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Title: Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks
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.  more » « less
Award ID(s):
1704063
NSF-PAR ID:
10292886
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Chemical Science
Volume:
12
Issue:
24
ISSN:
2041-6520
Page Range / eLocation ID:
8373 to 8384
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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