TPE-PY is a fluorescent dye designed for mitochondria, characterized by its cationic and lipophilic properties, enabling it to specifically target mitochondria. It operates via an aggregation-induced emission (AIE) mechanism by restricting intramolecular rotation (RIR), thereby enhancing fluorescence in the aggregated state. TPE-PY is primarily utilized in bioimaging, particularly for specific staining of mitochondria in live cells, assisting in the observation of mitochondrial location, morphology, and quantity.