Phenanthroimidazole as molecularly engineered switch for efficient and highly long-lived light-emitting electrochemical cell

Light-emitting electrochemical cells (LECs) based on Ir(III) complexes owing to the superior advantages exhibit high potential for display and lighting applications. Herein, a series of Ir(III) complexes based on phenanthroimidazole (PI) as an ancillary ligand were synthesized to achieve efficient and highly stable yellow-to-orange LEC devices with fast response. These complexes exhibit appropriate electrochemical stability and significant suppression of concentration quenching in the thin films compared to the archetype complex. The fabricated LECs showed remarkably long device lifetimes over 1400 and 2100 h and external quantum efficiency of 2 and 3% for yellow and orange-LECs, respectively. The obtained t1/2 for yellow LEC is much higher than archetype [Ir(ppy)2(phen)]+ and their phenanthroline-based analogues reported so far. The incorporation of an ionic tethered functional group on PI, improved the mobility of the emissive layer and reduced the device turn-on time by 75–88%. This study shows a facile functionalization and characterization of the PI ligand as well as its potential application in optoelectronic devices (OLED

Ruthenium phenanthroimidazole complexes for near infrared light-emitting electrochemical cells

By adding different electron donor moieties to the ancillary ligand in ruthenium(II) phenanthroimidazole complexes, we successfully designed near infrared light emitting complexes suitable for light emitting electro-chemical cells (LECs). By using a single-layer LEC architecture and incorporating a novel top contact via melted deposition, working devices were obtained without the addition of any hole or electron transport layer. The resulting devices exhibited a dramatic reduction in the turn-on voltage from 3.1 V to 2.3 V, which is the lowest value observed in the ruthenium phenanthroline family. With the substitution of suitable groups on the ancillary ligand, the electroluminescence wavelength was shifted from the red (617 nm) to the near Infrared (NIR) region (700 nm), with the highest efficacy of 0.45 cd A(-1) and external quantum efficiency (EQE) of 1.367%. These values are the highest for NIR-LECs based on ruthenium polypyridyl complexes reported so far

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)](ClO4)(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)](ClO4)(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)](ClO4)(2) complex was revealed to be higher (0.121) than the benchmark standard [Ru(bpy)(3)](2+) (0.095)