Long-Range Charge Transport-Induced Color and Lifetime Tunable Afterglow Emission of Host–Guest Complexes

In a host–guest system, the traditional concept to achieve room temperature phosphorescence (RTP) is to stabilize the long-lived triplet state by the host matrix. The host reduces the non-radiative transition of guests and interaction with oxygen but seldom participates in excited state generation. In this work, the space through charge transfer (STCT) and long-range charge transport between α-cyclodextrin (α-CD) and diphenylacetylene (DPA) and its derivatives induce ultralong room temperature phosphorescence and thermally activated delayed fluorescence (TADF) emission. The charge transfer process plays an essential role in regulating the lifetime and color of afterglow emission. The tunable color and lifetime of afterglow emission could be realized by changing the guest's electronegativity. In addition, the host–guest complexes are readily fabricated by self-assembly. Inspired by multiple color and lifetime as well as the "switch" property of afterglow emission control by self-assembly and disassembly, the host–guest complexes exhibit potential application in rewritable ink, anti-counterfeiting, and information encryption.