Evaluation of the Solvent Effects and Photovoltaic Performance of Chlorella vulgaris Chlorophyll as a Natural Sensitizer in Dye-Sensitized Solar Cells

In response to the escalating global fuel crisis, this study investigates the potential of using chlorophyll from the microalga Chlorella vulgaris as a natural, abundant, and sustainable photosensitizer for Dye-Sensitized Solar Cells (DSSCs), aiming to provide an environmentally benign alternative to conventional ruthenium-based dyes. The study investigates chlorophyll extracted from the highly abundant microalga Chlorella vulgaris as a green, cost-effective alternative to the rare and expensive ruthenium-based dyes traditionally used. The study began with a rigorous comparison of extraction solvents, determining that acetone yields a significantly higher concentration of chlorophyll (28.76 µg/L) than methanol, establishing it as the superior medium for pigment harvesting. When this chlorophyll extract was integrated as a photosensitizer in a TiO₂-based solar cell, it achieved a power conversion efficiency of 0.0115%. While modest, this represents a more than 2,000-fold performance increase over the dye-free control cell, unequivocally demonstrating the pigment's photoelectric activity. However, the results reveal a critical limitation: the inherent molecular structure of chlorophyll, while perfected for photosynthesis, inhibits robust electronic binding to the TiO₂ semiconductor surface, leading to inefficient charge injection and low overall performance. This study provides a crucial insight for the field, concluding that while Chlorella vulgaris is an excellent and sustainable source, future success for chlorophyll-based DSSCs will depend on molecular engineering strategies to enhance the crucial dye–semiconductor interface.