M. Sampietro et al., Electrical characteristics of light-emitting electrochemical cells based on a wide bandgap polymer, PHYS REV B, 61(1), 2000, pp. 266-271
We report on the electrical characteristics of light-emitting electrochemic
al cells based on a methyl substituted ladder-type poly(paraphenylene) (m-L
PPP). Current-voltage (I-V) characteristics and capacitance-voltage (C-V) p
lots are used to track the formation of the highly conductive contacts, the
initial diffusive carrier transport regime, the onset of a net voltage dro
p across the polymeric bulk, and the final resistive behavior of the device
in which carriers are mostly driven by drift. The analysis of the C-V plot
s reveals a strong increase of the capacitance at the threshold as a signat
ure of the large carrier injection through the contacts and their diffusion
through the active layer. From the physical analysis of the device behavio
r an electrical model is drawn.