A novel furo[3, 2-c]pyridine-based iridium complex for high-performance organic light-emitting diodes with over 30% external quantum efficiency. Issue 39 (2nd October 2017) - Yan, Zhimin
Abstract : A novel furo[3, 2- c ]pyridine Ir complex has been developed by replacing S with O in the C^N ligand, which shows a blue-shifted emission and an EQE of over 30%. Abstract : A novel furo[3, 2- c ]pyridine based Ir complex, namely (pfupy)2 Ir(acac), has been developed by replacing sulfur with oxygen in the C^N ligand. Compared with the thiophene-containing (pthpy)2 Ir(acac), the LUMO level is elevated while the HOMO level remains almost unchanged for the resultant furan-containing (pfupy)2 Ir(acac). As a consequence, the emissive maximum is blue-shifted from 556 nm of (pthpy)2 Ir(acac) to 538 nm of (pfupy)2 Ir(acac) together with an improved photoluminescence quantum yield of 0.80. The corresponding device based on (pfupy)2 Ir(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.