Investigation of dye-sensitized solar cell performance based on vertically aligned TiO2 nanowire photoanode

Abstract

In this work, we present our results related to the development of Dye-Sensitized Solar Cells (DSSCs) based on vertically aligned TiO2-nanowire (NW) and Ag nanoparticle (NP) assisted vertically aligned TiO2-NW (TAT) photoanode fabricated by the glancing angle deposition (GLAD) technique on fluorine doped thin oxide (FTO) substrates. The scanning electron microscopy (SEM) analysis reveals that the Ag-NP assisted vertically aligned TiO2-NW photoanode was successfully deposited on FTO substrates. The average length and diameter of the NW have been measured to be ~ 350 nm and ~ 90 - 100 nm, respectively. Moreover, transmission electron microscopy (TEM) and X-ray diffraction (XRD) manifest the presence of small crystals of TiO2 and Ag. Further, the absorption spectrum analysis reveals that the incorporation of Ag-NP in TiO2-NW increases absorption in the visible region, but decreases the efficiency of the cell after the incorporation of the nanoparticle. The calculated bandgap of the annealed Ag-NP (30 nm) assisted TiO2-NW (TAT@30nm) sample from the photoluminescence (PL) graph is ~ 3.12 eV. Finally, it is observed that the TiO2-NW based DSSC device shows better performance in terms of photo conversion efficiency (PCE) compared to the TAT@30nm photoanode based device, with an efficiency of ~0.61 % from the former and ~ 0.24 % from the latter. This reduction in the efficiency of TAT@30nm based devices is due to the larger size of Ag-NP, in which the nanoaprticle acts as an electron sink and acts as a blocking layer.