Long‐Persistent Circularly Polarized Luminescence from a Host‐Guest System Regulated by the Multiple Roles of a Gold(I)‐Carbene Motif.

The promotion of intersystem crossing (ISC) is critical for achieving a high‐efficiency long‐persistent luminescence (LPL) from organic materials. However, the use of a transition‐metal complex for LPL materials has not been explored because it can also shorten the emission lifetime by accelerating the phosphorescence decay. Here, we report a new class of LPL materials by doping a monovalent Au‐carbene complex into a boron‐embedded molecular host. The donor‐acceptor systems exhibit photoluminescence with both high efficiencies (>57 %) and long lifetimes (ca. 40 ms) at room temperature. It is revealed that the Au atom promotes the population of low‐lying triplet excited states of the host aggregate (T1*) which can be converted into the charge‐transfer (CT) state, thereby resulting in afterglow luminescence. Moreover, the use of a chirality unit on the guest molecule results in the LPL being circularly polarized. This work illustrates that transition‐metal complexes can be used for developing organic afterglow systems by exquisite control over the excited state mechanism. [ABSTRACT FROM AUTHOR]