A binuclear aluminum(III) complex: Thermal stability, photophysical, electrochemical and electroluminescent properties

A novel binuclear aluminum(III) complex with acylpyrazolone derivative as ligands, bis(salicylidene-o-aminophenol)-bis(4-benzoyl-3-methyl- 1-phenyl-2-pyrazolin-5-one)-bis-aluminum(III) [Al-2(saph)(2)(PMBP)(2)] was designed and synthesized. A detailed study was carried out on its thermal stability, photophysical, electrochemical and electroluminescent properties. It was found that the introduction of 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (PMBP) ligands improved the thermal stability remarkably. Organic light-emitting diodes (OLEDs) based on this Al complex as the sole emitter and the host for red dopant were fabricated. Bright green-yellow emission was observed from the device using Al-2(saph)(2)(PMBP)2 as the emitter and the electron transporting layer. Pure red emission peaked at 632 nm was obtained from the Al-2(saph)(2)(PMBP)(2) doped with DCJTB [4-(dicyanomethylene)-2-tertbutyl-6(1,1,7,7,-tetramethyljulolidyl-9-enyl)-4H-pyran] device with a luminance efficiency of 1.51 cd/A at 200 A/m(2). No light from Al-2(saph)(2)(PMBP)(2) was found, indicating that the matched energy levels provide an efficient red emission system in Al-2(saph)(2)(PMBP)(2) device. Those results demonstrated that Al-2(saph)(2)(PMBP)(2) might be a promising material for OLEDs. (C) 2007 Elsevier B.V. All rights reserved.