Fabrication of dye-sensitized solar cells with multilayer photoanodes of hydrothermally grown TiO2 nanocrystals and P25 TiO2 nanoparticles

TiO 2 nanocrystals (NCs) with sizes around 20 nm were synthesized by hydrothermal method in acidic autoclaving pH. The hydrothermally grown TiO 2 NCs and P25 TiO 2 nanoparticles (NPs) were used in the preparation of two different pastes using different procedures. These pastes with different characteristics were separately deposited on FTO glass plates to form multilayer photoanodes of the dye-sensitized solar cells. The aim of this study was to search how a thin sub-layer of the hydrothermally grown TiO 2 NCs in the photoanodes could improve the efficiency of TiO 2 P25-based solar cells. The highest efficiency of 6.5% was achieved for a cell with a photoanode composed of one transparent sub-layer of hydrothermally grown TiO 2 NCs and two over-layers of P25 NPs. Higher energy conversion efficiencies were also attainable using two transparent sub-layers of hydrothermally grown TiO 2 NCs. In this case, an efficiency of 7.2% was achieved for a cell with a photoelectrode made of one over-layer of P25 TiO 2 NPs. This could show an increase of about 30% in the efficiency compared to the similar cell with a photoanode made of two layers of hydrothermally grown TiO 2 NCs.