Portland State University. Department of Chemistry
Carl C. Wamser
Term of Graduation
Date of Publication
Master of Science (M.S.) in Chemistry
Porphyrins -- Synthesis, Photosensitizing compounds, Solar cells
1 online resource (v, 107 pages)
Solar light is the most important source of regenerative energy and represents mankind's only inexhaustible energy source. One of today's most promising tools to make use of solar energy is its direct conversion into electrical energy in a photovoltaic cell. The practical use of these solar cells depends on the price of the devices and therefore of the obtained energy. The conventional silicon cells, although efficient, are expensive for common consumer applications. The Grätzel cell is a photovoltaic system for harvesting the sun's energy that operates at about 10-15% overall efficiency, like a conventional solar cell, but does it at one-fifth the cost of conventional solar cells. However, the presence of the highly corrosive electrolyte, containing iodide and triiodide, hampers the incorporation of a highly conducting metallic grid and requires hermetic sealing of the module in order to prevent evaporation of the solvent as well as intrusion of water and oxygen. Also the degradation of the photon energy is substantial in such a solar cell. Our goal is to replace the liquid-phase redox relay in such cells with a conductive polymer covalently bound to a porphyrin photosensitizer. Porphyrins with carboxylic acid functional groups as active sites for linkage of the porphyrin to TiO2 and aminophenyl groups as sites for initiation of polyaniline growth or for anchoring a formed polyaniline chain are therefore the desired photosensitizers for our proposed solid-state solar cell.
An unsymmetrical porphyrin, 5,10,15-tri-[4-(carbomethoxy)phenyl]-20- [(4-acetamido)phenyl]porphyrin (TCM3AAPP), with two different types of substituents around the porphyrin periphery, has been synthesized by a mixed aldehyde condensation with pyrrole in propionic acid. TCM3AAPP was separated chromatographically from a mixture of six porphyrins formed by the reaction. The desired functional porphyrin 5, 10, 15-tri-( 4-carboxyphenyl)-20-( 4- aminophenyl)porphyrin (TC3APP), which will be used as a photosensitizer on the proposed solid-state solar cell, was obtained by cleaving off protecting groups from TCM3AAPP. Reaction conditions for synthesis of the parent porphyrin have been optimized by HPLC analysis. The desired porphyrin TC3APP has been identified by NMR and mass spectra and characterized by UV-visible and fluorescence spectra. Attempted synthetic methods for TCPP-T APP dyad are also presented in this thesis.
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Zhao, Yinping, "Syntheses and Characterizations of Unsymmetrical Porphyrins as Photosensitizers for a Solid-State Solar Cell" (1997). Dissertations and Theses. Paper 6287.