Fast and green process to obtain astaxanthin-rich extracts from shrimp shell waste for dye sensitized solar cells

Aiming to address the critical need for renewable energy, this study explores the potential of astaxanthin-rich extracts from shrimp waste as natural sensitizers for dye-sensitized solar cells (DSSCs) using an eco-friendly and economically viable process. Photoconversion efficiencies (PCE) of astaxanthin-based DSSCs were evaluated through I-V measurements while charge transfer resistances (R CT ) were assessed by electrochemical impedance spectroscopy. The sensitizer preparation involved extraction of astaxanthin from waste shrimp ( Aristaeomorpha foliacea ) cephalothoraxes, which were desiccated, finely milled and treated with ethyl acetate, to obtain a crude extract very rich in astaxanthin mainly present in esterified forms. The extraction process was fast and avoided extreme experimental conditions in terms of energy consumption, ultra-vacuum, high temperatures and use of toxic solvents. Direct application of the crude extract as sensitizer for DSSCs resulted in low PCE (0.09%) and high R CT , due to the limited ability of esterified astaxanthin to interact with the TiO₂ layer. This limitation was overcome through saponification of the extract with methanolic NaOH, leading to free astaxanthin with high recovery yield and limited degradation. The saponified extract showed lower R CT and higher PCE (0.30%). These results highlight the promising potential of suitably processed shrimp waste as a source of sensitizers for DSSCs. • Shrimp waste used as a source of astaxanthin for DSSC (dye sensitized solar cell) • Fast and green process to extract and de-esterificate the astaxanthin • Sustainable and economical approach for the production of clean energy