Effect of Interfacial Polarization on the Trap Passivation and Dielectric Constant of SrF₂/TiO₂ for Dye-Sensitized Solar Cells

A dye-sensitized solar cell (DSSC) architecture is presented with the high dielectric SrF₂ incorporated into a semiconducting TiO₂ photoanode (SrF₂/TiO₂). Polarization at the dielectric/semiconductor interface with the optimum composition of SrF₂/TiO₂ (%w/w 10/90) enhances the charge separation and dielectric constant of SrF₂/TiO₂ (ϵ′=6.844 × 10⁶), which tends to increase the charge transport kinetics and the charge collection efficiency of the DSSC by balancing the dye loading and the charge recombination at the photoanode. The strong electrostatic shielding of SrF₂ is responsible for the reduced recombination, which can impede the back electron transfer in a device, and the intermediate trap levels are passivated by electron filling through the interfacial polarization effect. The power conversion efficiency (PCE) was improved to 7.58% with respect to the reference DSSC (6.99%) at 1-sun illumination, while the PCE reached up to ca. 16.01% with a high output power of 59.41 μW·cm^-2 under 1000 lx intensity by LED-5000K.