Improved efficiency of dye-sensitized solar cell based on randomly ordered pore structure fabricated by dry deposition method

Porous TiO2 films were deposited onto FTO (fluorine doped tin oxide) substrate through dry deposition method, and polystyrene (PS) beads used as a sacrificial material. In addition, pore size was controlled by introducing 50-nm- and 300-nm-sized PS beads. Moreover, the improved porous film was obtained by varying weight ratios of TiO2 and PS powders to enhance DSSCs (dye-sensitized solar cell) efficiency. The DSSC with improved porous structure has shown efficiency of 6.8% with weight ratio (71.5%), which higher than that of only TiO2 layer (6.08%) and other compositions. The IPCE analysis showed the maximum absorbance over the wavelength range of 550-800 nm resulted in higher efficiency. EIS results indicated that the electron generation and transfer properties of porous films were better than that of the TiO2 layer only. From photovoltage decay measurement, the carrier lifetime was found to be longer in the porous structure than that of TiO2 layer only. Then, we proposed formation mechanism of porous films and their relation for effective scattering/absorbance of light. Moreover, the porous structure also enhances the specific surface area for higher amount of dye loading. Therefore, deposition of porous films could improve the efficiency of DSSCs using facile process.