Fabrication and Characterisation of Dye-Sensitised Solar Cells Using Natural Dyes Extracted from Nigerian Tropical Fruits

Background: Dye-sensitised solar cells offer a low-cost alternative to silicon photovoltaics, with natural plant-derived dyes as an environmentally benign sensitiser source. Systematic characterisation of Nigerian tropical fruit-derived dyes for DSSC applications remains a significant research gap. Aim: This study fabricated and characterised DSSCs sensitised with dyes extracted from three Nigerian tropical fruits: bitter kola, zobo hibiscus, and purple grape. Methods: Dye extraction, characterisation by UV-Vis spectroscopy, and TiO2 photoanode preparation were conducted following established DSSC fabrication protocols. Electrochemical impedance spectroscopy, current-voltage measurements, and incident photon-to-current efficiency were used to characterise cell performance under AM1.5G simulated illumination. Results: Bitter kola dye showed the highest light absorption in the 440 to 580 nm range and yielded the best cell efficiency of 3.8%. Zobo dye produced 2.9% efficiency and purple grape 2.1%. All cells outperformed reference cells using commercial synthetic dye N719 in the blue wavelength range but showed lower red response. Conclusion: Nigerian tropical fruit-derived dyes are viable sensitisers for cost-effective DSSC fabrication. Co-sensitisation strategies combining multiple dye extracts to extend spectral coverage warrant further investigation for efficiency enhancement. Keywords: dye-sensitised solar cell, natural dyes, tropical fruits, Nigeria, photovoltaic efficiency.