Optical studies of electric fields in poly(2-methoxy-5-ethyl(2(\u27)-hexyloxy) para-phenylene vinylene) light-emitting diodes

摘要

We report electroabsorption studies of poly(2-methoxy-5-ethyl(2(\u27)-hexyloxy) para-phenylene vinylene) light-emitting diodes. An electric field develops during operation which opposes the field of the applied bias. The counter field builds up within 5 s of turning on the device, increases in magnitude with the operating voltage, and decays exponentially with a time constant between 15 and 32 s. We attribute the counter field to bulk carrier traps and discuss its relevance to the increase of the turn-on voltage as organic light-emitting diodes degrade. (c) 1999 American Institute of Physics. [S0003-6951(99)01224-3].