Preparation and application of visible-light-responsive photochromic long-afterglow composites based on boron–carbon interfacial covalent bonds

Visible light is a more accessible and less phototoxic excitation light source in practical applications than ultraviolet light. However, it's still a challenge to prepare visible-light-excited carbon-dot long-afterglow photochromic materials. In this study, a carbon dots/boronic acid composite (CDs/BA) based on boron–carbon bond (B C) was synthesized. The CDs/BA under visible light excitation had a long-afterglow emission spectrum mixed of thermal activation delayed fluorescence (TADF) and room temperature phosphorescence (RTP), with an absolute photoluminescence quantum yield (PLQY) up to 30.35 %. After removed the visible light excitation source, the long afterglow lasted for more than 30 s. Moreover, the long afterglow emission of CDs/BA is excitation-dependent and time-dependent. On this basis, the anti-counterfeiting technology with more convenience (a mobile phone or flashlight can be used as a light source) and higher security was achieved.