Local Electronic Structure of Molecular Heterojunctions in a Single‐Layer 2D Covalent Organic Framework
Abstract
The synthesis of a single‐layer covalent organic framework (COF) with spatially modulated internal potentials provides new opportunities for manipulating the electronic structure of molecularly defined materials. Here, the fabrication and electronic characterization of COF‐420: a single‐layer porphyrin‐based square‐lattice COF containing a periodic array of oriented, type II electronic heterojunctions is reported. In contrast to previous donor–acceptor COFs, COF‐420 is constructed from building blocks that yield identical cores upon reticulation, but that are bridged by electrically asymmetric linkers supporting oriented electronic dipoles. Scanning tunneling spectroscopy reveals staggered gap (type II) band alignment between adjacent molecular cores in COF‐420, in agreement with first‐principles calculations. Hirshfeld charge analysis indicates that dipole fields from oriented imine linkages within COF‐420 are the main cause of the staggered electronic structure in this square grid of atomically–precise heterojunctions.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 28, 2018
- Source ID
- 10.1002/adma.201805941
Entities
People
- Chen Chen
- Christian S Diercks
- Gaoqiang Wang
- Hong Li
- Huifang Li
- Jean‐luc Brédas
- Michael F. Crommie
- Omar M. Yaghi
- Peter J Waller
- Trinity Joshi
Organizations
- Army Research Office
- Georgia Tech
- King Abdullah University of Science and Technology
- Lawrence Berkeley National Laboratory
- National Science Foundation
- United States Department of Energy
- University of California, Berkeley
- University of Chinese Academy of Sciences