Internally less-ordered zinc oxide films enabled by polyvinylpyrrolidone for mobility enhancement in electrolyte-gated transistors

초록

Blending zinc oxide (ZnO) precursors with polyvinylpyrrolidone (PVPy) in a solution leads to the formation of surface-wrinkled but microscopically less-ordered thin films of oxide semiconductor with an enhanced electron mobility through a sol–gel reaction. The role of PVPy additives in ZnO was systematically investigated to elucidate the relationship between polymer incorporation and device characteristics. Pre-annealing at temperatures between the glass transition and decomposition temperatures of PVPy induced a wrinkled surface on the composite films. Subsequent post-annealing at 500 °C decomposed the polymer additives and facilitated densification of ZnO. Notably, thin films prepared with 10% of PVPy exhibited a lowest degree of ordering, without significant change in the Zn and O compositions or the optical bandgap energy. This morphological tuning in a microscopic scale resulted in a remarkable increase in the average mobility of electrons from 9.9 cm2 V−1 s−1 for pristine ZnO films to 19.2 cm2 V−1 s−1 for the ZnO:PVPy (10%) films in electrolyte-gated transistors. These findings highlight the critical role of polymer-assisted modification of microscopic morphology in enhancing the electrical performance of ZnO thin films, and suggest a simple approach for advancing solution-processed electronic devices based on amorphous oxide semiconductors.

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