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Different natural dye extracts have been prepared and used as sensitizers in the fabrication of dye-sensitized solar cells (DSSCs). These dyes have been extracted from both fresh and dried raw materials. The absorption spectra of these dyes have been investigated by UV-VIS spectrophotometry. DSSCs were assembled using TiO2 and ZnO nanostructured, mesoporous films. Photovoltaic parameters such as short circuit current density Jsc, open circuit voltage Voc, fill factor FF, and overall conversion efficiency η for the fabricated cells were determined under 100 mW/cm2 illumination. The immersion time of the nanocrystalline-TiO2 electrode in spinach extract and the temperature at which this process occurs were optimized. The optimal dying temperature is found to be 60 °C and the efficiency of the DSSC is found to saturate to 0.29% after 12 hr of soaking in the dye solution.

This work emp loys extracts fro m Walnuts, Rhubarb, and Po megranate as natural dyes for fabricat ion of dye-sensitized solar cells (DSSCs). ZnO nanoparticles with crystallite mean value 12 n m as confirmed fro m XRD data have been synthesized at pH 12. SEM p icture of the ZnO powder reveals ho mogeneous and well defined nanoparticles with size of about 15 n m. TEM micrograph shows that the powder has a porous agglomerate structure consisting main ly of spherical crystalline particles with about 15-20 n m diameter. ZnO films were deposited on Fluorinated Tin Oxide (FTO) coated glass sheets followed by sintering at 450℃. The samples were sensitized by soaking in the dye solution. A Graphite slab was used as a back electrode, and redo x was employed as an electrolyte. Each cell was illu minated with light intensities in the range 40,000-100,000 Lux to measure the photovoltaic parameters. The experimental results shows that the highest I sc value is obtained fro m the DSSC sensitized with Rhubarb extract while the highest V oc value is obtained from the DSSC sensitized with the Walnuts extract. The P max of the DSSC sensitized by the Walnuts extract is greater than those sensitized by Rhubarb and Po megranate ext racts. Moreover, the open circuit voltage V oc decay was found to closely fo llo w a pseudo single exponential form.

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Recently, one-dimensional periodic ternary photonic crystals have shown outstanding properties when compared to onedimensional periodic binary photonic crystals. In this work, a ternary photonic crystal is proposed as a temperature sensor. The structure of the ternary photonic structure is considered Si/polymer/SiO 2. The transmission spectra of the proposed ternary photonic structure are studied for different temperatures. It is observed that as the temperature increases, the transmission peak shifts toward higher wavelengths due to thermo-optic and thermal expansion coefficients of the polymer. It is found that the temperature-sensitive transmission peak shift is considerably enhanced due to the insertion of the polymer layer between Si and SiO 2 to constitute a ternary photonic crystal.

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