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End date: 2024 × Start date: 2020 × DDC: 540 × Subject: Functionalizations ×

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    Scalable Functionalization of Optical Fibers Using Atomically Thin Semiconductors
    (Weinheim : Wiley-VCH Verlag, 2020) Ngo G.Q.; George A.; Schock R.T.K.; Tuniz A.; Najafidehaghani E.; Gan Z.; Geib N.C.; Bucher T.; Knopf H.; Saravi S.; Neumann C.; Lühder T.; Schartner E.P.; Warren-Smith S.C.; Ebendorff-Heidepriem H.; Pertsch T.; Schmidt M.A.; Turchanin A.; Eilenberger F.
    Atomically thin transition metal dichalcogenides are highly promising for integrated optoelectronic and photonic systems due to their exciton-driven linear and nonlinear interactions with light. Integrating them into optical fibers yields novel opportunities in optical communication, remote sensing, and all-fiber optoelectronics. However, the scalable and reproducible deposition of high-quality monolayers on optical fibers is a challenge. Here, the chemical vapor deposition of monolayer MoS2 and WS2 crystals on the core of microstructured exposed-core optical fibers and their interaction with the fibers’ guided modes are reported. Two distinct application possibilities of 2D-functionalized waveguides to exemplify their potential are demonstrated. First, the excitonic 2D material photoluminescence is simultaneously excited and collected with the fiber modes, opening a novel route to remote sensing. Then it is shown that third-harmonic generation is modified by the highly localized nonlinear polarization of the monolayers, yielding a new avenue to tailor nonlinear optical processes in fibers. It is anticipated that the results may lead to significant advances in optical-fiber-based technologies. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Mixed-halide triphenyl methyl radicals for site-selective functionalization and polymerization
    (London : RSC Publishing, 2021) Chen, Lisa; Arnold, Mona; Blinder, Rémi; Jelezko, Fedor; Kuehne, Alexander J. C.
    Derivatives of the stable, luminescent tris-2,4,6-trichlorophenylmethyl (TTM) radical exhibit unique doublet spin properties that are of interest for applications in optoelectronics, spintronics, and energy storage. However, poor reactivity of the chloride-moieties limits the yield of functionalization and thus the accessible variety of high performance luminescent radicals. Here, we present a pathway to obtain mixed-bromide and chloride derivatives of TTM by simple Friedel–Crafts alkylation. The resulting radical compounds show higher stability and site-specific reactivity in cross-coupling reactions, due to the better leaving group character of the para-bromide. The mixed halide radicals give access to complex, and so far inaccessible luminescent open-shell small molecules, as well as polymers carrying the radical centers in their backbone. The new mixed-halide triphenyl methyl radicals represent a powerful building block for customized design and synthesis of stable luminescent radicals.