Stress‐Triggered Mechanoluminescence in ZnO‐Based Heterojunction for Flexible and Stretchable Mechano‐Optics

Abstract Owing to the forthcoming global energy crisis, the search for energy‐saving materials has intensified. Over the past two decades, mechanically induced luminescent materials have received considerable attention as they can convert waste into useful components, for instance, the conversion from stress into light. However, this material features many constraints that limit its widespread application. Herein, a strategy to improve the mechanoluminescence (ML) of ZnO by embedding it in a ZnF 2 :Mn 2+ matrix is introduced. Upon dynamic excitation via an external stress, the reddish‐yellow ML is confirmed to originate from the 4 T 1 (4G) → 6 A 1 (6S) transition of the optically active Mn 2+ center. Moreover, the sample with the strongest ML contains the appropriate amount of ZnF 2 (ZnF 2 :ZnO = 7:3). By performing density functional theory calculations, a possible ML‐enhancement mechanism is elucidated, which indicates the formation of a ZnF 2 /ZnO:Mn 2+ heterojunction. Considering the unique characteristics of ML, its promising applications are demonstrated in various mechano‐optics scenarios, including flexible and stretchable optoelectronics, advanced self‐powered displays, e‐skins/e‐signatures, and anti‐counterfeiting, without the use of external light/electric‐incentive sources. The study significantly increases the variety of ML materials and is expected to strengthen the foundation for the future development of smart mechanically controlled devices and energy‐saving systems.