TADF and X-ray Radioluminescence of New Cu(I) Halide Complexes: Different Halide Effects on These Processes.

A series of complexes [CuX(PicPO)] (X = Cl, Br, I) based on tris(pyridin-2-ylmethyl)phosphine oxide (PicPO) has been synthesized. At 298 K, these compounds exhibit thermally activated delayed fluorescence (TADF) of (M+X)LCT type with λ varying from 485 to 545 nm, and quantum efficiency up to 54%. In the TADF process, the halide effect appears as the emission intensification and bathochromic shift of λ in the following order X = I < Br < Cl.