Effect of surface modification of TiO2 on the photovoltaic performance of the quasi solid state dye sensitized solar cells using a benzothiadiazole-based dye

We report the preparation of nanoporous TiO2 electrode modified with an insulating material—BaCO3 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 BaCO3 modification significantly increases the dye adsorption, resulting from the fact that the surface of BaCO3 is more basic than TiO2. The performance of the DSSCs with and without BaCO3 modified TiO2 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 BaCO3 modified electrode as compared to bare TiO2 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 BaCO3 modified electrode is used instead of bare TiO2 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 TiO2 electrode is used.