Synthesis and Photovoltaic Properties of Novel Porphyrin Derivatives

The porphyrin derivatives, 5,10,15,20-tetra(4-(N-pentane-carboxamide) phenyl) porphyrin (4NC5-TPP), 5,10,15,20-tetra(4-(N-dodecane-carboxamide) phenyl) porphyrin (4NC12-TPP) and their zinc-complexes (4NC5-TPPZn and 4NC12-TPPZn), have been synthesized. Their thermal properties and morphologies were investigated via thermal gravity analysis (TGA), differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that the 4NC5-TPP was amorphous and the 4NC5-TPPZn was crystalline at room temperature, while the 4NC12-TPP formed the columnar liquid crystal and the 4NC12-TPPZn showed the spherulite texture. The electron state density distributions and the optimum configuration of the porphyrin derivatives were calculated by chemical simulation. The electrochemical oxidation and reduction abilities of the porphyrin derivatives were studied by cyclic voltammetry (CV). It was indicated that the porphyrin derivatives had the potential to develop organic photovoltaic (OPV) devices. Using the porphyrin derivatives as donor materials and the 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) as the acceptor material, the OPV devices were fabricated. The device structure is ITO/porphyrin derivatives:PTCDA/Al. The relationship between the morphology and performance of OPV was studied. It was found that the crystalline morphology of the film was beneficial to improve the efficiency of the devices.