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Excited-State Dynamics in Fully Conjugated 2D Covalent Organic Frameworks.

Accepted version
Peer-reviewed

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Type

Article

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Authors

Jakowetz, Andreas C  ORCID logo  https://orcid.org/0000-0001-7804-7210
Hinrichsen, Ture F 
Ascherl, Laura 
Sick, Torben 
Calik, Mona 

Abstract

Covalent organic frameworks (COFs) are a highly versatile group of porous materials constructed from molecular building blocks, enabling deliberate tuning of their final bulk properties for a broad range of applications. Understanding their excited-state dynamics is essential for identifying suitable COF materials for applications in electronic devices such as transistors, photovoltaic cells, and water-splitting electrodes. Here, we report on the ultrafast excited-state dynamics of a series of fully conjugated two-dimensional (2D) COFs in which different molecular subunits are connected through imine bonds, using transient absorption spectroscopy. Although these COFs feature different topologies and chromophores, we find that excited states behave similarly across the series. We therefore present a unified model in which charges are generated through rapid singlet-singlet annihilation and show lifetimes of several tens of microseconds. These long-lived charges are of particular interest for optoelectronic devices, and our results point toward the importance of controlling the singlet-singlet annihilation step in order to increase the yield of separated charges.

Description

Keywords

0306 Physical Chemistry (incl. Structural), 0303 Macromolecular and Materials Chemistry

Journal Title

J Am Chem Soc

Conference Name

Journal ISSN

0002-7863
1520-5126

Volume Title

141

Publisher

American Chemical Society (ACS)

Rights

All rights reserved
Sponsorship
Engineering and Physical Sciences Research Council (EP/M006360/1)
European Research Council (670405)