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

Abstract

A dye-sensitized solar cell (DSSC) architecture is presented with the high dielectric SrF2 incorporated into a semiconducting TiO2 photoanode (SrF2<bold>/</bold>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 (epsilon '=6.844 x 10(6)), 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 mu W<middle dot>cm(-2) under 1000 lx intensity by LED-5000K.