Theoretical Study Of The Electrical Conductivity Of Iodine Doping Polymer

In this paper, the issue of doping influence on the organic conducting polymers that have attracted concern over the past thirty years was investigated by means of density functional theory (DFT). We calculated the geometry structures and electronic properties of iodine doping polyacetylene and polypyrrole respectively. Through choosing the mode of action between dopant and polymer molecular chain and the corresponding polymer, the influnce on the conductivity of dopant to the organic conducting polymers was analyzed. The main researched content and results are listed following.In chapter1, we introduced the research progress, process of development, conductive mechanism, development tendency, application and design of organic conducting polymer. Based on excellent conductivity, well optical property, potential development prospect, organic conductive polymer materials have been studied and applied widely. Furthermore, the main content and significance of our research work were also introduced in this section.In chapter2, the computational methods of density functional theory (DFT), time-dependent density functional theory (TD-DFT) was introduced briefly.In chapter3, in order to explore the conductivity of iodine doping polyacetylene, we investigated the geometries and electronic properties of iodine doping the single, double and four chains of Polyacetylene (PA) including vertical and parallel mode. Using the density functional theory with the B3LYP method at the6-31G(d) level, except the iodine atom, we employed the standard LANL2DZ basis set. Comparing the change of BLA(Bond length alternation), Eg, and charges transfer in single and double chains with pure chains on B3LYP/6-31G*level, we found that double chains doping have more intensive influence. By analyzing the DOS, PDOS and absorption spectra, the interaction between iodine and polymer chain was illustrated, as well as the conductivity. The result of research on the frontier molecular orbit of single, double and four chains doped PA showed that the charges transfer from polymer chain to I2. Our work provided a theoretical foundation about I2doping PA.In chapter4, we investigated the geometries and electronic properties of iodine doping polypyrrole, using the density functional theory with the B3LYP method at the6-31G(d) level, except the iodine atom, for which we employed the standard LANL2DZ basis set. In the exploring of iodine doping polypyrrole, we considered the three forms of iodine I-, I3-and I2. There was only one mode when I" and I3-doped with polypyrrole respectively, but I2doping polypyrrole existed three modes. Comparing the stability of the above three doping modes, vertical and bifacial mode of I2doping polypyrrole was taken to the research mainly, the optimal doping ratio was I:P=1:2. With tetramer, six polymer and octamer as doping matrixes, comparing the BLA(Bond length alternation) and Eg of doping before and after, it illustrated that doping was able to have a significant affection the geometries and electronic properties of polypyrrole. By the analysis of frontier molecular orbit, DOS, PDOS and absorption spectra, the participation of iodine could change the electronic structure of polymer chain, and the conductivity of polypyrrole was effectively increased.Under the constant doping ratio, the Eg would decrease as well as the degree of polymerization was increased.