TY - JOUR AB - The alignment of liquid crystals on surfaces plays a central role in optimizing their performances. In this work, a cutting-edge nano-lithography-based method to control the local orientation of a thermotropic liquid crystal is applied to easily available commercial standard materials and evaluated. Parallel nanogrooves on a substrate, created through 3D nanoprinting in a negative-tone photoresin optimized for two-photon polymerization are used for this purpose. Azimuthal anchoring energies of the order from 10−6 J/m2 to 10−5 J/m2 are found, depending on the spacing, width and depth of the grooves. In part, these values are larger than those reported previously for another photopolymer. Both uniform alignment and spatial patterns of different alignment directions can be realized. Electro-optic studies confirm the suitability of the method for electrically addressable photonic applications and indicate strong polar anchoring. AU - Zhang, Bingru AU - Plidschun, Malte AU - Schmidt, Markus A. AU - Kitzerow, Heinz-Siegfried ID - 49609 IS - 12 JF - Optical Materials Express KW - Electronic KW - Optical and Magnetic Materials SN - 2159-3930 TI - Anchoring and electro-optic switching of liquid crystals on nano-structured surfaces fabricated by two-photon based nano-printing VL - 13 ER - TY - JOUR AB - Geometric-phase dielectric meta-lenses made of silicon with high numerical aperture and short focal lengths are fabricated and characterised. For circularly polarised light, the same meta-lens can act as a converging or diverging lens, depending on the handedness of the circular polarisation. This effect enables application for optical tweezers that trap or release µm-size polymer beads floating in a microfluidic channel on demand. An electrically addressable polarisation converter based on liquid crystals may be used to switch between the two states of polarisation, at which the light transmitted through the meta-lens is focused (trapping) or defocussed (releasing), respectively. AU - Geromel, René AU - Rennerich, Roman AU - Zentgraf, Thomas AU - Kitzerow, Heinz-Siegfried ID - 40513 IS - 7-10 JF - Liquid Crystals TI - Geometric-phase metalens to be used for tunable optical tweezers in microfluidics VL - 50 ER - TY - JOUR AU - Zhang, Bingru AU - Nguyen, Linh AU - Martens, Kevin AU - Heuer-Jungemann, Amelie AU - Philipp, Julian AU - Kempter, Susanne AU - Rädler, Joachim O. AU - Liedl, Tim AU - Kitzerow, Heinz-Siegfried ID - 43440 IS - 7-10 JF - Liquid Crystals KW - Condensed Matter Physics KW - General Materials Science KW - General Chemistry SN - 0267-8292 TI - Luminescent DNA-origami nano-rods dispersed in a lyotropic chromonic liquid crystal VL - 50 ER - TY - JOUR AB - AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands. AU - Wiebeler, Christian AU - Vollbrecht, Joachim AU - Neuba, Adam AU - Kitzerow, Heinz-Siegfried AU - Schumacher, Stefan ID - 39653 IS - 1 JF - Scientific Reports KW - Multidisciplinary SN - 2045-2322 TI - Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters VL - 11 ER - TY - JOUR AU - Atorf, Bernhard AU - Mühlenbernd, Holger AU - Zentgraf, Thomas AU - Kitzerow, Heinz-Siegfried ID - 16301 IS - 6 JF - Optics Express SN - 1094-4087 TI - All-optical switching of a dye-doped liquid crystal plasmonic metasurface VL - 28 ER - TY - JOUR AU - Keum, Changmin AU - Becker, David AU - Archer, Emily AU - Bock, Harald AU - Kitzerow, Heinz-Siegfried AU - Gather, Malte C. AU - Murawski, Caroline ID - 35869 IS - 17 JF - Advanced Optical Materials KW - Atomic and Molecular Physics KW - and Optics KW - Electronic KW - Optical and Magnetic Materials SN - 2195-1071 TI - Organic Light‐Emitting Diodes Based on a Columnar Liquid‐Crystalline Perylene Emitter VL - 8 ER - TY - JOUR AU - Risse, Anna Margareta AU - Schmidtke, Jürgen AU - Kitzerow, Heinz-Siegfried ID - 35859 IS - 7 JF - Liquid Crystals KW - Condensed Matter Physics KW - General Materials Science KW - General Chemistry SN - 0267-8292 TI - Dynamics of a liquid crystal-based modulator with germanium substrates for mid-infrared radiation VL - 48 ER - TY - JOUR AB - Rod-like and sheet-like nano-particles made of desoxyribonucleic acid (DNA) fabricated by the DNA origami method (base sequence-controlled self-organized folding of DNA) are dispersed in a lyotropic chromonic liquid crystal made of an aqueous solution of disodium cromoglycate. The respective liquid crystalline nanodispersions are doped with a dichroic fluorescent dye and their orientational order parameter is studied by means of polarized fluorescence spectroscopy. The presence of the nano-particles is found to slightly reduce the orientational order parameter of the nematic mesophase. Nano-rods with a large length/width ratio tend to preserve the orientational order, while more compact stiff nano-rods and especially nano-sheets reduce the order parameter to a larger extent. In spite of the difference between the sizes of the DNA nano-particles and the rod-like columnar aggregates forming the liquid crystal, a similarity between the shapes of the former and the latter seems to be better compatible with the orientational order of the liquid crystal. AU - Zhang, Bingru AU - Martens, Kevin AU - Kneer, Luisa AU - Funck, Timon AU - Nguyen, Linh AU - Berger, Ricarda AU - Dass, Mihir AU - Kempter, Susanne AU - Schmidtke, Jürgen AU - Liedl, Tim AU - Kitzerow, Heinz-Siegfried ID - 35868 IS - 9 JF - Nanomaterials KW - General Materials Science KW - General Chemical Engineering SN - 2079-4991 TI - DNA Origami Nano-Sheets and Nano-Rods Alter the Orientational Order in a Lyotropic Chromonic Liquid Crystal VL - 10 ER - TY - JOUR AU - Atorf, Bernhard AU - Auf der Landwehr, Chris Holm AU - Rennerich, Roman AU - Kitzerow, Heinz-Siegfried ID - 13870 JF - The Journal of Physical Chemistry B SN - 1520-6106 TI - Midinfrared Birefringence of Liquid Crystals, Polarimetry, and Intensity Modulators ER - TY - JOUR AU - Zhang, Bingru AU - Schmidtke, Jürgen AU - Kitzerow, Heinz-Siegfried ID - 35872 IS - 8 JF - Advanced Optical Materials KW - Atomic and Molecular Physics KW - and Optics KW - Electronic KW - Optical and Magnetic Materials SN - 2195-1071 TI - Fabrication of Lyotropic Alignment Layers for Thermotropic Liquid Crystals Facilitated by a Polymer Template VL - 7 ER - TY - CONF AU - Temme, Julian AU - Meyers, Thorsten AU - Reker, Julia AU - Vidor, Fábio F. AU - Vollbrecht, Joachim AU - Kitzerow, Heinz-Siegfried AU - Paradies, Jan AU - Hilleringmann, Ulrich ED - du Plessis, Monuko ID - 35870 T2 - Fifth Conference on Sensors, MEMS, and Electro-Optic Systems TI - Improved organic thin-film transistor performance by dielectric layer patterning ER - TY - JOUR AU - Kitzerow, Heinz-Siegfried ID - 39971 IS - 1 JF - Liquid Crystals Today KW - Materials Chemistry KW - Inorganic Chemistry KW - Condensed Matter Physics SN - 1358-314X TI - Pawel Pieranski – crystallographer of liquids and Alfred-Saupe-prize laureate 2019 VL - 28 ER - TY - JOUR AU - Vollbrecht, Joachim AU - Wiebeler, Christian AU - Bock, Harald AU - Schumacher, Stefan AU - Kitzerow, Heinz-Siegfried ID - 13343 IS - 7 JF - The Journal of Physical Chemistry C SN - 1932-7447 TI - Curved Polar Dibenzocoronene Esters and Imides versus Their Planar Centrosymmetric Homologs: Photophysical and Optoelectronic Analysis VL - 123 ER - TY - JOUR AU - Atorf, Bernhard AU - Friesen, Simon AU - Rennerich, Roman AU - Mühlenbernd, Holger AU - Zentgraf, Thomas AU - Kitzerow, Heinz-Siegfried ID - 8798 JF - Polymer Science, Series C SN - 1811-2382 TI - Switchable Plasmonic Metasurface Utilizing the Electro-Optic Kerr Effect of a Blue Phase Liquid Crystal VL - 60 ER - TY - JOUR AU - Atorf, Bernhard AU - Rasouli, Hoda AU - Mühlenbernd, Holger AU - Reineke, Bernhard J. AU - Zentgraf, Thomas AU - Kitzerow, Heinz-Siegfried ID - 1764 IS - 8 JF - The Journal of Physical Chemistry C SN - 1932-7447 TI - Switchable Plasmonic Holograms Utilizing the Electro-Optic Effect of a Liquid-Crystal Circular Polarizer VL - 122 ER - TY - JOUR AU - Atorf, Bernhard AU - Friesen, Simon AU - Rennerich, Roman AU - Mühlenbernd, Holger AU - Zentgraf, Thomas AU - Kitzerow, Heinz-Siegfried ID - 13871 JF - Polymer Science, Series C SN - 1811-2382 TI - Switchable Plasmonic Metasurface Utilizing the Electro-Optic Kerr Effect of a Blue Phase Liquid Crystal ER - TY - JOUR AU - Vollbrecht, Joachim AU - Oechsle, Peter AU - Stepen, Arne AU - Hoffmann, Florian AU - Paradies, Jan AU - Meyers, Thorsten AU - Hilleringmann, Ulrich AU - Schmidtke, Jürgen AU - Kitzerow, Heinz-Siegfried ID - 22244 JF - Organic Electronics SN - 1566-1199 TI - Liquid crystalline dithienothiophene derivatives for organic electronics ER - TY - JOUR AU - Vollbrecht, Joachim AU - Stepen, Arne AU - Nolkemper, Karlo AU - Keuker-Baumann, Susanne AU - Kitzerow, Heinz-Siegfried ID - 39659 IS - 1 JF - Polymer Science, Series C KW - Materials Chemistry KW - Polymers and Plastics KW - General Chemistry SN - 1811-2382 TI - Blends of Two Perylene Derivatives: Mesogenic Properties and Application As Emitter Materials in OLEDs VL - 60 ER - TY - JOUR AB - Switchable two dimensional liquid crystal diffraction gratings are promising can- didates in beam steering devices, multiplexers and holographic displays. For these areas of applications a high degree of integration in optical systems is much sought-after. In the context of diffraction gratings this means that the angle of diffraction should be rather high, which typically poses a problem as the fabrication of small grating periods is challenging. In this paper, we propose the use of nanosphere lithography (NSL) for the fabrication of two-dimensionally structured electrodes with a periodicity of a few micrometers. NSL is based on the self-assembly of micro- or nanometer sized spheres into monolayers. It allows for easy substrate structuring on wafer scale. The manufactured electrode is combined with a liquid crystalline polymer-stabilized blue phase, which facilitates sub-millisecond electrical switching of the diffraction efficiency at adiffractionangle of 21.4°. AU - Wahle, M. AU - Brassat, Katharina AU - Ebel, J. AU - Bürger, Julius AU - Lindner, Jörg AU - Kitzerow, Heinz-Siegfried ID - 3997 IS - 19 JF - Optics Express 25 TI - Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography VL - 25 ER - TY - JOUR AU - Vollbrecht, Joachim AU - Wiebeler, Christian AU - Schumacher, Stefan AU - Bock, Harald AU - Kitzerow, Heinz-Siegfried ID - 13358 JF - Molecular Crystals and Liquid Crystals SN - 1542-1406 TI - Enhanced columnar mesophase range through distortions in arene cores ER -