Although its basic chemical composition (–CH2–)n is simple, its semi-crystalline morphology 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].