Light emitting diode, method for manufacturing light emitting diode, and display panel

Abstract

The application provides a light emitting diode, a preparation method of the light emitting diode and a display panel. Two surfaces of the hole injection layer arranged in the thickness direction of the anode are both outward convex curved surfaces, a non-spherical lens effect is formed to converge small-angle light and diverge large-angle light. The structure reduces interface reflection loss, improves light extraction efficiency and large-angle brightness, and improves light path consistency and color purity, so that high brightness and wide viewing angle display are realized, and power consumption caused by reduced forward light extraction efficiency in the traditional scheme is avoided.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a light-emitting diode, a method for manufacturing a light-emitting diode, and a display panel. Background Technology

[0002] OLED (Organic Light-Emitting Diode) display technology has been widely used in small-sized display panels such as smartphones and tablets. In recent years, as the application of OLED technology in medium and large-sized products such as laptops, monitors, and televisions has gradually become more widespread, its display form has become increasingly mature.

[0003] Compared to small and medium-sized products, medium and large-sized OLED display panels have more stringent requirements for viewing angle characteristics. In existing technologies, traditional solutions to improve viewing angles typically include adjusting the device's microcavity structure, optimizing the optical packaging structure, introducing microlens technology, or using viewing angle improvement films. However, while these technologies improve viewing angle performance, they often come at the cost of reduced forward light emission efficiency, leading to an increase in the overall power consumption of the display device. Summary of the Invention

[0004] The main technical problem addressed by this application is to provide a light-emitting diode, a method for fabricating a light-emitting diode, and a display panel, thereby solving the problem of how to synergistically optimize viewing angle performance and forward luminous efficacy in the prior art.

[0005] To solve the above-mentioned technical problems, the first technical solution provided in this application is: to provide a light-emitting diode, which includes an anode, a hole injection layer, a hole transport layer and a light-emitting layer stacked in sequence; In this design, the two surfaces of the hole injection layer, which are positioned opposite each other along the thickness direction of the anode, are both outwardly convex curved surfaces.

[0006] The hole injection layer has two surfaces that are arranged opposite to each other along the thickness direction of the anode, namely the first surface and the second surface, both of which are arc surfaces; the first surface is located on the side of the second surface away from the anode. The curvature of the first surface is less than the curvature of the second surface.

[0007] The light-emitting diode (LED) further includes an electron transport layer, an electron injection layer, and a cathode, which are stacked sequentially. The electron transport layer is disposed on the side of the electron injection layer closest to the anode. The surface of the electron transport layer away from the anode is an outwardly convex arc surface, and the surface of the electron transport layer close to the anode is an inwardly concave arc surface. The relative deviation between the maximum thickness of the electron transport layer and the maximum thickness of the hole injection layer is less than or equal to 5%, and the relative deviation between the edge thickness of the electron transport layer and the edge thickness of the hole injection layer is less than or equal to 5%; and / or, the maximum thickness of the hole injection layer is 20~200nm.

[0008] Among them, the electron injection layer, electron transport layer and the cathode surface away from the anode are all outwardly convex arc surfaces, and the curvature of the arc surfaces is the same.

[0009] The light-emitting layer has a third surface and a fourth surface disposed opposite to each other along the thickness direction of the anode, with the third surface disposed on the side of the fourth surface away from the anode; the third surface is an outwardly convex arc surface, and the curvature of the third surface is greater than the curvature of the fourth surface; the fourth surface is a plane or an outwardly convex arc surface.

[0010] The anode and the hole injection layer are in close contact with each other, and the surface of the anode facing the hole injection layer is a pre-curved surface that is concave inward. The radius of curvature of the pre-curved surface is 1.5mm~41mm, and the diameter of the anode is 30~180um.

[0011] In this configuration, the anode forms an orthographic projection pattern on the plane of the light-emitting diode, the aspect ratio of the orthographic projection pattern is greater than 1, and the curvature direction of the preset surface is along the radial direction of the orthographic projection pattern; or the aspect ratio of the orthographic projection pattern is equal to 1, and the preset surface is a rotationally symmetric surface with the geometric center of the orthographic projection pattern as the valley bottom.

[0012] Among them, the light-emitting diode is an electroluminescent quantum dot device, a perovskite light-emitting diode, or an organic light-emitting diode.

[0013] To solve the above-mentioned technical problems, the second technical solution provided in this application is: a method for fabricating a light-emitting diode (LED), comprising: Provide a base; An anode, a hole injection layer, a hole transport layer, and a light-emitting layer are sequentially formed on a substrate, or a light-emitting layer, a hole transport layer, a hole injection layer, and an anode are sequentially formed; wherein, the two surfaces of the hole injection layer that are opposite each other along the thickness direction of the anode are both outwardly convex curved surfaces; the hole injection layer, the hole transport layer, and the light-emitting layer are all prepared by inkjet printing.

[0014] To solve the above-mentioned technical problems, the third technical solution provided by this application is: to provide a display panel, which includes the above-mentioned light-emitting diode and driving circuit, wherein the driving circuit is used to provide driving signals to the light-emitting diode.

[0015] The beneficial effects of this application are as follows: Unlike existing technologies, this application provides a light-emitting diode (LED), a method for fabricating an LED, and a display panel. The LED includes an anode, a hole injection layer, a hole transport layer, and an emissive layer stacked sequentially. The two surfaces of the hole injection layer, positioned opposite each other along the thickness direction of the anode, are outwardly convex curved surfaces. By setting the two surfaces of the hole injection layer to be outwardly convex curved surfaces along the thickness direction of the anode, an aspherical lens effect is formed, converging small-angle light and diverging large-angle light. This structure reduces interface reflection loss, improves light extraction efficiency and brightness over a wide viewing angle, and enhances optical path consistency and color purity. Therefore, while achieving high brightness and a wide viewing angle display, it avoids the increased power consumption caused by reduced forward light extraction efficiency in traditional solutions. Attached Figure Description

[0016] 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 any creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the light-emitting diode provided in this application; Figure 2 This is a schematic diagram of the structure of an embodiment of the hole injection layer provided in this application; Figure 3 This is a schematic diagram of another embodiment of the hole injection layer provided in this application; Figure 4 This is a schematic diagram of the optical path of the hole injection layer provided in this application; Figure 5 This is a schematic diagram comparing the light emitted from the third surface of the light-emitting diode provided in this application with the light path of the prior art; Figure 6 This is a schematic diagram comparing the light emitted from the fourth surface of the light-emitting diode provided in this application with the optical path of the prior art; Figure 7 This is a schematic diagram of the structure of an embodiment of the hole injection layer and electron transport layer provided in this application; Figure 8 This is a schematic diagram of the structure of an embodiment of the anode provided in this application; Figure 9 This is a structural schematic diagram of the projected patterns of different anodes provided in this application; Figure 10 This is a schematic diagram of the structure of an embodiment of the display panel provided in this application; Figure 11 This is a flowchart illustrating one embodiment of the light-emitting diode provided in this application.

[0018] Explanation of reference numerals in the attached figures: 10. Light-emitting diode; 11. Anode; 12. Hole injection layer; 121. First surface; 122. Second surface; 123. First protrusion; 124. Second protrusion; 13. Hole transport layer; 14. Light-emitting layer; 141. Third surface; 142. Fourth surface; 15. Electron transport layer; 16. Electron injection layer; 17. Cathode; 18. Cover glass; 20. Driving circuit; 1. Display panel. Detailed Implementation

[0019] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0020] In the following description, specific details such as particular system architectures, interfaces, and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0021] The technical solutions of 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 the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. 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 device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] Please see Figures 1 to 4 , Figure 1 This is a schematic diagram of the structure of an embodiment of the light-emitting diode provided in this application. Figure 2 This is a schematic diagram of the structure of an embodiment of the hole injection layer provided in this application. Figure 3 This is a schematic diagram of another embodiment of the hole injection layer provided in this application. Figure 4 This is a schematic diagram of the optical path of the hole injection layer provided in this application. Figure 4 The portions shown in (c1) and (c2) represent schematic diagrams of the light paths of light incident at different incident angles onto the first surface 121 in the hole injection layer 12. Figure 2 and Figure 3 In the figures, d1 represents the center thickness of the first protrusion 123. Figure 2 and Figure 3 In the figure, d2 represents the center thickness of the second protrusion 124.

[0025] This application provides a light-emitting diode 10, which includes an anode 11, a hole injection layer 12, a hole transport layer 13 and a light-emitting layer 14 stacked sequentially; wherein, the two surfaces of the hole injection layer 12, which are arranged opposite to each other along the thickness direction of the anode 11, are both outwardly convex curved surfaces.

[0026] By configuring the hole injection layer 12 with two outwardly convex curved surfaces positioned opposite each other along the thickness direction of the anode 11, an aspherical lens effect is formed to converge small-angle light and diverge large-angle light. This structure reduces interface reflection loss, improves light extraction efficiency and brightness over a wide viewing angle, and enhances optical path consistency and color purity. Thus, while achieving high brightness and wide viewing angle displays, it avoids the increased power consumption caused by reduced forward light extraction efficiency in traditional solutions.

[0027] The two surfaces of the hole injection layer 12, which are arranged opposite each other along the thickness direction of the anode 11 (i.e., the surface in contact with the anode 11 and the surface in contact with the hole transport layer 13), are both designed as outwardly convex curved surfaces. Exemplarily, this curved surface structure is typically formed using a solution-based process, particularly inkjet printing combined with vacuum drying. In a specific embodiment, by adjusting the ink viscosity and printing parameters, the spreading and drying process of the droplets on the surface of the anode 11 is controlled. Utilizing the difference in surface tension and solvent evaporation rate, the film naturally forms a biconvex lens-like morphology after curing, thicker at the center and thinner at the edges.

[0028] In some embodiments, the hole injection layer 12 has two surfaces disposed opposite to each other along the thickness direction of the anode 11, namely a first surface 121 and a second surface 122, both of which are arc surfaces; the first surface 121 is disposed on the side of the second surface 122 away from the anode 11; the curvature of the first surface 121 is less than the curvature of the second surface 122.

[0029] The hole injection layer 12 includes a first protrusion 123 and a second protrusion 124 stacked together, with the surfaces of the first protrusion 123 and the second protrusion 124 that are close to each other being planar. The first protrusion 123 is disposed on the side of the second protrusion 124 away from the anode 11. The first surface 121 is the surface of the first protrusion 123 away from the anode 11, and the second surface 122 is the surface of the second protrusion 124 close to the anode 11.

[0030] The curvature of the first surface 121 is less than that of the second surface 122, which means that the second surface 122 has a higher degree of curvature relative to the first surface 121, or in other words, the radius of curvature of the second surface 122 is smaller than that of the first surface 121. This asymmetric curvature design can be achieved through solution-based processes, such as inkjet printing. By controlling the wettability of the ink on the surface of the anode 11, the solvent evaporation rate, and the surface tension gradient during vacuum drying, the film can form an asymmetric biconvex structure with a relatively flat upper surface and a lower surface that adheres to the anode 11 and has a larger curvature during curvature.

[0031] The curvature of the first surface 121 is less than that of the second surface 122, making the maximum thickness of the first protrusion 123 less than the maximum thickness of the second protrusion 124. The hole injection layer 12 adopts an asymmetric gradient structure with a thickness less on the side away from the anode 11 than on the side closer to the anode 11. This design not only optimizes hole injection efficiency and reduces contact resistance by maintaining a thicker layer near the anode 11 interface, but more importantly, it uses the thickness gradient to compensate for the optical path difference under different emission angles, effectively suppressing phase interference changes of large-angle light rays, thereby significantly reducing viewpoint angular deviation. At the same time, this gradient geometry helps to smooth the internal electric field distribution and alleviate interface stress, improving light extraction efficiency while significantly improving the emission color purity and color uniformity of the device over a wide viewing angle.

[0032] For example, in the thickness direction of the anode 11, the highest point of the first protrusion 123, the lowest point of the second protrusion 124, and the geometric center of the hole injection layer 12 are located on the same straight line, and this straight line is parallel to the thickness direction of the anode 11 (that is, the highest point of the first protrusion 123, the lowest point of the second protrusion 124, and the geometric center of the hole injection layer 12 are all arranged to coincide in the plane direction of the light-emitting diode 10), that is, the center thickness of the hole injection layer 12 is the largest, so as to optimize the forward light emission efficiency as much as possible.

[0033] In other embodiments, in the planar direction of the light-emitting diode 10, at least two points of the highest point of the first protrusion 123, the lowest point of the second protrusion 124, and the geometric center of the hole injection layer 12 are offset from each other. For example, in the planar direction of the light-emitting diode 10, the highest point of the first protrusion 123 and the lowest point of the second protrusion 124 are located on the left and right sides of the geometric center of the hole injection layer 12, respectively; or, in the planar direction of the light-emitting diode 10, the highest point of the first protrusion 123 and the lowest point of the second protrusion 124 coincide and are offset from the geometric center of the hole injection layer 12.

[0034] In some embodiments, such as Figure 2 As shown, the first protrusion 123 and the second protrusion 124 are in contact, and the contact surface between them is planar. That is, the cross-section of the hole injection layer 12 in the thickness direction of the anode 11 is approximately elliptical. The sum of the maximum thickness of the first protrusion 123 and the maximum thickness of the second protrusion 124 is 20~200nm.

[0035] In other embodiments, such as Figure 3 As shown, the first protrusion 123 and the second protrusion 124 are spaced apart, and the maximum thickness of the hole injection layer 12 is 20~200nm.

[0036] By defining both the first surface 121 and the second surface 122 of the hole injection layer 12 as curved surfaces, with the curvature of the first surface 121 being less than that of the second surface 122, the hole injection layer 12 forms an asymmetric lens structure. This asymmetric structure facilitates more precise optical control based on the specific path of light propagation, allowing light emitted from the light-emitting layer 14 to be more effectively refracted, converged, or diverged when passing through the hole injection layer 12. Particularly for large-angle light, it further optimizes the refraction angle at the interface, reducing energy loss due to total internal reflection. Simultaneously, this specific curvature distribution promotes a more uniform electric field distribution within the hole injection layer 12, facilitating uniform hole injection and transport, thereby improving the electrical performance stability of the device. Furthermore, the asymmetric curved surface design can further enhance light extraction efficiency through geometric optimization of a single-layer material without adding additional optical film layers. This allows the device to maintain high forward brightness while significantly improving brightness attenuation characteristics at lateral viewing angles, achieving a balance between wide viewing angle and high efficiency.

[0037] Please see Figure 1 , Figures 5 to 7 , Figure 5 This is a schematic diagram comparing the light emitted from the third surface of the light-emitting diode provided in this application with the optical path of the prior art. Figure 6 This is a schematic diagram comparing the light emitted from the fourth surface of the light-emitting diode provided in this application with the optical path of the prior art. Figure 7 This is a schematic diagram of an embodiment of the hole injection layer and electron transport layer provided in this application. Figure 7 In this diagram, d3 represents the center thickness of the hole injection layer 12, d4 represents the center thickness of the electron transport layer 15, d5 represents the edge thickness of the hole injection layer 12, and d6 represents the edge thickness of the electron transport layer 15.

[0038] In some embodiments, the light-emitting diode 10 further includes an electron transport layer 15, an electron injection layer 16, and a cathode 17 stacked sequentially. The electron transport layer 15 is disposed on the side of the electron injection layer 16 near the anode 11. The surface of the electron transport layer 15 away from the anode 11 is an outwardly convex arc surface, and the surface of the electron transport layer 15 near the anode 11 is an inwardly concave arc surface. The relative deviation between the maximum thickness of the electron transport layer 15 and the maximum thickness of the hole injection layer 12 is less than or equal to 5%, and the relative deviation between the edge thickness of the electron transport layer 15 and the edge thickness of the hole injection layer 12 is less than or equal to 5%. And / or, the maximum thickness of the hole injection layer 12 is 20~200nm.

[0039] By defining the surface of the electron transport layer 15 furthest from the anode 11 as an outwardly convex arc surface and the surface closest to the anode 11 as an inwardly concave arc surface, the electron transport layer 15 forms a lens structure with asymmetric curvature. This structure facilitates secondary optical manipulation of light emitted from the light-emitting layer 14, especially for large-angle light. It can change the propagation direction through interface refraction, increasing the angular range of the light escape cone, thereby improving the extraction efficiency of large-angle light and enhancing the device's lateral viewing angle performance.

[0040] The light-emitting diode 10 includes an anode 11, a hole injection layer 12, a hole transport layer 13, a light-emitting layer 14, an electron transport layer 15, an electron injection layer 16, and a cathode 17, which are stacked sequentially, and any two adjacent layers are in contact with each other. That is, the first surface 121 of the hole injection layer 12 is the contact surface between the hole injection layer 12 and the hole transport layer 13, and the second surface 122 of the hole injection layer 12 is the contact surface between the hole injection layer 12 and the anode 11.

[0041] The anode 11 can be placed at the bottom of the light-emitting diode 10 as the bottom electrode (conventional upright structure) or at the top of the light-emitting diode 10 as the top electrode (inverted structure), thus adapting to different device architecture requirements.

[0042] The following description mainly uses anode 11 as the bottom electrode.

[0043] The electron transport layer 15 exhibits a geometry that is thicker in the middle and thinner at the edges. The hole injection layer 12 also exhibits a geometry that is thicker in the middle and thinner at the edges.

[0044] The relative deviation is defined as the ratio of the absolute value of the thickness difference between the two to the larger of the two thickness values.

[0045] For example, the highest point of the first protrusion 123, the lowest point of the second protrusion 124, and the geometric center of the hole injection layer 12 are all aligned in the planar direction of the light-emitting diode 10, that is, the center thickness of the first protrusion 123 and the second protrusion 124 is the greatest. In some embodiments, such as Figure 7 As shown, the center thickness of the first protrusion 123 and the second protrusion 124 is the largest, and the relative deviation between the center thickness of the electron transport layer 15 and the center thickness of the hole injection layer 12 is less than or equal to 5%. This consistency in thickness between the electron transport layer 15 and the hole injection layer 12 effectively avoids optical color shift and charge imbalance problems caused by uneven film thickness.

[0046] By limiting the relative deviation between the maximum thickness and edge thickness of the electron transport layer 15 and the maximum thickness and edge thickness of the hole injection layer 12 to less than or equal to 5%, the electron transport layer 15 and the hole injection layer 12 achieve a high degree of spatial consistency. This thickness matching facilitates the formation of uniform carrier transport channels within the device, avoiding localized current congestion or carrier accumulation, thereby balancing the injection and transport efficiency of electrons and holes, improving the device's luminous efficiency and operational stability, and extending the device's lifespan.

[0047] In some embodiments, the maximum thickness of the hole injection layer 12 can be 20nm, 30nm, 40nm, 60nm, 80nm, 90nm, 110nm, 130nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, etc.

[0048] By limiting the maximum thickness of the hole injection layer 12 to 20~200nm, it is ensured that the hole injection layer 12 can effectively reduce the work function of the anode 11 and promote hole injection, while avoiding the increase in device series resistance or deterioration of optical interference effect caused by an excessively thick hole injection layer 12. A thinner hole injection layer 12 is beneficial to reduce the device driving voltage and power consumption, while allowing the electron transport layer 15 to more closely match the morphology of the hole injection layer 12, further optimizing the overall optical and electrical performance of the device, and achieving a comprehensive improvement in high brightness, low power consumption and wide viewing angle.

[0049] The electron injection layer 16, electron transport layer 15, and cathode 17 are all formed using physical vapor deposition (PVD) technology. The surface contours (or geometry) of the electron injection layer 16, electron transport layer 15, and cathode 17 away from the anode 11 follow the curved structure of their preceding film layers.

[0050] For example, the surfaces of the electron injection layer 16, the electron transport layer 15, and the cathode 17 away from the anode 11 are all outwardly convex arc surfaces, and the curvature of the arc surfaces is the same.

[0051] By defining the surfaces of the electron injection layer 16, electron transport layer 15, and cathode 17 away from the anode 11 as outwardly convex arc surfaces with the same curvature, a uniform optical surface structure is formed at the external interface of the device. This structure facilitates consistent refraction and focusing of large-angle light emitted from the light-emitting layer 14 and transmitted through multiple layers, reducing light scattering or optical path disorder caused by interlayer curvature mismatch, thereby improving the emission efficiency of large-angle light and further improving the uniformity of the lateral viewing angle.

[0052] Furthermore, this uniform convex morphology, together with the asymmetric curvature electron transport layer 15 below, together constructs an optimized microcavity lens system, which enables small-angle light to be effectively focused and large-angle light to be effectively extracted. This improves the overall light extraction efficiency while maintaining the forward brightness of the device without attenuation, achieving a balance between high energy efficiency and wide viewing angle.

[0053] In some embodiments, the light-emitting diode 10 further includes a cover glass 18 (CPL), which is formed by physical vapor deposition, and the surface geometry of the cover glass 18 away from the anode 11 follows the curvature structure of its preceding film layer. The anode 11, hole injection layer 12, hole transport layer 13, light-emitting layer 14, electron transport layer 15, electron injection layer 16 and cathode 17 are stacked in sequence to form a combined structure, and the cover glass 18 is disposed on the light-emitting surface side of the combined structure.

[0054] In some embodiments, the light-emitting layer 14 has a third surface 141 and a fourth surface 142 disposed opposite to each other along the thickness direction of the anode 11, the third surface 141 being disposed on the side of the fourth surface 142 away from the anode 11; the third surface 141 is an outwardly convex arc surface, and the curvature of the third surface 141 is greater than the curvature of the fourth surface 142; wherein, the fourth surface 142 is a plane or an outwardly convex arc surface.

[0055] By defining the third surface 141 of the light-emitting layer 14 as an outwardly convex arc surface with a curvature greater than that of the fourth surface 142, the light-emitting layer 14 itself forms an asymmetric lens structure with specific optical focusing capabilities. This structure facilitates effective directional control of photons generated within the light-emitting layer 14, particularly by refracting light rays that originally propagate at large angles into rays closer to the vertical direction, thereby increasing the luminous flux emitted from the front of the device and improving the forward light extraction efficiency. Simultaneously, due to the higher curvature of the third surface 141, this geometry facilitates the divergence of large-angle light rays, resulting in a more uniform brightness distribution at lateral viewing angles and improving color shift and brightness attenuation issues at large viewing angles. Furthermore, this asymmetric curvature design can achieve consistent optical path control through morphological optimization of a single-layer material without introducing additional optical films, reducing color inhomogeneity caused by light interference and further improving the purity of the emitted color and the overall display effect of the device.

[0056] Please see Figure 1 , Figure 8 and Figure 9 , Figure 8 This is a schematic diagram of the structure of an embodiment of the anode provided in this application. Figure 9 This is a structural schematic diagram of the projected patterns of different anodes provided in this application. Among them, Figure 9 The parts shown in (c3), (c4) and (c5) represent the projected patterns of different anodes 11. Figure 8 In this context, 'a' represents the radius of curvature, and 'b' represents the diameter of anode 11.

[0057] The diameter of anode 11 is greater than or equal to 30 μm.

[0058] The surface of the anode 11 on the side away from the light-emitting layer 14 can be either curved or flat. For example, Figure 1 As shown, the surface of the anode 11 away from the light-emitting layer 14 is an outwardly convex arc surface; for example, as... Figure 8 As shown, the surface of the anode 11 away from the light-emitting layer 14 is planar.

[0059] In some embodiments, the anode 11 and the hole injection layer 12 are arranged in close contact with each other, and the surface of the anode 11 facing the hole injection layer 12 is a preset curved surface that is concave inward. The radius of curvature of the preset curved surface is 1.5mm to 41mm, and the diameter of the anode 11 is 30 to 180um.

[0060] The radius of curvature of the preset surface can be 1.5mm, 2.5mm, 3.5mm, 4.5mm, 5.0mm, 5.5mm, 7mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 39.5mm, 40mm, 40.5mm, 41mm, etc.

[0061] The diameter of anode 11 can be 30um, 40um, 50um, 70um, 90um, 120um, 150um, 160um, 170um, 180um, etc.

[0062] By defining the surface of the anode 11 facing the hole injection layer 12 as a pre-defined inwardly concave curved surface, the anode 11 itself possesses basic optical control capabilities, providing a non-planar film-forming substrate for the subsequently fabricated organic layer. The radius of curvature of this concave surface ranges from 1.5 mm to 41 mm, and combined with the anode 11 aperture of 30 micrometers to 180 micrometers, the formed hole injection layer 12 can be precisely constructed into an asymmetric lens structure with a specific focal length. This structure facilitates the optimization of the refraction and reflection path of large-angle light emitted from the light-emitting layer 14 at the anode 11 interface, allowing large-angle light that would otherwise easily undergo total internal reflection or scattering at the interface to be coupled and emitted more effectively, thereby improving light extraction efficiency. Simultaneously, the concave design of the anode 11 facilitates the uniform spreading and fixation of the ink in the hole injection layer 12, reducing droplet accumulation or edge effects caused by surface tension, resulting in a more stable and controllable film morphology. Furthermore, this specific combination of geometric parameters enables the device to improve the lateral viewing angle while avoiding the loss of forward light emission efficiency caused by traditional microlenses or optical films, thereby achieving synergistic optimization of high brightness and wide viewing angle and reducing product power consumption.

[0063] In some embodiments, the anode 11 forms an orthographic projection pattern on the plane of the light-emitting diode 10, the aspect ratio of the orthographic projection pattern is greater than 1, and the curvature direction of the preset surface is along the radial direction of the orthographic projection pattern; or the aspect ratio of the orthographic projection pattern is equal to 1, and the preset surface is a rotationally symmetric surface with the geometric center of the orthographic projection pattern as the valley bottom.

[0064] The aspect ratio of an orthographic projection graphic is the ratio of the dimension along the longest axis to the dimension along the shortest axis of the profile.

[0065] In some embodiments, a single light-emitting diode 10 constitutes a pixel of the display panel 1.

[0066] When the aspect ratio of the orthographic projection pattern is greater than 1, the orthographic projection pattern of the anode 11 is non-circular, such as elliptical, rectangular, elongated or irregular structure with rounded corners. At this time, the curvature direction of the preset surface is along the radial direction of the orthographic projection pattern. That is, the concave trend of the surface extends along the radial directions from the center of the pattern to the edge. For narrow and elongated pixels, this radial curvature is usually manifested as cylindrical curvature along the short axis, thereby forming an optical lens effect in the pixel width direction.

[0067] When the aspect ratio of the orthographic projection is equal to 1, the orthographic projection of anode 11 is a regular polygon or circle. At this time, the preset surface is a rotationally symmetric surface with the geometric center of the orthographic projection as the valley bottom, which means that the surface is axially symmetric about the center point, such as a spherical depression or a bowl-shaped structure.

[0068] By defining the aspect ratio and corresponding curvature direction of the orthographic projection pattern of the anode 11, the anode 11 structure can be customized for optical design based on the specific geometry of the pixel. When the aspect ratio is greater than 1, the radial curvature design allows the anode 11 to focus or diverge light in the short axis direction or a specific radial direction of the pixel, which is beneficial for optimizing the optical characteristics of narrow pixels, improving light extraction efficiency in this direction, and improving the lateral viewing angle. When the aspect ratio is equal to 1, the rotationally symmetric curved surface with the geometric center as the valley floor gives the anode 11 surface all-around symmetrical optical control capabilities, which is beneficial for forming a uniform light distribution, reducing viewing angle-dependent color difference, and improving the uniformity of displayed colors. This design, which matches specific curved surface structures to different projection shapes, allows the device to flexibly adapt to different pixel arrangements and display requirements, effectively widening the effective viewing angle range while maintaining high forward brightness, and improving the overall visual experience of the large-size display panel 1.

[0069] In some embodiments, the light-emitting diode 10 is an electroluminescent quantum dot device, a perovskite light-emitting diode, or an organic light-emitting diode.

[0070] In some embodiments, the light-emitting diode 10 is an electroluminescent quantum dot device. In the electroluminescent quantum dot device, the light-emitting layer 14 is composed of quantum dot materials, such as core-shell quantum dots like CdSe and InP, which are deposited on the hole transport layer 13 by inkjet printing and then dried under vacuum to form a thin film with a specific morphology.

[0071] In other embodiments, the light-emitting diode 10 is a perovskite light-emitting diode. In the perovskite light-emitting diode, the light-emitting layer 14 is composed of halide perovskite materials such as CsPbBr3, and is also prepared by solution processing. The crystallization process and surface morphology of the thin film are controlled by inkjet printing and vacuum drying.

[0072] In some other embodiments, the light-emitting diode 10 is an organic light-emitting diode. In an organic light-emitting diode, the light-emitting layer 14 is composed of small molecule or polymeric organic semiconductor materials, and is formed into a thin film structure with a specific curvature by inkjet printing.

[0073] By defining the light-emitting diode 10 as an electroluminescent quantum dot device, a perovskite light-emitting diode, or an organic light-emitting diode, this technical solution can be widely applied to current mainstream solution-based display device systems. For electroluminescent quantum dot devices, the excellent optical properties of quantum dot materials combined with thin film structures of specific morphologies are beneficial for further improving color purity and luminous efficiency. For perovskite light-emitting diodes, the high luminous quantum yield of perovskite materials, combined with curved structures, is beneficial for achieving high brightness and wide viewing angle display effects. For organic light-emitting diodes, the use of mature organic material systems and solution-based processes to achieve complex curved surface morphology control is beneficial for reducing manufacturing costs and increasing production capacity.

[0074] Please see Figure 1 and Figure 10 , Figure 10 This is a schematic diagram of the structure of an embodiment of the display panel provided in this application.

[0075] This application provides a display panel 1, which includes the above-mentioned light-emitting diode 10 and driving circuit 20. The driving circuit 20 is used to provide driving signals to the light-emitting diode 10.

[0076] The display panel 1 includes a pixel array area (not shown), which includes a plurality of pixels (not shown), each pixel including a light-emitting diode 10; and a driving circuit 20, which is disposed around the pixel array area or integrated on the display panel 1, for providing driving signals to the anode 11 of the pixel.

[0077] Please see Figure 1 and Figure 11 , Figure 11 This is a flowchart illustrating one embodiment of the light-emitting diode provided in this application.

[0078] This application provides a method for fabricating a light-emitting diode (LED), used to fabricate the aforementioned LED. The method for fabricating the LED includes: S1: Provides a substrate; S2: An anode, a hole injection layer, a hole transport layer, and a light-emitting layer are sequentially formed on a substrate, or a light-emitting layer, a hole transport layer, a hole injection layer, and an anode are sequentially formed; wherein, the two surfaces of the hole injection layer that are opposite each other along the thickness direction of the anode are both outwardly convex curved surfaces; the hole injection layer, the hole transport layer, and the light-emitting layer are all prepared by inkjet printing.

[0079] The substrate serves as the support platform for the entire device.

[0080] The use of inkjet printing to fabricate the hole injection layer, hole transport layer, and light-emitting layer enables precise control of the thin film morphology, resulting in specific curved surface structures at the interfaces of each layer. This improves light extraction efficiency at wide viewing angles, achieving a wide-viewing-angle display effect. Inkjet printing also makes the device fabrication process more flexible, reducing material waste and increasing production efficiency. Furthermore, by controlling the ink properties, the optical performance of each interface can be further optimized, allowing the device to maintain high brightness while improving viewing angle performance.

[0081] Compared to the limitations of traditional vapor deposition processes, such as shadowing effects, uneven step coverage, and multilayer morphology distortion caused by the linear deposition characteristics of small molecules, this application uses a solution method to prepare the functional layer of light-emitting diodes. By utilizing physical mechanisms such as liquid flow, wetting, surface tension, and drying shrinkage, the surface morphology of single-layer and multi-layer stacked films can be precisely controlled, avoiding the geometric passivation and distortion problems of vapor deposition.

[0082] Building upon this, this application directly integrates the optical modulation structure within the LED or adjacent to the light-emitting region, rather than placing an additional lens outside the device. This allows for the control of the light emission path during the light generation and initial propagation stages, offering two significant advantages: First, by reducing additional optical interfaces such as air / resin and resin / encapsulation layers, Fresnel reflection, scattering, and parasitic absorption losses are effectively reduced, improving the forward light emission efficiency while maintaining or even enhancing the lateral viewing angle. Second, it achieves coordinated optimization of "light emission-transmission-emission" within the pixel. Through the non-planar structure formed by the solution-based film layer following the anode curvature, the carrier transport path, recombination emission position, and light emission path are designed collaboratively in the same space. This improves the large-angle light extraction efficiency while maintaining carrier balance, thus balancing device efficiency, wide viewing angle performance, and lifetime stability.

[0083] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0084] The above are merely embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A light-emitting diode, characterized in that, It includes an anode, a hole injection layer, a hole transport layer, and a light-emitting layer stacked in sequence; The hole injection layer has two surfaces that are opposite each other along the thickness direction of the anode, both of which are outwardly convex curved surfaces.

2. The light-emitting diode according to claim 1, characterized in that, The hole injection layer has two surfaces disposed opposite to each other along the thickness direction of the anode, namely a first surface and a second surface, both of which are arc surfaces; the first surface is disposed on the side of the second surface away from the anode; The curvature of the first surface is less than the curvature of the second surface.

3. The light-emitting diode according to claim 2, characterized in that, The light-emitting diode further includes an electron transport layer, an electron injection layer, and a cathode stacked sequentially. The electron transport layer is disposed on the side of the electron injection layer closest to the anode. The surface of the electron transport layer away from the anode is an outwardly convex arc surface, and the surface of the electron transport layer close to the anode is an inwardly concave arc surface. The relative deviation between the maximum thickness of the electron transport layer and the maximum thickness of the hole injection layer is less than or equal to 5%, and the relative deviation between the edge thickness of the electron transport layer and the edge thickness of the hole injection layer is less than or equal to 5%; and / or, the maximum thickness of the hole injection layer is 20~200nm.

4. The light-emitting diode according to claim 3, characterized in that, The electron injection layer, the electron transport layer, and the cathode surfaces away from the anode are all outwardly convex arc surfaces, and the curvature of the arc surfaces is the same.

5. The light-emitting diode according to claim 2, characterized in that, The light-emitting layer has a third surface and a fourth surface disposed opposite to each other along the thickness direction of the anode, the third surface being disposed on the side of the fourth surface away from the anode; the third surface is an outwardly convex arc surface, and the curvature of the third surface is greater than the curvature of the fourth surface; wherein, the fourth surface is a plane or an outwardly convex arc surface.

6. The light-emitting diode according to claim 2, characterized in that, The anode and the hole injection layer are positioned in close contact on their respective surfaces, and the surface of the anode facing the hole injection layer is a pre-defined curved surface that is concave inward. The radius of curvature of the pre-defined curved surface is 1.5 mm to 41 mm, and the diameter of the anode is 30 to 180 μm.

7. The light-emitting diode according to claim 6, characterized in that, The anode forms an orthographic projection pattern in the plane of the light-emitting diode, the aspect ratio of the orthographic projection pattern is greater than 1, and the curvature direction of the preset surface is along the radial direction of the orthographic projection pattern; or the aspect ratio of the orthographic projection pattern is equal to 1, and the preset surface is a rotationally symmetric surface with the geometric center of the orthographic projection pattern as the valley bottom.

8. The light-emitting diode according to claim 1, characterized in that, The light-emitting diode is an electroluminescent quantum dot device, a perovskite light-emitting diode, or an organic light-emitting diode.

9. A method for fabricating a light-emitting diode (LED), used to fabricate the LED according to any one of claims 1 to 8, characterized in that, include: Provide a base; An anode, a hole injection layer, a hole transport layer, and a light-emitting layer are sequentially formed on the substrate, or the light-emitting layer, the hole transport layer, the hole injection layer, and the anode are sequentially formed; wherein, the two surfaces of the hole injection layer that are arranged opposite each other along the thickness direction of the anode are both outwardly convex curved surfaces; the hole injection layer, the hole transport layer, and the light-emitting layer are all prepared by inkjet printing.

10. A display panel, characterized in that, The invention includes a light-emitting diode and a driving circuit as described in any one of claims 1 to 8, wherein the driving circuit is used to provide a driving signal to the light-emitting diode.

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