International audienceAn original surface passivation technique of indium tin oxide (ITO) used as anode in organic solar cells is proposed. We demonstrate that a thin MoO3 film (3.5 +/- 1 nm) at the interface ITO/organic donor allows improving significantly the devices' performances. The devices are based on the multiheterojunction structure copper phthalocyanine (CuPc)/fullerene (C-60)/aluminum tris(8-hydroxyquinoline) (Alq(3)). The deposition of MoO3 onto ITO improves the charge transfer from CuPc to ITO. The enhancement in the hole collection efficiency in the presence of an oxide layer can be explained in terms of the reduction in the effective barrier against hole transfer from CuPc into the ITO anode. The contact ITO/MoO3/CuPc behaves like a metal-insulator-semiconductor (MIS) structure, which allows reducing the energy barrier due to the difference between the work function of ITO and the highest occupied molecular orbital of CuPc. It is shown that the optimum MoO3 thickness corresponds to a compromise between an optimum ITO coverage and a sufficient transparency of the trapezoidal barrier for the tunneling of the charge carriers. The MoO3 thin films are discontinuous, and the passivation effect is improved when the oxide thin film is covered by an ultrathin gold film. Such behavior is discussed in the light of band scheme structures after contact and of geometrical considerations

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This research reports the facile, controlled, low-cost fabrication, and evaluation of properties of polyaniline matrix deposited on titanium dioxide and copper(II) oxide ternary-composite (PANI@TiO2–CuO)-based electrode material for supercapacitor application. The process involves the preparation of CuO in the presence of TiO2 to form TiO2–CuO by a facile method, followed by in-situ oxidative polymerization of aniline monomer. The structural and physical properties were evaluated based on the results of FTIR spectroscopy, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), transmission electron (TEM) and scanning electron (SEM) microscopy, thermogravimetric analysis (TGA), and BET surface areas analysis. The results indicated that TiO2–CuO was dispersed uniformly in the PANI matrix. Owing to such dispersion of TiO2–CuO, the PANI@TiO2–CuO material exhibits dramatic improvements on thermal stability in comparison with the pure PANI. The cyclic voltammetry (CV) confirms the reversibility of PANI redox transitions for this optimized electrode material. Moreover, the results reveal that the specific capacitance of PANI@TiO2–CuO reaches 87.5% retention after 1500 cycles under 1.0 A g−1, with a better charge storage performance as compared to pure PANI and PANI@TiO2 electrodes. The preparation of PANI@TiO2–CuO with enhanced electrochemical properties provides a feasible route for promoting its applications in supercapacitors.

Different properties such as the structural, elastic, thermal, electronic, magnetic as well as the Curie temperature and the formation energy of the cubic perovskites PrXO 3 compounds (X = V, Cr, Mn, and Fe) are studied by using the density functional theory based on the full-potential linearized augmented plane wave with local orbitals method with the generalized gradient approximation (GGA) for the exchange correlation potential as applied in WIEN2k code. The GGA + U approximation is also used to treat the f-states of Pr atoms and d-states of X atoms. We have also applied the analytical techniques for the structural parameters. The calculated structural parameters by both methods are in good agreement with experimental results. The calculated critical radii of the compounds exhibit ion conductivity as well as oxygen migration. The PrVO 3 , PrCrO 3 and PrFeO 3 compounds have a ductile nature, while PrMnO 3 is brittle. The calculated electronic properties reveal the metallic nature for the studied compounds. Double cell optimizations, density of states as well as magnetic moment confirm that these compounds are ferromagnetic metals. The negative value of formation energy confirms the stability of these compounds. Large and small values of Curie temperature in these compounds show strong and weak interaction among the magnetic atoms, respectively.