LIGHT-EMITTING-DIODES USING QUINQUETHIOPHENE LANGMUIR-BLODGETT-FILMS - EFFECT OF ELECTRON-TRANSPORTING LAYERS

Langmuir-Blodgett (LB) films of quinquethiophene have been used as act ive emitting layers to fabricate light-emitting diodes. Green electrol uminescence was visible in a dark room. The effect of the thickness of the film on the electroluminescence efficiency has been investigated. Even 5 LB layers have been shown to yield the same luminance as thick er films. Additional LB films of electron- transporting material have been used to increase the quantum efficiency, which has also resulted in a lower ''turn-on'' current for the device. The electroluminescence spectrum showed a profile identical to the photoluminescence spectrum of quinquethiophene.