Issue 59, 2017, Issue in Progress

Photoluminescence and electroluminescence of deep red iridium(iii) complexes with 2,3-diphenylquinoxaline derivatives and 1,3,4-oxadiazole derivatives ligands

Abstract

Four iridium(III) complexes (Ir1 to Ir4) containing 2,3-diphenylquinoxaline derivatives with or without fluoro-substituted on different positions (L1: 2,3-diphenylquinoxaline; L2: 6,7-difluoro-2,3-diphenylquinoxaline; L3: 2,3-bis(4-fluorophenyl)quinoxaline; L4: 6,7-difluoro-2,3-bis(4-fluorophenyl)quinoxaline) as main ligands and 2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenol (HPOP) as ancillary ligand were synthesized and investigated. All the complexes emit deep red photoluminescence (PL) (Ir1: λmax: 645 nm; Ir2: λmax: 650 nm; Ir3: λmax: 634 nm; Ir4: λmax: 639 nm). Moreover, the electron mobility of the complexes Ir3 and Ir4 is higher than that of the electron transport material Alq3 (tris-(8-hydroxyquinoline)aluminium), which is beneficial for their performances in organic light-emitting diodes (OLEDs). The OLEDs with single- or double-emitting layers (EML) were fabricated using Ir3 or Ir4 as the emitter. The double-EML device using Ir4 with the structure of ITO (indium-tin-oxide)/MoO3 (molybdenum oxide, 5 nm)/TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane, 30 nm)/TcTa (4,4′,4′′-tris(carbazol-9-yl) triphenylamine): Ir4 (2 wt%, 10 nm)/26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine): Ir4 (2 wt%, 10 nm)/TmPyPB (1,3,5-tri(m-pyrid-3-yl-phenyl)benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displays good electroluminescence (EL) performances with maximum luminance, current efficiency, power efficiency and external quantum efficiency of up to 20 676 cd m−2, 14.0 cd A−1, 12.0 lm W−1 and 17.8%, respectively, and the efficiency roll-off ratio is mild. The results suggest that the number and position of fluoro-substituents can affect photophysical, electrochemical and electroluminescent properties of the Ir(III) complexes, which are potential deep red phosphorescent materials for specific OLED applications.

Graphical abstract: Photoluminescence and electroluminescence of deep red iridium(iii) complexes with 2,3-diphenylquinoxaline derivatives and 1,3,4-oxadiazole derivatives ligands

Supplementary files

Article information

Article type
Paper
Submitted
16 May 2017
Accepted
19 Jul 2017
First published
26 Jul 2017
This article is Open Access
Creative Commons BY license

RSC Adv., 2017,7, 37021-37031

Photoluminescence and electroluminescence of deep red iridium(III) complexes with 2,3-diphenylquinoxaline derivatives and 1,3,4-oxadiazole derivatives ligands

Y. Jing and Y. Zheng, RSC Adv., 2017, 7, 37021 DOI: 10.1039/C7RA05530G

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