A multi-responsive pattern switchable PDLC anti-counterfeiting platform with instant IR/UV readout enabled via upconversion–fluorophore synergy and electrode addressing

Abstract

Infrared-responsive anti-counterfeiting based on polymer dispersed liquid crystals (PDLCs) remains insufficiently explored. Existing PDLC infrared-responsive strategies usually rely on spatially fixed photothermal absorbers, which restrict switching of encrypted information, limit coding complexity, and introduce readout delays due to thermal inertia. Here, a PDLC platform doped with upconversion particles and fluorescent dyes that supports information switching with immediate responses under infrared (IR) and ultraviolet (UV) illumination is reported. Invisible light responsiveness was achieved and the contrast ratio of the PDLCs increased to 137.06 by tuning the content of the fluorinated monomer TFEMA together with the dopant loading. Integration with laser etched electrodes yielded a multi-responsive device combining UV/IR/alternating-current control. Electric field enabled switching among multiple pattern states, while irradiation at 365 and 980 nm modulated the multistate color output. The electrical and optical driven channels remained independent and orthogonal, which markedly expanded the encoding capacity. The device eliminates reliance on IR absorbers and heat accumulation, establishing a general route to low-latency, high-complexity encryption and enabling rapid, switchable, secure anti-counterfeiting authentication.