In this work, we report the synthesis of TiO2 photoelectrodes sensitized with different natural organic dyes extracted (using methanol) from spinach, raspberry and passion fruit for their application ...in Dye-Sensitized Solar Cells (DSSC). The effects of Lead Sulfide (PbS) NanoParticles (NPs) doping on the sensitized TiO2 photoelectrodes photovoltaic performance were mainly studied. Good absorption in the visible range (400–700 nm) was observed for natural dyes extracted from spinach and raspberry, observing characteristic peaks associated with chlorophylls, β-carotenes and phycoerythrin pigments. On the other hand, natural dye synthesized from passion fruit showed a poor absorption in this range concerning the previous mentioned sources. Cells using spinach and raspberry based dyes generally showed good Fill Factors (FF) higher than 55%, observing depreciable or negative influence of the PbS doping. Open-Circuit voltages (Voc), Short-Circuit current densities (Jsc) and Power Conversion Efficiencies (PCE) in the range of 0.35–0.55 V, 0.01–0.12 mA/cm2 and 0.002–0.03 % were respectively estimated.
•Natural organic dyes were synthesized from spinach, raspberry and passion fruit.•Spinach and raspberry dyes showed considerable optical absorption in visible range.•DSSCs presented high fill factors (>55 %) by using spinach and raspberry dyes.•PbS-NPs doping depreciably or negatively affected the photovoltaic performance.•Results suggest possible incompatibilities between PbS-NPs and natural dyes.
Azo dyes, including Tartrazine, Sunset Yellow, and Carmoisine, are added to foods to provide color, but they have no value with regard to nutrition, food preservation, or health benefits. Because of ...their availability, affordability, stability, and low cost, and because they provide intense coloration to the product without contributing unwanted flavors, the food industry often prefers to use synthetic azo dyes rather than natural colorants. Food dyes have been tested by regulatory agencies responsible for guaranteeing consumer safety. Nevertheless, the safety of these colorants remains controversial; they have been associated with adverse effects, particularly due to the reduction and cleavage of the azo bond. Here, we review the features, classification, regulation, toxicity, and alternatives to the use of azo dyes in food.
•The availability, affordability, stability and safety of azo dyes make them desirable for food use.•Tartrazine, Sunset Yellow or Carmoisine are the most widely used azo dyes due to their coloring capacity.•The safety of these artificial colorants is controversial due to possible adverse and toxic effects.•Further research on these dyes is needed to provide consistent data, alternatives to their use and safety.
Herein, we investigate the effect of various solvents on the extraction of natural dyes from two different fruit skins, namely Annona atemoya (Atemoya) and Physalis peruviana (Physalis), as ...photosensitizers for dye-sensitized solar cells (DSSCs). The functional groups of the extracted dye pigmentation were confirmed using Fourier-transform infrared spectroscopy (FTIR) to verify the presence of anthocyanin radicals. To fabricate the DSSCs, semiconducting TiO2 nanoparticles were deposited on FTO glass as a photoanode (using the spin-coating method), and platinum was also deposited on FTO glass as a photocathode (using the drop-casting method). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were performed to verify the surface roughness and morphologies of the TiO2 photoanode and Pt photocathode. The photoelectric performance results of the fabricated DSSCs were examined and revealed the influence of various solvents on the extraction of Annona atemoya and Physalis peruviana dyes. The extraction of Annona atemoya and Physalis peruviana dyes in methanol solvent showed higher energy conversion efficiency of 2.02 % and 0.31 %, respectively, compared to other solvent extractions. In general, this work demonstrates that constructing solar cells from natural dyes at a reduced cost is a viable and sustainable alternative to traditional silicon cells.
•Annona atemoya and Physalis peruviana fruits as used novel light harvesters in DSSCs.•Influence of different solvent extraction of pigments in DSCCs performance.•Improvement of extraction of natural pigments in methanol as solvent.•Annona atemoya fruit peel containing to be rich in Acetogenins.•Physalis peruviana fruits peel containing to be rich in oleanolic acid and betulin.
Although efficiency of Dye Sensitized Solar Cell (DSSC) is still below the performance level of the market dominance silicon solar cells, in the last two decades DSSC has gathered sufficient ...interests because of the simplicity in device fabrication and low material cost, and therefore, DSSC is providing a possibility of solar cells production at a low entry cost. This review presents the research progress made in the implementation of natural pigments in DSSC. These pigments function as dye sensitizers and they play a major role in DSSC by absorbing light, and supplying electrons to the semiconductor matrixes in the cell. The common choices of dyes are the metal complexes, organic and/or natural dyes. A better efficiency with higher durability is observed for DSSC using metal complexes and organic dyes, however, the process of synthesizing these dyes is laborious, costly, and involves the use of toxic materials. As an alternative, natural pigments (dyes) found in plants such as anthocyanin, carotenoid, aurone, chlorophyll, tannin, betalain and many others are accepted as dyes in DSSCs. These natural pigments are easily obtained from fruits, flowers, leaves, seeds, barks and various parts of plants. Despite the limited performance of natural dyes, the prevailing advantages of natural dyes include high absorption coefficients, high light harvesting efficiency, low cost extraction and low toxicity. This review provides insight into the usage of the various natural pigments as sensitizers, the techniques to improve the pigments performance in DSSC, an outlook on the developmental work on the application of natural pigments in DSSC and their limitation. Additionally, the paper discusses the overall operation principle and the recent developments of each component of DSSC, as well as, comparing the material cost between natural dye and synthetic dye DSSC.
•Natural pigments have a promising future as sensitizers in DSSCs.•Anthocyanin, carotenoid, aurone, chlorophyll, tannin and betalain are among the natural pigments used as sensitizers.•Low-cost extraction, vast availability and eco-friendliness are major attractions of natural pigments.•The total fabrication cost for DSSC sensitized with chlorophyll is less than ~€ 2 per Watt peak.
Due to relatively wide range of hues and great biocompatibility, natural dyes are now frequently employed in replacing synthetic dyes in many areas with high safety requirements. Natural dyes, ...however, are often ruined or faded in the process of storage and application because of their unique chemical structure. In this paper, packaging ink microcapsules with high stability and biocompatibility was prepared by in situ polymerization with polymethyl methacrylate (PMMA) as wall material, and gardenia blue (GB) natural dye as core material. The effects of the preparation parameters, such as dosages of the core material, emulsifier, and initiator on the morphology, structure, and stability of GB-PMMA microcapsules were characterized by means of scanner electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the encapsulation efficiency of GB-PMMA microcapsules can reach up to 84.8%. GB-PMMA microcapsules exhibit smooth and dense spherical appearance. Thermal stability of natural dye GB was improved by nearly 40% after being microencapsulated. Moreover, the adhesion and acid/alkali resistance grade of packaging ink containing GB-PMMA microcapsules are all higher than or equal to 3 level. Therefore, the GB-PMMA microcapsule samples prepared in this paper is expected to be used for printing ink of food packaging owing to their high stability and biocompatibility.
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•Chrysanthemum flowers as new light collectors used in DSSCs.•Flowers of Chrysanthemum are noted to be rich in anthocyanins.•Influence of various types of flowers on the performance ...of DSCCs was analyzed.•Chrysanthemum Violet has higher conversion efficiency (η) than other flowers.
In this work, natural dyes from three different species of the same flower family (Chrysanthemum), which containing anthocyanin were extracted and properly prepared to be used as photosensitizers in DSSCs construction. The cells were fabricated with titanium dioxide nanoparticles (TiO2) for the photoanodes, whereas platinum electrodes were used for the photocathodes. To understand the behavior of light absorption in addition to the coloring components present in the dyes and the molecular functional groups present in the samples, the UV–Vis absorption spectroscopy and FTIR spectroscopy were used respectively. The performance and efficiency of solar cells were evaluated to establish the photovoltaic criteria for each DSSC built. Through electrochemical characterizations, it was possible to notice that the highest photovoltaic conversion efficiency was obtained with the Chrysanthemum Violet (CV) cell, with efficiency (η) of 1.348%, compared to 1.229% and 0.485% for the Chrysanthemum Green (CG) and Chrysanthemum Blue (CB) cells, respectively. The CV cell also has the highest open circuit voltage (VOC) at 0.58 V. The results corroborate to present the organic solar cells as a viable option for the electric energy generation.
Recently, there has been an increasing interest towards the fabrication/finishing of bioactive materials using natural plant extracts, which can achieve a wide range of functional properties and ...environmental benefits. This study presents an environmentally benign bioactive finishing of wool fabric via the use of unexplored tannin-rich waste/fallen leaves extract of Chinese tallow/Sapium sebiferum L. through simple adsorption technique. Simple aqueous extraction followed by the evaluations of build-up properties on wool fabric using Chinese Tallow (CT) leaves extract were studied in due course of this study. Optimization of extraction and dyeing variables/conditions such as pH, temperature, CT concentration, and time were conducted using UV–Visible and reflectance spectral method. The nature of functional groups of the extracted dye were investigated through FT-IR spectral analysis with further in depth thermal analyses using TG and DSC measurements. Additionally, the extracted dye was subjected to quantitative analytical tests to check the relative amounts of total phenolics and flavonoid with respect to gallic acid and catechin equivalents, respectively. Build-up properties and fastness characteristics were studied in the presence and absence of mordants (two metal and one biomordant) under corresponding ISO standards. Results showed that wool fabric treated with CT leaves extract exhibit excellent antioxidant activity, good UV protection and high antibacterial activities against E. coli and S. aureus. The use of biomordant to alter the functional properties provide an eco-friendly method for wool finishing. In general, the treated wool fabric in this work has shown a promising future for the preparation of health and hygiene-related textile materials.
•An environmentally friendly benign cleaner production procedure has been presented.•Waste/fallen leaves of Sapium sebiferum L. were used for natural dye production.•Extracted dye was characterized by UV–visible and FT-IR analysis.•Potential antibacterial and antioxidant wool fabrics were produced.•Finished wool fabric possesses excellent UV protective properties.
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•The co-sensitization approach employed to achieve panchromatic light-harvesting.•The treated cocktail with multi-anchor groups increased electron transfer channels.•Homogeneous ...dispersion of the pigment molecules improved dye adsorption efficiency.•The acidified cocktail enhanced the DSSC short current and efficiency.•Significant improvement in NDSSC stability was achieved using co-sensitization.
Co-sensitization is an effective strategy to achieve panchromatic light-harvesting and to enhance dye-sensitized solar cell performance. In this work, the potential of the extracted natural dyes from Malva verticillata and Syzygium cumini was evaluated as mono and co-sensitizers in DSSCs. The UV–vis absorption spectra revealed that the combination of studied dyes had a high molar extinction coefficient and cumulative absorption properties in a way that its absorption spectra overlapped the spectral domain where the original sensitizers lacked light-harvesting. Moreover, all investigated dyes were characterized using circular dichroism, dynamic light scattering, zeta potential, cyclic voltammetry, and Fourier-transform infrared spectroscopy. The results of zeta potential analysis showed that the pigment aggregation and their colloidal stability, which has implications for the pigment adsorption process on TiO2 nanoparticles, were effectively controlled by varying the pH of the dye extract. Based on the CV results, the studied dyes indicated excellent redox stability and sufficient thermodynamic driving force for efficient electron injection. Based on the photovoltaic results, the acidified cocktail-DSSC had the highest Isc and η of 3.15 mA and 1.84 %, respectively. This superiority could be ascribed to the panchromatic light-harvesting, the excellent optical activity, and the appropriate energy levels of the acidified cocktail. Moreover, the loading of acidified cocktail dyes on the TiO2 surface was enhanced due to their homogeneous dispersion, less steric hindrances, and multi-anchor groups attached to the semiconductor surface. Based on the stability results, the treated cocktail-DSSC retained about 52.51 % of its as-fabricated efficiency after seven days while NDSSCs sensitized with acidified Syzygium cumini, Malva verticillata, Syzygium cumini, and cocktail retained about 26.24 %, 14.80 %, 16.35 %, and 15.25 %, respectively.
