Green synthesis and characterization of graphene/SnO₂ nanocomposite photoanodes for enhanced DSSC performance

Abstract

Dye-sensitized solar cells (DSSCs) offer a compelling alternative to conventional silicon-based solar cells due to their cost-effectiveness, flexibility, and relatively high efficiency. However, their performance is currently hindered by the photoanode material, typically titanium dioxide (TiO₂). This study aims to develop a green synthesis method for graphene/tin dioxide nanocomposites (G/SnO₂ NCs) using Bryophyllum pinnatum extract for DSSC applications. SnO₂ nanoparticles (SnO2 NPs) were synthesized using a green method with Bryophyllum pinnatum extract and integrated with biomass-derived graphene to fabricate G/SnO₂ NCs for DSSC applications. Characterization techniques, including UV-Vis spectroscopy, XRD, FTIR, SEM, and EDX, were employed to analyze the optical, structural, functional, morphological, and elemental compositional properties of graphene, SnO₂, and the G/SnO₂ NCs. The photoanode thin films were deposited using the doctor blade technique, and their electrical properties were evaluated using four-point probe measurements. Results demonstrate that the G/SnO₂ NCs exhibit significantly enhanced electrical conductivity (0.148 S/m) compared to pristine SnO₂ (0.098 S/m) and graphene (0.122 S/m), indicating improved charge transport properties within the composite material. This enhancement is attributed to the synergistic effect of the high electron mobility of SnO₂ and the excellent conductivity of graphene. Furthermore, the G/SnO₂ NCs exhibit lower sheet resistance (549.48 Ω), further suggesting its potential for efficient charge collection in DSSC applications. The graphene/SnO₂ nanocomposites exhibited enhanced electrical conductivity, improved charge transport properties, and lower sheet resistance compared to pristine SnO₂ and graphene. These findings suggest that the synergistic combination of SnO₂ and graphene offers a promising pathway to improved efficiency in DSSC applications. This research contributes to the development of sustainable and cost-effective solar energy solutions, offering a promising alternative to conventional silicon-based solar cells.