Efficient light-scattering functionalized TiO2 photoanodes modified with cyanobiphenyl-based benzimidazole for dye-sensitized solar cells with additive-free electrolytes

Abstract

Light-scattering functionalized cyanobiphenyl-based benzimidazole was synthesized and applied in the surface modification of dyed TiO₂ photoanodes for dye-sensitized solar cells (DSSCs). DSSCs based on the ionic liquid and all-solid-state electrolytes were fabricated and characterized, without the addition of additives in the electrolytes. Compared with electrolytes containing the additive N-butylbenzimidazole (NBB), surface modification of dyed TiO₂ photoanodes with cyanobiphenyl-based benzimidazole could enhance the values of the open-circuit photovoltage (V_oc), short-circuit photocurrent density (J_sc) and the overall PCE of the fabricated DSSCs, due to the suppressed charge recombination rate, the conductivity optimization of the electrolytes and enhanced light harvesting capability at the TiO₂ photoanode/electrolyte interface. Under the simulated air mass 1.5 solar spectrum illuminations at 100 mW cm⁻², the fabricated devices achieved a cell efficiency of ∼6.63% and ∼5.82% for ionic liquid and all-solid-state electrolytes, respectively. These results provide an alternative strategy for high performance DSSCs with additive-free electrolytes.