Effect of surface modification of TiO 2 on the photovoltaic performance of the quasi solid state dye sensitized solar cells using a benzothiadiazole-based dye

Abstract

We report the preparation of nanoporous TiO 2 electrode modified with an insulating material—BaCO 3 and used as electrode for quasi solid state dye sensitized solar cells (DSSCs), with a benzothiadiazole-based dye (BTDR2) as sensitizer and PEDOT:PSS coated FTO as counter electrode. We found that the BaCO 3 modification significantly increases the dye adsorption, resulting from the fact that the surface of BaCO 3 is more basic than TiO 2. The performance of the DSSCs with and without BaCO 3 modified TiO 2 electrodes were analyzed by cyclic voltammograms, optical absorption spectra, current–voltage characteristics in dark and under illumination and electrochemical impedance spectra. The photovoltaic performance has been significantly improved for the BaCO 3 modified electrode as compared to bare TiO 2 electrode having the same other components in the DSSCs. The value of the overall power conversion efficiency ( η) improves from 2.42% to 4.38% under illumination intensity, when BaCO 3 modified electrode is used instead of bare TiO 2 electrode. The improvement in η has been attributed to the increased dye adsorption, reduction in recombination rate and enhancement in the electron lifetime when the modified TiO 2 electrode is used.