Revealing the Local Electronic Structure of a Single-Layer Covalent Organic Framework through Electronic Decoupling

作者：Daniel J. Rizzo, Qingqing Dai, Christopher Bronner, Gregory Veber, Brian J. Smith, Michio Matsumoto, Simil Thomas, Giang D. Nguyen, Patrick Forrester, William Zhao, Jakob Holm Jørgensen, William R. Dichtel, Felix R. Fischer, Hong Li, Jean‐Luc Brédas, Michael F. Crommie · 发表于：Nano Letters · 年份：2020 · DOI：10.1021/acs.nanolett.9b03998 · 被引用次数：48 · 研究领域：Covalent Organic Framework Applications、Surface Chemistry and Catalysis、Graphene research and applications

Covalent organic frameworks (COFs) are molecule-based 2D and 3D materials that possess a wide range of mechanical and electronic properties. We have performed a joint experimental and theoretical study of the electronic structure of boroxine-linked COFs grown under ultrahigh vacuum conditions and characterized using scanning tunneling spectroscopy on Au(111) and hBN/Cu(111) substrates. Our results show that a single hBN layer electronically decouples the COF from the metallic substrate, thus suppressing substrate-induced broadening and revealing new features in the COF electronic local density of states (LDOS). The resulting sharpening of LDOS features allows us to experimentally determine the COF band gap, bandwidths, and the electronic hopping amplitude between adjacent COF bridge sites. These experimental parameters are consistent with the results of first-principles theoretical predictions.