The electronic structure and excitation properties of the Dipyridyl dye molecule and its derivatives were performed using the Gaussian 09 software package.Calculations were performed based on the framework of density functional theory (DFT) with the Becke 3-parameter-Lee-Yang-Parr (B3LYP) functional, where the 6-311+ G (d,p) basis set was employed.The HOMO-LUMO energy gap, the improved light harvesting efficiency(LHE) and free energy change of electron injection of newly designed sensitizers revealed that this material would be an excellent sensitizer.Each of the molecules was theoretically analyzed and these could help in designing more efficient functional dye-sensitizers.
Dye-sensitized solar cells are an attractive third generation photovoltaic emerging technology. These solar cells are currently alternative to the conventional inorganic silicon-based cells because of the advantages, such as low-cost materials and simple fabrication processes. Some challenges remain in the field of research, such as long-term stability and operation lifetime. Third-generation solar technologies include solar cells sensitized by dye materials (DSSCs), quantum dots (QDs) and perovskites. Among of them, DSSCs are the longest-standing third-generation solar technology. Currently, DSSCs using inorganic metal complex dye(e.g.RU), synthetic/natural organic dyes in different type of electrolyte. Recently, the two systems have achieved similar record efficiencies approaching 12% and other exceeding 13%. In this review, we will highlight the recent research on sensitizers for DSSCs, including ruthenium complexes, metal-free organic dyes, and natural dyes with their corresponding efficiencies. Also, the latest approaches to enhance the performance of natural dyes have been discussed.
In this work, the thin films of vanadium oxide on Si substrate were deposited by RF sputtering and pulsed laser deposition method. The as-deposited samples were annealed in argon atmosphere at 500°C for 1 h and cooled at natural rate in argon atmosphere. The as-deposited and annealed samples were irradiated with 100 MeV Ag ions at different fluences. Structural characterizations were done by grazing incidence X-ray diffraction (GIXRD) and Raman spectroscopy at room temperature. GIXRD and Raman spectra revealed that phase transformation took place after swift heavy ions irradiation and the ratio of oxygen/vanadium concentration of the films decreased. The phase transformation and change in concentration may be due to transiently molten cylindrical zone created by the passage of swift heavy ions in the material.
Energetic ion beams are proving to be versatile tools for modification and depth profiling of materials. The energy and ion species are the deciding factor in the ion-beam-induced materials modification. Among the various parameters such as electronic energy loss, fluence and heat of mixing, velocity of the ions used for irradiation plays an important role in mixing at the interface. The present study is carried out to find the effect of the velocity of swift heavy ions on interface mixing of a Ti/Bi bilayer system. Ti/Bi/C was deposited on Si substrate at room temperature by an electron gun in a high-vacuum deposition system. Carbon layer is deposited on top to avoid oxidation of the samples. Eighty mega electron volts Au ions and 100 MeV Ag ions with same value of Se for Ti are used for the irradiation of samples at the fluences 1 × 1013–1 × 1014 ions/cm2. Different techniques like Rutherford backscattering spectroscopy, atomic force microscopy and grazing incidence X-ray diffraction were used to characterize the pristine and irradiated samples. The mixing effect is explained in the framework of the thermal spike model. It has been found that the mixing rate is higher for low-velocity Au ions in comparison to high-velocity Ag ions. The result could be explained as due to less energy deposition in thermal spike by high-velocity ions.
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