Used in organic synthesis as a key intermediate for pharmaceuticals and functional materials. Its sulfonyl chloride group readily reacts with amines and alcohols, making it valuable for constructing sulfonamide and sulfonate ester derivatives. Commonly applied in the development of organic semiconductors, particularly in hole-transport materials for OLEDs and perovskite solar cells. Also employed in the preparation of fluorescent dyes and sensors due to the inherent photophysical properties of the carbazole core. Its rigid aromatic structure enhances thermal and oxidative stability in resulting compounds, beneficial for optoelectronic applications.