Low-voltage, high-brightness and deep-red light-emitting electrochemical cells (LECs) based on new ruthenium(II) phenanthroimidazole complexes

Light-Emitting Electrochemical Cells (LECs) with a simple device structure ITO/Ru complex/Ga: In were prepared by using heteroleptic ruthenium(II) complexes containing 2-(2-hydroxyphenyl)-1(4-bromophenyl)-1h-imidazo[4,5-f][1,10] phenanthroline (hpbpip) as the pi-extended ligand. After ancillary ligand modification, the Ru(hpbpip)(dmbpy)(2)(2) complex shows a deep red electro-luminescence emission (2250 cd m(-2) at 6 V) centered at 685 nm, 65 nm red-shifted compared to the Ru(bpy)(3)(2) benchmark red-emitter at a very low turn voltage (2.6 V), demonstrating its potential for low-cost deep-red light sources. Moreover, the PL quantum yield of the Ru(hpbpip)(bpy)(2)(2) complex was revealed to be higher (0.121) than the benchmark standard Ru(bpy)(3) (0.095).