Evaluation of absorbance for crude and purified natural dyes using Senna singueana, Bougainvillea glabra bracts, and Ximenia caffra on DSSC performance parameters

Abstract

ABSTRACT Natural dyes extracted from Senna singueana flowers and leaves, Ximenia caffra fruits and Bougainvillea glabra bracts were used as sensitizers to fabricate dye sensitized solar cells (DSSCs). The UV-Vis characterization of these species’ crude and purified natural dyes showed that Senna singueana leaves have broad broadband absorption, followed by Bougainvillea glabra bracts. The absorption intensity of Senna singueana leave and Bougainvillea glabra bract for crude and purified dyes was comparable, indicating their potential in DSSCs performance. The photoelectrochemical performance of the selected dyes used as a sensitizer in DSSCs indicated that Senna singueana leaves attained the highest open-circuit voltage (Voc) and short circuit current density (Jsc) of 471 mV and 4.32 mA/cm2 for crude dye, and 355 mV and 4.87 mA/cm2 for purified dye. In contrast, Bougainvillea glabra bract had 380 mV and 3.34 mA/cm2 for crude dye and 75 mV and 1.95 mA/cm2 for purified dye. The photo-to-electric conversion efficiency of the DSSCs based on Senna singueana leaves as sensitizers were 0.68% (crude) and 0.51% (purified) and that of Bougainvillea glabra bract were 0.45% (crude) and 0.04% (purified). To our best knowledge, this is the first time to report the highest efficiency for Senna singueana leave in DSSC. Various organic solvents were used for purification; however, the photoelectrochemical performance of those extracts demonstrated that crude dyes are more effective than purified dyes as sensitizers in DSSCs application.