Dinitrophenyl-hydrazone a, w-substituted oligothiophenes. Electrochemistry and Optics of Thin Films

The design and synthesis of active materials for organic photovoltaic cells (OPV) is a focus of considerable current interest motivated by the possibility of producing solar electricity using light-weight, cost-effective and environmentally friendly solar cells [1]. The hetero-junction generated by contacting an electron donor material (D) with an electron acceptor (A) is the heart of an OPV cell [2]. Donor-acceptor molecules built by connecting a diphenylhydrazone block to a dicyanovinyl acceptor group via various thiophene-based ?-conjugating spacers revealed to be promising materials for OPV applications [3]. The introduction in the D-A systems of nitro groups as acceptors, is still poorly studied. Such groups are characterized by a strong polar nature which can impart unique properties to the compounds. Here we explore novel dinitrophenyl-hydrazone ????-substituted 3-dodecyl-thiophene (NTN) and 3,3-dihexyl-terthiophene (NT3N) (Scheme 1). In these compounds two terminal dinitrophenyl-hydrazone moieties are acceptors (A) vs the central oligothiophene donor (D), in a conjugated A-D-A structure. The Electrochemical and Optical properties of the two compound in solution and in thin film will be analyzed and discussed.