Dye-sensitized solar cells based on two-dimensional TiO2 nanosheets as the scattering layers

Abstract

Two-dimensional (2D) TiO2 nanosheets with high crystallinity and good light scattering properties were synthesized via a simple solvothermal process using reduced graphite oxide as a sacrificing template. X-ray diffraction patterns and electron microscopy images indicated that the prepared 2D TiO2 nanosheets were composed of high-crystalline anatase TiO2 nanoparticles. Then, the 2D anatase TiO2 nanosheets were used as a scattering layer of the photoelectrode, which is expected to produce high-efficiency dye-sensitized solar cells (DSSCs). Compared with ones with pure TiO2 nanoparticle photoelectrodes, DSSCs based on 2D TiO2 nanosheets as middle scattering layer yield the highest photoelectrical conversion efficiency of 7.54 %. This is because the obtained 2D TiO2 nanosheets have excellent light scattering, allowing for fast interfacial charge transfer, the least series resistance, and the best charge collection efficiency. These have been systematically evidenced by the electrochemical impedance spectra, intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy.