Preliminary studies on high potential narrow-bandgap Parkia biglobosa pod husk natural dye extracts for high-performance DSSCs

The urgent global transition away from fossil fuels, driven by climate change mitigation, rising energy demands, and exponential growth of high-energy-consuming AI technology, calls for every available sustainable renewable energy solution. DSSCs emerge as promising photovoltaics due to their cost-effectiveness, efficiency in low-light conditions, versatility, and aesthetic appeal. A crucial avenue for enhancing DSSC sustainability lies in utilizing natural dyes as sensitizers. This study explores novel natural dye extracts from the pod husk of Parkia biglobosa, employing seven different solvents to investigate their photovoltaic potential. Some extracts exhibit exceptional light absorbance with band gaps ranging 1.82-2.85 eV—comparable to the high-performing synthetic N719 dye (1.75 eV). These performances surpass typical natural dyes with band gaps ≥2.0 eV. Photovoltaic performance assessments yielded efficiencies between 0.07-0.19%, within the reported range of natural dye DSSCs (0.05-4.2%; usually of high purity or combinations), though significantly lower than N719 (6.22%). Photoanode thickness reduction from 8 to 5 μm enhanced efficiencies to 0.09-0.24% (compared to 4.20% for N719), yet fell below anticipated values based on strong optical absorption. Subsequent characterizations—TG-DTA, IPCE, PL, EIS, FT-IR, and CV—identified two primary limiting factors: high series and ion diffusion resistances, attributed to inefficient band alignments with TiO₂ and the I₃⁻/I⁻ electrolyte, and dye degradation. Optimizing DSSC architecture through appropriate semiconductor materials and redox electrolytes could significantly improve these natural dyes performances. This work advances the potential for cost-effective, eco-friendly, high-performance DSSCs and contributes to groundwork for future advancements in sustainable solar energy.