Multi-Stimuli-Responsive Carbon Dots with Intrinsic Photochromism and In Situ Radical Afterglow

The combination of advanced photoluminescence characteristics to photochromism is highly attractive in preparing high-performance multifunctional photo-responsive materials for optoelectronic applications. However, this is rather challenging in material design owing to the limited mechanism understanding and construction principles. Here, an effective strategy to integrate photochromism and afterglow emission in carbon dots (CDs) is proposed through embedding naphthaleneimide (NI) structure in CDs followed by polyvinylpyrrolidone (PVP) encapsulation. The NI-structured CDs-PVP shows intrinsic photochromism owing to the in situ formation of NI-radical anions and controllable multi-stimuli-responsive afterglow behaviors related to the oxygen-trigged triplet exciton quenching and Förster resonance energy transfer (FRET) from the pristine CDs to the photoactivated CDs radicals. Notably, a wide range of appearance colors from colorless to brown, luminescence color transition from blue to yellow, and much elongated afterglow lifetime up to 253 ms are observed. With the extraordinary stimuli-chromic and stimuli-luminescent CDs-PVP film dynamically responsive to multiple external stimuli, reversible secure snapchat, data encryption/decryption and synaptic imaging recognition are realized. These findings demonstrate a fundamental principle to design multi-stimuli-responsive photochromic CDs with afterglow, providing important understandings on the synergic mechanism of dynamic photochromism and emission behaviors and thereby expanding their applications in advanced information anti-counterfeiting and artificial intelligence.