Preparation of homopolymers from new azobenzene organic molecules with different terminal groups and study of their nonvolatile memory effects

Two new azo organic molecules Azo-OCH3 and Azo-Br were synthesized by using electron-donating moiety methoxyphenyl and electron-accepting moiety bromophenyl as a terminal group respectively. Two monomers MAzo-OCH3 and MAzo-Br based on them were also synthesized and corresponding homopolymers PAzo-OCH3 and PAzo-Br were prepared by free radical polymerization. Azo-OCH3 and Azo-Br were fabricated as films by vacuum evaporation while PAzo-OCH3 and PAzo-Br were fabricated as films by simple spin-coating and all of them were then prepared as sandwich memory devices ITO/Azo-OCH3/Al, ITO/Azo-Br/Al, ITO/PAzo-OCH3/Al and ITO/PAzo-Br/Al respectively. According to the measurements, all devices exhibited stable binary WORM-type (write once and read many times) memory effects. However, ITO/Azo-OCH3/Al and ITO/Azo-Br/Al exhibited different turn-on threshold voltages of about −2, −3.6 V respectively. It illustrated that to organic molecule anchoring electron-donor as a terminal group shows lower turn-on threshold voltage, which was related to low-power consumption. Moreover, the ITO/polymer/Al devices have successfully preserved the memory performance of devices based on corresponding organic molecules. Therefore, we successfully achieved the advantages of low-cost and low-power consumption by designing molecular structures and easy fabrication by polymerization.

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