Dye-sensitized solar cells based on multiwalled carbon nanotube-titania/titania bilayer structure photoelectrode

Dye-sensitized solar cells (DSSCs) were fabricated using multiwalled carbon nanotube (MWCNT)-TiO(2) nanocomposite as a light scattering layer. Morphology of the MWCNT-TiO(2) film was investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM and TEM images demonstrate that MWCNTs and TiO(2) nanoparticles can be dispersed with chitosan. Internal resistance in the DSSC was characterized by electrochemical impedance spectroscopy (EIS). EIS results reveal a decrease in the charge resistance of electrolyte/dye/MWCNT-TiO(2)/TiO(2) interface with increasing MWCNT content up to 3 wt% which leads to an improvement in the photovoltaic performance. Compare with a nanocrystalline TiO(2) single-layer cell, the DSSC based on the MWCNT (3 wt%)-TiO(2)/TiO(2) bilayer structure photoelectrode shows ~100% increase in solar-to-electric energy conversion efficiency, which is attributed to the inclusion of MWCNTs in TiO(2) matrix.