From Hard Crystal to Soft Fiber: Thermochromic Color‐Tunable and “On‐Off”‐Switchable Afterglow of Single‐Component Ultralong RTP Organogel

Abstract Pure organic stimuli‐responsive phosphorescent materials with multi‐color afterglows, good reversibility, and ease manipulation are highly appealing for dynamic anti‐counterfeiting applications, but remain challenging to achieve. In this work, a phosphorescent soft organogel is rationally designed by introducing functional carbonyl (benzoyl or acetyl) units into dibenzofuran skeleton to promote the intersystem crossing (ISC), and screening potential organogelators through predicting the self‐assembly process with the aid of all‐atom molecular dynamic simulation (AMDS). AMDS indicates that the designed gelator candidates ( DBF‐Me and DBF‐Ph ) can self‐assemble in the mixture of DMSO/H 2 O through balanced π‐π intermolecular interactions between neighboring molecules, thus promoting the gelation. Notably, the DBF‐Ph fiber gel exhibits a yellow afterglow at room temperature (298 K) with a lifetime of 235.1 ms, which can be switched off at 358 K but restored after cooling to room temperature. Furthermore, the yellow afterglow (298 K) can turn to green at 208 K and blue at 77 K, due to the slight change of conformation and molecular packing as revealed by analysis of temperature‐dependent single crystal structures. This single‐component DBF‐Ph fiber gel, capable of achieving color‐tunable and “on‐off”‐switchable afterglow through a single temperature response, offers significant potential in developing soft ultralong RTP materials for multi‐level anti‐counterfeiting features.