BaCO3 modification of TiO2 electrodes in quasi-solid-state dye-sensitized solar cells:: Performance improvement and possible mechanism

In this paper, a nanoporous TiO2 electrode modified with an insulating materialBaCO(3)is synthesized for quasi-solid-state dye-sensitized solar cells (DSSCs). The formation of BaCO3 is confirmed from the X-ray photoelectron spectrum (XPS) and Fourier transform infrared (FTIR) spectrum, while the components of the modified TiO2 film are studied by electron-probe microanalysis (EPMA). We find that BaCO3 modification remarkably increases dye adsorption, resulting from the fact that the surface of BaCO3 is more basic than that of TiO2. When applied to quasi-solid-state DSSCs, BaCO3-modified TiO2 electrodes have an increased open-circuit photovoltage (V-oc) and improved overall conversion efficiency (eta). The eta value improves from 5.53 to 6.96% by 25.9% under 30 mW/cm(2). The mechanism of BaCO3 modification is analyzed using the transient photovoltage spectra, open-circuit photovoltage spectra, and dark current measurement. The results indicate that in the presence of BaCO3, the TiO2 conduction band shifts to the negative direction.