Two platinum(ii) complexes with a 4-phenyl-4H-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: England Royal Society of Chemistry 07.02.2019
• Subjects: Coordination compounds; Crystallography; Current efficiency; Density distribution; Dichloromethane; Diodes; Efficiency; Ligands; Luminance distribution; Organic light emitting diodes; Phosphors; Photoluminescence; Platinum; Quantum efficiency; Triazoles
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt04750b

Two new cyclometalated platinum(ii) complexes ((TN T)Pt(dptp), (4tfmppy)Pt(dptp)) with 2',6'-bis(trifluoromethyl)-2,3'-bipyridine (TN T) and 4-trifluoromethylphenylpyridine (4tfmppy) as the cyclometalated ligands and the nitrogen heterocycle 2-(4,5-diphenyl-4H-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 = 532 nm, Φ = 65% for (TN T)Pt(dptp) and λ = 502 nm, Φ = 71% for (4tfmppy)Pt(dptp)) in CH Cl 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-4H-1,2,4-triazole group could facilitate charge trapping across the bulk of the device for efficient OLEDs.