Display panel

Abstract

The embodiment of the present application discloses a display panel, which comprises a driving circuit layer, an anode layer, a reflection layer, a light-emitting layer and a cathode. The anode layer is arranged on the driving circuit layer. The pixel definition layer is arranged on the driving circuit layer and covers the anode layer. The reflection layer is arranged on the driving circuit layer and covers the anode layer. The reflection layer is provided with a first opening which exposes the anode layer. The side wall of the first opening is outwardly inclined. The light-emitting layer is arranged on the anode layer in the first opening. The cathode is arranged on the light-emitting layer. The present application aims to solve the technical problem of low light-emitting efficiency of the existing OLED display device.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a display panel. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have been widely used in the display field due to their advantages such as high brightness, wide viewing angle, fast response speed, and flexible display capabilities.

[0003] In existing OLED display devices, only light with a narrow viewing angle is output during transmission, while light with a wide viewing angle is lost on the side of the pixel definition layer, resulting in low light extraction efficiency of the OLED display device. Summary of the Invention

[0004] This application provides a display panel designed to solve the technical problem of low light extraction efficiency in existing OLED display devices.

[0005] This application provides a display panel, including:

[0006] Drive circuit layer;

[0007] An anode layer is disposed on the drive circuit layer;

[0008] A reflective layer is disposed on the driving circuit layer and covers the anode layer. The reflective layer has a first opening that exposes a portion of the anode layer. The reflective layer is inclined outward on the side wall of the first opening.

[0009] A light-emitting layer, wherein the light-emitting layer is at least disposed on the anode layer within the first opening; and

[0010] A cathode, wherein the cathode is disposed at least on the light-emitting layer.

[0011] Optionally, in some embodiments of this application, the light-emitting layer extends and at least covers the sidewall of the reflective layer within the first opening.

[0012] Optionally, in some embodiments of this application, the display panel further includes a pixel definition layer disposed on the anode layer and located between the anode layer and the reflective layer. The pixel definition layer has a second opening corresponding to and connected to the first opening, and the second opening exposes a portion of the anode layer.

[0013] Optionally, in some embodiments of this application, the reflective layer extends to the sidewall of the pixel definition layer within the second opening, and the reflective layer is insulated from the anode layer.

[0014] Optionally, in some embodiments of this application, the pixel definition layer is disposed at an outward angle on the sidewall of the second opening, and the boundary of the pixel definition layer on the sidewall of the second opening is collinear with the boundary of the reflective layer on the sidewall of the first opening.

[0015] Optionally, in some embodiments of this application, the pixel definition layer forms a stepped surface on the surface of the reflective layer facing the reflective layer, the sidewall of the reflective layer at the first opening, and the sidewall of the pixel definition layer at the second opening.

[0016] Optionally, in some embodiments of this application, the thickness D1 of the reflective layer and the thickness D2 of the pixel definition layer are D1-D2≥0.5μm.

[0017] Optionally, in some embodiments of this application, the inclination angle α of the reflective layer on the sidewall of the first opening is 40°≤α≤80°.

[0018] Optionally, in some embodiments of this application, the cathode extends and covers the reflective layer, and the surface of the cathode facing the light-emitting layer is a semi-reflective surface.

[0019] Optionally, in some embodiments of this application, the reflective layer includes at least two stacked reflective sublayers, with adjacent reflective sublayers made of different materials.

[0020] Optionally, in some embodiments of this application, the wavelength λ of the light emitted by the light-emitting layer, the thickness d of the light-emitting layer, and the refractive index n of the light-emitting layer are defined to satisfy the following formula: nd=k / 4λ, where k is a positive odd number.

[0021] This application embodiment employs a display panel, which includes a driving circuit layer and an anode layer disposed on the driving circuit layer, a pixel definition layer disposed on the driving circuit layer and covering the anode layer, and a reflective layer disposed on the pixel definition layer. A first opening is formed in the reflective layer exposing a portion of the anode layer, and the reflective layer is inclined outwards from the sidewall of the first opening. The display panel also includes a light-emitting layer and a cathode, with the light-emitting layer at least disposed on the anode layer within the first opening, and the cathode at least disposed on the light-emitting layer.

[0022] By setting up a reflective layer, the large-angle light emitted by the light-emitting layer will illuminate the inclined side wall of the reflective layer when passing through the first opening. This allows the reflective layer to adjust the light path of the large-angle light to a smaller angle, reducing light loss in the light-emitting layer and increasing the overall light extraction efficiency, thus solving the technical problem of low light extraction efficiency in existing OLED display devices. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the display panel provided in the first embodiment of this application;

[0025] Figure 2 This is a schematic diagram showing the brightness and viewing angle of the reflective layer of the red light emitting layer of the display panel provided in this application when the tilt angle is 60 degrees and 70 degrees;

[0026] Figure 3 This is a schematic diagram showing the brightness and viewing angle of the reflective layer of the green light-emitting layer of the display panel provided in this application embodiment when the tilt angle is 60 degrees and 70 degrees;

[0027] Figure 4 This is a schematic diagram showing the brightness and viewing angle of the reflective layer of the blue light emitting layer of the display panel provided in this application when the tilt angle is 60 degrees and 70 degrees;

[0028] Figure 5 This is a schematic diagram of the structure of the display panel provided in the second embodiment of this application;

[0029] Figure 6 This is a schematic diagram of the optical path of the display panel provided in the second embodiment of this application;

[0030] Figure 7 This is a schematic diagram of the structure of the display panel provided in the third embodiment of this application. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0032] This application provides a display panel, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0033] Reference Figure 1 The first embodiment of this application provides a display panel 100, which includes a driving circuit layer 10, an anode layer 20, a reflective layer 30, a light-emitting layer 40, and a cathode 50. The anode layer 20 is disposed on the driving circuit layer 10. The reflective layer 30 is disposed on the driving circuit layer 10 and covers the anode layer 20. A first opening 31 is formed on the reflective layer 30, exposing a portion of the anode layer 20. The reflective layer 30 is inclined outwards from the sidewall of the first opening 31. The light-emitting layer 40 is disposed at least on the anode layer 20 within the first opening 31. The cathode 50 is disposed at least on the light-emitting layer 40.

[0034] By setting the reflective layer 30, the large-angle light emitted by the light-emitting layer 40 will illuminate the inclined side wall of the reflective layer 30 when passing through the first opening 31. This allows the reflective layer 30 to adjust the light path of the large-angle light to a smaller angle, reducing light loss in the light-emitting layer 40 and increasing the overall light extraction efficiency, thus solving the technical problem of low light extraction efficiency in existing OLED display devices.

[0035] The driving circuit layer 10 is formed with a thin film transistor (TFT), which can be a low-temperature poly-silicon (LTPS) TFT, an oxide TFT, a solid-phase crystallization (SPC) TFT, or other TFTs commonly used in the display field, and is not limited here. It should be noted that the reflective layer 30 can be a non-metallic reflective material, such as a Bragg mirror.

[0036] The anode layer 20 can be formed from one or more metals or metal oxides such as indium tin oxide (ITO), silver (Ag), aluminum (Al), or molybdenum (Mo). The light-emitting layer 40 can be formed from organic and / or inorganic materials. The light-emitting layer 40 can be formed by vapor deposition or inkjet printing. The light-emitting layer 40 can produce light of a preset color, such as blue, green, red, and white light, i.e., the light-emitting layer 40 includes a blue light-emitting layer, a green light-emitting layer, and a red light-emitting layer, and may also include a white light-emitting layer. The cathode 50 can be formed from a transparent conductive material. The cathode 50 can be formed by magnetron sputtering or physical vapor deposition. In addition, the display panel 100 also includes an encapsulation layer 90, which is disposed on the cathode 50 layer to encapsulate the display panel 100. For example, the encapsulation layer 90 can be a stacked structure formed by sequentially stacking three thin films of a first inorganic layer, an organic layer, and a second inorganic layer, or a stacked structure of more than one layer. The specific configuration can be determined by those skilled in the art according to the specific circumstances.

[0037] Optionally, the light-emitting layer 40 extends to at least cover the sidewall of the reflective layer 30 within the first opening 31. It should be noted that the light-emitting layer 40 may extend only to the sidewall of the reflective layer 30 within the first opening 31 to increase the proportion of light emitted from the first opening 31. This not only improves luminous efficiency but also avoids making the overall thickness of the display panel 100 excessive. Alternatively, the light-emitting layer 40 may extend to completely cover the reflective layer 30, thereby further enhancing the light emission effect of the light-emitting layer 40.

[0038] Optional, refer to Figure 1 The reflective layer 30 includes at least two stacked reflective sub-layers 32, with adjacent reflective sub-layers 32 made of different materials. This not only allows adjacent layers to have different refractive indices, but also results in a significant difference in refractive indices between the different materials, thereby effectively improving the reflectivity of the reflective layer 30.

[0039] Optionally, the inclination angle α of the reflective layer 30 to the sidewall of the first opening 31 is 40°≤α≤80°.

[0040] Simulation verification was conducted with the reflective layer 30 having a height of 1.55 μm. The light emission efficiency of the display panel 100 was compared by adjusting the tilt angle α of the reflective layer 30 to the side wall of the first opening 31.

[0041] Combination Figures 1 to 4The table below shows the luminance and luminous efficiency of blue (B), green (G), red (R), and white (W) light when there is no reflective layer 30, the reflective layer 30 is tilted at 60 degrees, and the reflective layer 30 is tilted at 70 degrees. Where D represents the case where the display panel 100 has no reflective layer 30, D1 represents the case where the reflective layer 30 of the display panel 100 is tilted at 60 degrees, and D2 represents the case where the reflective layer 30 of the display panel 100 is tilted at 70 degrees. Thus, it can be seen that by increasing the tilt angle of the reflective layer 30, the brightness of the display panel 100 is improved.

[0042]

[0043] Table 1

[0044] Optionally, the wavelength λ of the light emitted by the light-emitting layer 40, the thickness d of the light-emitting layer 40, and the refractive index n of the light-emitting layer 40 are defined to satisfy the following formula: nd=k / 4λ, where k is a positive odd number. k can be a positive odd number such as 1, 3, 5, or 7, and is generally taken as 5.

[0045] The wavelength range of blue light is 400nm-480nm, the wavelength range of green light is 492nm-577nm, and the wavelength range of red light is 620nm-760nm. When λ is 400nm-480nm, the emitting layer 40 can selectively transmit blue light; when λ is 492nm-577nm, the emitting layer 40 can selectively transmit green light; and when λ is 620nm-760nm, the emitting layer 40 can selectively transmit red light.

[0046] For the blue light-emitting layer, λ can be taken as 460nm; for the green light-emitting layer, λ can be taken as 530nm; and for the red light-emitting layer, λ can be taken as 620nm. Then, assuming the refractive indices n and k (k = 5) of the light-emitting layer 40 are the same, the thickness d of the blue light-emitting layer is d = 5 / 4n × 460; the thickness d of the green light-emitting layer is d = 5 / 4n × 530; and the thickness d of the red light-emitting layer is d = 5 / 4n × 620.

[0047] The relationship between the thickness d of the blue light emitting layer, the green light emitting layer and the red light emitting layer can be derived, that is, the thickness of the blue light emitting layer is less than the thickness of the green light emitting layer, and the thickness of the green light emitting layer is less than the thickness of the red light emitting layer.

[0048] In some embodiments, the refractive index of the blue light-emitting layer may be less than that of the red light-emitting layer, the refractive index of the red light-emitting layer may be less than that of the green light-emitting layer, and / or, the k-value corresponding to the blue light-emitting layer may be greater than the corresponding k-value of the red light-emitting layer, and the k-value of the red light-emitting layer may be greater than, equal to, or less than, the k-value of the green light-emitting layer, such that the thickness of the blue light-emitting layer is greater than the thickness of the green light-emitting layer, and the thickness of the green light-emitting layer is greater than the thickness of the red light-emitting layer. Since the luminous intensity of blue light is lower than that of red light, and the luminous intensity of red light is lower than that of green light, the above configuration not only allows for selective transmission of specific wavelengths of light but also improves the uniformity of the luminous intensity of the display panel 100.

[0049] By adjusting the thickness of the light-emitting layer 40 according to its different colors, and by limiting the thickness of the light-emitting layer 40 based on its type, only light of a specific wavelength can pass through the corresponding light-emitting layer 40 and be reflected by the reflective layer 30, while light of other wavelengths will be blocked by the corresponding light-emitting layer 40. In other words, by adjusting the thickness d of the light-emitting layer 40, the passage of light of a specific wavelength can be controlled, thereby reducing the influence of stray light and improving the light extraction efficiency of the specific color light emitted by the light-emitting layer 40.

[0050] Reference Figure 5 and Figure 6 In the second embodiment, the difference from the above embodiments is that the display panel 100 further includes a pixel definition layer 60. The pixel definition layer 60 is disposed on the anode layer 20 and located between the anode layer 20 and the reflective layer 30. The pixel definition layer 60 has a second opening 61 corresponding to and communicating with the first opening 31, and the second opening 61 exposes a portion of the anode layer 20. The pixel definition layer 60 can be formed from an organic photoresist material such as polyimide (PI). The pixel definition layer 60 can be prepared by inkjet printing or vapor deposition. The pixel definition layer 60 can be set after the anode layer 20, and then the reflective layer 30 can be formed on the pixel definition layer 60. Then, distributed etching is performed, first etching the reflective layer 30 to form the first opening 31, and then etching the pixel definition layer 60 to form the second opening 61. It should be noted that by setting the pixel definition layer 60 to isolate the reflective layer 30 and the anode layer 20, the reflective layer 30 can be made of a reflective metal material. When the reflective layer 30 includes multiple reflective sublayers stacked together, the reflective sublayers can be made of metallic materials such as Ti, Ag, Al, Mo, etc., and the materials of two adjacent film layers are different. That is, the reflective layer 30 can be composed of Ti layer, Al layer, Ti layer in sequence.

[0051] Furthermore, the light-emitting layer 40 extends along the sidewall of the pixel definition layer 60 at the second opening 61 to cover the sidewall of the reflective layer 30 at the first opening 31, thereby increasing the area of ​​the light-emitting layer 40 on the sidewall surface of the pixel definition layer 60, increasing the amount of light emitted by the light-emitting layer 40 toward the display direction, thereby further improving the light extraction efficiency. At the same time, it can also reduce the obstruction of light deviating from the display direction by the sidewall surface of the pixel definition layer 60, so that more light deviating from the display direction from the light-emitting layer 40 can illuminate the sidewall of the reflective layer 30.

[0052] Furthermore, the reflective layer 30 extends to the sidewall of the pixel definition layer 60 within the second opening 61, and the reflective layer 30 is insulated from the anode layer 20. This further increases the reflective surface area, further reduces light loss in the light-emitting layer 40, increases the overall light extraction efficiency, and further improves the light extraction effect. It should be noted that the reflective layer 30 is made of a non-metallic reflective material to be insulated from the anode layer 20, such as a Bragg reflector.

[0053] Furthermore, the pixel defining layer 60 is inclined outward on the sidewall of the second opening 61, and the boundary of the pixel defining layer 60 on the sidewall of the second opening 61 is collinear with the boundary of the reflective layer 30 on the sidewall of the first opening 31. This collinearity reduces the amount of light blocked by the pixel defining layer 60 from the light-emitting layer 40, allowing more light deviating from the display direction to reach the sidewall of the reflective layer 30, thereby further improving light extraction efficiency.

[0054] Furthermore, the pixel defining layer 60 is inclined outward on the sidewall of the second opening 61, and a stepped surface is formed on the surface of the pixel defining layer 60 facing the reflective layer 30, the sidewall of the reflective layer 30 in the first opening 31, and the sidewall of the pixel defining layer 60 in the second opening 61. By forming a stepped surface between the pixel defining layer 60 and the reflective layer 30, the reflective layer 30 can extend and cover the sidewall of the pixel defining layer 60 within the second opening 61, thereby improving the stability of the reflective layer 30 after its installation. Simultaneously, the formation of the light-emitting layer 40 on the sidewall of the reflective layer 30 in the first opening 31 is more stable, further improving the stability of the light-emitting layer 40 after its installation.

[0055] Optionally, the thickness D1 of the reflective layer 30 and the thickness D2 of the pixel definition layer 60 are such that D1-D2≥0.5μm. This allows the sidewall area of ​​the reflective layer 30 to be larger than the sidewall area of ​​the pixel definition layer 60, thereby increasing the reflective area of ​​the reflective layer 30. This enables the reflective layer 30 to reflect more light deviating from the display direction, further improving light extraction efficiency.

[0056] Optionally, the cathode 50 extends and covers the reflective layer 30, with the surface of the cathode 50 facing the light-emitting layer 40 being a semi-reflective surface. It is understood that a transparent metal can be deposited onto the surface of the light-emitting layer 40 using thermal evaporation to form the cathode 50. Transparent metals include Al / Ag, Ca / Ag, etc. Alternatively, a layer of transparent conductive oxide, such as ITO, can be grown on the surface of the light-emitting layer 40 using magnetron sputtering to form the cathode 50. When the cathode 50 covers the reflective layer 30, some of the light emitted from the light-emitting layer 40 is lost due to reflection from the cathode 50's surface facing the light-emitting layer 40, resulting in a decrease in light extraction efficiency. While some light from the light-emitting layer 40 can directly pass through the cathode 50 and be emitted to the outside, some reflected light is reflected back by the semi-reflective surface of the cathode 50 and oscillates back and forth between the cathode 50 and the reflective layer 30. This oscillating reflected light can still be emitted to the outside through the cathode 50, preventing light loss from the light-emitting layer 40 due to reflection by the cathode 50, thereby further improving the light extraction efficiency. Furthermore, when the light-emitting layer 40 completely extends to cover the reflective layer 30, the cathode 50 layer covers the light-emitting layer 40 to cover the reflective layer 30, that is, the reflective layer 30, the light-emitting layer 40 and the cathode 50 layer are stacked.

[0057] Reference Figure 7 In the third embodiment, the difference between this embodiment and the second embodiment is that the display panel 100 further includes an electron transport layer 70 and a hole transport layer 80. The hole transport layer is disposed between the light-emitting layer 40 and the reflective layer 30, and the electron transport layer 70 is disposed between the light-emitting layer 40 and the cathode 50. The hole transport layer and the light-emitting layer 40 can be formed using inkjet printing (IJP). The electron transport layer 70 is formed by vapor deposition. Under a certain voltage drive, electrons and holes are injected from the cathode 50 and the anode into the electron transport layer 70 and the hole transport layer 80, respectively. The electrons and holes migrate through the electron transport layer 70 and the hole transport layer 80 to the light-emitting layer 40, where they meet to form excitons and excite the light-emitting molecules to emit visible light. Both the electron transport layer 70 and the hole transport layer 80 are made of transparent material to ensure light transmission through the light-emitting layer 40.

[0058] The above provides a detailed description of a display panel provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A display panel, characterized in that, include: Drive circuit layer; An anode layer is disposed on the drive circuit layer; A reflective layer is disposed on the driving circuit layer and covers the anode layer. The reflective layer has a first opening that exposes a portion of the anode layer. The depth of the first opening is equal to the thickness of the reflective layer. The reflective layer is inclined outward on the sidewall of the first opening. The reflective layer is a non-metallic reflective material. The reflective layer includes at least two stacked reflective sub-layers, and adjacent reflective sub-layers are made of different materials. A light-emitting layer, wherein the light-emitting layer is at least disposed on the anode layer within the first opening; and A cathode, wherein the cathode is disposed at least on the light-emitting layer.

2. The display panel as described in claim 1, characterized in that, The light-emitting layer extends and at least covers the sidewall of the reflective layer within the first opening.

3. The display panel as described in claim 1, characterized in that, The display panel further includes a pixel definition layer, which is disposed on the anode layer and located between the anode layer and the reflective layer. The pixel definition layer has a second opening corresponding to and connected to the first opening, and the second opening exposes a portion of the anode layer.

4. The display panel as described in claim 3, characterized in that, The pixel definition layer is inclined outward on the side wall of the second opening, and the boundary of the pixel definition layer on the side wall of the second opening is collinear with the boundary of the reflective layer on the side wall of the first opening.

5. The display panel as described in claim 3, characterized in that, The pixel definition layer is inclined outward on the side wall of the second opening, and the pixel definition layer forms a stepped surface on the surface of the reflective layer facing the reflective layer, the side wall of the reflective layer at the first opening, and the side wall of the pixel definition layer at the second opening.

6. The display panel as described in claim 3, characterized in that, The thickness of the reflective layer is D1, and the thickness of the pixel definition layer is D2, where D1-D2≥0.5μm.

7. The display panel as described in any one of claims 1 to 6, characterized in that, The inclination angle α of the reflective layer on the sidewall of the first opening is 40°≤α≤80°.

8. The display panel as described in any one of claims 1 to 6, characterized in that, The cathode extends and covers the reflective layer, and the surface of the cathode facing the light-emitting layer is a semi-reflective surface.

9. The display panel as described in any one of claims 1 to 6, characterized in that, The wavelength λ of the light emitted by the light-emitting layer, the thickness d of the light-emitting layer, and the refractive index n of the light-emitting layer are defined to satisfy the following formula: nd = k / 4 λ, where k is a positive odd number.

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