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Poly(3-alkylthiophenes), P3AT, are organic polymers formed by conjugate structures with conductive properties. Zinc oxide (ZnO) has been used as an electron acceptor in hybrid solar cells because it offers electron transport properties and can be synthesized by methods in which the variation of synthesis parameters allows morphological control. Different ZnO morphologies allow for distinct properties in terms of electronic transport at the interface of solar cells. ZnO particles were synthesized by the co-precipitation method. ZnO films were deposited by spin-coating in Fluorine Tin Oxide (FTO) and then immersed in solutions containing poly (3-hexylthiophene) (P3HT) or poly (3-octylthiophene) (P3OT) polymers. The cell was assembled in the form of a sandwich consisting of: FTO/ZnO,P3AT/Iˉ,I3ˉ/Pt/FTO. UV-vis measurements were performed for bandgap calculation, scanning electron microscopy (SEM), X-ray diffraction (XRD), and J-V curves. The ZnO/P3HT cell presented the best values of J, V and η, indicating an improvement in the electronic transfer processes, with a value of η = 0.56%. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSC) are devices to solar energy conversion, which present low production costs and high photoelectrochemical stability. The aim of this study was to investigate the synthesis of TiO2 by Pechini methodology, using C12H28O4Ti and TiCl3 as precursors, and their application in solar cell sensitized by N719 dye. The characterization techniques employed were Scanning Electron Microscopy (SEM), UV-VIS Spectroscopy, X-ray diffraction (XRD), photochronoamperometry, j-V Curves and EIS plots. The results demonstrated a high crystallinity and surface area to particles obtained with C12H28O4Ti as precursor. The highest photoconversion energy efficiency reached was to TiO2 using C12H28O4Ti with PCE= 4.17±0.13% with photoelectrochemical parameters of jsc= 5.53 ±0.08, Voc= 0.78±0.07 FF=0.58±0.05 and less resistive to charge transport with te= 53 ms. [ABSTRACT FROM AUTHOR]

The solar cells of semiconductors oxides have been largely studied. The zinc oxide (ZnO) and niobium oxide (Nb2O5) used in this work presented important physical-chemical characteristics in use of photovoltaic devices. The Nb2O5 presents the capacity of minimizing effects of charge recombination in the process of energetic conversion of solar cells. The oxides used in this work were characterized by the technique X-ray diffraction. The solar cells containing 5% of Nb2O5 presented of best results in a relationship of the electron transfer process, reaching the efficiency of 0.42%. [ABSTRACT FROM AUTHOR]

In this study, it was investigated the photovoltaic parameters of Dye Sensitized Solar Cells (DSSC) and the thin coating morphology of TiO2 by Doctor Blading and Spin Coating methods, sintered at 450 °C and 450 °C with a heating rate of 0.4 °C s-1, using a natural dye extract from Hibiscus. These properties were studied by scanning electron microscopy (SEM), photochronoamperometry and curves j-V. It was demonstrated that all solar cells produced are photosensitive with an excellent charge injection. The cell with a better energy conversion (jsc = 0.53 mA cm-2; Voc= 0.471 V and FF= 0.518), uniform and flawless morphology was obtained to cell coated by Doctor Blading method, with a heat treatment of 450 °C/0.4 °C s-1. [ABSTRACT FROM AUTHOR]

The intensive use of fossil fuels has had consequences coming from the instability of the reserves, due to the finitude of the resource, as well as the environmental impacts that the use of these fuels entails, such as the increasement of greenhouse gases. In this way, a promising alternative found to attenuate such problems is the production of biofuels, such as biodiesel, in which are used raw materials from renewable sources. They contribute to decrease dependence on oil and reduce the greenhouse effect. However, after biodiesel is produced, it is subject to degradation reaction when in contact with air, light, and temperature, which promotes the reduction of its quality. To slow down the degradation reaction, antioxidants are added to the biodiesel, providing greater oxidation stability. Antioxidants are substances that retard oxidation and can be natural, such as ascorbic acids or synthetic substances. Thus, this work aimed to evaluate the efficiency of ascorbic acid as an antioxidant in soybean biodiesel. Oxidative stability tests were performed and it was observed that the best concentration of ascorbic acid in soybean biodiesel, as antioxidant, is 27.5 g L-1. [ABSTRACT FROM AUTHOR]

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