Time-Dependent Multicolor Afterglow from Dual Persistent Luminescence of Fluorescence and Phosphorescence in a UV-Cured Polyurethane Matrix

Abstract

It remains challenging to develop organic afterglow materials with a variable emission color and not a single color during decay. Herein, we developed a kind of time-dependent multicolor afterglow polyurethane (PU) system whose emission can undergo four distinct color changes within 1.0 s. The rapid UV-cured copolymerization of pyrene-1-carboxylate derivative (PyC) and poly(ε-caprolactone) (PCL) prepolymer ensured that the resulting PU systems possessed dual persistent luminescence of phosphorescence at 626 nm of a lifetime over 200 ms and delayed fluorescence (DF) at 393 nm of a lifetime up to 26 ms. Such a big separation of afterglow peaks (over 230 nm) is from the aggregated and the dispersed states of PyC and resulted in an afterglow color change from purple, via orange and yellow, to green. By virtue of such a colorful afterglow change, plus the rapid UV-cured preparation method, these materials have shown a promising application of time-dependent triple-level information encryption and anticounterfeiting.