High-Throughput Electrospinning System| Multicolor Rare-Earth Film with Ultra-Long Afterglow forDiverse Energy-Saving Applications

Yangzhou University’s Pang Huan and Tian Tian Team Publishes in Advanced Materials: Ultra-Long Afterglow Luminescent Film Opens New Energy-Saving Application Scenarios

Rare-earth long-afterglow materials exhibit revolutionary potential in high-end anti-counterfeiting, biomedical imaging, and smart optoelectronic sensing due to their unique light-trapping and delayed-emission properties. These materials can emit light persistently after excitation ceases, offering innovative solutions for passive lighting and dynamic information encryption. However, traditional rare-earth afterglow systems face multiple technical bottlenecks due to inherent material limitations: their rigid crystal structures result in poor interfacial compatibility with flexible substrates, hindering complex morphology construction via solution processing; their single emission band and difficult tunability limit full-spectrum display requirements; and environmental humidity/temperature variations easily cause deactivation, restricting stable outdoor applications. Although recent progress in composition optimization and structural design has improved afterglow performance, overcoming the trade-offs among flexibility, multicolor emission, and environmental stability—while developing scalable flexible device integration—remains a critical challenge.

To address this, a collaborative team from Yangzhou University (Pang Huan, Tian Tian) and Sun Yat-sen University (Chen Yuxin) proposed a multicomponent synergy strategy based on electrospinning. By combining electrospinning with functional material hybridization, they used flexible poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as a substrate to precisely control the spatial distribution and interfacial interactions of red/green/blue rare-earth phosphors ((Sr₀.₇₅Ca₀.₂₅)S:Eu²⁺, SrAl₂O₄:Eu²⁺,Dy³⁺, and Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺) with ZnS, fabricating a multicolor afterglow film (RMAF) measuring 0.4 m × 3 m. The film achieves synergistic multicolor emission and ultra-long afterglow (>30 hours), a photoluminescence quantum yield of 68.8%, and excellent photothermal response/environmental adaptability, showing promise for emergency signage and smart agriculture. The study, titled Multicolor Rare-Earth Film with Ultra-Long Afterglow for Diverse Energy-Saving Applications, was published in Advanced Materials (DOI: 10.1002/adma.202417420).

Figure 1. Schematic diagram of RMAF preparation, images of RMAF emitting red, blue, green, and white afterglow, and morphological characterization.

Performance enhancement stems from PVDF-HFP and ZnS synergy: PVDF-HFP’s polarized electric field (from fluorine’s electronegativity) optimizes rare-earth ion distribution and reduces photon loss, while ZnS acts as a deep-trap modulator, creating an energy-recycling network via oxygen vacancies. The proposed "multi-channel energy transfer–deep-trap storage" mechanism explains dynamic coupling between rare-earth 4f-5d transitions and defect states. Heterojunctions at ZnS/phosphor interfaces accelerate carrier separation; deep traps preferentially store high-energy electrons; and cascaded trap release enables sustained emission.

Figure 2. Chemical characterization of the long-afterglow film.

To validate this mechanism, the research team conducted systematic investigations using multiple characterization techniques. XPS analysis revealed the polarization of fluorinated groups, alterations in the electronic environment of C-F bonds, and the formation of semi-ionic fluorine, confirming that PVDF-HFP stabilizes phosphor dispersion through strong electrostatic interactions. EPR measurements demonstrated the critical role of ZnS in enhancing oxygen vacancy concentration, thereby providing deep traps for carrier capture. Photocurrent response experiments (showing a 4.65-fold increase) indicated the energy-level coupling effect between ZnS and Eu²⁺, facilitating photon energy transfer and recycling.The combination of variable-temperature XRD and thermoluminescence spectroscopy unveiled the synergistic mechanism among multiple components: the deep traps formed by BLUE, GREEN, and RED phosphors enable stepwise energy transfer, while the narrow bandgap characteristic of RED (621 nm) enhances red-light utilization efficiency. This multiscale interaction extended the film's afterglow duration from 12 hours to over 30 hours and increased the quantum yield to 68.8%.The elucidation of these microscopic mechanisms provides crucial theoretical support for designing flexible long-afterglow materials that simultaneously achieve high luminescence efficiency and environmental stability.

Figure 3. Mechanism design and patterned afterglow display.

Figure 4. Application in firefighting suits.

Figure 5. Application in intelligent optical plant greenhouses.

Figure 6. Schematic diagram of applications in road and tunnel lighting.

In practical application demonstrations, the research team selected firefighting protective suits and greenhouse cultivation systems as models to showcase the application potential of RMAF films in extreme environment visibility and agricultural light regulation. Thermoluminescence experiments revealed that the RMAF film achieves autonomous luminescence through a temperature-stimulated carrier release mechanism, and when integrated into protective clothing, it can provide emergency illumination in high-temperature environments.For greenhouse systems as complex light-regulation scenarios, the inherent diurnal light intensity fluctuations may limit the effectiveness of conventional supplemental lighting equipment. Remarkably, the RMAF film successfully achieved 24-hour cyclic red light compensation (621 nm wavelength accounting for 22.1% of emission), resulting in a 39.4% increase in wheat chlorophyll content, demonstrating its groundbreaking capability in precision agriculture light management. In the final tunnel lighting application, the film exhibited exceptional vehicle light capture capability at distances up to 70 meters, highlighting its energy-saving advantages in large-area low-illumination environments.

In conclusion, building upon the first discovery of the deep-trap regulation mechanism through rare-earth phosphor-ZnS composites, the research team employed an innovative strategy combining electrospinning with multicomponent rare-earth hybridization. This approach significantly enhanced the afterglow performance, light-harvesting capacity, and environmental stability of rare-earth materials, achieving simultaneous improvement in broad-spectrum energy capture and recycling efficiency. The successful fabrication of large-area (0.4m × 3m) scalable multicolor light-regulation films with ultra-long afterglow (>30 hours) properties and validated high-efficiency energy storage performance represents a major advancement. These findings not only provide crucial theoretical foundations and technical paradigms for rare-earth material applications in energy-saving technologies, but also reveal their industrial application potential in emerging fields such as sustainable lighting technology, intelligent agricultural light compensation systems, and public safety emergency visualization through breakthrough material performance.

Paper link: https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202417420