Although its basic chemical
composition (–CH2–)n is simple, its semi-crystallinemorphology is
very complex, and thus charge injection at the electrodes and
transport through the volume are also complex processes. It is of
interest to note that crystalline polyethylene has a negative electron affinity, i.e. the bottom of the conduction band is approximately 1 eV above the vacuum level, and electron traps with
depths in the range 0–0.3 eV formed by the conformations of the
polymer chains themselves are to be expected in semi-crystalline
polyethylene [9–11].