Multifunctional Optical Polymeric Films with Photochromic, Fluorescent, and Ultra‐Long Room Temperature Phosphorescent Properties

Abstract Photochromism, fluorescence, and ultra‐long room temperature phosphorescence (URTP) are attractive phenomena in photonics. However, achieving multiple optical properties such as photochromism, fluorescence, and URTP on one material still remains a challenge. Here, the authors report a multifunctional optical polymeric film with photochromic, fluorescent, and URTP properties, fabricated by simply doping the naphthopyran molecule into epoxy polymer with 3D network. When the polymer network is loose, the naphthopyran‐doped film exhibits photochromic property but no fluorescence and phosphorescence. When the polymer network becomes dense, the film shows fluorescent and URTP behaviors but no photochromic property. It is noted that the room temperature phosphorescence lifetime is as high as 604 ms. Based on the excellent optical properties of reversible photochromism, fluorescence, and URTP, an advanced sixfold encryption application has been successfully established. This work not only opens up a new direction in design and fabrication of multifunctional optical materials but also offers principles for developing organic optical materials toward multilevel information encryption and data storage.