Enhancing DSSC Photoanode Performance by Using Ni-Doped TiO2 to Fabricate Scattering Layers

Titanium dioxide powder (TDP) and nickel-doped titanium dioxide powder (NiTDP) were synthesized by simple processes based on the sol–gel method. Nickel can be doped into titanium dioxide to narrow its energy bandgap; as a result, the visible-light photoactivity can be improved. In this study, the particle size of the fabricated TDP and NiTDP were larger than 100 nm, which is suitable for fabricating the light scattering layer (LSL) of the photoanode of dye-sensitized solar cells (DSSCs). The photoanode of our DSSCs comprised two layers: (1) a light absorbent layer made of commercial P25 titanium dioxide nanoparticles and (2) an LSL made of TDP or NiTDP. The DSSC used an organic MK-2 dye sensitizer, iodine-based redox electrolyte, and a multiwalled carbon nanotube counter electrode. Experimental results show that the photocurrent was significantly enhanced when the LSL was used. The DSSC with the absence of the LSL exhibited a conversion efficiency of 2.15%, while those of the DSSCs with the TDP-based LSL and NiTDP-based LSL were 2.37% and 2.78%, respectively. These results combined with UV–Vis spectra data, confirm the effectiveness of the extended visible-light photoactivity of the NiTDP-based LSL on the performance of the photoanode.