Paper Transistors with Organic Ferroelectric P(VDF-TrFE) Thin Films Using a Solution Processing Method

This study demonstrates a new and realizable possibility of 1T-type ferroelectric random access memory devices using an all solution processing method with cellulose paper substrates. A ferroelectric poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) thin film was formed on a paper substrate with an Al electrode for the bottom-gate structure, and then a semiconducting poly(3-hexylthiophene) (P3HT) thin film was formed on the P(VDF-TrFE)/paper structure using a spin-coating technique. The fabricated ferroelectric gate field-effect transistors (FeFETs) on the cellulose paper substrates demonstrated excellent ferroelectric property with a memory window width of 20 V for a bias voltage sweep from −30 to 30 V, and the on/off ratio of the device was approximately 10². These results agree well with those of the FeFETs fabricated on a rigid Si substrate. In order to compare and check the reproducibility of the characteristics of the FeFETs on the paper substrate, it also has been attempted to make FeFETs with various channel length and width ratios were fabricated. From the measured characteristic results, it can be seen that the electrical properties of FeFETs are almost similar regardless of the substrate type. These results will lead to the emergence of printable electron devices on paper. Furthermore, these nonvolatile paper memory devices, which are fabricated by a solution processing method, are reliable, very inexpensive; have a high density; and can be fabricated easily.