Decreased turn-on times of single-component light-emitting electrochemical cells by tethering an ionic iridium complex with imidazolium moieties

Hai-Ching Su; Hsiao Fan Chen; Chung Chih Wu; Ken Tsung Wong

doi:10.1002/asia.200800020

Decreased turn-on times of single-component light-emitting electrochemical cells by tethering an ionic iridium complex with imidazolium moieties

Hai-Ching Su, Hsiao Fan Chen, Chung Chih Wu^*, Ken Tsung Wong

^*Corresponding author for this work

Institute of Lighting and Energy Photonics

Research output: Contribution to journal › Article › peer-review

53 Scopus citations

Abstract

We report a significant decrease in turn-on times of light-emitting electrochemical cells (LECs) by tethering imidazolium moieties onto a cationic Ir complex. The introduction of two imidazolium groups at the ends of the two alkyl side chains of [Ir(ppy)₂(dC6-daf)]⁺(PF ₆)^- (ppy=2-phenylpyridine, dC6-daf=9,9′-dihexyl-4,5- diazafluorene) gave the complex [Ir(ppy)₂(dC6MIM-daf)] ³⁺[(PF₆)^-]₃ (dC6MIM-daf=9,9-bis[6- (3-methylimidazolium) hexyl]-1-yl-4,5-diazafluorene). Both complexes exhibited similar photoluminescent/electrochemical properties and comparable electroluminescent efficiencies. The turn-on times ofthe LECs based on the latter complex, however, were much lower than those of devices based on the former. The improvement is ascribed to increased concentrations of mobile counterions ((PF₆)^-) in the neat films and a consequent increase in neat-film ionic conductivity. These results demonstrate that the technique is useful for molecular modifications of ionic transition-metal complexes (ITMCs) to improve the turn-on times of LECs and to realize single-component ITMC LECs compatible with simple driving schemes.

Original language	English
Pages (from-to)	1922-1928
Number of pages	7
Journal	Chemistry - An Asian Journal
Volume	3
Issue number	11
DOIs	https://doi.org/10.1002/asia.200800020
State	Published - 13 Nov 2008

Keywords

Electrochemical cells
Electroluminescence
Ionic liquids
Iridium
Light-emitting devices

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title = "Decreased turn-on times of single-component light-emitting electrochemical cells by tethering an ionic iridium complex with imidazolium moieties",

abstract = "We report a significant decrease in turn-on times of light-emitting electrochemical cells (LECs) by tethering imidazolium moieties onto a cationic Ir complex. The introduction of two imidazolium groups at the ends of the two alkyl side chains of [Ir(ppy)2(dC6-daf)]+(PF 6)- (ppy=2-phenylpyridine, dC6-daf=9,9′-dihexyl-4,5- diazafluorene) gave the complex [Ir(ppy)2(dC6MIM-daf)] 3+[(PF6)-]3 (dC6MIM-daf=9,9-bis[6- (3-methylimidazolium) hexyl]-1-yl-4,5-diazafluorene). Both complexes exhibited similar photoluminescent/electrochemical properties and comparable electroluminescent efficiencies. The turn-on times ofthe LECs based on the latter complex, however, were much lower than those of devices based on the former. The improvement is ascribed to increased concentrations of mobile counterions ((PF6)-) in the neat films and a consequent increase in neat-film ionic conductivity. These results demonstrate that the technique is useful for molecular modifications of ionic transition-metal complexes (ITMCs) to improve the turn-on times of LECs and to realize single-component ITMC LECs compatible with simple driving schemes.",

keywords = "Electrochemical cells, Electroluminescence, Ionic liquids, Iridium, Light-emitting devices",

author = "Hai-Ching Su and Chen, {Hsiao Fan} and Wu, {Chung Chih} and Wong, {Ken Tsung}",

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AU - Su, Hai-Ching

AU - Chen, Hsiao Fan

AU - Wu, Chung Chih

AU - Wong, Ken Tsung

PY - 2008/11/13

Y1 - 2008/11/13

N2 - We report a significant decrease in turn-on times of light-emitting electrochemical cells (LECs) by tethering imidazolium moieties onto a cationic Ir complex. The introduction of two imidazolium groups at the ends of the two alkyl side chains of [Ir(ppy)2(dC6-daf)]+(PF 6)- (ppy=2-phenylpyridine, dC6-daf=9,9′-dihexyl-4,5- diazafluorene) gave the complex [Ir(ppy)2(dC6MIM-daf)] 3+[(PF6)-]3 (dC6MIM-daf=9,9-bis[6- (3-methylimidazolium) hexyl]-1-yl-4,5-diazafluorene). Both complexes exhibited similar photoluminescent/electrochemical properties and comparable electroluminescent efficiencies. The turn-on times ofthe LECs based on the latter complex, however, were much lower than those of devices based on the former. The improvement is ascribed to increased concentrations of mobile counterions ((PF6)-) in the neat films and a consequent increase in neat-film ionic conductivity. These results demonstrate that the technique is useful for molecular modifications of ionic transition-metal complexes (ITMCs) to improve the turn-on times of LECs and to realize single-component ITMC LECs compatible with simple driving schemes.

AB - We report a significant decrease in turn-on times of light-emitting electrochemical cells (LECs) by tethering imidazolium moieties onto a cationic Ir complex. The introduction of two imidazolium groups at the ends of the two alkyl side chains of [Ir(ppy)2(dC6-daf)]+(PF 6)- (ppy=2-phenylpyridine, dC6-daf=9,9′-dihexyl-4,5- diazafluorene) gave the complex [Ir(ppy)2(dC6MIM-daf)] 3+[(PF6)-]3 (dC6MIM-daf=9,9-bis[6- (3-methylimidazolium) hexyl]-1-yl-4,5-diazafluorene). Both complexes exhibited similar photoluminescent/electrochemical properties and comparable electroluminescent efficiencies. The turn-on times ofthe LECs based on the latter complex, however, were much lower than those of devices based on the former. The improvement is ascribed to increased concentrations of mobile counterions ((PF6)-) in the neat films and a consequent increase in neat-film ionic conductivity. These results demonstrate that the technique is useful for molecular modifications of ionic transition-metal complexes (ITMCs) to improve the turn-on times of LECs and to realize single-component ITMC LECs compatible with simple driving schemes.

KW - Electrochemical cells

KW - Electroluminescence

KW - Ionic liquids

KW - Iridium

KW - Light-emitting devices

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JO - Chemistry - An Asian Journal

JF - Chemistry - An Asian Journal

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ER -

Decreased turn-on times of single-component light-emitting electrochemical cells by tethering an ionic iridium complex with imidazolium moieties

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