Synthesis and non-volatile electrical memory characteristics of triphenylamine-based polyimides with flexibility segments

• Published in: New journal of chemistry 2018, Vol.42 (23), p.19008-19019
• Main Authors: Yang, Yanhua, Xia, Jing-Cheng, Zheng, Youxuan, Shen, Yingzhong, Gou, Gaozhang
• Format: Article
• Language: English
• Subjects: Charge transfer; Chemical synthesis; Dipole moments; Electric fields; Flash memory (computers); Flexibility; Memory devices; NMR; Nuclear magnetic resonance; Polyimide resins; Random access memory; Thermal stability; Threshold voltage
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C8NJ04103B

An efficient and readily available novel asymmetric diamine monomer containing a strongly electron-donating triphenylamine moiety and a flexibility segment was designed and synthesized through a Suzuki coupling reaction. Then, two thermally stable and highly soluble polyimides ( PI(TPA-PMDA) and PI(TPA-BPDA) ) were prepared and characterized. The ITO/ PI(TPA-PMDA) /Al memory device exhibited write-once read-many-times (WORM) memory behavior with a threshold voltage of −1.12 V, while the PI(TPA-BPDA) memory device demonstrated flash-type memory behavior with a turn-on voltage at −0.78 V and a turn-off voltage at +1.98 V. Both devices showed high ON/OFF current ratios beyond 10 3 and long retention times of 4 × 10 3 s. Space-charge limited-current (SCLC) conduction and local filament conduction governed the OFF- and ON-state current conduction of the two memory devices, respectively. The electrical memory switching behaviors were induced by a charge transfer process under an applied electric field, and the differences between the dihedral angles and dipole moments resulted in different memory types.