Spatial arrangement of carbon nanotubes in TiO ₂ photoelectrodes to enhance the efficiency of dye-sensitized solar cells

Three electrode structures with different spatial arrangements of carbon nanotubes (CNTs) in the mesoporous TiO ₂ layer were employed in dye-sensitized solar cells to study the effect of surface states at the interface formed by the incorporation of CNTs. It was found that the decay of open circuit voltage (V _oc) was significantly minimized by avoiding the direct contact of nanotubes to the conducting substrate by introducing a thin buffer layer of TiO ₂ while maintaining the superior electron collection efficiency from the incorporation of nanotubes.