Rare‐Earth Coordination Hydrogels Enabling Self‐Powered and Self‐Luminous Closed‐Loop Systems

. By directly coupling RE-doped fluorescent hydrogels with RE-TENGs, we demonstrate, for the first time, a fully self-powered and self-luminous hydrogel platform. The integrated device efficiently charges capacitors and drives UV LEDs to reveal encrypted fluorescent patterns without any external power supply. This work establishes a new paradigm for merging energy harvesting with information display, opening opportunities for next-generation wearable and secure optoelectronics.