Palmyrah Seed-Derived Activated Charcoal/TiO₂ Composites as a Counter Electrode for Dye-Sensitized Solar Cells

Platinum (Pt) is a widely used counter electrode (CE) material in dye-sensitized solar cells (DSSCs) due to its excellent catalytic properties. However, the steep cost limits its widespread adoption. This has spurred researchers to focus on carbon-based materials, which are abundant and economically viable alternatives. In this study, charcoal was derived from palmyrah seeds and activated by a simple thermal shock method involving rapid water immersion. This palmyrah seed-based activated charcoal (AC) was then combined with TiO₂ to create a novel composite paste, enhancing amalgamation between carbon particles and adhesion of the carbon particles on the FTO glass substrate. XPS analysis confirmed the successful formation of the palmyrah seed-derived charcoal. Raman spectroscopic analysis revealed that the palmyrah seed-based AC showcases a graphite nature, a trait retained even in the composite film formed with TiO₂. A DSSC was fabricated employing the as-prepared AC/TiO₂ composite as the CE, N719 dye-coated TiO₂ as the photoanode and an $I^{-}/I_3^{-}$ redox couple as the electrolyte. While the optimized AC/TiO₂ (80:20) composite CE annealed at 400 °C demonstrated a power conversion efficiency (PCE) of 4.85%, an encouraging result relative to the PCE of a commercial Pt CE (6.88%), the AC/TiO₂ composite offers a cost-effective and eco-friendly alternative, with potential for future optimization. Moreover, the device with the AC/TiO₂ composite CE displayed notable catalytic reduction of $I_3^{-}$ to Ι ^- and greatest stability compared to the DSSC fabricated with Pt CE.