Surface modification of TiO2 photoanode in dye-sensitized solar cells using reduced graphene oxide: A computational and experimental study

Abstract

This study investigated the modification of TiO₂ photoanodes using reduced graphene oxide (rGO) to enhance electron transport channels and prevent recombination processes, thereby improving the photovoltaic performance. Through the ultraviolet (UV)-assisted photoreduction of GO on TiO₂ coated on a fluoride tin oxide substrate (FTO|TiO₂), we demonstrated the successful integration of rGO. This was evidenced by the increased Csp² content observed during X-ray photoelectron spectroscopy and reduced photogenerated electron–hole recombination observed during photoluminescence spectroscopy. The incorporation of rGO significantly improved the photocurrent density and power conversion efficiency (PCE). A 12 % increase was observed in the PCE, which reached 8.5 % when the UV irradiation time was optimized from 10 to 15 min compared with the 7.57 % in the standard cell (rGO-0 min). Electrochemical impedance spectroscopy confirmed that the optimized rGO content enhanced the electron lifetime and recombination resistance, attributable to the high conductivity and large specific surface area of rGO. DFT simulation further elucidated how improved charge separation and transport mechanisms of TiO₂–rGO heterojunction. This study highlights the potential of TiO₂–rGO materials as promising electrodes for improving the efficiency, capacity, and stability of dye-sensitized solar cells.