High-color-rendering-index white polymer light-emitting electrochemical cells based on ionic host-guest systems: Utilization of blend films of blue-fluorescent cationic polyfluorenes and red-phosphorescent cationic iridium complexes

Yoshinori Nishikitani, Kotaro Suga, Soichi Uchida, Suzushi Nishimura, Kenichi Oyaizu, Hiroyuki Nishide

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

The authors present high-color-rendering-index (CRI) white polymer light-emitting electrochemical cells (PLECs) based on ionic host-guest systems. PLECs were fabricated with blend films composed of a blue fluorescent cationic π-conjugated polymer, poly(9,9-bis[6′-(N,N,N,-trimethylammonium)hexyl]fluorine-co-alt-1,4-phenylene)bromide (PFN+Br), used as a host, and a red phosphorescent cationic iridium complex, [Ir(ppy)2(biq)]+(PF6) (where (ppy) = 2-phenylpyridinate and biq = 2,2′-biquinoline), used as a guest. By optimizing the composition of PFN+Br and [Ir(ppy)2(biq)]+(PF6) in the active layers, white light emission with Commission Internationale de l'Eclairage (CIE) coordinates of (x = 0.28, y = 0.31) and a very high CRI of 95.8 was achieved through mixing of blue and red light at an applied voltage of 4.0 V. The white light emissions were obtained at a low [Ir(ppy)2(biq)]+(PF6) concentration (PFN+Br:[Ir(ppy)2(biq)]+(PF6) = 1:0.01 (mass ratio)), showing that [Ir(ppy)2(biq)]+(PF6) acts as a suitable energy acceptor. The emission mechanism of the ionic host-guest PLECs can be explained by Förster resonance energy transfer (FRET) and Dexter energy transfer (DET) from the excited PFN+Br to [Ir(ppy)2(biq)]+(PF6). Utilization of ionic host-guest PLECs is a very promising method for realizing white light-emitting devices with very high CRI.

Original languageEnglish
Pages (from-to)168-172
Number of pages5
JournalOrganic Electronics: physics, materials, applications
Volume51
DOIs
Publication statusPublished - 2017 Dec 1

Keywords

  • Energy transfer
  • High-color-rendering-index
  • Ionic host-guest systems
  • White polymer light-emitting electrochemical cells

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

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