Highly Reliable Top-Gated Thin-Film Transistor Memory with Semiconducting, Tunneling, Charge-Trapping, and Blocking Layers All of Flexible Polymers

The core components of a floating-gate organic thin-film transistor nonvolatile memory (OTFT-NVM) include the semiconducting channel layer, tunneling layer, floating-gate layer, and blocking layer, besides three terminal electrodes. In this study, we demonstrated OTFT-NVMs with all four constituent layers made of polymers based on consecutive spin-coating. Ambipolar charges injected and trapped in a polymer electret charge-controlling layer upon gate program and erase field successfully allowed for reliable bistable channel current levels at zero gate voltage. We have observed that the memory performance, in particular the reliability of a device, significantly depends upon the thickness of both blocking and tunneling layers, and with an optimized layer thickness and materials selection, our device exhibits a memory window of 15.4 V, on/off current ratio of 2 × 10⁴, read and write endurance cycles over 100, and time-dependent data retention of 10⁸ s, even when fabricated on a mechanically flexible plastic substrate. (Chemical Equation Presented).