Hai-Ching SuHsiao-Fan ChenCHUNG-CHIH WUKEN-TSUNG WONG2018-09-102018-09-102008-1118614728http://scholars.lib.ntu.edu.tw/handle/123456789/342721https://www.scopus.com/inward/record.uri?eid=2-s2.0-55449121642&doi=10.1002%2fasia.200800020&partnerID=40&md5=2715ee27816993fad74004b993adf090We 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. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.Electrochemical cells; Electroluminescence; Ionic liquids; Iridium; Light-emitting devicesjournal article10.1002/asia.2008000202-s2.0-55449121642WOS:000261002000005