Full-color room-temperature phosphorescent carbon dots with ultrahigh quantum yield via conjugation regulation

Room-temperature phosphorescent (RTP) materials have demonstrated significant application potential in various fields such as optoelectronic devices, information encryption, and bioimaging due to their superior optical properties. However, the realization of multicolor-tunable RTP materials with both long afterglow lifetime and high quantum yield simultaneously remains a great challenging. Herein, precursor molecules with various degrees of conjugation and different energy gaps were selected and combined with ammonium borate through a one-step pyrolysis method to successfully fabricate nitrogen doped carbon dots (N-CDs) based RTP materials with a long afterglow lifetime (880 ms) and ultrahigh phosphorescence quantum yield (81.13 %) simultaneously. As the conjugation degree of the precursors increases, the phosphorescent color tuning of the composites exhibits a satisfactory transition from blue to red. Leveraging these superior properties, the resultant N-CDs-based RTP materials have been applied to the fields of advanced information security and anti-counterfeiting. This work not only provides an important pathway for developing RTP materials with tunable color, but also proposes an engineering strategy for achieving tunable bandgaps in carbon materials.