Visible-Light-Excited Room-Temperature Afterglow from Carbonized Polymer Dots–Boron Oxide Nanohybrid for Data Encryption

Abstract The development of heavy metal-free room-temperature afterglow (RTA) materials is highly desirable, as it offers environmentally friendly, biocompatible platforms for diverse real-world applications. Herein, a color-tunable RTA material with a long lifetime of 1.72 s is achieved by embedding carbonized polymer dots (CPDs) within a boron oxide matrix. CPDs with abundant functionalities can strengthen the through-space conjugation (TSC) in thermally processed boric acid (BA) through various intermolecular interactions. Heated BA serves as a rigid matrix to confine the carbonized polymer dots, thereby suppressing nonradiative relaxation pathways. The photoexcited CPDs then act as sensitizers, populating the emissive levels of the host matrix via partial energy transfer. This TSC-assisted energy transfer and rigidification mechanism enables simultaneous modulation and enhancement of the optical properties of individual components within the nanohybrid. It is worth noting that the afterglow from the carbonized polymer dots–boron oxide nanohybrid can be observed by the naked eye at room temperature and lasts for several seconds (up to 14 s) when UV or visible-light excitation is turned off. In addition, this nanohybrid exhibits a notable afterglow efficiency of 4.92%. Endowed with favorable optical properties, this RTA material shows great potential for multifunctional applications, including data encryption and anticounterfeiting.