Self-powered mechanoluminescent elastomer for solar-blind ultraviolet emission

Flexible mechanoluminescence (ML) elastomers show significant potential for next-generation wearable electronics, artificial skin, advanced sensing, and human-machine interaction. However, their broader application has been hindered by challenges such as restricted emission wavelengths, inadequate repeatability, insufficient cyclic stability, and poor self-recovery. Here, we report an innovative and high-performance solar-blind ultraviolet ML elastomer by combining commercial polydimethylsiloxane (PDMS) and newly fabricated Sr₃(BO₃)₂:Pr³⁺ phosphors, capable of generating intense ultraviolet-C (UVC) ML peaked at 272 nm under mechanical stimulation. The composite elastomer exhibits exceptional repeatability and cyclic stability, maintaining detectable UVC emission over 10,000 continuous stretching cycles (power intensity at the 1st cycle is ~6.2 mW m^-2). It also demonstrates rapid and efficient self-recovery behavior, restoring 43.2% of its initial intensity within 1 s and 90.2% after 24 h. Combined experimental and theoretical analyses reveal that interfacial triboelectrification, involving electron transfer from the phosphor to the PDMS matrix, leads to the observed UVC ML emission. Leveraging the solar-blind nature and high photon energy of UVC light, we further demonstrate the feasibility of self-powered photonics applications. This work not only offers novel insights into the design of advanced UVC ML systems but also provides "power-free" solutions for important applications where UVC photons are essential, such as outdoor optical tagging and microbial sterilization.