Electrical memory characteristics of a nondoped π-conjugated polymer bearing carbazole moieties

Samdae Park, Taek Joon Lee, Dong Min Kim, Jin Chul Kim, Kyungtae Kim, Wonsang Kwon, Yong Gi Ko, Heungyeal Choi, Taihyun Chang, Moonhor Ree

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Poly[bis(9H-carbazole-9-ethyl)dipropargylmalonate] (PCzDPM) is a novel π-conjugated polymer bearing carbazole moieties that has been synthesized by polymerization of bis(9H-carbazole-9-ethyl)dipropargylmalonate with the aid of molybdenum chloride solution as the catalyst. This polymer is thermally stable up to 255 °C under a nitrogen atmosphere and 230 °C in air ambient; its glass-transition temperature is 147 or 128 °C, depending on the polymer chain conformation (helical or planar structure). The charge-transport characteristics of PCzDPM in nanometer-scaled thin films were studied as a function of temperature and film thickness. PCzDPM films with a thickness of 15-30 nm were found to exhibit very stable dynamic random access memory (DRAM) characteristics without polarity. Furthermore, the polymer films retain DRAM characteristics up to 180 °C. The ON-state current is dominated by Ohmic conduction, and the OFF-state current appears to undergo a transition from Ohmic to space-charge-limited conduction with a shallow-trap distribution. The ON/OFF switching of the devices is mainly governed by filament formation. The filament formation mechanism for the switching process is supported by the metallic properties of the PCzDPM film, which result in the temperature dependence of the ON-state current. In addition, the structure of this π-conjugated polymer was found to vary with its thermal history; this change in structure can affect filament formation in the polymer film.

Original languageEnglish (US)
Pages (from-to)10294-10301
Number of pages8
JournalJournal of Physical Chemistry B
Volume114
Issue number32
DOIs
StatePublished - Aug 19 2010
Externally publishedYes

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