Efficient Light-Emitting Electrochemical Cells (LECs) Based on Ionic Iridium(III) Complexes with 1,3,4-Oxadiazole Ligands

Authors

  • Jing Zhang,

    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Li Zhou,

    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Hameed A. Al-Attar,

    1. Department of Physics, Durham University, Durham, DH1 3LE, UK
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  • Kuizhan Shao,

    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Li Wang,

    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Dongxia Zhu,

    Corresponding author
    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
    • Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Zhongmin Su,

    Corresponding author
    1. Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
    • Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin 130024 P. R. China
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  • Martin R. Bryce,

    Corresponding author
    1. Department of Chemistry, Durham University, Durham, DH1 3LE, UK
    • Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
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  • Andrew P. Monkman

    1. Department of Physics, Durham University, Durham, DH1 3LE, UK
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Abstract

Eight new iridium(III) complexes 1-8, with 1,3,4-oxadiazole (OXD) derivatives as the cyclometalated C^N ligand and/or the ancillary N^N ligands are synthesized and their electrochemical, photophysical, and solid-state light-emitting electrochemical cell (LEC) properties are investigated. Complexes 1, 2, 7 and 8 are additionally characterized by single crystal X-ray diffraction. LECs based on complexes 1-8 are fabricated with a structure indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/cationic iridium complex:ionic liquid/Al. LECs of complexes 16 with OXD derivatives as the cyclometalated ligands and as the ancillary ligand show yellow luminescence (λmax = 552–564 nm). LECs of complexes 7 and 8 with cyclometalated C^N phenylpyridine ligands and an ancillary N^N OXD ligand show red emission (λmax 616–624 nm). Using complex 7 external quantum efficiency (EQE) values of >10% are obtained for devices (210 nm emission layer) at 3.5 V. For thinner devices (70 nm) high brightness is achieved: red emission for 7 (8528 cd m−2 at 10 V) and yellow emission for 1 (3125 cd m−2 at 14 V).

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