Optimization of the Extraction Process of Natural Pigments from the Oenocarpus Genus and Analysis of Co-sensitization in Dye-Sensitized Solar Cells

Abstract In response to the global demand for clean energy, research on solar technologies has intensified. In Brazil, dye-sensitized solar cells (DSSCs) have emerged as a promising alternative due to their economic viability. However, the high cost of synthetic N719 dye, one of the most efficient sensitizers, remains a barrier to largescale application. This study aimed to reduce DSSC production costs by partially replacing N719 with natural dyes extracted from Oenocarpus fruits (patauá and bacaba). We hypothesized that combining these natural dyes could produce a synergistic effect by exploiting complementary absorption spectra, thereby maintaining device efficiency. The methodology involved selecting the most efficient semiconductor among Nb₂O₅, TiO₂, and Nb₂O₅/TiO₂ composites, and optimizing natural dye extraction using a Box–Behnken experimental design. Interactions between dyes were investigated through a simplex centroid design, which enabled modeling of mixture behavior. The results indicated additive interactions between the natural dyes, whereas binary mixtures of natural dyes with N719 exhibited antagonistic behavior, leading to reduced efficiency. Nevertheless, considering the nonlinear relationship between efficiency and the high cost of N719, combining natural and synthetic dyes may still be economically advantageous for specific applications. These findings provide valuable insights for advancing research on dye combinations in DSSCs.