OLED display panel and preparation method thereof

Abstract

The invention relates to the technical field of display, in particular to an OLED display panel and a preparation method, and aims to solve the technical problem of how to ensure the color gamut while ensuring the high efficiency of an OLED device. In order to achieve the purpose, the OLED display panel comprises a planarization layer, an anode layer, a light-emitting material layer and a color film layer 14. The planarization layer comprises an opening area, and the opening area comprises a bottom surface and a slope surface; the anode layer at least comprises a first area located on the bottom surface and a second area located on the slope surface; the luminescent material layer is located on the first region; the color film layer 14 covers the second area and exposes the light-emitting material layer, and the optical parameter of the color film layer 14 is selected to at least reduce the optical path difference between light emitted from the front face of the light-emitting material layer and light reflected from the slope. According to the OLED device, a reflection cup structure is ensured, and a pixel definition layer is replaced by a color film, so that the optical path difference between light emitted from the front surface of a luminescent material layer and light reflected from a slope surface is effectively reduced, and the color gamut is ensured.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to an OLED display panel and a preparation method thereof. Background Art

[0002] Organic Light-Emitting Diode (OLED) has the advantages of self-luminescence, low driving voltage, high brightness, wide viewing angle, high contrast and fast response speed. It has attracted extensive attention from academia and industry and has become a strong competitor for the next generation of display and lighting technology. The anode reflector cup structure is a structure that can improve the efficiency of OLED devices. In a conventional reflector cup structure, the light emitted from the EL (Electroluminescence) layer will be transmitted laterally along the EL film layer, enter the PDL (Pixel Definition Layer) and reach the PLN (Planarization) slope, where it will be reflected to the area above the device, thereby achieving the effect of improving the front efficiency and reducing power consumption. However, due to the optical path difference between the reflected light and the original front emitted light, the color gamut will be reduced.

[0003] Accordingly, a new solution is needed in the art to solve the above problems. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the present application is proposed to solve or at least partially solve the technical problem of how to ensure the color gamut while ensuring the high efficiency of the reflective cup structure OLED device.

[0005] In a first aspect, an OLED display panel is provided, comprising:

[0006] A planarization layer, comprising an opening area, wherein the opening area comprises a bottom surface and a slope surface;

[0007] an anode layer, comprising at least a first region located on the bottom surface and a second region located on the slope surface;

[0008] a light-emitting material layer, located on the first region;

[0009] A color filter layer covers the second area and exposes the luminescent material layer, wherein the optical parameters of the color filter layer are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface.

[0010] In a technical solution of the above-mentioned OLED display panel, the optical parameters of the color filter layer are selected to eliminate the optical path difference between the light emitted from the front surface of the light-emitting material layer and the light reflected from the slope surface.

[0011] In a technical solution of the above-mentioned OLED display panel, the optical parameters include one or more of a refractive index, a transmittance and an absorption value.

[0012] In one technical solution of the above OLED display panel, the display panel includes a red light emitting material layer, a green light emitting material layer and a blue light emitting material layer.

[0013] in,

[0014] The refractive index of the color film layer corresponding to the red luminescent material layer is in the range of 1.58-1.63, the transmittance is in the range of 0.022-0.027, and the absorption value is in the range of 0.063-0.064;

[0015] The refractive index of the color film layer corresponding to the green luminescent material layer is in the range of 1.67-1.72, the transmittance is in the range of 0.675-0.68, and the absorption value is in the range of 0.006-0.007;

[0016] The refractive index of the color film layer corresponding to the blue luminescent material layer is in the range of 1.7-1.75, the transmittance is in the range of 0.004-0.005, and the absorption value is in the range of 0.067-0.068.

[0017] In a technical solution of the above OLED display panel, the planarization layer further includes a plane area surrounding the opening area;

[0018] The anode layer further includes a third region located on the planar region.

[0019] In a technical solution of the above OLED display panel, it also includes:

[0020] The cathode layer covers the color filter layer and the exposed light-emitting material layer.

[0021] In a technical solution of the above OLED display panel, it also includes:

[0022] The encapsulation layer is located on the cathode layer.

[0023] In a technical solution of the above-mentioned OLED display panel, the encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked in a direction away from the cathode layer.

[0024] In a technical solution of the above OLED display panel, it also includes:

[0025] substrate;

[0026] A driving circuit layer is located on the substrate, wherein the planarization layer is located on the driving circuit layer.

[0027] In a second aspect, a method for preparing an OLED display panel includes:

[0028] forming a planarization layer having an opening region on a substrate, wherein the opening region comprises a bottom surface and a slope surface;

[0029] forming an anode layer, comprising at least a first region located on the bottom surface and a second region located on the slope surface;

[0030] forming a light emitting material layer on the first region;

[0031] A color filter layer is formed to cover the second area and expose the luminescent material layer, wherein the optical parameters of the color filter layer are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface.

[0032] The above one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0033] In the implementation of the OLED display panel technical solution provided by the present application, the OLED display panel of the present application includes a planarization layer, an anode layer, a luminescent material layer and a color film layer. The planarization layer includes an opening area, wherein the opening area includes a bottom surface and a slope surface; the anode layer includes at least a first area located on the bottom surface and a second area located on the slope surface; the luminescent material layer is located on the first area; the color film layer covers the second area and exposes the luminescent material layer, wherein the optical parameters of the color film layer are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface. Through the above-mentioned setting method, the OLED device in the OLED display panel in the present application can ensure the reflective cup structure, and at the same time, the color film is used instead of the pixel definition layer, which can effectively reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface, and effectively ensure the color gamut. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The disclosure of the present application will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. Among them:

[0035] Figure 1 is a schematic diagram of the main components of an OLED display panel according to an embodiment of the present application;

[0036] Figure 2 It is a schematic diagram of the main components of an OLED display panel without a reflective cup structure in the prior art;

[0037] Figure 3 It is a schematic diagram of the main components of an OLED display panel with a reflective cup structure in the prior art;

[0038] Figure 4 is a schematic diagram of the refractive index of a color film according to an implementation of an embodiment of the present application;

[0039] Figure 5 is a schematic diagram of the transmittance of a color film according to an implementation of an embodiment of the present application;

[0040] Figure 6 is a schematic diagram of the absorption value of a color film according to an implementation of an embodiment of the present application;

[0041] Figure 7 is a schematic diagram of the EL spectrum of an OLED according to an implementation of an embodiment of the present application;

[0042] Figure 8 is a schematic diagram comparing brightness attenuation between an OLED display panel according to an embodiment of the present application and an OLED display panel in the prior art;

[0043] Fig. 9 It is a schematic flow chart of main steps of a method for preparing an OLED display panel according to an embodiment of the present application.

[0044] Reference numerals:

[0045] 11: planarization layer; 12: anode layer; 13: light-emitting material layer; 14: color filter layer; 15: cathode layer; 16: encapsulation layer; 161: first inorganic encapsulation layer; 162: organic encapsulation layer; 163: second inorganic encapsulation layer; 17: substrate; 171: driving circuit layer; 18: pixel definition layer. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0047] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0048] Conventional OLED devices without a reflective cup structure in the prior art are as follows: Figure 2 As shown, Figure 2 The OLED device includes a planarization layer 11 (PLN), an anode layer 12 (AND), a pixel definition layer 18 (PDL), a light-emitting material layer 13 (EL) located in the opening area of ​​the pixel definition layer 18, a cathode layer 15, and an encapsulation layer 16 (for example, it may include a first inorganic encapsulation layer 161 (CVD1), an organic encapsulation layer 162 (IJP) and a second inorganic encapsulation layer 163 (CVD2)).

[0049] Taking the green pixel as an example, the light emitted from the front side (0°) of the green light emitting material layer 13 has a CIEx of 0.23 and an efficiency of 100%.

[0050] In the prior art, OLED devices with a reflective cup structure are as follows: Figure 3 As shown, Figure 3 In the OLED device in the planarization layer 11, the planarization layer 11 includes an opening area, the opening area includes a bottom surface and a slope surface, the anode layer 12 is arranged on the planarization layer 11, and the light-emitting material layer 13 is arranged in the area where the anode layer 12 is located on the bottom surface. Similar to the structure without a reflective cup, the OLED device also includes a pixel definition layer 18 (PDL), a cathode layer 15 and an encapsulation layer 16. Among them, the encapsulation layer 16 can also include a first inorganic encapsulation layer 161 (CVD1), an organic encapsulation layer 162 (IJP) and a second inorganic encapsulation layer 163 (CVD2). The opening area of ​​the planarization layer 11 and the anode layer 12 form a reflective cup structure. The reflective cup can realize that when the light emitted from the light-emitting material layer 13 is horizontally transmitted to the slope surface of the planarization layer 11, it will be reflected at the anode layer 12 on the slope surface and reach the upper area of ​​the device, thereby improving the efficiency of the OLED device and reducing power consumption. Figure 2 The OLED device without a reflector is used as the benchmark, and the efficiency of the OLED device with a reflector is Figure 2The OLED device shown has a 10% improvement in efficiency, with a CIEx of 0.24.

[0051] However, there is an optical path difference between the light reflected by the OLED device with the reflective cup structure and the light emitted from the front side of the light-emitting material layer 13, which reduces the color gamut.

[0052] Accordingly, the art provides a new OLED display panel to solve the above problems.

[0053] See attached Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the main components of an OLED display panel according to an embodiment of the present application. Figure 1 As shown, the OLED display panel in the embodiment of the present application mainly includes a planarization layer 11 , an anode layer 12 , a light-emitting material layer 13 and a color filter layer 14 .

[0054] In this embodiment, the planarization layer 11 includes an opening area, wherein the opening area includes a bottom surface and a slope surface; the anode layer 12 includes at least a first area located on the bottom surface and a second area located on the slope surface; the luminescent material layer 13 is located on the first area; the color filter layer 14 covers the second area and exposes the luminescent material layer 13, wherein the optical parameters of the color filter layer 14 are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer 13 and the light reflected from the slope surface.

[0055] In one embodiment, the color of the color filter layer 14 can be selected according to the color of the light emitted by the luminescent material layer 13. For example, the color of the color filter layer 14 corresponding to the red luminescent material layer 13 is red, the color of the color filter layer 14 corresponding to the green luminescent material layer 13 is green, and the color of the color filter layer 14 corresponding to the blue luminescent material layer 13 is blue.

[0056] In one embodiment, the thickness of the color filter layer 14 may be greater than 0.1 micrometers and less than 4 micrometers.

[0057] In one embodiment, the color filter layer 14 may be made of resin.

[0058] In one embodiment, the optical parameters of the color filter layer 14 are selected to eliminate the optical path difference between the light emitted from the front of the luminescent material layer 13 and the light reflected from the slope surface. By replacing the pixel definition layer (PDL) in the reflective cup structure with a color filter, the optical path of the light emitted by the luminescent material layer 13 and laterally transmitted to the PDL can be eliminated, thereby eliminating the optical path difference between the light emitted from the front of the luminescent material layer 13 and the light reflected from the slope surface.

[0059] In one embodiment, the optical parameters of the color film may include one or more of a refractive index, a transmittance, and an absorptivity.

[0060] In the OLED display panel of the embodiment of the present application, a color film is used to replace the pixel definition layer (PDL). Because the color film not only realizes the function of reducing the optical path difference between the light emitted from the front of the light-emitting material layer 13 and the light reflected from the slope, it is also necessary to realize that each pixel of the OLED display panel emits light independently to reduce the color mixing phenomenon between adjacent pixels. Therefore, different optical parameters of the color film can be set corresponding to the light-emitting material layer 13 of different colors. The optical parameters may include refractive index, transmittance and absorption value. Through the optical parameters of different color films, it is possible to effectively refract the light of the color that needs to be emitted, thereby improving the efficiency of the OLED display panel and ensuring the color gamut; at the same time, it can ensure that each pixel emits light independently to avoid the color mixing phenomenon between adjacent pixels.

[0061] After multiple simulations and actual tests, the optical parameters of the color film in the embodiment of the present application can be specifically referred to in Tables 1 and Figures 4 to 6 :

[0062] Table 1 Optical parameters of color films corresponding to luminescent material layers of different colors Blue luminescent material layer 460nm Green luminescent material layer 530nm Red luminescent material layer 620nm Refractive Index 1.70～1.75 1.67～1.72 1.58～1.63 Transmittance 0.004～0.005 0.675～0.680 0.022～0.027 Absorption value 0.067～0.068 0.006～0.007 0.063～0.064

[0063] Figures 4 to 6 FIG. 4 shows lights of different wavelengths emitted by different luminescent material layers 13 , and the corresponding refractive index, transmittance and absorption value required by the color film.

[0064] In one embodiment, if Figure 1 As shown, the planarization layer 11 further includes a plane region surrounding the opening region. The anode layer 12 further includes a third region located on the plane region.

[0065] In one embodiment, if Figure 1 As shown, the OLED display panel further includes a cathode layer 15 , and the cathode layer 15 covers the color filter layer 14 and the exposed light-emitting material layer 13 .

[0066] In one embodiment, if Figure 1 As shown, the OLED display panel further includes an encapsulation layer 16 , and the encapsulation layer 16 is located on the cathode layer 15 .

[0067] In one embodiment, if Figure 1 As shown, the encapsulation layer 16 includes a first inorganic encapsulation layer 161 (CVD1), an organic encapsulation layer 162 (IJP), and a second inorganic encapsulation layer 163 (CVD2) which are disposed away from the cathode layer 15.

[0068] In one embodiment, if Figure 1 As shown, the OLED display panel may further include a substrate 17 and a driving circuit layer 171 . The driving circuit layer 171 is disposed on the substrate 17 . The planarization layer 11 is located on the driving circuit layer 171 .

[0069] See for example Figure 7 and attached Figure 8 For the green light emitting material layer, its EL spectrum is as follows Figure 7 As shown. Among them, Figure 7 The horizontal axis is the wavelength (nm), and the vertical axis is the EL intensity. Figure 2 and Figure 3 The luminance decay (L-decay) of the prior art is compared, and the comparison results are as follows Figure 8 shown.

[0070] Figure 8 In the figure, reference numeral 2 is the brightness attenuation curve in the embodiment of the present application, reference numeral 3 is the brightness attenuation curve of the reflective cup structure in the prior art, and reference numeral 4 is the brightness attenuation curve of the prior art without the reflective cup structure. Figure 8 It can be seen from the figure that the OLED display panel of the embodiment of the present application can effectively improve the brightness of the emitted light. Figure 8 The horizontal axis is the deflection angle of the outgoing light, and the vertical axis is the brightness of the outgoing light.

[0071] The OLED device in the OLED display panel in the embodiment of the present application can ensure the reflective cup structure, and the use of color film instead of the pixel definition layer can effectively reduce the optical path difference between the light emitted from the front of the luminescent material layer 13 and the light reflected from the slope surface, thereby effectively ensuring the color gamut.

[0072] Furthermore, the present application also provides a method for preparing an OLED display panel.

[0073] See attached Fig. 9 , Fig. 9 FIG. 1 is a flow chart of the main steps of a method for preparing an OLED display panel according to an embodiment of the present application. Fig. 9 As shown, the method for preparing the OLED display panel according to the embodiment of the present application mainly includes the following steps S101 to S104.

[0074] Step S101 : forming a planarization layer 11 having an opening region on a substrate 17 , wherein the opening region includes a bottom surface and a slope surface.

[0075] In this embodiment, a planarization layer 11 having an opening region may be formed on the substrate 17 .

[0076] In one embodiment, a planarization layer 11 may be formed on the substrate 17 on the entire surface first, and then the entire planarization layer 11 may be opened, thereby forming a planarization layer 11 having an opening area.

[0077] In one embodiment, the substrate 17 may be a flexible substrate such as polyimide (PI), or a rigid substrate such as glass or quartz.

[0078] Step S102: forming an anode layer 12, which at least includes a first region located on the bottom surface and a second region located on the slope surface.

[0079] In this embodiment, an anode layer 12 may be formed on the planarization layer 11. For example, the anode layer 12 may be formed by a patterning process or a deposition process, and the material of the anode layer 12 includes metal oxides such as ITO and IZO or metals such as Ag, Al, Mo or alloys thereof.

[0080] Step S103: forming a light emitting material layer 13 on the first region.

[0081] In this embodiment, a light emitting material layer 13 may be formed on the first region of the anode layer 12. The light emitting material of the light emitting material layer 13 may be an organic material, and the material of the light emitting material layer 13 may be a light emitting material that can emit a certain color of light (such as red light, blue light or green light, etc.) according to requirements.

[0082] Step S104: forming a color filter layer 14, covering the second area and exposing the luminescent material layer 13, wherein the color filter layer 14 is selected to match the color of the light emitted by the corresponding luminescent material, and in addition, its optical parameters are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer 13 and the light reflected from the slope.

[0083] In this embodiment, the color filter layer 14 may be covered on the second region of the anode layer 12 .

[0084] In one embodiment, after the first and second regions of the anode layer 12 are completely covered with the color filter layer 14, the color filter corresponding to the region of the luminescent material layer 13 is opened to expose the luminescent material layer 13. The patterned color filter layer 14 can also be directly formed by, for example, inkjet printing.

[0085] In one embodiment, the first inorganic encapsulation layer 161 of the OLED display panel can be formed by deposition, and the organic encapsulation layer 162 is formed by inkjet printing. The first inorganic encapsulation layer 161 and the second inorganic encapsulation layer 163 can be formed of inorganic materials such as silicon nitride, silicon oxide, and silicon oxynitride, and the organic encapsulation layer 162 can be formed of organic materials such as polyimide (PI) and epoxy resin.

[0086] The OLED display panel provided by the embodiments of the present disclosure or the OLED display panel obtained by the preparation method provided by the embodiments of the present disclosure can be used in a display device, and the display device can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, etc., and the embodiments of the present disclosure are not limited to this.

[0087] There are a few points to note:

[0088] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.

[0089] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0090] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to obtain new embodiments.

[0091] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. An OLED display panel, characterized in that: include: A planarization layer, comprising an opening area, wherein the opening area comprises a bottom surface and a slope surface; an anode layer, comprising at least a first region located on the bottom surface and a second region located on the slope surface; a light-emitting material layer, located on the first region; A color filter layer covers the second area and exposes the luminescent material layer, wherein the optical parameters of the color filter layer are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface.

2. The display panel according to claim 1, characterized in that: The optical parameters of the color filter layer are selected to eliminate the optical path difference between the light emitted from the front surface of the luminescent material layer and the light reflected from the slope surface.

3. The display panel according to claim 1 or 2, characterized in that: The optical parameters include one or more of a refractive index, a transmittance, and an absorption value.

4. The display panel according to claim 3, characterized in that: The display panel includes a red light emitting material layer, a green light emitting material layer and a blue light emitting material layer. in, The refractive index of the color film layer corresponding to the red luminescent material layer is in the range of 1.58-1.63, the transmittance is in the range of 0.022-0.027, and the absorption value is in the range of 0.063-0.064; The refractive index of the color film layer corresponding to the green luminescent material layer is in the range of 1.67-1.72, the transmittance is in the range of 0.675-0.68, and the absorption value is in the range of 0.006-0.007; The refractive index of the color film layer corresponding to the blue luminescent material layer is in the range of 1.7-1.75, the transmittance is in the range of 0.004-0.005, and the absorption value is in the range of 0.067-0.

068.

5. The display panel according to claim 1, characterized in that: The planarization layer further includes a planar region surrounding the opening region; The anode layer further includes a third region located on the planar region.

6. The display panel according to claim 1, characterized in that: Also includes: The cathode layer covers the color filter layer and the exposed light-emitting material layer.

7. The display panel according to claim 6, characterized in that: Also includes: The encapsulation layer is located on the cathode layer.

8. The display panel according to claim 7, characterized in that: The encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked in a direction away from the cathode layer.

9. The display panel according to claim 1, characterized in that: Also includes: substrate; A driving circuit layer is located on the substrate, wherein the planarization layer is located on the driving circuit layer.

10. A method for preparing an OLED display panel, characterized in that: include: forming a planarization layer having an opening region on a substrate, wherein the opening region comprises a bottom surface and a slope surface; forming an anode layer, comprising at least a first region located on the bottom surface and a second region located on the slope surface; forming a light emitting material layer on the first region; A color filter layer is formed to cover the second area and expose the luminescent material layer, wherein the optical parameters of the color filter layer are selected to at least reduce the optical path difference between the light emitted from the front of the luminescent material layer and the light reflected from the slope surface.

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