Highly Repeatable and Cyclically Stable Mechanoluminescence of the Flexible Composite Elastomer

Mechanoluminescence (ML) elastomer shows tremendous potential for the next generation of flexible displaying, imaging, and sensing devices. However, inadequate repeatability and cyclic stability are the current bottlenecks. In this work, a solid-solution strategy is reported to regulate the interfacial interactions of ML elastomer, in which the (Ca,Ba)5(PO4)3Cl:Eu solid solutions and polydimethylsiloxane (PDMS) are employed, respectively. The results suggest that the solid-solution strategy can effectively modulate the energy position of the valence band and the charge density distributions of the lowest unoccupied band, as well as the interfacial triboelectrification. Consequently, the ML performance of the composite elastomer in terms of intensity, spectral characteristic, and repeatability has been significantly improved. Particularly, the optimum CaBa4(PO4)3Cl:Eu/PDMS elastomer exhibits stable and repeatable ML for over 20 000 cycles under various rapid and continuous stretching conditions. This work not only provides a highly repeatable and cyclically stable ML elastomer but also clarifies the intrinsic physical principles, showing high guiding significance for future ML design and applications.