Top PDF Natural Dyes as Photosensitizers for Dye-sensitized Solar Cells

Natural Dyes as Photosensitizers for Dye-sensitized Solar Cells

Natural Dyes as Photosensitizers for Dye-sensitized Solar Cells

dye-sensitized solar cells (DSSCs) were assembled us- ing extracts from eight natural dyes as sensitizers for nanocrystalline ZnO photoelectrodes. The ZnO nano- particles, with crystallite mean value of 12 nm as indi- cated from XRD data, were synthesized at pH 12. SEM pictures and TEM micrographs of the ZnO powder re- vealed homogeneous and well defined nanoparticles with size of about 15 nm, and shows that the powder has a porous agglomerate structure consisting mainly of spherical crystalline particles with about 15-20 nm diameter, respectively.
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Dyes Extracted from Safflower, Medicago Sativa, and Ros Marinus Oficinalis as Photosensitizers for Dye-sensitized Solar Cells

Dyes Extracted from Safflower, Medicago Sativa, and Ros Marinus Oficinalis as Photosensitizers for Dye-sensitized Solar Cells

In this subsection, the J-V characteristic results of the two DSSC sets fabricated using untreated FTO and dyed with the three extracts obtained before and after grinding the leaves are presented. The J-V characteristic curves for the set sensitized with extracts of safflower, Medicago sativa, and Ros marinus before grinding the leaves are shown in Fig. 2 whereas those of the cells sen- sitized with the three extracts after grinding the leaves are illustrated in Fig. 3. It is noticed that the DSSCs sensitized with the extracts of grinded leaves gave better results than those sensitized with the extracts of un- grinded leaves. This can attributed to the better solubili- ty of all the compounds of the raw material when grind- ing the leaves. In Table 1, the Photoelectrochemical pa- rameters including short circuit current J sc , open circuit
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Recombination Study of Dye Sensitized Solar Cells with Natural Extracts

Recombination Study of Dye Sensitized Solar Cells with Natural Extracts

Natural dyes can be used in dye sensitized solar cells (DSSCs) to generate low-cost devices, although with low light harvesting because of energy losses from the recombination process. This study investigates recombination reactions in DSSCs with natural dyes extracted from eggplants, plums, and hibiscus flowers. Titanium dioxide films were coated on a fluorine-doped tin oxide glass conductor substrate by the doctor blading method and impregnated in a dye solution for 24 h. Electrodeposited platinum was used as the cathode, and I 3
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A Photoelectrochemical Study of Bioinspired 2-Styryl-1-Benzopyrylium Cations on TiO2 Nanoparticle Layer for Application in Dye-Sensitized Solar Cells

A Photoelectrochemical Study of Bioinspired 2-Styryl-1-Benzopyrylium Cations on TiO2 Nanoparticle Layer for Application in Dye-Sensitized Solar Cells

solar cells (DSSCs). Integration of these 2-styryl-1-benzopyrylium salts with the semiconductor allow for the performance of highly specific functions suitable for smart applications in material science. Spectroscopic and photoelectrochemical measurements conducted on these five bio-inspired dyes, in solution and upon adsorption onto titanium dioxide films, allowed detailed discussion of the anchoring ability of the different donor groups decorating the 2-styryl-1-benzopyrylium core and have demonstrated their ability as photosensitizers. Our results suggest that the introduction of a dimethylamino group in position 4 0 of the 2-styryl-1-benzopyrylium skeleton can alter the conjugation of the molecule leading to larger absorption in the visible region and a stronger electron injection of the dye into the conduction band of TiO 2 . Moreover, our experimental data have been
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Application of polyoxometalate-ionic liquids (POM-ILs) in dye-sensitized solar cells (DSSCs)

Application of polyoxometalate-ionic liquids (POM-ILs) in dye-sensitized solar cells (DSSCs)

modified photoanodes containing POMs have shown an improve- ment of the photovoltaic performance, which was interpreted as being related to reduced electron recombination, increased elec- tron lifetime and in some cases also to enhanced light harvesting. They have also been reported as photosensitizers [14,15] or co- sensitizers [15–17] in n-type DSSCs and in p-type DSSCs as pure inorganic dyes [18,19] or co-sensitizers [19,20]. When they are used as photosensitizers the efficiencies of the solar cells are in the range of 0.029–0.2% [14,15] in n-type DSSCs, and values of 0.0016 to 0.038% for p-type cells [18,19]. While used as co- sensitizers, the overall power conversion efficiency is enhanced through increasing spectral absorption, accelerating electron transport and restraining charge recombination [15,17] or through
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Application of transitionmetaloxidebased  thin films on third generation solar cells

Application of transitionmetaloxidebased thin films on third generation solar cells

One of the greatest challenges of our time is to devise means to provide energy in a sustainable way to attend an exponentially growing demand. The energy demand is expected to grow 56% by 2040. In this context, the use of clean and sustainable sources of energy is imperative. Among these sources, solar energy is the only one which can meet the total world energy requirement even considering such large growth in demand. The solar power incident on the Earth’s surface every second is equivalent to 4 trillion 100-watt light bulbs. Photovoltaic solar cells are one of several ways to harness solar energy. These cells convert solar energy directly into electricity. Commercial photovoltaic devices are already a reality, but their share of the world energy matrix is still quite small, mainly due to the high costs. Next generation photovoltaics open a number of new possibilities for photovoltaic energy applications that can potentially decrease the overall cost of energy production. Transition metal semiconductor oxides are promising materials that can be produced by low cost methods and offer interesting new features. The use of these materials in next generation photovoltaics is therefore a very promising and interesting application. In this thesis work zinc, titanium and vanadium oxides were used in next generation solar cells. Thin films of zinc oxide were synthesized by the low cost and environmentally friendly techniques of electrodeposition and hydrothermal synthesis and applied as working electrodes in highly efficient dye sensitized solar cells (DSSCs). The films were characterized by structural and optical techniques while the cells were tested by current vs. voltage and quantum efficiency measurements. The efficiencies of these cells were as high as 2.27% using ZnO thin films without any post deposition treatment. Moreover, natural dyes extracted from plants of northeastern Brazil were applied as sensitizers in DSSCs assembled with commercial available TiO 2 as working
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Complexo Zinco-produto natural: desenvolvimento e aplicação como fotossensibilizador para célula solar / Zinc-natural product complex: development and application as a photosensitizer for solar cells

Complexo Zinco-produto natural: desenvolvimento e aplicação como fotossensibilizador para célula solar / Zinc-natural product complex: development and application as a photosensitizer for solar cells

The generation of energy by renewable sources, such as solar technology, for example, has increased in recent years as a way to guarantee current consumption without compromising the natural resources and the needs of future generations. Performance under low light intensity makes the dye-sensitized solar cell (CSSC) promising for internal applications in autonomous electronic devices. But for this technology to be competitive, it is essential to improve efficiency and stability and reduce manufacturing costs, with a sustainable life cycle. In this sense, the objective of this research was the development and application as a sensitizer in a solar cell of the [(μ-antrarufinate)Zn 2 (1,10´-
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Toward sustainability: solar cells sensitized by natural extracts.

Toward sustainability: solar cells sensitized by natural extracts.

TOWARD SUSTAINABILITY: SOLAR CELLS SENSITIZED BY NATURAL EXTRACTS. The present work reports the use of anthocyanins extracted from mulberry (Morus Alba L.), raspberry (Rubus Idaeus L.) and blueberry (Vaccinium myrtillus L.) as sensitizers in dye-sensitized solar cells. The conversion eficiency of these devices is dependent on the extracts employed and can be rationalized in terms of their composition and spectral properties. Solar cells sensitized by the mulberry extract showed the highest eficiency among the fruits investigated. Moreover, a 16 cm 2 active area solar cell with the mulberry extract has presented fair good
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Dye-sensitized solar cells using fluorone-based ionic liquids with improved cell efficiency

Dye-sensitized solar cells using fluorone-based ionic liquids with improved cell efficiency

activity of these metal free dyes in terms of current –potential curve, open-circuit potential, fill factor, and overall solar energy conversion e fficiency which have been evaluated under 100 mW cm 2 light intensity. We developed a strategy to improve the light harvesting of these conventional dyes by simple cationic exchange which was accompanied by a minimum of 30% increase in the cell photovoltaic conversion e fficiency. Also, for Eosin B the binding to TiO 2 apparently allows reduction of the –NO 2

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RESULTS AND DISCUSSION Structural parameters

RESULTS AND DISCUSSION Structural parameters

Abstract: Dye-sensitized solar cells (DSSCs) based on triphenylamine (TPA) as a donor group linked with the acceptor cyanoacrylic acid electron acceptor by 2,2’-bithiophene as π-bridged (D-π-A) has been investigated by Density Functional Theory (DFT) at the B3LYP/6-311G(d,p) level of theory, to establish the conformational orientation of cyanoacrylic acid group as well as evaluate the effect of planarizing the 2,2’-bithiophene unit in position 3 and 3’ by electron withdrawing or donor groups on the electronic structure properties of ground and doping(n,p) states. Also, the Time Dependent Density Functional Theory (TD-DFT) at the CPCM-TD-CAM-B3LYP//CAM-B3LYP/6-311G(d,p) level of theory were selected to modulate the electronic absorption spectra and charge-transfer capabilities of the molecules analyzed in the present work. The results indicate that adding an auxiliary donor or withdrawing group to the 2,2’-bithiophene in the (D-π-A) arrangement allow to modify the LUMO’s energy of the dyes, while the HOMO´s energy is slightly affected.
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SOLAR CELLS SENSITIZED WITH NATURAL DYES: AN INTRODUCTORY EXPERIMENT ABOUT SOLAR ENERGY FOR UNDERGRADUATE STUDENTS.

SOLAR CELLS SENSITIZED WITH NATURAL DYES: AN INTRODUCTORY EXPERIMENT ABOUT SOLAR ENERGY FOR UNDERGRADUATE STUDENTS.

containing an iodide/triiodide redox couple was used in lieu of the use of liquid solutions to prevent any leakage in the devices. A maximum solar-to-electric energy conversion of 0.26 ± 0.02% was obtained for the solar cell prepared with annatto extracts. This experiment was an effective way to illustrate to the undergraduate students how to apply some of the chemical concepts that they learned during their chemistry course to produce electric energy from a clean and renewable energy source. Teachers could also exploit the basics of the electronic transitions in inorganic and organic compounds (e.g., metal-to-ligand charge transfer and π-π* transitions), thermodynamics (e.g., Gibbs free energy), acid–base reactions in the oxide solid surface and electrolyte, and band theory (i.e., the importance of the Fermi level energy).
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Quím. Nova  vol.35 número3

Quím. Nova vol.35 número3

Dyes can be classified according to their chemical structure in terms of chromophore groups, which are responsible for the different dye colours produced. Azo dyes represent the most important dye class used in the textile industry. They are characterized by the pres- ence of one or more azo chromophores (N=N) and bonds between two or more aromatic rings. Anthraquinone dyes constitute the second most important class of textile dyes, which have the chromophore groups, =C=O and =C=C=, forming an anthraquinone complex. 5,6

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Recent Advancements and Techniques in Manufacture of Solar Cells: Organic Solar Cells

Recent Advancements and Techniques in Manufacture of Solar Cells: Organic Solar Cells

Organic photovoltaics are made of electron donor and electron acceptor materials rather than semiconductor p-n junctions. The molecules forming the electron donor region of organic p-v cells, where exciton electron-hole pairs are generated, are generally conjugated polymers processing delocalized π electrons that result from carbon p orbital hybridization. These π electrons can be excited by light in or near the visible part of the spectrum from molecules highest occupied molecular orbital(HOMO) to the lowest unoccupied molecular orbital(LUMO), denoted by π- π* transition. The energy band gap between these orbitals determines which wavelength of light can be absorbed. Unlike in an inorganic crystalline PV cell material, with its band structure and delocalized electrons, excitons in organic photovoltaics are strongly bound with an energy between 0.1 and 1.4ev .This strong binding occurs because electronic wave functions in organic molecules are more localized, and electrostatic attraction can thus keep an electron and a hole together as an exiction. The electron and hole can be separated by providing an interface across which the chemical potential of electron decreases. The material that absorbs the photon is the donor, and the material which acquires the electron is the acceptor. In Fig.3, the polymer chain is the donor and the fullerene is the acceptor. After dissociation, the electron and hole may be still joined as a “geminate pair”, and an electric field is then required to separate them.
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Androgen-Sensitized Apoptosis of HPr-1AR Human Prostate Epithelial Cells.

Androgen-Sensitized Apoptosis of HPr-1AR Human Prostate Epithelial Cells.

Total RNA was extracted from the cells using Qiagen RNeasy Mini Kit (74106, Qiagen) with on-column DNase treatment (79254, Qiagen). Random-primed cDNA was prepared from 2 μg of total RNA using the ProtoScript First Strand cDNA kit (E6300L, New England Biolabs, Ips- wich, MA) and diluted 5-fold in water. One μl of diluted cDNA was used as template for QPCR using StepOnePlus Real-Time PCR System (Applied Biosystems, Grand Island, NY). Primers were designed using Primer3 (http://frodo.wi.mit.edu) and those that efficiently amplified [51] single products of the expected size were used for QPCR. Primers for QPCR amplicons are in Supporting Information (S1 Table). The QPCR was achieved using the follow- ing method: a denaturation and polymerase activation step at 94°C for 1 min and then 40 cycle consisting of 94°C for 10 s, 57°C for 10 s, and 72°C for 20 s. Data were analyzed using the com- parative threshold cycle (Ct) method [52] and multiple control genes, including ADAM15, PYGO2, TBP and GAPDH, which are not regulated by androgen or AR. Following normaliza- tion to control gene cDNA levels, which is reflected in the ΔCt values, the relative quantifica- tion (RQ) of the fold change for each treatment compared to reference control was determined using the following equation: RQ = 2 (nd mu / 2 (/ 2m reference) . The mean of the log 2 RQ and stan-
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Bioremediation of dyes by fungi isolated from contaminated dye effluent sites for bio-usability

Bioremediation of dyes by fungi isolated from contaminated dye effluent sites for bio-usability

The two selected fungal strains were further tested for their ability to decolorize on PDA and Sabouraud Dextrose Agar (SDA) medium, Himedia, Mumbai, India. This was done to select which medium support better growth and dye decolorization activities of selected fungal isolates. Ini- tially, all the three fungal strains were grown as previously described. Following incubation, fungal mycelial agar plugs (~5 mm 2 ) were cut approximately 5 mm from the col- ony margin and inoculated on test tubes (in triplicates) each pre-filled with 2 mL of the Potato Dextrose Agar (PDA) and SDA medium, supplemented separately with either with following dye 0.01% (w/v) Malachite green, Nigrosin and Basic fuchsin, respectively (Lopez et al., 2006). The culture tubes were then incubated at room temperature (~ 25 °C). The growth of the fungi and its ability to decolorize the dye were observed weekly up to four weeks. The depth of dye decolorization (in mm) indicated by clear- ing of the dye was then measured. Based upon growth of fungal strains and dye decolorization, for further studies PDA medium was chosen.
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Hedgehog inhibition promotes a switch from Type II to Type I cell death receptor signaling in cancer cells.

Hedgehog inhibition promotes a switch from Type II to Type I cell death receptor signaling in cancer cells.

cIAP-2, and XIAP mRNA expression was determined after cyclopamine treatment or shRNA to SMO. Both XIAP and cIAP-1 mRNA levels were decreased by SMO inhibition (Fig. 1C). The clinical relevance of IAP regulation was assessed in tumor and adjacent benign samples from patients with cholangiocarcinoma. A two-fold increase in XIAP mRNA levels was observed in tumor tissue (Fig. 1D). The levels of cIAP-1 and -2 were not significantly different. That cIAP-1 is not elevated in tumor samples despite regulation by Hedgehog (Fig. 1C) may indicate additional as-yet- unknown factors also contribute to control of IAP expression in the Figure 3. Cyclopamine sensitizes cells to TRAIL-induced cell death despite knockdown of Bid or Bim. A, Immunoblot analysis was performed on whole cell lysates obtained from KMCH cells stably transfected with the specific shRNA targeting Bid or Bim, using indicated antisera. Actin was used as a loading control. B, KMCH cells stably transfected with Bid- or Bim-shRNA and untransfected parental KMCH cells were treated with Fas agonistic antibody CH-11 (100 mg/mL) for 5 hours followed by DAPI staining. Cells with apoptotic morphology were counted. Mean 6 SEM, ***p,0.001 compared to parental cells treated with CH-11. C, In parallel, caspase-3/7 activity was measured in cells treated as in panel B. Mean 6 SEM, ***p,0.001. D, KMCH cells stably transfected with Bid- or Bim-shRNA were pretreated with vehicle or cyclopamine (5 mM) for 24 hours, and then treated with TRAIL (5 ng/mL) for 5 hours followed by DAPI staining. Cells with apoptotic morphology were counted. Mean 6 SEM, ***p,0.001 compared to cells treated with TRAIL alone. E, KMCH stable cell lines were treated as in panel D, and after 5 hours caspase-3/7 activity was measured. Mean 6 SEM, ***p,0.001 compared to cells treated with TRAIL alone. F, Whole cell lysates from KMCH, HuCCT-1, and Mz-ChA-1 cells treated with vehicle or cyclopamine (5 mM) for 24 hours were analyzed by immunoblot using anti-Bcl-2, Mcl-1, or Bcl-x antisera. Actin was used as a loading control. G, Whole cell lysates were obtained from shBid-, shBim- and untransfected parental KMCH cells treated with vehicle or cyclopamine (5 mM) for 24 hours and were analyzed by immunoblot using anti-Bcl-2, Mcl-1, or Bcl-x antisera. Actin was used as a loading control.
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Multi-Enzymatic Systems for Cleaning-up Synthetic Dyes from the Environment

Multi-Enzymatic Systems for Cleaning-up Synthetic Dyes from the Environment

Quinones, characteristic of two carbonyl groups in an unsaturated six- member carbon ring, constitute an important class of ubiquitous and naturally occurring compounds present in the environment as well as in prokaryotic and eukaryotic cells (Deller et al. 2008, Liu et al. 2008a, Sollner & Macheroux 2009). Quinones are metabolites that can participate in deleterious redox cycling, which can lead to the accumulation of reactive oxygen species such as superoxide, hydrogen peroxide and hydroxyl radical, and can impair lipids, proteins and nucleotides (Liu et al. 2009). Azoreductases with quinone reductase activity may have a protective effect against quinone-based oxidative cell damage and may be involved in the detoxification of quinones (Liu et al. 2009, Liu et al. 2008a; Sollner & Macheroux 2009). Therefore, these enzymes are assumed to take part in the organism’s enzymatic detoxification systems; e.g., the azoreductases from E. coli and B. subtilis were implicated in the cellular response to thiol-specific stress (Leelakriangsak et al. 2008, Liu et al. 2009, Towe et al. 2007) and Lot6p, the azoreductase homologue in S. cerevisiae has been implicated in the response to oxidative stress (Sollner et al. 2009, Sollner et al. 2007). The flavin-containing enzymes were also shown to use other substrates such as nitroaromatic substrates (Liu et al. 2007). Further study of the genes coding for these xenobiotic-metabolizing enzymes may help to reveal factors that govern the horizontal transfer of genetic information among bacterial species in the environment. Overall, as additional members of this family of enzymes are discovered, the list of transformed substrates will continue to grow.
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REMOVAL OF REACTIVE DYES FROM WASTEWATER OF TEXTILE INDUSTRIES BY USING ENVIRONMENTAL FRIENDLY ADSORBENTS

REMOVAL OF REACTIVE DYES FROM WASTEWATER OF TEXTILE INDUSTRIES BY USING ENVIRONMENTAL FRIENDLY ADSORBENTS

Abstract: This paper is aimed at developing a method to treat wastewater by using inexpensive adsorbents. Textile industries produce wastewater, otherwise known as effluent, as a bi-product of their production. The effluent contains several pollutants. Among the various stages of textile production, the operations in the dyeing plant, which include pre-treatments, dyeing, printing and finishing, produce the most pollution. The textile dyeing wastes contain unused or partially used organic compounds, and high level of different pollutants. They are often of strong color and may also be of high temperature. When disposed into water bodies or onto land these effluents will result in the deterioration of ecology and damage to aquatic life. Furthermore they may cause damage to fisheries and economic loss to fishermen and farmer, there may be impacts on human health which can be removed with the help of an effluent treatment plant (ETP). The “clean” water can then be safely discharged into the environment and ultimately save our environment from pollution. In this study, rice husk and cotton dust were used as an adsorbent. In this research work waste water was characterized with this useless adsorbents. The parameters which were tested in this study are DO, BOD, COD, TS, TDS and TSS. The results showed that the selected bio adsorbents have good potential for removal of reactive dyes from textile effluent.
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Adsorption of congo red dye from aqueous solution onto amino-functionalized silica gel

Adsorption of congo red dye from aqueous solution onto amino-functionalized silica gel

Most industrial wastewater treatment plants utilize activated carbon as adsorbent to remove dyes and other organic pollutants, in reason of its considerable adsorption capacity for these contaminants. However, its widespread use is still limited, mainly due to the often prohibitive cost, besides the difficulty in regeneration and final disposal (TOR & CENGELOGLU, 2006; SHARMA et al., 2011; WANG et al., 2011; XIA et al., 2011; ZHU et al., 2011). For this reason, the number of studies on the viability of low-cost alternative adsorbents for dye removal, such as waste and biomass-based materials, has increased over recent years (AKSU, 2005; GUPTA & SUHAS, 2009; MITTAL et al., 2009; AHMAD & KUMAR, 2010; SALLEH et al., 2011; SHARMA et al., 2011; ZHU et al., 2011). Unfortunately, the adsorption capacities of these materials are generally non-attractive (XIA et al., 2011). Thus, high-capacity and low-cost adsorbents are still under development toward reducing the adsorbent amount and minimizing disposal problems in dye wastewater treatment systems (YIGˇITOGˇLU & TEMOÇIN, 2010; XIA et al., 2011). In this context, silica gel functionalized superficially with differ- ent active moieties is of particular interest. Silica gel is an amorphous inorganic support well known by its high surface area, high thermal and chemical stability, mechanical and swelling resistance, possibility of repeated use and inexpensive cost (ATIA; DONIA; AL-AMRANI, 2009; DONIA et al., 2009; MAHMOODI; KHORRAMFAR; NAJAFI, 2011). This material is able to interact with various organic substances when it is grafted with organosilyl compounds, making it a promising adsorbent for selective adsorption. Recently, silica gel modified with aminoorganosilanes has successfully been applied for the removal of dyes (ANDRZEJEWSKA; KRYSZTAFKIEWICZ; JESIONOWSKI, 2007; CESTARI et al., 2009; DONIA et al., 2009), including azo dyes, the most widely used class of industrial dyes, constituting 60% to 70% of all produced dyestuffs (YIGˇITOGˇLU & TEMOÇIN, 2010).
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