Control over memory performance of layer-by-layer assembled metal phthalocyanine multilayers via molecular-level manipulation

Bonkee Koo, Hyunhee Baek, Jinhan Cho

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We herein report on the nonvolatile memory properties of iron phthalocyanine multilayers prepared using an electrostatic layer-by-layer assembly method. Cationic poly(allylamine hydrochloride) (PAH) and anionic iron(III) phthalocyanine-4, 4,′ 4″, 4‴-tetrasulfonic acid (Fe-TsPc) were alternately deposited onto quartz glass, indium tin oxide (ITO), or platinum-coated silicon substrates via electrostatic interactions. The electrochemical response of the PAH/Fe-TsPc, which was obtained from cyclic voltammograms (CV) in solution, indicated that redox reactions occurred at the phthalocyanine unit and at the metallic center. It was found that these redox reactions of the PAH/Fe-TsPc multilayer films in solution could be extended to resistive switching nonvolatile memory based on a charge trap/release mechanism in air. The PAH/Fe-TsPc multilayers sandwiched between the bottom (platinum) and top (Ag or tungsten) electrodes exhibited the characteristics of a resistive switching memory at a relatively low operating voltage of less than 2 V, with a switching speed of about 100 ns and an ON/OFF current ratio of ∼10 3. Additionally, it is confirmed using kelvin probe force microscopy (KPFM) that the reversible resistance changes in the PAH/Fe-TsPc multilayers are mainly caused by the externally applied voltage as a result of the trapping and release of charges at redox sites within the Fe-TsPc. Furthermore, in the case where insulating layers of about 2 nm in thickness are inserted between adjacent Fe-TsPc layers, it is demonstrated that these devices can exhibit further improvements in memory performance (ON/OFF current ratio of ∼10 6) and a lower power consumption in comparison with PAH/Fe-TsPc multilayers.

Original languageEnglish
Pages (from-to)1091-1099
Number of pages9
JournalChemistry of Materials
Volume24
Issue number6
DOIs
Publication statusPublished - 2012 Mar 27

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Control over memory performance of layer-by-layer assembled metal phthalocyanine multilayers via molecular-level manipulation'. Together they form a unique fingerprint.

  • Cite this