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International audience; Novel organic thiophene derivatives, (E)-Bis-1,2-(5,500-Dimethyl-(2,20:30,200-terthiophene)vinylene (BSTV) and (E)-Bis-1,2-(5,500-Dimethyl-(2,20:30,200:30,2000-tetrathiophene)vinylene (BOTV), with different numbers of thiophene units, have been synthesized. They are introduced into organic photovoltaic cells as electron donor. The both organic photovoltaic cell configurations are probed: classical, i.e. with the ITO used as anode, and inverted, i.e. with ITO used as cathode. Whatever the cell configuration, the best results are obtained when a double cathode buffer layer Alq3/Ca is used. Actually, such double cathode buffer layer allows cumulating the advantages of its both constituents. The Alq3 blocks the excitons and protects the organic electron acceptor from cathode diffusion during its deposition, while the low work function of Ca induces a good band matching at the interface electron acceptor/cathode. On the other hand, it is shown that the organic layer surface morphology is decisive whatever the cell efficiency. While the BSTV layers are homogeneous those of BOTV are not. It follows that, in the case of classical organic photovoltaic cells, leakage currents limits the performances of the cells using BOTV, and better performances are obtained with BSTV. This difficulty is overcome in the case of inverted organic photovoltaic cells. This configuration allows limiting the effect of the inhomogeneities of the donor layer and better efficiencies are obtained with BOTV, which was expected due to its smaller band gap value.

When HDPE is added to SBR, the melt elasticity of the system gets reduced. The morphology of the extrudates of the blends has been found to be dependent on the shear rate. Dynamic crosslinking with DCP has been improved the processability of SBR/HDPE blends by reducing the melt elasticity of the system considerably.

Polyaniline -Polyisoprene composites were prepared by chemical method. The Polyaniline particles were of nanometer size. The characterization of the PANI-Polyisoprene composite were done by UV-visible spectrometer, Dynamic light scattering and Keithly source meter. The size of the polyaniline particles was found to be 23.29 nm. The electrical properties of the sandwich structure using ITO-Polyisoprene-PANI-Al indicated that the composite can find application in microelectronics.

Iodine doped natural rubber attracted a great deal of interest in the processing of developing low cost, light weight and flexible photovoltaic device. In this work, we fabricated device by sandwiching Iodine doped cis-1,4 polyisoprene (Natural rubber) as an active layer between two different work function electrodes aluminium and Indium Tin Oxide (ITO). Electrical properties were analyzed by using current-voltage (I-V) measurements. It showed a typical diode behavior similar to the conventional diode. Dielectric constant and the density of states closed to the Fermi level of the material were calculated by using the step-by-step method based on the space-charge-limited-current model.