Positively charged iridium(lll) triazole derivatives as blue emitters for light-emitting electrochemical cells

Cationic blue-emitting complexes with (2,4-difluoro)phenylpyridine and different 1,2,3-triazole ligands are synthesized with diffèrent 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.