Near-infrared stress memory emitters enable delayed impact visualization in illuminated environments.

Abstract

Rapid and accurate mechanical detection is essential across numerous fields. However, conventional camera-based methods, which depend on computationally intensive analysis of high-frame-rate footage and predictive algorithms, are often time-consuming and can introduce interpretive errors that compromise reliability. Herein, we present a class of near-infrared stress memory emitters, allowing fast and visualized mechanical detection in ambient environments. We develop Ca(Sr)ZnOS:Yb³⁺/Pb²⁺ crystals and achieve persistent mechanoluminescence at 981 nm by combinatorial engineering of sub-bandgap states. Deliberate modulation of the persistent mechanoluminescence intensity and duration is achieved through isostructural host blending coupled with prescribed ultraviolet charging, enabling direct capture and visualization of ball impacts with short processing time (0.39 s) and high accuracy. The bright (up to 11 × 10⁷ photons per event) and durable (up to 100 s) persistent mechanoluminescence broadens the scope of optical materials in applications such as stress sensors, human-machine interfaces, and mechano-opto-electronics.