Multifunctional organized mesoporous tin oxide films templated by graft copolymers for dye-sensitized solar cells

The synthesis of organized mesoporous SnO₂ films with high porosity, larger pores, and good interconnectivity, obtained by sol-gel templating with an amphiphilic graft copolymer, poly(vinyl chloride)-graft-poly(oxyethylene methacrylate), is reported. An improved performance of dye-sensitized solar cells (DSSCs) is demonstrated by the introduction of a 400 nm thick organized mesoporous SnO₂ interfacial (om-SnO₂ IF) layer between nanocrystalline TiO₂ (nc-TiO₂) and a fluorine-doped tin oxide substrate. To elucidate the improved efficiency, the structural, optical, and electrochemical properties of the devices were characterized by SEM, UV/Vis spectroscopy, noncontact 3D surface profilometry, intensity-modulated photocurrent/voltage spectroscopy, incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy measurements. The energy-conversion efficiency of the solid polymerized ionic liquid based DSSC fabricated with the om-SnO₂ IF/nc-TiO₂ photoanode reached 5.9 % at 100 mW cm^-2; this is higher than those of neat nc-TiO₂ (3.5 %) and organized mesoporous TiO₂ interfacial/nc-TiO₂ layer (5.4 %) photoanodes. The improved efficiency is attributed to the antireflective property, cascadal energy band gap, good interconnectivity, and high electrical conductivity of the om-SnO₂ IF layer, which results in enhanced light harvesting, increased electron transport, reduced charge recombination, and decreased interfacial/internal resistance. Peeling back the layers: An organized mesoporous SnO₂ (om-SnO₂) film is prepared using a graft copolymer as a template for dye-sensitized solar cells (DSSCs). The improved efficiency is attributed to the antireflective property, cascadal energy band gap, good interconnectivity, and high electrical conductivity of the film.