A cationic iridium complex with tetrafluoroborate (BF4 (-)) as anion was synthesized and characterized for its potential application in display and solid state lighting devices. Light-emitting electrochemical cells (LECs) based on this complex displayed yellow electroluminescence with CIE coordinates of (0.50, 0.49). The imidazolium ionic liquids such as BMIMBF4 and EMIMBF4 were separately added to the light-emitting layer of the devices and their effects on the electroluminescent properties were studied. The presence of smaller BF4 (-) ion effectively facilitates the charge injection from the electrodes and hence results in rapid increase of luminance and current density of the devices with voltages.