The electronic role of the TiO2 light-scattering layer in dye-sensitized solar cells

Dye-sensitized solar cells have been fabricated with different kinds of TiO2 films including SiO2 coated and bare TiO2 microparticles as light-scattering layer (LSL). Results show that the LSL barely affects the cell's dark current, whereas under illumination, it made a significant contribution to the total photocurrent. Photo-voltage decay measurements performed under bias illumination show the density of electronic states (DOS) of the LSL to be two times smaller than that of a transparent nanoparticle layer (TNL). Strikingly, DSCs fabricated from a 4.5 mu m thick LSL alone showed a conversion efficiency of 5% despite of being pate pink in color. This impressive performance is attributed to light containment in the LSL and a low density of defect electronic states.