A versatile color tuning strategy for iridium(III) and platinum(II) electrophosphors by shifting the charge-transfer states with an electron-deficient core

Gui Jiang Zhou, Qi Wang, Wai Yeung Wong, Dongge Ma, Lixiang Wang, Zhenyang Lin

Research output: Journal article publicationJournal articleAcademic researchpeer-review

74 Citations (Scopus)

Abstract

By fusing an electron-deficient ring system with the phenyl ring of a 2-phenylpyridine (ppy)-type ligand, a new and synthetically versatile strategy for the phosphorescence color tuning of cyclometalated iridium(III) and platinum(II) metallophosphors has been established. Two robust red electrophosphors with enhanced electron-injection/electron-transporting features were prepared by using an electron-trapping fluoren-9-one chromophore in the ligand design. The thermal, photophysical, redox and electrophosphorescent properties of these complexes are reported. These exciting results can be attributed to a switch of the metal-to-ligand charge-transfer (MLCT) character of the transition from the pyridyl groups in the traditional IrIIIor PtIIppy-type complexes to the electron-deficient ring core, and the spectral assignments corroborate well with the electrochemical data as well as the time-dependent density functional theory (TD-DFT) calculations. The electron-withdrawing character of the fused ring results in much more stable MLCT states, inducing a substantial red-shift of the triplet emission energy from yellow to red for the IrIIIcomplex and even green to red for the PtIIcounterpart. Electrophosphorescent organic light-emitting devices (OLEDs) doped with these red emitters fabricated by using vacuum evaporation technique have been realized with reasonable performance.
Original languageEnglish
Pages (from-to)1872-1883
Number of pages12
JournalJournal of Materials Chemistry
Volume19
Issue number13
DOIs
Publication statusPublished - 24 Mar 2009
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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