Optical and electrical characterizations of poly(N-alkylcarbazole) light-emitting diodes. Interpretation of electrical behaviour

In this paper, fabrication technology and electrical and optical characterizations of poly(N-alkylcarbazole) (PACZ) light-emitting diodes are reported. The devices are indium—tin oxide (ITO)/PACZ/Al structures and emit blue light at about 470 nm. The influence of the active layer thickness and the temperature on J—V electrical characteristics are studied. The results are interpreted with theoretical models. The current is limited by hole carrier injection at the ITO/polymer contact. In the temperature range 291–393 K, the charge injection is mainly due to the emission—diffusion Richardson Schottky phenomenon. On the contrary, at low temperatures, a tunnelling effect is observed.