Incorporating High‐Dielectric‐Constant Modified PVDF Into Alternating Current Electroluminescent Fibers to Boost Brightness

ABSTRACT Alternating current electroluminescent (ACEL) fibers are regarded as a fundamental component essential for enabling display and interaction functionalities in next‐generation wearable technologies like electronic textiles. However, the practical applications of current ACEL fibers have long been limited by their relatively low luminous brightness, which typically remains below 200 cd/m 2 . Recognizing that the low dielectric constant of the commonly used polymer matrix in luminescent fibers largely limits their brightness, we developed a modified poly (vinylidene fluoride‐co‐chlorotrifluoroethylene) (M‐PVDF) with a high dielectric constant, which is fully compatible with the solution‐processing procedures and multilayer coaxial structure of ACEL fibers. It is not only easy to synthesize at a large scale but also exhibits excellent solution processability, high transparency (>90%), and good compatibility with ZnS particles, making it highly suitable for high‐performance ACEL fibers. The ACEL fiber based on M‐PVDF matrix achieves a remarkable brightness of 717 cd/m 2 at 110 V and 2 kHz, far surpassing that of conventional ACEL fibers. It also demonstrates outstanding stability and flexibility under harsh conditions, such as 80°C and −20°C for 7 days, 1 00 000 cycles of repeated friction, and a prolonged 80 h washing test. Furthermore, the 200‐meter‐long ACEL fibers produced at a large scale demonstrate high uniformity and stable luminance. These fibers could be woven into textiles for pattern display, showcasing their practical applicability across a wider range of illuminated environments.