Push-pull ZnII-porphyrin, meso-substituted with a benzodithiophene spacer, as promising sensitizer in Dye-sensitized solar cell

Dye-sensitized solar cells (DSSCs) represent today an interesting class of photovoltaic devices because of their excellent light-to-electricity conversion efficiencies. Many dyes have been investigated and among them the ruthenium sensitizers have shown the best results reaching more than 11% efficiency [1]. It was recently reported the achievement of an 11% efficiency with a push-pull meso-substituted ZnII-porphyrin as dye [2]. Here we present the synthesis of a push-pull ZnII-porphyrin with a N,N-dimethylaniline donor group and a carboxy acid acceptor group with a new benzo[1,2-b;4,5-b’]dithiophene spacer. The orthofused aromatic/thiophene system shows a rigid π-conjugated-condensed framework, free from configurational disorder, which leads to unique electronic properties such as conductivity, high field effect mobility and tunable stacking in the solid state relevant for applications such as in LED, FET and organic solar cells [3]. It may play a relevant electronic role in favoring electron transfer along the push-pull system. Theoretical TD-DFT calculations, electrochemical and photoelectrochemical studies, and a compared investigation of the light-to-electricity conversion efficiency in a dye-sensitized solar cell will be presented. [1] M. Nazeeruddin, F. De Angelis, S. Fantacci, A. Selloni, G. Viscardi, P. Liska, S. Ito, B. Takeru, M. Grätzel, J. Am. Chem. Soc., 127, 2005, 16835. [2] T. Bessho, S. M. Zakeeruddin, C.-Y. Yeh, E. W.-G. Diau, M. Grätzel, Angew. Chem. Int. Ed., 47, 2010, 6646. [3] U. Giovanella, C. Botta, A. Bossi, E. Licandro, S. Maiorana, J. Appl. Phys., 100, 2006, 083107/1.