Thermally Activated Delayed Fluorescence in Aqueous Solution: Preparation, Performance, and Biomedical Application

ABSTRACT Thermally activated delayed fluorescence (TADF) materials exhibit promising potential in the biomedical field, owing to their advantageous characteristics such as long luminescence lifetime and high fluorescence quantum yield (FLQY). However, most currently developed TADF materials have poor water solubility, which poses a significant limitation for their direct biological applications. To address this challenge and broaden their applicability in biology, the synthesis of TADF in aqueous solution has emerged as a crucial research direction in recent years. This review focuses on the latest research progress concerning TADF in aqueous solution for biomedical applications. Starting from the classification of TADF materials, it summarizes their construction strategies, performance modulation, and biomedical applications. First, based on the different methods to achieve TADF in aqueous solution, the construction strategies are categorized into three types: the matrix confinement, the self‐assembly, and the aggregation‐induced. The discussion covers the modulation of their key photophysical properties, including emission wavelength, luminescence lifetime, and FLQY. Subsequently, the review elaborates on the principles and recent advances of these materials in bioimaging, photodynamic therapy, and biosensing. Finally, the future challenges and opportunities for TADF in aqueous solution in the biomedical field are outlined, aiming to provide insights for their rational design and widespread application.