Efficiency enhancement of flexible dye-sensitized solar cell with sol-gel formed Nb2O5 blocking layer

We investigated the effect of a Nb2O5 blocking layer formed through the sol-gel method introduced to a titanium metal foil electrode in a flexible dye sensitized solar cell. The blocking layer formed directly on the working electrode physically separates the working electrode from the electrolyte, and prevents back transfer of electrons from the electrode to the electrolyte. The gel processing conditions (sol reaction time) and heat treatment temperature used in formation of the Nb2O5 blocking layer have been shown to affect the performance of the dye sensitized solar cell and optimal values of these parameters have been determined. A sol reaction time of 45 min and heat treatment temperature of 550 degrees C has been observed to result in optimal cell performance (eta = 6.185%, J(sc) = 13.233 mA/cm(2), V-oc = 0.672 V, ff = 0.694). Introduction of an Nb2O5 blocking layer enhances solar cell efficiency by 39.7%, which is much greater than the increase of 24.6% observed in a similar cell containing a TiO2 blocking layer under standard illumination conditions. The results obtained via Nb2O5 have been observed to be superior to those obtained via a TiO2 blocking layer. (C) 2013 Elsevier B.V. All rights reserved.