Dye-sensitized solar cell (DSSC) provides credible alternative concept for inorganic solid-state photovoltaic devices. The conversion efficiency of DSSC is mainly based on the dye coated on the ...porous semiconductor TiO2 film. The use of natural dyes in solar cells is a promising development to this technology because it cuts down the high cost of noble metals and chemical synthesis. Therefore, this type of solar cell has attracted considerable attention from the academic and industrial communities. Numerous kinds of pigments, such as anthocyanin, carotenoid, chlorophyll, and flavonoid, extracted from various plant components, such as leaves, fruits, and flowers, have been tested as sensitizers. The photostability of the DSSC sensitizer material must be capable of undergoing many redox cycles without decomposition, and must also have the ability to carry attachment groups, such as phosphonate or carboxylate, to promptly graft it to the TiO2 oxide. This paper highlights and discusses the development of natural dye photosensitizers and the mechanisms affecting the dye stability.
The energy economy is highly dependent on oil, coal and natural gas, which constitute 37%, 27% and 20% of energy usage, respectively. However, the reserves of fossil fuels (e.g., crude oil) are ...limited and could run out in approximately 40 years based on a daily consumption of 82.5 million barrels and the current reserves to production (R/P) ratio. Solar energy is the source of nearly all energy on Earth. Of all renewable power sources, solar energy is the most easily exploitable, inexhaustible, quiet, and adaptable to different applications. Photovoltaic cells (PVCs) are devices that directly convert sunlight into electricity without pollution, sound, or moving parts, which makes them long-lasting and dependable. PVCs use an elegant method to take advantage of sunlight. Solar cells offer one of the most promising and environmentally friendly methods for producing electricity. This paper reviews the emergence, principles, electron kinetics and components of PVCs with a focus on the molecular engineering of several metal complexes, organic dyes and natural dyes that are used as photosensitisers in dye-sensitised solar cells (DSSCs).
The natural dyes anthocyanin and chlorophyll were extracted from Musa acuminata bracts and Alternanthera dentata leaves, respectively. The dyes were then applied as sensitizers in TiO2-based ...dye-sensitized solar cells (DSSCs). The ethanol extracts of the dyes had maximum absorbance. High dye yields were obtained under extraction temperatures of 70 to 80°C, and the optimal extraction temperature was approximately 80°C. Moreover, dye concentration sharply decreased under extraction temperatures that exceeded 80°C. High dye concentrations were obtained using acidic extraction solutions, particularly those with a pH value of 4. The DSSC fabricated with anthocyanin from M. acuminata bracts had a conversion efficiency of 0.31%, short-circuit current (Isc) of 0.9mA/cm2, open-circuit voltage (Voc) of 0.58V, and fill factor (FF) of 62.22%. The DSSC sensitized with chlorophyll from A. dentata leaves had a conversion efficiency of 0.13%, Isc of 0.4mA/cm−2,Voc of 0.54V, and FF of 67.5%. The DSSC sensitized with anthocyanin from M. acuminata bracts had a maximum incident photon-to-current conversion efficiency of 42%, which was higher than that of the DSSC sensitized with chlorophyll from A. dentata leaves (23%). Anthocyanin from M. acuminata bracts exhibited the best photosensitization effects.
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•I-V, IPCE, UV–Vis, XRD, FTIR, SEM and EDX have been studied.•The extraction yield is increased as the increasing of temperature.•The extraction yield is increased as the increasing of pH.•The higher performance of DSSC was achieved by anthocyanin dye.
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•Nine solvents used to extract natural dyes from C. fruticosa, P. amaryllifolius and H. polyrhizus.•Three natural dyes, namely, betanin, betaxanthins, and chlorophyll were extracted ...from a three plant species studied.•Investigating the best solvent to extract the natural dyes.•The adsorption of the dyes on TiO2 particles is better with solvents/water than with solvents alone.
Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.
Current study employs mixture of chlorophyll-anthocyanin dye extracted from leaves of Cordyline fruticosa as new sensitizers for dye-sensitized solar cell (DSSCs), as well as betalains dye obtained ...from fruit of Hylocereus polyrhizus. Among ten pigments solvents, the ethanol and methanol extracts revealed higher absorption spectra of pigments extracted from C. fruticosa and H. polyrhizus respectively. A major effect of temperature increase was studied to increase the extraction yield. The results indicated that extraction temperature between 70 and 80°C exhibited a high dye concentration of each plant than other temperatures. The optimal temperature was around 80°C and there was a sharp decrease of dye concentration at temperatures higher than this temperature. According to experimental results, the conversion efficiency of DSSC fabricated by mixture of chlorophyll and anthocyanin dyes from C. fruticosa leaves is 0.5% with short-circuit current (Isc) of 1.3mA/cm−2, open-circuit voltage (Voc) of 0.62V and fill factor (FF) of 60.16%. The higher photoelectric conversion efficiency of the DSSC prepared from the extract of H. polyrhizus was 0.16%, with Voc of 0.5V, Isc of 0.4mA/cm−2 and FF of 79.16%. The DSSC based betalain dye extracted from fruit of H. polyrhizus shows higher maximum IPCE of 44% than that of the DSSCs sensitized with mixed chlorophyll-anthocyanin dye from C. fruticosa (42%).
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•UV–Vis, FTIR, XRD, SEM, EDX, I–V curve and IPCE have been studied.•The extraction yield was increased as the increasing of temperature.•The higher η of DSSC of C. fruticosa was investigated by mixture of dye.
A lab-scale granular activated carbon sequencing batch biofilm reactor (GAC-SBBR), a combined adsorption and biological process, was developed to treat real wastewater from a recycled paper mill. In ...this study, one-consortia of mixed culture (4000–5000 mg/L) originating from recycled paper mill activated sludge from Kajang, Malaysia was acclimatized. The GAC-SBBR was fed with real wastewater taken from the same recycled paper mill, which had a high concentration of chemical oxygen demand (COD) and adsorbable organic halides (AOX). The operational duration of the GAC-SBBR was adjusted from 48 h to 24, 12 and finally 8 h to evaluate the effect of the hydraulic retention time (HRT) on the simultaneous removal of COD and AOX. The COD and AOX removals were in the range of 53–92% and 26–99%, respectively. From this study, it was observed that the longest HRT (48 h) yielded a high removal of COD and AOX, at 92% and 99%, respectively.
► We conducted an integrated process that combines adsorption and biological processes. ► We used real wastewater from a recycled paper mill in Kajang, Malaysia that contained high concentrations of COD and AOX. ► Increasing the hydraulic retention time of the reactor results in good removal efficiencies for COD and AOX.
Chlorophyll and ternatin were extracted from Zingiber officinale leaves and Clitoria ternatea flowers, respectively. These natural dyes were applied as sensitisers in TiO2-based dye-sensitised solar ...cells (DSSCs). Among 10 different solvents, the ethanol extracts revealed the highest absorption spectra of natural dyes extracted from Z. officinale and C. ternatea. A major effect of temperature increase was the increased extraction yield. High chlorophyll and ternatin yields were obtained under extraction temperatures of 80 °C and 70 °C, respectively. A notable decrease in C. ternatea dye concentration at temperatures >70 °C was also observed. High dye concentrations were obtained using acidic extraction solutions, particularly those with a pH value of 4. Experimental results showed that the DSSC fabricated with chlorophyll extracted from Z. officinale leaves exhibited a conversion efficiency of 0.30%, open-circuit voltage (Voc) of 0.56 V, short-circuit current (Isc) of 0.8 mA/cm−2 and fill factor (FF) of 57.93%. The DSSC sensitized with ternatin from C. ternatea flowers displayed a conversion efficiency of 0.13%, Voc of 0.54 V, Isc of 0.3 mA/cm−2 and FF of 81.82%.
•Application of response surface methodology for the optimization of extraction parameters.•Three independent extraction parameters such as solvent based on their boiling point, pH, and extraction ...temperature were optimized using D-optimal design in RSM.•Performance of the extract for DSSCs as a sensitizer with TiO2 semiconductor.
In the present work, the application of response surface methodology (RSM) for the optimization of process parameters in the chlorophyll extraction from Cordyline fruticosa leaves was performed. The absorbance of the extract obtained from the extraction process under different conditions was estimated using the D-optimal design in RSM. Three different process parameters such as the nature of organic solvent based on their boiling point (ethanol, methanol, and acetonitrile), pH (4–8) and extraction temperature (50–90°C) were optimized for chlorophyll extraction. The effects of these parameters on the absorbance or concentration of the extract were evaluated using ANOVA results of quadratic polynomial regression. The results showed a high R2 and adjusted R2 correlation coefficients of 0.9963 and 0.9921 respectively. Moreover, the analysis of the final quadric model based on the design experiments indicated an optimal extraction condition of pH of 7.99, extraction temperature of 78.33°C, and a solvent boiling point, 78°C. The predicted absorbance was 1.006, which is in good agreement with the experimentally obtained result of 1.04 at 665nm wavelength. The application of pigment obtained under the optimal condition was further evaluated as a sensitizer for the dye sensitized solar cells. Maximum solar conversion efficiency (η) of 0.5% was achieved for the C. fruticosa leaf extract obtained under the optimum extraction conditions. Furthermore, the exposure of the leaf pigment to 100mW/cm2 simulated sunlight yielded a short circuit photocurrent density (Isc) of 1.3mA, open circuit voltage (Voc) of 616mV, and a fill factor (ff) of 60.16%.
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