Synthesis, crystal structure and photophysical properties of two TADF ionic cuprous complexes bearing 1,2,3-triazole ligand

Herein two novel ionic cuprous complexes [Cu(POP)(Pytzb)]BF4 (Cu1, POP = bis(2-diphenylphosphinophenyl) ether, Pytzb = 2-(1-(benzyl)-1H-1,2,3-triazol-4-yl)pyridine) and [Cu(Xantphos)(Pytzb)]BF4 (Cu2, Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) have been synthesized in reasonable yields, and their crystal structure, UV absorption and photoluminescent properties, as well as electrochemical behaviors were investigated. At 300 K, both Cu1 and Cu2 in solid state exhibit outstanding green luminescence peaked at 533 and 526 nm, respectively, with significantly high photoluminescent quantum yields (PLQYs, 47.5 and 60.5%, respectively). Detailed exploration of emission decay times for Cu1 and Cu2 in dependence of temperature demonstrates that the two complexes are typical thermally activated delayed fluorescence (TADF) materials at ambient temperature with TADF proportions of 83 and 80%, respectively. The two complexes were employed as dopants in solution-processed electroluminescent devices.