Production of Nb doped TiO2 thin films and their application to dye sensitized solar cells

In this thesis, a dye-sensitized solar cell, which is used in the direct conversion of solar energy from renewable energy sources into electrical energy, was produced by adding a blocking layer to its structure. Undoped and Nb-doped TiO2 thin films as blocking layer were produced by dip coating method on FTO coated glass substrate. Doping was done at 1%, 3%, 5% and 7% volume ratios. The structural, optical and surface properties of the produced blocking layers were investigated. TiO2 film as mesoporous metal oxide was produced on FTO substrate by doctor blade method. The structural, optical and surface properties of the mesoporous TiO2 film were investigated. FTO/m-TiO2 film structure was dipped into the prepared N719 dye solution and the photoelectrode showing the highest absorption at different dipping times was determined. Dye dipping was also applied to the FTO/Blocking layer/TiO2 structure for the specified time, and the photoelectrodes were produced. The optical properties of the photoelectrodes obtained in this way were compared. Pt film as counter electrode was produced on FTO coated glass base by doctor blade method, and its structural and optical properties were determined. A Nb-doped dye-sensitized solar cell was produced by combining the photoelectrode and counter-electrode with the closed cell method. I-V measurement was taken under AM 1.5 illumination. In I-V measurements, it was determined that the efficiency values changed according to the blocking layer used. The highest efficiency with 4.68% was obtained from the dye-sensitized solar cell using 3% Nb-doped TiO2 barrier layer. High efficiency is associated with the high optical transmittance and high surface roughness of the 3% Nb-doped TiO2 blocking layer.