Résumé
Among renewable energies, the sunlight has by far the highest theoretical potential to meet theworldwide need in energy. Photovoltaic devices are thus currently the subject of intense research forlow-cost conversion of sunlight into electrical power. In particular, organic photovoltaics have emergedas an interesting alternative to produce electricity due to their low manufacturing cost compared tosilicon solar cells, their mechanical flexibility and the versatility of the possible chemical structures. Inthis dissertation, we focused our research on the development of new organic -conjugated materialsfor organic solar cells applications. Two types of solar cells have been studied during this work: bulkheterojunction and dye-sensitized solar cells. The charge transfer leading to the photocurrent is usuallybased on (i) a polymer donor and a fullerene acceptor in BHJ solar cells, such as the widely studiedpoly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) materials and (ii) ametal oxide (titanium oxide) sensitized with a dye and an electrolyte in DSSCs. Despite power conversionefficiencies have reached 5 and 13 % respectively for these two types of devices, they still display severaldrawbacks that limit their commercialization. P3HT displays a narrow absorption of the solar spectrumthus limiting the conversion efficiency. To overcome this limitation, we combined P3HT withchromophores, i.e. porphyrins, having an extending absorption. Then, to ensure better charge transferand extraction within the device, a cathode interfacial layer based on cationic -conjugatedpolyelectrolytes was added, Finally, dyes extracted from the biomass (chlorophyll derivatives) weresynthesized to replace the expensive ruthenium dyes in DSSCs. Since liquid electrolytes are volatile andcorrosive, which considerably limit the DSSCs stability, solid polymer electrolytes were also developed asan alternative.