Binary/ternary memory behavior of organo-solubility polyimides containing flexible imide linkages and pendent triphenylamine or 3, 4, 5-trifluobenzene moieties. (15th February 2020) - Ye, Qingqing
Graphical abstract: Two novel aromatic diamines containing flexible imide linkages were synthesized via a Suzuki coupling reaction. Then the four corresponding functional polyimides (PI-a, PI-b, PI-c, and PI-d) were prepared. The devices of PI-a and PI-b displayed non-volatile binary WORM and Flash behaviors with turn-on voltages of −1.13 V and −1.54 V, respectively. However, the PI-c-based and PI-d-based devices showed non-volatile ternary WORM and Flash behaviors with turn-on voltages of −0.77 V, as well as −1.77 V, respectively. Highlights: Two novel aromatic diamine containing flexible imide linkages moiety and different substituent moieties were synthesized via Suzuki coupling reaction. Four functional polyimides were prepared by chemical imidization. The memory devices based on these polyimides exhibited binary and ternary memory behaviors, respectively. Abstract: Two different aromatic diamines monomers (3, 5-diamino-N-(4'-phenyl-4''-triphenylamino)-N-(4''-benzyl-4'''-triphenylamino)benzamide (DPTBTB) and 3, 5-diamino-N-(4'-3'', 4'', 5''-trifluorobiphenyl)-N-(4''-benzyl-3''', 4''', 5'''-trifluorophenyl)benzamide (DTBTB)) containing flexible linkages were designed and synthesized, respectively. Four organo-solubility polyimides (PI-a, PI-b, PI-c, and PI-d) were prepared via a two-step procedure with pyromellitic dianhydride (PMDA) and 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA), respectively. The four PIs performed excellent thermal stability with the temperature of 5% weight loss in range of 370–420 ℃ at N2 atmosphere. The Al/PI-a/ITO and Al/PI-b/ITO memory devices exhibited binary write-once-many-read (WORM) and rewritable (Flash) behavior, respectively. But the Al/PI-c/ITO and Al/PI-d/ITO memory devices showed ternary WORM and Flash behavior due to the deeper charge traps came from the fluorinated groups in the structure of PI-c and PI-d, respectively. The memory switching mechanism could be demonstrated through molecular simulation. The results gave an effective strategy that adjusting the structure of PI to achieve different memory effects.