Synthesis of Oxide Layer Coated ZnO and TiO2 Nanoparticles and Their Application in Dye Densitized Solar Cells

Abstract

ZnO and TiO2 nanoparticles are very promising materials for dye-sensitized solar cells (DSSCs) because of their unique properties such as bandgap, chemical stability, high electron mobility, nontoxicity. A DSSC comprises of a dye adsorbed semiconductor (TiO2, ZnO) electrode, and a liquid electrolyte containing redox couple sandwiched between two transparent conductive oxide (TCO) glasses. However, the efficiency of DSSCs is limited due to the charge recombination of the semiconductor with the dye or the electrolyte used. The research work is, therefore, mainly aimed at, to reduce the charge recombination problem. The problem has been resolved using a synthesized oxide layer (Eu2O3, CaCO3) coated semiconductor nanoparticles (ZnO, TiO2) as photoelectrode. For the syntheses of ZnO and TiO2 nanoparticles, respectively, the chemical precipitation and sol-gel techniques have been used whereas, for the oxide layer coating on the surface of nanoparticles (TiO2 and ZnO), the hydrothermal method has been employed. Four different combinations (Eu2O3/ZnO, CaCO3/ZnO, Eu2O3/TiO2, and CaCO3/TiO2) have been taken. Their structural and compositional studies have been carried out using XRD and EDAX; morphological analysis using SEM/TEM; optical studies using FTIR and PL. To determine the amount of dye adsorbed on the fabricated electrodes, UV-visible analysis of the dye desorbed solution has been done. And the solar cell parameters such as short-circuit current density, open circuit voltage, fill factor, efficiency, have been calculated using the current density-voltage characteristics.