Mononuclear Cu(I) halide complexes containing asymmetric diphosphine and diphenyl pyridyl monophosphine: Structures and photophysical properties

Thermally activated delayed fluorescent (TADF) Cu(I) halide complexes have attracted attention due to their highly emission and short lifetimes (several mu s scale). Here, three mononuclear four-coordinate Cu(I) halide complexes containing asymmetric diphosphine and pyridyl phosphine, [CuX(L1)(L2)] (L1 = 2,3-bis(diphenylphoshino)thiophene, L2 = 2-(diphenylphosphino)pyridine, X = I (1), Br(2), Cl (3)), were synthesized and their structures and photophysical properties were characterized. At room temperature, complexes 1-3 in powder exhibit intense green to yellow green delayed fluorescence (lambda(em) = 497-523 nm, tau = 1.5-4.3 mu s, phi = 0.19-0.28). The emissions of the complexes 1-3 are originated from (metal + halide)-to-ligand and intra-ligand charge transfer. More contributions from MLCT and XLCT can result in the shorter decay lifetimes (1.6 similar to 4.3 mu s), which will prevent a roll-off of efficiency with increasing current density in OLED devices.

Automated summary

Thermally activated delayed fluorescent (TADF) Cu(I) halide complexes with short lifetimes and intense emissions were synthesized and characterized. These complexes exhibit intense green to yellow-green delayed fluorescence and are suitable for OLED devices.