TY - JOUR A1 - He, Tao A1 - Stolte, Matthias A1 - Burschka, Christian A1 - Hansen, Nis Hauke A1 - Musiol, Thomas A1 - Kälblein, Daniel A1 - Pflaum, Jens A1 - Tao, Xutang A1 - Brill, Jochen A1 - Würthner, Frank T1 - Single-crystal field-effect transistors of new Cl\(_{2}\)-NDI polymorph processed by sublimation in air JF - Nature Communications N2 - Physical properties of active materials built up from small molecules are dictated by their molecular packing in the solid state. Here we demonstrate for the first time the growth of n-channel single-crystal field-effect transistors and organic thin-film transistors by sublimation of 2,6-dichloro-naphthalene diimide in air. Under these conditions, a new polymorph with two-dimensional brick-wall packing mode (\(\beta\)-phase) is obtained that is distinguished from the previously reported herringbone packing motif obtained from solution (\(\alpha\)-phase). We are able to fabricate single-crystal field-effect transistors with electron mobilities in air of up to 8.6 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\alpha\)-phase) and up to 3.5 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\beta\)-phase) on n-octadecyltriethoxysilane-modified substrates. On silicon dioxide, thin-film devices based on \(\beta\)-phase can be manufactured in air giving rise to electron mobilities of 0.37 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\). The simple crystal and thin-film growth procedures by sublimation under ambient conditions avoid elaborate substrate modifications and costly vacuum equipment-based fabrication steps. KW - thin-film transistors KW - carrier transport KW - \(\beta\)-phase KW - organic semiconductors KW - induced phase transition KW - charge transport KW - materials design KW - \(\alpha\)-phase KW - mobility KW - pentacene Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149255 VL - 6 IS - 5954 ER - TY - JOUR A1 - Müller, Ulrich A1 - Spenst, Peter A1 - Kagerer, Philipp A1 - Stolte, Matthias A1 - Würthner, Frank A1 - Pflaum, Jens T1 - Photon‐Correlation Studies on Multichromophore Macrocycles of Perylene Dyes JF - Advanced Optical Materials N2 - Organic dyes offer unique properties for their application as room temperature single photon emitters. By means of photon‐correlation, the emission characteristics of macrocyclic para‐xylylene linked perylene bisimide (PBI) trimers and tetramers dispersed in polymethyl methacrylate matrices are analyzed. The optical data indicate that, despite of the strong emission enhancement of PBI trimers and tetramers according to their larger number of chromophores, the photon‐correlation statistics still obeys that of single photon emitters. Moreover, driving PBI trimers and tetramers at higher excitation powers, saturated emission behavior for monomers is found while macrocycle emission is still far‐off saturation but shows enhanced fluctuations. This observation is attributed to fast singlet–singlet annihilation, i.e., faster than the radiative lifetime of the excited S1 state, and the enlarged number of conformational arrangements of multichromophores in the polymeric host. Finally, embedding trimeric PBI macrocycles in active organic light‐emitting diode matrices, electrically driven bright fluorescence together with an indication for antibunching at room temperature can be detected. This, so far, has only been observed for phosphorescent emitters that feature much longer lifetimes of the excited states and, thus, smaller radiative recombination rates. The results are discussed in the context of possible effects on the g(2) behavior of molecular emitters. KW - multichromophores KW - organic light emitting diodes KW - perylene dyes KW - photon‐correlation KW - single photon emission Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287219 VL - 10 IS - 14 ER - TY - JOUR A1 - Karak, Suvendu A1 - Stepanenko, Vladimir A1 - Addicoat, Matthew A. A1 - Keßler, Philipp A1 - Moser, Simon A1 - Beuerle, Florian A1 - Würthner, Frank T1 - A Covalent Organic Framework for Cooperative Water Oxidation JF - Journal of the American Chemical Society N2 - The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L\(^{–1}\) s\(^{–1}\) (second-order rate constant k ≈ 1650 μmol L s\(^{–1}\) g\(^{–2}\)). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s\(^{–1}\) g\(^{–2}\)) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart. KW - water oxidation KW - sustainable energy source KW - covalent organic framework KW - catalyst KW - crystalline KW - catalysis KW - nanoparticles Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287591 UR - https://pubs.acs.org/doi/10.1021/jacs.2c07282 SN - 0002-7863 VL - 144 IS - 38 ER -