Observation of electron injection into organic field-effect transistor with au electrodes using electroluminescence under AC electric field

The electroluminescence (EL) from a tetracene field-effect transistor was examined by applying an AC voltage to elucidate electron injection from the source and drain An electrodes. The EL intensity was proportional to the AC frequency up to 500kHz, but it decayed rapidly with elapsed time when applying the AC voltage. The EL spectrum corresponded well with the photoluminescence spectrum. These results indicate that holes and electrons are injected into the tetracene alternately in accordance with the AC applied voltage, and that the EL is radiated due to the recombination of the injected holes and electrons, while the space charge formation leading to the gradual decay of the EL proceeds owing to the accumulation and trapping of excessive injected carriers.