Near-infrared light-emitting ambipolar organic field-effect transistors

The operation of an ambipolar light emitting organic field-effect- transistors (LEOFET) based on a solution-processable small-bandgap squarylium dye was demonstrated. Simultaneous injection of holes and electrons was obtained leading to ambipolar transistor operation because of the low energy gap of the dye and its favorable position relative to the Fermi level of both gold source and drain electrodes. The quantum efficiency of the device was found to depend only weakly on the position of the recombination zone along the channel. Infrared light emission was observed from within the electroactive transistor channel under appropriate bias conditions. Radiative recombination was confirmed by using electroluminescence (EL) measurements. Such a device configuration provides a powerful tool towards a better understanding of the various electronic processes within organic materials under different conditions.