The doping of the polyimide alignment layer by semiconductor quantum dots

Konshina, E. A.; Galin, I.; Gavrish, E. O.; Vakulin, D. A.

doi:10.1063/1.4817826

Cited by 6 publications

(2 citation statements)

References 13 publications

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“…This was attributed to the self-organization of the q-dots. In a more recent study [44], CdSe/ZnS q-dots were incorporated into the homogeneously aligning polyimide layer of NLC cells. The authors confirmed reduced ε, ΔΦ, slower optical response, and increased electrical resistance with no visible changes in V th .…”

Section: Effects Of Quantum-dots On Liquid Crystal Physical Propertiesmentioning

confidence: 99%

Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review

2016

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Investigations of the mixtures of semiconducting quantum scale particles in anisotropic liquid crystal (LC) medium have become a vibrant area of research primarily due to their very interesting phenomenology. The results of these investigations fall into four groups: (i) Photoluminescent emissive properties of the quantum particles ordinarily depend on the size, shape, and chemical nature of the particles. These undergo important changes in their spectrum, polarization, and isotropy of emission when dissolved in an anisotropic LC phase. Moreover, their response to external stimuli such as mechanical, optical, or electric fields is altered in important ways; (ii) physical properties of LCs such as viscosity, dielectric relaxation, etc are modified by the addition of quantum particles. Their presence in ferroelectric smectic LC is known to give rise to an antiferro- to ferri-electric phase transition and suppresses the paraelectric phase; (iii) switching characteristics of LC devices are altered in important ways by the addition of quantum particles. Their threshold voltage is usually lowered, contrast ratio, and switching speed of nematic, ferroelectric, and cholesteric devices may increase or decrease depending on the concentration, applied field, and particle anisotropy; and (iv) controlled aggregation of quantum particles at the interface between isotropic and LC domains, near added polystyrene beads, and in the vicinity of point defects gives rise to interesting photonic structures, enables studies of photon antibunching and single photon sources. Clearly, there is a need to understand the basic and applied aspects of these systems and find routes to their technological applications including sensors, electrooptical devices, and solar energy harvesting. This review provides an overview of recent work involving liquid crystals and a variety of quantum particles.

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Section: Effects Of Quantum-dots On Liquid Crystal Physical Propertiesmentioning

confidence: 99%

Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review

2016

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“…In general, the long‐chain organic ligands are used to protect/functionalize the surface and increase the steric repulsion of semiconductor QRs. It was observed that in the QR/LCM composite systems, the interaction of the QR ligands with the molecular LC matrix often leads to topological defects in the QRs/LCP composite films, which also depends on the concentrations of both nanoparticles and LCM in solution . On one hand, for the low concentration of LC molecules, the orientational forces do not notably contribute to the aggregation process, but the interaction due to the change of the order parameter near the QR surface plays an important role .…”

Section: Introductionmentioning

confidence: 99%

Formulation of a Composite System of Liquid Crystals and Light‐Emitting Semiconductor Quantum Rods: From Assemblies in Solution to Photoaligned Films

Dudka

Zhang

Schneider

et al. 2019

Adv Materials Technologies

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QRs), [4,5] have been considered as promising light-emitting components in modern display, lighting, bioimaging, and photonics applications. [6][7][8][9][10][11][12][13][14][15][16] Based on the quantum-confinement effect, these nanocrystals possess outstanding optical properties, such as precisely tunable emission, narrow emission bandwidths, high photoluminescence (PL) quantum yields (QYs), and better photostability compared to molecular dyes. [17][18][19] In addition, 1D anisotropic nanocrystals, such as CdSe/CdS core/shell QRs with a dot-in-rod geometry, show strongly polarized absorption and emission along the long axis of the QR. [20][21][22] The ability of strongly emitting semiconductor QR, when macroscopically aligned, to emit linearly polarized light makes them perfect candidate for liquid crystal display (LCD) backlights. To translate their anisotropic properties from a single nanocrystal to the macroscopically polarized lightemitting materials, QRs need to be oriented unidirectionally in plane, which can be achieved by several assembly approaches. [23][24][25][26][27] Our previous work has introduced photoinduced alignment of QRs in a liquid crystal polymer (LCP) matrix as a strategy to control QR orientation from centimeter [28] down to micrometer domain sizes. [29] By utilizing the photoactive sulfonic azo dye as an alignment layer, photo alignment is transferred to the liquid crystal monomers (LCM), whose reorientation results in torque that is transferred to the QRs through the repulsive interactions with the QR capping ligands. In general, the longchain organic ligands are used to protect/functionalize the surface and increase the steric repulsion of semiconductor QRs. It was observed that in the QR/LCM composite systems, the interaction of the QR ligands with the molecular LC matrix often leads to topological defects in the QRs/LCP composite films, which also depends on the concentrations of both nanoparticles and LCM in solution. [30][31][32][33][34] On one hand, for the low concentration of LC molecules, the orientational forces do not notably contribute to the aggregation process, but the interaction due to the change of the order parameter near the QR surface plays an important role. [35,36] This process also induces deformation of the LC director along the surface of the colloid The ability of strongly emitting semiconductor quantum rods (QRs), when macroscopically aligned, to emit linearly polarized light makes them the perfect candidate for liquid crystal (LC) display backlights. Macroscopic QR ordering is previously demonstrated by photoalignment of QR composites with polymerizable LC monomers. In this study, it is demonstrated that the optimum concentration of LC monomers and core/shell CdSe/CdS QRs enabling someone to achieve their uniform homogeneous orientation in photoaligned films strongly depends on the lengths and aspect ratios of the QRs. By aligning QRs with different aspect ratios ranging from 3 to 10, the best performance is achieved for shorter QRs with lengths of 11 and 31 ...

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Recent advances and future perspectives on nanoparticles-controlled alignment of liquid crystals for displays and other photonic devices

Priscilla

Malik

Supreet

et al. 2022

Critical Reviews in Solid State and Materials Sciences

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The doping of the polyimide alignment layer by semiconductor quantum dots

Cited by 6 publications

References 13 publications

Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review

Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review

Formulation of a Composite System of Liquid Crystals and Light‐Emitting Semiconductor Quantum Rods: From Assemblies in Solution to Photoaligned Films

Recent advances and future perspectives on nanoparticles-controlled alignment of liquid crystals for displays and other photonic devices

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