Investigations on the photo catalytic activity of calcium doped TiO2 photo electrode for enhanced efficiency of anthocyanins based dye sensitized solar cells

Abstract

The rich photo catalytic activity (PCA) of TiO2 deteriorates the photovoltaic performance of natural dye sensitized solar cells (DSSC) on irradiation. To improve the stability of natural dye in DSSC, the PCA of TiO2 must be passivated or reduced, without affecting the electron transfer kinetics. UV filters can be employed to avoid the direct band gap excitation in TiO2. But the blocking of photons in UV region decreases the Incident Photon to current Conversion Efficiency (IPCE) of the solar cell. Taking this factor into consideration, virgin and calcium (1%, 2%, 3%, 4% and 5%) doped TiO2 photo electrodes were grown by one step hydrothermal method on Fluorine doped Tin Oxide (FTO) substrates. The structural, morphological and optical properties of Ca doped nanorods passivate the free electrons on the TiO2 surface, thereby minimizing the PCA in the film. The 3% Ca doped TiO2 nanorods exhibited higher resistance to PCA when compared undoped TiO2 photo electrode. This increased the photovoltaic conversion efficiency of rose dye sensitized DSSC to 2.32%.