Circularly Polarized Ultralong Room-Temperature Phosphorescence Photonic Crystal Film with High Dissymmetry Factor and Multi-Color Afterglow

Abstract

Manufacturing the circularly polarized room-temperature phosphorescence (CP-RTP) materials with both a high dissymmetry factor (g_lum) and ultralong lifetime is significant, but it is greatly challenging owing to the difficulty of satisfying the stable triplet exciton and matched chirality simultaneously. In this work, the RTP material is synthesized by doping the chromophores into the poly(vinyl alcohol) (PVA) matrix. The rigidity surrounding and the compact hydrogen bond interactions contribute to the long-lived phosphorescent emission. On this basis, the RTP assembly is imported into the cellulose-based chiral liquid crystal matrix to produce the CP effects. By optimizing the photonic bandgap structure, this nanofilm integrates a large g_lum of −0.2881, blue-green afterglow over 50 s, and an ultralong room-temperature lifetime of 4.129 s. Next, this work utilizes the selective optical reflection to switch the handedness direction of CPL, which resolves the inherent limitation of a single chiral luminescent direction, and the inverted g_lum reaches 0.2379. Then, by introducing the organic dyes, multi-color chiral phosphorescence is realized under the efficient energy transfer between the host film and guest dyes. Finally, the CP-RTP nanofilm, characterized by multimodal and convertible optics and green manufacturing, is applied in the optical anti-counterfeiting areas.