Study on reducing the energy barrier between an electrode and an organic semiconductor by using inorganic semiconductor layer in organic thin film transistors

The surface of indium tin oxide (ITO) used as electrodes in organic thin film transistors (OTFTs) was coated with indium antimonide (InSb). In order to increase the work function of the ITO electrode, InSb was deposited by thermal evaporation on the surface of the ITO for 1, 2, and 3 seconds, at 600 degrees C at a deposition rate of 24 angstrom/sec. The changes in the work function of the ITO with the thin InSb layer were measured by using a Kelvin probe. A work function increase of 0.245 eV was observed in the ITO with the thin InSb layer. Through the process, the transmittance of the ITO with InSb was not changed. In addition, causes for the work function change of the ITO with thin InSb layer was analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), Atomic absorption spectrometry (AAS) and semiconductor parameter analyzer. In the electrical measurements, the energy barrier was reduced in the interface between the ITO and the organic layer (pentacene) in the OTFT. These results suggest that ITO with a thin TnSb layer increases the probability for high performance of OLEDs and OTFTs.