Bipolar gold(III) complexes for solution-processable organic light-emitting devices with a small efficiency roll-off.

A new class of bipolar alkynylgold(III) complexes containing triphenylamine and benzimidazole moieties has been synthesized, characterized, and applied as phosphorescent dopants in the fabrication of solution-processable organic light-emitting devices (OLEDs). The incorporation of methyl groups in the central phenyl unit has been found to rigidify the molecule to reduce nonradiative decay, yielding a high photoluminescence quantum yield of up to 75% in spin-coated thin films. In addition, the realization of highly efficient solution-processable OLEDs with an extremely small external quantum efficiency (EQE) roll-off has been demonstrated. At practical brightness level of 1000 cd m(-2), the optimized devices exhibited a high EQE of up to 10.0% and an extremely small roll-off of less than 1%.