Highly Efficiency Green Ir(III) Complexes with External Quantum Efficiency over 20% in Green Solvent Processed Phosphorescent Organic Light-Emitting Diodes
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Three new highly efficient green-emitting heteroleptic Ir(III) complexes based on naphthyridin-one core were designed and synthesized. The complex Ir1 consists of multifunctional 4-(2-ethoxyethoxy)picolinate as ancillary ligand whereas Ir2 and Ir3 have conventional ancillary ligand such as picolinate. Their photophysical, thermal and electrochemical properties were fully investigated. All the three complexes exhibited intense green emission in solution at room temperature. Interestingly, the Ir(III) complexes exhibited high PLQY over 70% in solution. The high-performance green-solvent processed PHOLEDs with Ir1 exhibits the maximum external quantum efficiency (EQEmax) of 23.60% and maximum current efficiency (CEmax) of 85.22 cd A-1 among this is highest reported CEs and EQE in green-solvent processed PHOLEDs. Additionally, the green PHOLEDs with Ir2 and Ir3 shows the EQEmax and CEmax of 21.54, 22.40% and 77.92, 81.63 cd A-1 at 1000 cd m-2, respectively.