Two platinum( ii ) complexes with a 4-phenyl-4 H -1,2,4-triazole derivative as an ancillary ligand for efficient green OLEDs

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 5; pp. 1892 - 1899
• Main Authors: Lu, Guang-Zhao, Tu, Zhen-Long, Liu, Liang, Zheng, You-Xuan, Zhao, Yue
• Format: Journal Article
• Language: English
• Published: 30.01.2019
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/C8DT04750B

Two new cyclometalated platinum( ii ) complexes ( (TN3T)Pt(dptp) , (4tfmppy)Pt(dptp) ) with 2′,6′-bis(trifluoromethyl)-2,3′-bipyridine (TN 3 T) and 4-trifluoromethylphenylpyridine (4tfmppy) as the cyclometalated ligands and the nitrogen heterocycle 2-(4,5-diphenyl-4 H -1,2,4-triazol-3-yl)phenol (dptp) as the ancillary ligand were developed. Both complexes are green phosphors with high photoluminescence quantum efficiency yields ( λ max = 532 nm, Φ p = 65% for (TN3T)Pt(dptp) and λ max = 502 nm, Φ p = 71% for (4tfmppy)Pt(dptp) ) in CH 2 Cl 2 solutions at room temperature, respectively. Organic light-emitting diodes (OLEDs) with single-emitting layer and double-emitting layer structures were fabricated with good performances. Particularly, the double-emitting layer device D2 based on the complex (4tfmppy)Pt(dptp) with 6 wt% doped concentration shows superior performances with a maximum EQE of 26.90% with mild efficiency roll-off. This study demonstrates that the ancillary ligand attached with a 4-phenyl-4 H -1,2,4-triazole group could facilitate charge trapping across the bulk of the device for efficient OLEDs.