Double-layer dye-sensitized solar cells using SrTiO<sub>3</sub> and BaTiO<sub>3</sub> second layer with enhanced photovoltaic performance

Abstract

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 (VOC) 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 VOC. By using the second layer, short-circuit current density (JSC) was also slightly improved (∼4%), possibly due to the increase of electrode thickness and light confinement effect for >∼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.