A polythiophen derivative was synthesized as an light-emitting layer of LED

and its electroluminescent properties have been investigated under low and superlow temperature.The energy gap is about 2.04eV

the peak of photoluminescent spectrum is at 630nm and the emitting intensity is higher for this compound.The diode began to emit at 18V when it was in liquid nitrogen

ITO as a positive electrode

the metals as negative one (the ratio of Mg and In is 10 to 1).The intensity increases rapidly with increasing voltage and it is clear enough to be visible when the applied voltage is higher than 20V.The diode also possesses better rectification because there was no electric current when a reverse voltage was applied.It gives a red emission peaked at about 687nm.Although the diode can give red emission at room temperature in vacuum and the wavelength is still 687nm

and the applied voltage is much lower than that in liquid nitrogen

it begins to light when the voltage is 6V. The above results reveal that the plolythiophen appears some good electroluminescent properties either at room temperature or at low temperature.The studies are significant for studing the electroluminescent properties of organic high polymers

especially at low temperature.