PEP azide is a multifunctional dye used in various biological experiments to observe and analyze cell structures, track biomolecules, evaluate cell functions, distinguish cell types, detect biomolecules, study tissue pathology, and monitor microorganisms. Its applications range from basic scientific research to clinical diagnostics. Additionally, dyes have applications in traditional fields like textile dyeing, and emerging fields such as functional textile processing, food pigments, and dye-sensitized solar cells.