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; the first lens layer and the second lens layer are arranged on the side, away from the substrate, of the color filter in a stacked mode in the thickness direction; wherein the second lens layer is the lens layer farthest from the color filter, and the first lens layer is located between the color filter and the second lens layer. According to the display panel for improving the light emitting efficiency of the OLED, the at least one first lens layer and the second lens layer which are stacked in the thickness direction are arranged, so that the problems that an existing high-refractive-index lens has color cast, and the adjustable space of brightness uniformity is limited 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 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 radiation modes can be used. The remaining 80% of the light, including substrate modes, waveguide modes, and surface plasmon modes, is confined inside the device structure and cannot be utilized.

[0003] Existing high-refractive-index lenses have poor morphological regularity, making it difficult to fabricate a standard circular structure. This results in very limited room for adjustment in improving color shift and enhancing brightness uniformity. Summary of the Invention

[0004] This invention provides a display panel for improving the light extraction efficiency of OLEDs and a method for manufacturing the same. This display panel solves the problems of color shift and limited adjustable brightness uniformity in existing high-refractive-index lenses by incorporating at least one first lens layer and one second lens layer stacked along the thickness direction.

[0005] This invention provides a display panel for improving the light extraction efficiency of OLEDs, comprising:

[0006] Substrate;

[0007] Multiple OLED units;

[0008] A color filter is disposed on the side of the OLED unit away from the substrate;

[0009] At least one first lens layer and one second lens layer are stacked along the thickness direction on the side of the color filter facing away from the substrate;

[0010] The second lens layer is the lens layer furthest from the color filter, and the first lens layer is located between the color filter and the second lens layer.

[0011] Optionally, the second lens layer has a hemispherical curved surface on the side away from the color filter and a flat surface on the side closer to the color filter.

[0012] Optionally, the first lens layer is a truncated hemispherical lens, and the first lens layer is planar on both the side away from the color filter and the side close to the color filter; wherein, the center of curvature of the truncated hemispherical lens is located on the side close to the color filter.

[0013] Optionally, in the direction from the color filter to the second lens unit, the refractive index of the first lens layer and the second lens unit increases sequentially.

[0014] Optionally, the refractive index of the first lens layer and the second lens unit is 1.6 to 1.78.

[0015] Optionally, the curvature of the first lens layer and the second lens unit increases sequentially in the direction from the color filter to the second lens unit.

[0016] Optionally, the OLED unit includes an anode pixel, an OLED layer, and a cathode pixel stacked along the thickness direction;

[0017] Anode pixels are formed on the surface of the substrate;

[0018] The orthographic projection of the anode pixel onto the substrate surface is a hexagon.

[0019] Optionally, the diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

[0020] Optionally, the thickness of the color filter film is 1.5 μm to 2 μm.

[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 unit 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] On the side of the color filter facing away from the substrate, at least one first lens layer and one second lens layer are sequentially fabricated along the thickness direction.

[0027] The second lens layer is the lens layer furthest from the color filter, and the first lens layer is located between the color filter and the second lens layer.

[0028] This invention provides a display panel for improving the light extraction efficiency of OLEDs and its fabrication method. The display panel includes: a substrate serving as a support carrier for the entire display panel; multiple OLED units providing the 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; at least one first lens layer and one second lens layer, stacked along the thickness direction on the side of the color filter facing away from the substrate; wherein the first lens layer is located between the color filter and the second lens layer, used for initial focusing of light; the second lens layer is the lens layer furthest from the color filter, used for secondary focusing of light passing through the first lens layer. The display panel for improving the light extraction efficiency of OLEDs provided by this invention solves the problems of color shift and limited adjustable brightness uniformity in existing high-refractive-index lenses by setting at least one first lens layer and one second lens layer stacked along the thickness direction. Attached Figure Description

[0029] 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;

[0030] 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;

[0031] Figure 3 This is a schematic diagram of another display panel structure for improving the light extraction efficiency of OLED provided by an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of another display panel structure for improving the light extraction efficiency of OLED provided by an embodiment of the present invention;

[0033] Figure 5 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. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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 for improving the light extraction efficiency of OLED provided by an embodiment of the present invention, wherein... Figure 2 for Figure 1 Top view of the structure shown. (Reference) Figure 1 and Figure 2 This invention provides a display panel for improving the light extraction efficiency of OLEDs, comprising:

[0037] Substrate 10;

[0038] Multiple OLED units 20;

[0039] A color filter 30 is disposed on the side of the OLED unit 20 away from the substrate 10;

[0040] At least one first lens layer 40 and one second lens layer 50 are stacked along the thickness direction on the side of the color filter 30 facing away from the substrate 10.

[0041] The second lens layer 50 is the lens layer furthest from the color filter 30, and the first lens layer 40 is located between the color filter 30 and the second lens layer 50.

[0042] Specifically, on the side of the color filter 30 facing away from the substrate 10, at least one first lens layer 40 and one second lens layer 50 are sequentially stacked. When the display panel is operating, the OLED unit emits light, which propagates in the direction facing away from the substrate 10 and passes through the color filter 30, where it is filtered into monochromatic light of a specific color (such as red, green, and blue). The monochromatic light then enters the first lens layer 40, where it initially converges the light, reducing light diffusion; subsequently, it is incident on the second lens layer 50, where it converges the light a second time. Through the synergistic light-concentrating and guiding of two or more lenses, the emission efficiency of the light emitted by the OLED unit is improved, ensuring that more light can effectively exit the display panel.

[0043] 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; at least one first lens layer and one second lens layer stacked along the thickness direction on the side of the color filter facing away from the substrate; wherein, the first lens layer is located between the color filter and the second lens layer, used for initial focusing of light; the second lens layer is the lens layer furthest from the color filter, used for secondary focusing of light passing through the first lens layer. This invention provides a display panel for improving the light extraction efficiency of OLEDs, which solves the problems of color shift and limited adjustable brightness uniformity in existing high-refractive-index lenses by setting at least one first lens layer and one second lens layer stacked along the thickness direction.

[0044] In an optional embodiment, the second lens layer 50 has a hemispherical curved surface on the side away from the color filter 30 and a flat surface on the side closer to the color filter 30.

[0045] For details, please refer to [link / reference]. Figure 1 The light-incident side of the second lens layer 50 has a planar structure to smoothly receive the light transmitted by the first lens layer 40, ensuring a stable light-converging path. The light-outceasing side of the second lens layer 50 has a curved surface structure to optimize the light emission angle after secondary convergence and reduce edge light loss.

[0046] In an optional embodiment, the first lens layer 40 is a truncated hemispherical lens, and the first lens layer 40 is planar on both the side away from the color filter 30 and the side close to the color filter 30.

[0047] The center of curvature of the truncated hemispherical lens is located on the side closest to the color filter 30.

[0048] For details, please refer to [link / reference]. Figure 1 The first lens layer 40 can be understood as a lens structure with the top portion of the hemisphere removed. Both the light-incident and light-exit sides of the first lens layer 40 are planar structures, used to directionally and initially converge the monochromatic light passing through the color filter 30. The center of curvature of the spherical surface of the first lens layer 40 is located on the side closer to the color filter 30, ensuring that the incident light converges in the thickness direction of the display panel and avoiding light divergence.

[0049] It should be noted that if the first lens layer 40 is multi-layered, during operation, the OLED unit emits light as a light source. The light propagates in the direction away from the substrate 10 and passes through the color filter 30, where it is filtered into monochromatic light of a specific color to achieve color display. Subsequently, the monochromatic light is incident on the first lens layer 40, where it is refracted and undergoes its first initial convergence. It then exits from the side away from the color filter 30 and continues to be incident on the planar side of the next first lens layer 40, repeating the above process of "incident → refraction and convergence → exit". Through the hierarchical and progressive convergence of the multi-layered first lens layers 40, the light diffusion angle is gradually reduced, making the light propagation direction closer to the thickness direction of the display panel. Through the synergistic effect of the hierarchical convergence of the multi-layered first lens layers 40 and the secondary convergence of the second lens layer 50, the loss of light propagation between layers is further reduced. Compared with the structure of a single-layered first lens layer 40, this structure can more efficiently improve the emission efficiency of the light emitted by the OLED unit, ensuring that more light effectively exits the display panel.

[0050] In an optional embodiment, the refractive indices of the first lens layer 40 and the second lens unit increase sequentially in the direction from the color filter 30 to the second lens unit.

[0051] Specifically, if the first lens layer 40 is a single layer, the refractive index of the second lens layer 50 is greater than that of the first lens layer 40. If the first lens layer 40 is multi-layered, since the refractive index of each subsequent first lens layer 40 is higher than that of the previous layer, the degree of light deflection after incident is further increased, resulting in better light converging effect. Simultaneously, due to the gradual increase in refractive index between layers, the reflection loss of light at the interlayer interfaces is significantly reduced, allowing more outgoing light to penetrate the lens layers and exit in a direction approaching the thickness of the display panel. Compared to a single-layer first lens layer 40 or a structure without a refractive index gradient, this design can more efficiently improve the emission efficiency of the OLED unit's emitted light, ensuring that more light effectively exits the display panel.

[0052] In an optional embodiment, the refractive index of the first lens layer 40 and the second lens unit is 1.6 to 1.78.

[0053] Specifically, the refractive index parameter of 1.6 to 1.78 is a special setting to adapt to lens structures with truncated hemispherical and hemispherical curved surfaces. If the refractive index is lower than 1.6, the lens's ability to refract and deflect light will be significantly weakened. The lower refractive index cannot allow the monochromatic light passing through the color filter 30 to converge at a sufficient angle. The light will still maintain a large diffusion angle when propagating inside the lens, and cannot effectively move towards the light emission direction of the display panel. If the refractive index is higher than 1.78, the light transmittance of the lens material will decrease significantly, and the absorption loss of visible light by the material will increase significantly, resulting in a reduction in the total amount of light passing through the lens layer, which will offset the light emission efficiency improvement effect brought by the light-gathering structure.

[0054] In an alternative embodiment, the curvature of the first lens layer 40 and the second lens unit increases sequentially in the direction from the color filter 30 to the second lens unit.

[0055] Specifically, if the first lens layer 40 is a single layer, the curvature of the second lens layer 50 is greater than that of the first lens layer 40. If the first lens layer 40 is multi-layered, since the curvature of each subsequent first lens layer 40 is higher than that of the previous layer, the degree of light deflection after incident is further increased, resulting in better light converging effect. Simultaneously, due to the gradual increase in curvature between layers, the diffusion angle of light during propagation continuously narrows, allowing more emitted light to maintain the preset propagation direction and exit in a direction approaching the thickness of the display panel. Compared to a single-layer first lens layer 40 or a structure without curvature gradient, this design can more efficiently improve the emission efficiency of light emitted by the OLED unit, ensuring that more light effectively exits the display panel.

[0056] In an optional embodiment, the OLED unit 20 includes an anode pixel, an OLED layer, and a cathode pixel stacked along the thickness direction;

[0057] Anode pixels are formed on the surface of substrate 10;

[0058] The orthographic projection of the anode pixel onto the surface of substrate 10 is hexagonal.

[0059] 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.

[0060] In an optional embodiment, the diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

[0061] 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.

[0062] In an optional embodiment, the thickness of the color filter 30 film layer is 1.5 μm to 2 μm.

[0063] 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 is in a reasonable proportion to the film thickness of the lens, avoiding uneven structural stress caused by excessive thickness differences and improving the overall structural stability.

[0064] Figure 3 This is a schematic diagram of another display panel structure for improving the light extraction efficiency of OLED provided by an embodiment of the present invention. Figure 4 This is a schematic diagram of another display panel structure for improving the light extraction efficiency of OLED provided by an embodiment of the present invention, wherein, Figure 4 for Figure 3 Top view of the structure shown. (Reference) Figure 3 and Figure 4 In one specific embodiment, the display panel includes:

[0065] Substrate 10;

[0066] Multiple OLED units 20;

[0067] A color filter 30 is disposed on the side of the OLED unit 20 away from the substrate 10;

[0068] At least one first lens layer 40 and one second lens layer 50 are stacked along the thickness direction on the side of the color filter 30 facing away from the substrate 10.

[0069] The second lens layer 50 is the lens layer furthest from the color filter 30, and the first lens layer 40 is located between the color filter 30 and the second lens layer 50, and the first lens layer 40 wraps around the color filter 30.

[0070] For details, please refer to Figure 3 and Figure 4On the side of the color filter 30 facing away from the substrate 10, at least one first lens layer 40 and one second lens layer 50 are sequentially stacked, with the first lens layer 40 enclosing the color filter 30 (covering the front and side areas of the color filter 30). When the display panel is operating, the OLED unit emits light, which propagates in the direction facing away from the substrate 10 and passes through the color filter 30, being filtered into monochromatic light of specific colors (such as red, green, and blue). One light path is the light emitted from the front of the color filter 30, which directly enters the front area of ​​the first lens layer 40, where it is initially converged to reduce diffusion, and then incident on the second lens layer 50 for secondary convergence, making the light propagation direction closer to the thickness direction of the display panel. The other light path is the large-angle light emitted from the sides of the color filter 30. This portion of the light is prone to total internal reflection at the interface between the color filter 30 and the surrounding medium due to an incident angle greater than the critical angle. The edge region of the first lens layer 40 (corresponding to both sides of the color filter 30) provides directional refraction and guidance, correcting the large-angle light that was originally prone to total internal reflection to a direction closer to perpendicular to the light-emitting surface of the panel, preventing the light from being trapped and absorbed inside the panel. Simultaneously, the edge region of the first lens layer 40 employs a large curvature design, which, compared to a gently curved surface, allows for a wider range of adjustment in the refraction angle of the light, covering more side-emitted light at different angles. This embodiment of the invention provides a display panel for improving the light emission efficiency of OLEDs. Through the synergistic focusing of multiple lenses and the directional refraction of the lenses on both sides, the emission efficiency of the light emitted by the OLED units is improved, ensuring that more light can effectively exit the display panel.

[0071] Figure 5 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. (Refer to...) Figure 5 The present invention also provides a method for preparing a display panel for improving the light extraction efficiency of an OLED;

[0072] The method includes:

[0073] S110 provides a substrate.

[0074] Specifically, the substrate 10 is preferably a high-purity single-crystal silicon wafer, which has excellent mechanical support properties, thermal conductivity and electrical insulation.

[0075] S120: Multiple OLED units are formed on one side of the substrate.

[0076] 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.

[0077] S130. A color filter is formed on the side of the OLED unit away from the substrate.

[0078] Specifically, a layer of red photoresist is spin-coated onto substrate 10, 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.

[0079] 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.

[0080] S140. On the side of the color filter facing away from the substrate, at least one first lens layer and a second lens layer are sequentially prepared along the thickness direction.

[0081] The second lens layer 50 is the lens layer furthest from the color filter 30, and the first lens layer 40 is located between the color filter 30 and the second lens layer 50.

[0082] Specifically, a layer of photoresist is spin-coated onto the color filter 30, and multiple exposure technology is used to complete the exposure on the surface of the color filter 30 to obtain a first lens layer 40 with a truncated hemispherical shape. The width of the truncated region in the middle of the lens layer is about 2–2.5 μm. Then, another photoresist with a higher refractive index is spin-coated, and a photomask with optimized linewidth is used. The aperture linewidth of the photomask is about 1.2–1.5 μm. Through a single exposure process, a second lens layer 50 with a hemispherical curved surface on the side opposite to the color filter can be simultaneously obtained in the RGB region.

[0083] For example, when the first lens layer 40 is a single-layer structure, its refractive index is 1.6, and the refractive index of the second lens layer 50 is 1.78.

[0084] 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 opposite to the substrate; At least one first lens layer and one second lens layer are stacked along the thickness direction on the side of the color filter facing away from the substrate; The second lens layer is the lens layer furthest from the color filter, and the first lens layer is located between the color filter and the second lens layer.

2. The display panel according to claim 1, characterized in that, The second lens layer has a hemispherical curved surface on the side away from the color filter and a flat surface on the side closer to the color filter.

3. The display panel according to claim 1, characterized in that, The first lens layer is a truncated hemispherical lens, and the first lens layer is planar on both the side away from the color filter and the side close to the color filter; wherein, the center of curvature of the truncated hemispherical lens is located on the side close to the color filter.

4. The display panel according to claim 1, characterized in that, In the direction from the color filter to the second lens unit, the refractive indices of the first lens layer and the second lens unit increase sequentially.

5. The display panel according to claim 4, characterized in that, The refractive index of the first lens layer and the second lens unit is 1.6~1.

78.

6. The display panel according to claim 1, characterized in that, In the direction from the color filter to the second lens unit, the curvature of the first lens layer and the second lens unit increases sequentially.

7. 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.

8. The display panel according to claim 7, characterized in that, The diameter of the equivalent circumcircle of the anode pixel is 5~6μm.

9. The display panel according to claim 3, characterized in that, The thickness of the color filter film is 1.5 μm to 2 μm.

10. A method for manufacturing a display panel to improve the light extraction efficiency of an OLED cell, characterized in that, Used to prepare a display panel for improving the light extraction efficiency of an OLED cell 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; On the side of the color filter facing away from the substrate, at least one first lens layer and a second lens layer are sequentially formed along the thickness direction; The second lens layer is the lens layer furthest from the color filter, and the first lens layer is located between the color filter and the second lens layer.

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