Formation of solution-processed multistacked ferroelectric layers for performance improvement of ferroelectric-gated pentacene field-effect transistors

In solution-processes, the formation of multistacked layers (MSLs) is difficult because of natural dissolution and/or damage to the underlying film by the solvent used for the upper film. To form MSLs in solution-processes, using orthogonal solvents for each layer is a representative remedy. As the number of MSLs increases, the selection of appropriate solvents for every layer becomes harder. In this work, we report a viable method to form MSLs, even when using one material for the entire solution-process. We present that solution-processed MSLs can be formed by tuning the solubility by mixing an orthogonal solvent. We fabricated ferroelectric MSLs using a ferroelectric polymer and applied the MSLs into a ferroelectric-gated field-effect transistor. We obtained improvements in electrical properties such as current on/off ratio, subthreshold swing, and mobility in transistors with MSLs, in comparison to the single layer case.