Performance of dye-sensitized solar cells extracted dye from wood apple leaves

Abstract

In this work, wood apple leaves dye has been extracted, characterized, and examined as a potential photosensitizer for dye-sensitized solar cells (DSSCs). The dye was extracted in an ethanolic medium from the fresh wood apple leaves and characterized using thin-layer chromatography (TLC), ultraviolet-visible (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. The current density-voltage (J-V) characteristics measurements were performed on the two assembled DSSCs for 1- 22 days using fresh and seven days old extracted dye. The characterization results revealed that the extracted dye mainly contains the compound of carotenoids (neoxanthin), chlorophyll-a, chlorophyll-b, and their derivative (pheophytin) with various functional groups. The J-V characteristics of DSSCs indicate that an open-circuit voltage and short circuit current density radically decrease with increasing time, thus degrading the efficiency of cells. A degraded DSSCs suffered from high defect recombination may be induced by Mg ions migrating from chlorophyll dye into DSSC. Therefore, the extracted dye may be used for energy harvesting from the wood apple leaves.

Optical absorption and photoluminescence properties of Cucurbita maxima dye adsorption on TiO2 nanoparticles

“…Where A absorbance, ε is the molar absorption coefficient, C is the molar concentration, and l is the optical path length [21]. Broadening of the bands in the range 635-674 nm was observed for higher concentrations, indicating chlorophyll-chlorophyll interactions, as has been observed in similar studies [19]. The bandgap energy of the material in the solid-state form is the difference between the conduction and valence band energies.…”

“…A peak at approximately 333 nm represents the existence of C=O or C=C functional groups that are responsible for the n-π * electronic transition that can initiate electrical circuits in DSSCs and can facilitate their adsorption onto TiO 2 surfaces [17,18]. Two prominent absorption bands in the blue visible (450-500 nm) and red visible (635-674 nm) ranges have been observed in other related studies and are attributed to the presence of chlorophyll b and chlorophyll a [19,20]. From figure 1(a), it is observed that the absorbance increases with dye concentration and can follow the Beer-Lambert Law represented by equation (1).…”

“…The optical bandgap of the TiO 2 sample was estimated from the Tauc plot, as shown in the inset of figure 3(b), that is, a plot of (αhν) 2 against hν for the direct bandgap material and calculated from the linear fit as 3.33 eV. The absorbance of Cucurbita adsorbed on TiO 2 nanoparticles is shown in figure 3(c), which shows three distinct regions, which correspond to the optical bands for TiO 2 in the Uv region: Cucurbita maxima in the blue visible (450-500 nm) and red visible (635-674 nm) ranges which imply the presence of chlorophyll b and chlorophyll a, respectively, that have been adsorbed on the TiO 2 nanoparticles [19,20]. The inset of figure 3(c) shows the enlarged region of the expected region where the adsorption of Cucurbita maxima dye on TiO 2 nanoparticles is expected.…”

“…The Tauc plot method is known to provide approximate values of the band gap because it assumes an ideal parabolic band structure and depends on the type of transition [27]. This method has been adopted to calculate the band gap for chlorophyll a and anthocyanin pigments in related studies with acceptable levels of accuracy [17,19,20,28,29]. The general molecular structure of chlorophyll is shown in figure 2(d).…”