Langmuir-Blodgett (LB) films of quinquethiophene have been used as active emitting layers to fabricate light-emitting diodes. Green electroluminescence 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 thicker 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.