Chinese Journal of Applied Chemistry ›› 2020, Vol. 37 ›› Issue (1): 16-23.DOI: 10.11944/j.issn.1000-0518.2020.01.190150

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White Phosphorescent Star-Shape Polymers Derived from Poly(fluorene-carbazole) with Green-Yellow Iridium Complex as the Cores

ZENG Huijuan,LIN Meijuan(),LIU Chao,CHEN Longjie,ZHANG Yushan,LING Qidan   

  1. College of Chemistry and Materials,Fujian Normal University/Fujian KeyLaboratory of Polymer Materials,Fuzhou 350007,China
  • Received:2019-05-23 Accepted:2019-08-26 Published:2020-01-08 Online:2020-01-08
  • Contact: LIN Meijuan
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21374017), and the Natural Science Foundation of Fujian Province(No.2017J01683)

Abstract:

An efficient green-yellow light iridium complex based on 2-(4-brominephenyl)-1-octyl-benzimidazole as cyclometalated ligand and 3-bromine-5-(pyridin-2-yl)-1H-1,2,4-triazole as ancillary ligand was synthesized. A series of novel star-shape phosphorescent polymers (P2.5, P5.0 and P10) was synthesized by employing the iridium complex as the core guest and the poly(fluorine-carbazole) as the arm host through Suzuki cross-coupling. The properties of the iridium complex and polymers were studied. The results showed that the iridium complex emitted green-yellow light with peaks at 490,526 and 565 nm and its fluorescent quantum efficiency was 32.06%. Fluorescent lifetimes for the iridium complex and the polymers are in the microsecond regime (1.093.93 s). Such long-lived excited states clearly suggest that the emitting state has triplet phosphorescent emission. The yellow light intensity was enhanced with the increasing of iridium complex content, indicating that there exists partial energy transfer from host to guest, and the emission color of polymers shifts from blue to yellow by adjusting the proportion of the iridium complex. When the mole fraction of iridium complex reached to 2.5%, the white-light polymer (P2.5) was obtained, the CIE1931 chromaticity coordinate was (0.30, 0.32), the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels were 5.49 and 2.43 eV respectively, fluorescent quantum efficiency was 14.3%, and fluorescent lifetime was 2.22 s. The polymer having good thermal stability can satisfy the requirements of luminescent materials.

Key words: poly(fluorine-carbazole), iridium complex, star-shape polymer, photoluminescence, white-light emission