Investigation of Optical Properties of Dye-Sensitised Solar Cell Prototypes Using Natural Nigerian Dyes

Dye-sensitised solar cells represent a low-cost alternative to conventional silicon photovoltaic cells for small-scale power generation in rural communities. Natural dyes extracted from Nigerian plant sources can serve as photosensitisers in these devices, offering biodegradable and locally available alternatives to synthetic ruthenium dyes. This study fabricates and characterises dye-sensitised solar cell prototypes sensitised with natural dyes extracted from bitter leaf, zobo hibiscus petals, and purple sweet potato sourced in Anambra State. Dye extracts are prepared in ethanol solvent and characterised by UV-Vis spectrophotometry to determine light harvesting efficiency across the solar spectrum. TiO2 photoanodes are sensitised by 24-hour dye immersion, and cells are assembled using iodine-iodide electrolyte and platinum-coated counter electrodes. Current-voltage characteristics are measured under AM1.5 simulated solar illumination. Results indicate open-circuit voltages of 0.42 to 0.56 V and short-circuit current densities of 0.8 to 2.3 mA per square centimetre. Zobo extract achieves the highest power conversion efficiency of 0.71 percent due to its broad absorption spectrum centred at 520 nm. The study provides a foundation for advancing natural dye solar cell research at Nigerian universities. Keywords: dye-sensitised solar cell, natural dye, zobo, photovoltaic, TiO2