Isoindigo-Based Donor-Acceptor Conjugated Polymers for Air-Stable Nonvolatile Memory Devices

Nonvolatile resistive memory devices based on a new low bandgap donor-acceptor (D-A) conjugated polymer, poly((E)-6,6'-bis(2,3-dihydrothieno[3,4-b][1,4]dioxine-5-yl)-1,1'-bis(2-octyldodecyl)-[3,3'-biindolinyi-dene]-2,2'-dione) (PIDED), which are fabricated and operated in ambient air, are reported. The D-A conjugated polymer is synthesized from 2,3-dihydrothieno[3,4-b][1,4]dioxine and isoindigo as an electron donor and an electron acceptor, respectively, using CH-arylation polymerization. The devices show nonvolatile, unipolar resistive switching behaviors with a high on/off current ratio (∼10⁴), excellent endurance cycles (>200 cycles), and a long retention time (>10⁴ s) in ambient air. These properties remain stable in ambient air over one year, demonstrating that the device performance is significantly unaffected by exposure to air as the isoindigo has strong electron-withdrawing character and the PIDED exhibits a high degree of crystallinity. This study may pave the way for use of practical nonvolatile organic memory devices operating in ambient air.