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

Abstract

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)-4 H-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.