Theoretical Investigation Into The Thermoelectric Transport In DNA Molecules

Nanoscale materials have attracted more and more attention because of their excellent thermoelectric conversion efficiency, deep understanding and investigation on the thermoelectric transport behavior of nanoscale systems is not only helpful to optimize and improve the thermoelectric performance of electronic devices, but also has important significance for the design of novel quantum thermoelectric devices, furthermore, provides a theoretical basis for harvesting wasted heat and saving energy. The DNA molecule, as a natural organic molecule, plays an outstanding role in molecular electronics due to its unique self-assembly and self-recognition characteristics. What’s more, the DNA molecule has a double helix spital structure, and the chiral feature of the DNA molecule will induce the spin selectivity in the electronic transport. Therefore, the further research on the spin dependent thermoelectric transport through DNA molecules can offer a new idea for the design of spin-based thermoelectric devices.In the first chapter, we introduce the thermoelectric effect and the researchful advances of spin caloritronics in detail. In the second chapter, we firstly introduce the biological, physical and chemical properties of DNA molecules, and then introduce the main methods and the corresponding researchful progress of the electron transport through DNA molecules. In this thesis, the following works have been carried out on the thermoelectric transport of chiral DNA molecules:1. The thermoelectric transport properties of ferromagnetic metal dsDNA ferromagnetic metal are studied by emplying the non-equilibrium Green’s function method. We can obtain the large thermoelectric conversion efficiency and realize the pure spin Seebeck effect by adjusting the temperature, spin-orbit coupling strength, helix angle and other system parameters. It is found that the spin-orbit coupling and helix angle can enhance the spin Seebeck coefficient, and the intrachain hopping integral can not only regulate the thermoelectric coefficient, but also determine the type of the carriers.2. Using the non-equilibrium Green’s function method and the Landauer-B ¨uttiker formula, the thermal spin effect of the normal metal dsDNA ferromagnetic electrode junction driven by thermal bias is investigated. We can observe the thermoelectric diode effect, the spin-Seebeck diode effect and the negative differential thermal resistance in current-thermal bias curves. Using gate voltages to control the system,the pure spin-current transport can be realized, and physical mechanisms on the influence of system parameters(such as helix angle, spin-orbit coupling interaction, spin polarization, etc.) on the current are presented.Finally, a summary and some outlooks of this thesis are presented in Chap.5.