A display structure

Abstract

The present invention provides a display structure, which includes: an anti-reflection layer, comprising a multi-layer dielectric having a refractive index gradient, the refractive index of the multi-layer dielectric increasing from top to bottom, the K value of the multi-layer dielectric being less than 0.5, the total thickness and the equivalent refractive index of the anti-reflection layer satisfying certain conditions for the three primary colors of red, green, and blue, such that the upper and lower electric fields at the position where the phase change layer is located below the anti-reflection layer are 0; a phase change layer, the optical loss of the phase change material used being less than a first preset threshold and the refractive index being greater than a second preset threshold, the phase change layer being located below the anti-reflection layer; a first metal layer, being a lossy metal for providing K value compensation, the first metal layer being located below the phase change layer; a second metal layer, for forming an FP cavity, the second metal layer being located below the first metal layer; and a dielectric layer, located below the second metal layer. The present invention realizes a reflective phase change display structure with high reflectivity, high color saturation, angle insensitivity, dynamic tunability, and simple structure.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change materials, and in particular to a display structure. Background Art

[0002] So far, various types of color filters have been developed, such as filters based on subwavelength gratings, nanoresonators, plasmonic nanostructures, photonic crystals, and multilayer thin films. However, due to their angle-sensitive spectral characteristics in practical applications, these filters are inevitably limited, which are manifested as spectral shifts of the central wavelength and reduced transmission and reflection efficiencies at oblique incidence.

[0003] For some nanophotonic devices, including metal nanoantenna arrays and plasmonic nanostructures, attempts have been made to mitigate their angular sensitivity. However, due to the inevitable need to use complex manufacturing techniques, such as electron beam or nanoimprint lithography, the reflective display based on the FP (Fabry - Perot) cavity structure has attracted much attention due to its simple structure, and the non-volatile display using phase change materials has attracted much attention due to its advantages such as low power consumption and dynamic tunability. However, how to achieve vivid, highly saturated, and dynamically tunable RGB reflective colors using low-loss and high-reflectivity phase change materials is still a challenge. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a display structure.

[0005] The present invention provides a display structure, including:

[0006] An antireflection layer, including a multilayer dielectric having a refractive index gradient, the refractive index of the multilayer dielectric increasing from top to bottom, the K value of the multilayer dielectric being less than 0.5, and the total thickness and equivalent refractive index of the antireflection layer satisfying certain conditions in the three primary colors of red, green, and blue, such that the upper and lower electric fields at the position where the phase change layer is located below the antireflection layer are 0;

[0007] The phase change layer, the phase change material used in the phase change layer having an optical loss less than a first preset threshold and a refractive index greater than a second preset threshold, the N value of the phase change material being greater than 1 in the visible light region, the larger the better, and the K value being less than 1 in the visible light region, the smaller the better, and the phase change layer being located below the antireflection layer;

[0008] A first metal layer, which is a lossy metal for providing K value compensation, and the first metal layer is located below the phase change layer;

[0009] A second metal layer, which is used to form an FP cavity, and the second metal layer is located below the first metal layer;

[0010] The dielectric layer is located under the second metal layer.

[0011] According to a display structure provided by the present invention, when the color generated by the display structure is red or blue, the total thickness of the antireflection layer is λ 0 / (4n);

[0012] When the color generated by the display structure is green, the total thickness of the antireflection layer is λ 0 / (8n);

[0013] Wherein, λ 0 is the wavelength to be suppressed by the antireflection layer, and n is the effective refractive index of the antireflection layer.

[0014] According to a display structure provided by the present invention, the thickness of the dielectric layer is λ c / (2n 1 ), λ c is the target wavelength of the color generated by the display structure, and n 1 is the refractive index of the dielectric layer.

[0015] According to a display structure provided by the present invention, the effective thickness formed by the thickness of the phase change material and the thickness of the first metal layer is less than λ c / (4n 2 π), λ c is the target wavelength of the color generated by the display structure, and n 2 is the effective refractive index of the phase change material and the first metal layer. The K value of the first metal layer is greater than the N value of the first metal layer, and the K value of the first metal layer is greater than 1.

[0016] According to a display structure provided by the present invention, the phase change layer is one or more layers. Each phase change layer includes a phase change material and an electrode layer deposited on the lower side of the phase change material. The voltage thresholds of the phase change materials in each phase change layer are different;

[0017] The first metal layer is one or more layers.

[0018] According to a display structure provided by the present invention, the phase change material is an alloy compound composed of elements in Group VI and elements in Groups III to V. The alloy compound is doped with elements in Group Ib.

[0019] According to a display structure provided by the present invention, the phase change material includes Sb 2 Se 3 and one or more of alloys such as Sb 2 S 3 etc. The percentage of each atom is adjustable;

[0020] The dielectric layer includes TiO 2 , Ta 2 O 5 and LaTiO 3 and other transparent dielectrics. The K value of the dielectric is less than 1 and approaches 0.

[0021] According to a display structure provided by the present invention, the second metal layer is a simple substance formed by one element in Group III to V of the periodic table or a compound composed of multiple elements in any ratio.

[0022] According to a display structure provided by the present invention, the second metal layer is a metal material with electrothermal conductivity among metals such as Ag, Al, and W.

[0023] According to a display structure provided by the present invention, it further includes a reflective layer. The reflective layer is located below the dielectric layer, and the thickness of the reflective layer is greater than 50 nm.

[0024] A display structure provided by the present invention, a reflective phase change display structure based on a low-loss and high-refractive-index phase change material, is a thin film composed of a dielectric, a metal forming an FP cavity, a lossy metal providing K value compensation, and a low-loss and high-refractive-index phase change material. It is designed to form a reflective phase change display with high reflectivity, high color saturation, and angle insensitivity. This design mainly utilizes the high refractive index of the phase change material itself and the property of the high extinction coefficient of the metal providing K value compensation to absorb light other than the target area, allowing the light in the target area to pass through, combined with an antireflection layer composed of a multi-layer dielectric with a refractive index gradient on the top layer, thereby achieving the effects of high reflectivity, high color saturation, angle insensitivity, dynamic tunability, and simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is a schematic diagram of the display structure provided by the present invention;

[0027] Figure 2 is a schematic diagram of the spectrum of the display structure provided by the present invention generating blue;

[0028] Figure 3 is a schematic diagram of the spectrum of the display structure provided by the present invention generating green;

[0029] Figure 4 is a schematic diagram of the spectrum of the display structure provided by the present invention generating red;

[0030] Figure 5 It is a schematic diagram showing the angle insensitivity of the display structure provided by the present invention for generating blue light;

[0031] Figure 6 It is a schematic diagram showing the angle insensitivity of the display structure provided by the present invention for generating green light;

[0032] Figure 7 It is a schematic diagram showing the angle insensitivity of the display structure provided by the present invention for generating red light.

[0033] Reference numerals:

[0034] 101: Substrate; 102: Reflective layer; 103: Third dielectric layer; 104: Second metal layer; 105: First metal layer; 106: Phase change layer; 107: Second dielectric layer; 108: First dielectric layer. Detailed implementation manners

[0035] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0036] The following Figure 1 describes a display structure of the present invention, including:

[0037] An antireflection layer, including a multi-layer dielectric having a refractive index gradient, the refractive index of the multi-layer dielectric increases from top to bottom, the K value of the multi-layer dielectric is less than 0.5, and the total thickness and equivalent refractive index of the antireflection layer satisfy certain conditions for the three primary colors of red, green, and blue, so that the upper and lower electric fields at the position of the phase change layer below the antireflection layer are 0;

[0038] The phase change layer 106, the optical loss of the phase change material used in the phase change layer 106 is less than a first preset threshold and the refractive index is greater than a second preset threshold, the N value of the phase change material is greater than 1 in the visible light region, the larger the better, and the K value is less than 1 in the visible light region, the smaller the better, and the phase change layer 106 is located below the antireflection layer;

[0039] The first metal layer 105, which is a lossy metal for providing K value compensation, and the first metal layer 105 is located below the phase change layer 106;

[0040] The second metal layer 104, which is used to form an FP cavity, and the second metal layer 104 is located below the first metal layer 105;

[0041] A dielectric layer is located under the second metal layer 104.

[0042] The upper anti-reflection layer may include a first dielectric layer 108 and a second dielectric layer 107, and the first dielectric layer 108 is located above the second dielectric layer 107. The K value of each dielectric layer in the anti-reflection layer is less than 0.5, preferably 0.

[0043] To minimize absorption loss and achieve high reflectivity, the top anti-reflection layer can reduce reflection in the non-peak region by introducing an additional resonant cavity.

[0044] The phase change material used in the phase change layer 106 is a phase change material with low loss and high refractive index. A phase change material with low loss and high refractive index refers to a phase change material with an N value greater than 1 in the visible light region, the larger the better, and a K value less than 1 in the visible light region, and the smaller the better.

[0045] The first metal layer 105 is a high-loss metal that provides K value compensation. The metal that provides K value compensation requires that the K value of its material itself is greater than the N value and greater than 1. The second metal layer 104 located below the first metal layer 105 is used to form an FP cavity.

[0046] The dielectric layer located under the second metal layer 104 is the third dielectric layer 103. Below the third dielectric layer 103 is a reflective layer 102, and below the reflective layer 102 is a substrate 101.

[0047] The phase change material of the phase change layer 106 can be switched between the crystalline state and the amorphous state under electrical stimulation or laser stimulation, thereby changing the transmittance and reflectivity of the phase change layer 106. Metal Ag is deposited under the phase change layer 106, and the phase change layer 106 can control the crystallization state of the phase change material by applying a voltage to Ag.

[0048] Specifically, apply a medium-strength pulsed voltage or laser pulse to the phase change layer 106. The phase change material is heated to a temperature range above the crystallization temperature and below the melting temperature under the action of the current or laser pulse, and maintained for a certain time. At this time, the crystal lattice is arranged orderly to form a crystalline state, realizing the transformation from amorphous to crystalline.

[0049] Apply a short and strong voltage or laser pulse to the phase change layer 106 to raise the temperature of the phase change material above the melting temperature, destroy the long-range order of the crystalline state, and the very short falling edge of the pulse causes the phase change material to be rapidly cooled below the crystallization temperature, fixing the phase change material in the amorphous state, realizing the transformation from the crystalline state to the amorphous state. The gray level of the display device is regulated by the changes in the transmittance and reflectivity when the phase change material of the phase change layer 106 is mutually transformed between the amorphous state and the crystalline state.

[0050] The phase change layer 106 of the phase change filter component has a large difference in N and K in different states. The phase change material is stable in the crystalline and amorphous states. Therefore, when the phase change material is in a stable state, the voltage or laser can be removed, so the power consumption of the entire display device during the display process is very low.

[0051] The FP structure that generates colors based on a phase change material with low loss and high refractive index consists of a dielectric - phase change material - lossy metal - metal - phase change material - metal (MDM) cavity or is composed of multiple cavities of the same type or different types. The design of the cavity should be such that a change in the state of the phase change material does not cause a large shift in the color peak position, but only changes in the corresponding wavelength band, that is, changes in the displayed gray level. By applying a voltage or heating through the electrode layer, the crystal structure of the phase change material can be changed, thereby achieving the adjustment of the peak and position of the cavity.

[0052] Through this design, a reflective display device based on a phase change material with low loss and high refractive index can produce a display device with high reflectivity, high color saturation, and angle insensitivity, so as to meet the requirements for the regulation of high color saturation and high reflectivity in the reflective display market based on phase change materials, etc.

[0053] In this embodiment, the reflective phase change display structure based on a phase change material with low loss and high refractive index is a thin film composed of a dielectric, the metal constituting the FP cavity, a lossy metal providing compensation for the K value, and a phase change material with low loss and high refractive index. It is designed to form a reflective phase change display with high reflectivity, high color saturation, and angle insensitivity. This design mainly utilizes the high refractive index of the phase change material itself and the property of the high extinction coefficient of the metal providing K value compensation to absorb light other than the target area, while allowing the light in the target area to pass through, combined with an antireflection layer composed of a dielectric with a multi - layer refractive index gradient on the top layer, so as to achieve the effects of high reflectivity, high color saturation, angle insensitivity, dynamic tunability, and simple structure. This structure has good application potential in various fields such as micro - nano displays, anti - counterfeiting measures, reflective color filters, and decorations, overcomes the inherent limitations of the existing structure, has great significance in technological progress, and opens up new possibilities for the further development of phase change display technology.

[0054] Based on the above - mentioned embodiment, in this embodiment, when the color generated by the display structure is red or blue, the total thickness of the antireflection layer is λ 0 / (4n);

[0055] When the color generated by the display structure is green, the total thickness of the antireflection layer is λ 0 / (8n);

[0056] where λ 0 is the wavelength that the antireflection layer needs to suppress, and n is the effective refractive index of the antireflection layer.

[0057] Such a setting enables strong resonance to occur in the target peak region while being attenuated in the non-target peak region.

[0058] Based on the above embodiments, in this embodiment, the thickness of the dielectric layer is λ c / (2n 1 ), where λ c is the target wavelength that generates color for the display structure, and n 1 is the refractive index of the dielectric layer.

[0059] Based on the above embodiments, in this embodiment, the effective thickness formed by the thickness of the phase change material and the thickness of the first metal layer 105 is less than λ c / (4n 2 π), where λ c is the target wavelength that generates color for the display structure, n 2 is the effective refractive index of the phase change material and the first metal layer 105. The K value of the first metal layer 105 is greater than the N value of the first metal layer 105, and the K value of the first metal layer 105 is greater than 1.

[0060] In the reflective phase change display structure, the effective thickness formed by the thickness of the phase change material and the thickness of the metal providing the compensated K value should be less than λ c / (4n 2 π), but it cannot be too thin. It is necessary to ensure that the light absorption at the target peak wavelength is very small, while the light absorption in the non-target peak wavelength band is very large. In this type of design, all low-loss, high-refractive-index phase change materials can be applied to this design to form a high-reflectivity phase change display device.

[0061] Based on the above embodiments, in this embodiment, the phase change layer 106 is one or more layers, and each phase change layer 106 includes a phase change material and an electrode layer deposited on the lower side of the phase change material. The voltage thresholds of the phase change materials in each phase change layer are different;

[0062] The first metal layer 105 is one or more layers.

[0063] In this embodiment, there is at least one layer of phase change material, and there is at least one layer of lossy metal that provides the compensated K value for the phase change material. The electrode layers between adjacent two layers of phase change materials can be shared. The material of the conductive electrode layer can be a metal material with heat generation by conduction such as Ag, Al, W, etc.

[0064] Based on the above embodiments, in this embodiment, the phase change material is an alloy compound composed of elements in the sixth main group and elements in the third to fifth main groups, and the alloy compound is doped with elements in the first main group of the Ib group.

[0065] Based on the above embodiments, the phase change material in this embodiment may include the following chalcogenide compounds and their alloys, including but not limited to Sb 2 Se 3 、Sb 2 S 3 and other phase change materials with low loss and high refractive index characteristics in one or more of the alloys, where the percentage of each atom in the above chemical formulas is adjustable. The phase change material layer may further include at least one dopant, such as C, N. Preferably, the phase change material is selected as Sb 2 Se 3 , which has high loss and high refractive index in the visible light range, and Sb 2 Se 3 has good thermal stability.

[0066] The phase change material must have low loss and high refractive index, that is, the average value of the K value is less than 1 in the visible light band, the smaller the better, the N value is greater than 1 in the visible light band, and the larger the better. The metal providing the K value compensation needs to have a K value greater than the N value and greater than 1 for its material itself.

[0067] The thickness of the phase change layer 106 is less than 50 nm. Since the increase in the thickness of the phase change layer 106 will reduce the transmittance of visible light and the temperature required for the phase change material to crystallize is also higher, a more appropriate thickness is within 30 nm. The phase change material of the phase change layer 106 can be driven by laser or voltage. When driven by voltage, a voltage is applied to the transparent electrodes on both sides of the phase change layer 106 to cause the phase change of the phase change material.

[0068] The dielectric layer is composed of TIO 2 、Ta 2 O 5 、LaTIO 3 and other low-loss dielectrics (K value less than 1, tending to 0).

[0069] Based on the above embodiments, in this embodiment, the second metal layer constituting the FP cavity is a simple substance formed by one element in the main groups III to V or a compound composed of multiple elements in any ratio.

[0070] Based on the above embodiments, in this embodiment, the second metal layer is a metal material such as Ag, Al, W that has conductive heat generation.

[0071] Based on the above embodiments, in this embodiment, a reflection layer 102 is further included. The reflection layer 102 is located below the dielectric layer, and the thickness of the reflection layer 102 is greater than 50 nm.

[0072] The thickness of the first metal layer 105 is less than 15 nm. The main function of this layer is to compensate for the defect of the low-loss, high-refractive-index phase change material with a small K value, and further improve the color purity.

[0073] The thickness of the second metal layer 104 should be less than 30 nm. This layer is mainly used to form a resonant cavity with the third dielectric layer 103. The display structure mainly controls the color change by changing the thickness of Ta 2 O 5 in the bottom third dielectric layer 103, so as to realize the color change within the color gamut.

[0074] Optionally, Figure 1 the phase change material of the display structure is Sb 2 Se 3 ; the second metal layer 104 is Ag; the lossy metal used for the first metal layer 105 is Cr. Among them, Sb 2 Se 3 is an ultra-thin phase change material with low optical loss and high refractive index; Ag is a high-reflectivity material; Cr is a lossy metal with a high extinction coefficient; the dielectric materials are Ta 2 0 5 and MgF 2 .

[0075] As Figure 1 shown, when the reflective display structure generates blue, the substrate 101 of the reflective display structure is silicon or glass or a flexible substrate; the reflective layer 102 Ag of the reflective display structure is 100 nm; the third dielectric layer 103 Ti 2 O 3 of the reflective display structure is 55 nm; the second metal layer 104 Ag of the reflective display structure is 6 nm; the first metal layer 105 Cr of the reflective display structure is 5 nm; the phase change layer 106 Sb 2 Se 3 of the reflective display structure is 6 nm; the second dielectric layer 107 Ti 2 O 3 of the reflective display structure is 12 nm; the third dielectric layer 108 MgF 2 of the reflective display structure is 233 nm.

[0076] As Figure 1 shown, when the reflective display generates green, the substrate 101 of the reflective display structure is silicon or glass or a flexible substrate; the reflective layer 102 Ag of the reflective display structure is 100 nm; the third dielectric layer 103 Ti 2 O 3is 70 nm, the second metal layer 104Ag of the reflective display structure is 10 nm, the first metal layer 105Cr of the reflective display structure is 7 nm, and the phase change layer 106Sb of the reflective display structure 2 Se 3 is 8 nm, the second dielectric layer 107Ti of the reflective display structure 2 O 3 is 14 nm, the third dielectric layer 108MgF of the reflective display structure 2 is 140 nm.

[0077] As Figure 1 shown, when the reflective display produces red, the substrate 101 of the reflective display structure is silicon or glass or a flexible substrate, the reflective layer 102Ag of the reflective display structure is 100 nm, and the third dielectric layer 103Ti of the reflective display structure 2 O 3 is 110 nm, the second metal layer 104Ag of the reflective display structure is 15 nm, the first metal layer 105Cr of the reflective display structure is 6 nm, and the phase change layer 106Sb of the reflective display structure 2 Se 3 is 6 nm, the second dielectric layer 107Ti of the reflective display structure 2 O 3 is 32 nm, and the third dielectric layer 108MgF of the reflective display structure 2 is 233 nm.

[0078] Figure 2 Shown is Figure 1 the spectral diagram of the structural parameters corresponding to the structure that produces blue, with a reflectivity of over 80%. Figure 3 Shown is Figure 1 the spectral diagram of the structural parameters corresponding to the structure that produces green, with a reflectivity of over 85%. As Figure 4 shown is Figure 1 the spectral diagram of the structural parameters corresponding to the structure that produces red, with a reflectivity of over 85%.

[0079] As Figure 5 shown is Figure 1 the angle-insensitive diagram of the structural parameters corresponding to the structure that produces blue, with an angle insensitivity of over 60 degrees. As Figure 6 shown is Figure 1 the angle-insensitive diagram of the structural parameters corresponding to the structure that produces green, with an angle insensitivity of over 60 degrees. As Figure 7 shown is Figure 1 the angle-insensitive diagram of the structural parameters corresponding to the structure that produces red, with an angle insensitivity of over 60 degrees.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A display structure, characterized in that: include: The anti-reflection layer comprises a multilayer medium with a refractive index gradient, wherein the refractive index of the multilayer medium increases from small to large from top to bottom, the K value of the multilayer medium is less than 0.5, and the total thickness and equivalent refractive index of the anti-reflection layer meet certain conditions when the three primary colors of red, green and blue are used, so that the upper and lower electric fields at the position where the phase change layer below the anti-reflection layer is located are 0; The phase change layer, the phase change material used in the phase change layer has an optical loss less than a first preset threshold and a refractive index greater than a second preset threshold, the N value of the phase change material is greater than 1 in the visible light region, the larger the better, and the K value is less than 1 in the visible light region, the smaller the better, the phase change layer is located below the anti-reflection layer; A first metal layer, which is a lossy metal providing K value compensation, and the first metal layer is located below the phase change layer; A second metal layer, used to form a FP cavity, the second metal layer being located below the first metal layer; a dielectric layer, located below the second metal layer; When the color generated by the display structure is red or blue, the total thickness of the anti-reflection layer is λ0 / (4n); When the color generated by the display structure is green, the total thickness of the anti-reflection layer is λ0 / (8n); Wherein, λ0 is the wavelength to be suppressed by the anti-reflection layer, and n is the effective refractive index of the anti-reflection layer; The thickness of the dielectric layer is λ c / (2n1),λ c is the target wavelength of the color produced by the display structure, and n1 is the refractive index of the medium layer; The effective thickness formed by the thickness of the phase change material and the thickness of the first metal layer is less than λ c / (4n2π),λ c is the target wavelength of the color generated by the display structure, n2 is the effective refractive index of the phase change material and the first metal layer, the K value of the first metal layer is greater than the N value of the first metal layer, and the K value of the first metal layer is greater than 1.

2. The display structure according to claim 1, characterized in that: The phase change layer is one or more layers, each phase change layer comprises a phase change material and an electrode layer deposited on the lower side of the phase change material, and the voltage threshold of the phase change material in each phase change layer is different; The first metal layer is one layer or multiple layers.

3. The display structure according to claim 1, characterized in that: The phase change material is an alloy compound composed of a VI main group element and a III to V main group element, and the Ib main group element is doped into the alloy compound.

4. The display structure according to claim 3, characterized in that: The phase change material includes one or more of Sb2Se3 and Sb2S3 alloy, wherein the percentage of each atom is adjustable; The dielectric layer includes a dielectric selected from the group consisting of TIO2, Ta2O5 and LaTIO3, and a K value of the dielectric is less than 1 and approaches 0.

5. The display structure according to claim 1, characterized in that: The second metal layer is a simple substance formed by one element from the main groups III to V or a compound composed of multiple elements in any proportion.

6. The display structure according to claim 5, characterized in that: The second metal layer is a metal material having electrical conductivity and heat generation among Ag, Al and W.

7. The display structure according to claim 1, characterized in that: It also includes a reflective layer, which is located below the dielectric layer and has a thickness greater than 50 nm.

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