A strongly greenish-blue-emitting Cu 4 Cl 4 cluster with an efficient spin–orbit coupling (SOC): fast phosphorescence versus thermally activated delayed fluorescence

In this communication, we report a new greenish-blue-emitting Cu(i) complex, Cu4Cl4(NP)2, a with high photoluminescence quantum yield of 90% and a short decay time of 9.9 μs. Due to the strong SOC combined with the small activation energy ΔEST, the emission at room temperature consists of approximately equivalent fast phosphorescence and TADF.