Dual-state emission, stretchability, information encryption, and intrinsic mechanism based on a butterfly shaped...

Flexible materials with dual-state emission, featuring thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), remain relatively rare, and the influence of different rigid and flexible doping matrices on the luminescence and stretchability properties of dual state emission luminogens are obscure. Here, a butterfly-shaped molecule named AN-Br was successfully prepared, presenting strong phosphorescence emission and dual-state emission in glassy THF and DMSO solutions respectively. By choosing different rigid and flexible doping matrices, luminescence and stretchability properties of AN-Br were investigated. The results demonstrated that AN-Br had similar dual-state emission in both rigid and flexible matrices, but with different RTP lifetimes ranging from 280.85 ms to 616.24 ms and afterglow durations from 4 s to 9 s, as well as time and temperature dependent dynamic afterglows. Notably, 0.5% AN-Br@PVC film presented obviously reduced RTP emission intensity and lifetime, as well as completely disappearing TADF emission with increasing strain, while 0.5% AN-Br@SIS film showed relatively stable RTP and TADF emission intensities and lifetimes. Moreover, 0.5% AN-Br@PVC and 0.5% AN-Br@SIS film exhibited excellent flexibility, especially for 0.5% AN-Br@SIS film with an elongation at break of 1000%. Long-lived red afterglow materials and high-level information encryptions were also achieved by constructing two ternary doping systems and leveraging the distinct afterglow colors and durations. The work not only expands the application scope of dual-state emission materials in strain sensing but also elucidates the luminescence properties and underlying mechanisms of dual-state emission in various matrices, thereby advancing technological progress and innovative development of flexible dual-state emission materials.