Organic memory devices and synaptic simulation based on indacenodithienothiophene (IDTT) copolymers with improved planarity

Utilization of organic semiconductors in memory devices presents the advantages of molecular designability and flexibility. Herein, we present the comparison of three indacenodithieno[3,2-b]thiophene (IDTT) based pi-conjugated polymers via copolymerization with an electron rich thiophene (P1) and two electron deficient co-monomers, thiazole (P2) and 4,4'-dihexadecanoxy-5,5'-bithiazole (P3). The influence of the co-monomer electronic behavior on the thermal, optical and electrochemical properties is exhaustively evaluated. The role that alkoxy substituents of P3 play in possible non-covalent interactions improving the planarity of the polymer backbone is investigated by computational calculations and is confirmed via enhanced thin-film crystallinity and morphological properties. Besides, we construct organic field-effect transistors (OFETs) and three-terminal memory devices based on P1-P3. On account of the well-defined improved planarity, both P3 OFET and P3 flash memory obtain excellent performance with high mobility and a large memory window. The common synapse behaviors, including postsynaptic current under different pulse duration times and pulse voltage as well as repetitive postsynaptic current modulation, are also successfully simulated using our P3 synaptic transistor. This research broadens the application range of IDTT-based pi-conjugated polymers and is an important insight for future information storage techniques and neuromorphic computing using organic electronics.