Synergistic impact of Au/rGO decoration on vertically aligned TiO2 nanorod arrays for advanced plasmonic dye-sensitized solar cells

In the pursuit of improving the performance of dye-sensitized solar cells (DSSCs), improving surface area, electrical conductivity and efficient charge separation has been a crucial factor. This study investigates the integration of gold (Au) plasmonics and reduced graphene oxide (rGO) into TiO₂ nanorods (NRs) to advance DSSC performance. A nanohybrid photoanode comprising rutile phase TiO₂ NRs decorated with both rGO and Au was synthesized via hydrothermal method followed by UV irradiation. XRD verified the development of tetragonal rutile TiO₂ nanorods, while Raman and X-ray photoelectron spectroscopy (XPS) evidenced strong interactions among TiO₂, rGO and Au, promoting effective charge carrier transfer and lowered recombination rate. SEM assisted elemental analysis inferred the successful growth of one dimensional TiO₂ nanorods with an average length of 5.20 μm and 194 nm diameter and confirmed the effective decoration of nanorods with rGO and Au. UV–Visible spectra suggests that after Au/rGO decoration, the absorption edge shifts towards the visible area, the bandgap narrows and the visible light response is amplified. Then, the carrier transport properties and the performance of the DSSCs using decorated one-dimensional titanium dioxide nanorods as photoanodes, N719 sensitizer, liquid state electrolyte and Pt counter electrode have been examined utilizing current density-voltage plots attained at the treatment of 100 mW/cm². In comparison to pure TiO₂ NR photoanode, the decoration of Au/rGO onto TiO₂ NRs increased the photocurrent generation [J_sc = 18.22 mA/cm²], photoconversion efficiency [η = 6.74 %] and lowered the charge transfer resistance [R_ct = 8.50 Ω] at the Au/rGO@TiO₂/dye/electrolyte interface. The electrochemical behaviour of the fabricated device has also been analysed using electrochemical impedance spectroscopy and the lifetime of the injected electrons in the nanohybrid photoanode, assessed from the Bode phase plot was found to be 25.23 ms. Thus, the incorporation of rGO and Au enhances the electrical conductivity and plasmonic effects, respectively, leading to superior photovoltaic performance and this innovative approach highlights the potential for enhancing the conversion efficiency of DSSCs by leveraging the synergistic effects of advanced nanomaterials, thereby paving the path for the progress of high performance, efficient solar energy conversion devices.