Unprecedented Homoleptic Bis-Tridentate Iridium(III) Phosphors : Facile, Scaled-Up Production, and Superior Chemical Stability

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

27 Scopus Citations
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Author(s)

  • Jun Lin
  • Yang Wang
  • Premkumar Gnanasekaran
  • Yu-Cheng Chiang
  • Chun-Chieh Yang
  • Chih-Hao Chang
  • Shih-Hung Liu
  • Gene-Hsiang Lee
  • Pi-Tai Chou
  • Shun-Wei Liu

Detail(s)

Original languageEnglish
Article number1702856
Journal / PublicationAdvanced Functional Materials
Volume27
Issue number35
Online published26 Jul 2017
Publication statusPublished - 20 Sep 2017
Externally publishedYes

Abstract

Bis-tridentate Ir(III) metal complexes are expected to show great potential in organic light-emitting diode (OLED) applications due to the anticipated, superb chemical and photochemical stability. Unfortunately, their exploitation has long been hampered by lack of adequate methodology and with inferior synthetic yields. This hurdle can be overcome by design of the first homoleptic, bis-tridentate Ir(III) complex [Ir(pzpyph)(pzHpyph)] (1), for which the abbreviation (pzpyph)H (or pzHpyph) stands for the parent 2-pyrazolyl-6-phenyl pyridine chelate. After that, methylation and double methylation of 1 afford the charge-neutral Ir(III) complex [Ir(pzpyph)(pzMepyph)] (2) and cationic complex [Ir(pzMepyph)2][PF6] (3), while deprotonation of 1 gives formation of anionic [Ir(pzpyph)2][NBu4] (4), all in high yields. These bis-tridentate Ir(III) complexes 2–4 are highly emitted in solution and solid states, while the charge-neutral 2 and corresponding t-butyl substituted derivative [Ir(pzpyBuph)(pzMepyBuph)] (5) exhibit superior photostability versus the tris-bidentate references [Ir(ppy)2(acac)] and [Ir(ppy)3] in toluene under argon, making them ideal OLED emitters. For the track record, phosphor 5 gives very small efficiency roll-off and excellent overall efficiencies of 20.7%, 66.8 cd A−1, and 52.8 lm W−1 at high brightness of 1000 cd m−2. These results are expected to inspire further studies on the bis-tridentate Ir(III) complexes, which are judged to be more stable than their tris-bidentate counterparts from the entropic point of view.

Research Area(s)

  • bis-tridentate, cyclometalates, iridium, organic light-emitting diodes, phosphorescence

Citation Format(s)

Unprecedented Homoleptic Bis-Tridentate Iridium(III) Phosphors : Facile, Scaled-Up Production, and Superior Chemical Stability. / Lin, Jun; Wang, Yang; Gnanasekaran, Premkumar; Chiang, Yu-Cheng; Yang, Chun-Chieh; Chang, Chih-Hao; Liu, Shih-Hung; Lee, Gene-Hsiang; Chou, Pi-Tai; Chi, Yun; Liu, Shun-Wei.

In: Advanced Functional Materials, Vol. 27, No. 35, 1702856, 20.09.2017.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal