Vertically Aligned ZnO/InxSy Core–Shell Nanorods for High Efficient Dye-Sensitized Solar Cells

Abstract

Innovative vertically aligned ZnO / In x S y nanorod (NR) electrodes were prepared by successive ion layer adsorption and reaction (SILAR) technique. The In x S y shell layer was deposited on top of ZnO NR electrodes of two different lengths, ~1.6 μm and ~3.2 μm. Two sulfur contents on the In x S y shell layer with different layer thicknesses were analyzed. These electrodes were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), Energy-dispersive x-ray spectroscopy (EDS), Infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) and then applied in dye-sensitized solar cells (DSC). Power conversion efficiency of 2.32% was observed when a low-sulfur content In x S y shell layer was applied in comparison to the stoichiometric In 2 S 3 shell layer (0.21%) or the bare ZnO NRs (0.87%). In the case of low sulfur content, a shell layer of In ( OH )x S y or/and In ( OH )3 is formed as observed by the presence of – OH observed by FTIR analyses. The presence of higher amounts of hydroxide groups modifies the bandgap and work function of the In x S y shell and facilitates dye adsorption, increasing the final solar cell performance.