Please use this identifier to cite or link to this item: https://doi.org/10.1021/cm071520x
Title: Conformation-induced electrical bistability in non-conjugated polymers with pendant carbazole moieties
Authors: Lim, S.L.
Ling, Q. 
Teo, E.Y.H. 
Zhu, C.X. 
Chan, D.S.H. 
Kang, E.-T. 
Neoh, K.G. 
Issue Date: 16-Oct-2007
Citation: Lim, S.L., Ling, Q., Teo, E.Y.H., Zhu, C.X., Chan, D.S.H., Kang, E.-T., Neoh, K.G. (2007-10-16). Conformation-induced electrical bistability in non-conjugated polymers with pendant carbazole moieties. Chemistry of Materials 19 (21) : 5148-5157. ScholarBank@NUS Repository. https://doi.org/10.1021/cm071520x
Abstract: Conformation-induced volatile and nonvolatile conductance switching effects were demonstrated in non-conjugated polymers containing the same electroactive pendant groups. Single-layer devices of the structure indium-tin-oxide/polymer/ aluminum were fabricated from two non-conjugated polymers with pendant carbazole groups in different spacer units. The device based on poly(2-(N-carbazolyl) ethyl methacrylate) (PMCz) exhibited nonvolatile write-once-read-many-times (WORM) memory behavior with an ON/OFF current ratio up to 106, while the device based on poly(9-(2-((4-vinylbenzyl)oxy)ethyl)-9H-carbazole) (PVBCz) exhibited volatile memory behavior with an ON/OFF current ratio of approximately 103. The formation of carbazole excimers resulting from conformation-induced conductance switching under an electric field was revealed in situ by fluorescence spectroscopy. The corresponding voltageinduced conformation ordering in the polymer film was captured by transmission electron microscopy. In the absence of a spacer unit between the pendant carbazole group and the main chain, regioregular poly(7Y-vinylcarbazole) (PVK) exhibited only one conductivity state (ON state). The differences in memory behavior among the three polymers were attributed to their inherent differences in the degree of regioregularity and ease of conformational relaxation of the field-induced regioregular carbazole groups. These conformational effects were in turn dictated by the chemical structure and steric effect of the spacer unit between the pendant carbazole group and the main chain. © 2007 American Chemical Society.
Source Title: Chemistry of Materials
URI: http://scholarbank.nus.edu.sg/handle/10635/82081
ISSN: 08974756
DOI: 10.1021/cm071520x
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