Alignment of a Columnar Hexagonal Discotic Liquid Crystal on Self-Assembled Monolayers

Al-Lawati, Zuhoor H.; Bushby, Richard J.; Evans, Stephen D.

doi:10.1021/jp3111056

Cited by 25 publications

(17 citation statements)

References 65 publications

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“…42,43 This method depends on the chemical structure of the molecule and therefore would be considered to be a chemical alignment method. 42,43 This method depends on the chemical structure of the molecule and therefore would be considered to be a chemical alignment method.…”

Section: Methods To Prepare Aligned Films For Polarised Emissionmentioning

confidence: 99%

Recent progress in luminescent liquid crystal materials: design, properties and application for linearly polarised emission

et al. 2015

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Luminescent liquid crystals (LCs) materials have attracted significant interests for organic optoelectronic applications, especially for linearly polarised emission, becaused of their combination of ordered alignment and luminescence property. Since the first polarised organic light-emitting diodes (OLEDs) demonstration in 1995, remarkable progress has been done with polarised electroluminescence because of continuous advances with the design of suitable LC materials. In this Review, we summarize luminescent LC materials with representative examples based on fluorescent materials, phosphorescent materials, and lanthanide complexes. The structure-property relationships for polarised emission and, when available, electroluminescence of these materials are presented and discussed, with a focus on phosphorescent metallomesogens. We also present the rational behind the design and development of luminescent LCs materials for high efficiency polarised OLEDs, along with the challenges ahead to achieve efficient devices.

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Section: Methods To Prepare Aligned Films For Polarised Emissionmentioning

confidence: 99%

Recent progress in luminescent liquid crystal materials: design, properties and application for linearly polarised emission

et al. 2015

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“…In these cases, the techniques that are currently used to align nematics are ineffective. Columnar phases of DLCs are remarkably insensitive to surface chemistry or roughness 17, 18. Almost universally, they adopt a homeotropic alignment at the solid‐to‐liquid crystal interface and a planar orientation at the air‐to‐liquid crystal interface.…”

Section: Introductionmentioning

confidence: 99%

Controlled Planar Alignment of Discotic Liquid Crystals in Microchannels Made Using SU8 Photoresist

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et al. 2013

Adv Funct Materials

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achieve such uniaxial alignment but more generally reliable methods are Langmuir-Blodget deposition, [ 23 ] the use of PTFErubbed substrates, [23][24][25][26][27] zone-casting, [ 12 , 23 , 28-31 ] zone-melting [ 32 ] and alignment within channels. [ 33,34 ] 'Uniaxial planar' samples are essential for making electronic devices such as fi eld effect transisitors where it is important to ensure that the column direction, the preferred axis for conduction, runs in-plane from source to drain electrode.Very thin open fi lms of DLCs have a tendency to dewet from the surface: particularly when they are heated into the isotropic phase. On a surface patterned with alternating high and low energy stripes this dewetting produces long thin droplets (as shown schematically in cross-section in Figure 1 a). This not only enforces a planar alignment of the column director but also provides control over its in-plane orientation. [ 35 ] For some liquid crystals it lies across the droplets and in others parallel to their long axis. In this paper we show that the same sort of control can also be achieved for a range of DLCs Controlled Planar Alignment of Discotic Liquid Crystals in Microchannels Made Using SU8 PhotoresistA range of triphenylene and phthalocyanine-based discotic liquid crystals (DLCs) can be aligned within micrometer-scale channels formed from SU8 patterned on silicon or glass surfaces. The channels can be fi lled with the DLC in its isotropic phase using capillary action. Alignment occurs spontaneously as the sample is slowly cooled into the Col h phase. Whilst all of these DLCs align with the columns perpendicular to the surface when they are 'sandwiched' between glass slides, in these channels, the DLC aligns with the column director parallel to the surface. It is also constrained to lie across the channels. The same alignment occurs when these DLCs are confi ned between SU8-topped interdigitated gold electrodes where it gives the optimum orientation for electrode-to-electrode conduction. The quality of the alignment depends on the particular liquid crystal used and on the width of the channel. For the Col r phase of octaoctylphthalocyanine there is additional epitaxial control over the orientation of the lattice such that the a/c face of the lattice is parallel to the surface. This is an important prerequisite for creating a bistable display device that switches by virtue of changing the direction of the tilt of the discs.

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Section: Resultsmentioning

confidence: 99%

“…Since the physical properties of discotics that are essential for device applications can be tailored, the alignment of molecules in thin films has been an important topic of research over the past several decades. [32][33][34] Depending upon the molecule-molecule and molecule-substrate interactions, discotics are known to exhibit interesting molecular conformations on a substrate. Perova et al observed the anchoring transition (similar to the local Fredericks transition) in discotic liquid crystals from the edge-on to the face-on (side-on) alignment for a number of substrates both untreated and coated with polymer.…”

Section: Langmuir-blodgett (Lb) Film Depositionmentioning

confidence: 99%

Supramolecular Self‐Assembly of Ionic Discotic Liquid Crystalline Dimer with DNA at Interfaces

et al. 2018

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Nanoarchitectonics through ionic self‐assembly at interfaces is an attractive approach to obtain advanced functional materials. Here, a novel discotic dimer‐DNA complex hybrid system has been investigated at air‐water and air‐solid interfaces. The ionic discotic liquid crystalline dimer consisted of two triphenylene cores linked via alkyl spacer with a imidazolium moiety. At air‐water interface, the dimer formed a stable monolayer with a reversible collapse. The surface manometry results suggested that the condensed phase of the monolayer consisted of molecules arranged in an edge‐on conformation. To understand the folding behavior of the molecules, DFT calculations were carried out which showed that the quantum chemically optimized folded‐form of the molecule was electronically more stable than its unfolded‐form. Upon adding DNA to the subphase, a complex monolayer was formed with enhanced stability as was indicated by increased collapse pressure and decreased limiting area. Importantly, this complexation enabled an efficient and stable multilayer formation on silicon substrates with layers as many as 40. Since both DNA and discotic dimer molecules share common properties of one‐dimensional charge transport with compatible structures, this complex film could serve as a model system for organic electronics.

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Alignment of a Columnar Hexagonal Discotic Liquid Crystal on Self-Assembled Monolayers

Cited by 25 publications

References 65 publications

Recent progress in luminescent liquid crystal materials: design, properties and application for linearly polarised emission

Recent progress in luminescent liquid crystal materials: design, properties and application for linearly polarised emission

Controlled Planar Alignment of Discotic Liquid Crystals in Microchannels Made Using SU8 Photoresist

Supramolecular Self‐Assembly of Ionic Discotic Liquid Crystalline Dimer with DNA at Interfaces

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