Thermally Activated Delayed Fluorescence from d<sup>10</sup>‐Metal Carbene Complexes through Intermolecular Charge Transfer and Multicolor Emission with a Monomer–Dimer Equilibrium
Lei Cao, Shiqing Huang, Wei Liu, Hongyan Zhao, Xiao‐Gen Xiong, Jianping Zhang, Li‐Min Fu, Xiaoyu Yan
Abstract
Abstract A series of two‐coordinate Au I and Cu I complexes ( 3 a , 3 b and 5 a , 5 b ) are reported as new organometallic thermally activated delayed fluorescence (TADF) emitters, which are based on the carbene–metal–carbazole model with a pyridine‐fused 1,2,3‐triazolylidene (PyTz) ligand. PyTz features low steric hindrance and a low‐energy LUMO (LUMO=−1.47 eV) located over the π* orbitals of the whole ligand, which facilitates intermolecular charge transfer between a donor (carbazole) and an accepter (PyTz). These compounds exhibit efficient TADF with microsecond lifetimes. Temperature‐dependent photoluminescence kinetics of 3 a supports a rather small energy gap between S 1 and T 1 (Δ E =60 meV). Further experiments reveal that there are dual‐emission properties from a monomer–dimer equilibrium in solution, exhibiting single‐component multicolor emission from blue to orange, including white‐light emission.