Blue fluorophores comprised of tetraphenylethene and imidazole: aggregation-induced emission and electroluminescence

Abstract

By melting tetraphenylethene (TPE) and 1,2,4,5-tetraphenyl-1H-imidazole (TPI) units together through different linking positions, three new fluorophores are synthesized, and their optical, electronic and electroluminescence (EL) properties are fully studied. Owing to the presence of TPE unit(s), these fluorophores are weak emitters in solutions, but are induced to emit strongly in the aggregated state, presenting typical aggregation-induced emission characteristics. The experimental and computational results reveal that different connection patterns between TPE and TPI could impact the molecular conjugation greatly, leading to varied emission wavelength, fluorescence quantum yield and EL performance in organic light emitting diodes (OLEDs). The fluorophore built by attaching TPE unit to the 1-position of imidazole ring shows bluest fluorescence, and its EL device emits at deep blue region (445 nm; CIE= (0.16, 0.15)). And the device based on the fluorophore by linking TPE to the 2-position of imidazole ring shows EL at 467 nm (CIE= (0.17, 0.22)) with good efficiencies of 3.17 cd·A^-1, and 1.77%.

Keywords

aggregation-induced emission (AIE) / tetraphenylethene (TPE) / imidazole / blue fluorescence / organic light emitting diode (OLED)

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Acknowledgements

We acknowledge the financial support from the National Natural Science Foundation of China (Grant Nos. 51273053, 21404029 and 21274034), the Guangdong Innovative Research Team Program of China (No. 201101C0105067115) and the National Basic Research Program of China (973 Program) (No. 2013CB834702).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg