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Recently, experimental results have shown that photovoltaic properties of Fullerene (C60)/ Phthalocyanine based devices improve considerably as molecular orientation is changed from edge-on to face-on. In this work, we have studied the impact of molecular orientation on C60/ZnPc interfacial properties, particularly focusing on experimentally observed face-on and edge-on configuration, using density functional theory based simulations. The results show that the interfacial electronic properties are strongly anisotropic: direction of charge transfer and interface dipole fluctuates as molecular orientation is switched. As a result of orientation dependant interface dipole, difference between acceptor LUMO and donor HOMO increases as the orientation is changed from edge-on to face-on, suggesting a consequent increase in open circuit voltage (VOC). Moreover, adsorption and electronic properties indicate that the interfacial interactions are much stronger in the face-on configuration which should further facilitate the charge-separation process. These findings elucidate the energy level alignment at C60/ZnPc interface and help to identify interface dipole as the origin of the orientation dependence of VOC. [ABSTRACT FROM AUTHOR]

We have investigated the C60/ZnPc interfacial properties in face-on orientation by using van der Waals (vdW)-corrected density functional theory (DFT) techniques. These findings show that different vdW approaches qualitatively provide a similar description of ZnPc adsorption on C60. Adsorption of ZnPc on C60 leads to the formation of an interface dipole. The magnitudes of charge transfer and interface dipole are found to be sensitive to the vdW method employed. These results suggest that C60/ZnPc interface dipole originates mainly as a result of charge transfer instead of adsorption induced charge re-arrangement. [ABSTRACT FROM AUTHOR]

Abstract: The perovskite based SrFeO3 and SrFe0.5Nb0.5O3 materials have been synthesized by solid state reaction methods. The structural properties are investigated using a combination of X-ray diffraction and X-ray absorption fine structure spectroscopic techniques. From the Rietveld refinement of the X-ray diffraction data it has been observed that SrFeO3 has a simple cubic perovskite structure, which is consistent with the previous literature results; whereas SrFe0.5Nb0.5O3 shows a tetragonal structure within P4mm space group. X-ray absorption results demonstrate that the valence state of Fe in SrFeO3 is (IV); however, it changes to (III) when 50% Nb5+ is substituted at the Fe sites. [Copyright &y& Elsevier]

Abstract: Polyaniline (PANI) was doped with dodecylbenzene sulfonic acid (DBSA) and then mixed with PVC by solution blending method to prepare DBSA doped PANI (PAND)/PVC composites. FTIR spectroscopy indicates the strong dipole–dipole interaction between the individual components of the composites. The ac electrical properties of the synthesized composites were investigated by complex impedance spectroscopy in the frequency range of 0.5–106 Hz at room temperature. Both dielectric loss factor and permittivity increase with the decrease of frequency exhibiting strong interfacial polarization at low frequency. Addition of PAND in PVC reduces the charge trapping centers by increasing the number of conducting channels participating in the relaxation process; hence an increase in conductivity is observed. [Copyright &y& Elsevier]

The crystal properties of pure and doped scheelite (ZrSiO4) have been investigated by employing the computer simulation techniques. The potential parameters used in the present study can reproduce the crystal structure, having good agreement between calculated and experimental data. Solution energies are calculated for mono-, di-, tri- and tetravalent dopants to ascertain the site occupied by the dopant ion in the host lattice. These calculations suggest that all dopant cations substitute at the Zr sites except Al, which prefer to substitute at the Si sites. We also present a comparative study between the scheelite and zircon phases of ZrSiO4. [Copyright &y& Elsevier]