The design and construction of organic afterglow materialsis anattractive but formidably challenging task due to the low intersystemcrossing efficiency and nonradiative decay. Here, we developed a hostsurface-induced strategy to achieve excitation wavelength-dependent(Ex-De) afterglow emission through a facile dropping process. Theprepared PCz@dimethyl terephthalate (DTT)@paper system exhibits aroom-temperature phosphorescence afterglow, with the lifetime up to1077.1 +/- 15 ms and duration time exceeding 6 s under ambientconditions. Furthermore, we can switch the afterglow emission on andoff by adjusting the excitation wavelength below or above 300 nm,showing a remarkable Ex-De behavior. Spectral analysis demonstratedthat the afterglow originates from the phosphorescence of PCz@DTTassemblies. The stepwise preparation process and detailed experiments(XRD, H-1 NMR, and FT-IR analysis) proved the presence ofstrong intermolecular interactions between the carbonyl groups onthe surface of DTT and the entire frame of PCz, which can inhibitthe nonradiative processes of PCz to achieve afterglow emission. Theoreticalcalculations further manifested that DTT geometry alteration underdifferent excitation beams is the main reason for the Ex-De afterglow.This work discloses an effective strategy for constructing smart Ex-Deafterglow systems that can be fully exploited in a range of fields.
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