Charge control devices and methods of forming and using same - Patents.com

Abstract

A device is disclosed that includes a volume containing a ferroelectric nematic liquid crystal material, a dielectric layer covering a portion of the volume, and a charge carrying substrate or layer. Methods of forming and using such a device are also disclosed.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 278,047, filed November 10, 2021, and entitled CHARGE-CONTROLLED DEVICES AND METHODS OF FORMING AND USING SAME, the contents of which are hereby incorporated by reference herein to the extent such content is not inconsistent with this disclosure. Federally Sponsored Research This invention was made with Government support under Grant No. DMR1710711 awarded by the National Science Foundation. The Government has certain rights in this invention. Field of the Disclosure The present disclosure relates generally to devices containing ferroelectric nematic liquid crystal materials and methods for controlling the molecular orientation of ferroelectric nematic liquid crystals within a volume. [Background technology]

[0002] Nematic liquid crystals are materials of anisotropically shaped molecules or particles that can achieve uniform mutual orientation when they are packed together in a condensed phase. For example, rod-shaped molecules can be oriented with their long axes tending to align locally along a common direction. This orientational ordering has the beneficial effect of making the material optically anisotropic (birefringent) and enhancing its response to the application of external influences such as electric or magnetic fields. Such responsive liquid crystals can be widely useful in a variety of applications. Nematic liquid crystals may be liquid, viscoelastic, or glassy, ​​and may be made from molecular species that are monomeric, oligomeric, or polymeric. For the purposes of this disclosure, these various types of partially fluid, partially solid liquid crystal materials are referred to as "nematic" and "fluid."

[0003] In addition to their three-dimensional rod-like shape (e.g., like a hot dog), molecules that create nematic liquid crystal phases may have one end of a different polarity than the other (e.g., like a baseball bat or an arrow). Molecular polarity may be introduced, for example, by adopting an internal molecular structure in which the internal charge distribution within the molecule is not spatially uniform, but rather is "dipole", with separate regions (dipoles) of excess positive or negative charge. Molecules with dipoles have the potential for an additional type of ordering (polar ordering), in which the molecular arrows point in the same direction. For example, rod-shaped molecules with dipole arrows along their long axes can spontaneously order with the dipoles parallel and all in the same direction, like arrows in a quiver or an arrow stuck in a target. When such ordering occurs in nematic liquid crystals, the resulting material can be optimally said to be "ferroelectric".

[0004] Ferroelectric fluids are interesting because recent modeling suggests that by having an optimal common dipole orientation, the response of the fluid to an applied electric field can be much greater than the response of a fluid that lacks polar ordering: for example, the molecules should change orientation in response to an applied voltage at a much lower voltage.

[0005] Any discussion, including discussion of the problems and solutions described in this section, is included in this disclosure solely for the purpose of providing a context for the disclosure, and such discussion should not be construed as an admission that any or all of the information was publicly known or otherwise constitutes prior art at the time the invention was made. Summary of the Invention

[0006] This Summary is provided to introduce selected concepts. This Summary does not necessarily identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0007] Various embodiments of the present disclosure relate to devices that include a volume containing a ferroelectric nematic liquid crystal material, one or more dielectric layers, and one or more charge carrying substrates, and methods of forming and using the same. Exemplary embodiments further relate to sensors, actuators, and the like that include such devices, and methods of using the same.

[0008] According to examples of the present disclosure, a device includes a volume containing a ferroelectric nematic liquid crystal material, a dielectric layer covering at least a portion of the volume, and a charge carrying substrate covering at least a portion of the dielectric layer. The volume includes a polarization charge adjacent to the dielectric layer that is controllable by a charge applied on and / or to the charge carrying substrate. In some cases, the device may include one or more additional dielectric layers covering the volume. In such cases, the device may include one or more additional charge carrying substrates covering the one or more additional dielectric layers. Various examples of dielectric layer materials and charge carrying substrate materials are provided below.

[0009] By way of further examples, sensors, actuators, electro-optical devices, photonic devices, non-linear optical devices, ferroelectric memory devices, or dual-function information storage and processing devices are formed using or include the devices described herein.

[0010] According to yet a further example, there is provided a method of controlling molecular orientation of ferroelectric nematic liquid crystal within a volume containing said liquid crystal by forming charge on and / or altering charge on one or more surfaces at least partially bounding said volume, thereby forming polarization charges within the volume and proximate to the one or more surfaces.

[0011] These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying figures. The invention is not limited to any particular embodiment disclosed.

[0012] A more complete understanding of the embodiments of the present disclosure can be derived by reference to the detailed description and claims when considered in conjunction with the following illustrative figures. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1A shows (A) the geometry of a planar aligned NF cell (device) of area A showing the charge-controlled block polarization response to applied voltage, (B) a cross-section of the cell showing the LC and dielectric layers, electrodes, NF polarization P, polarization orientation Ψ, free charges, and polarization charge (P), and (C) the electrical equivalent circuit of the cell according to an example of the present disclosure. [Diagram 2] FIG. 2 illustrates a ferroelectric nematic liquid crystal electro-optical cell (device) with in-plane electrodes according to an example of the present disclosure. [Diagram 3] FIG. 1 shows a schematic diagram of a volumetrically controlled dynamic grating device according to the present disclosure. [Figure 4] FIG. 1 illustrates a top view of a simulated charge-controlled Pancharatnam phase device according to an example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] It is understood that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale, for example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the illustrated embodiments of the present disclosure.

[0015] The descriptions of exemplary embodiments provided below are merely exemplary and for purposes of explanation only, and the following descriptions are not intended to limit the scope of the present disclosure or the claims. Moreover, the description of multiple embodiments having described features does not exclude other embodiments having additional features or other embodiments incorporating different combinations of the described features.

[0016] In this disclosure, any two numbers of a variable may constitute a workable range for the variable, and any range stated may include or exclude the endpoints. Furthermore, any value of a variable stated (whether or not stated as "about") may refer to an exact value or an approximation, including equivalents, and may refer to the mean, median, representative value, majority, value ±10% (e.g., vol.at. or mass%), etc. Furthermore, in this disclosure, the terms "comprise", "comprise", and "have" or similar words may independently refer to "typically or broadly include", "comprise", "consist essentially of", or "consist of" in some embodiments. In this disclosure, any defined meaning does not necessarily exclude the ordinary and accustomed meaning.

[0017] Furthermore, in some embodiments, a layer refers to a structure having a certain thickness formed on a surface, or a synonym for a film or non-film structure. A layer may be continuous or non-continuous. A film or layer may be composed of a discrete single film or layer or multiple films or layers having specific characteristics, and the boundaries between adjacent films or layers may or may not be clear, and may or may not be established based on the physical, chemical and / or any other characteristics, formation process or sequence, and / or function or purpose of adjacent films or layers. In some cases, a substrate may refer to a film deposited or otherwise on another material.

[0018] Referring now to the figures, Figure 1 shows a device 100 according to an example of the present disclosure. The device 100 includes a volume 102 containing a ferroelectric nematic liquid crystal material, and surfaces bounding said volume, where the orientation of molecules in said ferroelectric nematic material is controlled by varying the charge at said interface. The device 100 further includes one or more dielectric layers 104, 106, and one or more charge-carrying substrates 108, 110. The device 100 may also include a charge or bias source 112 and a ground connection 114.

[0019] According to examples of the present disclosure, the surface bounding the volume 102 of ferroelectric nematic material is a capacitive interface that includes a dielectric layer (e.g., dielectric layer 104 or 106) between the outer surface of the ferroelectric nematic liquid crystal and the inner surface of a substrate, such as charge-carrying substrate 108 or 110. This interface forms part of a capacitor, where the bound polarized surface charge on the inner (liquid crystal / volume 102) side of the capacitor is controlled by a charge placed on the outer (substrate) side of the capacitor, for example, using charge source 112. As a result, the orientation of the molecules of the ferroelectric nematic volume 102 inside the capacitor is controlled by a charge placed on the outside of the capacitor, since the polarized surface charge density at the surface of the ferroelectric nematic depends on the orientation of the polar molecules at that surface.

[0020] As shown in Figure 1, the so-called "V-shaped" or "block polarization" switching may be understood as a charge or capacitance controlled process in which the polarization field of a ferroelectric liquid crystal reorients uniformly (as a "block") under an applied voltage, and the orientation Ψ of the polarization vector relative to the normal to the interface can be determined by the relationship Ψ(V) = cos -1 (C I V / PA) where V is the applied voltage and C Iis dominated by the capacitance of the dielectric (e.g., insulating) layer at the electrode surface through (Ψ is the capacitance of the dielectric layer (interfacial capacitance), P is the magnitude of the ferroelectric polarization density, and A is the area of ​​the sandwich cell). This may be viewed as a charge compensation effect, where the orientation Ψ is determined by the condition that the polarized surface charge density at the liquid crystal-insulator interface is equal in magnitude and opposite in sign to the free charge density at the adjacent insulator-electrode interface, resulting in an analog response that depends on the applied voltage and the capacitance of the dielectric layer. If the dielectric layers 104, 106 are insulating (i.e., have low electrical conductivity), the polarization field of the ferroelectric material may be "latched" into a particular orientation that is maintained over long timescales under open circuit conditions after a given surface charge density is deposited on the electrodes. Such devices can thus function as both light processing elements and continuously multistable memory elements, with potential applications in neuromorphic computing. Multistability may also lead to reduced power consumption in devices based on ferroelectric nematics.

[0021] The mode of operation of these devices is qualitatively different from devices based on conventional nematic liquid crystals. In conventional nematic devices, free charges placed on electrodes adjacent to the nematic material generate an electric field within the volume of the nematic liquid crystal, which couples to the dielectric anisotropy of the nematic material within that volume, resulting in a torque that reorients the nematic liquid crystal. In contrast, highly polarized ferroelectric nematic liquid crystals exhibit two distinct regimes: for small applied voltages, the response is charge-controlled, with a uniform molecular reorientation in the bulk (the "block polarization response") driven by electrostatically controlled molecular reorientation at the surface. In this electrostatic energy-dominated limit, where the molecular orientation at the surface generates polarized surface charges that screen the free charges placed on the electrodes, the electric field is primarily confined to the capacitive interfaces, and the field within the volume of the liquid crystal is small up to a threshold charge density equal to the ferroelectric polarization density of the material. In the high voltage regime, during dynamic switching, an electric field appears within the volume of the ferroelectric nematic that couples to the ferroelectric polarization density within the volume, resulting in a torque that reorients the ferroelectric nematic liquid crystal until the free charges on the electrodes are completely screened. This linear ferroelectric coupling can result in an electro-optic response that is 2-3 orders of magnitude faster than conventional nematic devices under comparable applied voltages. See WO2021 / 178587, the contents of which are hereby incorporated by reference herein to the extent such content is not inconsistent with the present disclosure.

[0022] With continued reference to FIG. 1, FIG. 1(A) illustrates a planar array N of area A showing the charge-controlled block polarization response to an applied voltage. F The geometry of the cell is shown in Fig. 1(B). Fig. 1(B) shows a cross section of the cell, including the LC and dielectric layers 104, 106, the charge carrying substrates 108, 110 (e.g. electrodes), the N F Polarization P, polarization orientation Ψ, free charge, and polarization charge (P) are shown. In the limit where polarization P = |P| is large, electrostatic self-shielding makes the polarization field uniform and the polarization charge is drained to the LC surface. Applied voltage |V| <V sat =2d I P / ε I When , the polarization P reorients as a homogeneous block, eliminating the electric field from the liquid crystal. Figure 1(C) shows the electrical equivalent circuit of the cell. In the example shown, NF The volume 102 has a resistivity ρLC =γ / P 2 This layer behaves electrically like a resistor with a capacitance C I C LC is the dielectric response in the absence of P influence, F represents the "bare" capacitance of d LC >>d I If C LC < <C I In this case, C LC makes a negligible contribution to the electric field response.

[0023] Charge-controlled ferroelectric nematic devices such as device 100 may be static, with a time-independent polarization field imposed by a fixed charge distribution on the interface, or dynamic, with a time-varying polarization field that is responsive to a time-varying charge distribution on the interface (e.g., in electro-optical devices). Dynamic charge distributions may be realized in capacitive interfaces that are simultaneously conductive and dielectric, or in photoresponsive devices where a dynamic charge distribution is generated by a photoconductive substrate or dielectric layer.

[0024] Charge-controlled ferroelectric nematic devices such as device 100 may include a wide variety of shapes and materials and may utilize a variety of methods for depositing charge at the interface. The interface substrates (e.g., charge-carrying substrates 108, 110) and / or other substrates and / or dielectric layers may be crystalline or glassy solids, fluids, or soft materials such as polymers, gels, or emulsions.

[0025] Volume 102 can include molecules with one or more electric dipoles. Exemplary molecules for volume 102 may include, for example, (1) a rod shape suitable for nematic liquid crystal ordering; (2) a substantial molecular net dipole parallel to the long axis of the molecule, said dipole stabilizing the head-to-tail chain of said rod-shaped molecules; (3) molecular subcomponents along the length of the molecule that provide localized charges distributed along the long axis of the molecule, said charges interacting with opposite charges; (4) a minimally flexible tail that allows dipolar charges to interact, but provides sufficient flexibility to inhibit crystallization, and / or (5) side groups to control the relative position along the director of parallel molecules to promote polar order. By way of example, the molecule may include 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate, a rod-shaped molecule with a large electric dipole moment parallel to its long axis. The thickness of the volume 102 can range from about 10 nm to about 1 cm, or from about 2 micrometers to about 100 micrometers.

[0026] According to examples of the present disclosure, the dielectric layers 104, 106 may be or include an insulator, a layer of finite conductivity, a semiconductor, a self-assembled monolayer, an insulating oxide layer, a photoconductor, or a semiconductor depletion layer. For example, the dielectric layers 104, 106 may be or include an oxide layer or other dielectric layer on a conductive (e.g., metal) charge-carrying substrate (electrode (e.g., aluminum)), a self-assembled monolayer on a metal electrode (e.g., gold), a semiconductor depletion layer, an electrolyte, etc. The dielectric layer may additionally or alternatively be intrinsic to a ferroelectric nematic material that includes a thin surface layer in which the orientation of the polarization is fixed by surface interactions. The thickness of the dielectric layers 104, 106 may vary, for example, from about 0.1 nm to about 10 micrometers, or from about 1 nm to about 30 nm.

[0027] In some cases, the dielectric layer includes an alignment layer that orients the ferroelectric nematic molecules near the surface, hi some cases, each surface that bounds the ferroelectric nematic liquid crystal includes a dielectric layer adjacent the liquid crystal and an adjacent charge carrying substrate, and each surface has a finite capacitance and therefore functions as a capacitor.

[0028] By way of further example, the charge carrying substrates 108, 110 may be a (eg, solid) conductor, semiconductor, or insulator, a solid or liquid electrolyte, an ionic liquid, or the like. Devices in which the charge density on the interface is responsive to external fields or other stimuli, such as external electromagnetic or optical fields, chemical or electrochemical reactions, biomolecular binding events, mechanical strain or shear, and fluid flow, can be used as sensors. Biomolecular binding events may be of particular interest for sensor applications. Responses to external fields or other stimuli are detected electrically and / or optically.

[0029] According to further examples of the present disclosure, the surfaces bounding the volume 102 may include a conductive substrate spatially patterned with regions of varying capacitance, resulting in a spatially varying analog response of said ferroelectric nematic material to an applied voltage, enabling a variety of static and dynamic electro-optical and photonic effects. The spatially varying capacitance may be achieved by depositing dielectric layers of varying thickness and / or dielectric constant on the conductive surfaces bounding the volume 102 containing the ferroelectric nematic material. Under an applied voltage, capacitive coupling between the charge-carrying substrate (e.g., an electrode) and the ferroelectric nematic material generates a spatially varying, voltage-dependent ferroelectric nematic polarization field within the volume 102 containing the ferroelectric nematic material, resulting in spatial changes in the optical and / or electrical properties of the ferroelectric material, including the dielectric constant, refractive index, and nonlinear optical susceptibility. This spatially varying, voltage-dependent, analog response is the basis for a wide variety of electro-optical and photonic devices with potential applications in spatial light modulators, lidar systems, beam steering, adaptive optics, and photonic integrated circuits, to name a few, and can be realized in a variety of device geometries, including thin films of ferroelectric nematic material confined between planar conducting substrates, or waveguide structures containing ferroelectric nematic material. Dielectric layers deposited on conducting surfaces can further function as alignment layers, providing another means of controlling the ferroelectric nematic molecular orientation and polarization fields within a volume containing the ferroelectric nematic material.

[0030] The examples of the present disclosure described herein utilize methods to achieve charge control in devices based on highly polarized ferroelectric nematic liquid crystals. Another important novel feature is the patterning of the (e.g., conductive or dielectric) surfaces that confine the volume of ferroelectric nematic liquid crystal material to generate spatially varying capacitance, enabling the creation of complex high-speed electro-optical devices that utilize simple drive schemes. Further examples include the use of spatially patterned electrodes (rather than monolithic electrodes) in addition to spatially patterned dielectric layers to achieve even higher levels of device complexity and functionality.

[0031] A specific example of a high speed charge controlled device 200 based on ferroelectric nematic liquid crystals is the in-plane switching electro-optic device 200 shown in Figure 2. As shown, the device 200 can include a volume containing ferroelectric nematic liquid crystal material 202, dielectric layers 204-210, alignment layers 212, 214, glass substrates 216, 218, and charge carrying substrates 220-226. The various components of the device 102, such as the volume containing the ferroelectric nematic liquid crystal material 202, the dielectric layers 204-210, the alignment layers 212, 214 (e.g., formed on dielectric layers or substrates), and the charge carrying substrates 220-226, can be as described above.

[0032] More specifically, Figure 2 shows a device 200 with in-plane electrodes / charge-carrying substrates 220-226. Insulating confinement walls 228, 230 minimize electrohydrodynamic flow. Alignment layers 212, 214, for example rubbed at 45° to the electrodes, provide polar anchoring on both surfaces, orientationally stabilizing either the twisted or uniform director state. An applied voltage creates a charge on the electrodes, which is compensated by the surface charge of the LC. The orientation of the director (polarization) is controlled by applying an appropriate voltage to one or both of the electrode pairs.

[0033] In the illustrated example, the device 200 includes four in-plane charge carrying substrates 220-226 (e.g., electrodes) that are used to reorient the LC material in the volume 202 in the plane of the cell / device. As shown in FIG. 2(A), the surfaces of the two bordering glass plates 216, 218, spaced a few microns apart, are treated with an alignment layer such as Glymo or polyimide. As shown in FIG. 2(B), polyimide rubbed at 45° to the electrodes induces a small pretilt and provides polar anchoring on both surfaces, stabilizing either a twisted or uniform director state in the absence of an applied voltage, depending on whether they are rubbed parallel or antiparallel. The basic configuration shown in FIG. 2(B) has four independent (e.g., gold) electrodes (charge carrying substrates) arranged around the edges of a square or rectangular pixel. By applying appropriate voltages to the electrodes (e.g., using bias source 112), the directors (polarization) of the polar liquid crystals can be oriented in any desired direction. For example, a voltage applied between the east and west electrodes (Figure 2(B)) will orient the director horizontally, whereas connecting the north and east and the south and west (Figure 2(C)) will orient it at 45° to the electrodes along the rubbing direction. The capacitance effect of the electrodes can be controlled by coating the electrodes with a very thin dielectric layer, such as an alkanethiol self-assembled monolayer (SAM), prior to assembling the cell.

[0034] Another example of a charge control device 300 is shown in FIG. 3. The device 300 includes a volume containing a ferroelectric nematic liquid crystal material 302, dielectric layers 304, 306, charge carrying substrates 308, 310, and glass substrates 312, 314. Such components are as described above. In the illustrated example, the ferroelectric nematic polarization field is uniform planar in the absence of an applied voltage in FIG. 3(A), but becomes non-uniform in the presence of an applied voltage in FIG. 3(B), exhibiting a periodically varying effective refractive index for normally incident electromagnetic radiation. Thus, the device is non-diffracting in the absence of an applied voltage and functions as a voltage-tunable diffractive element for a finite applied voltage. Exemplary applied voltages may be as described elsewhere herein.

[0035] Device 300 may be a dynamic diffraction grating comprising a thin layer of ferroelectric nematic material confined between two (e.g., ITO on glass) substrates, with a pattern of lines of varying capacitance deposited on the two substrates, where the polar director field of the ferroelectric layer is uniform planar in the absence of an applied voltage, becomes non-uniform in the presence of an applied voltage, and exhibits an effective refractive index that varies periodically for normally incident electromagnetic radiation E(w) along k, as shown in FIG. 3. Thus, device 300 is non-diffracting in the absence of an applied voltage, and functions as a voltage-tunable diffractive element for a finite applied voltage. Exemplary voltages may range from 0.01 to about 100 V, or from about 1.5 to about 5 V.

[0036] A wide variety of other charge-controlled electro-optical devices are possible. For example, with more complex spatial patterning of the insulating layer and two sets of electrodes, a tunable Pancharatnam phase beam steering device 400 can be realized, as shown in Figure 4. Such a device can diffract light into a single diffraction mode with high efficiency, and by utilizing ferroelectric nematic materials can provide high speed beam steering that is approximately 100-1000 times faster than devices based on conventional nematic materials.

[0037] Figure 4 shows the response of N F FIG. 4(A) shows a top view of a simulated charge-controlled Pancharatnam phase device 400 illustrating thin-film switching. In the absence of an applied voltage, the polarization field P(y) contains a periodic array of stripes oriented alternately along the −x and +x directions, and has a wave vector q y = 2π / λ. Such a structure is called N F This can be achieved by buffing the thin film in one direction with periodically varying stripes of width λ / 2 in the alignment layer adjacent to the thin film, where the buffing direction alternates between -x and +x. In the presence of a sinusoidal charge density wave, N FThe polarization field switches to a state where the orientation of P varies linearly with y, as shown in Figure 4(C), realizing the continuously varying optical phase delay required for the Pancharatnam phase beam steering device. In this regime, regions of high charge density induce splay of P, resulting in a periodic splay-bend modulation. The periodic charge density wave is then transformed into a N F It may be generated by a voltage applied to an array of interdigitated electrodes with pitch λ on a substrate adjacent to the thin film. For a periodicity of λ = 10 μm, numerical simulations show that switching between the on and off states occurs on a time scale of about 100 ns.

[0038] Another family of exemplary capacitance-controlled ferroelectric nematic liquid crystal devices utilizes dynamic photonic band gap structures. One example of such a device is a waveguide containing ferroelectric nematic material, whose conductive surface is coated with an insulating layer patterned to produce a capacitance that varies periodically along the length of the waveguide, with a period comparable to the wavelength of the electromagnetic radiation propagating in the waveguide. In the absence of an applied voltage, incident electromagnetic radiation is transmitted through the waveguide, but a finite applied voltage creates a periodic change in the effective refractive index, forming a photonic band gap that reflects the incident electromagnetic radiation with high efficiency (Bragg reflection). Such fast, non-absorbing optical switches may find applications in photonic integrated circuits and optical computers. An elaboration of this basic photonic device includes a "chirped" spatial variation of the capacitance along the length of the waveguide, resulting in a broadband, voltage-dependent reflection.

[0039] Capacitive control of the polarization field of ferroelectric nematic materials can also be used to fine-tune electronic electro-optic modulators based on Mach-Zehnder interferometers containing ferroelectric nematic materials in devices that exploit the second-order nonlinear optical susceptibility of ferroelectric nematics.

[0040] According to a further embodiment, there is provided a method of controlling molecular orientation of ferroelectric nematic liquid crystal within a volume containing said liquid crystal by forming charge on and / or altering charge on one or more surfaces at least partially bounding said volume, thereby forming polarization charges within the volume and proximate to the one or more surfaces. Such a method may be utilized in the operation of devices, sensors, actuators, etc.

[0041] The exemplary embodiments of the present disclosure described above are merely illustrative of the embodiments of the present invention as defined by the appended claims and their legal equivalents, and therefore do not limit the scope of the present invention. Any equivalent embodiments are intended to be within the scope of the present invention. In addition to those shown and described herein, various modifications of the present disclosure, such as alternative useful combinations of the described elements, may become apparent to those skilled in the art from this specification. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. a volume containing a ferroelectric nematic liquid crystal material; a dielectric layer covering a portion of the volume; and a charge-carrying substrate covering at least a portion of the dielectric layer; wherein the volume comprises polarization charges on and / or adjacent to a dielectric layer that are controllable by charges applied to said charge carrying substrate.

2. The device of claim 1 , further comprising one or more additional dielectric layers covering the volume.

3. The device of claim 2 further comprising one or more additional charge carrying substrates overlying one or more additional dielectric layers.

4. 10. The device of claim 1, wherein each surface bounding the ferroelectric nematic liquid crystal includes a dielectric layer adjacent the liquid crystal and an adjacent charge-carrying substrate, and each surface has a finite capacitance and is therefore a capacitor.

5. 5. The device of claim 4, wherein the polarization charge and molecular orientation of the ferroelectric nematic liquid crystal on the inner (liquid crystal) side of the capacitor is controlled by varying the charge on the outer (substrate) side of the capacitor.

6. The device of claim 1 , wherein the dielectric layer comprises a crystalline solid, a glassy solid, a fluid, a polymer, a gel, an emulsion, a surfactant, or a liquid crystal.

7. The device of claim 1 , wherein the dielectric layer comprises an insulator.

8. The device of claim 1 , wherein the dielectric layer has finite conductivity.

9. The device of claim 1 , wherein the dielectric layer comprises a semiconductor, a self-assembled monolayer, an insulating oxide layer, a photoconductor, or a semiconductor depletion layer.

10. 10. The device of claim 1, wherein the dielectric layer comprises a surface layer of ferroelectric nematic liquid crystal, the ferroelectric polarization being fixed in the ferroelectric nematic liquid crystal.

11. 10. The device of claim 1, wherein the dielectric layer includes an alignment layer that orients ferroelectric nematic molecules near the surface.

12. The device of claim 1 , wherein the substrate comprises a crystalline solid, a glassy solid, a fluid, a polymer, a gel, an emulsion, a surfactant, or a liquid crystal.

13. The device of claim 1 , wherein the substrate comprises a conductive material.

14. The device of claim 1 , wherein the substrate comprises a semiconductor.

15. The device of claim 1 , wherein the substrate comprises an insulator.

16. The device of claim 1 , wherein the substrate comprises an electrolyte or an ionic liquid.

17. 10. The device of claim 1, wherein the charge on the interface of the ferroelectric nematic liquid crystal material and the resulting molecular orientation respond to external fields or other stimuli, including external electromagnetic or optical fields, chemical or electrochemical reactions, biomolecular binding events, mechanical strain or shear, fluid flow, or a combination thereof.

18. 18. The device of claim 17, wherein the response to an external field or other stimulus is detected electrically or optically.

19. 10. The device of claim 1, wherein a volume containing ferroelectric nematic liquid crystal material is at least partially bounded by a surface having a spatially varying capacitance, and wherein the molecular orientation of the ferroelectric nematic liquid crystal material exhibits a spatially varying analog response to an applied voltage.

20. 10. The device of claim 1, wherein a volume containing ferroelectric nematic liquid crystal material is at least partially bounded by a surface having a spatially varying capacitance and has patterned electrodes on a bounding substrate, and wherein the molecular orientation in the ferroelectric nematic liquid crystal material exhibits a spatially varying analog response to a voltage applied to the patterned electrodes.

21. 10. A system comprising the device of claim 1, wherein the system is an electro-optic, photonic or nonlinear optical device, a sensor, an actuator, a ferroelectric memory device, a bi-functional information storage and processing device, or a combination thereof.

22. The system described in claim 21, wherein the ferroelectric memory device includes an insulating dielectric layer that enables long-term retention of the molecular orientation state of the ferroelectric nematic liquid crystal under open-circuit conditions.

23. A method of controlling the molecular orientation of ferroelectric nematic liquid crystal material within a volume containing said material by forming and / or altering charge on one or more surfaces at least partially bounding said volume, thereby forming polarization charges within said volume and adjacent to said one or more surfaces.

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