CN116449629A - Pixel structure and display driving method thereof - Google Patents

Abstract

The invention provides a pixel structure and a display driving method thereof, which sequentially comprise the following steps: the first phase change material layer comprises a first metal layer, a first transparent conductive medium layer, a first phase change material layer, a second transparent conductive medium layer, a second phase change material layer, a third transparent conductive medium layer, a second metal layer and a fourth transparent conductive medium layer; the thickness of the first metal layer is within a first preset thickness range and is a total reflection layer; the thickness of the second metal layer is within a second preset thickness range and is a semitransparent reflecting layer; the other layers are used as dielectric materials and form a Fabry-Perot resonant cavity together with the first metal layer and the second metal layer; when the physical thickness of the resonant cavity is at the third preset thickness, the pixel structure is capable of selectively reflecting light of different colors when the crystalline state of either one of the first and second phase change material layers is changed. The invention realizes in-situ switching of multiple reflection colors on a single display pixel, has the characteristic of high pixel density, and can effectively improve the image resolution of the reflection type display device.

Description

A pixel structure and display driving method thereof

technical field

The invention belongs to the field of display technology, and more specifically relates to a pixel structure and a display driving method thereof.

Background technique

With the development of science and technology, display technology has become an indispensable part of people's daily life, and has been widely used in smart phones, tablet computers, TVs, etc. The popularization of display technology also makes people put forward higher and higher requirements for the performance of various displays. At present, people generally pay attention to the resolution, refresh rate, color gamut and eye protection functions of display devices.

The current common color display is based on sub-pixels with three primary colors of red, green and blue to form a display pixel to reproduce color images, but this pixel arrangement is not conducive to the increase of pixel density, and also greatly limits the image resolution in the display. rate increase.

Contents of the invention

In view of the defects of the prior art, the purpose of the present invention is to provide a display structure and a display driving method thereof, aiming to solve the problem that the existing display pixels are composed of multiple sub-pixels, which is not conducive to the increase of pixel density and limits the improvement of display image resolution. .

In order to achieve the above object, in the first aspect, the present invention provides a pixel structure, which includes from bottom to top: a first metal layer, a first transparent conductive medium layer, a first phase change material layer, a second transparent conductive medium layer, The second phase change material layer, the third transparent conductive medium layer, the second metal layer and the fourth transparent conductive medium layer;

The thickness of the first metal layer is within a first preset thickness range, so that the first metal layer is a total reflection layer;

The thickness of the second metal layer is within a second preset thickness range, so that the second metal layer is a translucent reflection layer;

The first transparent conductive medium layer, the first phase change material layer, the second transparent conductive medium layer, the second phase change material layer, the third transparent conductive medium layer and the fourth transparent conductive medium layer are used as dielectric materials, and the first The metal layer and the second metal layer form a Fabry-Perot resonant cavity;

When the physical thickness of the Fabry-Perot resonant cavity is at the third preset thickness, when the crystallization state of any layer in the first phase-change material layer and the second phase-change material layer changes, the pixel structure can be selected Sex reflects light of different colors.

In an optional example, the third preset thickness multiplied by the refractive index of the pixel structure is equal to an integer multiple of the wavelength of light to be selectively reflected by the pixel structure; wherein, the refractive index of the pixel structure varies with the first phase The crystallization state of the phase change material layer and the second phase change material layer changes.

In an optional example, the first preset thickness range is 100nm-150nm;

The second preset thickness range is 5nm-20nm.

In an optional example, the thicknesses of the above two phase-change material layers are both within 70nm-120nm;

The thicknesses of the above four transparent conductive medium layers are all within 50nm-200nm.

In an optional example, the above two phase change material layers are made of chalcogenide phase change materials.

In an optional example, the above four transparent conductive medium layers are made of indium tin oxide or aluminum-doped zinc oxide.

In an optional example, when the physical thickness of the Fabry-Perot resonant cavity is at the third preset thickness, and the first phase-change material layer is GeTe material, and the second phase-change material layer is Sb ₂ S ₃ material , if both the first phase-change material layer and the second phase-change material layer are in the amorphous state, the pixel structure can selectively reflect blue light, and if the first phase-change material layer and the second phase-change material layer are both in the crystal state state, the pixel structure can selectively reflect green light; if the first phase-change material layer is in a crystalline state and the second phase-change material layer is in an amorphous state, the pixel structure can selectively reflect red light.

In a second aspect, the present invention provides a display driving method for the pixel structure provided in the first aspect, comprising the following steps:

Applying electric pulses of different intensities to the pixel structure allows the first phase-change material layer and the second phase-change material layer to crystallize respectively, so as to control the crystallization state of the two phase-change material layers in the pixel structure, so that the pixel structure can be selected Sex reflects light of different colors.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

The present invention provides a pixel structure and a display driving method thereof. The pixel structure is a multi-layer film structure, which includes a substrate layer, a first metal layer, a first transparent conductive medium layer, a first phase-change material layer, and a second phase-change material layer from bottom to top. The transparent conductive medium layer, the second phase change material layer, the third transparent conductive medium layer, the second metal layer, and the fourth transparent conductive medium layer constitute a typical Fabry-Perot resonant cavity. With the help of the bottom metal electrode layer and the top transparent conductive medium layer, the two layers of phase change materials can be crystallized successively by means of electric heating, and various states such as amorphous-amorphous, amorphous-crystalline and crystal-crystalline can be obtained, and have different Optical thickness, so as to selectively reflect different colors of light under the tungsten filament white woven light source. The invention realizes in-situ switching of at least three reflective colors on a single display pixel, has the characteristics of high pixel density, and can effectively improve the image resolution of reflective display devices.

Description of drawings

Fig. 1 is a schematic diagram of pixel arrangement of an electrically controlled in-situ switchable reflective color display pixel provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of the film structure of an electrically controlled in-situ switchable reflective color display pixel provided by an embodiment of the present invention;

Fig. 3 is the reflectance spectrum of the color display pixel simulated by Embodiment 1 of the present invention;

Fig. 4 is the chromaticity diagram of the color display pixel simulated by Embodiment 1 of the present invention;

Fig. 5 is a dispersion curve of the refractive index n and the extinction coefficient k of each material provided by the present invention.

Detailed ways

For the convenience of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are firstly explained and described below.

Embodiments of the present application are described below with reference to the drawings in the embodiments of the present application.

In order to solve the problems of traditional color displays in high-resolution display, the present invention provides an electrically controlled in-situ switchable reflective color display pixel based on phase change materials, which can be applied to ultra-high-resolution passive display devices .

It should be noted that, based on the principle of the Fabry-Perot resonant cavity, it only allows the light of a specific wavelength whose wavelength integer multiple is equal to the optical thickness of the resonant cavity (the product of the film refractive index and the physical thickness) to pass through, thereby having color selectivity, the present invention In principle, the provided pixel structure can selectively reflect light of at least four different colors (crystalline state-crystalline state, crystalline state-amorphous state, amorphous state-crystalline state) as the crystal state of the two phase change material layers changes. state and amorphous state-amorphous state), under this premise, it is first necessary to control the thickness of each film layer under a suitable crystalline state combination to construct a Fabry-Perot resonant cavity and have a color selectivity, and the structure It is possible to have three color selectivity under the combination of the remaining three crystal states.

It can be understood that, based on the analysis of the above principles, the present invention can theoretically realize the selective reflection of multiple colors, and can realize the reflection of the same light by different means through the selection of different phase change materials and the regulation of the thickness of each layer of film. Optionally, under the effect of the above principles, the present invention intends to achieve selective reflection of a certain light and is not limited to one implementation.

Therefore, for those skilled in the art, the schemes of selective reflection of multiple colors of light realized by the specific technical means adopted under the technical principles of the present invention should be covered within the protection scope of the present invention.

Specifically, in order to vividly illustrate the present invention, the present invention is illustrated by taking the selective reflection of three colors of red, green, and blue as examples, and the above illustrations should not be regarded as any substantial limitation on the protection technical solution of the present invention.

The object of the present invention is to provide an electrically controlled and in-situ switchable reflective color display pixel based on a phase change material, which can switch between three different states under the stimulation of electric pulses, and respectively correspond to Under the light source, three colors of red, green and blue are selectively reflected, so that high-resolution color images can be displayed under light.

In order to achieve the above object, the present invention provides an electrically controlled in-situ switchable reflective color display pixel based on a phase change material, which can freely select a color that reflects red, green or blue light under the stimulation of an electric pulse. kind. The display pixel is a multi-layer film structure, and from bottom to top are the first metal reflective layer, the first transparent conductive medium layer, the first phase change material layer, the second transparent conductive medium layer, the second phase change material layer, the third A transparent conductive medium layer, a second metal layer, and a fourth transparent conductive medium layer.

The present invention provides an electrically controlled and in-situ switchable reflective color display pixel based on phase change materials. The reason why it has color selectivity is that the reflective layer is formed by the bottom metal electrode, and the top metal electrode forms a semi-transparent reflector. The middle transparent conductive layer and phase-change material layer are used as dielectric materials to form a typical Fabry-Perot resonant cavity. After the light enters the Fabry-Perot resonant cavity through the top metal electrode layer, it will be reflected back and forth between the bottom metal reflective layer and the top semi-transparent reflective layer, and the Fabry-Perot resonant cavity can only allow integer multiples of the wavelength equal to the optical thickness of the resonant cavity. Specific wavelengths of light pass through, making them color selective. Further, the optical thickness of the Fabry-Perot resonant cavity is changed by changing the optical parameters brought about by switching the phase-change material layer between crystalline and amorphous states, so as to selectively reflect red, green or blue light three times switch between states.

The above-mentioned electronically controlled and in-situ switchable reflective color display pixels are all homogeneous pixels, which are square and arranged according to the rules of rows and columns. The metal reflective layers at the bottom are all connected to a bit line BL, and the transparent conductive layers at the top are all connected to a word line WL. When an electric pulse is applied to the pixel, the phase-change material layer in the pixel will be heated. By applying electric pulses of different intensities, the two phase-change material layers can be crystallized successively, thus presenting amorphous-amorphous, amorphous-crystalline, Crystallization - three states of crystallization.

In an embodiment, the chalcogenide phase change material is made of germanium tellurium, antimony tellurium, germanium antimony tellurium, germanium antimony selenium tellurium, antimony sulfur or antimony selenium alloy material, and the thickness of the chalcogenide phase change material layer is 50nm -120nm.

In an embodiment, the transparent conductive medium material is made of indium tin oxide or aluminum-doped zinc oxide material, and the thickness of the transparent conductive medium layer is 20nm-200nm.

In an embodiment, the metal electrode material is made of silver, platinum or titanium, and the thickness of the metal electrode layer is 5nm-150nm.

As shown in Figure 1, the pixel arrangement of an electrically controlled in-situ switchable reflective color display pixel based on phase change materials provided by the present invention can follow the standard red, green and blue arrangement, but it is different from the traditional display device by Three red, green, and blue sub-pixels constitute a display pixel. The present invention does not have sub-pixels, but each display pixel can selectively display red, green, and blue light.

In this embodiment, as shown in FIG. 2 , all display pixels are homogeneous pixels with a multi-layer film structure. From bottom to top, they are the substrate layer, the first metal electrode, the first transparent conductive medium layer, the first chalcogenide phase change material layer, the second transparent conductive medium layer, the second chalcogenide phase change material layer, the third transparent The conductive medium layer, the second metal electrode, and the fourth transparent conductive medium layer together constitute the Fabry-Perot resonant cavity, which can have three different states of amorphous-amorphous, amorphous-crystalline, and crystallized under electric pulses. As shown in Figure 3 and Figure 4, they respectively correspond to the selective reflection of blue light, red light, and green light under the white weaving light source. Wherein, a represents an amorphous state, and c represents a crystalline state. The pixel structure provided by the present invention can realize the color display function that requires multiple pixels in a traditional display device in the same pixel.

Preferably, in this embodiment, the optional material of the metal electrode is platinum, titanium or silver, the optional material of the transparent conductive medium layer is indium tin oxide or aluminum-doped zinc oxide, and the optional material of the chalcogenide phase change material layer is germanium tellurium , germanium antimony tellurium, antimony sulfur or antimony selenium alloy.

Specifically, the working principle of an electrically controlled and in-situ switchable reflective color display pixel based on phase change materials in this embodiment is as follows: the bottom metal electrode forms a reflective layer, the top metal electrode forms a semi-transparent mirror, and the middle A transparent conductive layer and a phase-change material layer are used as dielectric materials to form a typical Fabry-Perot resonant cavity. After the light enters the Fabry-Perot resonant cavity through the top metal electrode layer, it will be reflected back and forth between the bottom metal reflective layer and the top semi-transparent reflective layer, and the Fabry-Perot resonant cavity can only allow integer multiples of the wavelength equal to the optical thickness of the resonant cavity ( The product of the film's refractive index and physical thickness) passes light of a specific wavelength, thereby having color selectivity. Therefore, the optical thickness of the Fabry-Perot resonator can be tuned to have the desired color selectivity. Here, we design a Fabry-Perot resonance with a double-layer phase change material by taking advantage of the fact that the phase change material has different refractive indices before and after the phase change, that is, the optical thickness can be changed without changing the film thickness. cavity.

Preferably, the first phase-change material layer is selected to be GeTe material, and the second phase-change material layer is selected to be Sb ₂ S ₃ material. When the two layers of phase change _materials are both amorphous, the multilayer film can selectively reflect blue light; when GeTe is crystalline and _Sb2S3 is amorphous, the multilayer film can selectively reflect red light ; When both GeTe and Sb ₂ S ₃ are crystalline, the multilayer film can selectively reflect green light.

It should be noted that those skilled in the art can also choose other formulations and ratios of phase change materials to realize the phase change material layer according to the existing technology, so as to realize the selective reflection of different colors of light. The above examples do not protect the present invention. Specific limitations of the scope.

Preferably, in this embodiment, an electrically controlled in-situ switchable reflective color display pixel based on a phase change material has a thickness of the bottom metal electrode of 100nm-150nm, a thickness of the transparent conductive medium layer of 50nm-200nm, and the phase change material The thickness of the layer is 70nm-120nm, and the thickness of the top metal electrode is 5nm-20nm.

The electronically controlled in-situ switchable reflective color display pixel based on phase change material provided in this embodiment can realize selective reflection of any color of red, green, and blue in a single pixel, and can display It produces clear images with higher resolution and has features such as eye protection.

An electrically controlled in-situ switchable reflective color display pixel based on a phase change material provided by the present invention will be described in detail below in conjunction with specific embodiments.

Example 1

Each pixel in an electrically controlled in-situ switchable reflective color display pixel based on phase change material provided in Example 1 is a homogeneous pixel, and the film layer structure from bottom to top is Ag/ITO/GeTe/ITO/ Sb ₂ S ₃ /ITO/Ag/ITO, wherein the thickness of the ITO is 20nm-200nm, and the thickness of the phase change material layer is 70-120nm.

In Embodiment 1, the specific design of an electrically controlled in-situ switchable reflective color display pixel based on phase change materials is as follows: (1) the metal reflective layer is selected as Ag material, the transparent conductive medium material is selected as ITO, and the first layer The phase-change material is selected as GeTe, and the phase-change material of the second layer is selected as Sb ₂ S ₃ ; (2) the thickness of the metal reflection layer at the bottom of the multilayer film is 135nm, the bottom ITO layer is 75nm, and the first phase-change material layer is 96nm , the middle ITO layer is 163nm, the second phase change material layer is 92nm, the upper ITO layer is 76nm, the top metal layer is 8nm, and the top ITO layer is 39nm; (3) When the two layers of phase change materials are both amorphous, The reflection color is now blue. When the first layer of phase change material is in crystalline state and the second layer of phase change material is in amorphous state, the corresponding color is red. When the two phase-change material layers are both in a crystalline state, the corresponding color is green. The phase transition described above can be achieved by applying electrical pulses. As shown in the figure, the simulation results show that an electrically controlled in-situ switchable reflective color display pixel based on a phase change material provided in this embodiment can freely switch between selectively reflecting red, green and blue colors.

The reflectance data in this embodiment are obtained through calculation by simulation software. As shown in Figure 5, it is the refractive index n and extinction coefficient k of the materials Ag, ITO, GeTe and Sb ₂ S ₃ in the 400nm-700nm visible light band, and then import the optical parameters of the above materials into the simulation software to build a multilayer film structure, this embodiment selects SiO ₂ as the substrate layer during simulation. After obtaining the simulated reflectance data, import the data into the Chromaticity Diagram in the OriginLab software and process it into a CIE chromaticity diagram, where Spectral Power Distribution of Illuminant is selected as A, that is, the light source is tungsten white weaving light.

It should be understood that expressions such as "comprising" and "may include" that may be used in this application indicate the existence of disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operation and components. In the present application, terms such as "comprising" and/or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components or combinations thereof, but shall not be interpreted as referring to one or more other characteristics. , number, operation, constituent elements, components or the existence or addition possibility of their combination are excluded.

The above is only a specific implementation of the application, but the scope of protection of the application is not limited thereto. Anyone familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the application. Should be covered within the protection scope of this application. Therefore, the protection scope of the present application should be determined by the protection scope of the claims.

Claims (8)

1. A pixel structure, characterized in that it comprises, from bottom to top: a first metal layer, a first transparent conductive medium layer, a first phase-change material layer, a second transparent conductive medium layer, a second phase-change material layer, The third transparent conductive medium layer, the second metal layer and the fourth transparent conductive medium layer; The thickness of the first metal layer is within a first preset thickness range, so that the first metal layer is a total reflection layer; The thickness of the second metal layer is within a second preset thickness range, so that the second metal layer is a translucent reflection layer; The first transparent conductive medium layer, the first phase change material layer, the second transparent conductive medium layer, the second phase change material layer, the third transparent conductive medium layer and the fourth transparent conductive medium layer are used as dielectric materials, and the first The metal layer and the second metal layer form a Fabry-Perot resonant cavity; When the physical thickness of the Fabry-Perot resonant cavity is at the third preset thickness, when the crystallization state of any layer in the first phase-change material layer and the second phase-change material layer changes, the pixel structure can be selected Sex reflects light of different colors. 2. The pixel structure according to claim 1, wherein the third preset thickness multiplied by the refractive index of the pixel structure is equal to an integer multiple of the wavelength of light selectively reflected by the pixel structure; wherein the pixel The refractive index of the structure varies with the crystallization state of the first phase change material layer and the second phase change material layer. 3. The pixel structure according to claim 1 or 2, wherein the first preset thickness range is 100nm-150nm; The second preset thickness range is 5nm-20nm. 4. The pixel structure according to claim 1 or 2, wherein the thicknesses of the two phase-change material layers are both within 70nm-120nm; The thicknesses of the above four transparent conductive medium layers are all within 50nm-200nm. 5. The pixel structure according to claim 1 or 2, characterized in that the two phase-change material layers are made of chalcogenide phase-change materials. 6. The pixel structure according to claim 1 or 2, wherein the four transparent conductive medium layers are made of indium tin oxide or aluminum-doped zinc oxide. 7. The pixel structure according to claim 1, wherein when the physical thickness of the Fabry-Perot resonant cavity is at the third preset thickness, and the first phase-change material layer is a GeTe material, the second phase-change material layer When the layer is made of Sb ₂ S ₃ material, if both the first phase-change material layer and the second phase-change material layer are in an amorphous state, the pixel structure can selectively reflect blue light, and if the first phase-change material layer and the second phase-change material layer Both phase-change material layers are in a crystalline state, and the pixel structure can selectively reflect green light; if the first phase-change material layer is in a crystalline state and the second phase-change material layer is in an amorphous state, then the pixel structure can Selectively reflect red light. 8. A display driving method for the pixel structure according to any one of claims 1 to 7, characterized in that it comprises the following steps: Applying electric pulses of different intensities to the pixel structure allows the first phase-change material layer and the second phase-change material layer to crystallize respectively, so as to control the crystallization state of the two phase-change material layers in the pixel structure, so that the pixel structure can be selected Sex reflects light of different colors.