A Flexible Polymer with Reversible Mechano‐Responsive Ultralong Organic Phosphorescence for Trace Collision Detection

Ultralong organic phosphorescence (UOP) materials are garnering significant attention for their potential in advanced optoelectronics. Despite recent progress, achieving reversible mechano‐responsive UOP remains a formidable challenge, particularly for materials capable of dynamic afterglow color tuning. Herein, we propose an effective strategy to dynamically tune UOP by modulating intermolecular energy transfer via precise mechanical control. Under mechanical stimuli, the resulting composite polymer films exhibit a distinct ratiometric transition in delayed emission, characterized by an intensity decrease at 500/534 nm with a concurrent enhancement at 600 nm. Notably, this long‐lived luminescence demonstrates a more pronounced response to mechanical deformation than prompt fluorescence, demonstrating an intrinsic superiority of time‐gated signaling in eliminating background interference. Furthermore, the polymer displays exceptional reversibility and durability, recovering its initial state either spontaneously under ambient conditions or at an accelerated rate via thermal treatment. This unique ratiometric mechano‐responsivity facilitates high‐contrast, high‐fidelity applications in impact sensing and occlusal force mapping. This work provides a universal platform for engineering smart UOP materials and expands the applications of phosphorescent polymers in advanced sensing technologies.