Effect of ionic liquids on the electroluminescence of yellowish-green light-emitting electrochemical cells using bis(2-(2,4-difluorophenyl)pyridine)4,7-diphenyl-1,10-phenanthroline-iridium(III) hexafluorophosphate

A cationic iridium complex [Ir(dfppy)2(dpphen)]PF6, where dfppy is 2-(2,4-difluorophenyl)pyridine, dpphen is 4,7-diphenyl-1,10-phenanthroline and PF6− is hexafluorophosphate, has been synthesized and its photophysical and electrochemical properties were investigated. Light-emitting electrochemical cells (LECs) based on this complex were fabricated using air stable electrodes and emits yellowish-green light (533 nm) with Commission Internationale de L’Eclairage (CIE) coordinates of (0.35, 0.59) at 4 V. Effect of two different imidazolium based ionic liquids (ILs) viz, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) and 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIMPF6) on the active layer has been studied and the luminance and the current density of the devices were found to be enhanced with increasing ionic conductivities.