Electroluminescent properties of yellow light-emitting electrochemical cells based on a cationic iridium complex and the effect of ionic liquids incorporation in an active layer

Abstract A cationic iridium complex [Ir(ppz)2(dmphen)]PF6 was synthesized, in which ppz is 1-phenylpyrazole and dmphen is 5,6-dimethyl-1,10-phenanthroline, and characterized by spectroscopic and photophysical methods. Light-emitting electrochemical cells (LECs) were fabricated using the resulting complex and their electroluminescent properties were investigated. LECs based on [Ir(ppz)2(dmphen)]PF6 gave a yellow electroluminescence of 4052 cd m− 2 at 9.0 V. Furthermore, the luminance of the devices was constructively tuned by doping ionic liquids (ILs) into the light emitting layer. The addition of ILs resulted in enhanced luminance of the devices at shorter turn-on voltages indicating its great potential for display and lighting applications. Among the three employed ILs, BMIMPF6 showed best performance in terms of luminance of 3850 cd m− 2 at 6.5 V.