Synthesis And Electronic Memory Characteristics Of Azo Compounds

Azo group is an active groups of excellent electrical properties. Small organicmolecules containing the azo moieties have been widely used in the researches anddevelopments of various types of electric memory materials. The as-fabricated devices hadthe high ON/OFF current ratio, and the low turn-on voltage. And the electric storageperformance is exceedingly stable. The research group prepared the optical responsedevices with using the structure changes of cis-trans zao groups under the opticalexcitation conditions. It was synthesized that is a series of azo molecules includingsulfonyl moieties in this paper. And polymers were synthesized in which the side chain wasconjugated. The memory devices were fabricated from these small molecules and polymers,which had the sandwich structure such as ITO/Organic (polymer)/Al. And then thememory effects were studied.The research items are as follows:(1) A series of azo molecules (Azo1and Azo2) including sulfonyl moieties weresynthesized and characterized. The memory devices possess a sandwich structurecomprising bottom indium-tin oxide (ITO) electrode and top Al electrode. The memorycharacteristics of were tested by the semiconductor parameter analyzer. The as-fabricateddevices were found to have the characteristic of ternary data-storage, and could be from alow-conductivity (“0”) state programmed irreversibly to an intermediate-conductivity (“1”)state and then to a high-conductivity (“2”) state. The retention ability of the Off, middleand On states of the device was investigated under a constant voltage stress of-0.7V. Thememory capacity of the device increases from2nto3n, compared to the bistable materials’.(2) An asymmetric small molecule (Azo5) was designed and synthesized which wascontaining a sulfonyl moiety and two different azo groups. The current increased suddenly three times when the device was added into the external electric field. And the device couldmaintain10hours in the current conductive state with the continuous scanning voltage-1.0V. So the device could realize the quaternary electric memory. The electric memoryproperties of Azo5were studied by comparing with a series of molecules (Azo3and Azo4),in order to explore the theory of charge trapping.(3) A polymethacrylate containing pendant2-methylbenzothiazole (pBVMA) withgood thermal stability was synthesized by free radical polymerization. The devices basedon pBVMA possess a sandwich structure comprising bottom indium-tin oxide (ITO)electrode and top Al electrode. The as-fabricated device exhibits the dynamic randomaccess memory (DRAM) behavior with an ON/OFF current ratio up to105and can endure108read cycles under-1V pulse voltage. The effect of the film thickness on the deviceperformance was investigated and the devices fabricated with75nm and45nm thickpBVMA films were both found to exhibit DRAM type memory behaviors, which mayindicate that the Al nanoparticles had no penetration into the thin film during thevacuum-deposition process. The molecular simulation and physical theoretical modelswere analyzed and the mechanism of the DRAM performance may be attributed to theweak electron withdrawing ability of the molecule.