Excited-State Dynamics in Fully Conjugated 2D Covalent Organic Frameworks.
Journal of the American Chemical Society
American Chemical Society (ACS)
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Jakowetz, A. C., Hinrichsen, T., Ascherl, L., Sick, T., Calik, M., Auras, F., Medina, D. D., et al. (2019). Excited-State Dynamics in Fully Conjugated 2D Covalent Organic Frameworks.. Journal of the American Chemical Society, 141 (29), 11565-11571. https://doi.org/10.1021/jacs.9b03956
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 watersplitting 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 towards the importance of controlling the singlet-singlet annihilation step in order to increase the yield of separated charges.
ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (670405)
External DOI: https://doi.org/10.1021/jacs.9b03956
This record's URL: https://www.repository.cam.ac.uk/handle/1810/294461
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