Probing the Effect of Surface Modification of MgO Filler on Charge Transport in Polyethylene/MgO Composites: From an Electronic Structure Viewpoint

In this work, with the aid of first-principles calculation, we attempt to clarify whether nanoparticles itself can trap electrons and holes. Polyethylene (PE)/MgO nanocomposite is chosen as a model system. According to the computed adsorption energies, pristine and fully terminated surfaces are stable for the MgO (100) and MgO (111) surfaces, respectively. The electronic structures of several energetically favorable surface configurations are then studied. To probe the behavior of the excess charge, we examined the change in the charge distribution upon electron and hole doping. In the case of ideal MgO, holes are localized within the MgO slab, whereas electrons reside at the PE layer. We also show that the band alignment at the MgO/PE interface and, therefore, the carrier trapping property of MgO, is mainly determined by the intrinsic band edge positions of PE and MgO and the surface dipole of MgO, which can easily be tuned by surface modification.