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Phosphorescent materials offer a promising approach to information encryption due to their long luminescence lifetimes and high signal-to-noise ratios. However, fixed phosphorescent patterns are vulnerable to imitation over time, limiting their effectiveness in advanced encryption. Here, a time-division multiplexing physical unclonable function (TDM-PUF) label utilizing multicolor phosphorescent carbon dots (CDs) is proposed that leverages variations in wavelength and lifetime to construct time-resolved, multidimensional cryptographic protocols. Efficient multi-color phosphorescence in CDs is achieved by enhancing intersystem crossing, suppressing non-radiative transitions through confinement effects, and regulating emission spectra via energy transfer. The random spatial distribution and unpredictable emissions of phosphorescent CDs significantly enhance the complexity of the PUF system, thereby fortifying its defenses against mimicry attacks. Furthermore, this PUF system exhibits multiple optical responses over time, allowing correct information recognition only at specified time nodes, achieving time-resolved anti-counterfeiting. Finally, by segmenting PUF labels based on emission color and time channels, non-overlapping multicolor and multi-time segments are achieved, enabling highly secure time-division multiplexed encryption. The study provides a competitive anti-counterfeiting label and inspires the development of novel anti-counterfeiting strategies.
Li et al. (Sun,) studied this question.