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Issue 42, 2016
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Efficient deep-blue OLEDs based on phenanthro[9,10-d]imidazole-containing emitters with AIE and bipolar transporting properties

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Abstract

Highly efficient deep-blue emitters, especially those matching the NTSC (National Television Standards Committee) blue standard CIE (Commission Internationale de L’Eclairage) coordinate of (0.14, 0.08), are crucial for full-colour displays and white lighting. However, deep-blue emitters with excellent electroluminescence performance are rare. According to the strategy of developing highly luminescent solids by constructing aggregation-induced emission (AIE) systems, two AIE-type blue emitters, mTPE-PPI and mTPE-DPI, have been synthesized by integrating a triphenylethylene (TPE) group with one or two phenanthro[9,10-d]imidazole (PI) groups. The adoption of the PI unit with a large optical bandgap, the meta-linkage of the PI and the TPE units on a benzene ring, and the twisted molecular conformations of present AIE systems endow these compounds with bright blue emission in the solid state. In addition, these compounds are capable of transporting both electrons and holes and possess appropriate HOMO and LUMO levels for carrier injections. These features enable them to serve as excellent blue-emitting materials in OLEDs. A non-doped OLED based on mTPE-PPI displayed deep-blue light with the CIE coordinate of (0.15, 0.09) and a maximum external quantum efficiency (EQEmax) of 2.30%. An analogous device with mTPE-DPI as the emitting layer emitted blue light (CIE: 0.15, 0.14) with a high EQEmax of 3.69% and low efficiency roll-off. Further improvement of device performance has been achieved by the doping technique. The doped device of mTPE-DPI was able to realize deep-blue emission (CIE: 0.15, 0.10) matching well the blue standard, meanwhile reaching a EQEmax of 5.52% that represents the highest value reported for deep-blue OLEDs based on AIE compounds.

Graphical abstract: Efficient deep-blue OLEDs based on phenanthro[9,10-d]imidazole-containing emitters with AIE and bipolar transporting properties

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Publication details

The article was received on 09 Sep 2016, accepted on 05 Oct 2016 and first published on 05 Oct 2016


Article type: Paper
DOI: 10.1039/C6TC03923E
Citation: J. Mater. Chem. C, 2016,4, 10120-10129
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    Efficient deep-blue OLEDs based on phenanthro[9,10-d]imidazole-containing emitters with AIE and bipolar transporting properties

    C. Li, J. Wei, J. Han, Z. Li, X. Song, Z. Zhang, J. Zhang and Y. Wang, J. Mater. Chem. C, 2016, 4, 10120
    DOI: 10.1039/C6TC03923E

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