Regulating the Aggregation and Dispersion of Carbon Dots to Achieve Stimulus-Responsive Multimodal Luminescence for Dynamic Anti-Counterfeiting

Abstract

Stimulus-responsive multimodal luminescence (MML) within a single material system is highly desirable for anti-counterfeiting and information encryption applications. However, achieving adjustable MML within a unified material framework is challenging due to the distinct responses of different luminescence modes to a common external stimulus. In the work, a novel approach is devised for regulating the aggregation or dispersion state of carbon dots (CDs) to exhibit responsive MML, including fluorescence (FL), room temperature phosphorescence (RTP), and chemiluminescence (CL). Specifically, aggregation-caused luminescence quenching CDs (ACQCDs) are synthesized via a one-step hydrothermal method using levofloxacin. These ACQCDs exhibit ACQ and significant aggregation-induced color change effects. When ACQCDs interact with paper-based materials, they form hydrogen bonds, establishing a high-density hydrogen bond network that induces ACQCDs aggregation. Upon external stimulation, the hydrogen bond network undergoes dynamic changes, triggering ACQCDs dispersion. This process effectively deactivates nonradiative defect centers, stabilizes triplet excitons, and promotes simultaneous MML of tunable FL, RTP, and CL. The integration of multimodal luminescence with external stimulus input enables the creation of a programmable multi-input logic gate, offering significant potential for encoded information anti-counterfeiting applications. Overall, this research provides valuable insights into the conduction of MML CDs, thereby advancing the utilization of nanomaterials in intelligent encryption and anti-counterfeiting technologies. The findings pave the way for the development of more sophisticated and secure anti-counterfeiting measures based on the unique luminescent properties of CDs.