y.,Hong Kong University of Science and Technology | Liu J.,Hong Kong University of Science and Technology | And 11 more authors.
Advanced Functional Materials | Year: 2012

Benzene-cored luminogens with multiple triarylvinyl units are designed and synthesized. These propeller-shaped molecules are nonemissive when dissolved in good solvents, but become highly emissive when aggregated in poor solvents or in the solid state, showing the novel phenomenon of aggregation-induced emission. Restriction of intramolecular motion is identified as the main cause for this effect. Thanks to their high solid-state fluorescence quantum yields (up to unity) and high thermal and morphological stabilities, light-emitting diodes with the luminogens as emitters give sky-blue to greenish-blue light in high luminance and efficiencies of 10800 cd m -2, 5.8 cd A -1, and 2.7%, respectively. The emissions of the nanoaggregates of the luminogens can be quenched exponentially by picric acid, or selectively by Ru 3+, with quenching constants up to 10 5 and ∼2.0 × 10 5 L mol -1, respectively, making them highly sensitive (and selective) chemosensors for explosives and metal ions. Benzene-cored luminogens with multiple triarylvinyl units exhibit aggregation-induced emission. The high solid-state fluorescence quantum yields and high thermal and morphological stabilities of such emitters gave light-emitting diodes with sky-blue to greenish-blue light in high luminance and efficiencies. The emission could be quenched exponentially by picric acid, or selectively by Ru 3+, making them highly sensitive (and selective) chemosensors for explosives and metal ions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Liu Y.,Hong Kong University of Science and Technology | Liu Y.,Shandong University | Chen S.,Center for Display Research | Lam J.W.Y.,Hong Kong University of Science and Technology | And 4 more authors.
Journal of Materials Chemistry | Year: 2012

In organic light-emitting devices, materials with efficient electron-transporting properties, are essential. In this report, oxadiazole-containing tetraphenylethene TPE-Oxa is synthesized and its optical physics and electronic properties are investigated. The dye is almost nonluminescent when molecularly dissolved in solutions, but becomes highly emissive when aggregated in poor solvents or fabricated as thin films in the solid state. A quantum yield of unity has been achieved in its solid thin film. Inherited from the oxadiazole component, the dye molecule enjoys low-lying electronic band energies. Benefiting from the good electron-transporting and hole-blocking properties of the dye, the two-layer OLED devices using TPE-Oxa as both light-emitting and electron-transporting materials show superior performance, i.e., lower turn-on voltage, higher brightness and efficiencies, to the devices of typical configuration with a dedicated electron-transporting layer. © 2012 The Royal Society of Chemistry.


Yuan W.Z.,Hong Kong University of Science and Technology | Yuan W.Z.,Fok Ying Tung Research Institute | Lu P.,Hong Kong University of Science and Technology | Lu P.,Fok Ying Tung Research Institute | And 11 more authors.
Advanced Materials | Year: 2010

(Figure Presented) Efficient solid-state emitters developed by a new approach are described. While emission from triphenylamine (TPA) and its dimer (DTPA) is weakened by aggregation, attaching tetraphenylethene (TPE) units to the amines boosts their emission efficiencies up to 100% in the aggregate state. without harming their hole-transport properties. The resultant 3TPETPA and 4TPEDTPA luminogens show excellent electroluminescence performance. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

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