长余辉材料是指在激发源停止后仍能持续发光的一类特殊发光材料。由于其能有效消除背景光和激发光干扰，提高生物成像精度，因此在生物成像领域具有重要应用前景。与无机长余辉材料相比，有机长余辉材料具有合成修饰容易、分散性佳、生物相容性好等优点，在生物成像应用领域具有明显优势。研究表明，尽管传统的双光子比单光子激发生物成像技术有更深的活体组织穿透能力并大幅降低活体细胞光损伤的优点，但是其仍使用持续高强度近红外激光照射，在焦点附近仍然会出现光漂白和活体细胞损伤。本项目在前期研究的基础上，拟把聚集诱导发光(AIE)、双光子、长余辉和调控单-三线态系间窜越效率等有机分子设计思想整合在一起，创新性地设计出融合了AIE强固体发光、双光子激发和长余辉三者优点的高效双光子激发有机长余辉材料，实现瞬时激发和高效持续发光，对降低近红外激光照射的损伤增加组织穿透深度、消除背景光和激发光干扰提高生物成像精度具有重要的作用。

Long afterglow materials are a kind of special luminescent materials that can continuously emit light after switching off the irradiation of excitation light source. It can effectively eliminate the interference of background light and excitation light and thus improve the accuracy of bio-imaging, which has an important application prospect in the field of biological imaging. Compared with the inorganic long afterglow materials, the organic long afterglow materials have the advantages of easy synthesis and modification, good dispersion, good biocompatibility, etc., and have obvious advantage in the field of biological imaging application. Studies have shown that although the traditional two-photon-excited bio-imaging technology has the advantages of deeper penetration in vivo tissue and significantly reduced the light damage of living cells, it still use continuous high-intensity near-infrared laser irradiation, and the light bleaching and living cell damage will still occur near the focus. On the basis of our previous studies, in this project, we creatively integrate the design strategies of aggregation-induced emission (AIE), two-photon-excited, long afterglow and controlling intersystem crossing efficiency between single and triplet states of organic molecules, to design two-photon-excited highly-efficient long afterglow materials that incorporate the advantages of AIE strong solid luminescence, two-photon excitation and long afterglow. The materials can realize the instantaneous excitation and efficient continues long afterglow emission, which is very useful for lowering the damage of near infrared laser irradiation, increasing tissue penetration depth, eliminating of background light and excitation light interferences to improve the biological imaging accuracy.