The prevention of back electron transfer by inserting an energy barrier layer at the interface of a photo-anode is an effective method for improving the photovoltaic parameters in dye sensitised solar cells (DSSCs). In this study, phase a modified Nb2O5 blocking layer was inserted at the fluorine doped tin oxide (FTO)/TiO2 interface via a Rf magnetron sputtering process. For a critical tunnelling distance of ∼40 nm, the crystalline Nb2O5 blocking layer improved the efficiency close to 7% and outperformed the amorphous blocking layer by about 68%. The longer electron lifetime observed in DSSCs containing an inhomogeneous Nb2O5 layer indicates that trapping/de-trapping impedes the discharge of electrons to the TiO2 band edge. The origin of the longer electron lifetime is explained by formulating a theory from photovoltage decay measurements.
S. Suresh, Deepak, T. Gangadhara, Ni, C., Dr. Sreekala C. O., Satyanarayana, M., A. Nair, S., and Pillai, V. Pappukkuty, “The Role Of Crystallinity Of The Nb2O5 Blocking Layer On The Performance Of Dye-Sensitized Solar”, New Journal of Chemistry, vol. 40, 7 vol., pp. 6228-6237, 2016.