Positively Charged Iridium(III) Triazole Derivatives as Blue Emitters for Light-Emitting Electrochemical Cells

• Published in: Advanced functional materials Vol. 20; no. 11; pp. 1812 - 1820
• Main Authors: Mydlak, Mathias, Bizzarri, Claudia, Hartmann, David, Sarfert, Wiebke, Schmid, Günter, De Cola, Luisa
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 09-06-2010; WILEY‐VCH Verlag
• Subjects: Cationic; cationic complexes; Crystal structure; Derivatives; Electrochemical cells; electroluminescence; Emission spectroscopy; Excitation; iridium; Ligands; triazole; Triazoles
• ISSN: 1616-301X; 1616-3028; 1616-3028
• DOI: 10.1002/adfm.201000223

Cationic blue‐emitting complexes with (2,4‐difluoro)phenylpyridine and different 1,2,3‐triazole ligands are synthesized with different counterions. The influence of the substituents on the triazole ligand is investigated as well as the influence of the counterions. The substituents do not change the emission energy but, in some cases, slightly modify the excited‐state lifetimes and the emission quantum yields. The excited‐state lifetimes, in apolar solvents, are slightly dependent on the nature of the counterion. A crystal structure of one of the compounds confirms the geometry and symmetry postulated on the basis of the other spectroscopic data. Light‐emitting electrochemical cell devices are prepared and the recorded emission is the bluest with the fastest response time ever reported for iridium complexes.
A series of blue‐emitting cationic iridium(III) complexes are prepared and investigated. They are employed in electroluminescent devices in combination with ionic liquids, showing the bluest emission and the shortest turn‐on time ever reported for iridium complexes.