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Convergent Modulation of Singlet and Triplet Excited States of Phosphine-Oxide Hosts through the Management of Molecular Structure and Functional-Group Linkages for Low-Voltage-Driven Electrophosphorescence

Authors

  • Chunmiao Han,

    1. Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
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    • These authors contributed equally to this work.

  • Zhensong Zhang,

    1. State Key Laboratory on Integrated Optoelectronics, College of Electronics Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (P. R. China)
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    • These authors contributed equally to this work.

  • Dr. Hui Xu,

    Corresponding author
    1. Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
    • Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
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  • Dr. Guohua Xie,

    1. State Key Laboratory on Integrated Optoelectronics, College of Electronics Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (P. R. China)
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  • Jing Li,

    1. Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
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  • Prof. Yi Zhao,

    Corresponding author
    1. State Key Laboratory on Integrated Optoelectronics, College of Electronics Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (P. R. China)
    • State Key Laboratory on Integrated Optoelectronics, College of Electronics Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (P. R. China)
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  • Dr. Zhaopeng Deng,

    1. Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
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  • Prof. Shiyong Liu,

    1. State Key Laboratory on Integrated Optoelectronics, College of Electronics Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (P. R. China)
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  • Prof. Pengfei Yan

    1. Key Laboratory of Functional Inorganic Material, Chemistry, Ministry of Education, Heilongjiang University, 74 Xuefu Road, Harbin 150080 (P. R. China), Fax: (+86) 451-86608042
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Abstract

The controllable tuning of the excited states in a series of phosphine-oxide hosts (DPExPOCzn) was realized through introducing carbazolyl and diphenylphosphine-oxide (DPPO) moieties to adjust the frontier molecular orbitals, molecular rigidity, and the location of the triplet excited states by suppressing the intramolecular interplay of the combined multi-insulating and meso linkage. On increasing the number of substituents, simultaneous lowering of the first singlet energy levels (S1) and raising of the first triplet energy levels (T1, about 3.0 eV) were achieved. The former change was mainly due to the contribution of the carbazolyl group to the HOMOs and the extended conjugation. The latter change was due to an enhanced molecular rigidity and the shift of the T1 states from the diphenylether group to the carbazolyl moieties. This kind of convergent modulation of excited states not only facilitates the exothermic energy transfer to the dopants in phosphorescent organic light-emitting diodes (PHOLEDs), but also realizes the fine-tuning of electrical properties to achieve the balanced carrier injection and transportation in the emitting layers. As the result, the favorable performance of blue-light-emitting PHOLEDs was demonstrated, including much-lower driving voltages of 2.6 V for onset and 3.0 V at 100 cd m−2, as well as a remarkably improved E.Q.E. of 12.6 %.

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