Double-layer dye-sensitized solar cells using SrTiO3 and BaTiO3 second layer with enhanced photovoltaic performance

Double-layer electrodes using TiO2-P25 as the first layer and SrTiO3 or BaTiO3 as the second layer were prepared to improve photovoltaic performance of dye-sensitized solar cells (DSCs), since SrTiO3 and BaTiO3 have more negative conduction bands than that of TiO2. TiO2-anatase second layer with the similar particle size to these double oxides was also prepared as a comparison. Crystal structure, microstructure, film thickness, amount of dye adsorption, J-V curves and IPCE spectra were characterized. Open-circuit voltage (V-OC) of the DSCs with the SrTiO3 or BaTiO3 second layer was improved due to the inhibition of electron-hole recombination by the second layer at the top side of the TiO2 first layer. Elongation of the electron life time due to the band-structure matching might be another reason of the increase in V-OC. By using the second layer, short-circuit current density (J(SC)) was also slightly improved (similar to 4%), possibly due to the increase of electrode thickness and light confinement effect for >similar to 650 nm. As a result, the DSC using BaTiO3 second layer electrode had the largest conversion efficiency of 5.71% with an enhancement of 11.3% compared to that of TiO2-P25 single-layer electrode. (C) 2015 The Ceramic Society of Japan. All rights reserved.