Ambipolar D-A type bifunctional materials with hybridized local and charge-transfer excited state for high performance electroluminescence with EQE of 7.20% and CIEy ∼ 0.06

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Bin Liu
  • Zi-Wei Yu
  • Dan He
  • Ji Zheng
  • Ya-Dong Yu
  • Wen-Fa Xie
  • Qing-Xiao Tong

Detail(s)

Original languageEnglish
Pages (from-to)5402-5410
Journal / PublicationJournal of Materials Chemistry C
Volume5
Issue number22
Online published9 May 2017
Publication statusPublished - 2017

Abstract

Construction of donor–acceptor (D–A) molecules with a highly hybridized local and charge-transfer (HLCT) excited state has been shown to be an effective strategy to achieve the maximum electroluminescence (EL) efficiency through the synchronous harvest of high photoluminescence (PL) efficiency and exciton utilization. Herein, two novel D–A-structured bifunctional (emissive and hole-transporting) materials, PPI-2TPA and PPI-2NPA, have been designed and synthesized for application in deep-blue OLEDs. As revealed by theoretical calculations and comprehensive photophysical experiments, both of them exhibit significant HLCT excited-state characteristics and ambipolar properties. Using them as emitting layers (EML) in multilayer non-doped devices presents true deep-blue Commission Internationale de l’Eclairage (CIE) coordinates of ca. (0.15, 0.06), accompanied by record-setting performance with maximum external quantum efficiencies (EQEs) of 7.20% for PPI-2TPA and 6.33% for PPI-2NPA. Remarkably, the simple bilayer devices fabricated using them as non-dopant EML and hole-transporting layers (HTLs) still deliver EQEs as high as 4.69% and 4.10% with little changes in color purity (PPI-2TPA: CIE (0.150, 0.063) and PPI-2NPA: (0.152, 0.063)). To the best of our knowledge, this performance is the highest among the reported non-doped devices in this color gamut, irrespective of whether the two newly formed molecules functioned as EML or EML and HTL simultaneously.

Citation Format(s)

Ambipolar D-A type bifunctional materials with hybridized local and charge-transfer excited state for high performance electroluminescence with EQE of 7.20% and CIEy ∼ 0.06. / Liu, Bin; Yu, Zi-Wei; He, Dan et al.
In: Journal of Materials Chemistry C, Vol. 5, No. 22, 2017, p. 5402-5410.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review