| 초록 |
Two new heteroleptic blue emitting Ir(III) complexes, EtOCN-FIracac and tBuCN-FIracac, and a homoleptic Ir(III) complex, tBu-FCNIr, consisting of 2′,4″-difluorophenylpyridine (dfppy) with CN group at 5′-position of the phenyl and EtO- or tBu group at 4-position of the pyridine as main ligand are synthesized and characterized for PhOLEDs. The dual functionalization of dfppy core with the electron withdrawing CN and electron donating EtO- or tBu- groups leads to improved blue color purity by compensating the bathochromic shift originating from the ancillary ligand of the heteroleptic Ir(III) complexes. The PhOLEDs based on tBuCN-FIracac and EtOCN-FIracac show one of the highest efficiencies ever achieved for blue color with a maximum EQE of 22.3% (39.2 cd A-1) and 21.5% (35.1 cd A-1), respectively with a simple device structure; while the similar device based on tBu-FCNIr display a maximum EQE of 16.2% (23.5 cd A-1). |
