Efficient Time‐dependent Dual‐Model Room Temperature Phosphorescent Carbon Quantum Dots/ Boron Nitride Carbide Oxide Matrices

Abstract Room temperature phosphorescence (RTP) materials have broad applications in the field of optical devices due to tunable wavelengths and lifetimes. However, creating efficient RTP materials that possess multiple optical properties remains a challenge. Herein, a novel approach is developed to in situ form carbon quantum dots (C‐dots) embedded in boron nitride carbide oxide (B‐N‐C‐O) matrices by introducing nitrogen, phosphorus, and boron dopants into C‐dots (P/B/N doped C‐dots), enabling dual RTP emissions and time‐dependent afterglow. P/B/N doped C‐dots are synthesized by a vacuum‐assisted gradient heating approach using ethylenediamine, phosphoric acid, and boric acid as precursors with a yield of 20 g per batch. The introduction of P/B/N dopants provided multiple triplet states, which enable the C‐dots to have dual RTP emissions and, a long phosphorescent lifetime ranging from 0.98 to 1.30 s. The in situ formation of matrices surrounding the C‐dots enables ultrahigh quantum yield of up to 50%, surpassing the most recently reported RTP C‐dots. To demonstrate the potential applications of the RTP C‐dots, they are used as anti‐counterfeiting ink and phosphorescent dyes for security codes and phosphorescent polyester yarn, showing their suitability for high‐level security applications. This work provides an effective route for large‐scale synthesis of highly efficient RTP materials and preparation of high‐performance optical devices.