Dynamic Matrix Competition Enables Host‐to‐Guest Reversal for Tailoring Carbon Dots Afterglow From Time‐Dependent Color to White Emission

ABSTRACT Room‐temperature afterglow carbon dots (CDs) materials, combining long‐lived emission, low toxicity, structural tunability, and ease of processing, hold significant application prospects in information encryption, anti‐counterfeiting, lighting, and sensing. However, existing boric acid (BA)‐based CDs afterglow systems generally suffer from issues such as single‐color emission, limited stimulus‐response dimensions, and unclear matrix regulation mechanisms. Herein, a BA/NaOH dual‐matrix system was developed, in which CDs afterglow can be precisely regulated by matrix ratio, achieving orange‐to‐green and orange‐to‐cyan time‐dependent color‐changing afterglow, and white afterglow. Through structural characterization of the composites, it was found that with increasing NaOH content, the confinement environment transitioned from a BA‐dominated B‐O network to a NaOH‐dominated borate structure, Na ionic bonds, and a deprotonated CDs surface. The specific regulatory mechanism of NaOH on each emission center in the composites was elucidated as promoting the generation and enhancement of short‐wavelength thermally activated delayed fluorescence while suppressing long‐wavelength room‐temperature phosphorescence. Based on this, a theoretical model of “host‐to‐guest reversal” based on dynamic matrix competition was proposed. This work provides a new matrix competition regulation strategy for the design of single‐component multicolor and white CDs afterglow materials and demonstrates their application potential in multi‐level information encryption, anti‐counterfeiting patterns, Morse coding, and warning signage.