Display panel and manufacturing method therefor

Abstract

A display panel and a manufacturing method therefor. The display panel comprises a substrate, a planarization layer located on one side of the substrate, and micro lens units each comprising a plurality of recesses, wherein the plurality of recesses are formed in the planarization layer, and openings of the plurality of recesses are located in the surface of the side of the planarization layer facing away from the substrate; the plurality of recesses are arranged in an array; the planarization layer uses a positive adhesive material containing transparent scattering particles, and in the direction moving away from the substrate, the concentration of the transparent scattering particles in the planarization layer gradually increases; or the planarization layer uses a negative adhesive material containing transparent scattering particles, and in the direction moving away from the substrate, the concentration of the transparent scattering particles in the planarization layer gradually decreases. The display panel solves the problem in the related art that the difficulty of the manufacturing process of micro lenses in a bottom-emitting OLED display screen is large and thus it is difficult to form micro lenses having good shape.

Description

Display panel and manufacturing method thereof Technical Field

[0001] The embodiments of the present disclosure belong to the field of display technology, and particularly relate to a display panel and a method for manufacturing the same. Background Art

[0002] OLED (Organic Light-Emitting Diode) displays have attracted widespread attention due to their advantages such as self-luminescence, low power consumption, lightness, flexibility, brilliant colors, high contrast, and fast response rate. Summary of the Invention

[0003] In a first aspect, an embodiment of the present disclosure provides a display panel, comprising a substrate,

[0004] a flat layer located on one side of the substrate,

[0005] The microlens unit comprises a plurality of grooves, wherein the plurality of grooves are formed in the flat layer, and the openings of the plurality of grooves are located on a surface of the flat layer facing away from the substrate; the plurality of grooves are arranged in an array;

[0006] The flat layer is made of a positive photoresist material containing transparent scattering particles, and the concentration of the transparent scattering particles in the flat layer gradually increases in a direction away from the substrate;

[0007] Alternatively, the planar layer is made of a negative photoresist material containing transparent scattering particles, and the concentration of the transparent scattering particles in the planar layer gradually decreases in a direction away from the substrate.

[0008] In some embodiments, the planar layer includes a first sublayer and a second sublayer, wherein the first sublayer and the second sublayer are sequentially stacked away from the substrate.

[0009] The first sub-layer and the second sub-layer are both made of the positive photoresist material, and the concentration of the transparent scattering particles in the second sub-layer is greater than the concentration of the transparent scattering particles in the first sub-layer.

[0010] In some embodiments, the planar layer includes a first sublayer and a second sublayer, wherein the first sublayer and the second sublayer are sequentially stacked away from the substrate.

[0011] The first sublayer and the second sublayer both use the negative photoresist material, and the concentration of the transparent scattering particles in the second sublayer is lower than that in the first sublayer.

[0012] In some embodiments, the concentration of the transparent scattering particles in the first sub-layer is 0.

[0013] In some embodiments, the thickness of the first sub-layer is greater than the thickness of the second sub-layer.

[0014] In some embodiments, the concentration of the transparent scattering particles in the second sub-layer is 0.

[0015] In some embodiments, the thickness of the first sub-layer is less than the thickness of the second sub-layer.

[0016] In some embodiments, the groove extends from a side of the second sub-layer facing away from the substrate into the first sub-layer.

[0017] In some embodiments, the degree of scattering of incident light by the transparent scattering particles is α, α=2πr / λ;

[0018] Wherein, r is the radius of the transparent scattering particle, and λ is the wavelength of the incident light.

[0019] In some embodiments, α ≥ 0.1;

[0020] The diameter of the transparent scattering particles ranges from 20 to 25 nm.

[0021] In some embodiments, the cross-sectional shape of the groove perpendicular to the substrate includes an arc line shape,

[0022] An angle between a tangent direction of the arc line at one end away from the substrate and a tangent direction of the arc line at one end close to the substrate is in a range of 30° to 40°.

[0023] In some embodiments, in the array of grooves, the shortest distance between any two adjacent grooves is less than or equal to 0.2 μm.

[0024] In some embodiments, the opening width of the groove ranges from 3 to 5 μm;

[0025] The depth of the groove ranges from 0.5 to 2 μm.

[0026] In some embodiments, there are multiple microlens units, and the multiple microlens units are arranged in an array;

[0027] The display panel further includes a pixel defining layer and a plurality of first electrodes, which are located on a side of the planar layer away from the substrate.

[0028] The pixel defining layer is located on a side of the plurality of first electrodes away from the substrate.

[0029] A plurality of first openings are formed in the pixel defining layer, and the plurality of first openings, the plurality of first electrodes and the plurality of microlens units correspond to each other one by one.

[0030] The orthographic projections of the first opening, the first electrode, and the microlens unit on the substrate overlap;

[0031] The orthographic projection of the pixel definition layer on the substrate covers the orthographic projection of a portion of the groove at the peripheral edge of the microlens unit away from the first opening on the substrate.

[0032] In some embodiments, the material of the transparent scattering particles includes titanium dioxide.

[0033] In some embodiments, the device further includes a light-emitting functional layer and a second electrode, wherein the light-emitting functional layer and the second electrode are sequentially stacked on a side of the pixel defining layer facing away from the substrate.

[0034] The orthographic projections of the light-emitting functional layer and the second electrode on the substrate at least cover the orthographic projection of the first opening in the pixel defining layer on the substrate,

[0035] The first electrode is made of transparent conductive material.

[0036] The second electrode is made of opaque metallic conductive material.

[0037] In a second aspect, an embodiment of the present disclosure further provides a method for preparing the above-mentioned display panel, which includes: preparing a substrate;

[0038] preparing a flat layer on one side of the substrate;

[0039] The step of preparing the planar layer includes forming a pattern of the planar layer and forming microlens units in the planar layer;

[0040] Forming the microlens unit includes forming a plurality of grooves; openings of the plurality of grooves are located on a surface of the flat layer facing away from the substrate;

[0041] When the planar layer is made of a positive photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the planar layer gradually increases in a direction away from the substrate;

[0042] Alternatively, when the planar layer is made of a negative photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the planar layer gradually decreases in a direction away from the substrate.

[0043] In some embodiments, forming a microlens unit in the planar layer includes:

[0044] Applying a first flat layer material to the entire surface of one side of the substrate;

[0045] performing vacuum condensation drying and soft baking on the first flat layer material;

[0046] Applying a second layer of planar layer material on the entire surface of the first layer of planar layer material on a side facing away from the substrate;

[0047] performing vacuum condensation drying and soft baking on the second flat layer material;

[0048] Expose and develop the substrate after completing the above steps using a mask plate having a mask pattern; the mask pattern corresponds to a pattern of the microlens unit or a complementary pattern of the microlens unit;

[0049] heating the first and second planar layer materials to reflow to form the pattern of the microlens units;

[0050] The first planar layer material and the second planar layer material include positive photoresist material or negative photoresist material.

[0051] The display panel provided by the embodiment of the present disclosure can realize a flat layer with gradually changing scattering characteristics along the direction away from the substrate by setting different concentrations of transparent scattering particles at different thickness positions of the flat layer along the direction away from the substrate. On the one hand, this can change the path of the exposure light when forming the groove through the exposure process, optimize the film reduction of the groove formed by exposure in the flat layer, and then adjust the shape of the formed groove, increase the process window, and improve the light extraction effect of the groove; on the other hand, it can improve the display viewing angle of the display panel, improve the light extraction effect of the display panel, and reduce the brightness attenuation of the display panel at a large viewing angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. The above and other features and advantages will become more apparent to those skilled in the art by describing the detailed exemplary embodiments with reference to the accompanying drawings, in which:

[0053] FIG1a is a schematic diagram of light emission from a conventional OLED device without a microlens array.

[0054] FIG1 b is a schematic diagram of light emission of an OLED device equipped with a microlens array in the related art.

[0055] FIG1c is a schematic diagram showing the morphology of a microlens formed when the material of the planar layer is a negative photoresist in the related art.

[0056] FIG1d is a schematic diagram showing the morphology of a microlens formed when the material of the planar layer is a positive photoresist in the related art.

[0057] FIG. 2 a is a schematic top view of the structure of the display panel in an embodiment of the present disclosure.

[0058] FIG. 2 b is a schematic cross-sectional view of the structure of the display panel along the AA′ section line in FIG. 2 a according to an embodiment of the present disclosure.

[0059] FIG. 2 c is another schematic cross-sectional view of the display panel along the AA′ section line in FIG. 2 a according to an embodiment of the present disclosure.

[0060] FIG. 2 d is another schematic cross-sectional view of the display panel along the AA′ section line in FIG. 2 a according to an embodiment of the present disclosure.

[0061] FIG3 is a schematic cross-sectional view of a partial structure of a display panel in an embodiment of the present disclosure.

[0062] FIG4 a is a schematic diagram of the preparation process when the planar layer is made of a positive photoresist material in an embodiment of the present disclosure.

[0063] FIG4 b is a schematic diagram of the preparation process when the planar layer is made of a negative photoresist material in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0064] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, a display panel and a manufacturing method thereof provided by the embodiments of the present disclosure are further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0065] The embodiments of the present disclosure will be described more fully below with reference to the accompanying drawings, but the illustrated embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully enable those skilled in the art to understand the scope of this disclosure.

[0066] The embodiments of the present disclosure are not limited to the embodiments shown in the drawings, but include modifications of the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions shown in the drawings illustrate specific shapes of the regions, but are not intended to be limiting.

[0067] In the related art, refer to Figure 1a, which is a schematic diagram of the light output of a traditional OLED device without a microlens array. Due to the limitations of its luminescent materials and the influence of its light output mode, the light output efficiency of the OLED display is relatively low. The main reason is the internal and external waveguide effect and total reflection effect of the OLED display. Currently, the main way to improve light output is to reduce the non-luminous mode and the internal and external waveguide effect and reduce total reflection.

[0068] Referring to Figure 1b, there is a schematic diagram of light emission from an OLED device equipped with a microlens array in the related art. The microlens technology applied to OLED displays utilizes the non-flat surface pattern of the microlens to suppress total reflection at the interface, while increasing the light-emitting surface and focusing the edge light, thereby extracting more light. Top-emitting OLED devices mainly form microlenses on the encapsulation layer of the OLED device through a thermal reflow process, and improve light emission by making a microlens array (MLA) in the area corresponding to the pixel opening area on the encapsulation layer. However, there are certain process difficulties in how to form a microlens array in a WOLED (white light OLED + color film) bottom-emitting OLED display.

[0069] In the related art, referring to Figures 1c and 1d, Figure 1c is a schematic diagram of the morphology of microlenses formed when the planar layer material is a negative-tone resist in the related art; Figure 1d is a schematic diagram of the morphology of microlenses formed when the planar layer material is a positive-tone resist in the related art. The microlens array in a bottom-emission OLED display is prepared by forming a concave pit 31 of a certain curvature in the planar layer 2 corresponding to the pixel opening area through an exposure process, and then forming a pixel anode, the shape of the anode matching the shape of the concave pit 31. Currently, the materials of the planar layer 2 are mostly positive and negative resists. For negative-tone resists, the film reduction during the exposure process is small, the curvature of the corresponding concave pit 31 is small, and the light extraction effect is poor. For positive-tone resists, the film reduction during the exposure process is large, the transmittance of the corresponding concave pit 31 is low, and the spacing between adjacent concave pits 31 is large, forming a terrace between adjacent concave pits 31 away from the top of the substrate 1, resulting in a low fill rate of the microlenses (i.e., concave pits 31) in the pixel opening area and weakened light extraction.

[0070] In order to solve the problem that the microlens preparation process in the bottom-emitting OLED display screen of the related art is difficult and it is difficult to form microlenses with good morphology, in the first aspect, the embodiment of the present disclosure provides a display panel, referring to Figures 2a, 2b and 2c, Figure 2a is a schematic top view of the structure of the display panel in the embodiment of the present disclosure; Figure 2b is a schematic cross-sectional view of a structure of the display panel along the AA' section line in Figure 2a in the embodiment of the present disclosure; Figure 2c is another schematic cross-sectional view of the structure of the display panel along the AA' section line in Figure 2a in the embodiment of the present disclosure; wherein the display panel includes A substrate 1, a flat layer 2 located on one side of the substrate 1, and a microlens unit 3 including a plurality of grooves 30. The plurality of grooves 30 are formed in the flat layer 2, and the openings of the plurality of grooves are located on the surface of the flat layer 2 facing away from the substrate 1; the plurality of grooves 30 are arranged in an array; the flat layer 2 uses a positive adhesive material containing transparent scattering particles, and the concentration of the transparent scattering particles in the flat layer 2 gradually increases in a direction away from the substrate 1; alternatively, the flat layer 2 uses a negative adhesive material containing transparent scattering particles, and the concentration of the transparent scattering particles in the flat layer 2 gradually decreases in a direction away from the substrate 1.

[0071] Multiple grooves 30 are formed directly in the planar layer 2 through an exposure process (including exposure, development, and other steps). Each groove 30 is a microlens, and the microlens unit 3 includes multiple microlenses. The microlens unit 3 corresponds to the pixel opening area, and the orthographic projection of the microlens unit 3 on the substrate 1 overlaps the orthographic projection of the pixel opening area on the substrate 1. In this embodiment, the pixel is an OLED device.

[0072] In the embodiment of the present disclosure, when the flat layer 2 adopts a positive photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer 2 is gradually increased along the direction away from the substrate 1; when the grooves 30 are prepared in the flat layer 2 through the exposure process, the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 close to the substrate 1 is weaker, and the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 away from the substrate 1 is stronger, so that the lateral scattering of the exposure light parallel to the substrate 1 is enhanced, thereby forming a groove 30 structure similar to a spherical surface, and at the same time, it can enhance the exposure of the scattered exposure light to the side wall of the groove 30, reduce the shortest distance between adjacent grooves 30, and reduce the width of the raised platform formed between adjacent grooves 30, thereby improving the transmittance of light passing through the groove 30, increasing the number of grooves 30 set in the pixel opening area, that is, increasing the filling rate of the grooves 30 in the pixel opening area, and ultimately improving the light extraction rate of the pixel. When the flat layer 2 uses a negative photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer 2 gradually decreases in the direction away from the substrate 1. When the groove 30 is prepared in the flat layer 2 through the exposure process, the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 close to the substrate 1 is stronger, and the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 away from the substrate 1 is weaker, so that the longitudinal scattering of the exposure light perpendicular to the substrate 1 is enhanced, thereby increasing the film reduction in the exposure process, thereby increasing the curvature of the groove 30, and further forming a groove 30 structure similar to a spherical surface, thereby improving the light extraction effect of the groove 30.

[0073] In summary, in the embodiment of the present disclosure, by setting the concentrations of transparent scattering particles at different thickness positions of the flat layer 2 away from the substrate 1 to be different, a flat layer 2 with gradually changing scattering characteristics along the direction away from the substrate 1 can be achieved. On the one hand, when the groove 30 is formed by the exposure process, the route of the exposure light can be changed, and the film reduction of the groove 30 formed by exposure in the flat layer 2 can be optimized, thereby adjusting the shape of the formed groove 30, increasing the process window, and improving the light extraction effect of the groove 30; on the other hand, it can improve the display viewing angle of the display panel, improve the light extraction effect of the display panel, and reduce the brightness attenuation of the display panel at a large viewing angle.

[0074] In some embodiments, referring to Figure 2b, the flat layer 2 includes a first sublayer 21 and a second sublayer 22, which are stacked in sequence away from the substrate 1. The first sublayer 21 and the second sublayer 22 both use positive photoresist materials, and the concentration of transparent scattering particles in the second sublayer 22 is greater than the concentration of transparent scattering particles in the first sublayer 21.

[0075] In some embodiments, referring to FIG. 2 b , the concentration of transparent scattering particles in the first sub-layer 21 is 0, that is, the first sub-layer 21 does not include transparent scattering particles.

[0076] In some embodiments, referring to FIG. 2 b , the thickness of the first sub-layer 21 is greater than the thickness of the second sub-layer 22 .

[0077] In this embodiment, the setting of the flat layer 2 in Figure 2b can, on the one hand, adjust the lateral morphology of the groove 30 parallel to the substrate 1, so that the structure of the groove 30 is similar to a part of a sphere, reducing the width of the raised platform formed between adjacent grooves 30, thereby improving the transmittance of light passing through the groove 30, and improving the filling rate of the groove 30 in the pixel opening area, so as to improve the light extraction rate of the pixel; on the other hand, it can improve the display viewing angle of the display panel, improve the light extraction effect of the display panel, and reduce the brightness attenuation of the display panel at a large viewing angle.

[0078] In some embodiments, referring to Figure 2c, the flat layer 2 includes a first sublayer 21 and a second sublayer 22, which are stacked in sequence away from the substrate 1. The first sublayer 21 and the second sublayer 22 both use negative adhesive materials, and the concentration of transparent scattering particles in the second sublayer 22 is less than the concentration of transparent scattering particles in the first sublayer 21.

[0079] In some embodiments, referring to FIG. 2 c , the concentration of transparent scattering particles in the second sub-layer 22 is 0, that is, the second sub-layer 22 does not include transparent scattering particles.

[0080] In some embodiments, referring to FIG. 2 c , the thickness of the first sub-layer 21 is less than the thickness of the second sub-layer 22 .

[0081] In this embodiment, the setting of the flat layer 2 in Figure 2c can, on the one hand, adjust the longitudinal morphology of the groove 30 parallel to the substrate 1, so that the structure of the groove 30 is similar to a part of a sphere, increase the curvature of the groove 30, and thereby improve the light extraction effect of the groove 30; on the other hand, it can improve the display viewing angle of the display panel, improve the light extraction effect of the display panel, and reduce the brightness attenuation of the display panel at a large viewing angle.

[0082] In some embodiments, referring to FIG. 2 b and FIG. 2 c , the groove 30 extends from the side of the second sub-layer 22 facing away from the substrate 1 to the first sub-layer 21 .

[0083] In some embodiments, the degree of scattering of incident light by the transparent scattering particles is α, where α=2πr / λ; wherein r is the radius of the transparent scattering particles, and λ is the wavelength of the incident light.

[0084] In some embodiments, α≥0.1; and the diameter of the transparent scattering particles ranges from 20 to 25 nm.

[0085] In this embodiment, the transparent scattering particles adopt the Mie scattering principle. The Mie scattering principle states that when the size of the transparent scattering particles is close to or larger than the wavelength of the incident light, the intensity of the scattered light is asymmetric in all directions, and most of the incident light is scattered along the forward direction.

[0086] In some embodiments, the cross-sectional shape of the groove 30 perpendicular to the substrate 1 includes an arc shape, and the angle θ between the tangent direction Y of the arc away from the substrate 1 and the tangent direction X of the arc close to the substrate 1 ranges from 30° to 40°. Such a groove 30 structure can balance pixel efficiency and color gamut.

[0087] In some embodiments, in the array of grooves 30 , the shortest distance c between any two adjacent grooves 30 is less than or equal to 0.2 μm. The shortest distance between any two adjacent grooves 30 is the distance between adjacent edges of the two adjacent grooves 30 .

[0088] In some embodiments, the opening width a of the groove 30 ranges from 3 to 5 μm, and the depth b of the groove 30 ranges from 0.5 to 2 μm. In some embodiments, for example, the opening width a of the groove 30 is 4 μm, and the depth b of the groove 30 is 1 μm.

[0089] In some embodiments, referring to Figures 2a and 2d, Figure 2d is another structural cross-sectional schematic diagram of the display panel along the AA' section line in Figure 2a in an embodiment of the present disclosure; there are multiple microlens units 3, and the multiple microlens units 3 are arranged in an array; the display panel also includes a pixel defining layer 4 and multiple first electrodes 5, which are located on the side of the flat layer 2 facing away from the substrate 1, and the pixel defining layer 4 is located on the side of the multiple first electrodes 5 facing away from the substrate 1. A plurality of first openings 40 are opened in the pixel defining layer 4, and the multiple first openings 40, the multiple first electrodes 5 and the multiple microlens units 3 correspond one to one. The orthographic projections of the first openings 40, the first electrodes 5 and the microlens units 3 on the substrate 1 overlap and coincide in center; the orthographic projection of the pixel defining layer 4 on the substrate 1 covers the orthographic projection of the parts of the grooves 30 on the four edges of the microlens units 3 away from the first openings 40 on the substrate 1.

[0090] Subsequently, a light-emitting functional layer and a second electrode are formed in the first opening 40. The second electrode, the light-emitting functional layer, and the first electrode 5 are stacked to form a sandwich-structured OLED light-emitting device (i.e., a pixel). By ensuring that the orthographic projection of the pixel-defining layer 4 on the substrate 1 covers the orthographic projection of the portion of the groove 30 on the periphery of the microlens unit 3 that is away from the first opening 40 on the substrate 1, the problem of pixel edge leakage or edge light leakage can be avoided.

[0091] In some embodiments, the material of the planar layer 2 includes an organic resin material, and the organic resin material includes acrylic resin or polyimide.

[0092] In some embodiments, the material of the transparent scattering particles includes titanium dioxide.

[0093] In some embodiments, referring to Figure 3, which is a schematic cross-sectional view of the local structure of the display panel in the embodiment of the present disclosure; the display panel also includes a light-emitting functional layer 9 and a second electrode 10, which are sequentially stacked on the side of the pixel defining layer 4 facing away from the substrate 1, and the orthographic projections of the light-emitting functional layer 9 and the second electrode 10 on the substrate 1 at least cover the orthographic projections of the first opening 40 in the pixel defining layer 4 on the substrate 1, the first electrode 5 is made of a transparent conductive material, and the second electrode 10 is made of an opaque metal conductive material.

[0094] The first electrode 5 can be made of materials such as ITO (indium tin oxide) or IZO (indium tin zinc oxide). The second electrode 10 can be made of a metal conductive material with good reflectivity, such as aluminum, silver, or copper. The light-emitting functional layer 9 is made of an organic electroluminescent material. The first electrode 5, the light-emitting functional layer 9, and the second electrode 10 are sequentially stacked on one side of the substrate 1 to form a bottom-emitting organic electroluminescent device (i.e., an OLED device).

[0095] Based on the above structure of the display panel, an embodiment of the present disclosure further provides a method for preparing the display panel, which includes: preparing a substrate.

[0096] A flat layer is prepared on one side of the substrate.

[0097] Preparing the flat layer includes forming a pattern of the flat layer and forming microlens units in the flat layer; forming the microlens units includes forming a plurality of grooves; the openings of the plurality of grooves are located on a surface of the flat layer facing away from the substrate; when the flat layer uses a positive adhesive material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer gradually increases in a direction away from the substrate; or, when the flat layer uses a negative adhesive material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer gradually decreases in a direction away from the substrate.

[0098] In some embodiments, referring to Figures 4a and 4b, Figure 4a is a schematic diagram of the preparation process when the flat layer adopts a positive photoresist material in an embodiment of the present disclosure; Figure 4b is a schematic diagram of the preparation process when the flat layer adopts a negative photoresist material in an embodiment of the present disclosure; forming a microlens unit 3 in the flat layer 2 includes: step S101: applying a first layer of flat layer material 6 on the entire surface of one side of the substrate 1.

[0099] Step S102: vacuum condensation drying and soft baking are performed on the first flat layer material 6 .

[0100] Step S103 : applying a second layer of planar layer material 7 on the entire surface of the first layer of planar layer material 6 on the side facing away from the substrate 1 .

[0101] Step S104: vacuum condensation drying and soft baking are performed on the second flat layer material 7 .

[0102] Step S105 : using a mask plate 8 having a mask pattern 80 to expose and develop the substrate 1 after the above steps; the mask pattern 80 corresponds to the pattern of the microlens unit 3 or the complementary pattern of the microlens unit 3 .

[0103] The first planarization layer material 6 and the second planarization layer material 7 include positive photoresist material or negative photoresist material.

[0104] In this step, when both the first and second planar layer materials 6 and 7 are made of positive photoresist materials, the mask pattern 80 corresponds to the pattern of the microlens unit 3; when both the first and second planar layer materials 6 and 7 are made of negative photoresist materials, the mask pattern 80 corresponds to the complementary pattern of the microlens unit 3.

[0105] In this step, the exposure light may be UV light (ie, ultraviolet light).

[0106] Step S106 : heating the first and second planar layer materials to reflow and form patterns of the microlens units 3 .

[0107] In the method for preparing a display panel provided by the embodiment of the present disclosure, when the flat layer 2 adopts a positive photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer 2 is gradually increased in the direction away from the substrate 1; when the grooves 30 are prepared in the flat layer 2 through the exposure process, the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 close to the substrate 1 is weaker, and the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 away from the substrate 1 is stronger, so that the lateral scattering of the exposure light parallel to the substrate 1 is enhanced, thereby forming a groove 30 structure similar to a spherical surface, and at the same time, it can enhance the exposure of the scattered exposure light to the side walls of the groove 30, reduce the shortest distance between adjacent grooves 30, and reduce the width of the raised platform formed between adjacent grooves 30, thereby improving the transmittance of light passing through the groove 30, increasing the number of grooves 30 set in the pixel opening area, that is, increasing the filling rate of the grooves 30 in the pixel opening area, and ultimately improving the light extraction rate of the pixel. When the flat layer 2 uses a negative photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the flat layer 2 gradually decreases in the direction away from the substrate 1. When the groove 30 is prepared in the flat layer 2 through the exposure process, the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 close to the substrate 1 is stronger, and the scattering of the transparent scattering particles in the film layer structure of the flat layer 2 away from the substrate 1 is weaker, so that the longitudinal scattering of the exposure light perpendicular to the substrate 1 is enhanced, thereby increasing the film reduction in the exposure process, thereby increasing the curvature of the groove 30, and further forming a groove 30 structure similar to a spherical surface, thereby improving the light extraction effect of the groove 30.

[0108] In this embodiment, the pixel defining layer, the first electrode and the second electrode are prepared using traditional patterning processes, and the light-emitting functional layer is prepared using traditional processes, such as evaporation or printing processes, which will not be described here.

[0109] The display panel provided by the embodiment of the present disclosure can realize a flat layer with gradually changing scattering characteristics along the direction away from the substrate by setting different concentrations of transparent scattering particles at different thickness positions of the flat layer along the direction away from the substrate. On the one hand, this can change the path of the exposure light when forming the groove through the exposure process, optimize the film reduction of the groove formed by exposure in the flat layer, and then adjust the shape of the formed groove, increase the process window, and improve the light extraction effect of the groove; on the other hand, it can improve the display viewing angle of the display panel, improve the light extraction effect of the display panel, and reduce the brightness attenuation of the display panel at a large viewing angle.

[0110] The display panel provided in the embodiments of the present disclosure may be any product or component with a display function, such as an OLED panel, an OLED TV, an OLED billboard, a display, a mobile phone, or a navigation device.

[0111] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A display panel, wherein: Including substrate, a flat layer located on one side of the substrate, The microlens unit comprises a plurality of grooves, wherein the plurality of grooves are formed in the flat layer, and the openings of the plurality of grooves are located on a surface of the flat layer facing away from the substrate; the plurality of grooves are arranged in an array; The flat layer is made of a positive photoresist material containing transparent scattering particles, and the concentration of the transparent scattering particles in the flat layer gradually increases in a direction away from the substrate; Alternatively, the planar layer is made of a negative photoresist material containing transparent scattering particles, and the concentration of the transparent scattering particles in the planar layer gradually decreases in a direction away from the substrate.

2. The display panel according to claim 1, wherein: The planar layer includes a first sublayer and a second sublayer, wherein the first sublayer and the second sublayer are stacked in sequence away from the substrate. The first sub-layer and the second sub-layer are both made of the positive photoresist material, and the concentration of the transparent scattering particles in the second sub-layer is greater than the concentration of the transparent scattering particles in the first sub-layer.

3. The display panel according to claim 1, wherein: The planar layer includes a first sublayer and a second sublayer, wherein the first sublayer and the second sublayer are stacked in sequence away from the substrate. The first sublayer and the second sublayer both use the negative photoresist material, and the concentration of the transparent scattering particles in the second sublayer is lower than that in the first sublayer.

4. The display panel according to claim 2, wherein: The concentration of the transparent scattering particles in the first sublayer is 0.

5. The display panel according to claim 2, wherein: The thickness of the first sub-layer is greater than the thickness of the second sub-layer. The display panel according to claim 3 , wherein: The concentration of the transparent scattering particles in the second sublayer is 0.

7. The display panel according to claim 3, wherein: The thickness of the first sub-layer is smaller than the thickness of the second sub-layer.

8. The display panel according to any one of claims 2 to 7, wherein: The groove extends from a side of the second sub-layer facing away from the substrate into the first sub-layer.

9. The display panel according to any one of claims 1 to 7, wherein: The degree of scattering of incident light by the transparent scattering particles is α, α=2πr / λ; Wherein, r is the radius of the transparent scattering particle, and λ is the wavelength of the incident light.

10. The display panel according to claim 9, wherein: α≥0.1； The diameter of the transparent scattering particles ranges from 20 to 25 nm.

11. The display panel according to any one of claims 1 to 7, wherein: The cross-sectional shape of the groove perpendicular to the substrate includes an arc line shape, An angle between a tangent direction of the arc line at one end away from the substrate and a tangent direction of the arc line at one end close to the substrate is in a range of 30° to 40°.

12. The display panel according to claim 11, wherein: In the array of the grooves, the shortest distance between any two adjacent grooves is less than or equal to 0.2 μm.

13. The display panel according to claim 12, wherein: The opening width of the groove is in the range of 3 to 5 μm; The depth of the groove ranges from 0.5 to 2 μm.

14. The display panel according to claim 11, wherein: There are multiple micro lens units, and the multiple micro lens units are arranged in an array; The display panel further includes a pixel defining layer and a plurality of first electrodes, which are located on a side of the planar layer away from the substrate. The pixel defining layer is located on a side of the plurality of first electrodes away from the substrate. A plurality of first openings are formed in the pixel defining layer, and the plurality of first openings, the plurality of first electrodes and the plurality of microlens units correspond to each other one by one. The orthographic projections of the first opening, the first electrode, and the microlens unit on the substrate overlap; The orthographic projection of the pixel definition layer on the substrate covers the orthographic projection of a portion of the groove at the peripheral edge of the microlens unit away from the first opening on the substrate.

15. The display panel according to claim 1, wherein The material of the transparent scattering particles includes titanium dioxide.

16. The display panel according to claim 14, wherein: It also includes a light-emitting functional layer and a second electrode, wherein the light-emitting functional layer and the second electrode are sequentially stacked on a side of the pixel defining layer away from the substrate. The orthographic projections of the light-emitting functional layer and the second electrode on the substrate at least cover the orthographic projection of the first opening in the pixel defining layer on the substrate, The first electrode is made of transparent conductive material. The second electrode is made of opaque metallic conductive material.

17. A method for preparing a display panel according to any one of claims 1 to 16, wherein: include: preparing a substrate; preparing a flat layer on one side of the substrate; The step of preparing the planar layer includes forming a pattern of the planar layer and forming microlens units in the planar layer; Forming the microlens unit includes forming a plurality of grooves; openings of the plurality of grooves are located on a surface of the flat layer facing away from the substrate; When the planar layer is made of a positive photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the planar layer gradually increases in a direction away from the substrate; Alternatively, when the planar layer is made of a negative photoresist material containing transparent scattering particles, the concentration of the transparent scattering particles in the planar layer gradually decreases in a direction away from the substrate.

18. The method for manufacturing a display panel according to claim 17, wherein: The forming of a microlens unit in the planar layer comprises: Applying a first flat layer material to the entire surface of one side of the substrate; performing vacuum condensation drying and soft baking on the first flat layer material; Applying a second layer of planar layer material on the entire surface of the first layer of planar layer material on a side facing away from the substrate; performing vacuum condensation drying and soft baking on the second flat layer material; Expose and develop the substrate after completing the above steps using a mask plate having a mask pattern; the mask pattern corresponds to a pattern of the microlens unit or a complementary pattern of the microlens unit; heating the first and second planar layer materials to reflow to form the pattern of the microlens units; The first planar layer material and the second planar layer material include positive photoresist material or negative photoresist material.

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