Display panel capable of improving light extraction rate and preparation method thereof

Abstract

The invention provides a display panel capable of improving light extraction rate and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The display panel comprises a light-emitting functional layer, a driving substrate and a light extraction structure, the light-emitting functional layer is located on the driving substrate and electrically connected with the driving substrate, and the light-emitting functional layer comprises a plurality of light-emitting units arranged at intervals; the light extraction structures are located on the side, away from the driving substrate, of the light-emitting functional layer, the light extraction structures correspond to the light-emitting units one to one, and orthographic projections of the light-emitting units on the surface of the driving substrate are located in orthographic projections of the corresponding light extraction structures on the surface of the driving substrate; the surface of the end, away from the driving substrate, of the light taking structure is an arc face, and the arc face is a roughened face. According to the embodiment of the invention, the problem that large-angle emergent light is easily reflected back to the inside by the light extraction structure can be improved, and the light extraction rate of the light extraction structure is improved.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a display panel with improved light extraction efficiency and a method for its fabrication. Background Technology

[0002] Micro LED (Micro Light Emitting Diode) display panels are a display technology that uses micron-sized LED chips as self-emissive pixels. It integrates millions of Micro LED chips onto a driving substrate using mass transfer technology, enabling independent light control for each pixel.

[0003] In related technologies, display panels typically include a driving substrate and multiple light-emitting chips arranged in an array on the driving substrate. Each light-emitting chip also has a hemispherical light-collecting structure, which is used to converge the emitted light into parallel rays to enhance the brightness of the light-emitting chip.

[0004] Because Micro LED light is emitted irregularly, when the emission angle is greater than a certain angle, the light will not be able to escape and will be completely reflected back into the interior. The light-collecting structure in related technologies can collimate some of the light emitted at small angles, but it is difficult for the light-collecting structure to effectively collect light at large angles, thereby reducing the light energy utilization rate. Summary of the Invention

[0005] This disclosure provides a display panel with improved light extraction efficiency and its manufacturing method, which can improve the problem of large-angle emitted light being easily reflected back into the interior by the light-collecting structure, thereby increasing the light extraction efficiency of the light-collecting structure. The technical solution is as follows:

[0006] On one hand, this disclosure provides a display panel, which includes: a light-emitting functional layer, a driving substrate, and a light-harvesting structure. The light-emitting functional layer is located on the driving substrate and electrically connected to the driving substrate. The light-emitting functional layer includes a plurality of light-emitting units arranged at intervals. The light-harvesting structure is located on the side of the light-emitting functional layer away from the driving substrate. The light-harvesting structure corresponds one-to-one with the light-emitting units. The orthographic projection of the light-emitting unit on the surface of the driving substrate is located within the orthographic projection of the corresponding light-harvesting structure on the surface of the driving substrate. The surface of the end of the light-harvesting structure away from the driving substrate is an arc surface, and the arc surface is a roughened surface.

[0007] In one implementation of this disclosure, the ratio of the surface roughness of the roughened surface to the wavelength of the emitted light from the light-emitting unit is 0.5 to 1.

[0008] In another implementation of this disclosure, the orthographic projection of the light-emitting surface of the light-emitting unit away from the driving substrate onto the surface of the driving substrate lies within the orthographic projection of the arc surface onto the surface of the driving substrate.

[0009] In another implementation of this disclosure, the light-collecting structure includes a plurality of light-emitting layers stacked sequentially along a direction away from the driving substrate, wherein the refractive index of the light-emitting layers decreases in the stacking direction.

[0010] In another implementation of this disclosure, in two adjacent light-emitting layers, the latter light-emitting layer encloses the former light-emitting layer.

[0011] In another implementation of this disclosure, the surface of the roughened surface has a plurality of protrusions and a plurality of grooves arranged at intervals, wherein the protrusions and the grooves are all pyramidal in shape.

[0012] In another implementation of this disclosure, the display panel further includes an insulating layer and a transparent conductive layer. The insulating layer is located on the driving substrate and covers the light-emitting units. The insulating layer has vias that expose each of the light-emitting units. The transparent conductive layer is located on the surface of the insulating layer and is connected to each of the light-emitting units through the vias.

[0013] In another implementation of this disclosure, the display panel further includes a connecting electrode located on the surface of the transparent conductive layer and in the gap between each of the light-emitting units.

[0014] In another implementation of this disclosure, the display panel further includes a plurality of bonding metal blocks corresponding one-to-one with the light-emitting units, the bonding metal blocks being located on the driving substrate, and each light-emitting unit being located on the corresponding bonding metal block; the orthographic projection of the light-emitting unit on the surface of the driving substrate is located within the orthographic projection of the corresponding bonding metal block on the surface of the driving substrate.

[0015] Secondly, embodiments of this disclosure provide a method for fabricating a display panel, the method comprising: forming a light-emitting functional layer on a substrate; bonding the light-emitting functional layer to a driving substrate and removing the substrate to electrically connect the light-emitting functional layer to the driving substrate; patterning the light-emitting functional layer to form a plurality of spaced light-emitting units; forming a light-collecting structure on the side of the light-emitting functional layer away from the driving substrate, the light-collecting structure corresponding one-to-one with the light-emitting units, the orthographic projection of the light-emitting unit on the surface of the driving substrate being located within the orthographic projection of the corresponding light-collecting structure on the surface of the driving substrate; the surface of the end of the light-collecting structure away from the driving substrate being an arc surface, and the arc surface being a roughened surface.

[0016] The beneficial effects of the technical solutions provided in this disclosure include at least the following:

[0017] The display panel provided in this embodiment has a curved surface at the top of the light-collecting structure. As a basic optical element, the curved surface has the characteristic of converging light. The curved surface can apply an initial deflection to the emitted light from the light-emitting unit, so that the originally dispersed light is concentrated in a more favorable direction.

[0018] Simultaneously, the curved surface is roughened. This roughening introduces a secondary scattering interface between the light-emitting unit and large-angle light rays by creating numerous randomly or regularly distributed micro-undulations. When large-angle light rays strike this interface, the originally single reflection path is broken. The light rays undergo multiple scattering or refraction at the uneven structure of the roughened surface. Each interaction can alter the original propagation direction, causing some light rays with incident angles greater than the critical angle to be broken into multiple sub-paths satisfying the condition of less than the critical angle, thus gaining the opportunity to escape to the outside. Furthermore, the randomness of the roughened surface avoids the specific angle reflection loss that may occur with traditional regular structures, further improving the omnidirectional capture capability for non-directional large-angle light.

[0019] In this embodiment, the designed light-harvesting structure with curved surface focusing and roughened surface active scattering not only retains the collimation optimization for small-angle light, but also specifically solves the problem of large-angle light escape, reduces the light energy loss due to total internal reflection, and ultimately improves the overall light extraction efficiency of the light-emitting unit. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure, 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 disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a display panel provided in an embodiment of this disclosure;

[0022] Figure 2 This is a schematic diagram of a light-collecting structure provided in an embodiment of this disclosure;

[0023] Figure 3 This is a flowchart of a method for manufacturing a display panel according to an embodiment of this disclosure;

[0024] Figure 4 This is a manufacturing state diagram of a display panel provided in an embodiment of this disclosure;

[0025] Figure 5This is a manufacturing state diagram of a display panel provided in an embodiment of this disclosure.

[0026] The markings in the diagram are explained as follows:

[0027] 10. Light-emitting functional layer; 100. Light-emitting unit;

[0028] 11. First semiconductor layer; 12. Multiple quantum well layer; 13. Second semiconductor layer;

[0029] 20. Driving substrate;

[0030] 30. Light-collecting structure; 31. Roughened surface; 301. Light-emitting layer;

[0031] 40. Insulation layer;

[0032] 50. Transparent conductive layer;

[0033] 60. Connect the electrodes;

[0034] 70. Substrate; 71. Contact layer; 72. Bonding metal block; 73. Bonding metal layer. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0036] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0037] Figure 1 This is a schematic diagram of the structure of a display panel provided in an embodiment of this disclosure. Figure 1As shown, the display panel includes: a light-emitting functional layer 10, a driving substrate 20 and a light-collecting structure 30. The light-emitting functional layer 10 is located on the driving substrate 20 and is electrically connected to the driving substrate 20. The light-emitting functional layer 10 includes a plurality of light-emitting units 100 arranged at intervals.

[0038] like Figure 1 As shown, the light-collecting structure 30 is located on the side of the light-emitting functional layer 10 away from the driving substrate 20. The light-collecting structure 30 corresponds one-to-one with the light-emitting unit 100. The orthographic projection of the light-emitting unit 100 on the surface of the driving substrate 20 is located within the orthographic projection of the corresponding light-collecting structure on the surface of the driving substrate 20.

[0039] like Figure 1 As shown, the surface of the light-collecting structure 30 at the end away from the driving substrate 20 is an arc surface, and the arc surface is a roughened surface 31.

[0040] The display panel provided in this embodiment has a curved surface at the top of the light-collecting structure 30. As a basic optical element, the curved surface has the characteristic of converging light. The curved surface can apply an initial deflection to the emitted light of the light-emitting unit 100, so that the originally dispersed light is concentrated in a more favorable direction.

[0041] Simultaneously, the curved surface is roughened into a surface 31. This roughened surface 31, by forming numerous randomly or regularly distributed microscopic undulations, introduces a secondary scattering interface between the light-emitting unit 100 and large-angle light rays. When large-angle light rays strike this interface, the originally single reflection path is broken. The light rays undergo multiple scattering or refraction at the uneven structure of the roughened surface 31. Each interaction may change its original propagation direction, causing some light rays with an incident angle greater than the critical angle to be broken into multiple sub-paths satisfying the condition of an angle less than the critical angle, thus gaining the opportunity to escape to the outside. Furthermore, the randomness of the roughened surface 31 avoids the specific angle reflection loss that may occur with traditional regular structures, further improving the omnidirectional capture capability for non-directional large-angle light.

[0042] In this embodiment, the light-collecting structure 30 with arc-shaped basic focusing and roughened surface 31 active scattering not only retains the collimation optimization for small-angle light, but also specifically solves the problem of large-angle light escape, reduces the light energy loss due to total internal reflection, and ultimately improves the overall light extraction efficiency of the light-emitting unit 100.

[0043] Alternatively, the light-collecting structure 30 can be made of PDMS, PMMA, or silicon dioxide.

[0044] Polydimethylsiloxane (PDMS) is a flexible and bendable material; its light transmittance exceeds 90%, which reduces total reflection and makes it suitable for flexible Micro LED panels.

[0045] Among them, polymethyl methacrylate (PMMA) has a light transmittance of over 92%, good optical uniformity, moderate mechanical strength, good weather resistance, and is easy to mold, making it suitable for preparing light-collecting structures for large-area planar displays 30.

[0046] Among them, silicon dioxide has a light transmittance of over 95% and excellent thermal stability, and can be precisely processed into microstructures through etching, making it suitable for high-temperature processes and high-precision display requirements.

[0047] Optionally, the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 is 0.5 to 1.

[0048] The surface roughness of roughened surface 31 can be the profile arithmetic mean deviation Ra, where Ra represents the arithmetic mean of the absolute values ​​of the distances from each point on the profile to the baseline within the sampling length.

[0049] Since the emitted light from the light-emitting unit 100 contains multiple wavelength components, such as blue light with wavelengths of approximately 450 nm to 480 nm and green light with wavelengths of approximately 520 nm to 560 nm, when the roughness of the roughened surface 31 is on the same order of magnitude as the light wavelength, such as when the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 is 0.5 to 1, the size of the micro-uneven structure is similar to the light wavelength, which can produce Rayleigh scattering or Mie scattering effects on the light. This scattering can specifically act on large-angle emitted light, and through multiple reflections / refractions at the uneven interface, the light that was originally trapped by total internal reflection is decomposed into multiple sub-light paths that satisfy the condition of less than the critical angle, thereby increasing the probability of the light escaping to the outside.

[0050] If the roughness is much greater than the wavelength, the uneven structure becomes too pronounced, causing multiple disordered reflections or even absorptions of light at the interface, which reduces the overall transmission efficiency. However, by controlling the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 within the aforementioned range, effective control of large-angle light can be ensured while avoiding excessive energy loss from scattering, thus achieving an optimal balance between scattering gain and transmission loss.

[0051] Since the emitted light from an LED typically covers a certain wavelength range, such as the blue-green light band, the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 within the aforementioned range can cover the scattering requirements of most wavelengths within that range.

[0052] For example, for shorter wavelength blue light (e.g., 460 nm), the roughness is designed to be 230 nm to 460 nm.

[0053] For example, for longer wavelength green light (e.g., 530 nm), the roughness is designed to be between 265 nm and 530 nm. This ensures that light of different wavelengths can be enhanced by scattering through a similarly sized uneven structure, thereby improving the full-spectrum light extraction efficiency.

[0054] As an example, the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 is 0.8. The center wavelength of the green light emitted by the light-emitting unit 100 is 530nm. When the roughness of the roughened surface 31 is designed to be 424nm (the ratio of the surface roughness of the roughened surface 31 to the wavelength of the emitted light from the light-emitting unit 100 = 424 / 530≈0.8), the micro-uneven structure at the 424nm scale can reflect or refract the 530nm green light, deflecting it to a smaller angle so that it meets the escape condition.

[0055] Optionally, such as Figure 1 As shown, the orthographic projection of the light-emitting surface of the light-emitting unit 100 away from the driving substrate 20 onto the surface of the driving substrate 20 is located within the orthographic projection of the arc surface onto the surface of the driving substrate 20.

[0056] In this case, the orthographic projection of the light-emitting surface of the light-emitting unit 100 is completely covered by the orthographic projection of the curved surface, ensuring that the light emitted from the center or edge of the light-emitting unit 100 can directly illuminate the roughened curved surface structure, thus avoiding the light from scattering or being lost due to exceeding the light-collecting range.

[0057] Furthermore, the complete inclusion relationship of the orthographic projection ensures that the light emitted from each region of the light-emitting unit 100 can be processed by the curved surface and the roughened structure, avoiding uneven brightness caused by local light not contacting the light-collecting structure 30, and ultimately enhancing the uniformity and brightness consistency of the overall light emission.

[0058] Figure 2 This is a schematic diagram of a light-collecting structure 30 provided in an embodiment of this disclosure. Figure 2 As shown, the light-collecting structure 30 includes a plurality of light-emitting layers 301 stacked sequentially in a direction away from the driving substrate 20, and the refractive index of the light-emitting layers 301 decreases in the stacking direction.

[0059] When light travels directly from the light-emitting unit 100 (high refractive index) to the air (low refractive index), total internal reflection is likely to occur at the interface due to the abrupt change in refractive index. The multilayer light-escape layer 301 reduces the refractive index layer by layer, which is equivalent to building a refractive index slope for the light. This causes the incident angle of the light at each layer interface to gradually decrease, making it easier to meet the escape condition of less than the critical angle, thereby reducing the total internal reflection loss.

[0060] Optionally, the refractive index of the light-emitting layer 301 near the light-emitting unit 100 can be 2 to 2.5, forming a high refractive index layer to reduce interface reflection with the light-emitting unit 100; the refractive index of the middle light-emitting layer 301 can be 1.5 to 1.8, which can further adjust the direction of light; the refractive index of the outermost light-emitting layer 301 can be below 1.3, forming a low refractive index layer with a refractive index close to that of air, so that the incident angle of the final emitted light is closer to vertical, thereby improving the transmittance.

[0061] For example, the first light-emitting layer 301 that is close to the light-emitting unit 100 can be a silicon nitride layer with a refractive index of about 2.0 and a thickness of 100 nm. When the light-emitting chip is a GaN chip, the refractive index is about 2.5. Matching the refractive indices of the two can reduce interface reflection.

[0062] The second light-emitting layer 301 can be a silicon dioxide layer with a refractive index of about 1.5 and a thickness of 200 nm, which can buffer the medium refractive index.

[0063] The third light-emitting layer 301 can be a magnesium fluoride layer with a refractive index of about 1.38 and a thickness of 300 nm, which is close to the refractive index of air, making it easier for light to escape.

[0064] Optionally, such as Figure 2 As shown, in two adjacent light-emitting layers 301, the latter light-emitting layer 301 wraps around the former light-emitting layer 301.

[0065] In the above implementation, by completely enveloping the previous layer in a stacking manner, it is ensured that there are no gaps or air bubbles between adjacent light-escape layers 301, thus preventing a decrease in escape efficiency due to abrupt changes in refractive index or scattering loss at the interlayer gaps. The tight encapsulation structure keeps the light in a continuous refractive index gradient medium at all times, reducing energy loss in the propagation path.

[0066] Meanwhile, the encapsulation structure makes the decrease in refractive index of the multi-layered light-escape layer 301 smoother, and the scattering / refraction of light at each layer interface is more consistent, increasing the probability of escape.

[0067] Furthermore, the coating of the next layer can fix the position of the previous layer, prevent the film from falling off or deforming, ensure the long-term reliability of the refractive index gradient, and maintain the stability of the light extraction efficiency.

[0068] Optionally, such as Figure 2 As shown, the surface of the roughened surface 31 has multiple protrusions and multiple grooves arranged at intervals, and both the protrusions and grooves are pyramidal in shape.

[0069] By designing the surface structure of the roughened surface 31 as pyramidal protrusions and pyramidal grooves, multiple reflection / refraction interfaces at specific angles are formed using the inclined surfaces of the pyramids. When light emitted at a large angle strikes the inclined surfaces, its propagation direction is forcibly changed to an angle closer to parallel or smaller than the critical angle, thereby increasing the probability of light escape. Compared to a circular arc surface, the directional scattering of the pyramid is more effective at breaking total internal reflection.

[0070] The raised pyramids and adjacent recessed pyramids are arranged in an alternating pattern, and the light undergoes multiple reflections / refractions in the complex path, which further reduces the incident angle and improves the efficiency of light extraction from all angles.

[0071] Optionally, such as Figure 1 As shown, the display panel also includes an insulating layer 40 and a transparent conductive layer 50. The insulating layer 40 is located on the driving substrate 20 and covers the light-emitting unit 100. The insulating layer 40 has through holes that expose each light-emitting unit 100.

[0072] like Figure 1 As shown, the transparent conductive layer 50 is located on the surface of the insulating layer 40 and is connected to each light-emitting unit 100 through a via.

[0073] In the above implementation, the insulating layer 40 covers the light-emitting unit 100, which can effectively achieve electrical isolation between adjacent light-emitting units 100 and between the light-emitting unit 100 and other film layers, prevent short circuit faults between different circuits, protect the light-emitting unit 100 and the driving circuit from external interference and damage, and improve the stability and reliability of the display panel operation.

[0074] Meanwhile, the via design on the insulating layer 40 is precise, exposing only each light-emitting unit 100. The transparent conductive layer 50 is connected to the light-emitting unit 100 through the via, which can realize the precise electrical connection between the light-emitting unit 100 and the driving circuit, ensuring that each light-emitting unit 100 can receive the driving signal independently and stably, thus guaranteeing the accuracy and consistency of the display effect.

[0075] For example, the transparent conductive layer 50 may be an ITO layer or an IZO layer.

[0076] As an example, the thickness of the transparent conductive layer 50 can be greater than or equal to 2000 angstroms. This thickness range ensures good conductivity for effective transmission of electrical signals while also providing high transparency to reduce obstruction of the light emitted by the light-emitting unit 100.

[0077] For example, the insulating layer 40 may include at least one of a silicon oxide layer, a titanium oxide layer, and an epoxy resin layer.

[0078] For example, the insulating layer 40 can be a distributed Bragg reflector (DBR) layer.

[0079] The DBR layer may include multiple alternating layers of first material and multiple layers of second material, with different refractive indices for the first and second material layers.

[0080] For example, one of the first material layer and the second material layer is a TiO2 layer, and the other of the first material layer and the second material layer is a SiO2 layer.

[0081] Among them, the reflection band of the DBR has wavelength selectivity, which can accurately reflect light while allowing other stray wavelengths to pass through, thus enhancing the directional output of effective light.

[0082] For example, the thickness of the insulating layer 40 is 1.5 μm to 2.5 μm.

[0083] Optionally, such as Figure 1 As shown, the display panel also includes a connecting electrode 60, which is located on the surface of the transparent conductive layer 50 and in the gap between each light-emitting unit 100.

[0084] The connecting electrode 60 can establish additional electrical connection channels in the gaps between the light-emitting units 100, which facilitates the effective connection of multiple light-emitting units 100 or light-emitting units 100 in different regions, expands the flexibility of circuit connection, helps to realize complex display driving circuit layout, and meets diverse display needs.

[0085] Meanwhile, by rationally distributing electrical signals through the connecting electrode 60, each light-emitting unit 100 can obtain a more balanced driving current, reducing brightness differences caused by uneven current distribution, thereby improving the display uniformity of the entire display panel.

[0086] Furthermore, by utilizing the gaps between the light-emitting units 100 to set the connecting electrodes 60, the main display space of the display panel is not occupied additionally, thus avoiding the compression of the display area caused by adding connecting structures. This helps to achieve miniaturization and high pixel density design of the display panel and improves space utilization efficiency.

[0087] Optionally, such as Figure 1 As shown, the display panel also includes a plurality of bonding metal blocks 72 corresponding one-to-one with the light-emitting units 100. The bonding metal blocks 72 are located on the driving substrate 20, and each light-emitting unit 100 is located on the corresponding bonding metal block 72.

[0088] like Figure 1 As shown, the orthographic projection of the light-emitting unit 100 on the surface of the driving substrate 20 is located within the orthographic projection of the corresponding bonding metal block 72 on the surface of the driving substrate 20.

[0089] In the above implementation, the orthographic projection of the light-emitting unit 100 is located within the bonding metal block 72, ensuring precise alignment during bonding and preventing misalignment. The bonding metal block 72 provides a large contact area, enhancing the mechanical fixing strength between the light-emitting unit 100 and the driving substrate 20, preventing loosening or detachment after long-term use. Furthermore, the bonding metal block 72 directly supports the light-emitting unit 100, effectively reducing contact resistance, improving driving current transmission efficiency, reducing signal attenuation and heat generation, and ensuring stable driving and efficient light emission of the light-emitting unit 100.

[0090] Optionally, such as Figure 1 As shown, each light-emitting unit 100 includes a first semiconductor layer 11, a multiple quantum well layer 12, and a second semiconductor layer 13 stacked sequentially.

[0091] In this embodiment of the present disclosure, one of the first semiconductor layer 11 and the second semiconductor layer 13 is a p-type layer, and the other of the first semiconductor layer 11 and the second semiconductor layer 13 is an n-type layer.

[0092] As an example, the first semiconductor layer 11 is an n-type layer and the second semiconductor layer 13 is a p-type layer.

[0093] Optionally, the first semiconductor layer 11 is an n-type GaN layer. The thickness of the n-type GaN layer can be from 0.5 μm to 1 μm.

[0094] Optionally, the multiple quantum well layer 12 includes alternating InGaN quantum well layers and GaN quantum barrier layers. Specifically, the multiple quantum well layer 12 may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0095] As an example, in an embodiment of this disclosure, the multi-quantum-well layer 12 includes five alternating stacked InGaN quantum-well layers and GaN quantum-barrier layers.

[0096] Optionally, the thickness of the multiple quantum well layer 12 can be from 150 nm to 200 nm.

[0097] Optionally, the second semiconductor layer 13 is a p-type GaN layer. The thickness of the p-type GaN layer can be from 0.5 μm to 1 μm.

[0098] Optionally, such as Figure 1 As shown, the display panel also includes a contact layer 71, which is located on the surface of the light-emitting unit 100 near the driving substrate 20. The contact layer 71 of each light-emitting unit 100 is connected to the bonding metal block 72.

[0099] For example, the contact layer 71 may be at least one of a metal layer and a transparent conductive layer 50.

[0100] For example, contact layer 71 can be an ITO layer or an IZO layer.

[0101] Optionally, the driving substrate 20 may be a complementary metal-oxide-semiconductor (CMOS) integrated circuit board.

[0102] like Figure 1 As shown, an electrode block corresponding to each light-emitting unit 100 is provided on the driving substrate 20. Each light-emitting unit 100 has a bonding metal block 72 on the side near the driving substrate 20. The bonding metal block 72 of each light-emitting diode is electrically connected to the corresponding electrode block, so as to realize the purpose of the driving substrate 20 controlling the operation of each light-emitting diode.

[0103] For example, the bonding metal block 72 may include at least one of AuBe layer, Au layer, Ti layer, Ni layer and Pt layer.

[0104] Figure 3 This is a flowchart illustrating a method for manufacturing a display panel according to an embodiment of this disclosure. Figure 3 As shown, the preparation method includes:

[0105] S11: A light-emitting functional layer 10 is formed on the substrate 70.

[0106] For example, the substrate 70 is a sapphire substrate 70. The sapphire substrate 70 has high light transmittance, that is, the substrate 70 is a transparent substrate 70. In addition, sapphire material is relatively hard and has relatively stable chemical properties, which enables the light-emitting diode to have good light-emitting effect and stability.

[0107] For example, such as Figure 4 As shown, the light-emitting functional layer 10 may include a first semiconductor layer 11, a multiple quantum well layer 12, and a second semiconductor layer 13 sequentially stacked on the substrate 70.

[0108] The first semiconductor layer 11 has a first conductivity type, the second semiconductor layer 13 has a second conductivity type different from the first conductivity type, and the multi-quantum well layer 12 is used to generate light through electron-hole recombination.

[0109] Among them, one of the first semiconductor layer 11 and the second semiconductor layer 13 is a p-type layer, and the other of the first semiconductor layer 11 and the second semiconductor layer 13 is an n-type layer.

[0110] As an example, the first semiconductor layer 11 is an n-type layer and the second semiconductor layer 13 is a p-type layer.

[0111] Optionally, the first semiconductor layer 11 is an n-type GaN layer. The thickness of the n-type GaN layer can be from 0.5 μm to 1 μm.

[0112] Optionally, the multiple quantum well layer 12 includes alternating InGaN quantum well layers and GaN quantum barrier layers. Specifically, the multiple quantum well layer 12 may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0113] As an example, in an embodiment of this disclosure, the multi-quantum-well layer 12 includes five alternating stacked InGaN quantum-well layers and GaN quantum-barrier layers.

[0114] Optionally, the thickness of the multiple quantum well layer 12 can be from 150 nm to 200 nm.

[0115] Optionally, the second semiconductor layer 13 is a p-type GaN layer. The thickness of the p-type GaN layer can be from 0.5 μm to 1 μm.

[0116] After growing the light-emitting functional layer 10 in step S11, the process may further include growing a contact layer 71 on the surface of the light-emitting functional layer 10.

[0117] For example, the contact layer 71 may be at least one of a metal layer and a transparent conductive layer 50.

[0118] For example, contact layer 71 can be an ITO layer or an IZO layer.

[0119] S12: Bond the light-emitting functional layer 10 to the driving substrate 20 and remove the substrate 70 to make the light-emitting functional layer 10 electrically connected to the driving substrate 20.

[0120] like Figure 4 As shown, step S12 may include: forming a bonding metal layer 73 on the surface of both the driving substrate 20 and the contact layer 71, and bonding the contact layer 71 and the driving substrate 20 together.

[0121] The bonding metal layer 73 may include at least one of a titanium layer, a platinum layer, a gold layer, an aluminum layer, and a tin layer.

[0122] Next, as Figure 4 As shown, the substrate 70 is removed, and part of the surface light-emitting functional layer 10 is removed by etching or other means.

[0123] S13: Graphical processing of the light-emitting functional layer 10 to form multiple spaced light-emitting units 100.

[0124] like Figure 5 As shown, step S13 may include: forming a contact conductive layer on the surface of the light-emitting functional layer 10, then performing an array etching of the light-emitting units 100 to remove the non-patterned areas of the light-emitting functional layer 10 to form a plurality of light-emitting units 100, and etching the bonding metal layer 73 to form a plurality of bonding metal blocks 72.

[0125] For example, such as Figure 5 As shown, the graphically processed light-emitting functional layer 10 includes multiple trapezoidal light-emitting units 100.

[0126] The following steps may also be included before step S14:

[0127] like Figure 5 As shown, an insulating layer 40 is formed on the surface of the driving substrate 20, such that the insulating layer 40 covers each light-emitting unit 100; then the insulating layer 40 on the top of the light-emitting unit 100 is cut open to form a through hole exposing the light-emitting unit 100.

[0128] For example, the insulating layer 40 may be at least one of a silicon oxide layer, a titanium oxide layer, and an epoxy resin layer.

[0129] For example, the insulating layer 40 may be a plurality of alternating layers of silicon oxide and a plurality of layers of titanium oxide to form a distributed Bragg mirror layer.

[0130] For example, the thickness of the insulating layer 40 is 1.5 μm to 2.5 μm.

[0131] like Figure 5 As shown, the insulating layer 40 is covered with a transparent conductive layer 50.

[0132] The transparent conductive layer 50 is disposed on top of the insulating layer 40, and the transparent conductive layer 50 is electrically connected to each light-emitting unit 100 through through holes.

[0133] For example, the thickness of the transparent conductive layer 50 is greater than or equal to 2000 angstroms.

[0134] like Figure 5 As shown, a connecting electrode 60 is formed on the surface of the transparent conductive layer 50, and the connecting electrode 60 is located in the gap between each light-emitting unit 100.

[0135] S14: A light-collecting structure 30 is formed on the side of the light-emitting functional layer 10 away from the driving substrate 20.

[0136] like Figure 1 As shown, the light-collecting structure 30 corresponds one-to-one with the light-emitting unit 100. The orthographic projection of the light-emitting unit 100 on the surface of the driving substrate 20 is located within the orthographic projection of the corresponding light-collecting structure on the surface of the driving substrate 20. The surface of the end of the light-collecting structure 30 away from the driving substrate 20 is an arc surface, and the arc surface is a roughened surface 31.

[0137] Alternatively, the light-collecting structure 30 can be made of PDMS, PMMA, or silicon dioxide.

[0138] The display panel prepared by the preparation method provided in this embodiment has an arc surface at the top of the light-collecting structure 30. As a basic optical element, the arc surface has the characteristic of converging light. The arc surface can apply an initial deflection to the emitted light of the light-emitting unit 100, so that the originally dispersed light is concentrated in a more favorable direction.

[0139] Simultaneously, the curved surface is roughened into a surface 31. This roughened surface 31, by forming numerous randomly or regularly distributed microscopic undulations, introduces a secondary scattering interface between the light-emitting unit 100 and large-angle light rays. When large-angle light rays strike this interface, the originally single reflection path is broken. The light rays undergo multiple scattering or refraction at the uneven structure of the roughened surface 31. Each interaction may change its original propagation direction, causing some light rays with an incident angle greater than the critical angle to be broken into multiple sub-paths satisfying the condition of an angle less than the critical angle, thus gaining the opportunity to escape to the outside. Furthermore, the randomness of the roughened surface 31 avoids the specific angle reflection loss that may occur with traditional regular structures, further improving the omnidirectional capture capability for non-directional large-angle light.

[0140] In this embodiment, the light-collecting structure 30 with arc-shaped basic focusing and roughened surface 31 active scattering not only retains the collimation optimization for small-angle light, but also specifically solves the problem of large-angle light escape, reduces the light energy loss due to total internal reflection, and ultimately improves the overall light extraction efficiency of the light-emitting unit 100.

[0141] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. The data therein represents only illustrative examples. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A display panel, characterized in that, The display panel includes: a light-emitting functional layer (10), a driving substrate (20) and a light-collecting structure (30). The light-emitting functional layer (10) is located on the driving substrate (20) and is electrically connected to the driving substrate (20). The light-emitting functional layer (10) includes a plurality of light-emitting units (100) arranged at intervals. The light-collecting structure (30) is located on the side of the light-emitting functional layer (10) away from the driving substrate (20). The light-collecting structure (30) corresponds one-to-one with the light-emitting unit (100). The orthographic projection of the light-emitting unit (100) on the surface of the driving substrate (20) is located within the orthographic projection of the corresponding light-collecting structure on the surface of the driving substrate (20). The surface of the light-collecting structure (30) at the end away from the driving substrate (20) is an arc surface, and the arc surface is a roughened surface (31).

2. The display panel according to claim 1, characterized in that, The ratio of the surface roughness of the roughened surface (31) to the wavelength of the emitted light from the light-emitting unit (100) is 0.5 to 1.

3. The display panel according to claim 1, characterized in that, The orthographic projection of the light-emitting surface of the light-emitting unit (100) away from the driving substrate (20) onto the surface of the driving substrate (20) is located within the orthographic projection of the arc surface onto the surface of the driving substrate (20).

4. The display panel according to claim 1, characterized in that, The light-collecting structure (30) includes a plurality of light-emitting layers (301) stacked sequentially in a direction away from the driving substrate (20), wherein the refractive index of the light-emitting layers (301) decreases in the stacking direction.

5. The display panel according to claim 4, characterized in that, In two adjacent light-emitting layers (301), the latter light-emitting layer (301) wraps around the former light-emitting layer (301).

6. The display panel according to any one of claims 1 to 5, characterized in that, The roughened surface (31) has a plurality of protrusions and a plurality of grooves arranged at intervals, and the protrusions and the grooves are all pyramidal in shape.

7. The display panel according to any one of claims 1 to 5, characterized in that, The display panel further includes an insulating layer (40) and a transparent conductive layer (50). The insulating layer (40) is located on the driving substrate (20) and covers the light-emitting unit (100). The insulating layer (40) has through holes that expose each of the light-emitting units (100). The transparent conductive layer (50) is located on the surface of the insulating layer (40) and is connected to each of the light-emitting units (100) through the via.

8. The display panel according to claim 7, characterized in that, The display panel further includes a connecting electrode (60) located on the surface of the transparent conductive layer (50) and in the gap between each of the light-emitting units (100).

9. The display panel according to any one of claims 1 to 5, characterized in that, The display panel also includes a plurality of bonding metal blocks (72) corresponding one-to-one with the light-emitting unit (100). The bonding metal blocks (72) are located on the driving substrate (20), and each light-emitting unit (100) is located on the corresponding bonding metal block (72). The orthographic projection of the light-emitting unit (100) on the surface of the driving substrate (20) lies within the orthographic projection of the corresponding bonding metal block (72) on the surface of the driving substrate (20).

10. A method for manufacturing a display panel, characterized in that, The preparation method includes: A light-emitting functional layer (10) is formed on the substrate (70); The light-emitting functional layer (10) is bonded to the driving substrate (20), and the substrate (70) is removed, so that the light-emitting functional layer (10) is electrically connected to the driving substrate (20); The light-emitting functional layer (10) is graphically processed to form multiple light-emitting units (100) arranged at intervals; A light-collecting structure (30) is formed on the side of the light-emitting functional layer (10) away from the driving substrate (20). The light-collecting structure (30) corresponds one-to-one with the light-emitting unit (100). The orthographic projection of the light-emitting unit (100) on the surface of the driving substrate (20) is located within the orthographic projection of the corresponding light-collecting structure on the surface of the driving substrate (20). The surface of the end of the light-collecting structure (30) away from the driving substrate (20) is an arc surface, and the arc surface is a roughened surface (31).

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