Characterization of Ochre Mineral Dye for Potential Application as a Photosensitizer in Dye-Sensitized Solar Cells

The search for low-cost, environmentally friendly, and sustainable photosensitizers remains key to improving the sustainability of dye-sensitized solar cells (DSSCs). In this work, ochre, a naturally occurring mineral pigment, was extracted and characterized to evaluate its suitability as a photosensitizing material for DSSC applications. The optical, structural, elemental, and functional properties of the dye were investigated using UV–Visible spectroscopy, X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD), respectively. UV-Vis analysis revealed strong absorption in the ultraviolet region with an absorption edge around ۳۰۰ nm, corresponding to an optical bandgap of approximately ۴.۱ eV, indicating limited visible-light harvesting capability. XRF results confirmed that the dye is dominated by silica and iron oxide phases, with hematite (Fe₂O₃) identified as a key constituent alongside aluminosilicate and minor transition-metal components. FTIR spectra showed abundant hydroxyl and metal-oxygen functional groups, suggesting favorable surface chemistry for adsorption and interfacial charge transfer on metal-oxide photoanodes. XRD analysis revealed a partially crystalline structure consistent with Fe₂O₃, confirming the mineralogical stability of the extracted dye. Although the wide bandgap of ochre limits its performance as a standalone sensitizer, its structural robustness, surface hydroxylation, and ultraviolet absorption characteristics highlight its potential role as a co-sensitizer in DSSCs. The findings provide experimental insight into the feasibility of utilizing mineral-based natural dyes as stable and sustainable components in next-generation DSSCs.

کلیدواژه ها:

Dye-sensitized solar cells ، Mineral-based photosensitizer ، Ochre (Fe₂O₃-rich pigment) ، Co-sensitization strategy ، Sustainable solar materials