Inorganic salt templated porous TiO2 photoelectrode for solid-state dye-sensitized solar cells

Abstract

TiO₂ photoelectrodes with channels (or pores) are prepared by using an inorganic salt (NaHCO₃) as a template. NaHCO₃ doped TiO₂ slurries deposited on a compacted TiO₂ film are heated at 150 °C, which releases CO₂ gas and water vapour, thus forming channels (or pores) inside a TiO₂ light-scattering photoelectrode. These channels (pores) improve the penetration degree of solid-state electrolytes into the TiO₂ photoelectrode and enhance the photovoltaic efficiency of resulting DSSCs (dye sensitized solar cells). With a channel (pore) size of ∼500 nm diameter, an ionic liquid plastic crystal, 5-azoniaspiro[4.4]nonane bis(trifluoromethanesulfonyl)imide (N₄₄TFSI), shows power conversion efficiencies of 6.1% and 5.4% under 1.5 solar spectrum illuminations at 50 and 100 mW cm⁻², respectively.