Construction of Carbon Dots@Alumina Materials with Long-Lived Room Temperature Phosphorescence for Digital Encryption

Abstract Room-temperature phosphorescence (RTP) carbon dots (CDs) materials have attracted considerable attention owing to their potential applications in digital encryption. However, achieving high-performance RTP CDs materials without introducing external emissive centers or complex substrates remains a significant challenge. Herein, CDs@Al2O3 materials were successfully prepared by a solid-state decomposition method with aluminum isopropoxide (AIP) as a single precursor. The double confinement of strong covalent bonds and a highly rigid structure is formed by calcination, which effectively suppresses the vibration of luminescent molecules and the non-radiative transition of triplet excitons and generates oxygen vacancies with suitable concentration (deeper traps) as effective trapping sites for triplet excitons. As a result, the CDs@Al2O3 material exhibits a long lifetime of 433.5 ms (more than 6 s to the naked eyes) and excellent stability. These composites show preliminary potential for applications in digital encryption. This work provides a simple strategy for the in situ construction of RTP CDs materials with a single precursor.