Device including ferroelectric nematic liquid crystal-forming molecules and methods of forming and using same
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Solution Overview
Problem
Existing nematic liquid crystal technologies require high electric or magnetic fields for director reorientation, and surface interactions are primarily quadrupolar, limiting their responsiveness and efficiency.
Innovation Solution
Employing ferroelectric nematic liquid crystals with a spontaneous polarization that couples linearly to applied fields, and using surfaces with controlled polarity to achieve vectoral orientation without the need for strong external fields, enabling faster and more predictable reorientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional nematic liquid crystals are used with quadrupolar surface interactions, then device structure can be achieved, but high electric or magnetic fields are required for director reorientation
Solution Approach 1:
The patent changes the fundamental parameter of liquid crystal polarity from nonpolar (conventional nematic) to polar (ferroelectric nematic). This parameter change enables linear coupling between molecular dipoles and applied electric fields, eliminating the need for high fields (thousands of V/cm) required by quadrupolar coupling in conventional nematic liquid crystals.
Solution Approach 2:
The patent employs a composite approach by combining ferroelectric nematic liquid crystal materials with polar surface treatments. This creates a system where both bulk and surface interactions are polar in nature, enabling coherent control of director orientation through dipolar coupling rather than requiring high-field quadrupolar interactions.
2Ease of operation
If conventional nematic liquid crystals with quadrupolar surface interactions are used, then alignment can be achieved, but surface interactions are limited in responsiveness
Solution Approach 1:
The patent changes the surface interaction parameter from quadrupolar to polar by implementing polar surface treatments. This enables direct dipolar coupling between the polar liquid crystal molecules and the polarized surfaces, significantly enhancing responsiveness and allowing precise alignment control at low field strengths.
3Force
If high electric fields are applied to conventional nematic liquid crystals for director reorientation, then reorientation can be achieved, but response time is limited
Solution Approach 1:
The patent changes the coupling mechanism parameter from quadrupolar to dipolar interaction. This fundamental parameter change enables much faster response times because dipolar coupling is inherently stronger and more direct than quadrupolar coupling, allowing rapid director reorientation at low field strengths without the time losses associated with high-field applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ferroelectric nematic liquid crystals achieve director reorientation with fields as low as 1 V/cm, allowing for faster electro-optic responses and stable monodomain ordering without the need for high poling fields, enhancing device performance.
Implementation Method 1
A novel nematic liquid crystal phase has recently been shown to be a ferroelectric nematic (NF), offering a variety of opportunities to employ LC field and surface phenomena in exciting and powerful new ways. The NF LC is a 3D liquid having a macroscopic electric polarization P(r).
Implementation Method 2
The polarization thus endows the NF with coupling between n(r) and applied electric field, E, that is linear and is dominant over the dielectric coupling at low E.
Implementation Method 3
The resulting large spontaneous polarization, P∼6 μC/cm2, enables field-induced nematic director reorientation and an associated electro-optic (EO) response with fields applied in typical cells as small as ∼1 V/cm, a thousand times smaller than those that comparably reorient dielectric nematics.
Implementation Method 4
The one or more surfaces can be configured to impart a favored surface polarity of the molecules, said favored surface polarity controlling said vectoral orientation at the interfaces with the one or more surfaces.
Data Source
AI summary
Surface polarity of a ferroelectric nematic can be configured to generate vectorial control of the orientation of its bulk polarization field. The contact between a surface with in-plane polarity and a ferroelectric nematic liquid crystal generates preferred in-plane orientation of the ferroelectric polarization field at that interface, which can lead to the formation of fluid or glassy monodomains of high polarization without electric field poling. Materials surfaces can be used as a route to making planar-aligned cells with a variety of azimuthal director/polarization structures, including twisted states, in a π-twist cell, obtained with antiparallel, unidirectional buffing on opposing surfaces, we demonstrate three distinct modes of ferroelectric nematic electro-optic response: intrinsic viscosity-limited field induced molecular reorientation, field-induced motion of domain walls separating twisted states of opposite chirality; and propagation of polarization reorientation solitons from the cell plates to the cell center upon field reversal.