Dye-sensitized solar cells based on anatase TiO2 hollow spheres/carbon nanotube composite films

Dye-sensitized solar cells (DSSCs) based on anatase TiO2 hollow spheres (TiO2HS)/multi-walled carbon nanotubes (CNT) nanocomposite films are prepared by a directly mechanical mixing and doctor blade method. The prepared samples are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy and N2 adsorption–desorption isotherms. The photoelectric conversion performances of the DSSCs based on TiO2HS/CNT composite film electrodes are also compared with commercial-grade Degussa P25 TiO2 nanoparticles (P25)/CNT composite solar cells at the same film thickness. The results indicate that the photoelectric conversion efficiencies (η) of the TiO2HS/CNT composite DSSCs are dependent on CNT loading in the electrodes. A small amount of CNT clearly enhances DSSC efficiency, while excessive CNT loading significantly lowers their performance. The former is because CNT enhance the transport of electrons from the films to FTO substrates. The latter is due to high CNT loading shielding the visible light from being adsorbed by dyes.

Graphical abstractDye-sensitized solar cells based on anatase TiO2 hollow spheres/multi-walled carbon nanotube (<0.1 wt%) nanocomposite films display an enhanced photoelectric conversion efficiency.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Dye-sensitized solar cells (DSSCs) based on anatase TiO2 hollow spheres/multi-walled carbon nanotubes (CNT) nanocomposite films. ► The CNT loading obviously influences the textural properties and photoelectric conversion efficiency of DSSCs. ► Nanocomposite solar cells with low CNT loadings (<0.1 wt%) show enhanced photoelectric conversion efficiency. ► CNT reduce the electrolyte/electrode interfacial resistance and enhance the transport of electrons from the films to FTO substrates.