Betalain Pigments as Natural Photosensitizers for Dye-Sensitized Solar Cells: The Effect of Dye pH on the Photoelectric Parameters

Dye-sensitized solar cells (DSSC) were fabricated using red Bougainvillea glabra flower dye extracts as natural dye sensitizers at three dye pH values of 1.23, 3.0 and 5.7. Water was used as dye extracting solvent. Dye-sensitized solar cells (DSSCs) from dye extract of pH 3.0 had the highest photocurrent density J of 3.72 mA/cm² and fill factor FF of 0.59. While the DSSCs from dye sensitizer pHs of 1.23 and 5.7 had Jsc of 1.13 mA/cm² and 2.27 mA/cm², and fill factors of 0.43 and 0.61 respectively. The maximum powers P_max of the DSSCs were 0.50, 1.64 and 0.94 mW/cm² for dye sensitizer pH of 1.23, 3.0 and 5.7 respectively.