Natural pigment-based dye-sensitized solar cells utilizing Caulerpa racemose and Gymnogongrus flabelliformis as photosensitizers

This research examines natural dyes' chemical and physical characteristics for potential use in dye-sensitized solar cells (DSSCs). Chlorophyll pigments were extracted from two macroalgae species, Caulerpa racemosa and Gymnogongrus flabelliformis, and analyzed using absorbance spectroscopy, band gap energy calculations, and dye-sensitized solar cell performance evaluation. Fourier Transform Infrared (FTIR) characterisation was used to identify the pigments contained in the dye. The absorbance spectra of chlorophyll pigments extracted from both macroalgae species showed broad peaks at 400–800 nm wavelengths, with Gymnogongrus flabelliformis showing the highest absorbance peak at 403 nm. The redox potential analysis for both macroalgae species showed energy gaps (HOMO/LUMO) of 1.3 eV, 1.4 eV, 2.3 eV, and 2.4 eV, respectively, indicating that these natural dyes are suitable for use in DSSC applications. DSSC devices were fabricated using components such as liquid electrolyte, mesoporous titanium dioxide (TiO₂) photoelectrode, reduced graphene oxide (rGO) as counter electrode, and ITO glass as conductive substrate. Meanwhile, to evaluate how well the photovoltaic system worked, we looked at short-circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and overall photoelectric conversion efficiency (η). The results showed that the highest performance for Gymnogongrus flabelliformis was Jsc 0.041 mA/cm², Voc 0.28 V, FF 0.239, and η 0.020%, while the highest performance of Caulerpa racemosa was Jsc 0.023 mA/cm², Voc 0.46 V, FF 0.244, and η 0.019%. These findings indicate the potential for using and developing natural dyes derived from these two macroalgae species in DSSC technology. This research offers insight into the feasibility of marine-derived pigments as a sustainable and environmentally friendly alternative for photovoltaic applications.