Mechanically Robust and Highly Flexible Nonvolatile Charge‐Trap Memory Transistors Using Conducting‐Polymer Electrodes and Oxide Semiconductors on Ultrathin Polyimide Film Substrates

Abstract Flexible charge‐trap memory thin‐film transistors (CTM‐TFTs) are fabricated and characterized for next‐generation highly functional consumer electronics. Poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and 1.2‐µm‐thick polyimide (PI) films are introduced as source/drain electrodes and plastic substrates, respectively, to realize highly flexible CTM‐TFTs with conducting polymers. A uniquely structured sacrificial layer is suggested for the lithography‐compatible transfer and patterning processes of PEDOT:PSS on inorganic Al2O3 barrier layers are prepared on the PI substrates. The CTM‐TFTs show significantly improved device performance compared with those of the previous proto‐type devices, including a memory window (MW) of 16.8 V and program speed of 100 µs at a program pulse amplitude of ±20 V. Furthermore, the MWs and on/off current ratio do not shown remarkable degradation, and total variations within a range of less than 7.5% are observed even under harsh bending strains with a curvature radius of 1 mm. Additionally, the mechanical robustness of the fabricated CTM‐TFTs is quantitatively discussed based on the contributions of the conducting polymer electrode and the ultrathin PI film to further improve device performance of the flexible CTM‐TFTs.