Used as a redox mediator in dye-sensitized solar cells to enhance electron transfer and improve cell efficiency. Also applied in biochemical assays as a chromogenic substrate for enzyme detection, particularly in oxidase-based test systems. Its sulfonic acid group increases water solubility, making it suitable for aqueous reaction environments. Additionally, it serves as an intermediate in the synthesis of phenazine-based dyes and pharmaceuticals due to its stable aromatic structure and reactive hydroxyl groups.