Smart Multimodal Optical Film from Visible-Light-Excited Phosphorescent Materials for Daytime Light Intensity Modulation and Nighttime Traffic Safety

Smart optical films integrating multiple modalities (fluorescence, phosphorescence, transmission, and scattering) demonstrate significant potential for flexible displays and optical devices. However, fabricating such films remains challenging due to structural design complexity and material synthesis difficulties. Herein, a smart multimodal optical film (SMOF) is fabricated by embedding visible-light-excited phosphorescence nanoparticles (CD-SiO₂ NPs) within the polydimethylsiloxane (PDMS) matrix. Notably, the optical properties of SMOF are dynamically tunable through mechanical deformation and visible-light excitation, which effectively circumvent the intrinsic limitations of ultraviolet (UV) excitation. In the released state, the SMOF architecture demonstrates exceptional UV-vis transmittance, which is attributed to the similar refractive index between the PDMS and SiO₂ NPs. Concurrently, this film facilitates green-emissive fluorescence and phosphorescence under flashlight excitation, thereby eliminating UV-induced photodegradation. In addition, mechanical deformation will induce the formation of cracks and voids at the CD-SiO₂ NPs and PDMS matrix, which can amplify light scattering and enhance the ability of CD-SiO₂ NPs to absorb scattered light. These synergistic interfacial phenomena collectively govern the optomechanical switching behavior of the SMOF system, consequently achieving its broadband transmittance regulation while simultaneously amplifying the photoluminescence intensity. These distinctive optomechanical characteristics establish SMOF as a multifunctional platform, particularly suitable for stimuli-responsive privacy protection, UV-shielding applications, and persistent-luminescence-based traffic safety systems.