Mechanoluminescent (ML) materials can directly convert external mechanical stimulation into lightwithout the need for excitation from other forms of energy, such as light or electricity. This alluring char-acteristic makes ML materials potentially applicable in a wide range of areas, including dynamic imaging

of force, advanced displays, information code, storage, and ani-counterfeiting encryption. However, cur-rent reproducible ML materials are restricted to sulfide- and oxide-based materials. In addition, most ofthe reported ML materials require pre-irradiation with ultraviolet (UV) lamps or other light sources,which seriously hinders their practical applications. Here, we report a novel ML material, MgF2:Mn2+,which emits bright red light under an external dynamic force without the need for pre-charging withUV light. The luminescence properties were systematically studied, and the piezophotonic applicationwas demonstrated. More interestingly, unlike the well-known zinc sulfide ML complexes reported previ-ously, a highly transparent ML film was successully fabricated by incorporating MgF2:Mn2+ into polydimethylsiloxane (PDMS) matrices. This film is expected to find applications in advanced flexibleoptoelectronics such as integrated piezophotonics, artificial skin, athletic analyt