Display panel for improving light emitting efficiency of OLED (Organic Light Emitting Diode) and preparation method thereof

Abstract

The embodiment of the invention discloses a display panel for improving the light emitting efficiency of an OLED (Organic Light Emitting Diode) and a preparation method of the display panel. A plurality of OLED units; the color filter is arranged on one side, deviating from the substrate, of the OLED unit; and the lens is arranged on the color filter and wraps the color filter. According to the display panel for improving the light emitting efficiency of the OLED, provided by the embodiment of the invention, the total reflection of emergent light can be reduced through the large-curvature edge of the lens, and the effective emergent proportion of the light is improved, so that the overall brightness and the light utilization efficiency of a display screen are directly improved; the problems of low light emitting efficiency and insufficient display brightness caused by serious light total reflection loss of a traditional OLED display panel are solved.

Description

Technical Field

[0001] This invention relates to the field of display panel technology, and more particularly to a display panel for improving the light extraction efficiency of OLED and its preparation method. Background Technology

[0002] Current silicon-based OLEDs generally use white light plus a color filter (CF) layer for colorization. In VR applications, it is generally believed that the brightness of the display should be above 1000 nits. However, due to the influence of the OLED device structure, only 20% of the radiative modes of light can be utilized. The remaining 80% of light, including substrate modes, waveguide modes, and surface plasmon modes, is confined within the device structure and cannot be used. Currently, lenses are commonly used to improve light extraction efficiency. However, because the lens is separated from the light-emitting layer by a CF layer, the current efficiency is generally low. Summary of the Invention

[0003] This invention provides a display panel for improving the light extraction efficiency of OLEDs and its manufacturing method. The display panel reduces total internal reflection of emitted light through the large curvature edge of the lens, increasing the effective light emission ratio and thus directly improving the overall brightness and light utilization efficiency of the display screen. This solves the problem of low light extraction efficiency and insufficient display brightness in traditional OLED display panels caused by severe light loss due to total internal reflection.

[0004] This invention provides a display panel for improving the light extraction efficiency of OLEDs, comprising:

[0005] Substrate;

[0006] Multiple OLED units;

[0007] A color filter is disposed on the side of the OLED unit away from the substrate;

[0008] A lens is placed on and wraps around a color filter.

[0009] Optionally, the sides of the lens are hemispherical curved surfaces, and the top is flat.

[0010] Optionally, the color filter includes red filter pixels, green filter pixels, and blue filter pixels, and the lenses wrapped around the red filter pixels, green filter pixels, and blue filter pixels have different radii of curvature.

[0011] Optionally, the radius of curvature of the lens wrapping the blue filter pixel is 1.2 μm to 1.5 μm;

[0012] The radius of curvature of the lens wrapping the green filter pixel is 1.4μm to 1.7μm;

[0013] The radius of curvature of the lens wrapped around the red filter pixel is 1.6μm to 2μm.

[0014] Optionally, the OLED unit includes an anode pixel, an OLED layer, and a cathode pixel stacked along the thickness direction;

[0015] Anode pixels are formed on the surface of the substrate;

[0016] The orthographic projection of the anode pixel onto the substrate surface is a hexagon.

[0017] Optionally, the diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

[0018] Optionally, the thickness of the color filter film is 1.5 μm to 2 μm.

[0019] Optionally, the diameter of the equivalent circumcircle of the color filter is 4 μm to 5 μm.

[0020] Optionally, the coating thickness of the lens is 2.5~3.5μm.

[0021] In a second aspect, embodiments of the present invention also provide a method for preparing a display panel for improving the light extraction efficiency of an OLED, for preparing a display panel for improving the light extraction efficiency of an OLED as described in any of the first aspects.

[0022] The method includes:

[0023] Provide substrate;

[0024] Multiple OLED cells are formed on one side of the substrate;

[0025] A color filter is formed on the side of the OLED unit that faces away from the substrate;

[0026] A lens is formed on the color filter to enclose the color filter.

[0027] This invention provides a display panel for improving the light extraction efficiency of OLEDs and its manufacturing method. The display panel includes: a substrate serving as a support for the entire display panel; multiple OLED units providing the light source for the display; a color filter disposed on the side of the OLED units facing away from the substrate, used to filter and select colors from the light emitted by the OLED units to achieve a color display effect; and a lens disposed on and surrounding the color filter, which modulates the light propagation path through its large-curvature edge. This suppresses total internal reflection loss of the light emitted from the OLED units within the display panel, reducing the proportion of light absorbed by total internal reflection; and adjusts the refraction of light propagating at large angles to a direction closer to perpendicular to the light-emitting surface, increasing the effective light emission ratio. This invention provides a display panel for improving the light extraction efficiency of OLEDs that reduces total internal reflection of emitted light through the large-curvature edge of the lens, thereby increasing the effective light emission ratio and directly improving the overall brightness and light utilization efficiency of the display screen. This solves the problem of low light extraction efficiency and insufficient display brightness in traditional OLED display panels caused by severe total internal reflection loss. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a display panel for improving the light extraction efficiency of OLED according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of another display panel structure for improving the light extraction efficiency of OLED provided in an embodiment of the present invention;

[0030] Figure 3 This is a schematic flowchart of a method for preparing a display panel to improve the light extraction efficiency of an OLED, provided by an embodiment of the present invention.

[0031] Figures 4-7 yes Figure 3 The diagram shows a structural flow chart of a method for fabricating a display panel to improve the light extraction efficiency of OLEDs. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0033] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] Figure 1 This is a schematic diagram of a display panel structure for improving the light extraction efficiency of OLED according to an embodiment of the present invention. Figure 2 This is a schematic diagram of another display panel structure provided by an embodiment of the present invention for improving the light extraction efficiency of OLEDs; wherein, Figure 2 for Figure 1 Top view of the structure shown.

[0035] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a display panel for improving the light extraction efficiency of OLEDs, comprising:

[0036] Substrate 10;

[0037] Multiple OLED units 20;

[0038] A color filter 30 is disposed on the side of the OLED unit 20 opposite to the substrate 10;

[0039] Lens 40 is disposed on and covers color filter 30.

[0040] Specifically, when the OLED unit 20 emits light, some of the light rays are incident at a relatively large angle to the interface between the color filter 30 and the air. When the angle of incidence exceeds the critical angle between the two media, total internal reflection occurs. This portion of the light is confined within the display panel, and after multiple reflections, it is absorbed by the materials, resulting in light loss and reducing the overall light extraction efficiency. Therefore, referring to... Figure 1In this embodiment of the invention, the lens 40, by wrapping around the color filter 30, uses the edge region of the lens 40 (the regions on both sides of the color filter 30) to directionally refract and guide the incident light. This allows large-angle light that would otherwise easily undergo total internal reflection to be refracted by the edge of the lens 40 and emitted in a direction closer to perpendicular to the light-emitting surface of the panel. Simultaneously, compared to a gently curved surface, the edge region with a large curvature allows for a wider range of adjustment of the refraction angle of the light, covering more angles of emitted light and further improving the effective emission ratio of the emitted light.

[0041] This invention provides a display panel for improving the light extraction efficiency of OLEDs, comprising: a substrate serving as a support for the entire display panel; multiple OLED units providing a light source for the display panel; a color filter disposed on the side of the OLED units facing away from the substrate, used to filter and select colors from the light emitted by the OLED units to achieve a color display effect; and a lens disposed on and surrounding the color filter, which modulates the light propagation path through its large-curvature edge. This suppresses total internal reflection loss of the light emitted from the OLED units within the display panel, reducing the proportion of light absorbed by total internal reflection. Furthermore, it adjusts the refraction of light propagating at large angles to a direction closer to perpendicular to the light-emitting surface, increasing the effective light emission ratio. This invention provides a display panel for improving the light extraction efficiency of OLEDs that reduces total internal reflection of emitted light through the large-curvature edge of the lens, thereby increasing the effective light emission ratio and directly improving the overall brightness and light utilization efficiency of the display screen. This solves the problem of low light extraction efficiency and insufficient display brightness in traditional OLED display panels caused by severe total internal reflection loss.

[0042] In an alternative embodiment, the side surface of the lens 40 is a hemispherical curved surface, and the top surface is a flat surface.

[0043] Specifically, the hemispherical surface has a uniform and continuously varying curvature, resulting in more consistent adjustment of the light refraction angle. This allows light emitted from the color filter 30 at different angles to be corrected to a direction nearly perpendicular to the light-emitting surface of the panel, avoiding light refraction deviations caused by sudden changes in local curvature. Simultaneously, the hemispherical surface maximizes coverage of the side light-emitting area of ​​the color filter 30, eliminating blind spots in light control, effectively suppressing total internal reflection loss, and ensuring an effective light emission ratio. The planar structure at the top of the lens 40 avoids light scattering or viewing angle distortion caused by the curved top, ensuring uniformity of the displayed image and viewing comfort. Furthermore, the planar structure is more compatible with subsequent panel encapsulation processes, providing a larger contact area and tighter fit with the encapsulation layer, improving the sealing performance of the encapsulation, reducing the corrosion of the OLED unit 20 by moisture and oxygen, and extending the lifespan of the display panel.

[0044] In an optional embodiment, the color filter 30 includes red filter pixels, green filter pixels, and blue filter pixels, and the lenses 40 wrapped around the red filter pixels, green filter pixels, and blue filter pixels have different radii of curvature.

[0045] Specifically, visible light of different wavelengths exhibits different refractive properties in the same medium. By matching lenses 40 with differentiated radii of curvature, the light extraction efficiency and color reproduction of the display panel can be further improved. For example, the refractive degrees of blue light, green light, and red light decrease sequentially, and the corresponding radii of curvature of the lenses 40 should increase sequentially.

[0046] In an optional embodiment, the radius of curvature of the lens 40 wrapped around the blue filter pixel is 1.2 μm to 1.5 μm;

[0047] The radius of curvature of the lens 40 wrapped around the green filter pixel is 1.4 μm to 1.7 μm;

[0048] The radius of curvature of the lens 40 wrapped around the red filter pixel is 1.6 μm to 2 μm.

[0049] Continue to refer to Figure 2 In an optional embodiment, the OLED unit 20 includes an anode pixel, an OLED layer, and a cathode pixel stacked along the thickness direction;

[0050] Anode pixels are formed on the surface of substrate 10;

[0051] The orthographic projection of the anode pixel onto the surface of substrate 10 is hexagonal.

[0052] Specifically, the hexagonal anode pixel configuration has seamless splicing characteristics, which can achieve gapless and tight arrangement on the surface of substrate 10, effectively improving the pixel fill factor, reducing the proportion of non-light-emitting areas, and thus improving the aperture ratio and screen brightness uniformity of the display panel.

[0053] In an optional embodiment, the diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

[0054] Specifically, this size range can ensure the effective light-emitting area of ​​the OLED layer, avoiding insufficient light intensity due to excessively small pixel size, and can also adapt to the needs of high-resolution displays, achieving high-density pixel arrangement.

[0055] In an optional embodiment, the thickness of the color filter 30 film layer is 1.5 μm to 2 μm.

[0056] Specifically, a film thickness of 1.5μm to 2μm minimizes light transmission loss within the filter while ensuring color selection accuracy. If the film is too thick, light will undergo multiple scattering and absorption within the filter, reducing the emitted light intensity; if the film is too thin, precise filtering of specific wavelengths of light cannot be achieved, leading to a decrease in color purity. Simultaneously, the film thickness of the color filter 30 and the lens 40 are in a reasonable proportion, avoiding uneven structural stress caused by excessive thickness differences and improving the overall structural stability.

[0057] In an optional embodiment, the diameter of the equivalent circumcircle of the color filter 30 is 4 μm to 5 μm.

[0058] Specifically, the equivalent circumcircle diameter of the color filter 30 is slightly smaller than that of the anode pixel, which ensures that the filter can completely cover the light-emitting area of ​​the anode pixel, avoiding color shift caused by light overflow. At the same time, a small gap is reserved for the preparation of the pixel isolation structure to prevent cross-light interference between adjacent pixels.

[0059] In an optional embodiment, the film thickness of the lens 40 is 2.5~3.5 μm.

[0060] Specifically, a film thickness of 2.5~3.5μm provides sufficient curvature space for the hemispherical side surface, ensuring the refraction control effect of lens 40 on light. Simultaneously, this thickness keeps the top plane of lens 40 flat, preventing surface curvature deformation due to insufficient thickness. Furthermore, when the film thickness of lens 40 is superimposed with the thickness of color filter 30, the light transmission path length in both media is within the optimal range, balancing the refraction control effect with light loss.

[0061] It should be noted that the film thickness on the red filter pixel, the green filter pixel, and the blue pixel is the same.

[0062] Figure 3 This is a schematic flowchart of a method for manufacturing a display panel to improve the light extraction efficiency of an OLED, provided by an embodiment of the present invention. Figures 4-7 yes Figure 3 The diagram shows a structural flow chart of a method for fabricating a display panel to improve the light extraction efficiency of OLEDs. (Reference) Figure 3 The present invention also provides a method for preparing a display panel for improving the light extraction efficiency of an OLED, which is used to prepare a display panel for improving the light extraction efficiency of an OLED as described in any of the above embodiments.

[0063] The method includes:

[0064] S110 provides a substrate.

[0065] Specifically, the substrate 10 is preferably a high-purity single-crystal silicon wafer, which has excellent mechanical support properties, thermal conductivity and electrical insulation.

[0066] S120: Multiple OLED units are formed on one side of the substrate.

[0067] Specifically, the driver chip with integrated anode is first bonded to the substrate 10. Then, using evaporation and encapsulation equipment, a light-emitting layer and a transparent cathode are sequentially deposited on the anode surface of the driver chip. Following this, a multilayer film encapsulation process is employed to fabricate a silicon-based OLED device capable of emitting white light. The anode is pre-integrated onto the surface of the driver chip using photolithography. The multilayer film encapsulation employs an alternating stacked structure of inorganic barrier layers and organic buffer layers. The inorganic barrier layer is preferably made of silicon oxide or silicon nitride, and the organic buffer layer is made of acrylate resin to effectively block moisture and oxygen corrosion, extending the lifespan of the OLED device.

[0068] S130. A color filter is formed on the side of the OLED unit away from the substrate.

[0069] For details, please refer to Figure 4 A layer of red photoresist is spin-coated onto a silicon wafer, then exposed using a stepper lithography machine, and finally developed and baked to obtain red filter pixels; the above steps are repeated to make green filter pixels and blue filter pixels respectively.

[0070] It should be noted that, in a preferred embodiment, the film thickness of the red filter pixel, green filter pixel and blue filter pixel is between 1.5-2 μm, the anode pixel is hexagonal with an outer circle diameter of 5.5 μm, and the outer circle diameter of the red filter pixel, green filter pixel and blue filter pixel can be any value between 4-5 μm.

[0071] S140. A lens is formed on the color filter to enclose the color filter.

[0072] For details, please refer to Figures 5-7 A layer of photoresist is spin-coated onto the color filter 30, and then exposed and baked to obtain a lens 40 with a film thickness of approximately 3 μm. The lenses 40 for the red, green, and blue filter pixels have the same diameter, and there are no gaps between the lenses 40, completely covering the red, green, and blue filter pixels.

[0073] The present invention provides a method for preparing a display panel for improving the light emission efficiency of an OLED, which is used to prepare a display panel for improving the light emission efficiency of an OLED as described in any of the above embodiments. The display panel prepared by this method has all the beneficial effects of the display panel described in the above embodiments. It can control the light propagation path through the large curvature edge of the lens 40, thereby suppressing the total internal reflection loss of the light emitted from the OLED unit 20 inside the display panel and improving the effective emission ratio of light.

[0074] In one specific embodiment, the color filter 30 includes red filter pixels, green filter pixels, and blue filter pixels;

[0075] A color filter 30 is formed on the OLED, comprising:

[0076] On the side of the OLED away from the anode pixel, a colored photoresist is spin-coated, and then exposed, developed, and baked to obtain a red filter pixel;

[0077] On the side of the OLED away from the anode pixel, red photoresist is spin-coated, and then exposed, developed and baked to obtain a green filter pixel;

[0078] On the side of the OLED away from the anode pixel, red photoresist is spin-coated, and then exposed, developed and baked to obtain a blue filter pixel;

[0079] A lens 40 is formed on the color filter 30 to enclose the color filter 30, comprising:

[0080] Photoresist is spin-coated onto the red filter pixel, the green filter pixel, and the blue filter pixel, and then exposed, developed, and baked to obtain a lens 40 that completely covers the red filter pixel, the green filter pixel, and the blue filter pixel, respectively.

[0081] In one specific embodiment, the curvatures of the lenses 40 on the red, green, and blue filter pixels are different. The radius of the curved portion of the lens 40 of the blue filter pixel is 1.2-1.5 μm, the radius of the lens 40 of the green filter pixel is 1.4-1.7 μm, and the radius of the lens 40 of the red filter pixel is 1.6-2 μm. The optimal conditions are a lens 40 radius of 1.4 μm for the blue filter pixel, 1.6 μm for the green filter pixel, and 1.8 μm for the red filter pixel.

[0082] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A display panel for improving the light extraction efficiency of OLEDs, characterized in that, include: Substrate; Multiple OLED units; A color filter is disposed on the side of the OLED unit that is away from the substrate; A lens is disposed on the color filter and covers the color filter.

2. The display panel according to claim 1, characterized in that, The lens has a hemispherical curved side and a flat top.

3. The display panel according to claim 2, characterized in that, The color filter includes red filter pixels, green filter pixels, and blue filter pixels, and the lenses wrapped around the red filter pixels, the green filter pixels, and the blue filter pixels have different radii of curvature.

4. The display panel according to claim 3, characterized in that, The radius of curvature of the lens wrapping the blue filter pixel is 1.2 μm to 1.5 μm; The radius of curvature of the lens wrapped around the green filter pixel is 1.4 μm to 1.7 μm; The radius of curvature of the lens wrapped around the red filter pixel is 1.6 μm to 2 μm.

5. The display panel according to claim 1, characterized in that, The OLED unit includes an anode pixel, an OLED layer, and a cathode pixel stacked along the thickness direction; The anode pixels are formed on the surface of the substrate; The orthographic projection of the anode pixel onto the substrate surface is hexagonal.

6. The display panel according to claim 5, characterized in that, The diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

7. The display panel according to claim 1, characterized in that, The thickness of the color filter film is 1.5 μm to 2 μm.

8. The display panel according to claim 1, characterized in that, The diameter of the equivalent circumcircle of the color filter is 4 μm to 5 μm.

9. The display panel according to claim 1, characterized in that, The thickness of the lens film is 2.5~3.5μm.

10. A method for manufacturing a display panel to improve the light extraction efficiency of an OLED, characterized in that, Used to prepare a display panel for improving the light extraction efficiency of OLED as described in any one of claims 1-9; The method includes: Provide substrate; Multiple OLED cells are formed on one side of the substrate; A color filter is formed on the side of the OLED unit facing away from the substrate; A lens is formed on the color filter to enclose the color filter.

Images