Display panel and display apparatus

Abstract

Provided in the present application are a display panel and a display apparatus. The display panel comprises a first sub-pixel and a second sub-pixel, wherein the first sub-pixel comprises a first light-emitting unit, the second sub-pixel comprises a second light-emitting unit and a third light-emitting unit that are stacked, the emission color of the second light-emitting unit is the same as the emission color of the third light-emitting unit, and the emission color of the second light-emitting unit is different from the emission color of the first light-emitting unit, thereby reducing the problem of crosstalk in stacked light-emitting devices.

Description

Display panel and display device Technical Field

[0001] This invention relates to the field of display technology, and more particularly to a display panel and display device. Background Technology

[0002] With the development of flat panel display technology, customers' requirements for display stability are gradually increasing. In recent years, Organic Light Emitting Diode (OLED) displays have developed rapidly worldwide, and OLED display technology has become increasingly sophisticated. Under this environment, the demand for stacked OLED devices has increased, and major display manufacturers have invested resources in technology and product development, launching stacked devices with various structures.

[0003] Currently, multiple light-emitting layers in stacked OLED devices need to be connected using a common layer with strong conductivity. This common layer includes materials with high lateral conductivity, which leads to severe pixel color crosstalk in stacked OLED devices, affecting the display effect. Invention Overview

[0004] This invention provides a display panel and display device to alleviate the shortcomings of related technologies.

[0005] To achieve the above functions, the technical solutions provided in this application are as follows:

[0006] In a first aspect, embodiments of this application provide a display panel, including:

[0007] The first sub-pixel includes the first light-emitting unit;

[0008] The second sub-pixel includes a second light-emitting unit and a third light-emitting unit stacked together. The light-emitting color of the second light-emitting unit is the same as the light-emitting color of the third light-emitting unit, and the light-emitting color of the second light-emitting unit is different from the light-emitting color of the first light-emitting unit.

[0009] The luminous efficiency of the second light-emitting unit and / or the third light-emitting unit is less than that of the first light-emitting unit.

[0010] Secondly, embodiments of this application provide a display device, the display device including a display panel, the display panel comprising:

[0011] The first sub-pixel includes the first light-emitting unit;

[0012] The second sub-pixel includes a second light-emitting unit and a third light-emitting unit stacked together. The light-emitting color of the second light-emitting unit is the same as the light-emitting color of the third light-emitting unit, and the light-emitting color of the second light-emitting unit is different from the light-emitting color of the first light-emitting unit.

[0013] The luminous efficiency of the second light-emitting unit and / or the third light-emitting unit is less than that of the first light-emitting unit. Attached Figure Description

[0014] The technical solution and other beneficial effects of the present invention will become apparent from the following detailed description of specific embodiments of the invention, in conjunction with the accompanying drawings.

[0015] Figure 1 is a schematic diagram of the structure of the display panel provided in an embodiment of this application;

[0016] Figure 2 is a cross-sectional schematic diagram of the corresponding AA' position in Figure 1 provided in an embodiment of this application;

[0017] Figure 3 is a schematic diagram of the structure of the display panel provided in Embodiment 1 of this application;

[0018] Figure 4 is a schematic diagram of the display panel provided in Comparative Example 1;

[0019] Figure 5 is a schematic diagram of the display panel provided in Comparative Example 2;

[0020] Figure 6 is a schematic diagram of the display panel provided in Comparative Example 3;

[0021] Figure 7 is a schematic diagram of the structure of the display device provided in the embodiment of this application. Implementation methods of this application

[0022] 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 some embodiments of this application, and not all 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. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working mode of the device, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only, and features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections or connections that allow communication; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] The following disclosure provides many different embodiments for implementing different structures of this application. To simplify the disclosure of this application, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0026] This application provides a display panel and a display device. These will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0027] Please refer to Figures 1 and 2; wherein, Figure 1 is a structural schematic diagram of the display panel provided in the embodiment of this application; and Figure 2 is a cross-sectional schematic diagram of the corresponding AA' position in Figure 1 provided in the embodiment of this application.

[0028] This embodiment provides a display panel 1, which includes, but is not limited to, an organic light-emitting diode (OLED) display panel 1. The display panel 1 includes a first sub-pixel 110 and a second sub-pixel 120. The first sub-pixel 110 includes a first light-emitting unit 12241. The second sub-pixel 120 includes a second light-emitting unit 12242 and a third light-emitting unit 12331 stacked together. The emission color of the second light-emitting unit 12242 is the same as the emission color of the third light-emitting unit 12331, and the emission color of the second light-emitting unit 12242 is different from the emission color of the first light-emitting unit 12241. The luminous efficiency of the second light-emitting unit 12242 and / or the third light-emitting unit 12331 is less than the luminous efficiency of the first light-emitting unit 12241.

[0029] Specifically, the display panel 1 includes a substrate 11 and a light-emitting device layer 12. The light-emitting device layer 12 is located on one side of the substrate 11 and includes an anode layer 121, a first light-emitting stack 122, a second light-emitting stack 123, and a cathode layer 124.

[0030] The anode layer 121 is disposed on the substrate 11. The anode layer 121 can serve as the bottom electrode of the light-emitting device layer 12 for injecting forward charge carriers (holes). The anode layer 121 can be made of a material with high conductivity and high light transmittance, such as indium tin oxide (ITO), indium zinc oxide (IZO), or other transparent conductive oxides.

[0031] The first light-emitting stack 122 includes a first light-emitting unit 12241 and a second light-emitting unit 12242. The light-emitting color of the first light-emitting unit 12241 is different from the light-emitting color of the second light-emitting unit 12242. The light-emitting efficiency of the second light-emitting unit 12242 is less than that of the first light-emitting unit 12241. The light-emitting color of the first light-emitting unit 12241 can be red or green, and the light-emitting color of the second light-emitting unit 12242 can be blue.

[0032] The second light-emitting stack 123 includes the third light-emitting unit 12331. The light emission color of the third light-emitting unit 12331 is different from the light emission color of the first light-emitting unit 12241. The luminous efficiency of the third light-emitting unit 12331 is less than that of the first light-emitting unit 12241. The orthographic projection of the second light-emitting stack 123 on the substrate covers the orthographic projection of the second light-emitting unit 12242 on the substrate. The third light-emitting unit 12331 and the second light-emitting unit 12242 are overlapped, thereby improving the luminous efficiency of the second sub-pixel 120. At the same time, by setting the luminous efficiency of the second light-emitting unit 12242 and the third light-emitting unit 12331 to be less than that of the first light-emitting unit 12241, the problem of excessive power consumption caused by the increase in brightness of the second sub-pixel 120 is avoided, thereby improving the overall brightness performance of the display panel 1.

[0033] The cathode layer 124 is disposed on the side of the light-emitting device layer 12 away from the anode layer 121. The cathode layer 124 can serve as the top electrode of the light-emitting device layer 12 for injecting negative charge carriers (electrons). The cathode layer 124 may also include a transparent conductive layer, such as indium tin oxide (ITO) or indium zinc oxide (IZO), to achieve higher transmittance and improve light extraction efficiency.

[0034] It should be noted that in traditional multilayer light-emitting devices, different sub-pixels typically contain an equal number of light-emitting units stacked together. The lateral conductivity of multiple light-emitting units can easily lead to charge diffusion, interfering with the normal light emission of other sub-pixels. It is understood that in this embodiment, the first sub-pixel 110 includes one light-emitting unit (first light-emitting unit 12241), and the second sub-pixel 120 includes two light-emitting units (second light-emitting unit 12242 and third light-emitting unit 12331). By adjusting the number and arrangement of the light-emitting units, the charge diffusion problem caused by redundant light-emitting units is avoided, the crosstalk problem between light-emitting units of different colors is suppressed, and the display uniformity of the display panel is improved.

[0035] In one embodiment, the display panel 1 further includes a charge generation layer 125 located between the first light-emitting stack 122 and the second light-emitting stack 123. The charge generation layer 125 includes a first charge generation layer 1251 and a second charge generation layer 1252. The first charge generation layer 1251 is disposed between the second light-emitting unit 12242 and the third light-emitting unit 12331, and the second charge generation layer 1252 is disposed between the first charge generation layer 1251 and the first light-emitting unit 12241 and the second light-emitting unit 12242, thereby ensuring that charge carriers are injected only into the target light-emitting unit. The first charge generation layer 1251 and the second charge generation layer 1252 are in contact with each other, and the lateral conductivity of the second charge generation layer 1252 is less than the lateral conductivity of the first charge generation layer 1251, thereby further suppressing charge diffusion between sub-pixels and reducing color crosstalk.

[0036] Specifically, the first charge generation layer 1251 can be a P-type charge generation layer, and the second charge generation layer 1252 can be an n-type charge generation layer. The first charge generation layer 1251, the second light-emitting unit 12242, and the third light-emitting unit 12331 are overlapped. The second charge generation layer 1252, the first light-emitting unit 12241, and the second light-emitting unit 12242 are overlapped. That is, the orthographic projection of the first charge generation layer 1251 on the substrate 11 covers the orthographic projection of the second light-emitting unit 12242 on the substrate 11, and the orthographic projection of the first charge generation layer 1251 on the substrate 11 covers the orthographic projection of the third light-emitting unit 12331 on the substrate 11. The orthographic projection of the second charge generation layer 1252 on the substrate 11 covers the orthographic projection of the first light-emitting stack 122 on the substrate 11. Thus, by setting the first charge generation layer 1251 and the second charge generation layer 1252 and clarifying their positions in the stacked structure, the injection path of charge carriers can be guided and diverted.

[0037] It is understood that the first charge generation layer 1251 is located between the second light-emitting unit 12242 and the third light-emitting unit 12331, thereby providing an injection path for charge carriers for the second light-emitting unit 12242 and the third light-emitting unit 12331, and ensuring that the injected charge can be effectively recombinated without diffusing to other regions; the second charge generation layer 1252 is located between the first charge generation layer 1251 and the first light-emitting stack 122, thereby ensuring that charge carriers are injected only into the target light-emitting unit.

[0038] It should be noted that in related technologies, multiple light-emitting layers of a stacked light-emitting device are usually connected by a charge generation layer 125 with high conductivity to ensure the balance of carrier injection and the overall luminous efficiency of the device. However, due to the high lateral conductivity of the charge generation layer 125, color crosstalk may occur between adjacent sub-pixels in the stacked light-emitting device, thereby affecting the display effect. For example, a sub-pixel that should emit red light may be mistakenly injected with green or blue charge, resulting in color mixing and thus reducing the purity and quality of the displayed image.

[0039] It is understood that in this embodiment, by placing the first charge generation layer 1251 between the second light-emitting unit 12242 and the third light-emitting unit 12331, and placing the second charge generation layer 1252 between the first charge generation layer 1251 and the first light-emitting stack 122, the second charge generation layer 1252 covers the first light-emitting unit 12241 and the second light-emitting unit 12242, thereby effectively controlling the charge injection path, ensuring that charge carriers are injected only into the target light-emitting unit, avoiding lateral charge diffusion between the first sub-pixel 110 and the second sub-pixel 120, thereby reducing the crosstalk effect of adjacent color sub-pixels and improving the display effect of the display panel 1.

[0040] Meanwhile, by setting the lateral conductivity of the second charge generation layer 1252 to be less than that of the first charge generation layer 1251, charge diffusion between the first sub-pixel 110 and the second sub-pixel 120 can be effectively suppressed, preventing color crosstalk. It can also ensure efficient charge transfer between the second light-emitting unit 12242 and the third light-emitting unit 12331, thereby improving the overall luminous efficiency of the stacked light-emitting unit.

[0041] In one embodiment, the display panel 1 includes a third sub-pixel 130, the third sub-pixel 130 including the fourth light-emitting unit 12243, the light-emitting colors of the first light-emitting unit 12241, the second light-emitting unit 12242 and the fourth light-emitting unit 12243 are all different, and the fourth light-emitting unit 12243 is disposed between the base plate and the second charge generating layer 1252.

[0042] Specifically, the first light-emitting stack 122 includes a first light-emitting unit 12241, a second light-emitting unit 12242, and a fourth light-emitting unit 12243; wherein the light-emitting color of the first light-emitting unit 12241 can be red, the light-emitting color of the fourth light-emitting unit 12243 can be green, and the light-emitting colors of the second light-emitting unit 12242 and the third light-emitting unit 12243 can be blue, thereby ensuring that the display panel 1 can achieve full color gamut coverage and meet the requirements of high-quality display.

[0043] It is understood that this embodiment, by setting the first charge generation layer 1251, the second light-emitting unit 12242, and the third light-emitting unit 12331 to overlap, the first charge generation layer 1251, the first light-emitting unit 12241, and the fourth light-emitting unit 12243 to not overlap, the second charge generation layer 1252 and the first light-emitting stack 122 to overlap, and the second charge generation layer 1252 and the first light-emitting unit 12241, the second light-emitting unit 12242, and the fourth light-emitting unit 12243 to overlap, can provide an efficient charge transport path between the second light-emitting unit 12242 and the third light-emitting unit 12331, ensuring balanced carrier injection in each light-emitting unit and improving overall luminous efficiency; at the same time, it avoids charge diffusion in the first sub-pixel 110 and the third sub-pixel 130, reducing crosstalk caused by lateral carrier diffusion.

[0044] In one embodiment, the first light-emitting stack 122 includes a hole injection layer 1221, a hole transport layer 1222, a first electron blocking layer 1223, a first light-emitting layer 1224, a first hole blocking layer 1225, and a first electron transport layer 1226. The hole injection layer 1221 is disposed between the anode layer 121 and the first light-emitting layer 1224 to optimize hole injection efficiency; the hole transport layer 1222 is disposed between the hole injection layer 1221 and the first light-emitting layer 1224 to improve hole transport capability; and the first electron blocking layer 1223 is disposed between the hole transport layer 1222 and the first light-emitting layer. Between 1224, a first light-emitting layer 1224 is used to block the reverse migration of electrons towards holes, thereby enhancing luminous efficiency; the first light-emitting layer 1224 includes the first light-emitting unit 12241, the second light-emitting unit 12242, and the fourth light-emitting unit 12243; the first hole-blocking layer 1225 is disposed between the first light-emitting layer 1224 and the second charge-generating layer 1252 to prevent the diffusion of holes into the electron transport region, further improving the energy utilization of the device; the first electron transport layer 1226 is disposed between the first hole-blocking layer 1225 and the second charge-generating layer 1252 to improve electron transport efficiency.

[0045] The hole injection layer 1221, the hole transport layer 1222, the first electron blocking layer 1223, the first light-emitting layer 1224, the first hole blocking layer 1225, the first electron transport layer 1226, and the second charge generation layer 1252 are in contact with each other, realizing efficient transport and injection of charge carriers, ensuring the transmission stability of the display panel 1 during operation, thereby improving the light-emitting performance and display effect of the display panel 1.

[0046] The first electron blocking layer 1223 includes a first electron blocking unit 12231, a second electron blocking unit 12232, and a third electron blocking unit 12233. The orthographic projection of the first light-emitting unit 12241 on the substrate 11 overlaps with the orthographic projection of the first electron blocking unit 12231 on the substrate 11. The orthographic projection of the second light-emitting unit 12242 on the substrate 11 overlaps with the orthographic projection of the second electron blocking unit 12232 on the substrate 11. The orthographic projection of the fourth light-emitting unit 12243 on the substrate 11 overlaps with the orthographic projection of the third electron blocking unit 12233 on the substrate 11.

[0047] The first hole blocking layer 1225, the first electron transport layer 1226, and the second charge generating layer 1252 can be manufactured using a common metal mask (CMM) vapor deposition method. It is understood that the common metal mask process achieves aligned vapor deposition of each functional layer (the first hole blocking layer 1225, the first electron transport layer 1226, and the second charge generating layer 1252) using a unified mask, effectively avoiding misalignment between layers, improving the fitting accuracy between functional layers, and ensuring the consistency of the first light-emitting stack 122 structure. Simultaneously, it significantly reduces the types and number of masks used, simplifies the production process, and further reduces manufacturing costs.

[0048] Specifically, the second charge generation layer 1252 includes a first charge generation sub-unit 12521 and a second charge generation sub-unit 12522. The first charge generation sub-unit 12521 covers the first light-emitting unit 12241, and the second charge generation sub-unit 12522 covers the second light-emitting unit 12242. Both the first charge generation sub-unit 12521 and the second charge generation sub-unit 12522 include ytterbium, and the ytterbium content in the first charge generation sub-unit 12521 is equal to the ytterbium content in the second charge generation sub-unit 12522. Alternatively, both the first charge generation sub-unit 12521 and the second charge generation sub-unit 12522 include lithium, and the lithium content in the first charge generation sub-unit 12521 is equal to the lithium content in the second charge generation sub-unit 12522. This ensures the consistency of elemental content in each part of the second charge generation layer 1252 and enhances the overall charge transport performance of the second charge generation layer 1252.

[0049] It is understood that the second charge generation layer 1252 includes a first charge generation subunit 12521 and a second charge generation subunit 12522. By using a common metal mask evaporation process to manufacture the second charge generation layer 1252, high-precision material deposition can be achieved, thereby ensuring the consistency of the material composition between the first charge generation subunit 12521 and the second charge generation subunit 12522. Specifically, through the common metal mask evaporation process, materials containing ytterbium or lithium can be uniformly deposited onto the first electron transport layer. On 1226, a second charge-generating layer 1252 with uniform thickness and highly uniform material composition is formed, such that the ytterbium content in the first charge-generating subunit 12521 is equal to the ytterbium content in the second charge-generating subunit 12522; or, both the first charge-generating subunit 12521 and the second charge-generating subunit 12522 include lithium, and the lithium content in the first charge-generating subunit 12521 is equal to the lithium content in the second charge-generating subunit 12522, thereby improving the performance stability of the charge-generating layer 125.

[0050] In one embodiment, the second light-emitting stack 123 includes a second hole transport layer 1231, a second electron blocking layer 1232, a second light-emitting layer 1233, a second hole blocking layer 1234, a second electron transport layer 1235, and an electron injection layer 1236; the second hole transport layer 1231 is disposed between the first charge generation layer 1251 and the second light-emitting layer 1233, for efficiently transporting holes and optimizing their injection efficiency; the second electron blocking layer 1232 is disposed between the second hole transport layer 1231 and the second light-emitting layer 1233, for blocking the reverse migration of electrons and improving electron-hole recombination efficiency; The second light-emitting layer 1233 includes the third light-emitting unit 12331; the second hole-blocking layer 1234 is disposed on the side of the third light-emitting unit 12331 away from the second electron-blocking layer 1232, which can suppress the diffusion of holes to the electron transport region, thereby improving the light-emitting performance; the second electron transport layer 1235 is disposed on the side of the second hole-blocking layer 1234 away from the third light-emitting unit 12331, which is used for efficient electron transport; the electron injection layer 1236 is disposed between the second electron transport layer 1235 and the cathode layer 124, which is used to improve the electron injection efficiency and ensure that electrons can be quickly transferred to the light-emitting region.

[0051] The first charge generation layer 1251, the second hole transport layer 1231, the second electron blocking layer 1232, the third light-emitting unit 12331, the second hole blocking layer 1234, the second electron transport layer 1235, and the electron injection layer 1236 are in contact with each other, thereby ensuring the continuity of charge transport channels between the functional layers, realizing efficient injection, transport, and recombination of holes and electrons, and further improving the luminous efficiency and display performance of the display panel 1.

[0052] It should be noted that the orthographic projection of the electron injection layer 1236 on the substrate 11 covers the second light-emitting stack 123, and the orthographic projection of the electron injection layer 1236 on the substrate 11 covers the first light-emitting stack 122. Furthermore, the electron injection layer 1236 is in direct contact with the second charge generation layer 1252 and the second electron transport layer 1235, thereby ensuring that electrons can be efficiently transported from the electron injection layer 1236 to each light-emitting stack, realizing efficient recombination of charge carriers, and thus improving the overall luminous efficiency of the light-emitting device. At the same time, the thickness of the second light-emitting stack 123 is greater than or equal to 1000 angstroms and less than or equal to 1500 angstroms, which can effectively ensure the optical performance of the second light-emitting stack 123 and avoid the problem of reduced flatness of the light-emitting device layer 12 due to its excessive thickness.

[0053] In one embodiment, the first light-emitting unit 12241 emits light of a first wavelength, the second light-emitting unit 12242 and the third light-emitting unit 12331 both emit light of a second wavelength, and the third light-emitting unit 12331 emits light of a third wavelength.

[0054] The first light-emitting unit 12241 can be a red light-emitting unit, which can emit light with a first wavelength of 620 nm to 750 nm; the second light-emitting unit 12242 and the third light-emitting unit 12331 can be blue light-emitting units, which can emit light with a second wavelength of 380 nm to 495 nm; the fourth light-emitting unit 12243 can be a green light-emitting unit, which can emit light with a third wavelength of 495 nm to 570 nm, thereby realizing the light-emitting characteristics of the RGB three primary colors in the display panel 1, and providing the display panel 1 with high-quality color performance and spectral coverage.

[0055] Furthermore, the distance L1 between the center of the first light-emitting unit 12241 and the anode layer 121 is L1 = (2a - 1)λ1 / 4; the distance L2 between the center of the second light-emitting unit 12242 and the anode layer 121 is L2 = (2b - 1)λ2 / 4; the distance L3 between the center of the third light-emitting unit 12331 and the anode layer 121 is L3 = (2c - 1)λ2 / 4; the distance L4 between the center of the fourth light-emitting unit 12243 and the anode layer 121 is L4 = (2d - 1)λ1 / 4; where λ1 is the first wavelength, λ2 is the second wavelength, λ3 is the third wavelength, and a, b, c, d are all microcavity resonance nodes, a, b, c, d are all positive integers, and a = b = d < c. Thus, by setting the distance between the center of each light-emitting unit and the anode layer 121 to a specific microcavity resonance node, the microcavity resonance enhancement effect of lights with different wavelengths is achieved, thereby improving the light-emitting efficiency of the display panel 1.

[0056] Specifically, in this embodiment, by setting the distance between the center of each light-emitting unit and the anode layer 121 to a specific microcavity resonance node, the light-emitting frequency of each light-emitting unit can be matched with the microcavity resonance. That is, according to the microcavity resonance principle, when the distance between the center of the light-emitting unit and the anode layer 121 conforms to a certain node of the resonance wavelength, the radiation of light will be more efficient, generating a stronger electric field and optical field coupling, thereby improving the light-emitting efficiency.

[0057] It can be understood that since the first light-emitting unit 12241, the second light-emitting unit 12242, and the third light-emitting unit 12331 emit lights with different wavelengths (the first wavelength, the second wavelength, and the third wavelength) respectively, the lights of these wavelengths can be enhanced differently through the resonance structure. By precisely matching the microcavity resonance nodes (a = b = d), the microcavity path lengths of the first light-emitting unit 12241, the second light-emitting unit 12242, and the fourth light-emitting unit 12243 are similar, adapting to the characteristics of their light wave wavelengths, ensuring brightness balance, and reducing the brightness attenuation difference of lights of different colors with the change of viewing angle, thereby optimizing the viewing angle consistency of the display panel 1.

[0058] At the same time, in the design of the display panel 1, blue light usually has higher energy and brightness. If not controlled, its excessive brightness may cause an imbalance in the RGB spectrum, thereby affecting the accuracy and consistency of the display color. In this embodiment, by setting a = b = d < c, the microcavity path of the third light-emitting unit 1233 is longer, providing more nodes to weaken the excessive brightness of blue light, thereby balancing the RGB spectrum performance.

[0059] In one embodiment, the display panel 1 further includes a cover layer 13, which is disposed on the side of the cathode layer 124 away from the light-emitting device layer 12. The cover layer 13 is in contact with the anode layer 121. The cover layer 13 includes a first cover portion 131, a second cover portion 132, and a third cover portion 133. The first cover portion 131 is disposed on the light-emitting side of the first light-emitting unit 12241 and overlaps with the first light-emitting unit 12241. The second cover portion 132 is disposed on the light-emitting side of the second light-emitting unit 12242 and the third light-emitting unit 12331 and overlaps with the second light-emitting unit 12242 and the third light-emitting unit 12331. The third cover portion 133 is disposed on the light-emitting side of the fourth light-emitting unit 12243 and overlaps with the fourth light-emitting unit 12243.

[0060] The thickness of the first covering portion 131 is equal to the thickness of the third covering portion 133, and the thickness of the first covering portion 131 is less than the thickness of the second covering portion 132; the thickness of the first covering portion 131 is greater than or equal to 800 angstroms and less than or equal to 1000 angstroms; the thickness of the second covering portion 132 is greater than or equal to 800 angstroms and less than or equal to 1200 angstroms; the refractive index of the first covering portion 131 is equal to the refractive index of the third covering portion 133, and the refractive index of the first covering portion 131 is greater than the refractive index of the second covering portion 132; the first covering portion 131... The refractive index of the first cover 131 is greater than or equal to 1.6 and less than or equal to 1.8; the refractive index of the second cover 132 is greater than or equal to 1.6 and less than or equal to 1.7; the refractive index of the third cover 13 is greater than or equal to 1.6 and less than or equal to 1.8. By precisely designing the thickness and refractive index parameters of the cover (first cover 131, second cover 132 and third cover 133), the optical performance of the light-emitting device layer 12 is optimized, avoiding the problem of inconsistent brightness and color due to differences in microcavity design, which leads to the deterioration of the viewing angle distortion problem.

[0061] Specifically, when the first sub-pixel 110, the second sub-pixel 120, and the third sub-pixel 130 use microcavity lengths with different numbers of microcavity resonant nodes, their brightness decays inconsistently with viewing angle deflection, leading to a deterioration in the visual effect of character bias. In this embodiment, the second light-emitting layer 123 includes the second light-emitting unit 12242 and the third light-emitting unit 12331, which has high brightness. In practical applications, this may lead to differences in brightness decay and viewing angle deviation.

[0062] This embodiment ensures the consistency of the optical paths of the first sub-pixel 110 and the third sub-pixel 130 by setting the thickness and / or refractive index of the first covering portion 131 to be equal to the thickness and / or refractive index of the third covering portion 133. This makes the light propagation characteristics consistent in the first sub-pixel 110 and the third sub-pixel 130. At the same time, by setting the thickness of the first covering portion 131 to be less than the thickness of the second covering portion 132, and / or setting the refractive index of the first covering portion 131 to be greater than the refractive index of the second covering portion 132, it helps to adjust the brightness difference between the first sub-pixel 110 and the second sub-pixel 120, making the brightness change of the entire display panel 1 more balanced under different viewing angles, thereby improving the stability and uniformity of the display.

[0063] The technical solutions of the embodiments of this application will now be described in conjunction with specific examples.

[0064] Please refer to Figures 3, 4, 5, and 6; wherein, Figure 3 is a schematic diagram of the structure of the display panel provided in Embodiment 1 of this application; Figure 4 is a schematic diagram of the structure of the display panel provided in Comparative Example 1; Figure 5 is a schematic diagram of the structure of the display panel provided in Comparative Example 2; and Figure 6 is a schematic diagram of the structure of the display panel provided in Comparative Example 3.

[0065] As shown in Figure 3, in Embodiment 1, the display panel 1 includes a substrate 11, an anode layer 121, a hole injection layer 1221, a hole transport layer 1222, a first electron blocking layer 1223, a first light-emitting layer 1224, a first hole blocking layer 1225, a first electron transport layer 1226, a second charge generating layer 1252, a first charge generating layer 1251, a second hole transport layer 1231, a second electron blocking layer 1232, a second light-emitting layer 1233, a second hole blocking layer 1234, a second electron transport layer 1235, an electron injection layer 1236, and a cathode layer 124, all stacked together.

[0066] The first charge generating layer 1251, the second light-emitting unit 12242, and the third light-emitting unit 12331 are overlapped, and the second charge generating layer 1252, the first light-emitting unit 12241, and the second light-emitting unit 12242 are overlapped. The first electron blocking layer 1223 includes a first electron blocking unit 12231, a second electron blocking unit 12232, and a third electron blocking unit 12233. The orthographic projection of the first light-emitting unit 12241 on the substrate 11 overlaps with the orthographic projection of the first electron blocking unit 12231 on the substrate 11. The orthographic projection of the second light-emitting unit 12242 on the substrate 11 overlaps with the orthographic projection of the second electron blocking unit 12232 on the substrate 11. The orthographic projection of the fourth light-emitting unit 12243 on the substrate 11 overlaps with the orthographic projection of the third electron blocking unit 12233 on the substrate 11. The orthographic projection of the second light-emitting unit 12242 on the substrate 11 overlaps with the orthographic projection of the second electron blocking layer 1232 on the substrate 11.

[0067] The first light-emitting layer 1224 includes a first light-emitting unit 12241, a second light-emitting unit 12242, and a fourth light-emitting unit 12243. The microcavity resonant nodes of the first light-emitting unit 12241, the second light-emitting unit 12242, and the fourth light-emitting unit 12243 are all 2. The second light-emitting layer 1233 includes a third light-emitting unit 12331. The third light-emitting unit 12331 and the second light-emitting unit 12242 are overlapped. The microcavity resonant node of the third light-emitting unit 12331 is 3. The first hole blocking layer 1225, the first electron transport layer 1226, and the second charge generating layer 1252 are all manufactured by common metal mask (CMM) evaporation.

[0068] As shown in Figure 4, in Comparative Example 1, the display panel 2 includes a substrate 21, an anode layer 22, a hole injection layer 23, a hole transport layer 24, an electron blocking layer 25, a light-emitting layer 26, a hole blocking layer 27, an electron transport layer 28, an electron injection layer 29, and a cathode layer 230, which are stacked together.

[0069] The light-emitting layer 26 includes a red light-emitting unit 261, a green light-emitting unit 262, and a blue light-emitting unit 263. The electron blocking layer 25 includes a first electron blocking unit 251, a second electron blocking unit 252, and a third electron blocking unit 253. The orthographic projection of the red light-emitting unit 261 on the substrate 11 overlaps with the orthographic projection of the first electron blocking unit 251 on the substrate 11. The orthographic projection of the green light-emitting unit 262 on the substrate 11 overlaps with the orthographic projection of the second electron blocking unit 252 on the substrate 11. The orthographic projection of the blue light-emitting unit 263 on the substrate 11 overlaps with the orthographic projection of the third electron blocking unit 253 on the substrate 11.

[0070] The microcavity resonant nodes of the red light emitting unit 261, the green light emitting unit 262, and the blue light emitting unit 263 are all 2.

[0071] By comparing Example 1 and Comparative Example 1, it can be seen that the stacked structure design in Example 1 (the second light-emitting unit 12242 and the third light-emitting unit 12331 are stacked) effectively extends the propagation path of light in the microcavity. The stacking of multiple light-emitting units can increase the multiple interactions between light and the functional layer, making the reflection, refraction and interference of light more sufficient, and effectively improving the luminous efficiency. In contrast, for Comparative Example 1, which has a single-layer light-emitting structure (red light-emitting unit 261, green light-emitting unit 262 and blue light-emitting unit 263 are set in the same layer), the light path is relatively short, the coupling strength between light and the microcavity structure is weak, and the microcavity resonance effect cannot be fully excited, resulting in relatively low luminous efficiency.

[0072] As shown in Figure 5, in Embodiment 2, the display panel 3 includes a substrate 31, an anode layer 32, a hole injection layer 33, a hole transport layer 34, a first electron blocking layer 35, a first light-emitting layer 36, a first hole blocking layer 37, a first electron transport layer 38, an n-type charge generating layer 39, a p-type charge generating layer 310, a second hole transport layer 311, a second electron blocking layer 312, a second light-emitting layer 3313, a second hole blocking layer 314, a second electron transport layer 315, an electron injection layer 316, and a cathode layer 317, all stacked together.

[0073] The first light-emitting layer 36 includes a first red light-emitting unit 361, a first green light-emitting unit 362, and a first blue light-emitting unit 363, wherein the microcavity resonant nodes of the first red light-emitting unit 361, the first green light-emitting unit 362, and the first blue light-emitting unit 363 are all 2; the second light-emitting layer 313 includes a second red light-emitting unit 3131, a second green light-emitting unit 3132, and a second blue light-emitting unit 3133, wherein the microcavity resonant nodes of the second red light-emitting unit 3131, the second green light-emitting unit 3132, and the second blue light-emitting unit 3133 are all 2.

[0074] The first electron blocking layer 35 includes a first electron blocking unit 351, a second electron blocking unit 352, and a third electron blocking unit 353. The orthographic projection of the first red light emitting unit 361 on the substrate 11 overlaps with the orthographic projection of the first electron blocking unit 351 on the substrate 11. The orthographic projection of the first green light emitting unit 362 on the substrate 11 overlaps with the orthographic projection of the second electron blocking unit 352 on the substrate 11. The orthographic projection of the first blue light emitting unit 363 on the substrate 11 overlaps with the orthographic projection of the third electron blocking unit 353 on the substrate 11.

[0075] The second electron blocking layer 312 includes a fourth electron blocking unit 3121, a fifth electron blocking unit 3122, and a sixth electron blocking unit 3123. The orthographic projection of the second red light emitting unit 3131 on the substrate 11 overlaps with the orthographic projection of the fourth electron blocking unit 3121 on the substrate 11. The orthographic projection of the second green light emitting unit 3132 on the substrate 11 overlaps with the orthographic projection of the fifth electron blocking unit 3122 on the substrate 11. The orthographic projection of the second blue light emitting unit 3133 on the substrate 11 overlaps with the orthographic projection of the sixth electron blocking unit 3123 on the substrate 11.

[0076] In this configuration, the first red light emitting unit 361 and the second red light emitting unit 3131 are overlapped, the first green light emitting unit 362 and the second green light emitting unit 31432 are overlapped, the first blue light emitting unit 363 and the second blue light emitting unit 3133 are overlapped, and the first light-emitting layer 36, the n-type charge generating layer 39, the p-type charge generating layer 310 and the second light-emitting layer 313 are all overlapped. Thus, the high conductivity of the n-type charge generating layer 39 and the p-type charge generating layer 310 enables charge transfer between the upper and lower light-emitting layers. However, in actual use, this can easily cause color crosstalk between pixels.

[0077] By comparing Embodiment 1 and Comparative Example 2, it can be seen that in Comparative Example 2, a charge generation layer (n-type charge generation layer 39 and p-type charge generation layer 310) with strong conductivity is required to connect the first light-emitting layer 36 and the second light-emitting layer 313. The charge generation layer uses a material with high lateral conductivity, which leads to a relatively serious color crosstalk phenomenon between pixels in the display panel 3, thus affecting the image quality. In contrast, Embodiment 1 sets the first light-emitting layer 1224 to include a first light-emitting unit 12241, a second light-emitting unit 12242 and a fourth light-emitting unit 12243, and the second light-emitting layer 1233 to include a third light-emitting unit 12331. The third light-emitting unit 12331 and the second light-emitting unit 12242 are overlapped, thereby effectively adjusting the number and arrangement of the light-emitting units and avoiding the crosstalk problem caused by the high lateral conductivity of the charge generation layer 125 in the stacked light-emitting device in Comparative Example 2, thereby improving the image quality of the display panel 1.

[0078] As shown in Figure 6, in Comparative Example 3, the display panel 4 includes a substrate 41, an anode layer 42, a hole injection layer 43, a hole transport layer 44, a first electron blocking layer 45, a first light-emitting layer 46, a first hole blocking layer 47, a first electron transport layer 48, an n-type charge generating layer 49, a p-type charge generating layer 410, a second hole transport layer 411, a second electron blocking layer 412, a second light-emitting layer 413, a second hole blocking layer 414, a second electron transport layer 415, an electron injection layer 416, and a cathode layer 417, all stacked together.

[0079] The first light-emitting layer 46 includes a first red light-emitting unit 461, a first green light-emitting unit 462, and a first blue light-emitting unit 463; the second light-emitting layer 413 includes a second blue light-emitting unit 4131; wherein the first blue light-emitting unit 463, the first hole-blocking layer 47, the first electron transport layer 48, the n-type charge generation layer 49, the p-type charge generation layer 410, the second hole transport layer 411, the second electron-blocking layer 412, and the second blue light-emitting unit 4131 are stacked.

[0080] The first electron blocking layer 45 includes a first electron blocking unit 451, a second electron blocking unit 452, and a third electron blocking unit 453. The orthographic projection of the first red light emitting unit 461 on the substrate 11 overlaps with the orthographic projection of the first electron blocking unit 451 on the substrate 11. The orthographic projection of the first green light emitting unit 462 on the substrate 11 overlaps with the orthographic projection of the second electron blocking unit 452 on the substrate 11. The orthographic projection of the first blue light emitting unit 463 on the substrate 11 overlaps with the orthographic projection of the third electron blocking unit 453 on the substrate 11. The orthographic projection of the second blue light emitting unit 4131 on the substrate 11 overlaps with the orthographic projection of the second electron blocking layer 412 on the substrate 11.

[0081] The microcavity resonant nodes of the first red light emitting unit 461, the first green light emitting unit 462, and the first blue light emitting unit 463 are all 2; the microcavity resonant node of the second blue light emitting unit 4131 is 3; the first hole blocking layer 47, the first electron transport layer 48, the n-type charge generation layer 49, and the p-type charge generation layer 410 are all manufactured by fine metal mask (FMM) evaporation.

[0082] By comparing Example 1 and Comparative Example 3, it can be seen that in Example 1, the first hole blocking layer 1225, the first electron transport layer 1226, and the second charge generation layer 1252 are all manufactured using a common metal mask evaporation method. In Comparative Example 3, the first hole blocking layer 47, the first electron transport layer 48, the n-type charge generation layer 49, and the p-type charge generation layer 410 are all manufactured using a fine metal mask evaporation method. Compared with the fine metal mask evaporation method, the common metal mask evaporation method has higher efficiency and yield, does not require frequent mask replacement or complex alignment processes, is suitable for mass production, and reduces the manufacturing cost of the display panel.

[0083] Please refer to Figure 7, which is a schematic diagram of the structure of the display device provided in the embodiment of this application.

[0084] This embodiment also provides a display device 5, which includes the display panel 1 described in any of the above embodiments; it is understood that the display panel 1 has been described in detail in the above embodiments, and will not be described again here.

[0085] The display device 5 may also include a middle frame 51, which is integrated with the display panel 1 to provide support, fixation and protection for the display panel 1.

[0086] In specific applications, the display device 5 can be at least one of the following devices with display functions: smartphone, tablet computer, mobile phone, video phone, e-book reader, desktop computer, laptop computer, netbook, workstation, server, personal digital assistant, portable media player, MP3 player, mobile medical device, camera, game console, digital camera, car navigation system, electronic billboard, ATM, or wearable device.

[0087] 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.

[0088] The technical solutions provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions in the embodiments of this application.

Claims

1. A display panel, wherein, include: The first sub-pixel includes the first light-emitting unit; The second sub-pixel includes a second light-emitting unit and a third light-emitting unit stacked together. The light-emitting color of the first light-emitting unit is the same as the light-emitting color of the second light-emitting unit, and the light-emitting color of the third light-emitting unit is different from the light-emitting color of the first light-emitting unit. The luminous efficiency of the second light-emitting unit and / or the third light-emitting unit is less than that of the first light-emitting unit.

2. The display panel according to claim 1, wherein, The display panel also includes: A first charge generation layer is disposed between the second light-emitting unit and the third light-emitting unit; The second charge generation layer is disposed between the first charge generation layer and the first light-emitting unit and the second light-emitting unit; The lateral conductivity of the second charge generation layer is less than that of the first charge generation layer.

3. The display panel according to claim 2, wherein, The first charge generating layer, the second light-emitting unit, and the third light-emitting unit are overlapped; the second charge generating layer, the first light-emitting unit, and the second light-emitting unit are overlapped.

4. [Amended according to Rule 26, 10.01.2025] The display panel according to claim 2, wherein, The second charge generation layer includes a first charge generation sub-unit and a second charge generation sub-unit, wherein the first charge generation sub-unit covers the first light-emitting unit and the second charge generation sub-unit covers the second light-emitting unit; Both the first charge generating subunit and the second charge generating subunit include ytterbium, and the content of ytterbium in the first charge generating subunit is equal to the content of ytterbium in the second charge generating subunit.

5. The display panel according to claim 2, wherein, The second charge generation layer includes a first charge generation sub-unit and a second charge generation sub-unit, wherein the first charge generation sub-unit covers the first light-emitting unit and the second charge generation sub-unit covers the second light-emitting unit; Both the first charge-generating subunit and the second charge-generating subunit include lithium, and the lithium content in the first charge-generating subunit is equal to the lithium content in the second charge-generating subunit.

6. The display panel according to claim 2, wherein, The display panel further includes a third sub-pixel, which includes the fourth light-emitting unit. The light-emitting colors of the first light-emitting unit, the second light-emitting unit, and the fourth light-emitting unit are all different. The fourth light-emitting unit is disposed on the side of the second charge-generating layer away from the first charge-generating layer, and the fourth light-emitting unit overlaps with the second charge-generating layer.

7. The display panel according to any one of claims 1 to 6, wherein, The display panel also includes: A first covering portion is disposed on the light-emitting side of the first light-emitting unit, and the first covering portion overlaps with the first light-emitting unit; The second covering portion is disposed on the light-emitting side of the second light-emitting unit and the third light-emitting unit, and the second covering portion overlaps with the second light-emitting unit and the third light-emitting unit; Wherein, the thickness of the first covering part is less than the thickness of the second covering part, and / or the refractive index of the first covering part is greater than the refractive index of the second covering part.

8. The display panel according to claim 7, wherein, The thickness of the first covering portion is greater than or equal to 800 angstroms and less than or equal to 1000 angstroms; the thickness of the second covering portion is greater than or equal to 800 angstroms and less than or equal to 1200 angstroms.

9. The display panel according to claim 7, wherein, The refractive index of the first covering portion is greater than or equal to 1.6 and less than or equal to 1.8; the refractive index of the second covering portion is greater than or equal to 1.6 and less than or equal to 1.

7.

10. The display panel according to any one of claims 1 to 6, wherein, The display panel includes a substrate and a light-emitting device layer located on the substrate, the light-emitting device layer comprising: An anode layer is located on one side of the substrate; A first light-emitting stack is disposed on the side of the anode layer away from the substrate. The first light-emitting stack includes a first light-emitting unit, a second light-emitting unit, and a fourth light-emitting unit. The light-emitting colors of the first light-emitting unit, the second light-emitting unit, and the fourth light-emitting unit are all different. A charge generation layer is disposed on the side of the first light-emitting stack away from the substrate. The charge generation layer includes a first charge generation layer and a second charge generation layer. The second charge generation layer and the first light-emitting stack are overlapped. The first charge generation layer, the second light-emitting unit, and the third light-emitting unit are overlapped. The second light-emitting layer is disposed on the side of the charge-generating layer away from the first light-emitting layer. The second light-emitting layer includes the third light-emitting unit, and the third light-emitting unit and the second light-emitting unit are overlapped. The cathode layer is located on the side of the second light-emitting stack away from the charge-generating layer; The lateral conductivity of the second charge generation layer is less than that of the first charge generation layer.

11. The display panel according to claim 10, wherein, The first light-emitting stack further includes: A hole injection layer is disposed on one side of the anode layer; A hole transport layer is disposed on the side of the hole injection layer away from the anode layer; A first electron blocking layer is disposed on the side of the hole transport layer away from the hole injection layer; A first light-emitting layer is disposed on the side of the first electron blocking layer away from the hole transport layer, and the first light-emitting layer includes a first light-emitting unit, a second light-emitting unit, and a fourth light-emitting unit; A first hole-blocking layer is disposed on the side of the first light-emitting layer away from the first electron-blocking layer; and The first electron transport layer is disposed on the side of the first hole blocking layer away from the first light-emitting layer.

12. The display panel according to claim 11, wherein, The second light-emitting stack also includes: The second hole transport layer is disposed on the side of the first charge generation layer away from the second charge generation layer; The second electron blocking layer is disposed on the side of the second hole transport layer away from the first charge generation layer; The second light-emitting layer is disposed on the side of the second electron blocking layer away from the second hole transport layer, and the second light-emitting layer includes the third light-emitting unit; The second hole blocking layer is disposed on the side of the second light-emitting layer away from the second electron blocking layer; A second electron transport layer is disposed on the side of the second hole blocking layer away from the second light-emitting layer; and An electron injection layer is disposed on the side of the second electron transport layer away from the second hole blocking layer, and the electron injection layer is in direct contact with the second electron transport layer and the second charge generation layer.

13. The display panel according to claim 10, wherein, The first light-emitting unit emits light of a first wavelength, and the second and third light-emitting units both emit light of a second wavelength. The distance L1 between the center of the first light-emitting unit and the anode layer is (2a-1)λ1 / 4; The distance L2 between the center of the second light-emitting unit and the anode layer is (2b-1)λ2 / 4; The distance L3 between the center of the third light-emitting unit and the anode layer is (2c-1)λ2 / 4; Where λ1 is the first wavelength, λ2 is the second wavelength, a, b, and c are all microcavity resonant nodes, a, b, and c are all positive integers, and a = b <c。 14. A display device, wherein, Includes a display panel, the display panel comprising: The first sub-pixel includes the first light-emitting unit; The second sub-pixel includes a second light-emitting unit and a third light-emitting unit stacked together. The light-emitting color of the first light-emitting unit is the same as the light-emitting color of the second light-emitting unit, and the light-emitting color of the third light-emitting unit is different from the light-emitting color of the first light-emitting unit. The luminous efficiency of the second light-emitting unit and / or the third light-emitting unit is less than that of the first light-emitting unit.

15. The display device according to claim 14, wherein, The display panel also includes: A first charge generation layer is disposed between the second light-emitting unit and the third light-emitting unit; The second charge generation layer is disposed between the first charge generation layer and the first light-emitting unit and the second light-emitting unit; The lateral conductivity of the second charge generation layer is less than that of the first charge generation layer.

16. The display device according to claim 15, wherein, The first charge generating layer, the second light-emitting unit, and the third light-emitting unit are overlapped; the second charge generating layer, the first light-emitting unit, and the second light-emitting unit are overlapped.

17. [Amended according to Rule 26, 10.01.2025] The display device according to claim 15, wherein, The second charge generation layer includes a first charge generation sub-unit and a second charge generation sub-unit, wherein the first charge generation sub-unit covers the first light-emitting unit and the second charge generation sub-unit covers the second light-emitting unit; Both the first charge generating subunit and the second charge generating subunit include ytterbium, and the content of ytterbium in the first charge generating subunit is equal to the content of ytterbium in the second charge generating subunit.

18. The display device according to claim 15, wherein, The second charge generation layer includes a first charge generation sub-unit and a second charge generation sub-unit, wherein the first charge generation sub-unit covers the first light-emitting unit and the second charge generation sub-unit covers the second light-emitting unit; Both the first charge-generating subunit and the second charge-generating subunit include lithium, and the lithium content in the first charge-generating subunit is equal to the lithium content in the second charge-generating subunit.

19. The display device according to claim 15, wherein, The display panel further includes a third sub-pixel, which includes the fourth light-emitting unit. The light-emitting colors of the first light-emitting unit, the second light-emitting unit, and the fourth light-emitting unit are all different. The fourth light-emitting unit is disposed on the side of the second charge-generating layer away from the first charge-generating layer, and the fourth light-emitting unit overlaps with the second charge-generating layer.

20. The display device according to any one of claims 14 to 19, wherein, The display panel also includes: A first covering portion is disposed on the light-emitting side of the first light-emitting unit, and the first covering portion overlaps with the first light-emitting unit; The second covering portion is disposed on the light-emitting side of the second light-emitting unit and the third light-emitting unit, and the second covering portion overlaps with the second light-emitting unit and the third light-emitting unit; Wherein, the thickness of the first covering part is less than the thickness of the second covering part, and / or the refractive index of the first covering part is greater than the refractive index of the second covering part.

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