A display device

Abstract

The present invention provides a display device, comprising: an anti-reflection layer including a multi-layer dielectric having a refractive index gradient, wherein the refractive index of the multi-layer dielectric gradually increases from top to bottom, the K value of the multi-layer dielectric is less than a first preset threshold, the total thickness and the equivalent refractive index of the anti-reflection layer satisfy 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; the phase change layer, wherein the optical loss of the phase change material used in the phase change layer is greater than a second preset threshold and the refractive index is greater than a third preset threshold, the N value of the phase change material is greater than 1 in the visible light region and the K value is greater than 1 in the visible light region, and the phase change layer is located below the anti-reflection layer; a dielectric layer located below the phase change layer; and a metal layer for forming an FP cavity. The present invention realizes a reflective phase change display device with high reflectivity, high color purity, angle insensitivity, and dynamic tunability based on a high-loss and high-refractive-index phase change material.

Description

Technical Field

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

[0002] Currently, reflective color displays are mainly divided into two types. One is based on a plasma structure that has perfect absorption within a specific wavelength range of visible light. The plasma structure mainly uses a three-layer metal-insulator-metal (MIM) thin film stack, where the top layer is a nano-patterned metal surface and is separated from the bottom metal film by a dielectric layer. To fabricate such a filter, complex lithography procedures must be used, which limits their use in large-scale applications. The second type of reflective color filter consists of a metal-dielectric multi-layer thin film based on Fabry-Perot (F–P) cavity resonance. Generally, such an F–P resonator consists of a lossless core dielectric, a partially reflective top metal layer, and an optically thick and highly reflective mirror. The perfect absorption in the F–P resonator is closely related to the multiple round-trip phase delays of electromagnetic waves in the resonator.

[0003] Compared with plasma color filters, the F–P cavity-based color filters do not involve noble metal nanostructures on the order of 100 nanometers. Therefore, more flexible processes can be used to fabricate the structural colors generated by the resonant interaction between light and nanostructures in practical applications. Recently, they have received increasing attention due to their potential applications in various fields, including color printing, display / imaging, etc. Compared with existing color filters that use chemical pigments or organic dyes, structural color filters offer unique advantages such as non-toxicity, non-fading, thin thickness, high scalability, high resolution, and easy adjustment.

[0004] However, the prior art mainly obtains high reflectivity and high color saturation by metasurfaces and gratings or by introducing semiconductor absorption media, which requires introducing an additional absorption metal layer, has a complex structure, high cost, and such a structure has non-tunability for colors. Summary of the Invention

[0005] The present invention provides a display device to solve the defects in the prior art that reflective displays need to introduce an additional absorption metal layer and have inherent limitations in display, and to implement a reflective phase change display device with high reflectivity, high color purity, angle insensitivity, and dynamic tunability based on high-loss, high-refractive-index phase change materials.

[0006] The present invention provides a display device, comprising:

[0007] The antireflection layer includes a multi-layer dielectric with a refractive index gradient, where the refractive index of the multi-layer dielectric gradually increases from top to bottom, the K value of the multi-layer dielectric is less than a first preset threshold, and the total thickness and equivalent refractive index of the antireflection layer meet certain conditions for the three primary colors of red, green, and blue, such that the upper and lower electric fields at the position of the phase change layer below the antireflection layer are 0;

[0008] The phase change layer, where the optical loss of the phase change material used in the phase change layer is greater than a second preset threshold and the refractive index is greater than a third preset threshold, the N value of the phase change material is greater than 1 in the visible light region and the K value is greater than 1 in the visible light region, and the phase change layer is located below the antireflection layer;

[0009] The dielectric layer is located below the phase change layer;

[0010] The metal layer is used to form the FP cavity.

[0011] According to a display device provided by the present invention, when the color generated by the display device is red or blue, the total thickness of the antireflection layer is λ0 / (4n);

[0012] When the color generated by the display device is green, the total thickness of the antireflection layer is λ0 / (8n);

[0013] Wherein, λ0 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 device provided by the present invention, the thickness of the dielectric layer is λ c / (2n1), where λ c is the target wavelength of the color generated by the display device, and n1 is the refractive index of the dielectric layer.

[0015] According to a display device provided by the present invention, the thickness of the phase change material is less than λ c / (4n2π), where λ c is the target wavelength of the color generated by the display device, and n2 is the refractive index of the phase change material.

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

[0017] According to a display device provided by the present invention, 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.

[0018] A display device provided by the present invention, wherein the phase change material includes one or more of AgInSbTe, InSbTe, GeTe, SbTe, BiTe, InSb, InSe, GeSb, SbSe, GaSb, GeSbTe, AgInSbTe, InSbTe, AgSbTe, SiTe, SnTe, SnSb; wherein, the atomic percentage of each phase change material is adjustable.

[0019] A display device provided by the present invention, wherein the dielectric layer includes a dielectric with an optical loss less than a fourth preset threshold.

[0020] A display device provided by the present invention, wherein the metal layer is a single element formed by an element in Group III to V of the periodic table or a compound composed of multiple elements.

[0021] A display device provided by the present invention, wherein the thickness of the bottom metal layer serving as a reflective layer in the metal layer is greater than 50 nm.

[0022] The display device provided by the present invention realizes a display structure with high reflectivity, high color saturation, and angle insensitivity by using a phase change material with high loss and high refractive index. It has the characteristics of high reflectivity, high color saturation, angle insensitivity, dynamic tunability, and simple structure, and can be well applied in various fields such as micro-nano displays, anti-counterfeiting measures, reflective color filters, and decorations; this structure does not require the introduction of an additional absorption metal layer, overcomes the inherent limitations of the existing structure, has great technological progress significance, and opens up new possibilities for the further development of phase change display technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic diagram of the display device provided by the present invention;

[0025] Figure 2 It is a schematic diagram of the display device provided by the present invention that generates red;

[0026] Figure 3 It is a schematic diagram of the display device provided by the present invention that generates green;

[0027] Figure 4 It is a schematic diagram of the display device provided by the present invention that generates blue;

[0028] Figure 5 It is a schematic diagram of the spectrum of a display device that generates red provided by the present invention;

[0029] Figure 6 It is a schematic diagram of the spectrum of a display device that generates green provided by the present invention;

[0030] Figure 7 It is a schematic diagram of the spectrum of a display device that generates blue provided by the present invention;

[0031] Figure 8 It is a schematic diagram of the angle insensitivity of a display device that generates red provided by the present invention;

[0032] Figure 9 It is a schematic diagram of the angle insensitivity of a display device that generates green provided by the present invention;

[0033] Figure 10 It is a schematic diagram of the angle insensitivity of a display device that generates blue provided by the present invention.

[0034] Reference numerals:

[0035] 101: Substrate of the display device; 102: Second metal layer of the display device; 103: Third dielectric layer of the display device; 104: First metal layer of the display device; 105: Phase change layer of the display device; 106: Second dielectric layer of the display device; 107: First dielectric layer of the display device; 201: Substrate of the display device that generates red; 202: Second metal layer of the display device that generates red; 203: Third dielectric layer of the display device that generates red; 204: First metal layer of the display device that generates red; 205: Phase change layer of the display device that generates red; 206: Second dielectric layer of the display device that generates red; 207: First dielectric layer of the display device that generates red; 301: Substrate of the display device that generates green; 302: Second metal layer of the display device that generates green; 303: Third dielectric layer of the display device that generates green; 304: First metal layer of the display device that generates green; 305: Phase change layer of the display device that generates green; 306: Second dielectric layer of the display device that generates green; 307: First dielectric layer of the display device that generates green; 401: Substrate of the display device that generates blue; 402: Second metal layer of the display device that generates blue; 403: Third dielectric layer of the display device that generates blue; 404: First metal layer of the display device that generates blue; 405: Phase change layer of the display device that generates blue; 406: Second dielectric layer of the display device that generates blue; 407: First dielectric layer of the display device that generates blue. Detailed implementation manners

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Combine the following Figure 1 A display device of the present invention is described, comprising:

[0038] An anti-reflection layer, comprising a multilayer medium with a refractive index gradient, wherein the refractive index of the multilayer medium gradually increases from top to bottom, the K value of the multilayer medium is less than a first preset threshold, and the total thickness and the 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;

[0039] The phase change layer 105, the optical loss of the phase change material used in the phase change layer 105 is greater than the second preset threshold value and the refractive index is greater than the third preset threshold value, the N value of the phase change material is greater than 1 in the visible light region and the K value is greater than 1 in the visible light region, and the phase change layer is located below the anti-reflection layer;

[0040] a dielectric layer, located below the phase change layer;

[0041] Metal layer, used to form the FP cavity.

[0042] The upper anti-reflection layer may include a first dielectric layer 107 and a second dielectric layer 106, wherein the first dielectric layer 107 is located above the second dielectric layer 106. The K value of each dielectric layer in the anti-reflection layer is less than a first preset threshold, such as 0.5, and the K value of the dielectric is preferably 0.

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

[0044] The phase change material used in the phase change layer 105 is a high-loss, high-refractive-index phase change material. The N value of the phase change material is greater than 1 in the visible light region, and the larger the better, and the K value is greater than 1 in the visible light region, and the larger the better.

[0045] The dielectric layer below the phase change layer 105 may be the third dielectric layer 103. The metal layer includes a first metal layer 104 and a second metal layer 102. The first metal layer 104 is located between the third dielectric layer 103 and the phase change layer 105, and the second metal layer 102 is located below the third dielectric layer 103 as a reflective layer. A substrate 101 is also included below the second metal layer 102.

[0046] The phase change material of the phase change layer 105 can be switched between the crystalline state and the amorphous state under electrical stimulation or laser stimulation, thereby causing changes in the transmittance and reflectance of the phase change layer 105. A first metal layer 104 is deposited under the phase change layer 105, and the phase change layer 105 can control the crystallization state of the phase change material by applying a voltage to the first metal layer 104Ag.

[0047] Specifically, apply a medium-strength pulsed voltage or laser pulse to the phase change layer 105. Under the action of the current or laser pulse, the temperature of the phase change material rises to a temperature range above the crystallization temperature and below the melting temperature, and remains for a certain period of time. At this time, the lattice is arranged orderly to form a crystalline state, realizing the transformation from the amorphous state to the crystalline state.

[0048] Apply a short and strong voltage or laser pulse to the phase change layer 105 to raise the temperature of the phase change material above the melting temperature, destroying the long-range order of the crystalline state. 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 grayscale of the display device is adjusted by the changes in the transmittance and reflectance when the phase change material of the phase change layer 105 is mutually transformed between the amorphous state and the crystalline state.

[0049] N and K of the phase change layer 105 differ greatly in different states. The phase change material is stable in the crystalline state and the amorphous state. The voltage or laser can be removed in the stable state of the phase change material, so the power consumption of the entire display device during the display process is low.

[0050] The FP structure that generates colors by the phase change material based on the high-loss and high-refractive-index phase change material consists of a dielectric-phase change material-metal-dielectric-metal (MDM) cavity, or is composed of multiple cavities of the same type or different types. The design of this cavity should achieve that the 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 the grayscale of the display. By applying a voltage or heating to the electrode layer of the phase change material, the crystal structure of the phase change material can be changed, thereby realizing the adjustment of the peak and position of this cavity. The FP structure enables the display device to have advantages such as simple structure and simple manufacturing process.

[0051] In the field of reflective displays based on phase change materials, due to its dynamic tunability, it has broad application prospects. The existing technologies mainly obtain high reflectivity and high color saturation through metasurfaces and gratings or by introducing semiconductor absorption media. Therefore, how to utilize the characteristics of the phase change material itself to achieve vivid, highly saturated and dynamically tunable RGB reflective colors remains a challenge.

[0052] In this embodiment, the reflective phase change display device based on a high-loss and high-refractive-index phase change material is a thin film composed of a dielectric, a metal, and a high-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 to meet the requirements for regulating high color saturation and high reflectivity in the reflective display market based on phase change materials, etc. This design mainly utilizes the properties of the high refractive index and high extinction coefficient of the phase change material itself to absorb light other than the target area, allowing the light in the target area to pass through, thereby achieving the effects of high reflectivity, high color saturation, and angle insensitivity.

[0053] In this embodiment, a display structure with high reflectivity, high color saturation, and angle insensitivity is achieved through a phase change material with high loss and high refractive index. It has the characteristics of high reflectivity, high color saturation, angle insensitivity, dynamic tunability, and simple structure, and can be well applied in various fields such as micro-nano displays, anti-counterfeiting measures, reflective color filters, and decorations; this structure does not require the introduction of an additional absorption metal layer, 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 embodiment, in this embodiment, when the color generated by the display device is red or blue, the total thickness of the anti-reflection layer is λ0 / (4n);

[0055] When the color generated by the display device is green, the total thickness of the anti-reflection layer is λ0 / (8n). Such a setting enables strong resonance to occur in the target peak region while weakening in the non-target peak region;

[0056] 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.

[0057] Based on the above embodiment, in this embodiment, the thickness of the dielectric layer is λ c / (2n1), where λ c is the target wavelength of the color generated by the display device, and n1 is the refractive index of the dielectric layer.

[0058] Based on the above embodiment, in this embodiment, the thickness of the phase change material is less than λ c / (4n2π), where λ c is the target wavelength of the color generated by the display device, and n2 is the refractive index of the phase change material.

[0059] The thickness of the phase change material is less than λ c / (4n2π), but it cannot be too thin. It is necessary to ensure that the absorption of light at the target peak wavelength is very small, while the absorption of light in the non-target peak band is very large.

[0060] The thickness of the phase change material is less than λ c / (4n2π), so as to ensure less light absorption in the target area.

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

[0062] Optionally, 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.

[0063] 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 Ib.

[0064] Based on the above embodiments, in this embodiment, the phase change material includes AgInSbTe and / or InSbTe alloy, but is not limited to these two materials, and the percentage of each atom in the phase change material is adjustable.

[0065] The phase change material of the phase change layer 105 may include the following chalcogenide compounds and their alloys, including but not limited to AgInSbTe, InSbTe, AgSbTe, Ag2In4Sb 76 Te 17 (AIST) phase change materials with high loss and high refractive index characteristics.

[0066] In addition, the atomic percentages in the above chemical formulas are variable. The phase change layer 105 may further contain at least one dopant, such as C, N.

[0067] Preferably, the phase change material can be AgInSbTe, which has high loss and high refractive index in the visible light range, and AgInSbTe has good thermal stability.

[0068] The thickness of the phase change material used in the phase change layer 105 is less than 50 nm. Since the increase in the thickness of the phase change material will reduce the transmittance of visible light and the temperature required for the crystallization of the phase change material is also higher, a more appropriate thickness is within 30 nm.

[0069] The phase change material of the phase change layer 105 can be driven by laser or by voltage. When driven by voltage, a voltage is applied to the transparent electrodes on both sides of the phase change material to cause the phase change of the phase change material.

[0070] The thickness of the first metal layer 104 is less than 30 nm. This layer mainly forms a resonant cavity with the third dielectric layer 103. The display device mainly controls the color change by changing the thickness of the underlying third dielectric layer 103 Ta2O5, thereby realizing the color change within the color gamut.

[0071] Based on the above embodiments, in this embodiment, the dielectric layer includes a dielectric with an optical loss less than a fourth preset threshold.

[0072] The dielectric layer can be a low-loss dielectric such as TIO2, Ta2O5, LaTIO3, etc.

[0073] Based on the above embodiments, in this embodiment, the metal layer is a simple substance formed by one element in the main groups III to V of elements or a compound formed by multiple elements in any proportion.

[0074] Based on the above embodiments, in this embodiment, the thickness of the metal layer at the bottom layer serving as the reflective layer is greater than 50 nm.

[0075] Figure 1 The phase change material of the display device can be AgInSbTe, and the metal layer can be Ag. Among them, AgInSbTe is an ultra-thin phase change material with strong optical loss and high refractive index, Ag is a high-reflectivity material, the dielectric material used for the dielectric layer 203 can be Ta205, and the dielectric materials used for the anti-reflection layer can be Ta205 and MgF2.

[0076] As Figure 2 shown, in the schematic diagram of the display device that generates red, the substrate 201 can be silicon, glass, or a flexible substrate; the second metal layer 202 can be Ag, and the thickness can be 100 nm; the third dielectric layer 203 can be Ta2O5, and the thickness can be 126 nm; the first metal layer 204 can be Ag, and the thickness can be 10 nm; the phase change layer 205 uses the phase change material AgInSbTe, and the thickness can be 12 nm; the second dielectric layer 206 can be Ta2O5, and the thickness can be 32 nm; the first dielectric layer 207 can be MgF2, and the thickness can be 233 nm.

[0077] As Figure 3 shown, in the schematic diagram of the display device that generates green, the substrate 301 can be silicon, glass, or a flexible substrate; the second metal layer 302 can be Ag, and the thickness can be 100 nm; the third dielectric layer 303 can be Ta2O5, and the thickness can be 90 nm; the first metal layer 304 can be Ag, and the thickness can be 12 nm; the phase change layer 305 uses the phase change material AgInSbTe, and the thickness can be 12 nm; the second dielectric layer 306 can be Ta2O5, and the thickness can be 10 nm; the first dielectric layer 307 can be MgF2, and the thickness can be 135 nm.

[0078] As Figure 4 shown, in the schematic diagram of the display device that generates green, the substrate 401 can be silicon, glass, or a flexible substrate; the second metal layer 402 can be Ag, and the thickness can be 100 nm; the third dielectric layer 403 can be Ta2O5, and the thickness can be 65 nm; the first metal layer 404 can be Ag, and the thickness can be 13 nm; the phase change material used in the phase change layer 405 can be AgInSbTe, and the thickness can be 10 nm; the second dielectric layer 406 can be Ta2O5, and the thickness can be 20 nm; the first dielectric layer 407 can be MgF2, and the thickness can be 135 nm.

[0079] Figure 5 is Figure 2 the red spectral diagram generated by the corresponding structure, with a reflectivity of up to more than 90%. Figure 6 is Figure 3 the green spectral diagram generated by the corresponding structure, with a reflectivity of up to more than 90%. Figure 7 is Figure 4 the blue spectral diagram generated by the corresponding structure, with a reflectivity of up to more than 90%.

[0080] Figure 8 is Figure 2 the red angle-insensitive diagram generated by the corresponding structure, with an angle insensitivity of up to more than 70 degrees. Figure 9 is Figure 3 the green angle-insensitive diagram generated by the corresponding structure, with an angle insensitivity of up to more than 70 degrees. Figure 10 is Figure 4 the blue angle-insensitive diagram generated by the corresponding structure, with an angle insensitivity of up to more than 65 degrees.

[0081] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A display device, characterized in that, Comprising: An anti-reflection layer including a multi-layer dielectric having a refractive index gradient, where the refractive index of the multi-layer dielectric gradually increases from top to bottom, the K value of the multi-layer dielectric is less than a first preset threshold, and the total thickness and equivalent refractive index of the anti-reflection layer satisfy certain conditions for the three primary colors of red, green, and blue, such that the upper and lower electric fields at the position of the phase change layer below the anti-reflection layer are 0; The phase change layer, where the optical loss of the phase change material used in the phase change layer is greater than a second preset threshold and the refractive index is greater than a third preset threshold, the N value of the phase change material is greater than 1 in the visible light region and the K value is greater than 1 in the visible light region, and the phase change layer is located below the anti-reflection layer; A dielectric layer located below the phase change layer; A metal layer for forming an FP cavity; The dielectric layer below the phase change layer is the third dielectric layer, the metal layer includes a first metal layer and a second metal layer, the first metal layer is located between the third dielectric layer and the phase change layer, the second metal layer is located below the third dielectric layer and serves as a reflective layer, and a substrate is further included below the second metal layer; When the color generated by the display device is red or blue, the total thickness of the anti-reflection layer is λ0 / (4n); When the color generated by the display device 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), where λ c is the target wavelength for generating color in the display device, and n1 is the refractive index of the dielectric layer; The thickness of the phase change material is less than λ c / (4n2π), where λ c is the target wavelength for the display device to generate color, and n2 is the refractive index of the phase change material.

2. The display device according to claim 1, characterized in that, The phase change layer is one or more layers, and each layer of the phase change layer includes a phase change material and an electrode layer deposited on the lower side of the phase change material, and the voltage thresholds of the phase change materials in each layer of the phase change layer are different.

3. The display device according to claim 1 or 2, characterized in that, The phase change material is an alloy compound composed of elements from the sixth main group and elements from the third to fifth main groups, and the alloy compound is doped with elements from the first main group of Ib.

4. The display device according to claim 3, wherein The phase change material includes AgInSbTe and / or InSbTe, and the percentage of each atom in the phase change material is adjustable.

5. The display device according to claim 1 or 2, characterized in that, The dielectric layer includes a dielectric with an optical loss less than a fourth preset threshold.

6. The display device according to claim 1 or 2, characterized in that, The metal layer is a single element formed by one element from the third to fifth main groups or a compound composed of multiple elements.

7. The display device according to claim 1 or 2, characterized in that, The thickness of the metal layer at the bottom serving as the reflective layer in the metal layer is greater than 50 nm.

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