International audienceWe investigated the effect of a CuI anode buffer layer (ABL) on the molecular orientation of the copper phthalocyanine (CuPc) in organic photovoltaic cells (OPV cells), and we compare it to the effect of MoO3 buffer layer. While, in the presence of CuI, the CuPc molecules lie down parallel to the substrate, they stand up perpendicular in the case of MoO3. We show that the optical absorption, the morphology, and the J-V characteristics of the OPV cells depends strongly on the orientation of the CuPc molecules. The improvement of the OPV cells performance is related to the property modifications induced by the change in molecule orientation. We show that the improvement of the OPV cell performance through the templating effect of CuI depends strongly on the deposition rate of the CuI, because the CuI thin-film morphology depends on this deposition rate. In this context, we show that the use of a double-ABL MoO3/CuI leads to a significant improvement of the cell performance. These results are discussed on the basis of the dual function of MoO3 and CuI. While both of them reduce the hole-injection barrier, CuI improves the CuPc film absorbance through specific molecular order and MoO3 prevents the OPV cells from leakage-path formation

Organic photovoltaic cells using polymer belonging to the aniline-heteroaryl family as electron donor have been achieved by thermal evaporation. We show that the properties of the polymer film, morphology, molecule order and conductivity depend strongly on the bottom anode buffer layer. While cells without anode buffer layer or with MoO 3 or CuI anode buffer layer have been probed, we show that CuI allows improving strongly the cells efficiency through an improvement of the morphology and conductivity of the polymer film. This shows that although it is necessary a good band matching at the interface, this is not sufficient, because the templating effect of CuI on the polymer film is primordial for photovoltaic cells improvement.

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The present work deals with copolymers synthesized by reacting aniline units or blocks with 2,6-di(thiophen-2-yl)aniline and 2,2'-(thiophen-2,5-diyl)dianiline monomers. Characterization by spectroscopic techniques such as FT-IR, UV-vis, 1H-NMR corroborated the formation of true copolymers. Synthesized products showed improved solubility and better photovoltaic efficiency than the respective homopolymers. The latter is due to the presence of a greater number of quinoid units, capable of promoting charge carriers generation. However, the low mobility of the charge carriers, that increases copolymers resistivity, would be responsible for an efficiency improvement of just one order of magnitude with respect to the homopolymers.

A new series of polymers obtained from 3 0 -alkyl-terthiophene monomers have been electropolymerized aimed at using them as raw materials for the development of electronic devices, e.g., solar cell and organic light-emitting diodes, among others. The polymers were characterized by infrared and UV-Vis spectroscopy and cyclic voltammetry. Cyclic voltammetry results revealed that during polymerization both terthiophene system and substituent groups are oxidized, but these processes are reversible. The products were tested in solar cells and the maximum yield obtained was 0.01%.