Towards solution-processed ambipolar hybrid thin-film transistors based on ZnO nanoparticles and P3HT polymer

Abstract

Solution-processed n-channel oxide semiconductor thin-film transistors (TFTs) were fabricated using zinc oxide (ZnO) nanoparticles. Polycrystalline fused-ZnO nanoparticle films were produced by spin-coating ZnO nanosphere dispersions following by a subsequent heat treatment. The solution-processable semiconductor ink based on ZnO was prepared by dispersing the synthesized ZnO nanospheres in isopropanol mixed with ethanolamine to various concentrations from 20 to 80mg/mL. Such concentration dependence on morphology and microstructure of thin films was studied on spin-coated ZnO films by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Spin-coated ZnO films involved as active layers in transistor configuration delivered an almost ideal output characteristic (Id–Vd) with an electron mobility up to 3×10−2cm2/Vs. As a p-channel semiconductor, a poly(3-hexylthiophene) (P3HT) solution-processable ink was deposited by spin-coating on top of closely packed ZnO nanoparticles-based films to form an uniform overlying layer. A hybrid (inorganic–organic) interface was formed by the direct contact between ZnO and P3HT leading to carrier redistribution. Such solution-processed hybrid thin-film transistors delivered in air well balanced electron and hole mobilities as 3.9×10−5 and 2×10−5cm2/Vs, respectively.