High‐Contrast Fluorescent Electrophoretic Display Based on Upconversion Fluorescent Electrophoretic Particles for Multifunctional Dynamic Anticounterfeiting Applications

Abstract Fluorescence‐based anti‐counterfeiting (AC) technology, typically achieved through static printed images, is vulnerable to lower security and easier replication. Therefore, developing multifunctional and dynamic AC devices is crucial. The application of upconversion fluorescent materials to electrophoretic displays offers a promising approach to creating dynamic, multifunctional AC devices. In this work, a multifunctional AC device based on a fluorescent electrophoretic display (FEPD) is designed. By surface‐modifying commercial infrared fluorescent powder, an upconversion fluorescent electrophoretic particle (UCEP) is developed which can be driven under an electric field and emit green fluorescence under infrared light excitation. The UCEP is incorporated into black‐and‐white electrophoretic ink to fabricate the FEPD. This device exhibits a high ambient contrast ratio of 56, a fast response time of 175 ms, and the ability to switch from a white reflective state to a green luminous state under 980 nm light. These results demonstrate the potential application of the FEPD in dynamic, high‐security, and multifunctional AC devices.