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Title: Conductivity switching and electronic memory effect in polymers with pendant azobenzene chromophores
Authors: Lim, S.L.
Li, N.-J.
Lu, J.-M.
Ling, Q.-D. 
Zhu, C.X.
Kang, E.-T. 
Neoh, K.G. 
Keywords: azobenzene
charge trapping
conductance switching
electron acceptor
electron donor
polymer memory
Issue Date: 28-Jan-2009
Citation: Lim, S.L., Li, N.-J., Lu, J.-M., Ling, Q.-D., Zhu, C.X., Kang, E.-T., Neoh, K.G. (2009-01-28). Conductivity switching and electronic memory effect in polymers with pendant azobenzene chromophores. ACS Applied Materials and Interfaces 1 (1) : 60-71. ScholarBank@NUS Repository.
Abstract: Electronic memory devices having the indium-tin oxide/polymer/Al sandwich structure were fabricated from polymers containing pendant azobenzene chromophores in donor-acceptor structures. The reversibility, or rewritability, of the high-conductivity (ON) state was found to be dependant on the terminal moiety of the azobenzene chromophore. While the polymers with electron-accepting terminal moieties (-Br or -NO2) in the pendant azobenzene exhibit write-once, read-many-times (WORM) type memory behavior, those with electron-donating terminal moieties (-OCH3) exihibit rewritable (FLASH) memory behavior. The WORM memory devices have low switching ("write") voltages below -2 V and high ON/OFF current ratios of about 104-106. The polarity of the "write" voltage can be reversed by using an electrode with a higher work function than Al, thus excluding metallic filamentary conduction as a cause of the bistable switching phenomenon. The FLASH memory devices have low "write" and "erase" voltages of about -1.7 to -1.8 V and 2.0 to 2.2 V, respectively, and ON/OFF current ratios of about 103-104. The electrical bistability observed can be attributed to charge trapping at the azobenzene chromophores, resulting in the charge-separated, high-conductivity state. The proposed mechanism is supported experimentally by a red shift and peak broadening in the UV-visible absorption spectra of the polymer films resulting from the OFF-to-ON electrical transition. © 2008 American Chemical Society.
Source Title: ACS Applied Materials and Interfaces
ISSN: 19448244
DOI: 10.1021/am800001e
Appears in Collections:Staff Publications

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