Sustainable Dye-Sensitized Solar Cells Enhanced with CdS and Natural P. pterocarpum Dye for Dual Energy and Low-Light Sensing: The Synergistic Role of ZnO Nanorods and Natural Dyes

This study presents a novel and sustainable approach to dye-sensitized solar cell (DSSC) design by integrating a natural dye extracted from Peltophorum pterocarpum with CdS co-sensitization and ZnO nanorod-modified TiO₂ photoelectrodes. The fabricated DSSCs were enhanced through the integration of ZnO nanorods on TiO₂ photoelectrodes and further modified with CdS co-sensitization to boost their photovoltaic and photodetection capabilities. The devices were evaluated under a broad range of light intensities (100 to 0.01 mW/cm²), revealing dual functionality: efficient photovoltaic operation under standard illumination and superior sensitivity under ultra-low light. Under standard illumination, the highest efficiency (8.15%) was achieved with N719 dye and ZnO/TiO₂ electrodes. However, the P. pterocarpum-based cells also exhibited competitive performance, reaching 6.92% with CdS and ZnO enhancement. Remarkably, under ultra-low light (0.01 mW/cm²), the natural dye-based DSSCs demonstrated power conversion efficiencies exceeding 18%, rivaling commercial dye systems. These results highlight the synergistic role of ZnO nanorods and CdS in enhancing charge transport and light absorption, while also showcasing the viability of natural dyes for eco-friendly, low-cost optoelectronic applications. This study is among the first to demonstrate the synergistic integration of P. pterocarpum natural dye, CdS co-sensitization, and ZnO nanorods in DSSCs and in this research, sustainable natural dye utilization with structural nanomaterial engineering is uniquely bridged to develop DSSCs capable of dual functionality under both standard and ultra-low light conditions.