A novel furo[3,2-c]pyridine-based iridium complex for high-performance organic light-emitting diodes with over 30% external quantum efficiency

Abstract

A novel furo[3,2-c]pyridine based Ir complex, namely (pfupy)₂Ir(acac), has been developed by replacing sulfur with oxygen in the C^N ligand. Compared with the thiophene-containing (pthpy)₂Ir(acac), the LUMO level is elevated while the HOMO level remains almost unchanged for the resultant furan-containing (pfupy)₂Ir(acac). As a consequence, the emissive maximum is blue-shifted from 556 nm of (pthpy)₂Ir(acac) to 538 nm of (pfupy)₂Ir(acac) together with an improved photoluminescence quantum yield of 0.80. The corresponding device based on (pfupy)₂Ir(acac) realizes a record-high external quantum efficiency (EQE) of 30.5% (110.5 cd A⁻¹) without any out-coupling technology. Even at a luminance of 1000 and 5000 cd m⁻², the EQE still remains at 26.6% (96.4 cd A⁻¹) and 25.6% (92.7 cd A⁻¹), respectively, indicative of the gentle efficiency roll-off. The results clearly demonstrate the great potential of furan-based functional materials applied in OLEDs.