Room temperature phosphorescent materials based on rosin acid with time-dependent afterglow and visible light excitation

Room-temperature phosphorescent (RTP) materials based on carbon dots (CDs) have received much attention due to their potential applications in anti-counterfeiting in recent years. However, it remains a considerable challenge to prepare CDs-based RTP materials with sunlight excitation and excellent stability. This work provides a straightforward method for one-step calcination of rosin-based carbon quantum dots (R-CDs) with aluminum hydroxide (Al(OH) 3 ) to create ecologically sustainable room-temperature phosphorescent materials (CDs@Al 2 O 3 ). CDs@Al 2 O 3 exhibit excitation dependence, emitting green phosphorescence under 365 nm excitation, yellow phosphorescence under visible light excitation, and blue-green phosphorescence under sunlight excitation. Surprisingly, CDs@Al 2 O 3 display time-dependent afterglow, switching from blue to green phosphorescence when excited at 285 nm. Furthermore, after being submerged in polar and acid-base solutions for 21 days, the phosphorescence of CDs@Al 2 O 3 is still visible to the unaided eye. At last, CDs@Al 2 O 3 composites are utilized in applications including smart flashing traffic signals, multi-level information, and anti-counterfeiting. This work expands creative application opportunities by offering a straightforward and adaptable approach to generating ecologically friendly RTP materials.