Sustainable Lignocellulosic Room Temperature Phosphorescent Inks for Intelligent Packaging and Anti-Counterfeiting

Developing sustainable room-temperature phosphorescent (RTP) inks from abundant biomass resources is extremely attractive but remains a significant challenge in the field. Herein, the RTP lignocellulose was facilely prepared by simple immersion of lignocellulose powder in MgCl2 solutions. Compared to untreated lignocellulose, lignocellulose treated with 1 M MgCl2 exhibited a 10.7-fold increase in RTP intensity and a significantly prolonged RTP lifetime of 315.8 ms. The enhanced RTP performance of the treated lignocellulose is attributed to the synergistic effect of enhancing hydrogen bond interactions to suppress non-radiative transitions and narrowing the energy gap to accelerate the intersystem crossing (ISC) rate. Subsequently, the RTP lignocellulose was formulated into environmentally friendly water-based inks for screen printing using poly(vinyl alcohol) (PVA) as the binder, which was applied to the humidity-responsive smart labels in biscuit packaging and RTP anti-counterfeiting with time-resolved and multilevel information encryption. This research provides a new strategy for the development of sustainable RTP inks and prints.