Flexible PVDF/SAOED Composite Film for Triboelectric Energy Harvesting and Long Persistent Luminescence toward Self-Powered Smart Roads

Achieving both efficient mechanical energy harvesting and all-night passive luminescence in a single flexible film remains a critical challenge for self-powered smart road systems. In this work, a poly(vinylidene fluoride)/SrAl2O4:Eu2+,Dy3+ (PVDF/SAOED) composite film is fabricated by tape-casting, which integrates triboelectric nanogeneration and ultralong persistent luminescence into one flexible unit─a combination that, to the best of our knowledge, has not been previously reported for all-night passive road marking applications with both liquid–solid and solid–solid energy harvesting modes. To overcome the moisture sensitivity and poor polymer compatibility of SAOED phosphors, a silicone-resin surface coating strategy is adopted. At the optimized coating ratio, the crystal structure is well preserved, the afterglow decay to 1.36 mcd/m2 exceeds 15 h, and the luminescence loss is below 10%. A liquid–solid triboelectric nanogenerator (TENG) based on this film delivers 150 nA and 1.8 V under water droplet impact, adapting well to varying rainfall intensities. A solid–solid TENG operating at 1 Hz produces a stable voltage of about 11 V and lights up over 40 LEDs. After UV excitation, the film emits bright blue-green light with CIE coordinates nearly identical to the neat phosphor, enabling “daytime storage, nighttime glow” while harvesting energy from raindrops and footsteps. Through this coating strategy, the interfacial compatibility and luminescence retention are synergistically enhanced, and the influence of PVDF content on dielectric, mechanical, and triboelectric properties is systematically revealed. This work provides a material platform for maintenance-free, all-weather, visually interactive self-powered road marking and smart traffic facilities.