溶液プロセスを用いたトップゲート有機トランジスタと不揮発性メモリ応用

抄録

The use of a top-gate/bottom-contact (TG/BC) configuration in organic thin-film transistors (OTFTs) is an effective strategy for achieving high electrical performance and facilitating device integration in organic electronic circuits. We found that TG/BC OTFTs incorporating spin-coated poly (3-hexylthiophene) (P3HT) films exhibited high field-effect mobilities, regardless of the substrate surface energy or the dielectric constant of the gate insulators. These results strongly suggest the formation of a highly ordered, edge-on-oriented structure at the surface of the P3HT films, which serves as the carrier transport region in TG/BC OTFTs. Solution-processed TG/BC OTFTs also demonstrated excellent electrical stability under gate bias stress, outperforming both bottom-gate OTFTs and inorganic TFTs. We further developed solution-processable nonvolatile memory devices by integrating polymer-based TG/BC OTFTs with the vertical phase separation observed in solution-processed organic blend films composed of a polymer insulator, such as polystyrene or poly(methyl methacrylate), and a soluble small-molecule semiconductor, TIPS-pentacene. The resulting solution-processed TG/BC P3HT OTFT memory exhibited a large threshold voltage shift of over 30 V when programmed under light illumination, due to the storage of photogenerated electrons in the organic floating-gate layer. Moreover, diketopyrrolopyrrole-based ambipolar polymer semiconductors enabled electrically programmable and erasable memory operation. By tuning the work functions of the gate electrodes, NAND-type memory operations were successfully demonstrated in OTFT memory devices connected in series.