Efficient Mechanoluminescent Elastomers for Dual‐Responsive Anticounterfeiting Device and Stretching/Strain Sensor with Multimode Sensibility

Abstract In this work, an environmentally friendly and novel oxide‐based mechanoluminescent material, Sr 3 Al 2 O 6 : Eu 3+ , which can serve as the alternative for the widely used but environmentally hazardous transition metal–doped sulfides is reported. This oxide could exhibit highly efficient photoluminescence, but even more efficient mechanoluminescence as embedded into polydimethylsiloxane matrix under mechanical stimulation. The emitting color of the resultant Sr 3 Al 2 O 6 : Eu 3+ /polydimethylsiloxane elastomer composites could be further manipulated by adjusting the synthesis atmosphere of the Sr 3 Al 2 O 6 : Eu 3+ based on its unique self‐reduction characteristic. Moreover, by combining the wavelength selectivity of photoluminescence and dynamic stress response of mechanoluminescence, Sr 3 Al 2 O 6 : Eu 3+ enables the design of two types of intriguing devices. They are a dual‐responsive anticounterfeiting flexible device activated by either photons or mechanics, and a comprehensive stretching/strain sensor capable of sensing both strain level and stretching states. In comparison to the conventional luminescent materials, with a rare combination of efficient photoluminescence, highly sensitive mechanoluminescence, and facile color tunability, Sr 3 Al 2 O 6 : Eu 3+ is much more versatile and ideal for various advanced applications.