Highly Stable Flexible Thin-Film Transistors in Harsh Environments by Superhydrophobic Passivations

Nontoxic superhydrophobic passivation layers (PVLs) based on octadecylamine (ODA) and polydimethylsiloxane (PDMS) mixtures are prepared to improve the stability of InSnZnO (ITZO) thin-film transistors (TFTs) in harsh wet environments. After the passivation, the electrical properties of ITZO TFTs are partially improved for the interfacial dipoles between the ITZO films and the PVLs. Moreover, the PVLs effectively inhibit the contact and adsorption of water molecules on the surface attributed to their superhydrophobicity. Thus, the passivated devices exhibit stable electrical performance in extreme environments, including long-term positive bias stress (PBS) in the humid atmosphere, long-term water immersion, and strong acid/alkaline conditions. In addition, the superhydrophobic PVLs maintain the superhydrophobicity under 10000 bending cycles with a low bending radius, and the electrical characteristics of the passivated devices exhibit negligible degradation. This indicates that the superhydrophobic PVLs are suitable to prepare flexible oxide TFTs with high reliability.