Guest-Induced Activation of Multicolor Photoluminescence in Naphthalene Bisimide Liquid Crystals

Achieving color- and lifetime-tunable emission in processable materials remains challenging, as most of the available advanced materials systems exist only in impractical solutions or hard-to-process crystals. Liquid crystals (LCs) represent a promising platform due to their processability, though previous work has mainly controlled emission color by external fluorophore doping. In this work, we present a supramolecular strategy to activate and tune both photoluminescence (PL) color and lifetime in naphthalene bisimide (NBI) LCs by embedding electron-rich guests. The electron-deficient NBIs form columnar hexagonal mesophases stabilized by nanosegregation of aromatic cores and aliphatic side chains, providing a suitable environment for charge-transfer (CT) interactions. Incorporating electron-rich polycyclic aromatics, carbazole derivatives, or square-planar Pt(II) complexes yields emissive CT states with tunable emission from visible to near-infrared (511-685 nm), covering short-lived fluorescence to long-lived delayed luminescence of coexisting thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP). Co-assembling two complementary NBI hosts with one guest enables an energy-transfer cascade that simultaneously supports green and red dual emission of fluorescence and TADF. This additive-induced activation and host-mixing approach greatly broadens the luminescence range accessible in LCs, combining tunable photophysical properties with intrinsic processability for next-generation optical encoding and security labeling technologies.