Preparation of surface-tethered polymer layer on inorganic substrates by photoreactive self-assembled monolayer

A self-assembled monolayer (SAM) that has benzophenone (BP) terminal group was prepared on Si and indium-tin oxide (ITO) substrates, on which poly(9-vinyl carbazol) (PVK) was spin-coated and then irradiated with ultraviolet (UV) light. Upon UV irradiation, the BP unit reacted with the PVK backbone, yielding a crosslinked PVK layer that was covalently tethered to the substrate surface. Using this procedure, a patterned thin film of PVK was obtained by irradiating UV light through a photomask and then rinsing in chloroform. When polystylene (PSt) was spin-coated on the BP-SAM, only a thin interfacial layer was tethered by UV irradiation because PSt does not crosslink upon UV irradiation. The BP-SAM improved the adhesion strength between the PVK layer and ITO substrate without reducing the carrier injection from ITO to PVK. The photoreactive BP-SAM appeared to be an effective method to improve the interface between an inorganic electrode and a polymer layer deposited on its surface.