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Blue Phosphorescent Iridium Complexes with Fluorine‐free Main Ligands for Efficient Organic Light‐emitting Diodes
Author(s) -
Shin Hwa Yong,
Jeong Seongjin,
Kim Sung Hyun,
Hong JongIn
Publication year - 2017
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.11177
Subject(s) - oled , iridium , phosphorescence , picolinic acid , fluorine , dopant , photochemistry , pyridine , chemistry , ring (chemistry) , phosphorescent organic light emitting diode , ligand (biochemistry) , pyrimidine , quantum efficiency , materials science , medicinal chemistry , stereochemistry , optoelectronics , fluorescence , organic chemistry , doping , biochemistry , physics , receptor , layer (electronics) , quantum mechanics , catalysis
Two heteroleptic iridium( III ) complexes with fluorine‐free pyridylpyrimidine main ligands were designed and synthesized for use as blue phosphorescent emitters in organic light‐emitting diodes ( OLEDs ). Complexes 1 and 2 have a molecular formula of Ir(C ∧ N) 2 (L ∧ X), where C ∧ N = 2‐tert‐butyl‐5‐(pyridin‐2‐yl)pyrimidine ( b5ppmH ) is the main ligand and L ∧ X = picolinic acid (pic) and 2‐( 1H ‐tetrazol‐5‐yl)pyridine (ptz) are ancillary ligands. The thermal, photophysical, and electrochemical properties of these complexes were investigated. Even without electron‐withdrawing fluorine substituents, the complexes emitted blue light at 463 and 455 nm with moderate quantum efficiencies (Φ PL = 0.54 and 0.43), respectively. Furthermore, the replacement of the pyridine ring with a pyrimidine ring allowed blue emission without fluorine substituents. An organic light‐emitting device fabricated using complex 2 as a dopant and 1,3‐bis(N‐carbazolyl)benzene ( mCP ) as a host exhibited a maximum external quantum efficiency of 11.5% and color coordinates of (0.17, 0.26) at 100 cd/m 2 .