Preliminary studies on high potential narrow-bandgap <i>Parkia biglobosa</i> 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 <i>Parkia biglobosa</i>, 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.