Disclosure of Invention
The embodiment of the invention provides a light-emitting element and a display device, which are used for improving the light-emitting efficiency of the light-emitting element.
An embodiment of the present invention provides a light emitting element including:
a substrate base;
a plurality of light emitting units located on the substrate base plate;
the metal reflecting structure is positioned at one side of the light-emitting unit, which is far away from the substrate, and is provided with a plurality of first hollow structures, the orthographic projection of the light-emitting unit on the substrate is positioned in the orthographic projection range of the first hollow structure on the substrate, and the side wall of the first hollow structure is obliquely arranged relative to the light-emitting surface of the light-emitting unit;
The retaining wall structure is positioned at one side of the metal reflecting structure, which is away from the substrate, and is provided with a plurality of sub-pixel openings, the first hollowed-out structures are in one-to-one correspondence with the sub-pixel openings, and the orthographic projection of the first hollowed-out structures on the substrate is positioned in the orthographic projection range of the sub-pixel openings on the substrate;
And the quantum dot color conversion films are arranged in at least part of the sub-pixel openings.
Optionally, in the light emitting element provided by the embodiment of the present invention, the light emitting element further includes a connection layer located between the metal reflection structure and the retaining wall structure, and the connection layer fills the first hollow structure.
Optionally, in the light emitting element provided in the embodiment of the present invention, the metal reflection structure includes a plurality of reflection portions that are independently disposed around each of the light emitting units, the reflection portions have the first hollowed-out structure, and the connection layer further fills a gap between adjacent reflection portions.
Alternatively, in the light emitting element provided by the embodiment of the invention, the reflecting portion includes a body and a reflecting layer located between the body and the connection layer, the material of the body includes a resin, and the material of the reflecting layer includes ITO/Ag/ITO.
Optionally, in the light emitting element provided in the embodiment of the present invention, a cross-sectional shape of the body along a thickness direction of the substrate is a triangle, and an inner angle of the triangle pointing to the light emitting unit is an acute angle.
Optionally, in the light emitting element provided in the embodiment of the present invention, a sum of angles of the internal angle and an emission angle of the light emitting unit is less than 90 °.
Optionally, in the light emitting element provided by the embodiment of the invention, the light emitting element further includes a metal wire grid polarizer located at a side of the plurality of quantum dot color conversion films, which is away from the substrate, the metal wire grid polarizer includes a cover plate and a metal wire grid located at a side of the cover plate, which is away from the substrate, and the metal wire grid includes a plurality of metal wires arranged in parallel and at intervals.
Optionally, in the light emitting element provided by the embodiment of the present invention, the period of the metal wire grid is less than or equal to 120nm, the height of the metal wire is greater than or equal to 140nm, and the duty ratio of the metal wire grid is 0.35-0.5.
Optionally, in the light emitting element provided by the embodiment of the invention, the light emitting element further includes a metal bonding layer located between the connection layer and the retaining wall structure, wherein the metal bonding layer has a plurality of second hollow structures and metal bonding portions located between adjacent second hollow structures, and orthographic projection of the metal bonding portions on the substrate coincides with orthographic projection of the retaining wall structure on the substrate.
Alternatively, in the light emitting element provided In the embodiment of the present invention, the metal bonding portion includes a first Cu layer, an In layer, and a second Cu layer that are stacked.
Optionally, in the light emitting element provided by the embodiment of the present invention, the thicknesses of the first Cu layer and the second Cu layer are the same, and a ratio of the thickness of the first Cu layer to the thickness of the In layer is greater than 1.2:1.
Optionally, in the light emitting device provided by the embodiment of the present invention, the light emitting device further includes a flat layer filling the second hollow structure.
Optionally, in the light emitting element provided by the embodiment of the present invention, the light emitting element further includes a quantum dot packaging layer located between the metal bonding layer and the retaining wall structure, and the quantum dot packaging layer orthographically projects on the substrate to cover the substrate.
Optionally, in the light emitting element provided in the embodiment of the present invention, a material of the wall structure is a reflective material.
Optionally, in the light emitting element provided by the embodiment of the present invention, the light emitting color of the light emitting unit is blue, the sub-pixel opening includes a first sub-pixel opening, a second sub-pixel opening, and a third sub-pixel opening, the first sub-pixel opening is provided with the red quantum dot color conversion film, the second sub-pixel opening is provided with the green quantum dot color conversion film, and the third sub-pixel opening is filled with a resin material, and the resin material is provided with scattering particles therein.
Optionally, in the light emitting element provided by the embodiment of the present invention, the light emitting element further includes a light shielding layer and a color film layer located between the retaining wall structure and the cover plate, the light shielding layer has a plurality of through holes corresponding to the sub-pixel openings one by one, the color film layer includes a plurality of color resistors, and the color resistors and the quantum dot color conversion film are corresponding one by one and are located in the through holes respectively.
Optionally, in the light emitting element provided in the embodiment of the present invention, the light emitting unit includes a Mini LED or a Micro LED.
Correspondingly, the embodiment of the invention also provides a display device which comprises the light-emitting element provided by the embodiment of the invention.
The embodiment of the invention has the following beneficial effects:
according to the light-emitting element and the display device provided by the embodiment of the invention, the metal reflection structure is arranged between the retaining wall structure and the light-emitting unit, and the side wall (reflection surface) of the first hollow structure of the metal reflection structure is obliquely arranged relative to the light-emitting surface of the light-emitting unit, so that when divergent light rays emitted by the light-emitting unit are incident on the side wall (reflection surface) of the first hollow structure, more light rays can be emitted to the quantum dot color conversion film by the side wall (reflection surface) of the first hollow structure, the light utilization rate is greatly improved, and the light-emitting element with high light efficiency is obtained.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. It will be apparent that the described embodiments are some, but not all, of the embodiments of the present disclosure. And embodiments of the disclosure and features of embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without the need for inventive faculty, are within the scope of the present disclosure, based on the described embodiments of the present disclosure.
Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of the terms "comprising" or "includes" and the like in this disclosure is intended to cover an element or article listed after that term and equivalents thereof without precluding other elements or articles. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "inner", "outer", "upper", "lower", etc. are used merely to denote relative positional relationships, which may also change accordingly when the absolute position of the object to be described changes.
It should be noted that the dimensions and shapes of the various figures in the drawings do not reflect true proportions, and are intended to illustrate the present disclosure only. And the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
An embodiment of the present invention provides a light emitting element, as shown in fig. 1, including:
A substrate 1;
a plurality of light emitting units 2 on the substrate 1;
The metal reflection structure 3 is positioned at one side of the light-emitting unit 2, which is far away from the substrate 1, and the metal reflection structure 3 is provided with a plurality of first hollowed-out structures 301, the orthographic projection of the light-emitting unit 2 on the substrate 1 is positioned in the orthographic projection range of the first hollowed-out structures 301 on the substrate 1, and the side wall 31 (reflection surface) of the first hollowed-out structures 301 is obliquely arranged relative to the light-emitting surface 21 of the light-emitting unit 2;
The retaining wall structure 4 is positioned at one side of the metal reflecting structure 3, which is away from the substrate 1, the retaining wall structure 4 is provided with a plurality of sub-pixel openings (41, 42 and 43), the first hollowed-out structures 301 are in one-to-one correspondence with the sub-pixel openings (41, 42 and 43), and the orthographic projection of the first hollowed-out structures 301 on the substrate 1 is positioned in the orthographic projection range of the corresponding sub-pixel openings (41, 42 and 43) on the substrate 1;
a plurality of quantum dot color conversion films 5, wherein the quantum dot color conversion films 5 are disposed within at least part of the sub-pixel openings (e.g., 41 and 42).
According to the light-emitting element provided by the embodiment of the invention, the metal reflection structure is arranged between the retaining wall structure and the light-emitting unit, and the side wall (reflection surface) of the first hollow structure of the metal reflection structure is obliquely arranged relative to the light-emitting surface of the light-emitting unit, so that when divergent light rays emitted by the light-emitting unit are incident to the side wall (reflection surface) of the first hollow structure, more light rays can be emitted to the quantum dot color conversion film by the side wall (reflection surface) of the first hollow structure, the light utilization rate is greatly improved, and the light-emitting element with high light efficiency is obtained.
In a specific implementation, in the light emitting device provided by the embodiment of the present invention, as shown in fig. 1, the light emitting device further includes a connection layer 6 located between the metal reflective structure 3 and the retaining wall structure 4, where the connection layer 6 fills the first hollow structure 301. Specifically, the material of the connection layer 6 may be GaN.
In a specific implementation, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1, the metal reflective structure 3 may include a plurality of reflective portions 32 that are independently disposed around each light emitting unit 2, where the reflective portions 32 have a first hollowed-out structure 301, and the connection layer 6 further fills gaps between adjacent reflective portions 32, so as to ensure flatness of subsequent film layers.
In particular, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1, the entire reflecting portion 32 may be made of a reflective metal material, such as Ag, al, mo, or the like.
In particular, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 2, the reflective portion 32 may include a body 321 and a reflective layer 322 located between the body 321 and the connection layer 6, the material of the body 321 may include a resin, and the material of the reflective layer 322 may be ITO/Ag/ITO, ITO/Al/ITO, ITO/Mo/ITO, or the like.
In a specific implementation, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 2, the cross-sectional shape of the body 321 along the thickness direction of the substrate 1 may be a triangle, where the inner angle β pointing to the light emitting unit 2 is an acute angle, so as to ensure that the reflecting layer 322 is an inclined plane, so that the light emitted by the light emitting unit 2 is reflected to the quantum dot color conversion film 5 when entering the reflecting layer 322, thereby improving the light utilization rate.
Note that fig. 2 of the embodiment of the present invention is an example in which the cross-sectional shape of the body 321 along the thickness direction of the substrate 1 is triangular, and of course, the present invention is not limited thereto, and it is only necessary to ensure that the reflective layer 322 is disposed obliquely with respect to the light emitting surface of the light emitting unit 2.
In a specific implementation, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1 and fig. 2, the metal reflection structure 3 is exemplified by including a plurality of reflection portions 32 that are independently disposed around each light emitting unit 2, and of course, the metal reflection structure 3 may also be a grid-like structure, and as shown in fig. 3, the first hollow structure 301 is a mesh of the grid-like structure, and a side wall (reflection surface) of the mesh is disposed obliquely with respect to the light emitting surface of the light emitting unit 2.
It should be noted that, the metal reflective structure 3 in fig. 3 may be made of a reflective metal material, or may be a body made of a resin material, where the body has a first hollow structure, and then a reflective layer is formed on a sidewall of the first hollow structure of the body.
In a specific implementation, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1,2 and 3, the light emitting element further includes a metal wire grid polarizer 7 (Wire Grip Polarizer, WGP) located on a side of the plurality of quantum dot color conversion films 5 facing away from the substrate 1, where the metal wire grid polarizer 7 includes a cover plate 71 and a metal wire grid 72 located on a side of the cover plate 71 facing away from the substrate 1, and the metal wire grid 72 includes a plurality of metal wires 721 arranged in parallel and spaced apart. Specifically, when the light emitted from the light emitting unit 2 is incident on the wire grid polarizer 7, the incident light can be decomposed into light having a vibration direction parallel to the transmission direction (TM light perpendicular to the wire) and light having a vibration direction perpendicular to the transmission direction (TE light parallel to the wire), the TM wave exits, and the TE wave is reflected below the cover plate 71. For example, the TE wave is reflected to the inclined plane of the quantum dot color conversion film 5 or the metal reflection structure 3 to become secondary excitation light, so that the light utilization rate is greatly improved, and high light efficiency is obtained.
Specifically, the cover plate 71 may be a glass substrate.
In a specific implementation, in the light emitting element provided by the embodiment of the present invention, as shown in fig. 1,2 and 3, the light emitting element further includes a metal bonding layer 8 located between the connection layer 6 and the retaining wall structure 4, where the metal bonding layer 8 has a plurality of second hollow structures 801 and metal bonding portions 81 located between adjacent second hollow structures 801, and an orthographic projection of the metal bonding portions 81 on the substrate 1 coincides with an orthographic projection of the retaining wall structure 4 on the substrate 1. Specifically, the metal bonding layer 8 serves as a reflecting layer, for example, when the light reflected from the metal wire grid polarizer 7 is incident on the metal bonding layer 8, the metal bonding layer 8 can reflect the light to the quantum dot color conversion film 5 for excitation, so that more excitation light is further obtained, and the luminous efficiency is improved.
In particular, in the light emitting element provided In the embodiment of the present invention, as shown In fig. 1, 2 and 3, the metal bonding portion 81 may include a first Cu layer 811, an In layer 812 and a second Cu layer 813 that are stacked. Specifically, the first Cu layer 811 and the second Cu layer 813 mainly function to reflect and connect upper and lower film layers, and the In layer 812 mainly functions to connect the first Cu layer 811 and the second Cu layer 813.
In a specific implementation, in the light emitting device provided In the embodiment of the present invention, as shown In fig. 1, 2 and 3, the thicknesses of the first Cu layer 811 and the second Cu layer 813 may be the same, and the ratio of the thickness of the first Cu layer 811 to the thickness of the In layer 812 may be greater than 1.2:1, so that the first Cu layer 811 and the second Cu layer 813 have larger reflection surfaces, and the light utilization efficiency is further improved.
In a specific implementation, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 1, 2 and 3, the light emitting device further includes a flat layer 9 filled with the second hollow structure 801, where the thickness of the flat layer 9 is the same as that of the metal bonding portion 81, and the material of the flat layer 9 may be resin.
In a specific implementation, in the light emitting element provided by the embodiment of the present invention, as shown in fig. 1, fig. 2 and fig. 3, the light emitting element further includes a quantum dot packaging layer 10 located between the metal bonding layer 8 and the retaining wall structure 4, where the quantum dot packaging layer 10 is projected on the substrate 1 to cover the substrate 1, and the quantum dot packaging layer 10 is used to block external water vapor, and protect the quantum dot material in the quantum dot color conversion film 5 from contacting with water, oxygen, and so on, so as to improve stability and lifetime of the device. Specifically, the material of the quantum dot encapsulation layer 10 may be SiON.
In practical implementation, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 2 and 4, fig. 4 is a schematic partial structure diagram of fig. 2, and the sum of the angle of the internal angle β and the light emitting angle α of the light emitting unit 2 is smaller than 90 °. Specifically, the light emitting angle α of the light emitting unit 2 refers to an angle between the light emitted by the light emitting unit 2 and the normal L perpendicular to the light emitting unit 2, and at this time, the light emitted by the light emitting unit 2 and larger than the angle α is reflected by the reflecting layer 322 and can enter the quantum dot color conversion film 5 for excitation, so as to obtain more excitation light.
As shown in fig. 4, the area of the light emitting unit 2 is S1, the area of the quantum dot color conversion film 5 is S2, the angular spectrum of the light emitting angle α of the light emitting unit 2 is from-90 ° to +90°, and how much angle of light enters the quantum dot color conversion film 5 is determined according to the area of the light emitting unit 2 being S1 and the area of the quantum dot color conversion film 5 being S2, and the height (e.g., 10.32 μm) of the intermediate film layers (the connection layer 6, the flat layer 9, and the quantum dot encapsulation layer 10). In the metal bonding layer 8, for example, the thickness of the first Cu layer and the second Cu layer is 2 μm, the thickness of the In layer is 1.32 μm, that is, the thickness of the metal bonding layer 8 is 5.32 μm, the thickness of the connection layer 6 is 4 μm, the thickness of the quantum dot encapsulation layer 10 is 1 μm, and the thickness of the planarization layer 9 and the thickness of the metal bonding layer 8 are the same. When s2=50 μm×50 μm, s1=20 μm×20 μm, the light emission angle α= ±56.3° incident on the quantum dot color conversion film 5 is as large as possible, so that more light emitted from the light emitting unit 2 enters the quantum dot color conversion film 5, and the light utilization efficiency is improved.
In practical implementation, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 2 and 4, since the cross-sectional shape of the body 321 of the reflecting portion 32 along the thickness direction of the substrate 1 is a triangle, the internal angle β pointing to the light emitting unit 2 in the triangle is an acute angle, and the sum of the angle β and the angle α of the light emitting unit 2 is smaller than 90 °, it is assumed that the light emitting angle α=56.3°, that is, β <90 ° - α is required, at this time, the light emitted by the light emitting unit 2 and larger than the angle α is reflected by the reflecting layer 322, and can enter the quantum dot color conversion film 5 to be excited, so as to obtain much excitation light.
In a specific implementation, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1, 2 and 3, the material of the retaining wall structure 4 may be a reflective material. Therefore, when the light emitted by the light emitting unit 2 is incident to the retaining wall structure 4, the light can be reflected back, on one hand, the light can be prevented from penetrating through the retaining wall structure 4 and entering the adjacent sub-pixel openings, so that the problem of light crosstalk is further avoided, and on the other hand, the light incident to the retaining wall structure 4 can be reflected back, and the effect of enhancing the light emission can be realized on the basis of avoiding the light crosstalk.
Alternatively, the material of the retaining wall structure 4 may be KW-8826 (high acid value resin) which may have a reflectivity of 56% for 550nm light.
As shown in fig. 5, fig. 5 illustrates several possible reflection paths of the light emitted by the light emitting unit 2 and incident to the metal wire grid polarizer 7 by taking one light emitting unit 2 in the structure shown in fig. 1 as an example, TM waves are emitted, the TE waves may be reflected to the quantum dot color conversion film 5, the inclined plane of the metal reflecting structure 3 or the first Cu layer and the second Cu layer of the metal bonding layer 8, and become secondary excitation light, so that the light utilization rate is greatly improved, and high light efficiency is obtained, wherein the path A1 is that the TE waves are reflected to the quantum dots in the quantum dot color conversion film 5 and then excite the quantum dots again to emit light, the path A2 is that the TE waves are reflected to the Cu layer of the metal bonding layer 8 and then reflected to the retaining wall structure 4, the incident light is reflected to the quantum dot color conversion film 5 again to excite the quantum dots to emit light, the path A3 is reflected to the inclined plane of the retaining wall structure 3, and the light utilization rate of the metal reflecting structure 3 is greatly improved, and the light utilization rate of the three-level quantum dots is greatly improved due to the fact that the light is reflected to the three-level quantum dot color conversion film is excited again arranged, so that the light can be more excited by the quantum dots of the light reflection film. Therefore, the embodiment of the invention can obtain the light-emitting element with high light efficiency through the mutual matching of the metal wire grid polarizer 7, the inclined plane of the metal reflecting structure 3 and the metal bonding layer 8.
In the following, the recycling of light is described in detail by the reflection path A1 shown in fig. 5, as shown in fig. 6A-6C, fig. 6A is a transmission metal wire grid polarization schematic diagram, fig. 6B is a plan schematic diagram of WGP, fig. 6C is a reflection path A1 of TE wave, it can be seen that the polarization direction is perpendicular to the plane of the paper (TE wave) and encounters a quantum dot in the quantum dot color conversion film (for example, light propagates downwards and other directions downwards), because the reflection surface is a sphere, the polarization state of the reflected light is no longer perpendicular to the plane of the paper, but forms an included angle with the plane of the paper, a component exists in the TM wave direction, and when the WGP is encountered, as shown in fig. 6D and 6E, fig. 6D and 6E are top views of two reflected lights, only TE waves in abcd are still polarized states of TE wave in four directions, and the polarization states of the light emitted in other directions are all changed, for example, fig. 6D is TE wave reflected and incident to the WGP is 30 ° emitted in D direction, and the original TE wave is assumed to be 1, and the new light is emitted in the direction of TE wave 30 ° s1=0.866, The tm wave direction component is cos60 °1=0.5, Where 0.5 component of light passing through the WGP can be emitted, FIG. 6E shows that the light incident on the WGP after reflection of TE wave is emitted at 45 deg. from d direction, assuming that the original TE wave is 1, the new emitted light has a cos45 deg. component in TE wave direction1=0.707, The tm wave direction component is cos45 °1=0.707, At which point there is a component ray of 0.707 that can exit through the WGP.
In the following, the recycling of light by the reflection path A2 shown in fig. 5 will be described in detail, and as shown in fig. 5, 7A and 7B, fig. 7A is a schematic plan view of the reflection path A2 in fig. 5, it can be seen that only the polarization states of light emitted in four directions abcd are TE waves, the polarization states of light emitted in other directions are changed, if the TE waves are reflected and then incident into WGP, the light is emitted in the d direction θ°, and if the original TE wave is 1, the new emitted light is in the TE wave direction with the component cos θ°The 1, TM wave direction component is sin theta DEG1, At this time, there is a component light ray of sin θ° passing through the WGP.
Note that, the reflection path A3 in fig. 5 is similar to the reflection path A2, and will not be described in detail.
Therefore, the light-emitting element provided by the embodiment of the invention can obtain a light-emitting element with high light efficiency through the mutual matching of the metal wire grid polarizer 7, the inclined plane of the metal reflecting structure 3 and the metal bonding layer 8.
In particular, in the light emitting element provided in the embodiment of the present invention, as shown in fig. 1,2 and 3, the light emitting color of the light emitting unit 2 may be blue, that is, the light emitting unit 2 is a blue light source, and blue light is used as excitation light, so that the excitation effect is better, where the sub-pixel openings include a first sub-pixel opening 41, a second sub-pixel opening 42 and a third sub-pixel opening 43, where the first sub-pixel opening 41 is provided with a red quantum dot color conversion film 5 (R-QD), the second sub-pixel opening 42 is provided with a green quantum dot color conversion film 5 (G-QD), the third sub-pixel opening 43 is filled with a resin material 11, and the resin material 11 has scattering particles (not shown). Specifically, the third sub-pixel opening 43 may directly emit blue light as a blue sub-pixel, the red quantum dots in the red quantum dot color conversion film 5 (R-QD) in the first sub-pixel opening 41 may convert blue light into red light after being excited by blue light and become red sub-pixels, the green quantum dots in the green quantum dot color conversion film 5 (G-QD) in the second sub-pixel opening 42 may convert blue light into green light after being excited by blue light and become green sub-pixels, wherein the red quantum dot color conversion film 5 (R-QD), the green quantum dot color conversion film 5 (G-QD) and the resin material 11 may be sequentially arranged to form three primary sub-pixels, and the three primary sub-pixels form pixel units and are circularly and repeatedly arranged to form a matrix distribution so as to realize a color display function.
Specifically, in the third sub-pixel opening 43, by doping the scattering particles in the resin material 11, and then filling up the depressions of the third sub-pixel opening 43 with the resin material 11 doped with the scattering particles, and the scattering particles can enhance the light-emitting effect and increase the light emission viewing angle. Alternatively, the material of the scattering particles may be TiO2.
In particular, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 1, 2 and 3, the light emitting device further includes a light shielding layer 12 and a color film layer 13 between the retaining wall structure 4 and the cover plate 71, the light shielding layer 12 has a plurality of through holes corresponding to the sub-pixel openings (41, 42 and 43) one by one, and the color film layer 13 includes a plurality of color resists (R-CF, G-CF and B-CF), where the color resists (R-CF, G-CF and B-CF) correspond to the quantum dot color conversion films 5 one by one and are located in the through holes respectively. For example, the red quantum dot color conversion film (R-QD) corresponds to the red color group (R-CF), the green quantum dot color conversion film (G-QD) corresponds to the green color group (G-CF), and the third sub-pixel opening 23 (filled with a resin material) corresponds to the blue color group (B-CF). The color resistor can play a role in filtering, so that light with higher color purity is emitted from each sub-pixel opening, and the display effect is improved.
Specifically, the substrate in the embodiment of the present invention may be a driving back plate, and when the light emitting unit 2 emits light, a driving current is input to the light emitting unit 2 through the driving back plate, and the specific light emitting principle is the same as that of the prior art, and will not be described in detail herein.
Alternatively, the light emitting unit may be a Micro LED, and the pixel resolution of the light emitting element may be improved due to the small size of the Micro LED. In particular, micro LEDs are typically less than 100 μm in size. Of course, the light emitting unit may be any other light emitting unit such as Mini LED, which is not limited in the present invention. Specifically, when the light emitting unit is a Mini LED, the size of the Mini LED is 100 μm to 200 μm.
In specific implementation, the light-emitting element provided by the embodiment of the invention can be used as a backlight source of a display device, for example, as a backlight source of a liquid crystal display device, so that the light-emitting efficiency can be improved, and the power consumption can be reduced.
As shown in fig. 8, fig. 8 is a schematic plan view of three sub-pixel openings corresponding to fig. 1, fig. 2 and fig. 3, where the structure shown in fig. 8 may be used as a repeated light emitting unit, when the light emitting element provided in the embodiment of the present invention is used as a backlight source of a display device, the structure of the backlight source is shown in fig. 9, and fig. 9 is a repeated arrangement of a plurality of structures shown in fig. 8, and when the light emitting element provided in the embodiment of the present invention is directly used as a pixel structure of the display device to display, the structure shown in fig. 8 is used as a pixel unit (that is, includes R, G, B sub-pixels).
In order to obtain the maximum luminance conversion ratio to further increase the light emission efficiency of the light emitting element, as shown in fig. 10A and 10B, fig. 10A and 10B are luminance conversion diagrams corresponding to the film thickness variation of the red quantum dot color conversion film and the green quantum dot color conversion film, respectively, and it is found that the maximum luminance conversion ratio can be obtained when the film thicknesses of the red quantum dot color conversion film and the green quantum dot color conversion film both reach 20 μm. Therefore, the film thickness of the red quantum dot color conversion film and the green quantum dot color conversion film in the embodiment of the present invention is preferably more than 20 μm.
Specifically, as shown in fig. 11A, fig. 11A is a schematic structural diagram of the metal wire grid polarizer 7 (WGP) in fig. 1-3, the wire grid period d of the metal wire grid 72 is in the range of 0-400 nm, the width a of the metal wire 721 is in the range of 0-200 nm, the height H of the metal wire 721 is greater than 100nm, the duty ratio a/d of the metal wire grid 72 is in the range of 0-0.5, the extinction ratio of the metal wire grid 72 is the ratio of the transmittance of TM wave to TE wave (TTM/TTE), the height H of the metal wire 721 has an influence on the extinction ratio, and the extinction ratio is higher as the H value is larger. As shown in fig. 11B to 11E, the influence of each parameter in the metal wire grid polarizer 7 on the performance of the light emitting element is analyzed, as shown in fig. 11B, the extinction ratio increases with the decrease of the period D in the visible light band, as shown in fig. 11C, the transmittance of TM wave decreases with the increase of the duty ratio a/D, and the extinction ratio increases, so that the duty ratio needs to be determined as required for the fixed wire grid period D, as shown in fig. 11D, the TM transmittance increases after decreasing and the overall decrease trend, and the TE wave transmittance decreases sharply, so that the extinction ratio increases sharply, as shown in fig. 11E, fig. 11E is a schematic diagram of the relationship between the wire grid period D of the metal wire grid and the height H of the metal wire 721 and the polarization PE ((TTM-TTE)/(TTM+TTE)) of the metal wire grid polarizer 7, as shown in fig. 11C, the PE increases with the decrease of the duty cycle D, the PE increases with the increase of the height H of the metal wire grid 721, so that the metal wire grid polarizer 7 can increase as required, and the overall utilization of the WGP is guaranteed, and the total transmittance of the wire grid p is considered to be equal to or more than 120nm when the total polarization ratio of the wire grid p is equal to or less than or equal to the maximum. For example, when d=120 nm, pe=99.94% to 99.96%, t=36 to 40%. In order to further increase the transmittance, the duty ratio a/d of WGP is required to be reduced, as shown in fig. 12, when a/d=55/121 nm, pe=99.94%, t=36 to 40%. Therefore, in the light emitting device provided in the embodiment of the present invention, as shown in fig. 11A, the wire grid period d of the metal wire grid polarizer 7 is less than or equal to 120nm, the height of the metal wire 721 is greater than or equal to 140nm, and the duty ratio of the metal wire grid polarizer 7 is 0.35 to 0.5.
Specifically, the material of the metal wires 721 of the metal wire grid polarizer 7 may be Al, ag, au, cu, gr, preferably, the material of the metal wires 721 is Al, and when the metal wire grid is made of Al, the TM transmittance is high and the extinction ratio is high.
Referring to fig. 1 for example, a specific structure of a light emitting unit 2 provided in an embodiment of the present invention is illustrated in fig. 13, fig. 13 is a schematic structural diagram of a metal reflective structure 3, a connection layer 6 and the light emitting unit 2 fabricated on a sapphire substrate 100, the light emitting unit 2 includes a quantum well layer 201, a P-type semiconductor layer 202, a P-electrode 203 (e.g. ITO), an N-electrode 204 (e.g. metal material), a P-type pad 205 and an N-type pad 206, wherein the P-type pad 205 is electrically connected to the P-electrode 203 through a via penetrating through an insulating layer 207, and the N-type pad 206 is electrically connected to the N-electrode 204 through a via penetrating through the insulating layer 207.
The following describes in detail a method for manufacturing a light emitting element according to an embodiment of the present invention, taking the light emitting element shown in fig. 1 as an example:
(1) Forming a light shielding layer 12 and a color film layer 13 (R-CF, B-CF, G-CF) on a glass substrate 71', as shown in FIG. 14A;
(2) Forming a retaining wall structure 4 on the basis of fig. 14A, the retaining wall structure having a plurality of sub-pixel openings (41, 42, 43), as shown in fig. 14B;
(3) The quantum dot color conversion film 5 (R-QD, G-QD) and the resin material 11 are formed in each sub-pixel opening (41, 42, 43) of fig. 14B, as shown in fig. 14C.
(4) Forming a quantum dot encapsulation layer 10 on the basis of fig. 14C, as shown in fig. 14D;
(5) The metal reflective structure 3 and the connection layer 6 are formed on the sapphire substrate 100 as shown in fig. 14E, the metal reflective structure 3 may be formed by a step exposure process, and GaN is coated once after each step exposure process to form the connection layer 6;
(6) Forming the light emitting unit 2 on the basis of fig. 14E as shown in fig. 14F, the specific structure of the light emitting unit 2 being shown in fig. 13;
(7) In fig. 14F, an adhesive layer 200, a release layer 300, and a temporary carrier 400 are sequentially formed on a side of the light emitting unit 2 facing away from the sapphire substrate 100, as shown in fig. 14G;
(8) The sapphire substrate 100 in fig. 14G is peeled off as shown in fig. 14H;
(9) The metal bonding layer 8 and the planarization layer 9 are formed on the basis of fig. 14H, as shown in fig. 14I.
(10) Binding the structural pairs shown in fig. 14D and 14I, as shown in fig. 14J;
(11) As shown in fig. 14K, the adhesive layer 200, the release layer 300, and the temporary carrier 400 in fig. 14J are removed, as shown in fig. 14L;
(12) Thinning the glass substrate 71' in fig. 14L with HF acid to form a cap plate 71, and forming a metal wire grid 72 on the cap plate 71, as shown in fig. 14M;
(13) The light emitting unit 2 in fig. 14M is bound with the substrate base plate 1 (driving back plate), as shown in fig. 1.
In summary, the light-emitting element shown in fig. 1 provided by the embodiment of the present invention can be prepared through the steps (1) - (13).
Based on the same inventive concept, the embodiment of the present invention also provides a display device, including any one of the light emitting elements provided by the embodiment of the present invention. The display device can be any product or component with display function such as a mobile phone, a tablet personal computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like. Other essential components of the display device will be understood by those skilled in the art, and are not described herein in detail, nor should they be considered as limiting the invention. The implementation of the display device can be referred to the above embodiments of the light emitting element, and the repetition is not repeated.
In a specific implementation, when the display device provided by the embodiment of the present invention is an OLED display device, the light emitting element provided by the embodiment of the present invention may be used as a pixel unit of the OLED display device to emit light.
In a specific implementation, when the display device provided by the embodiment of the invention is an LCD display device, as shown in fig. 15, fig. 15 is a schematic structural diagram of the LCD display device, where the display device includes a liquid crystal display panel and the light emitting element provided by the embodiment of the invention, the liquid crystal display panel includes an array substrate 110 and a color film substrate 120 that are disposed opposite to each other, a liquid crystal layer (not shown) between the array substrate 110 and the color film substrate 120, a first polarizer 130 on a side of the array substrate 110 facing away from the color film substrate 120, and a second polarizer 140 on a side of the color film substrate 120 facing away from the array substrate 110, and the light emitting element 150 provided by the embodiment of the invention is located on a side of the first polarizer 130 facing away from the second polarizer 140, and further includes a diffusion film 160 located between the first polarizer 130 and the light emitting element 150, and a backlight encapsulation layer 170 located between the diffusion film 160 and the light emitting element 150, where an optical distance OD between the diffusion film 160 and the encapsulation layer 170 is 0.2-0.5mm.
Specifically, the light emitting element 150 is assembled with the LCD display panel through the optical distance OD and the diffusion film 160, and the optical distance OD provides a uniform light path to achieve the uniformity requirement, and may also be achieved through the diffusion film 160 (or the optical distance+the diffusion film together).
The display device provided by the embodiment of the invention can be a head-mounted display such as an AR/VR (active matrix/virtual reality) and has high requirement on pixel resolution, and the light emitting element provided by the embodiment of the invention can be in one-to-many correspondence with the pixel units in the LCD display panel, for example, one repeated light emitting unit in FIG. 8 can correspond to nine pixel units (R, G, B) in the display panel.
According to the light-emitting element and the display device provided by the embodiment of the invention, the metal reflection structure is arranged between the retaining wall structure and the light-emitting unit, and the side wall (reflection surface) of the first hollow structure of the metal reflection structure is obliquely arranged relative to the light-emitting surface of the light-emitting unit, so that when divergent light rays emitted by the light-emitting unit are incident on the side wall (reflection surface) of the first hollow structure, more light rays can be emitted to the quantum dot color conversion film by the side wall (reflection surface) of the first hollow structure, the light utilization rate is greatly improved, and the light-emitting element with high light efficiency is obtained.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.