Molecular Self-Assembly in a Poorly Screened Environment: F4TCNQ on Graphene/BN

详细信息    查看全文

• 作者：Hsin-Zon Tsai ; Arash A. Omrani ; Sinisa Coh ; Hyungju Oh ; Sebastian Wickenburg ; Young-Woo Son ; Dillon Wong ; Alexander Riss ; Han Sae Jung ; Giang D. Nguyen ; Griffin F. Rodgers ; Andrew S. Aikawa ; Takashi Taniguchi ; Kenji Watanabe ; Alex Zettl ; Steven G. Louie ; Jiong Lu ; Marvin L. Cohen ; Michael F. Crommie
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：December 22, 2015
• 年：2015
• 卷：9
• 期：12
• 页码：12168-12173
• 全文大小：367K
• ISSN：1936-086X

文摘

We report a scanning tunneling microscopy and noncontact atomic force microscopy study of close-packed 2D islands of tetrafluorotetracyanoquinodimethane (F₄TCNQ) molecules at the surface of a graphene layer supported by boron nitride. While F₄TCNQ molecules are known to form cohesive 3D solids, the intermolecular interactions that are attractive for F₄TCNQ in 3D are repulsive in 2D. Our experimental observation of cohesive molecular behavior for F₄TCNQ on graphene is thus unexpected. This self-assembly behavior can be explained by a novel solid formation mechanism that occurs when charged molecules are placed in a poorly screened environment. As negatively charged molecules coalesce, the local work function increases, causing electrons to flow into the coalescing molecular island and increase its cohesive binding energy.