Impact of solvents on the extraction and purification of vegetable dyes onto the efficiency for dye-sensitized solar cells

Abstract

Eight vegetable dyes extracted from flowers, fruits and leaves abundant in the wide biodiversity of the Andes region of South America were extracted with ethanol without purification to explore as vegetable photosensitizers in dye-sensitized solar cells (DSSCs). The absorbance spectra were measured by UV-visible spectroscopy and the photoelectrical performance of the DSSCs based on these dyes with a homemade solar simulator, constructed only for educational purposes under 1 sun of illumination. The open-circuit voltages (V oc) and the short-circuit photocurrent densities (J sc) varied from 0.39 to 0.48 V and from 0.04 to 0.56 mA cm −2 , and the power conversion efficiency (PCE) ranged from 0.01 to 0.18%. Particularly, the highest V oc and PCE values of the DSSCs sensitized by the ethanol extracts of Mortiño fruit (Vaccinium floribundum) and Jamaica flowers (Hibiscus sabdariffa) without purification were presumably associated with anthocyanin, the most effective component present in both vegetable photosensitizers. Hence, various components of the ethanol extracts obtained from these two vegetable dyes were purified by liquid-liquid extraction using different organic solvents of different polarity, namely petroleum ether, chloroform, ethyl acetate, n-butanol, and distilled water. Ethyl acetate resulted as the most favorable solvent for purification of ethanol extracts from Mortiño fruit and Jamaica flowers to use as vegetable photosensitizers in DSSCs. The PCE of the DSSC fabricated with the dye extracted in ethyl acetate from Mortiño fruit achieved 0.33%, with V oc of 0.520 V and J sc of 1.014 mA cm −2 , whereas the corresponding values obtained from the dye extracted from Jamaica flowers reached 0.22% with V oc of 0.541 V and J sc of 0.678 mA cm −2. Thus, the purification of vegetable dyes used as photosensitizer impacts the photoelectrochemical performance of DSSCs.

Performance Simulation of Ipomoea involucrata Dye Extracts for Dye Sensitized Solar Cells

“…Consequently, the results obtained using anthocyanins are lower or comparable to those reported in other studies: Rhuc/sumas fruits (1.5%) [25], Hibiscus sabdariffa (0.033%) [15], Brassica olercea (0.13%) [26]. The performance of the fabricated devices may be affected by the type of absorption between the anthocyanins and the TiO 2 pore structure [24]. It is assumed that the similarity in size between the pores and dye molecules results in more adsorption until the pores are filled with anthocyanins.…”

“…Consequently, the leaves purified extract exhibits a higher absorbance compared to the other extracts which can be linked to the presence of high concentration of anthocyanins in the extract which helps in the absorption of light. Also, the difference in the absorption spectra could be due to the different colours of the extracts [24]. The absorbance spectra obtained for the extracts indicate that the samples can be used as sensitizers in DSSCs application.…”

Recent Progress, Advancements, and Efficiency Improvement Techniques of Natural Plant Pigment‐Based Photosensitizers for Dye‐Sensitized Solar Cells

“…Cosensitizing pigments with a complementary absorption spectra increase the absorption band and are an attractive pathway to enhance the efficiency in DSSCs [124]. Ramirez-Perez et al [104] reported that the predominance of hydroxyl groups on the aromatic skeleton of anthocyanin gives rise to an intense blue color, while a red color is observed in methoxyl functional groups [104]. In brief, lawsone solar cells displayed better performance, showing average efficiencies of 0:311 ± 0:034%, compared to indigo solar cells showing efficiencies of 0:060 ± 0:004%.…”

Catalytic Behavior of Extended π-Conjugation in the Kinetics of Sensitizer-Mediator Interaction

“…Studies on making ecologically acceptable and stable DSSCs using natural dyes and NHC-based iron as sensitizers [8][9][10], copper and other transition metal-based mediators [11,12], and electrolytes based on gels and polymers [13][14][15][16][17] have been published. The steric, structural, and compositional effects of solvent on the efficiency of DSSC have also been investigated electrochemically [15,18].…”