Funzionalizzazione di nanotubi di carbonio con derivati tienilici per applicazioni fotovoltaiche

The attention to environmental issues has risen in recent years due to the increasing global demand for energy and the decreasing availability of fossil fuels. Therefore during this period there has been a significant development of technologies based on the direct conversion of solar energy into electricity using photovoltaic cells. Mention goes particularly to those based on organic materials, those with high e_ciency especially based on BHJ between a fullerene derivative (PCBM) and a conjugated polymer (P3HT) in the active layer of the cell. In this thesis we properly functionalized Single-Walled Carbon Nanotubes (SWNT) to verify the possibility to replace or complement the PCBM in organic solar cells with these functionalized materials. Using SWNT allows to exploit their exceptional electronic and thermal properties, but they need to be soluble in the solvents used for the deposition of thin films of the active layer of the cell. This objective can be achieved through the functionalization of SWNTs, e.g. by the reaction with an in situ generated diazonium salt to obtain derivatives of SWNT with high solubility. In this work we discuss the approaches followed for the synthesis of compounds with thiophene-based residues suitable to be used as precursors to the functionalization of SWNTs. The comparison between the thermal and electronic properties among the various samples of SWNT derivatized in batch and in continuous flow has shown to be interesting and remarks the necessity to find a compromise between solubility and functionalization degree to obtain a soluble derivative able to electronically interact with the matrix of P3HT. Thanks to the collaboration with the University of Palermo through the Solis project it has been possible to present the results of a study of fluorescence quenching of a matrix of P3HT by some derivatives of SWNT obtained in the course of this Thesis. For each sample we checked any electronic interaction with the polymer. Subsequentlywecarried out the derivatization of a sample of double-walled xix ABSTRACT nanotubes (DWNT) in order to verify the possibility of selectively functionalize the outer wall of the nanostructure while maintaining the electronic structure of the inner wall. Finally we synthesized derivatives ofSWNTappropriate for the subsequent growth of polymers covalently anchored to the nanotubes, in order to maximize the contact area between the two components