Dual-mode thermochromic afterglow in phosphorus-doped carbon dot composites for visible light-activated information encryption
Xin Bao, Xiaodong Zhu, Zhen Tian, Hui Wang, Hui Li, Xi Yuan
Abstract
The phenomena of thermochromic afterglow have attracted significant attention in advanced information encryption and anticounterfeiting applications. However, it is still a challenge to realize visible light-activated thermochromic afterglow in a single material. Herein, we demonstrate thermochromic afterglow under visible light excitation in a novel carbon dot (CD)-based composite, utilizing a temperature-dependent dual-mode afterglow mechanism. The composite (PCD@BA) is synthesized by incorporating phosphorus-doped CDs (PCDs) into an inorganic rigid matrix via covalent bonding. Notably, phosphorus doping significantly enhances the photoluminescent properties and redshifts the excitation wavelength of the PCD@BA composite, enabling it to exhibit bright thermally activated delayed fluorescence (TADF) when activated by white light. The thermochromic afterglow of the PCD@BA composite exhibits dynamic color transitions from deep blue to orange by tuning the proportion of the temperature-dependent room temperature phosphorescence (RTP) and TADF. Consequently, the concepts of white light-excited high-resolution multilevel afterglow 2D code information encryption and thermochromic afterglow based anticounterfeiting labels were developed. This work offers exciting opportunities for utilizing CD-based materials with visible light-activated thermochromic afterglow in advanced information security fields.