Density functional theory analysis of the effect of iodine in polyethylene

The interaction between iodine and polyethylene has been studied through the use of density functional theory (DFT) with the purpose of explaining the physical basis behind the increase in the conductivity of polyethylene upon doping with iodine. The interaction between polyethylene and various I
_n
stable configurations is characterized in terms of binding energy, bond lengths, electron charge density, changes in electron charge density, and mixing of atomic orbitals, all of which are determined through DFT. Based on the energy of iodine impurity states introduced into the bandgap and the spatial features of the impurity state wavefunctions, a mechanism by which iodine increases the conductivity of polyethylene is proposed. The mechanism explains the experimentally observed increase in hole mobility and decrease of activation energy of polyethylene upon doping with iodine.