Used primarily as a hole-transport material in perovskite solar cells and organic light-emitting diodes (OLEDs). It helps improve device efficiency by facilitating the movement of positive charges from the active layer to the electrode. Its spirobifluorene core provides good thermal stability and film-forming properties, making it suitable for thin-film applications. Commonly doped with additives like lithium salts or cobalt complexes to enhance conductivity. Also employed in some organic photovoltaics and as an interfacial layer in optoelectronic devices.