Liquid crystal dimming device

Abstract

The present application relates to a liquid crystal dimming device, comprising a substrate coated with a transparent conductive layer and a liquid crystal composition with a dichroic dye added thereto sandwiched between the substrates; the resulting liquid crystal dimming device can have at least two stable states that remain basically stable after the voltage is removed, at least one of which is that the arrangement of liquid crystal molecules is basically orderly, and at least one is that the arrangement of liquid crystal molecules is multi-domain and disordered; an external voltage is applied so that the arrangement of liquid crystal molecules can be quickly switched between the above-mentioned stable states, and a liquid crystal molecule arrangement different from the stable state can also be obtained; the above-mentioned liquid crystal dimming device can adjust the incident light between a highly clear and transparent minimum absorption and minimum scattering state to a privacy state of maximum absorption and maximum scattering state, while realizing zero power consumption privacy protection and zero power consumption clear and transparent states, obtaining excellent solar radiation energy regulation and energy-saving intelligent dimming glass that can quickly switch between high-definition transparent and privacy protection states.

Description

Technical Field

[0001] The present application relates to the field of liquid crystal optoelectronic devices, and in particular to a dimming device that simultaneously realizes privacy protection and has a large dynamic range and an adjustable spectrum range. The present application particularly emphasizes the application of liquid crystal dimming devices in building materials. Background Art

[0002] Glass and glass doors and windows are one of the earliest technologies invented and commercialized by modern humans. The large-scale use of glass allows people to clearly observe the outdoor scenes and collect sunlight even when the indoor and outdoor are physically separated. However, the use of glass curtain walls and glass doors and windows also brings the disadvantages of loss of privacy and increased energy consumption.

[0003] Traditional solutions to privacy and partial solutions to increased energy consumption include mechanical devices such as curtains and blinds. Other solutions to increased energy consumption in recent years include insulating glass, Low E coating and other product technologies. In recent decades, people have conducted a lot of research on so-called dimming glass that can directly adjust the spread of light, and its product technology is becoming more and more mature. The application of dimming glass in the fields of architecture and transportation is becoming more and more extensive.

[0004] Existing dimming technologies mainly include electrochromic, suspended particle technology, and liquid crystal dimming technology. Electrochromic technology (EC) has excellent characteristics of solid-state devices, but for a product of a typical glass door and window size, its color change speed is several minutes or even tens of minutes. The lowest light transmittance or coloring state cannot play a role in privacy protection for indoor scenes when the ambient light is relatively dark. The strict device uniformity and purity requirements lead to low product yield and shortened product life. The suspended particle (SPD) technology is currently in a highly colored state when the power is off, but similar to electrochromic glass, it still does not play a role in privacy protection. At the same time, SPD technology is in a light-shielding state when the power is off, and it does not meet the requirements of turning off the power to a safe transparent state. In addition, since only a few companies have developed SPD dimming technology, its production cost is high and the technological industrialization is slow.

[0005] Liquid crystal dimming technology has made great progress due to the comprehensive industrialization of flat panel display technology. Conventional polymer dispersed liquid crystal (PDLC) has excellent privacy protection characteristics, and its products are widely used in interior decoration, interior partitions and other fields. However, including trans-PDLC technology, due to its limited viewing angle range, lack of clarity in the transparent state, and almost no regulation of solar radiation energy, it is blocked from market applications by glass doors and windows facing the exterior wall and glass curtain walls. In recent years, new dimming technologies, bistable liquid crystal dimming devices have made great improvements over PDLC technology, making it possible to be used for exterior wall glass. However, similar to PDLC technology, bistable liquid crystal dimming glass has little regulation of solar radiation energy. Dye liquid crystal dimming technology uses the characteristics of its molecular dichroic absorption. A single dye liquid crystal device only plays a regulating role for one polarized light, resulting in the need for two dye liquid crystals with perpendicular polarization directions, or a polarizer plus a dye liquid crystal device to deeply adjust natural light. Therefore, the dynamic range of dimming of a single dye liquid crystal device is narrower than that of EC and SPD technologies, the dynamic adjustment range of solar radiation energy is also smaller, and the cost is even higher. At the same time, dye liquid crystal dimming glass is similar to EC and SPD dimming technologies, and cannot play a role in protecting privacy for indoor scenes at night when the ambient light is relatively dark. In addition, it is disclosed in the published patents that the brightness adjustment device is combined with the haze adjustment device, and an independent drive connector is connected externally, so that haze and brightness adjustment can be achieved simultaneously in one device, but the double-box device process is complex and relatively heavy.

[0006] Therefore, there is a need for a dimming device that can simultaneously achieve privacy protection, selectively adjust visible light and near-infrared light over a large dynamic range, clearly visible at all viewing angles in a transparent state, able to recover to a transparent and safe state when power is off, has a fast switching speed, and has a low production cost, especially a dimming device that can be used for architectural glass. Summary of the invention

[0007] The present invention provides a novel liquid crystal dimming device, which meets the above-mentioned needs through a combination of liquid crystal material, device structure, and driving mode.

[0008] To achieve the above-mentioned purpose, the present application provides a liquid crystal dimming device, the core of which is a liquid crystal layer, the liquid crystal layer includes liquid crystal material and dichroic dyes whose molecular arrangement direction is basically consistent with that of surrounding liquid crystal molecules, the liquid crystal molecules and dichroic dye molecules have a variety of molecular arrangements under the action of intrinsic elastic force, surface force and external voltage, including an arrangement with basically consistent directions under an external voltage, at least one regular arrangement and an irregular, multi-domain molecular arrangement that are still stable in the absence of an external voltage. When the incident light passes through the liquid crystal layer with a basically regular molecular arrangement, the incident light passes through without scattering, and when the incident light passes through the liquid crystal layer with a basically irregular molecular arrangement, the incident light passes through the liquid crystal layer with increased scattering and absorption.

[0009] The following describes and illustrates the embodiments of the present invention and its purpose by means of examples and in combination with systems, tools and methods. These examples are exemplary and illustrative only, not restrictive. In various embodiments, one or more of the above market needs have been met by the present invention, while other embodiments are directed to other improvements.

[0010] The main purpose of the present invention is to provide a liquid crystal dimming device, which has at least two states that remain stable after the external voltage is removed, wherein in at least one state, the liquid crystal molecules are arranged in a basically orderly manner, and the incident light incident thereon passes through with basically no scattering or a small amount of scattering; and in at least one state, the liquid crystal molecules are arranged in a multi-domain disordered state, and the incident light incident thereon passes through after being largely absorbed and scattered.

[0011] Another object of the present invention is to provide a liquid crystal dimming device. In addition to the at least two stable states that exist after the external voltage is removed, when the external voltage is applied, the liquid crystal molecules are basically arranged in an orderly manner, and the incident light incident thereon passes through with minimal absorption and basically no scattering.

[0012] Another object of the present invention is to provide a liquid crystal dimming device, wherein at least two states of the dimming device include at least one state in which the molecular arrangement is basically ordered and at least one state in which the molecular arrangement is multi-domain disordered, and the device has a basically consistent regulating effect on mutually perpendicular linear polarized light incident thereon.

[0013] Another object of the present invention is to provide a liquid crystal dimming device, the colors of at least two stable states of the dimming device can be adjusted.

[0014] Another object of the present invention is to provide a liquid crystal dimming device, at least two stable states of which are adjustable for near-infrared light.

[0015] Another object of the present invention is to provide a liquid crystal dimming device, wherein at least two stable states and a transmission state when an external voltage is applied to the dimming device can be controlled in different areas and independently.

[0016] Another object of the present invention is to provide a driving method, which can realize the functions demonstrated by the liquid crystal dimming device provided in the present invention.

[0017] Another object of the present invention is to provide a method for assembling sheets, by which the liquid crystal dimming device provided in the present invention can be strengthened so that it can be widely used in the field of architecture.

[0018] A further object of the present invention is to provide a glass window that has the function of blocking heat exchange caused by conduction and convection, while allowing an operator to control the transparency of the glass window, the transmittance of solar radiation energy, and the privacy protection of the glass window.

[0019] According to the purpose of the present invention, the present invention provides a liquid crystal dimming device, comprising a first transparent conductive substrate, a second transparent conductive substrate, and a liquid crystal layer arranged between the first transparent conductive substrate and the second transparent conductive substrate, wherein the first transparent conductive substrate comprises a first transparent substrate and a first transparent conductive layer arranged adjacent to the liquid crystal layer, the second transparent conductive substrate comprises a second transparent substrate and a second transparent conductive layer arranged adjacent to the liquid crystal layer, the liquid crystal layer comprises a liquid crystal composition and a dichroic dye, the liquid crystal composition comprises a nematic liquid crystal composition, a chiral compound, and a bi-mesogenic compound; the liquid crystal layer is subjected to the first transparent conductive substrate. The voltage applied between the conductive substrate and the second transparent conductive substrate changes the arrangement state of the liquid crystal molecules and the corresponding dichroic dye molecules in the liquid crystal layer. The change in the arrangement of the liquid crystal molecules and the dichroic dye molecules in the liquid crystal layer causes a change in the propagation characteristics of the light incident on the liquid crystal layer, including transmission, scattering, absorption, reflection, etc. The arrangement state of the liquid crystal molecules has at least two stable states that remain basically stable after the voltage is removed, at least one of the stable states is a transmission state, which transmits the light incident on the liquid crystal layer, and at least one of the stable states is a shielding state, which can simultaneously absorb and scatter the light incident on the liquid crystal layer.

[0020] Furthermore, the nematic liquid crystal composition is a liquid crystal compound or a liquid crystal mixture having a nematic phase, and the nematic liquid crystal composition accounts for 30 wt % to 90 wt % of the liquid crystal composition.

[0021] Furthermore, the chiral compound is a chiral liquid crystal material, and the chiral compound accounts for 0.01 wt%-30 wt% of the liquid crystal composition.

[0022] Further, the bimesogenic compound is a liquid crystal compound containing two mesogenic units in the molecule, and has a structure of R1-MG1-X-MG2-R2, wherein R1 and R2 each independently represent -H, -F, -Cl or a chain alkyl group with 1 to 25 carbon atoms, wherein one or more H atoms in the chain alkyl group with 1 to 25 carbon atoms can be independently substituted by halogen, and one or more non-adjacent -CH2- in the chain alkyl group with 1 to 25 carbon atoms can be independently substituted by -O-, -CH=CH-, -CH= CF- or -CF=CF- is substituted; MG1 and MG2 each independently represent a mesogen; X is a straight-chain or branched alkylene group having 3-40 C atoms, wherein one or more -CH2- in the straight-chain or branched alkylene group having 3-40 C atoms can be independently replaced by -O-, -CH(F)-, -CH(Cl)- or -CH=CH-, and the replacement does not include two -O- adjacent to each other or two double bonds adjacent to each other; the bimesogenic compound accounts for 10wt%-50wt% of the liquid crystal composition.

[0023] Furthermore, the dichroic dye is mutually soluble in the liquid crystal composition, the dichroic dye is affected by the arrangement of liquid crystal molecules to form a certain ordered arrangement, and the order parameter of the dichroic dye is between 0.1-1; the dichroic dye accounts for 0.01wt%-5wt% of the liquid crystal composition.

[0024] Furthermore, the dichroic dye is a single component, and the absorption peak of the dichroic dye is in any wavelength band between 300nm and 2500nm.

[0025] Furthermore, the dichroic dye is a mixture of multiple components, the absorption peak of each component is in any wavelength band between 300nm-2500nm, and the absorption peaks of the components do not overlap.

[0026] Furthermore, the first transparent substrate and the second transparent substrate are flat glass, tempered glass, semi-tempered glass, float glass, or plastic substrate film.

[0027] Furthermore, the plastic substrate film is selected from at least one of PET film, PI film, PTFE film, PP film, PC film, PVC film, PE film, PS film, PA film, PEN film, PMMA film and PBT film.

[0028] Furthermore, the material of the first transparent conductive layer and the second transparent conductive layer is any one of a metal oxide film, a metal nanowire conductive film, a metal grid, and a carbon-based conductive film.

[0029] Furthermore, at least one of the first and second transparent conductive layers is composed of at least one conductive region to which a voltage can be applied independently.

[0030] Furthermore, it also includes a first alignment layer and / or a second alignment layer disposed on a side of the first transparent conductive base layer and / or the second transparent conductive base layer adjacent to the liquid crystal layer.

[0031] Furthermore, the material of the first alignment layer and / or the second alignment layer is any one of polyimide, polyvinyl alcohol, polyester, epoxy resin, polyurethane, polysilane, polystyrene and derivatives thereof.

[0032] Furthermore, the first alignment layer and / or the second alignment layer is aligned in any one of a rubbing alignment method, a photo-controlled alignment method, an oblique evaporation method, and an LB film method.

[0033] Furthermore, the alignment type of the first alignment layer and / or the second alignment layer is any one of IPS, TN, STN or VA.

[0034] Further, the alignment application operation of the first alignment layer and / or the second alignment layer is any one of a spin coating method, a dipping method, a relief printing method, a spray coating method or a slit coating method.

[0035] Furthermore, a spacer material is provided between the first transparent conductive base layer and the second transparent conductive base layer, and the spacer material is selected from at least one of resin, glass fiber and inorganic material, and the shape of the spacer material can be spherical, rod-shaped or mixed.

[0036] Furthermore, the thickness of the liquid crystal layer is 1-60 μm.

[0037] Furthermore, the thickness of the liquid crystal layer is 5-50 μm.

[0038] Furthermore, the liquid crystal dimming device can be in at least three states for visible light and near-infrared light incident thereon: a high-transmittance, low-haze state, a low-coloration, low-haze state, and a high-coloration, high-haze state.

[0039] Furthermore, the high-transmittance, low-haze state is obtained by continuously applying a first voltage between the first transparent conductive layer and the second transparent conductive layer, and at this time, the liquid crystal molecules in the liquid crystal layer in the dimming device are arranged approximately perpendicular to the first transparent conductive layer and the second transparent conductive layer; the low-coloring, low-haze state is obtained by applying a second voltage between the first transparent conductive layer and the second transparent conductive layer, and at this time, the liquid crystal molecules in the liquid crystal layer in the dimming device are approximately parallel to the first transparent conductive layer and the second transparent conductive layer and have a certain spiral structure arrangement; the high-coloring, high-haze state is obtained by applying a third voltage between the first transparent conductive layer and the second transparent conductive layer, and at this time, the liquid crystal molecules in the liquid crystal layer in the dimming device are arranged in a random focal conic state.

[0040] Furthermore, the first voltage is a continuous voltage, and the second voltage and the third voltage are pulse voltages.

[0041] Furthermore, the first voltage is an alternating voltage, the amplitude of the alternating voltage is 10-500V; the frequency of the alternating voltage is 20-10000Hz.

[0042] Furthermore, the second voltage is an alternating pulse voltage, which consists of a continuous pulse or multiple different or identical pulses, and the amplitude of the alternating pulse voltage is 10-300V; the frequency of the second voltage is 20-10000Hz; and the pulse width of the second voltage is 0.01-300s.

[0043] Furthermore, the third voltage is an alternating pulse voltage, which consists of a continuous pulse or multiple different or identical pulses, and the amplitude of the alternating pulse voltage is 10-300V; the frequency of the third voltage is 20-10000Hz; and the pulse width of the third voltage is 0.01-300s.

[0044] Further, the continuous voltage includes a gradient voltage combined with a pulse voltage.

[0045] Furthermore, the pulse voltage amplitude, frequency, and pulse width are the same as or different from the second voltage and the third voltage.

[0046] Furthermore, the light transmittance of the high-clearance, low-haze state is not less than 30%, and the haze is not higher than 5%; the light transmittance of the low-coloring, low-haze state is not higher than 50%, and the haze is not higher than 10%; the light transmittance of the high-coloring, high-haze state is not higher than 40%, and the haze is not lower than 60%.

[0047] Furthermore, the transmittance of the high-clearance, low-haze state and the low-coloration, low-haze state can be adjusted according to the composition and concentration of the added dichroic dye, and the transmittance ratio between the high-clearance, low-haze state and the low-coloration, low-haze state for incident light of a specific wavelength or wavelength range can be greater than 2:1.

[0048] To achieve the above objectives, the present application also provides a laminated liquid crystal dimming device obtained by using the above liquid crystal dimming device, comprising a first substrate, a first bonding layer, a liquid crystal dimming device, a second bonding layer and a second substrate arranged in sequence.

[0049] Furthermore, the first adhesive layer and the second adhesive layer are polymerizable high molecular compound layers with adhesive properties, and the high molecular compound layers are selected from any one or more of PVB, EVA, and SPU.

[0050] Furthermore, the first substrate and the second substrate are made of the same or different materials.

[0051] Furthermore, the materials of the first substrate and the second substrate are selected from one or more of glass, tempered glass, Low-e glass, special glass capable of blocking electromagnetic radiation, and plastic substrates.

[0052] To achieve the above-mentioned objectives, the present application also provides a hollow liquid crystal dimming device obtained by using the above-mentioned liquid crystal dimming device, comprising a first substrate, a liquid crystal dimming device and a second substrate arranged in sequence, and also comprising a hollow cavity located between the first substrate and the liquid crystal dimming device and / or between the liquid crystal dimming device and the second substrate.

[0053] Furthermore, the hollow cavity is a vacuum.

[0054] Furthermore, the hollow cavity is filled with any one or more of air, inert gas, aerogel or liquid.

[0055] Furthermore, a hollow spacer material is arranged in the hollow cavity.

[0056] Furthermore, the hollow spacer material is any one or more of strip, sheet, column, and spherical spacer materials made of polymer, metal, or non-metal.

[0057] Furthermore, the hollow spacer material is bonded and fixed by an adhesive, and the adhesive is a polymerizable high molecular compound having bonding properties to glass and plastic substrates, and the high molecular compound is any one of PVB, EVA, and SPU.

[0058] The beneficial effect of the present application is that the present application provides a liquid crystal dimming device, which realizes the functions of privacy protection and brightness adjustment in a single-box dimming device by adding a dichroic dye to a liquid crystal composition after component optimization, and the dimming device has at least two states that remain stable after the voltage is withdrawn, and only requires pulse voltage switching, without voltage maintenance, and has low power consumption; in addition, the transmittance contrast of the light and dark states of the dimming device provided by the present application can be better than the transmittance contrast of a conventional dye liquid crystal single box. At the same time, compared with conventional dye liquid crystals, it has better energy-saving effects, thereby improving the value of liquid crystal dimming devices in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a schematic diagram of the structure of the liquid crystal dimming device in this application;

[0060] Figure 2 A schematic diagram of the working principle of a liquid crystal dimming device in some embodiments of the present application;

[0061] Figure 3 A schematic diagram of a driving method of a liquid crystal dimming device in the present application;

[0062] Figure 4 This is a UV-visible-near-infrared transmission spectrum of the liquid crystal dimming device in Example 1 using collimated light;

[0063] Figure 5 This is a UV-visible-near-infrared transmission spectrum of the liquid crystal dimming device in Example 2 using collimated light;

[0064] Figure 6 The ultraviolet, visible and near-infrared transmission spectrum of the liquid crystal dimming device in Example 1 using an integrating sphere;

[0065] Figure 7 The ultraviolet, visible and near-infrared transmission spectrum of the liquid crystal dimming device in Example 2 using an integrating sphere;

[0066] Figure 8 The liquid crystal dimming device in Example 1 is in (a) a high-clearance, low-haze state, (b) a low-coloring, low-haze state, and (c) a high-coloring, high-haze state under corresponding driving voltages;

[0067] Fig. 9 This is a schematic diagram of the structure of the laminated liquid crystal dimming device in this application;

[0068] Fig.10 This is a schematic diagram of the structure of the hollow liquid crystal dimming device in this application. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in combination with the specific embodiments and drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments, and are not used to limit the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0070] like Figure 1 As shown, the liquid crystal dimming device 100 provided in the present application includes a first transparent conductive substrate 101, a second transparent conductive substrate 102, and a liquid crystal layer 103 arranged between the first transparent conductive substrate 101 and the second transparent conductive substrate 102, the first transparent conductive substrate 101 includes a first transparent substrate 104 and a first transparent conductive layer 105 arranged adjacent to the liquid crystal layer, the second transparent conductive substrate 102 includes a second transparent substrate 106 and a second transparent conductive layer 107 arranged adjacent to the liquid crystal layer, as a preferred embodiment, at least one of the first transparent conductive layer 105 and the second transparent conductive layer 107 is composed of at least one conductive region to which a voltage can be applied independently; as a preferred embodiment, the liquid crystal layer 103 The thickness is 1-60 μm. As a further preferred embodiment, the thickness of the liquid crystal layer 103 is 5-50 μm. The liquid crystal layer includes a liquid crystal composition and a dichroic dye, and the liquid crystal composition includes a nematic liquid crystal composition, a chiral compound and a bimesogenic compound. The liquid crystal layer is subjected to a voltage applied between the first transparent conductive substrate 101 and the second transparent conductive substrate 102 to change the arrangement state of the liquid crystal molecules in the liquid crystal layer. There are at least two stable states in the arrangement state of the liquid crystal molecules that remain basically stable after the voltage is removed, at least one of the stable states is a transmission state, and the transmission state is transparent for light incident on the liquid crystal layer, and at least one of the stable states is a shielding state, and the shielding state can simultaneously absorb and scatter the light incident on the liquid crystal layer.

[0071] The working principle of the liquid crystal dimming device of the present application is as follows Figure 2 As shown, arrow 203 indicates the path of light; wherein, due to the interaction between the interface and the elastic force of the liquid crystal, Figure 2(a) When there is no external voltage applied to the liquid crystal layer, the liquid crystal molecules 201 are arranged roughly parallel to the upper and lower substrates, and the dichroic dye molecules 202 are miscible in the liquid crystal and arranged with the liquid crystal molecules 201. At this time, the liquid crystal molecules and dye molecules are arranged in a basically orderly manner, forming a basically uniform planar molecular arrangement with a spiral structure. When the incident light is incident on the liquid crystal layer, the light modulation ability of the liquid crystal layer depends on the order of the arrangement of the liquid crystal and dye molecules, the concentration of the dye molecules, and the helical pitch value. The liquid crystal layer absorbs polarized light whose polarization rotation direction is basically consistent with the direction of the liquid crystal spiral structure more than the polarized light rotating in the opposite direction. Therefore, the transmitted light has a certain rotational polarization characteristic. Generally, the transmitted light generally has a certain polarization characteristic. At the same time, because the liquid crystal molecules are arranged in a basically orderly manner, the liquid crystal layer has a low scattering of the light incident thereon, so that the liquid crystal dimming device presents a low coloring and low haze state dominated by light absorption and transmission;

[0072] pass Figure 2 The first transparent conductive substrate 101 and the second transparent conductive substrate 102 can apply any voltage to the liquid crystal layer. The voltage parameters depend on the initial arrangement of the liquid crystal molecules, the dielectric anisotropy and the elastic force between them. When the external electric field is large enough, the liquid crystal molecules 201 can be arranged in a direction roughly parallel to the direction of the external electric field, forming a Figure 2 (c) The liquid crystal molecules 201 and the dichroic dye molecules 202 arranged with the liquid crystal molecules 201 are arranged roughly perpendicular to the upper and lower substrates. At this time, the liquid crystal and dye molecules are arranged in a relatively highly ordered manner, and the liquid crystal layer has extremely low absorption and extremely low scattering of the light incident thereon, so that the liquid crystal dimming device presents a high-transmittance and low-haze state with light transmission as the main feature;

[0073] Within a certain range, due to the relatively strong torque and elasticity of the liquid crystal molecules, the application of an external electric field can cause the liquid crystal layer to form multiple disordered molecular domains 204. In each molecular domain 204, the liquid crystal molecules still have a basically ordered spiral arrangement, while the orientations between the molecular domains 204 are basically disordered, such as Figure 2 (b) As shown in the liquid crystal layer. After the external electric field is removed from the liquid crystal layer, the molecular arrangement in this multi-domain disordered state can be maintained for a long time, forming a stable liquid crystal molecular arrangement. When incident light is incident on the liquid crystal layer, the multi-domain structure of the liquid crystal molecules can strongly scatter the incident light. At the same time, the multi-domain structure of the liquid crystal molecules, especially the disordered arrangement of the dichroic dyes, can fully absorb the incident light, so that the liquid crystal layer forms a relatively high absorption and scattering of the incident light as a whole, which is basically unrelated to the polarization direction, so that the liquid crystal dimming device presents a high coloration and high haze state dominated by light absorption and light scattering.

[0074] According to the working principle of the liquid crystal dimming device provided in the present application, when the external voltage V applied to the liquid crystal layer 103 through the first transparent conductive layer 105 and the second transparent conductive layer 107 changes, the specific arrangement of the liquid crystal molecules and their switching speed will change, and at the same time, the light transmission, absorption, and scattering state incident on the liquid crystal layer and the response speed of the dimming device will change. In addition, when the pulse width of the external voltage changes, especially the application of continuous voltage, the arrangement of the liquid crystal molecules can be gradually ordered, forming a dimming device with different transmitted light flux and scattered light flux.

[0075] The present application provides a driving method for a liquid crystal dimming device, wherein the driving method comprises: Figure 3 The external voltage V shown is realized. The external voltage is a continuous alternating voltage such as Figure 3 (a) or Figure 3 (b) The dimming device of the present application has no limitation on the waveform of the alternating voltage used for driving, and any one or more of sine wave, trapezoidal wave, step wave, square wave, triangle wave and sawtooth wave can be selected.

[0076] According to the above working principle and driving method, the present application provides a driving method for obtaining high-definition transparency and low-haze state. Figure 2 (a) shows a low coloration, low haze state and Figure 2 (b) shows a highly colored, high haze state, and the first transparent conductive layer 105 and the second transparent conductive layer 107 are applied to the liquid crystal layer 103 as shown in FIG. Figure 3 The alternating voltage with a high enough amplitude (a) causes the molecular arrangement of the liquid crystal layer to be converted into Figure 2 (c) shows a vertically ordered molecular arrangement state, so that the liquid crystal dimming device of the present application can achieve a high-definition transparency and low-fog state. Figure 3 As the applied voltage shown in (a) continues to be applied, the molecules in the liquid crystal layer are arranged vertically and orderly. Figure 2 (c) shows the molecular arrangement state, and the dimming device is in a state of high transparency and low haze.

[0077] According to the above working principle and driving method, the present application provides a driving method for obtaining a low coloring and low haze state. Figure 3 (b) The applied pulse width t1 of voltage V1 is high enough to cause it to briefly enter a highly vertically ordered arrangement. Figure 2 (c) shows the molecular arrangement state. The liquid crystal layer 103 will experience a short relaxation from the high-transparency and low-haze state and return to the state where the molecules of the liquid crystal layer are basically ordered under the surface force and the elastic force between the liquid crystal molecules. Figure 2(a) shows the planar state, the dimming device is in a low-color and low-haze state. This state can remain stable for a long time after the external voltage is removed. The relaxation process of the liquid crystal and dye molecules from the vertical state to the planar state depends on the elastic properties of the liquid crystal material. When the elastic constant K of the liquid crystal material 33 ≈K 22 When the light is turned on, the liquid crystal and dye molecules can quickly recover from the vertical state to the planar state, achieving a perfect planar state with extremely small haze.

[0078] According to the above working principle and driving method, the present application provides a driving method for obtaining a high coloration and high haze state. When the dimming device is in a low coloration and low haze planar state, the first transparent conductive layer 105 and the second transparent conductive layer 107 are applied to the liquid crystal layer 103. Figure 3 (b) When the voltage V2 of the applied pulse width t2 is applied to the liquid crystal layer 103 through the first transparent conductive layer 105 and the second transparent conductive layer 107, or when the dimming device is in a multi-domain opaque state with high coloration and high haze, Figure 3 The applied pulse voltage series shown in (c) causes the liquid crystal dimming device to first enter the low coloration and low haze state at t2, thereby causing the liquid crystal layer to quickly transform from a basically ordered state to a Figure 2 (b) shows a multi-domain disordered molecular arrangement state, so that the liquid crystal dimming device of the present application reaches a high coloring and high haze state, and can still maintain a stable high coloring and high haze state after the power is turned off after the pulse.

[0079] The liquid crystal composition of the present application belongs to a guest-host cholesteric liquid crystal composition. The so-called guest-host cholesteric liquid crystal composition takes cholesteric liquid crystal as a host, and adds a dichroic dye as a guest to form a GH-type cholesteric liquid crystal material. In the guest-host mode, the arrangement state of the liquid crystal molecules is changed by applying different voltages, showing the optical properties of the cholesteric liquid crystal. At the same time, the dichroic dye molecules will also be oriented with the orientation of the liquid crystal, showing the absorption anisotropy of the dichroic dye molecules.

[0080] The guest-host cholesteric liquid crystal composition used in the present application includes a nematic liquid crystal composition, a chiral compound and a bimesogenic compound; as a preferred embodiment, the nematic liquid crystal is a liquid crystal compound or a liquid crystal mixture having a nematic phase, and the nematic liquid crystal composition accounts for 30wt%-90wt% of the liquid crystal composition. Among them, the nematic liquid crystal composition is mainly used to provide basic liquid crystal parameters, such as phase transition point, refractive index anisotropy and dielectric anisotropy, and the chiral compound added to the nematic liquid crystal composition can form a cholesteric liquid crystal.

[0081] As a preferred embodiment, the chiral compound is a chiral liquid crystal material, and the chiral compound accounts for 0.01wt%-30wt% of the liquid crystal composition; the chiral compound can adjust the helical pitch P of the cholesteric liquid crystal, as shown by the formula P=1 / (HTP*c), wherein the HTP value is the helical twist constant, and c is the concentration of the chiral compound. The helical pitch P can be adjusted by selecting chiral compounds with different HTP values ​​or adjusting the concentration of the chiral compound; the helical pitch P affects the planar Bragg reflection band. According to the solar energy spectrum, in order to obtain a higher solar heat gain coefficient difference between the planar state and the vertical state, the Bragg reflection band is generally adjusted to the visible near-infrared region where the solar radiation energy is stronger; the helical pitch P also affects the haze, and a certain d / P value (d is the thickness of the liquid crystal layer) needs to be controlled to obtain a higher haze haze. However, for general chiral nematic liquid crystals, a high d / P value is prone to cause planar defects, resulting in a higher and uneven planar haze. The addition of a bi-mesogenic compound can effectively solve this problem.

[0082] The bi-mesogenic compound is an elastic constant regulator. After adding chiral nematic liquid crystal, a relatively high splay elastic constant K can be obtained. 11 , relatively low bending elastic constant K 33 and a relatively low flexural modulus K 22 , the driving voltage of the liquid crystal molecules from any state to the vertical state is related to K 22 The square root is proportional to the 22 A relatively low vertical state driving voltage can be obtained. In addition, when the liquid crystal molecules recover from the vertical state to the planar state, the helical pitch changes from infinity to a natural helical pitch, at which time P′=K 33 / K 22 *P, when K 33 ≈K 22 When the liquid crystal molecules are turned on, they can quickly recover from the vertical state to the planar state, achieving a perfect planar state with minimal haze.

[0083] As a preferred embodiment, the bimesogenic compound is a liquid crystal compound containing two mesogenic units in the molecule, and the structure is R1-MG1-X-MG2-R2;

[0084] Wherein, R1 and R2 each independently represent -H, -F, -Cl or a chain alkyl group with 1-25 carbon atoms. As a further preferred embodiment, one or more H atoms in the chain alkyl group with 1-25 carbon atoms can be independently replaced by halogen, and one or more non-adjacent -CH2- in the chain alkyl group with 1-25 carbon atoms can be independently replaced by -O-, -CH=CH-, -CH=CF- or -CF=CF-; MG1 and MG2 each independently represent a mesogen; X is a straight or branched alkylene group with 3-40 carbon atoms. As a further preferred embodiment, one or more -CH2- in the straight or branched alkylene group with 3-40 carbon atoms can be independently replaced by -O-, -CH(F)-, -CH(Cl)- or -CH=CH-, and the replacement does not include two -O- adjacent to each other or two double bonds adjacent to each other; the bimesogenic compound accounts for 10wt%-50wt% of the liquid crystal composition.

[0085] The liquid crystal layer of the present application also includes a dichroic dye. As a preferred embodiment, the dichroic dye is mutually soluble in the liquid crystal composition. The dichroic dye is affected by the arrangement of liquid crystal molecules to form a certain ordered arrangement. The order parameter of the dichroic dye is between 0.1 and 1. The dichroic dye accounts for 0.01wt%-5wt% of the liquid crystal composition.

[0086] Dichroic dyes can be selected and used as conventional dyes that are known to be oriented according to the orientation state of liquid crystal compounds due to the so-called guest-host effect, and this application does not make specific restrictions; the dichroic dyes are represented by order parameters according to the orientation characteristics of liquid crystal compounds. The order parameters of dichroic dyes are related to the structure of the dye itself and the properties of the main liquid crystal; generally speaking, the higher the order parameter of the dichroic dye, the higher the order of the liquid crystal orientation, but since the order parameter of the existing dichroic dyes is less than 1, although the liquid crystal molecules can basically be oriented with the electric field, there is always a part of the dye molecules that cannot be completely oriented with the liquid crystal molecules. This part of the dye molecules will absorb a part of the light, so in fact, there is some weak absorption even in the vertical state with high transparency. Generally speaking, the larger the order parameter, the higher the contrast between the vertical state and the planar state or the focal conic state. Therefore, in order to obtain a higher contrast, dichroic dyes with high order parameters are generally selected, and the solubility, extinction coefficient, photothermal stability and resistivity of the dichroic dye in the main liquid crystal should also be considered. In addition, the dynamic adjustment range of solar radiation is affected by the composition and content of the dichroic dye. When the composition and content of the dye are appropriate, the difference between the maximum transmittance state and the minimum transmittance state of the collimated light incident thereon can be greater than 50%; further, the difference between the maximum transmittance state and the minimum transmittance state of the collimated light incident thereon can be greater than 60%; when the dye content is high enough, the maximum transmittance of the collimated light incident thereon can be reduced to less than 30%, and the corresponding difference between the maximum transmittance state and the minimum transmittance state of the collimated light incident thereon will also be reduced.

[0087] As a preferred embodiment, the dichroic dyes are preferably two or more, more preferably three or more dichroic dyes, to perform different color settings. The types of dichroic dyes and the precise mixing methods of the dichroic dyes are known to those skilled in the art and are not particularly limited in this application.

[0088] As a preferred embodiment, the dichroic dye is a single component, and the absorption peak of the dichroic dye is in any band between 300nm-2500nm; the dichroic dye can also be a mixture composed of multiple components, and the absorption peak of each component is in any band between 300nm-2500nm, and the absorption peaks of the components do not overlap.

[0089] As a preferred embodiment, the first transparent substrate and the second transparent substrate are flat glass, tempered glass, semi-tempered glass, float glass, or a plastic substrate film; as a further preferred embodiment, the plastic substrate film is selected from at least one of PET film, PI film, PTFE film, PP film, PC film, PVC film, PE film, PS film, PA film, PEN film, PMMA film, and PBT film, but the present application is not limited thereto.

[0090] As a preferred embodiment, the material of the first transparent conductive layer and the second transparent conductive layer is any one of a metal oxide film, a metal nanowire conductive film, a metal grid, and a carbon-based conductive film. As a preferred embodiment, the liquid crystal dimming device also includes a first alignment layer and / or a second alignment layer arranged on the side of the first transparent conductive base layer and / or the second transparent conductive base layer adjacent to the liquid crystal layer; as a further preferred embodiment, the material of the first alignment layer and / or the second alignment layer is any one of polyimide, polyvinyl alcohol, polyester, epoxy resin, polyurethane, polysilane, polystyrene and their derivatives; as a further preferred embodiment, the orientation mode of the first alignment layer and / or the second alignment layer is any one of friction orientation method, light-controlled orientation method, inclined evaporation method, and LB film method; as a further preferred embodiment, the alignment type of the first alignment layer and / or the second alignment layer is any one of IPS, TN, STN or VA type; as a further preferred embodiment, the alignment operation of the first alignment layer and / or the second alignment layer is any one of spin coating, immersion, letterpress printing, spraying or slit coating, but the present application is not limited thereto.

[0091] As a preferred embodiment, a spacer material is provided between the first transparent conductive base layer and the second transparent conductive base layer, and the spacer material is selected from at least one of resin, glass fiber and inorganic material, and the shape of the spacer material can be spherical, rod-shaped or mixed.

[0092] As a preferred embodiment, the liquid crystal dimming device can be in at least three states for visible light and near-infrared light incident thereon: a high-definition transmittance and low-haze state, a low-coloration and low-haze state, and a high-coloration and high-haze state; as a further preferred embodiment, the high-definition transmittance and low-haze state is obtained by continuously applying a first voltage between the first transparent conductive layer and the second transparent conductive layer, at which time the absorption axes of the liquid crystal molecules and the dye molecules in the liquid crystal layer in the dimming device are arranged approximately perpendicular to the first transparent conductive layer and the second transparent conductive layer; the low-coloration and low-haze state is obtained by applying a second voltage between the first transparent conductive layer and the second transparent conductive layer. A voltage is applied between the first transparent conductive layer and the second transparent conductive layer to obtain a high color and high haze state. At this time, the absorption axes of the liquid crystal molecules and dye molecules in the liquid crystal layer in the dimming device are roughly parallel to the first transparent conductive layer and the second transparent conductive layer and have a certain spiral structure arrangement, which is in a planar state of absorption and transmission, satisfies the Bragg reflection characteristics, and can reflect light in the λ=nP band, where n is the average refractive index of the liquid crystal and P is the cholesteric liquid crystal spiral pitch; the high coloring and high haze state is obtained by applying a third voltage between the first transparent conductive layer and the second transparent conductive layer. At this time, the liquid crystal molecules in the liquid crystal layer in the dimming device are arranged in a random focal cone state, which is in an absorption and scattering state and has a good shielding effect.

[0093] As a further preferred embodiment, the light transmittance of the high-definition, low-haze state is not less than 30%, and the haze is not higher than 5%; the light transmittance of the low-coloring, low-haze state is not higher than 50%, and the haze is not higher than 10%; the light transmittance of the high-coloring, high-haze state is not higher than 40%, and the haze is not lower than 60%;

[0094] As a further preferred embodiment, the transmittance of the high-clearance, low-haze state and the low-coloration, low-haze state can be adjusted according to the composition and concentration of the added dichroic dye, and the transmittance ratio between the high-clearance, low-haze state and the low-coloration, low-haze state for incident light of a specific wavelength or wavelength range can be greater than 2:1.

[0095] As a preferred embodiment, the first voltage is a continuous voltage, and the second voltage and the third voltage are pulse voltages. As a further preferred embodiment, the first voltage is an alternating voltage, the amplitude of the alternating voltage is 10-500V; the frequency of the alternating voltage is 20-10000Hz; the second voltage is an alternating pulse voltage, the alternating pulse voltage consists of a continuous pulse or a plurality of different or identical pulses, the amplitude of the alternating pulse voltage is 10-300V; the frequency of the second voltage is 20-10000Hz; the pulse width of the second voltage is 0.01-300s; the third voltage is an alternating pulse voltage, the alternating pulse voltage consists of a The third voltage is composed of a continuous pulse or a plurality of different or identical pulses, the amplitude of the alternating pulse voltage is 10-300V; the frequency of the third voltage is 20-10000Hz; the pulse width of the third voltage is 0.01-300s; as a further preferred embodiment, the continuous voltage includes a gradient voltage combined with the pulse voltage to achieve the purpose of high-definition transparency and low-haze state first driven by high voltage and then maintained by low voltage, so as to reduce power consumption; as a further preferred embodiment, the amplitude, frequency and pulse width of the pulse voltage are the same as or different from the second voltage and the third voltage.

[0096] To further achieve the purpose of the present application, the present application also provides a laminated liquid crystal dimming device obtained by using the above-mentioned liquid crystal dimming device, such as Fig. 9 As shown, it includes a first substrate 901, a first adhesive layer 902, a liquid crystal dimming device 100, a second adhesive layer 903 and a second substrate 904 which are arranged in sequence.

[0097] As a preferred embodiment, the first adhesive layer 902 and the second adhesive layer 903 are polymerizable high molecular compound layers with adhesive properties, and the high molecular compound layers are selected from any one or more of PVB, EVA, and SPU, but the present application is not limited thereto.

[0098] As a preferred embodiment, the first substrate 901 and the second substrate 904 are made of the same or different materials; as a further preferred embodiment, the materials of the first substrate and the second substrate are selected from one or more of glass, tempered glass, Low-e glass, special glass that blocks electromagnetic wave radiation, and plastic substrates.

[0099] To further achieve the purpose of the present application, the present application also provides a hollow liquid crystal dimming device obtained by using the above liquid crystal dimming device, such as Fig.10 As shown, it includes a first substrate 901, a liquid crystal dimming device 100 and a second substrate 904 arranged in sequence, and also includes a hollow cavity 1001 located between the first substrate and the liquid crystal dimming device and / or between the liquid crystal dimming device and the second substrate.

[0100] As a preferred embodiment, the hollow cavity 1001 is a vacuum or is filled with any one or more of air, inert gas, aerogel or liquid; as a further preferred embodiment, a hollow spacer material 1002 is arranged in the hollow cavity; as a further preferred embodiment, the hollow spacer material adopts any one or more of strip, sheet, columnar and spherical spacer materials made of polymer, metal or non-metallic materials; as a further preferred embodiment, the hollow spacer material is bonded and fixed by an adhesive, and the adhesive is a polymer compound that can be polymerized and has bonding properties to glass and plastic substrates, and the polymer compound is any one of PVB, EVA, SPU, but the present application is not limited to this.

[0101] In the present application and especially in the following examples, the group structures in the liquid crystal composition are also coded; Table 1 shows the group structures and codes for the nematic liquid crystal composition and the bimesogenic compound;

[0102] Table 1 Liquid crystal composition group structure code

[0103]

[0104] Among them, "5PPN", according to the naming principle of Table 1, its corresponding structure is:

[0105]

[0106] "n=3", according to the naming principle in Table 1, its corresponding structure is: -C3H7.

[0107] In this application, the structural formula, corresponding code and HTP value of the chiral compound added to the liquid crystal composition are also provided, and the results are shown in Table 2.

[0108] Table 2 Structural formula, code and HTP value of chiral compounds added to liquid crystal compositions

[0109]

[0110] In the present application, the code and order parameter of the dichroic dye added to the liquid crystal composition are also provided, and the results are shown in Table 3; wherein the order parameter can be measured by the following method: the dichroic dye is mixed into the nematic liquid crystal composition in the following Preparatory Example 1, and is configured into a dye mixed crystal with a mass concentration of 1%, and is fully stirred at 120°C for 1h; after the dye mixed crystal is cooled to room temperature, it is respectively poured into two 10μm liquid crystal cells with upper and lower surfaces rubbed in an antiparallel orientation, and when the polarized light is parallel and perpendicular to the liquid crystal cell rubbing orientation, A is measured. ∥ and A ⊥ , substitute into the following formula to calculate the order parameter;

[0111]

[0112] Table 3 Codes and order parameters of dichroic dyes added to liquid crystal compositions

[0113] Code Components Ordered parameters R1 Black is mixed from three components 0.79 R2 Black is mixed from three components 0.78 R3 Dark blue mixed from two components 0.71

[0114] Examples

[0115] The present application provides 3 groups of preliminary examples and 14 groups of embodiments to demonstrate the apparatus and method of the present disclosure, which are shown in Tables 4-6 and 7, respectively; wherein preliminary examples 1-3 respectively represent nematic liquid crystal compositions of different compositions; it should be noted that the following embodiments are merely illustrative and are not intended to limit the present disclosure to the materials, conditions or process parameters described herein.

[0116] Preparatory Example 1

[0117] Table 4 Nematic liquid crystal composition formula 1

[0118] Composition code content / % 5PPN 25 2PPN 9.3 5OPPN 19 6OPPN 9.3 3PGPN 20 5CPPN 11 5PPPN 5.6

[0119] Preparatory Example 2

[0120] Table 5 Nematic liquid crystal composition formula 2

[0121] Composition code content / % 5PPN 19 2PPN 7.4 5OPPN 11 6OPPN 4.6 3PGPN 19 5CPPN 11 5PPPN 10 <![CDATA[5PGP 22 QP 22 F]]> 3.7 <![CDATA[4PGP 22 QP 22 F]]> 3.7

[0122] Preparatory Example 3

[0123] Table 6 Nematic liquid crystal composition formula 3

[0124]

[0125]

[0126] Examples 1-14

[0127] Table 7 Liquid crystal composition formula in Examples 1-14

[0128]

[0129] In order to verify that the technical solution provided in the present application has excellent technical effects, the liquid crystal compounds in each embodiment are made into corresponding liquid crystal dimming devices, and their performances are tested.

[0130] (1) Liquid crystal dimming device structure

[0131] In the liquid crystal dimming devices of Examples 1-5 and Examples 8-14, the transparent conductive base layer is ITO transparent glass, the alignment layer is VA type, and the alignment is performed by rubbing alignment method; the liquid crystal layer thickness is 20 μm, and the supporting structure is a spherical polystyrene spacer, which accounts for 0.2 wt% of the liquid crystal composition;

[0132] Different from Examples 1-5 and Examples 8-14, in the liquid crystal dimming device of Example 6, the alignment layer is of IPS type, and is oriented by up and down anti-parallel friction, and the thickness of the liquid crystal layer is 15μm; in the liquid crystal dimming device of Example 7, the alignment layer is of VA type, and the thickness of the liquid crystal layer is 10μm.

[0133] (2) Transmittance and haze evaluation

[0134] The liquid crystal dimming device was placed at a constant temperature of 25°C for more than 30 minutes, and was driven to a low coloration, low haze state and a high coloration, high haze state using a pulse voltage, and was driven to a high definition, low haze state using a continuous voltage. The transmittance and haze were then measured using a WGT-S haze meter, and the contrast was calculated. The contrast was the ratio of the maximum transmittances of the two states, i.e., D1 = T (high definition, low haze state) / T (low coloration, low haze state), D2 = T (high definition, low haze state) / T (high coloration, high haze state). The results are shown in Table 8, where T represents transmittance and H represents haze.

[0135] Table 8 Transmittance, haze and contrast of the liquid crystal dimming devices prepared in Examples 1-14

[0136]

[0137] (3) Haze stability test

[0138] The liquid crystal dimming device was placed in a constant temperature environment box at 25°C for more than 30 minutes, and appropriate voltages were selected to drive it to low coloration, low haze state and high coloration, high haze state respectively. Then, it was placed in a 25°C environment box for 16 hours. After being taken out, the transmittance and haze were measured using a WGT-S haze meter. The results are shown in Table 9.

[0139] Table 9 Transmittance and haze of the liquid crystal dimming devices prepared in Examples 1-14 after being placed for 16 hours

[0140]

[0141]

[0142] It can be seen from the data in Tables 8-9 that the dimming device of the present application can simultaneously realize brightness adjustment and haze adjustment in a single-box device, wherein the transmittance of the high-clearance, low-haze state is not less than 30%, and the haze is not higher than 5%, and ideally, the haze is not higher than 1%; the transmittance of the low-coloring, low-haze state is not higher than 50%, and the haze is not higher than 10%, and ideally, the haze is not higher than 2%; the transmittance of the high-coloring, high-haze state is not higher than 40%, and the haze is not lower than 60%, and ideally, the haze is not lower than 75%; in addition, both the low-coloring, low-haze state and the high-coloring, high-haze state are steady states, and state switching only requires a pulse voltage, with almost zero power consumption, and the state can still remain stable for a long time after the voltage is removed. Ideally, the haze change does not exceed 5% after 16 hours of placement, and more ideally, the haze change does not exceed 2% after 16 hours of placement. It has the advantages of power-off safety and good haze stability.

[0143] From the contrast shown in Table 8, it can be seen that when the liquid crystal and dye composition, dye concentration, box thickness, and interface conditions of the single-box dimming device of the present application are appropriate, the transmittance contrast between the high-transmittance, low-haze state and the low-coloring, low-haze state for incident light within a specific wavelength or wavelength range can be greater than 2, which is better than the transmittance contrast between the light and dark states of the ordinary GH-type nematic phase single-box device. This is because the addition of the chiral agent makes the planar state have a certain spiral structure. When the helical pitch is small, the number of turns of the liquid crystal molecules in the liquid crystal layer of the same thickness increases, and the multi-layer reflection is conducive to the absorption of the incident light. The transmittance of the high-coloring, high-haze state is further reduced due to the combined effects of absorption and scattering, thereby further increasing the transmittance contrast between the high-transmittance, low-haze state and the high-coloring, high-haze state for incident light within a specific wavelength or wavelength range. It can be greater than 3 under the same conditions. At the same time, it is foreseeable that a higher contrast can be achieved by increasing the order parameter of the dichroic dye.

[0144] Depend on Figure 4-5 It can be seen that the high coloring, high haze state 403 of the liquid crystal dimming device in the present application has a collimated light transmittance of ≤3% in the range of 300nm-650nm and a collimated light transmittance of ≤7% in the range of 650nm-1100nm, and has extremely low collimated light transmittance in the ultraviolet visible near infrared region. Combined with the data in Tables 8 and 9, the high coloring, high haze state 403 has high haze and haze stability, and it can be seen that the dimming device of the present application has an excellent privacy protection function; Figure 4-5It can be seen that the maximum transmittance state of the collimated light incident thereon is the high-transmittance, low-haze state 401, and the minimum transmittance state of the collimated light incident thereon is the high-coloring, high-haze state 403. The high-transmittance, low-haze state 401 of the liquid crystal dimming device in this application has a collimated light transmittance of 66%-70% at 400nm-650nm, and a collimated light transmittance of 67-82% at 650nm-1100nm. The difference between the maximum transmittance state and the minimum transmittance state for the collimated light incident thereon is greater than 50%. The ultraviolet visible near-infrared collimated light transmission spectrum of Example 3-14 has a foreseeable principle effect similar to that of Example 1 and Example 2, which will not be repeated here.

[0145] Depend on Figure 6-7 It can be seen that the liquid crystal dimming device in the present application has a dynamic adjustment range of solar radiation, that is, the high-transmittance, low-haze state 401 is mainly transparent in the whole band, the low-coloring, low-haze state 402 absorbs in the visible region and reflects in the near-infrared region. This reflection band originates from Bragg reflection and can be adjusted to the visible, near-infrared, and infrared regions in some embodiments; the high-coloring, high-haze state 403 absorbs in the visible region and diffusely reflects in the near-infrared region; compared with the ordinary GH-type nematic phase single-box device, the low-coloring, low-haze state 402 increases the wide reflection band, and compared with the cholesteric phase bistable dimming device and the PDLC haze dimming device, the low-coloring, low-haze state 402 increases the wide visible region absorption, which has a more energy-saving effect. The ultraviolet-visible near-infrared integrated transmission spectrum of Example 3-14 has a foreseeable principle effect similar to that of Example 1 and Example 2, which will not be repeated here.

[0146] Figure 8 The working effect diagram of the liquid crystal dimming device in Example 1 is shown. Figure 8 (a) shows that it is in a high-definition and low-haze state under the corresponding driving voltage. Figure 8 (b) shows that it is in a low coloration, low haze state at the corresponding driving voltage, Figure 8 (c) shows it in a high coloration, high haze state at the corresponding driving voltage.

[0147] Although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0148] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A liquid crystal dimming device, characterized in that: The invention comprises a first transparent conductive substrate, a second transparent conductive substrate and a liquid crystal layer arranged between the first transparent conductive substrate and the second transparent conductive substrate, wherein the first transparent conductive substrate comprises a first transparent substrate and a first transparent conductive layer arranged adjacent to the liquid crystal layer, the second transparent conductive substrate comprises a second transparent substrate and a second transparent conductive layer arranged adjacent to the liquid crystal layer, the liquid crystal layer comprises a liquid crystal composition and a dichroic dye, the liquid crystal composition comprises a nematic liquid crystal composition and a chiral compound; the liquid crystal layer is subjected to an applied voltage to change the arrangement state of liquid crystal molecules in the liquid crystal layer, the arrangement state of the liquid crystal molecules has at least two stable states that remain substantially stable after the voltage is removed, at least one of the stable states is a transmission state, the transmission state has a collimated transmission light flux of visible light incident on the liquid crystal layer that is greater than the scattered light flux, and at least one of the stable states is a shielding state, the shielding state has a collimated transmission light flux of visible light incident on the liquid crystal layer that is less than the collimated transmission light flux of the transmission state; The shielding state can simultaneously absorb and scatter light incident on the liquid crystal layer. In the shielding state, the liquid crystal layer forms a plurality of molecular domains with disordered orientations.

2. The liquid crystal dimming device according to claim 1, characterized in that: The nematic liquid crystal composition is a liquid crystal compound or a liquid crystal mixture having a nematic phase, and the nematic liquid crystal composition accounts for 30 wt % to 90 wt % of the liquid crystal composition.

3. The liquid crystal dimming device according to claim 1, characterized in that: The chiral compound is a chiral liquid crystal material, and the chiral compound accounts for 0.01 wt%-30 wt% of the liquid crystal composition.

4. The liquid crystal dimming device according to claim 1, characterized in that: The liquid crystal layer further includes an elastic constant adjuster.

5. The liquid crystal dimming device according to claim 4, characterized in that: The bending elastic constant K33 of the liquid crystal layer is substantially equal to the flexural elastic coefficient K22.

6. The liquid crystal dimming device according to claim 4, characterized in that: The elastic constant adjuster includes a bimesogenic compound.

7. The liquid crystal dimming device according to claim 6, characterized in that: The bimesogenic compound is a liquid crystal compound containing two mesogenic units in the molecule, and has a structure of R1-MG1-X-MG2-R2, wherein R1 and R2 each independently represent -H, -F, -Cl or a chain alkyl group with 1 to 25 carbon atoms, wherein one or more H atoms in the chain alkyl group with 1 to 25 carbon atoms can be independently replaced by halogen, and one or more non-adjacent -CH2- in the chain alkyl group with 1 to 25 carbon atoms can be independently replaced by -O-, -CH=CH-, -CH=CF- or -CF=CF-; MG1 and MG2 each independently represent a mesogen; X is a straight or branched alkylene group having 3-40 C atoms, wherein one or more -CH2- in the straight or branched alkylene group having 3-40 C atoms can be independently replaced by -O-, -CH(F)-, -CH(Cl)- or -CH=CH-, and the replacement does not include two -O- adjacent to each other or two double bonds adjacent to each other; the bimesogenic compound accounts for 10wt%-50wt% of the liquid crystal composition.

8. The liquid crystal dimming device according to claim 1, characterized in that: The dichroic dye is mutually soluble in the liquid crystal composition.

9. The liquid crystal dimming device according to claim 1, characterized in that: The dichroic dye is affected by the arrangement of liquid crystal molecules to form a certain ordered arrangement, and the order parameter of the dichroic dye is between 0.1-1.

10. The liquid crystal dimming device according to claim 1, characterized in that: The dichroic dye accounts for 0.01 wt % to 5 wt % of the liquid crystal composition.

11. The liquid crystal dimming device according to claim 1, characterized in that: The dichroic dye is a single component, and the absorption peak of the dichroic dye is in any wavelength band between 300nm and 2500nm.

12. The liquid crystal dimming device according to claim 1, characterized in that: The dichroic dye is a mixture of multiple components, and the absorption peak of each component is in any wavelength band between 300nm and 2500nm.

13. The liquid crystal dimming device according to claim 12, characterized in that: The absorption peaks of the components in the dichroic dye do not overlap.

14. The liquid crystal dimming device according to claim 1, characterized in that: The first transparent substrate and / or the second transparent substrate is flat glass, tempered glass, semi-tempered glass, float glass, or a plastic substrate film.

15. The liquid crystal dimming device according to claim 14, characterized in that: The plastic substrate film is selected from at least one of PET film, PI film, PTFE film, PP film, PC film, PVC film, PE film, PS film, PA film, PEN film, PMMA film and PBT film.

16. The liquid crystal dimming device according to claim 1, characterized in that: The material of the first transparent conductive layer and / or the second transparent conductive layer is any one of a metal oxide film, a metal nanowire conductive film, a metal grid, and a carbon-based conductive film.

17. The dimming device according to claim 1, characterized in that: At least one of the first and second transparent conductive layers is composed of at least one conductive region to which a voltage can be applied independently.

18. The liquid crystal dimming device according to claim 1, characterized in that: It also includes a first alignment layer and / or a second alignment layer disposed on the first transparent conductive base layer and / or the second transparent conductive base layer adjacent to the liquid crystal layer.

19. The liquid crystal dimming device according to claim 18, characterized in that: The material of the first alignment layer and / or the second alignment layer is any one of polyimide, polyvinyl alcohol, polyester, epoxy resin, polyurethane, polysilane, polystyrene and derivatives thereof.

20. The liquid crystal dimming device according to claim 18, characterized in that: The first alignment layer and / or the second alignment layer may be aligned in any one of a rubbing alignment method, a photo-controlled alignment method, an oblique evaporation method, and a LB film method.

21. The liquid crystal dimming device according to claim 18, characterized in that: The alignment type of the first alignment layer and / or the second alignment layer is any one of IPS, TN, STN or VA.

22. The liquid crystal dimming device according to claim 18, characterized in that: The alignment application operation of the first alignment layer and / or the second alignment layer is any one of a spin coating method, a dipping method, a relief printing method, a spray coating method or a slit coating method.

23. The liquid crystal dimming device according to claim 1, characterized in that: A spacing material is disposed between the first transparent conductive base layer and the second transparent conductive base layer. The spacing material is selected from at least one of resin, glass fiber and inorganic material. The spacing material is in a spherical shape, a rod shape or a mixed shape.

24. The liquid crystal dimming device according to claim 1, characterized in that: The thickness of the liquid crystal layer is 1-60 μm.

25. The liquid crystal dimming device according to claim 24, characterized in that: The thickness of the liquid crystal layer is 5-50 μm.

26. The liquid crystal dimming device according to any one of claims 1 to 25, characterized in that: The liquid crystal dimming device can be in at least three states for visible light and near-infrared light incident thereon: a high-transmittance, low-haze state, a low-coloration, low-haze state, and a high-coloration, high-haze state.

27. The liquid crystal dimming device according to claim 26, characterized in that: The high-clearance, low-haze state is obtained by continuously applying a first voltage; the low-coloration, low-haze state is obtained by applying a second voltage; and the high-coloration, high-haze state is obtained by applying a third voltage.

28. The liquid crystal dimming device according to claim 27, characterized in that: The first voltage is a continuous voltage, and the second voltage and the third voltage are pulse voltages.

29. The liquid crystal dimming device according to claim 28, characterized in that: The first voltage is an alternating voltage, the amplitude of the alternating voltage is 10-500V; the frequency of the alternating voltage is 20-10000Hz.

30. The liquid crystal dimming device according to claim 28, characterized in that: The second voltage is an alternating pulse voltage, which consists of a continuous pulse or a plurality of different or identical pulses, and the amplitude of the alternating pulse voltage is 10-300V; the frequency of the second voltage is 20-10000Hz; and the pulse width of the second voltage is 0.01-300s.

31. The liquid crystal dimming device according to claim 28, characterized in that: The third voltage is an alternating pulse voltage, which consists of a continuous pulse or a plurality of different or identical pulses, and the amplitude of the alternating pulse voltage is 10-300V; the frequency of the third voltage is 20-10000Hz; and the pulse width of the third voltage is 0.01-300s.

32. The liquid crystal dimming device according to claim 28, characterized in that: The sustained voltage includes a gradient voltage combined with a pulse voltage.

33. The liquid crystal dimming device according to claim 32, characterized in that: The pulse voltage amplitude, frequency, and pulse width are the same as or different from the second voltage and the third voltage.

34. The liquid crystal dimming device according to claim 27, characterized in that: The light transmittance of the high-definition, low-haze state is not less than 30%, and the haze is not higher than 5%; the light transmittance of the low-tinting, low-haze state is not higher than 50%, and the haze is not higher than 10%; the light transmittance of the high-tinting, high-haze state is not higher than 40%, and the haze is not lower than 60%.

35. A laminated liquid crystal dimming device, characterized in that: It comprises a first substrate, a first bonding layer, a liquid crystal dimming device, a second bonding layer and a second substrate which are arranged in sequence, and the liquid crystal dimming device is the liquid crystal dimming device as described in any one of claims 1-34.

36. The laminated liquid crystal dimming device according to claim 35, characterized in that: The first adhesive layer and the second adhesive layer are polymerizable high molecular compound layers with adhesive properties, and the high molecular compound layers are selected from any one or more of PVB, EVA, and SPU.

37. The laminated liquid crystal dimming device according to claim 35, characterized in that: The first substrate and the second substrate are made of the same or different materials.

38. The laminated liquid crystal dimming device according to claim 35, characterized in that: The materials of the first substrate and the second substrate are selected from one or more of glass, tempered glass, Low-e glass, special glass capable of blocking electromagnetic wave radiation, and plastic substrates.

39. A hollow liquid crystal dimming device, characterized in that: It includes a first substrate, a liquid crystal dimming device and a second substrate which are arranged in sequence, and also includes a hollow cavity located between the first substrate and the liquid crystal dimming device and / or between the liquid crystal dimming device and the second substrate. The liquid crystal dimming device is a liquid crystal dimming device as described in any one of claims 1 to 34.

40. The hollow liquid crystal dimming device according to claim 39, characterized in that: The hollow cavity is a vacuum.

41. The hollow liquid crystal dimming device according to claim 39, characterized in that: The hollow cavity is filled with any one or more of air, inert gas, aerogel or liquid.

42. The hollow liquid crystal dimming device according to claim 39, characterized in that: A hollow spacer material is arranged in the hollow cavity.

43. The hollow liquid crystal dimming device according to claim 42, characterized in that: The hollow spacer material is any one or more of strip, sheet, column, and spherical spacer materials made of polymer, metal, or non-metal.

44. The hollow liquid crystal dimming device according to claim 42, characterized in that: The hollow spacer material is bonded and fixed by an adhesive, and the adhesive is a polymerizable high molecular compound having bonding properties to glass and plastic substrates, and the high molecular compound is any one of PVB, EVA, and SPU.

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