Green Synthesis of TiO2 Nanoparticles via Graphene Oxide-Doped Malabar Spinach Leaf Extract for Perovskite Solar Cells

This study investigates a green synthesis route for titanium dioxide (TiO2) nanoparticles (NPs) using Malabar spinach (Basella rubra) leaf extract, with graphene oxide (GO) as a dopant, for application as an electron transport layer in perovskite solar cells (PSCs). The synthesized TiO2 NPs were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (FESEM/EDX). XRD results confirmed the presence of a pure anatase phase with a smaller crystallite size than that of commercial TiO2, while EDX analysis verified the successful synthesis through elemental analysis. FESEM imaging revealed a mixture of rugged and uniformly distributed nanoparticles. Optical studies showed a reduced bandgap energy (3.0400 eV) compared to commercial TiO2 (3.2000 eV), indicating improved light absorption potential. The integration of GO suggestively enhanced photovoltaic performance, with the highest power conversion efficiency (0.2467%) observed in the sample synthesized using distilled water, leaf extract, and GO—an order of magnitude higher than commercial TiO2 (0.0259%). However, performance varied notably with different synthesis media, suggesting that solvent-specific interactions play a critical role in determining device efficiency. These findings demonstrate the viability of eco-friendly synthesis in developing functional nanomaterials and highlight the synergistic benefits of combining plant-based reductants and GO doping. The approach offers a promising pathway toward more sustainable and cost-effective PSC technologies; however, optimizing plant extract composition and nanoparticle morphology remains essential.