Construction of efficient solid emitters with conventional and AIE luminogens for blue organic light-emitting diodes

• DOI: 10.1039/c1jm10221d
• Publication Date: 2011-06-22T10:42:33Z
• Authors: Zujin Zhao; Shuming Chen; Chunmei Deng; Jacky W. Y. Lam; Carrie Y. K. Chan; Ping Lu; Zhiming Wang; Bingbing Hu; Xiaopeng Chen; Ping Lu; Hoi Sing Kwok; Yuguang Ma; Huayu Qiu; Ben Zhong Tang
• Keywords: Triphenylamine; Carbazole; Quantum Efficiency

9,9-Bis(9-heptyl-3-carbazolyl)fluorenes (BPyBCF, BAnBCF, BTPABCF, and BTPEBCF, where B = Bis, Py pyrene, C carbazole, F fluorene, An anthracene, TPA triphenylamine, TPE tetraphenylethene) with different chromophoric units at the 2,7-positions are synthesized in moderate to high yields (52–89%) by Suzuki coupling reactions of 9,9-bis(9-heptyl-3-carbazolyl)-2,7-dibromofluorene corresponding arylboronic acid utilized as active layers for construction blue organic light-emitting diodes (OLEDs). BPyBCF, BAnBCF BTPABCF emit intense light fluorescence quantum (ΦF 75–94%) solution. However, they exhibit much lower ΦF values (30–61%) film state, revealing that aggregate formation has quenched their emission. On contrary, BTPEBCF is weakly emissive solution 0.3%) but becomes a strong emitter 100%) when fabricated into solid film, demonstrating phenomenon aggregation-induced emission (AIE). Restriction intramolecular rotation suppression intermolecular interactions due propeller-like tetraphenylethene unit responsible AIE phenomenon. All luminogens thermally morphologically stable, showing glass-transition (Tg 109–147 °C) thermal-degradation temperatures (Td 396–478 °C). Non-doped OLEDs using constructed, which give electroluminescence maximum current (ηC,max) external (ηext,max) efficiencies 4.8 cd A−1 2.3%. With same device configuration, shows higher ηC,max ηext,max 7.9 2.9%, respectively, thanks its feature.