Cellules solaires hybrides organiques-inorganiques sur support souple

Le but de ce travail a ete de developper des cellules a base d oxyde nanoporeux photosensibilise sur support plastique. Dans ce contexte, une nouvelle voie d elaboration de couches de nanoparticules d oxyde a basse temperature a ete developpee par irradiation ultraviolet sous air. Tout d abord, des couches de dioxyde de titane ont ete preparees par cette methode, les films obtenus etant constitues d un reseau mesoporeux de nanoparticules interconnectees de dioxyde de titane de structure anatase d apres les caracterisations effectuees par microscopie electronique a balayage, diffraction des rayons X, porosimetrie d adsorption d azote et d intrusion de mercure et analyse thermogravimetrique. Apres sensibilisation des couches par un complexe polypyridyle de ruthenium, les cellules photovoltaiques elaborees avec des films en contact avec un electrolyte liquide presentent des rendements de conversion energetique compris entre 1,6 et 2,5 % suivant la nature des particules utilisees. Cette voie a ensuite ete elargie a d autres oxydes tels que l oxyde de zinc et le dioxyde d etain ainsi qu a des oxydes en configuration coeur-ecorce . Les rendements obtenus avec le dioxyde d etain, 1,5 a 1,8%, sont tout a fait remarquables par rapport a ceux decrits dans la bibliographie pour des couches traitees a haute temperature. Les rendements plus eleves avec les couches traitees aux UV etant lies a une amelioration des tensions de circuit ouvert et des facteurs de forme, les phenomenes physiques regissant les performances de ces dispositifs ont ete etudies par differentes techniques, notamment la spectroscopie d impedance electrochimique et le declin de tension de circuit ouvert. Enfin, les performances electrochromes des films de dioxyde de titane traites aux UV ont ete caracterisees sur support verre et plastique en presence d un electrolyte liquide ionique, les efficacites de coloration etant comparables aux systemes elabores a haute temperature. This work aimed to develop dye-sensitized solar cells on plastic substrates. In this context, a new low-temperature method to make nanoporous oxide layers based on ultraviolet irradiation under air was studied. First of all, titanium dioxide layers were prepared with this method; the films obtained were composed of a mesoporous network of interconnected anatase titanium dioxide nanoparticles as evidenced by scanning electron microscopy, X-ray diffraction, nitrogen sorption and mercury porosimetries, and thermogravimetric analysis. After sensitizing the films with a ruthenium polypyridyl complex, the photovoltaic cells based on the films in contact with a liquid electrolyte gave conversion efficiencies between 1.6 and 2.5% depending on the nature of the particles used. This low-temperature method based on ultraviolet irradiation was then expanded to other oxides, such as zinc oxide and tin dioxide, as well as to core-shell structures. The conversion efficiencies obtained with tin dioxide were very high, i.e. 1.5 to 1.8%, compared to those usually reported in the literature for films sintered at high temperatures. The higher efficiencies obtained for the UV-treated films were related to higher open circuit potentials and higher fill factors. Therefore, the physical phenomena involved were investigated with various techniques; in particular, electrochemical impedance spectroscopy and open circuit voltage decay. Finally, the electrochromic performances of the low-temperature UV-processed nanoparticulate titanium dioxide films were studied on glass and plastic substrates with an ionic liquid. The coloration efficiencies were found to be comparable to those of high-temperature processed layers.