Multilevel stimulus-responsive smart organic afterglow materials beyond crystal limitations: Aqueous-phase dual emission afterglow and upconversion afterglow under ultra-wide range excitation

Organic afterglow materials hold significant potential for applications in information storage, anti-counterfeiting, and biological imaging. However, studies on afterglow materials capable of ultra-wide range excitation and emission simultaneously are limited. To enhance the practicality of strong emission single-component organic afterglow systems, overcoming the constraints of crystalline or other rigid environments is essential. We have developed solid-state dual-persistent thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) emissions spanning yellow to red under visible light excitation, utilizing a single-molecule terminal group regulation strategy. The RTP lifetime extends from 4.19 ms to 399.70 ms. These afterglow materials exhibit an ultra-wide absorption range from 200 nm to 800 nm, rendering them capable of being excited by both sunlight simulator and near-infrared radiation. The upconversion phosphorescence lifetime under 808 nm excitation reaches 13.72 μs. The double persistent emission of these compounds is temperature-sensitive. Moreover, following grinding or heat treatment, accompanied by extensive afterglow color conversion due to planarization of excited state conformations and additional efficient k_RISC generation. In addition, the amorphous state post melt annealing facilitates the afterglow transition from yellow to green. Crucially, these compounds also maintain stable ultra-long afterglow emission in aqueous and acid-base environments. Overall, we have successfully developed a series of single-component intelligent luminescent materials that demonstrate significant benefits, including dual TADF and RTP emissions, adjustable afterglow lifetimes, a broad range of excitation and emission wavelengths, multi-modal luminescence not restricted to crystalline states, and robust afterglow performance in challenging environments, setting the stage for the practical deployment of afterglow materials in engineering applications, the upconversion afterglow emission also holds promising potential for applications in the field of biological imaging.