The Electronic Structure In Real Coordinate Space And Electron Transport In Polymer

Early as 70's in 20 centuries beginning, Heeger, Macdiam and shirakawa have ever discoved that the conductivity of trans-polyacetylene can be greatly enhanced by tens of magnitudes by doping. Compared with the traditional of inorganic semiconductors, organic materials have strong interaction between electrons and lattices, lattice distortions can be induced by injected charges or photoexcitations, and inversely the distortions will impact on the electronic structure of the system. The charge carriers in polymers are self-trapped excitations, e.g., solitons and polarons, rather than electrons or holes. Thereafter, great interests have been attracted into the study of conducting polymer. A new academics-conducted electricity was born.In the subsequent research, a series of polymer materials have been discovered. As a new species of functional materials, conducting polymers hold general properties of polymers, such as easy processibility, flexibility, and low cost, as well as similar electronic properties of metals or semiconductors. Therefore, conducting polymers have greatly focused on in recent years by researchers. Furthermore, as polymers are typical samples of soft condensed matter, the understanding of organic and life materials has also been enhanced by the extensive study of polymers.The current researches on excitations in polymers are mainly based on the TLM and SSH model. The electronic structure and optical properties of polymers were then successfully studied by Su, Schrieffer and Heeger by advanced the concepts of soliton and polaron . Then after, extended SSH models were founded separately by Bishop, Sun, Conwell, Xie, et al., to study different kinds of excitations and their dynamical evolution processes. These work play important roles in the microcosmic understanding of conjugated polymers.With the technology of MBE and MOCVD ,the modern instrument of semiconductors have been advanced. The problems of electrons tunnel is the foundation of semiconductors parts.So it is important to study the unique conduct mechanism of polymers.In this thesis, a Hamiltonian for one-dimensional conducting polymers is founded based on the Kronig-Penny square potential well model. The total energy of the system is the functional of lattice site displacements treated as slight fluctuations by perturbation theory. The properties of different excitations of degenerate and nondegenerate conducting polymers, such as the electronic structure, the charge density and the lattice configurations, are simulated and compared with results from the SSH model in order to propose new method in studying polymers and obtain universal results. The results of the study are mainly as follows:1. Elementary excitations in the degenerate polymer trans-polyacetylene are studied by using the Kronig-Penny model . we have studed the form of lattices. .eigenvalues of ground-state and excitations.2.By use of transfer-matrix, calculated the transmission of one-dimension polymer.3. Compared the transmission between of pured and the doped polymer.4. Studed the relation between the ineraction of electron-lattice and transmission.