When the molecules are in a low concentration state, they are independent of each other and can emit fluorescence. The principle of aggregation-induced fluorescence quenching is that when the molecules are in low concentration, they are independent of each other and can emit fluorescence; However, when the molecular concentration increases, aggregation or accumulation may occur, resulting in the decrease of intermolecular distance and affecting the interaction between molecules. Aggregation-induced quenching (AIQ) refers to the phenomenon that the fluorescence intensity of molecules will decrease significantly at high concentration or high aggregation state.