References of "Journal of Materials Chemistry C"
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See detailWhy organically functionalized nanoparticles increase the electrical conductivity of nematic liquid crystal dispersions
Urbanski, Martin; Lagerwall, Jan UL

in Journal of Materials Chemistry C (2017), 5(34), 8802-8809

Doping liquid crystals with gold nanoparticles increases the conductivity by up to three orders of magnitude, an increase even stronger than expected for equimolar amounts of organic electrolytes. Despite ... [more ▼]

Doping liquid crystals with gold nanoparticles increases the conductivity by up to three orders of magnitude, an increase even stronger than expected for equimolar amounts of organic electrolytes. Despite recent high activity in the field of liquid crystalline nanocomposites, the origin of this increase has rarely been addressed and is not well understood. In this dielectric spectroscopy study we discuss the origin of the increased conductivity and identify its source. We demonstrate that the hydrodynamic radius of the mobile charge carrier species in nanoparticle dispersions is significantly smaller than the 3–5 nm gold core, which rules out the particles themselves to be the source of conductivity. Likewise, also the ligand molecules from the organic capping layer do not themselves add to the conductivity of the dispersions, but affect the electrical properties by acting as a trap for ionic impurities. We suggest that the partial release of these impurities upon interactions of the ligand shell with the uniaxial nematic host phase is the most likely source for the increased conductivity. Our study opens a new perspective on synthesis strategies for functionalized nanoparticles and will help to overcome the current issues preventing high-performing liquid crystal nanodispersions. [less ▲]

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See detailNanoparticles dispersed in liquid crystals: impact on conductivity, low-frequency relaxation and electro-optical performance
Urbanski, Martin UL; Lagerwall, Jan UL

in Journal of Materials Chemistry C (2016), 4(16), 3485-3491

We study the impact of functionalized gold nanoparticles on the impedance response of nematic nanoparticle/liquid crystal dispersions in the frequency range of 0.1 Hz–100 kHz. By fitting a suitable ... [more ▼]

We study the impact of functionalized gold nanoparticles on the impedance response of nematic nanoparticle/liquid crystal dispersions in the frequency range of 0.1 Hz–100 kHz. By fitting a suitable equivalent electric circuit model to the experimental data we show that nanoparticle doping does not affect the permittivity of the nematic host, but significantly increases its conductivity. This causes a Debye-type relaxation process in the Hz and low kHz regime, which originates from mobile charge carriers accumulating near the electrodes of the test cell. The effect of this electrode polarization on the electro-optical response of the nanocomposites is discussed with respect to threshold voltage and dielectric permittivity. We demonstrate that nanoparticle doping does not alter the electro-optic response at frequencies above the occurrence of electrode polarization, while it strongly deteriorates the performance in the low frequency regime. [less ▲]

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See detailLaser annealing of electrodeposited CuInSe2 Semiconductor Precursors: Experiment and Modeling
Meadows, Helen UL; Misra S.; Simonds B. J. et al

in Journal of Materials Chemistry C (2016)

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See detailTransparent conductive CuCrO2 thin films deposited by pulsed injection metal organic chemical vapor deposition: up-scalable process technology for an improved transparency/conductivity trade-off
Crêpellière J.; Lunca Popa P.; Bahlawane N. et al

in Journal of Materials Chemistry C (2016)

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See detailMultifunctional responsive fibers produced by dual liquid crystal core electrospinning
Kye, Yoomee; Kim, Changsoon; Lagerwall, Jan UL

in Journal of Materials Chemistry C (2015), 3

We demonstrate that coaxial electrospinning with more than one core channel, each containing a different type of liquid crystal, can be used to produce multifunctional fibers in a one-step process. They ... [more ▼]

We demonstrate that coaxial electrospinning with more than one core channel, each containing a different type of liquid crystal, can be used to produce multifunctional fibers in a one-step process. They respond to more than one stimulus or with multiple threshold values, and the individual cores may feature different physical properties such as iridescent reflection in one core and birefringence in another. In order to ensure good fiber morphology and intact, unmixed and well separated cores, two important precautions must be taken. First, the fibers should not be collected on a hydrophilic substrate, as this will lead to severe fiber deformation and core mixing after collection, as a result of capillary forces from the water that condenses on the fiber during spinning. Second, the addition of surfactants to the polymer solution should be avoided, although it may appear beneficial for the spinning process as it reduces surface tension and increases conductivity. This is because the surfactant enters the liquid crystal core, possibly together with water in the form of inverse micelles, seriously degrading the performance of the liquid crystal. [less ▲]

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See detailElectrochemical deposition as a unique solution processing method for insoluble organic optoelectronic materials†
Allwright, Emily; Berg, Dominik UL; Djemour, Rabie UL et al

in Journal of Materials Chemistry C (2014), 2

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See detailTuneable Multicoloured Patterns From Photonic Cross Communication Between Cholesteric Liquid Crystal Droplets
Noh, Junghyun UL; Liang, Hsin-Ling; Drevensek-Olenik, Irena et al

in Journal of Materials Chemistry C (2014), 2(5), 806-810

Monodisperse droplets of planar-aligned cholesteric (N*) liquid crystal exhibit an intriguing capacity for photonic cross-communication, giving rise to colourful patterns that depend sensitively on the N ... [more ▼]

Monodisperse droplets of planar-aligned cholesteric (N*) liquid crystal exhibit an intriguing capacity for photonic cross-communication, giving rise to colourful patterns that depend sensitively on the N* pitch, droplet positions and illuminated area. The phenomenon results from a combination of omnidirectional selective reflection of N* droplets—which thus act as spherically symmetric self-assembled photonic crystals—and total internal reflection at the continuous phase surface. We outline how the unique optical properties can be employed in numerous applications. [less ▲]

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