All-Solution Processed Organic Nonvolatile Memory Thin-Film Transistor Fabricated with Reverse Offset Printing

Abstract

All-solution processed printed organic nonvolatile memory thin film transistors (TFTs) are demonstrated on a large-area substrate. Finely patterned electrodes were fabricated by reverse offset printing with a line width of 15 um and a channel length of 10 um. The memory devices were configured in a bottom-gate bottom-contact TFT structure with a high-k gate blocking insulator poly(vinylidene fluoride-co-trifluoroethylene) (Fig. 1a). A blend ink of a small-molecule p-type organic semiconductor dithieno[2,3-d;2′,3′-d′]benzo[1,2-b;4,5-b′]dithiophene and a tunneling polymer polystyrene were fabricated using air-pulse nozzle printing. The tunneling layer was formed during an active layer printing process with blend ink by phase separation of small-molecule and polymer. The memory devices were manufactured in the same steps as TFT. The printed memory TFTs with the phase-separated tunneling layer exhibited significantly improved on/off ratio (>103 A/A), switching speed (<100 ms) and data retention (>10 years) (Fig. 1b). We believe our finding is applicable to wearable electronics, smart Internet-of-Things devices and neuromorphic computing devices.