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Abstract :
[en] As the rarefaction of fossil energies, photovoltaic cells are certainly amongst the most important energy sources for the future. Our work concentrated on hybrid photovoltaic cells that are based on organic (polythiophene) and inorganic components (ZnO nanorods). The technology that maximizes the contact area between the two semi-conductor n and p while maintaining two separate components is the interdigital configuration.
As the inorganic part, perfectly well aligned zinc oxide (ZnO) 1D nanostructures have been synthesized by hydrothermal growth on ZnO-seeded FTO substrates. SEM, AFM and XRD characterizations evidence patterned well- aligned nanorods with high c-axis, their roughness of surface and the length of their nanostructure.
Concerning the organic component, we synthetize polythiophenes based diblock copolymer with high degree of regioregularity and predetermined molecular weight using Grignard Methatis (GRIM) process. Diblock polythiophene based copolymers are of interest because of the possibility of generating multifunctional materials (by associating the specific properties of each block), including their ability for self-assembly into well-defined nanostructures (fibrils or micelles) with controllable dimensions. Poly(3-hexylthiophene) (P3HT) composes the first block and the second block is either a polythiophene bearing an acrylate group on each monomer unit (PAcET), or a polythiophene bearing both acrylate and poly(ethylene glycol) side chains (P(AcET-co-PEGET)).
Typically, the acrylates are used to fixe in a covalent way the copolymer to ZnO nanorods, while the PEG grafts are necessary for the solubilisation of the copolymer in the electrografting medium. 1H NMR and DLS characterizations allow us to find the backbone and the micellar structure of the copolymer. Cathodic polarization (electrografting) of ZnO nanorods induces electropolymerization of acrylate groups, leading to an adherent organized film of poly(thiophene)-based micelles. During the illumination tests, we obtained a typical response of a photovoltaic despite the low yields.
This promising synthetic route opens exciting perspectives for the production and the electrochemical functionalization of different lengths of ZnO nanowires, which seems to be promising candidate for hybrids photovoltaic cells.
