Issue 24, 2021

Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks

Abstract

Understanding the underlying physical mechanisms that govern charge transport in two-dimensional (2D) covalent organic frameworks (COFs) will facilitate the development of novel COF-based devices for optoelectronic and thermoelectric applications. In this context, the low-energy mid-infrared absorption contains valuable information about the structure–property relationships and the extent of intra- and inter-framework “hole” polaron delocalization in doped and undoped polymeric materials. In this study, we provide a quantitative characterization of the intricate interplay between electronic defects, domain sizes, pore volumes, chemical dopants, and three dimensional anisotropic charge migration in 2D COFs. We compare our simulations with recent experiments on doped COF films and establish the correlations between polaron coherence, conductivity, and transport signatures. By obtaining the first quantitative agreement with the measured absorption spectra of iodine doped (aza)triangulene-based COF, we highlight the fundamental differences between the underlying microstructure, spectral signatures, and transport physics of polymers and COFs. Our findings provide conclusive evidence of why iodine doped COFs exhibit lower conductivity compared to doped polythiophenes. Finally, we propose new research directions to address existing limitations and improve charge transport in COFs for applications in functional molecular electronic devices.

Graphical abstract: Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks

Supplementary files

Article information

Article type
Edge Article
Submitted
03 Mar 2021
Accepted
12 May 2021
First published
13 May 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 8373-8384

Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks

R. Ghosh and F. Paesani, Chem. Sci., 2021, 12, 8373 DOI: 10.1039/D1SC01262B

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