The thermoelectric characteristics of materials and molecular devices have garnered significant scholarly interest, as they offer the potential to transform surplus thermal energy into electrical energy. This dissertation delineates a comprehensive series of investigations into the electronic and thermoelectric characteristics of diverse families of molecular junctions comprising metallo-porphyrins. The theoretical framework will encompass two principal methodologies; Density Functional Theory, operationalized within the SIESTA code, and the Green’s function formalism for electron transport (Chapter 2), which is executed in the GOLLUM code. Both methodologies are employed extensively to analyze a particular family of metallo-porphyrin molecules. In this thesis, I cover a set of key results main results in the areas of electrical and thermoelectric properties of metallo-porphyrins molecular wires, in the third chapter, our study included a comparison of the electrical and thermoelectric characteristics of five zinc porphyrin configurations. The results show that changing the linker between zinc diner units has an essential effect on the electrical conductance and thermopower values of these structures. Consequently, the thermoelectric figure of merit ZT will change which means the thermoelectric efficiency change.We also observed a notable augmentation in the Seebeck coefficient when the linker connecting the Zinc porphyrin dimers is either (C - N) or (C - C). The augment in the Seebeck coefficient can be ascribed to a variety of factors. One plausible reason for this phenomenon is the dissimilarity in the electronic structure and energy levels between the zinc porphyrin molecule and the carbon-hydrogen linker. In the fourth chapter, the thermoelectric properties of five zinc porphyrin dimers (ZnP) were investigated. Here, we introduce a theoretical analyses of electron transport across a Zn-porphyrin dimer molecule sandwiched between gold electrodes with five different distinct connections. This work contributes to understanding what occurs when the linker between zinc porphyrin dimers exists and the effect of the linker's type, position, number on the electrical and thermoelectric properties of Zn-porphyrin dimer. The results show that moving from direct to linker contact will significantly decrease electrical and thermal conductance. In addition, changing the position and the number of linkers will lead to a decrease in electrical and thermal conductivity and also a decrease in the thermopower S. Clearly, the changing of the contact linker point and the number of linkers between zinc porphyrin dimers have an essential role in electric and thermal properties. In Chapter Five Our results demonstrate that the electronic transport and thermoelectric properties of these junctions can be significantly improved in the presence of another dimer. Since by adding a new zinc porphyrin dimer the electrical conductance G increased up to an order of magnitude as well as, Further enhancement in the Seebeck coefficient for a good range of Fermi energies. In contrast, in structure zinc porphyrin dimer without any additives.
