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Abstract : Optical Response and Photovoltaic Performance of Organic Solar Cells Based on DH6T:Alq3 Active Layer
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Abstract: This research work reports on the optical and photovoltaic performance of dihexyl-sexithiophene (DH6T) doped with various molar percentages of tris-8-hydroxyquinolinate aluminium (Alq3) dissolved in chloroform/hexane co-solvent. Films of DH6T(1-x)Alq3(x) composite have been produced by casting technique aiming at investigating their absorption edge energies (Eabs) and hence identifying the optimum content of Alq3. It was found that by introducing a controlled amount of Alq3, the value of Eabs can be tuned from 2.69 eV to 1.76 eV. An empirical equation was derived to fit the obtained experimental data, by which an optimum Eabs at molar concentration of (x ≈ 25%) was predicted. Finally, organic solar cells based on the optimum active layer content were fabricated and tested. Comparably, it was observed that the photovoltaic performance of the DH6T:Alq3 based devices is much better than that achieved for the DH6T:PCBM based ones. Efficiency and fill factor for the devices based on DH6T(0.75)Alq3(0.25) active layer were found to be 0.22% and 26.5%, respectively, while those for DH6T:PCBM based devices were about 0.01% and 24%, respectively. Keywords: Alq3, DH6T, Organic composite, Doping, Absorption edge, organic solar cells.Download Full Article |
Abstract : Investigation of Photo-Absorption and Current-Voltage Properties of Liquid Extracts from Fruits for Organic Solar Cells Application
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Abstract: In this research work, the optical absorption and photo-current characteristics of black grape, strawberry and orange solutions were investigated. The solutions were extracted from fresh fruits and UV-V is spectrophotometer was utilized to record the absorption spectra of the samples. Besides, the photo-current properties were investigated via current-voltage characteristics of the fruit solutions under illumination. The results showed that energy gaps of the fruits are located within the visible spectrum. Energy gap of 1.84eV was found for the black grape, 2.11eV for strawberry and 3.10eV for the orange solution. The broad absorption spectra for black grape and strawberry have proved the fruits capability to harvest solar energy. Additionally, the enhanced photo-current activity of the fruit solutions under light suggested their potential application for the organic and/or dyes solar cells. Keywords: Absorption, energy gap, black grape, strawberry, orange, dyes solar cells.Download Full Article |
Abstract : Effect of Nano Surface Topography on Electrical Properties of Lead Sulfide (PbS) Films Deposited on Polymer Substrate
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Abstract: Lead sulfide (PbS) films were deposited on polymide (PI) plastic substrate chemical spray pyrolysis technique at substrate temperature in the range 250-350 oC. Effects of substrate temperature on the electrical properties of the films were studied. In addition, the effect of nano surface topography on electrical properties of PbSfilms was studied. The deposited films were analyzed with atomic force microscope and Hall measurements to determine their electrical characteristics. AFM data shows that the root mean square (RMS) surface roughness of the PbS film increases with increasing substrate temperature. At room temperature, electrical resistivity of the PbS films varies from 9.54x103 to 1.14x103 Ω.cm, respectively. Keywords: PbS, Polyimide, Chemical Spray Pyrolysis, Substrate Temperature, Electrical properties.Download Full Article |
Abstract : In Vitro Polarized Resonance Raman Study of N719 and N719-TBP in Dye Sensitized Solar Cells
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Abstract: The working efficiency of dye-sensitized solar cells (DSCs) depends on the long-term stability of the dye itself and on the microscopic structure of the dye-semiconductor interface. Previous experimental studies of DSCs based on ruthenium dye with bipyridine ligands (N719) adsorbed to the TiO2substrate applied FTIR,un-polarized Raman (RS) and un-polarized resonance Raman (RRS) spectroscopy. In the un-polarized RRS studies of N719/TiO2 – DSCs the discussion of the adsorption of N719 was based on the rather weak carbonyl or carboxyl group stretching vibrations and on minor spectral changes of overlapping Raman modes, whereas conclusions about the dye-stability was based on the observation that fresh and aged DSCs had almost identical RRS spectra. In the present paper we address the problems mentioned above, by utilizing the unique property of Raman scattering that the polarization of the scattered light is generally different from the polarization of the laser light. When the excitation is chosen within the visible absorption band of N719 only the skeleton ring-modes in N719 are enhanced and are observed as the most intense bands in the RRS spectra. We demonstrate by experimental results on N719/TiO2 – DSCs that by combining an analysis of the wave number dependent polarization of these modes with the small shifts observed in the visible absorption spectra of adsorbed, non-adsorbed molecules and degradation products new and more reliable information about dye stability and about the adsorption of the dye on TiO2 can be obtained. Furthermore it is found that the polarization fluorescence anisotropy is very different for adsorbed and non-adsorbed dye molecules. This information is automatically obtained when processing the Raman data. The conclusion is that if the polarization properties of the resonance Raman spectra are analyzed instead of just analyzing the minute spectral changes of the (weaker) Raman bands the potential of RRS as an on-site tool for investigation of DSCs can be greatly improved. Keywords: Dye sensitized solar cell, Polarized Raman, polarized Fluorescence.Download Full Article |
