Tunable ultralong room-temperature phosphorescence from minoxidil-derived carbon-dot composites for multi-level information encryption

Abstract

Carbon dots (CDs), as an emerging class of carbon-based nanoluminophores, present a promising avenue for constructing efficient room-temperature phosphorescent (RTP) systems. To broaden the precursor library, ten different aminopyrimidine derivatives were selected as carbon sources in this work. Through a facile one-pot thermal treatment, a series of highly efficient RTP composite materials were successfully prepared. Among these, the product derived from minoxidil (MND), exhibited a photoluminescence quantum yield of 20.9% and an ultralong phosphorescence lifetime of 1.43 seconds. The phosphorescence emission color could be tuned from blue to green by adjusting the MND loading. Comprehensive characterization and theoretical calculations revealed the existence of dual emission centers within the material: one originating from nitrogen-doped CDs and the other from incompletely carbonized MND molecules. Benefiting from the dual tunability of both color and lifetime, the material was successfully applied in multi-level dynamic information encryption. This study confirms the feasibility of using aminopyrimidine derivatives as carbon sources for RTP materials, providing a new strategy for developing low-cost intelligent anti-counterfeiting materials.