TOF‐GISANS investigation of polymer infiltration in mesoporous TiO₂ films for photovoltaic applications

Abstract

Abstract The structure of porous TiO 2 films and TiO 2 :poly( N ‐vinylcarbazole) (PVK) composite films is investigated with time‐of‐flight grazing incidence small‐angle neutron scattering (TOF‐GISANS). The TiO 2 films have been prepared by application of a sol–gel process with a diblock copolymer as structure directing agent, and the conductive polymer PVK is infiltrated in the porous network by spin coating and solution casting. The films show a hierarchical pore structure with mesopores 52 nm in size and additional large macropores with a diameter of about 180 nm. By matching the scattering contrast of the TiO 2 with the polymer information about the penetration of the polymer in the pores is determined. Whereas in the PVK film prepared by solution casting the pores are filled to a high degree; in the spin coated film, PVK wets only the TiO 2 pore walls and forms a solid overlying layer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1628–1635, 2010