Electro chemical impedance spectrscopic analysis of Nb2O5 blocking layer in dye sensitised solar cells

Back electron transfer can be reduced by inserting an energy barrier layer at the interfaces of a photoanode is an effective method for improving the photovoltaic parameters in dye sensitised solar cells (DSSCs). In this work phase modified Nb₂O₅ blocking layer was inserted at the fluorine doped tin oxide (FTO) /TiO₂ interface by Rf magnetron sputtering process. For a tunnelling distance of ~40 nm, crystalline Nb₂O₅ blocking layer improved the efficiency close to 7% and outperformed the amorphous blocking layer. Longer electron lifetime in DSSCs having inhomogeneous Nb₂O₅ layer indicates that trapping de-trapping impedes the discharge of electrons to the TiO₂ band edge.