Solution-Cast Monolayers of Cobalt Crown Ether Phthalocyanine on Highly Ordered Pyrolytic Graphite

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• 作者：Hao Lu ; Iljo Kwak ; Jun Hong Park ; Katie O鈥橬eill ; Taniyuki Furuyama ; Nagao Kobayashi ; Alan Seabaugh ; Andrew Kummel ; Susan K. Fullerton-Shirey
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 24, 2015
• 年：2015
• 卷：119
• 期：38
• 页码：21992-22000
• 全文大小：627K
• ISSN：1932-7455

文摘

15-Crown-5-ether-substituted cobalt(II) phthalocyanine (CoCrPc) is an atomically thin and flat-laying, electrically insulating molecule that can solvate ions; these properties are desirable for nanoelectronic devices. A simple, solution-phase deposition method is demonstrated to produce a monolayer of CoCrPc on highly ordered pyrolytic graphite (HOPG). A uniform and continuous CoCrPc layer is obtained on freshly cleaved HOPG by solution drop casting, followed by thermal annealing under ambient pressure in Ar in the temperature range of 150鈥?10 掳C. While the quality of the monolayer is independent of annealing time, the composition of the annealing atmosphere is critical; exposure to ambient air degrades the quality of the monolayer over the time scale of minutes. Using ultrahigh vacuum scanning tunneling microscopy, a highly ordered and flat CoCrPc layer with hexagonal symmetry and average spacing of 4.09 卤 0.2 nm is observed. The band gap of the CoCrPc, measured by scanning tunneling spectroscopy, is 1.34 卤 0.07 eV. The ability to prepare uniform, ordered, and conformal monolayers of CoCrPc molecules on HOPG represents the first step toward using these materials to seed dielectric growth on 2D crystals and provide a 2D electrolyte for the electrostatic gating of semiconductors at the ultimate limit of scaling.