Tuning interfacial charge dynamics in 2D SnO2–MWCNT composite photoanodes for dye-sensitized solar cells

This paper presents a low-temperature, facile, and cost-effective wet chemical synthesis of two-dimensional (2D) tin oxide (SnO2)–multi-walled carbon nanotube (MWCNT) composites for efficient dye-sensitized solar cells (DSSCs). Incorporating varying concentrations of MWCNTs into 2D SnO2 nanosheets significantly enhanced the overall photovoltaic performance by improving charge separation and suppressing electron–hole recombination. The 2D SnO2–MWCNT composites exhibited remarkable photoluminescence quenching and increased UV-vis absorbance, indicating efficient photoinduced charge transfer. The optimized 2D SnO2–MWCNT composite photoanode achieved a power conversion efficiency (PCE) of 3.84%, which was ~ 3.5 times higher than that of the pristine SnO2 nanosheets (1.83%). This PCE improvement was attributed to an increase in the short-circuit current density (Jsc) and the fill factor (FF). Additionally, electrochemical impedance spectroscopy (EIS) measurements confirmed the reduced charge transport resistance, increased electron diffusion length, enhanced charge collection efficiency, and enhanced electron mobility of the 2D SnO2–MWCNT composites. This improved photovoltaic performance is primarily attributed to the incorporation of MWCNTs, which provide efficient electron-conducting pathways that mitigate recombination. These results highlight the potential of 2D SnO2–MWCNT composites as efficient photoanodes for DSSCs, providing valuable insights into the interfacial charge dynamics of next-generation optoelectronic devices.