Patent Grant
12336420
This application is the United States national phase of International Patent Application No. PCT/CN2021/096053 filed on May 26, 2021, and claims the priority to the Chinese patent application No. 202010493184.5 filed on Jun. 3, 2020, the disclosures of which are hereby incorporated by reference in their entirety.
This application relates to a light-emitting device and a fabrication method thereof, a display device or lighting device.
Light extraction efficiency refers to a proportion of light entering into air from an inside of a light-emitting device, in total generated light, and is determined by luminescence efficiency of a light-emitting function layer in the light-emitting device and phenomena, such as reflection, total reflection, interference of film layers in the light-emitting device. At present, light extraction efficiency of an organic light-emitting device is about 20%, and the rest of the light is finally consumed in a non-radiation mode, so the light extraction efficiency is still low. Therefore, there is still room for improvement on related arts of light extraction of the light-emitting device.
An objective of the present application is to provide a light-emitting device with high light extraction efficiency.
In an aspect of the present application, there is provided a light-emitting device. The light-emitting device comprises: a substrate; a light-emitting structure layer disposed on one side of the substrate and comprising a light-emitting function layer; a first light extraction layer disposed on a light exit side of the light-emitting function layer, a light exit surface of the first light extraction layer having an irregular brush-like micro-nano structure.
In an example, the light-emitting device further comprises: a second light extraction layer disposed on the light exit surface of the first light extraction layer, wherein a refractive index of the second light extraction layer is different from a refractive index of the first light extraction layer.
In an example, the light-emitting device satisfies at least one of the following conditions: a difference in refractive index between the first light extraction layer and the second light extraction layer being greater than 0.2; the refractive index of the first light extraction layer being greater than the refractive index of the second light extraction layer; a thickness of the second light extraction layer being less than 200 nm; a light exit surface of the second light extraction layer being a flat surface or having the irregular brush-like micro-nano structure; a material of the first light extraction layer comprising at least one of a polymer, an inorganic material or an organic small-molecule; a material of the second light extraction layer comprising at least one of a metal oxide or metal fluoride; or the second light extraction layer containing scattering particles.
In an example, the light-emitting structure layer comprises a cathode, the light-emitting function layer, and an anode, which are stacked, the anode is disposed close to the substrate, and the first light extraction layer satisfies any of the following conditions: the light-emitting device being a bottom-emission light-emitting device, the first light extraction layer being disposed on a surface of the cathode away from the light-emitting function layer; or the light-emitting device being a top-emission light-emitting device, the first light extraction layer being disposed on a surface of the substrate away from the light-emitting function layer.
In an example, the light-emitting device further comprises: a light extraction mesh film disposed on the light exit side of the light-emitting function layer, wherein the mesh film has a sponge pore structure.
In an example, the light-emitting device comprises a plurality of pixel units, each of the plurality of pixel units comprises a plurality of sub-pixels, and the light extraction mesh film satisfies at least one of the following conditions: the light extraction mesh film being a whole-layer structure, an orthographic projection of the light extraction mesh film on the substrate covering orthographic projections of the plurality of pixel units on the substrate; or the light extraction mesh film comprising a plurality of sub light extraction mesh films, an orthogonal projection of each of the sub light extraction mesh films on the substrate covering one of the sub pixels.
In an example, the light extraction mesh film satisfies at least one of the following conditions: a thickness of the light extraction mesh film being 10 nm to 30 microns; an aperture of the light extraction mesh film being 40 nm to 1 micron; or the light extraction mesh film containing scattering particles.
In an example, the light-emitting device satisfies any of the following conditions: (1) the light-emitting structure layer comprising a cathode, the light-emitting function layer and an anode, which are stacked, the anode being disposed close to the substrate, the light extraction mesh film satisfying any of the following conditions: (a) the light-emitting device being a bottom-emission light-emitting device, the light extraction mesh film being disposed on a surface of the light-emitting layer away from the anode; or (b) the light-emitting device being a top-emission light-emitting device, the light extraction mesh film being disposed on a surface of the substrate away from the light-emitting function layer; or (2) the light-emitting device being a backlight module, the light-emitting function layer being a light source of the backlight module, the light extraction mesh film being disposed on the light exit side of the light-emitting function layer.
In another aspect of the present application, there is provided a method of fabricating a light-emitting device. The method comprises: forming a light-emitting structure layer on one side of a substrate, the light-emitting structure layer comprising a light-emitting function layer; forming a first light extraction layer on a light exit side of the light-emitting function layer; and performing plasma treatment on a light exit surface of the first light extraction layer to form an irregular brush-like micro-nano structure.
In an example, the plasma treatment satisfies at least one of the following conditions: the plasma treatment adopting at least one of oxygen plasma or argon plasma; the plasma treatment being performed with a power of 150˜250 W; or the plasma treatment having a duration of 90˜120 seconds.
In an example, the method further comprises: forming a second light extraction layer on the light exit surface of the first light extraction layer, wherein a refractive index of the second light extraction layer is different from a refractive index of the first light extraction layer.
In an example, the method further comprises: forming a light extraction mesh film on the light exit side of the light-emitting function layer, wherein the mesh film has a sponge pore structure.
In an example, the forming a light extraction mesh film comprises: uniformly mixing raw materials for forming the light extraction mesh film to obtain a first mixture; after the first mixture is sprayed into a film, curing the film with ultraviolet radiation to obtain a cured film layer; and removing liquid crystal in the cured film layer to obtain the light extraction mesh film, wherein the raw materials comprise a monomer, a liquid crystal, a photoinitiator, and nano microbeads, or the raw materials comprise a monomer, a liquid crystal, a photoinitiator, scattering particles, and nano microbeads.
In an example, the method satisfies at least one of the following conditions: the mixing being performed using a vortex oscillator; a mass ratio of the monomer to the liquid crystal to the photoinitiator to the nano microbeads being 10:(5˜12):(0.05˜0.2):(0.1˜0.2); amount of the scattering particles being 2-10 wt % of total mass of the monomer; the curing with ultraviolet radiation being performed at a temperature of 0-30° C., a wavelength of 365 nm, an intensity of 3-15 mW/cm2, and a duration of 2-20 min; or the liquid crystal being removed by soaking in an organic solvent.
In an example, the method satisfies at least one of the following conditions: the monomer comprising at least one of an acrylate monomer, a carbonate monomer, an epoxy resin monomer, a styrene monomer, or a thiol monomer; the liquid crystal comprising at least one of a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal; the photoinitiator comprising benzoin dimethyl ether; or the nano microbeads comprising glass microbeads.
In yet another aspect of the present application, there is provided a display device or lighting device. The display device or lighting device comprises the light-emitting device described above.
Embodiments of the present application will be described in detail below. The embodiments described below are exemplary and only used for explaining the present application, and cannot be construed as limiting the present application. If the embodiments do not indicate techniques or conditions, they are performed according to the techniques or conditions described in the literature in the art or according to the product specification. If the reagents or instruments used do not indicate manufacturers, they are all conventional products which are commercially available.
In an aspect of the present application, there is provided a light-emitting device. Referring to
In the light-emitting device, the irregular brush-like micro-nano structure can change reflection and refraction conditions at the interface, so that light can be reflected and refracted to a plurality of different directions, thereby reducing the probability of occurrences of total reflection, and the irregular brush-like micro-nano structure with the shape has a greater aspect ratio, which is more beneficial to changing the reflection and refraction conditions to the direction of extracting more light, thereby significantly improving the light extraction efficiency of the light-emitting device.
According to an embodiment of the present application, the expression “irregular brush-like micro-nano structure” adopted herein refers to a plurality of micron-scale or nanometer-scale protrusions and depressions, wherein each protrusion is similar to a bristle, and the plurality of protrusions form the brush-like structure, for which reference can be made to
According to an embodiment of the present application, referring to
According to an embodiment of the present application, in the light-emitting device, the difference in refractive index between the first light extraction layer and the second light extraction layer is greater than 0.2, which can be, for example, 0.3, 0.4, 0.5, etc., and an upper limit of the difference in refractive index depends on a refractive index limit of a material. For example, it has been verified that the greater the difference in refractive index between the first light extraction layer and the second light extraction layer, the higher the light extraction efficiency of the light-emitting device, and therefore, in the case where other conditions are permissible, the difference in refractive index between the first light extraction layer and the second light extraction layer is made as great as possible. According to an embodiment of the present application, the refractive index of the first light extraction layer is greater than that of the second light extraction layer. Under this condition, the light extraction efficiency is improved more significantly.
According to an embodiment of the present application, a thickness of the second light extraction layer is less than 200 nm, which can be, for example, 180 nm, 150 nm, 120 nm, 100 nm, 80 nm, 50 nm, 30 nm, 20 nm, etc. Therefore, the effect of improving the light extraction efficiency can be achieved, and the light transmittance will not be affected by over-thickness. Further, the light exit surface of the second light extraction layer is a flat surface (refer to
According to an embodiment of the present application, a material of the first light extraction layer comprises at least one of a polymer, an inorganic material, or an organic small-molecule. In some embodiments, the material of the first light extraction layer is a polymer, for example, polymethylmethacrylate, polymethylsiloxane, polyethylmethacrylate, and the like. Therefore, the first light extraction layer has high light transmittance, wide material sources and low cost. According to an embodiment of the present application, a material of the second light extraction layer comprises at least one of a metal oxide or a metal fluoride, and in some embodiments, the material of the second light extraction layer can be, for example, aluminum oxide, zinc oxide, magnesium fluoride, etc. Further, the second light extraction layer contains scattering particles, for example, silica, zirconia, etc. Therefore, light can be further caused to scatter to different directions, which improves the light extraction efficiency.
In some embodiments, referring to
For the light-emitting structure layer having the above structure, when the light-emitting device is a bottom-emission light-emitting device, the first light extraction layer 31 can be disposed on a surface of the cathode 23 away from the light-emitting function layer 21 (refer to
According to an embodiment of the present application, referring to
According to an embodiment of the present application, a thickness of the light extraction mesh film is 10 nm to 30 microns, for example, 10 nm, 100 nm, 500 nm, 1 micron, 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, and the like. Within the thickness range, a better light extraction effect can be achieved, and the transmittance will not be affected by over-thickness. In some embodiments, an aperture of the light extraction mesh film is 40 nm to 1 micron, for example, 40 nm, 100 nm, 300 nm, 500 nm, 800 nm, 1 micron, and the like. For example, referring to
Further, the light extraction mesh film can contain scattering particles. Light propagation to various different directions can be further facilitated, to improve the light extraction efficiency.
According to an embodiment of the present application, a material of the light extraction mesh film can be a polymer, which can be, for example, a polymer formed by polymerizing at least one of an acrylate monomer, a carbonate monomer, an epoxy resin monomer, a styrene monomer, or a thiol monomer.
As described above, the light-emitting structure layer can have different structures, and the light-emitting structure layer having different structures will be described in detail below.
In some embodiments, referring to
It can be understood that, according to use needs, the light-emitting device can have a plurality of pixel units, each pixel unit has a plurality of sub-pixels, light emission colors of the plurality of sub-pixels in each pixel unit can be the same or different, and when each pixel unit comprises a plurality of sub-pixels with different light emission colors, the light-emitting device can realize color light emission. At this time, the light extraction mesh film can be a whole-layer structure, and it can also be a patterned structure provided to correspond to the sub-pixels, which is, for example, that the light extraction mesh film can be patterned through a photolithography process to form the light extraction mesh film only in the sub-pixel area, so that crosstalk between the sub-pixels can be effectively prevented while the efficiency of the light-emitting device is improved.
According to an embodiment of the present application, the light-emitting device comprises a plurality of pixel units, each of which comprises a plurality of sub-pixels, the light extraction mesh film satisfying at least one of the following conditions: the light extraction mesh film being a whole-layer structure, an orthographic projection of the light extraction mesh film on the substrate covering orthographic projections of the plurality of pixel units on the substrate; or the light extraction mesh film comprising a plurality of sub light extraction mesh films, an orthogonal projection of each of the sub light extraction mesh films on the substrate covering one of the sub-pixels.
In some embodiments, referring to
In other embodiments, referring to
In still other embodiments, in alight-emitting device capable of realizing color light emission, a sub light extraction mesh film can be disposed only in part of sub-pixels according to actual use needs. Referring to
It can be understood that the light-emitting device can have other necessary structures and components in addition to the structures described above, for example, in some embodiments, referring to
In other embodiments, the light-emitting device is a backlight module, the light-emitting function layer is a light source of the backlight module, and at this time, the light extraction mesh film can be disposed on the light exit side of the light-emitting function layer. In some embodiments, referring to
In another aspect of the present application, there is provided a method 2200 of fabricating a light-emitting device, as shown in
The steps of the method are simple, convenient and easy to implement, and the fabricated light-emitting device has a higher light extraction efficiency.
According to an embodiment of the present application, parameters of the plasma treatment can be flexibly adjusted according to actual needs, and in some embodiments, the plasma treatment is performed adopting at least one of oxygen plasma or argon plasma; the plasma treatment is performed with a power of 150-250 W, for example, 150 W, 180 W, 200 W, 220 W, 250 W, etc.; the plasma treatment is performed for a duration of 90 to 120 seconds (for example, 90 seconds, 95 seconds, 100 seconds, 105 seconds, 110 seconds, 115 seconds, 120 seconds, etc.). Within the parameter range, a better irregular brush-like micro-nano structure with the irregular brush-like shape can be realized, which has a better light extraction effect.
According to an embodiment of the present application, the method can further comprise: forming a second light extraction layer on the light exit surface of the first light extraction layer, wherein a refractive index of the second light extraction layer is different from a refractive index of the first light extraction layer. For example, the second light extraction layer can be fabricated by physical vapor deposition or chemical vapor deposition, for example, by evaporation, sputtering, or the like, and steps and parameters thereof can be selected and adjusted according to actual situations, which are not repeated here.
According to an embodiment of the present application, the method can further comprise: forming a light extraction mesh film on the light exit side of the light-emitting function layer, wherein the mesh film has a sponge pore structure. According to an embodiment of the present application, the forming a light extraction mesh film can comprise: uniformly mixing raw materials for forming the light extraction mesh film to obtain a first mixture; after the first mixture is sprayed into a film, curing the film with ultraviolet radiation to obtain a cured film layer; and removing liquid crystal in the cured film layer to obtain the light extraction mesh film, wherein the raw materials comprise a monomer, a liquid crystal, a photoinitiator, and nano microbeads, or the raw materials comprise a monomer, a liquid crystal, a photoinitiator, scattering particles, and nano microbeads. Therefore, the operation is simple and convenient, and the obtained light extraction mesh film has a better light extraction effect.
For example, the raw materials can be mixed uniformly by a vortex oscillator. Therefore, the operation is convenient and has a better mixing effect. Moreover, the liquid crystal is removed by soaking in an organic solvent, for example, the organic solvent that can be used comprising, but not limited to, propane, chloroform, tetrahydrofuran, etc. Therefore, the effect of removing the liquid crystal is better, and certainly, it can be understood that, due to process limitations and the like, in the light extraction mesh film, there may be some liquid crystal residues, which will not affect the effect of the light extraction mesh film improving the light extraction efficiency.
For example, in the method, a mass ratio of the monomer, the liquid crystal, the photoinitiator and the nano microbeads is 10:(5-12):(0.05-0.2):(0.1-0.2); amount of the scattering particles is 2-10 wt % of total mass of the monomer; and the curing with ultraviolet radiation can be performed at a temperature of 0-30° C., a wavelength of 365 nm, an intensity of 3-15 mW/cm2, and a duration of 2-20 min.
According to an embodiment of the present application, the monomer can comprise at least one of an acrylate monomer, a carbonate monomer, an epoxy resin monomer, a styrene monomer, or a thiol monomer; the liquid crystal can comprise at least one of a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal; the photoinitiator comprises benzoin dimethyl ether; the nano microbeads comprise glass microbeads; and the scattering particles comprise at least one of zirconia or silica.
It should be noted that the light extraction layer and the light extraction mesh film involved in the method of fabricating the light-emitting device can be consistent with the light extraction layer and the light extraction mesh film in the light-emitting device described above, and the light-emitting device in the method can also be consistent with the light-emitting device described above, which are not repeated here.
In yet another aspect of the present application, there is provided a display device or lighting device. According to an embodiment of the present application, the display device or lighting device comprises the light-emitting device described above. The display device or lighting device has higher light extraction efficiency, low energy consumption and better display effect or lighting effect.
It can be understood that, besides the light-emitting device described above, the display device or the lighting device can further comprise other necessary structures and components of a conventional display device or lighting device, and taking the display device as an example, the display device can further comprise a touch module, a motherboard, a battery, a housing, and the like, which are not repeated here.
Examples of the present application will be described in detail below.
A light-emitting device with a light extraction structure is shown in
A diode top-emission device based on organic small-molecule light emission was fabricated using an evaporation process. After the first light extraction layer had been evaporated, an O2 Plasma (radio frequency power: 200 W, duration: 90 s) process was performed on a surface of the first light extraction layer by reactive ion etching (RIE) technique, to form a brush-like micro-nano structure on the surface of the first light extraction layer, as shown in
In the example, the fabrication of the light extraction structure is based on the plasma process, so that the method of fabricating the light-emitting device has a simple process, extremely low cost, and significant improvement on the performance of the light-emitting device.
It was the same as the Example 1, except that the light exit surface of the first light extraction layer was not subjected to the plasma treatment.
It was the same as the Example 1, except that after the plasma treatment had been performed, an Al2O3 layer was sputtered on the light exit surface of the first light extraction layer as the second light extraction layer, which had a thickness of 70 nm and a refractive index of 1.75.
It was the same as the Example 2, except that the second light extraction layer had a material of ZnO, a thickness of 70 nm, and a refractive index of 2.0.
It was the same as the example 1, except that the light-emitting function layer was a red light quantum dot light-emitting layer, PEDOT was selected as the hole injection layer, and a quantum dot was selected as the light-emitting layer.
It was the same as the Example 4, except that the plasma treatment process was not performed on a surface of the first light extraction layer.
It was the same as the Example 1, except that the light-emitting function layer was a perovskite light-emitting layer.
It was the same as the Example 5, except that the plasma treatment process was not performed on a surface of the first light extraction layer.
The light-emitting device is a bottom-emission device (see
It was the same as the Example 6, except that on the ITO glass, spin-coating polyethyl methacrylate and sputtering magnesium fluoride were not performed.
Performance Tests
The light-emitting devices obtained in the above Examples 1 to 6 and Comparative examples 1 to 4 were subjected to a luminance and chromaticity coordinate (CIE X) test, for example, an IVL performance test using a current-voltage-luminance test system.
Luminance test results were shown in the following table:
The luminance increase ratios of the Examples 1 to 3 are increase ratios relative to the Comparative example 1, the luminance increase ratio of the Example 4 is an increase ratio relative to the Comparative example 2, the luminance increase ratio of the Example 5 is an increase ratio relative to the Comparative example 3, and the luminance increase ratio of the Example 6 is an increase ratio relative to the Comparative example 4. / denotes that the test was not performed.
Part of the CIE X test results were shown in
Raw materials: monomer A: lauryl Methacrylate (LMA), monomer B: isobornyl methacrylate (IBMA), monomer C: polyethylene glycol diacrylate-400 (PEGDA-400), mass percentages of the monomers used: monomer A/monomer B=10: 15-14:11, (monomer A+monomer B)/monomer C=6: 1-1:6; nematic liquid crystal SLC1717 being 80-120 wt % of total mass of the monomers; benzoin dimethyl ether with photoinitiator added (Irgacure 651) being 0.5-2 wt % of the total mass of the monomers; content of nano microbeads being 1-2 wt % of the total mass of the monomers.
A method of fabricating a light extraction mesh film (called a mesh film for short) is as follows: uniformly mixing the above raw materials by a vortex oscillator, spraying them on a glass surface of the ITO glass with a thickness of about 0.2-20 microns, then irradiating them using a 365 nm-ultraviolet radiometer (ultraviolet intensity: 3-15 mW/cm2) for 2-20 min at 0-30° C., then soaking them in propane for 1-10 h to remove the liquid crystal. Surface and cross-section topographies of the fabricated mesh film were shown in
An OLED light-emitting device 1: the device structure being mesh film/ITO (substrate+anode)/HIL (Hole Injection Layer) (10 nm)/HTL (Hole Transport Layer) (100 nm)/GH (host material): 5 wt % GD (green luminescent guest material with a mass ratio of 5%) (light-emitting function layer) (20 nm)/ETL (Electron Transport Layer) (40 nm)/LiF (Electron Injection Layer)/Al (cathode).
It was the same as the Example 7, except that a mesh film was not formed on ITO glass.
Raw materials: the same as those in the Example 7, except that nematic liquid crystal SLC1717 was 60-140 wt % of the total mass of the monomers.
A method of fabricating a mesh film: the same as the method in the Example 7.
The light-emitting device 2: the same as the structure in the Example 7, except that the mesh film in this example was adopted.
Raw materials: the same as those in the Example 7, except that ZrO2 scattering particles being 2-10 wt % of the total mass of the monomers was added.
A method of fabricating a mesh film: the same as the method in the Example 7.
The light-emitting device 3: the same as the structure in the Example 7, except that the mesh film in this example was adopted.
It was the same as the Example 7, except that the structure of the OLED light-emitting device was shown in
It was the same as the Example 7, except that the light-emitting device was a QLED light-emitting device and the structure of the device was shown in
It was the same as the Example 11, except that the structure of the light-emitting device was shown in
The mesh film was the same as that in the Example 7, except that the light-emitting device was an LCD backlight module and the structure of the device is shown in
Performance Tests:
The light-emitting devices obtained in the above Examples 7 to 13 and the Comparative example 5 were subjected to the IVL performance test and the chromaticity coordinate test using the current-voltage-luminance test system.
Test results were shown in the following tables and in
From the above test results, it can be seen that the current efficiency and the external quantum efficiency of the light-emitting device were significantly improved on the premise of not affecting other performances of the light-emitting device.
In the description of the present application, it should be understood that terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or as implicitly implying that the number of indicated technical features. Therefore, a feature defined with “first” or “second” can explicitly or implicitly comprise one or more of that feature. In the description of the present application, “a plurality” means two or more unless explicitly defined otherwise.
In the description of this specification, the description of reference terms “an embodiment”, “some embodiments”, “an example”, “a specific example”, or “some examples”, etc., mean that features, structures, materials, or characteristics described in conjunction with the embodiment or example are comprised in at least an embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily intended to refer to a same embodiment or example. Furthermore, the described features, structures, materials, or characteristics can be combined in any suitable manner in any one or more embodiments or examples. Moreover, in the case of no contradictions, different embodiments or examples as well as features of the different embodiments or examples described in this specification can be combined and united by those skilled in the art.
While the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as restrictions on the present application and that changes, modifications, substitutions and alterations to the above embodiments can be made by one of ordinary skill in the art within the scope of the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010493184.5 | Jun 2020 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/096053 | 5/26/2021 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2021/244369 | 12/9/2021 | WO | A |
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