Title: Molecular Self-Assembly in a Poorly Screened Environment: F ₄ TCNQ on Graphene/BN

Abstract

We report a scanning tunneling microscopy and noncontact atomic force microscopy study of close-packed 2D islands of tetrafluorotetracyanoquinodimethane (F 4 TCNQ) molecules at the surface of a graphene layer supported by boron nitride. While F 4 TCNQ molecules are known to form cohesive 3D solids, the intermolecular interactions that are attractive for F 4 TCNQ in 3D are repulsive in 2D. Our experimental observation of cohesive molecular behavior for F 4 TCNQ 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.

Authors:

Tsai, Hsin-Zon ^[1]; Omrani, Arash A. ^[1]; Coh, Sinisa ^[2]; Oh, Hyungju ^[2]; Wickenburg, Sebastian ^[2]; Son, Young-Woo ^[3]; Wong, Dillon ^[1]; Riss, Alexander ^[1]; Jung, Han Sae ^[1]; Nguyen, Giang D. ^[1]; Rodgers, Griffin F. ^[1]; Aikawa, Andrew S. ^[1]; Taniguchi, Takashi ^[4]; Watanabe, Kenji ^[4]; Zettl, Alex ^[5]; Louie, Steven G. ^[2]; Lu, Jiong ^[6]; Cohen, Marvin L. ^[2]; Crommie, Michael F. ^[5]

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+ Show Author Affiliations

1. Department of Physics, University of California, Berkeley, California 94720, United States
2. Department of Physics, University of California, Berkeley, California 94720, United States, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Department of Physics, University of California, Berkeley, California 94720, United States, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States, Korea Institute for Advanced Study, Seoul 130-722, Korea
4. National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
5. Department of Physics, University of California, Berkeley, California 94720, United States, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States, Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
6. Department of Physics, University of California, Berkeley, California 94720, United States, Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore, Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore

Publication Date:

Wed Oct 28 00:00:00 EDT 2015

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1224916

Alternate Identifier(s):

OSTI ID: 1257350; OSTI ID: 1378599

Grant/Contract Number:  

AC02-05CH11231; J3026-N16; R-144-000-295-281; P2ELP2-151852; 32 CFR 168a; DMR-1206512

Resource Type:

Published Article

Journal Name:

ACS Nano

Additional Journal Information:

Journal Name: ACS Nano Journal Volume: 9 Journal Issue: 12; Journal ID: ISSN 1936-0851

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION; molecular self-assembly; graphene; hexagonal boron nitride (BN); scanning tunneling microscopy (STM); noncontact atomic force microscopy (nc-AFM); density functional theory (DFT); 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE