Zirconium oxide dielectric layer grown by a surface sol–gel method for low-voltage, hysteresis-free, and high-mobility polymer field effect transistors

•We fabricated zirconium oxide layer by the surface sol–gel method.•The fabricated ZrOx layer revealed good dielectric strength without additional treatment.•The PFET fabricated on ZrOx layer showed nearly hysteresis-free and high mobility characteristics.

A simple, facile surface sol–gel method is introduced for the fabrication of zirconium oxide films for use as a dielectric layer of a solution-processed polymer field effect transistor (PFET). High dielectric strength is demonstrated for a zirconium oxide layer under room-temperature fabrication conditions using a surface sol–gel method without any post-treatments, which are typically needed in general sol–gel methods. X-ray photoemission spectroscopy showed that the fabricated zirconium oxide layer consists of inorganic ZrO2 and organic alkoxide groups, which can explain its marginal dielectric constant (∼9) and continuous film properties. In addition, by finishing the surface sol–gel synthesis at the stage of chemisorption, the hydrophobic nature of the final surface was retained, leading to a trap-free semiconductor/dielectric interface. As a result, the PFET made with a conventional polymeric semiconductor rendered nearly hysteresis-free and high mobility (0.3 cm2/V) characteristics at low voltage (<2 V).

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