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Efficient Light‐Emitting Electrochemical Cells (LECs) Based on Ionic Iridium(III) Complexes with 1,3,4‐Oxadiazole Ligands
Author(s) -
Zhang Jing,
Zhou Li,
AlAttar Hameed A.,
Shao Kuizhan,
Wang Li,
Zhu Dongxia,
Su Zhongmin,
Bryce Martin R.,
Monkman Andrew P.
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201300344
Subject(s) - iridium , ligand (biochemistry) , materials science , electrochemistry , cationic polymerization , pedot:pss , indium tin oxide , oxadiazole , luminescence , electroluminescence , ionic bonding , phosphorescence , electrochemical cell , photochemistry , crystallography , fluorescence , polymer chemistry , chemistry , nanotechnology , ion , optoelectronics , layer (electronics) , organic chemistry , electrode , optics , biochemistry , receptor , physics , catalysis
Abstract Eight new iridium(III) complexes 1‐8 , with 1,3,4‐oxadiazole (OXD) derivatives as the cyclometalated C^N ligand and/or the ancillary N^N ligands are synthesized and their electrochemical, photophysical, and solid‐state light‐emitting electrochemical cell (LEC) properties are investigated. Complexes 1 , 2 , 7 and 8 are additionally characterized by single crystal X‐ray diffraction. LECs based on complexes 1‐8 are fabricated with a structure indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/cationic iridium complex:ionic liquid/Al. LECs of complexes 1 – 6 with OXD derivatives as the cyclometalated ligands and as the ancillary ligand show yellow luminescence (λ max = 552–564 nm). LECs of complexes 7 and 8 with cyclometalated C^N phenylpyridine ligands and an ancillary N^N OXD ligand show red emission (λ max 616–624 nm). Using complex 7 external quantum efficiency (EQE) values of >10% are obtained for devices (210 nm emission layer) at 3.5 V. For thinner devices (70 nm) high brightness is achieved: red emission for 7 (8528 cd m −2 at 10 V) and yellow emission for 1 (3125 cd m −2 at 14 V).