Retardation of charge recombination between hole conductors and TiCl₄:BaCl₂-Modified photoelectrodes in TiO₂-Based Solar Cells

The effects of a mixed overlayer composed of TiO₂ and BaTiO₃ on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surfaces of TiO₂ photoelectrode films were modified with TiCl₄:BaCl₂ mixed aqueous solutions with various molar ratios and then calcined to produce surface-modified TiO₂ photoelectrodes (Ti:Ba–TiO₂/FTO). The resulting films were applied to the photoelectrodes of DSSCs. The DSSCs with Ti:Ba(3:7)–TiO₂/FTO, which were prepared from a mixed solution with a molar ratio of 3:7 (TiCl₄:BaCl₂, showed a power conversion efficiency of 8.99% compared with theDelivered 8.23% conversion by Ingenta efficiency to: Elsevier of the BV reference cell with Ti:Ba(10:0)–_TiO2/FTO(i.e., a TiO2-only overlayer), due to enhancements in the short-circuit current (J_sc)and the open-circuit voltage (_{Voc. A)} series of measurements, including those on ultraviolet-visible absorption, electrochemical impedance, and dark currents, revealed that the incorporation of the mixed overlayer on the nanoporous TiO₂ photoelectrodes led to improvements in the light harvesting efficiency and the electron collection efficiency, thereby increasing the J_sc value. The increase in the V_oc value of the device with Ti:Ba(3:7)-TiO₂/FTO was caused by the reduced charge recombination between the photo-injected electrons and I₃⁻ ions.