Electroluminescence phenomena of low density polyethylene film under applied ac voltage

Electroluminescence excitation mechanisms have been investigated in a low-density polyethylene film under an applied ac electrical field. The principle of phase resolved electroluminescence measurement using a charge coupled device camera is outlined in this paper. Experimental results from several tested samples have shown that the samples can be divided into two different groups according to the emission spatial distribution: (1) homogeneous and (2) localised spots superimposed on a homogeneous emission. At the same applied voltage, the homogeneous and localised spots EL spectral resolutions have maximum light emitted from the near infra red and visible regions respectively. This suggests that space charge on a localised surface area might induce a divergent field and transfer the charge into deep traps at an appropriate voltage amplitude.