Display panel, preparation method thereof and display device

Abstract

The application provides a display panel, a preparation method thereof and a display device. The display panel comprises a driving substrate, a plurality of anode electrodes, a first functional layer comprising a first light-emitting stack, a second light-emitting stack and a third light-emitting stack, a first cathode electrode arranged on the first light-emitting stack and the second light-emitting stack, a charge generation layer arranged on the third light-emitting stack and the first cathode electrode, a second functional layer comprising a fourth light-emitting stack, the fourth light-emitting stack being arranged on the charge generation layer, a normal projection of the fourth light-emitting stack on the first functional layer covering the first light-emitting stack, the second light-emitting stack and the third light-emitting stack, the fourth light-emitting stack having the same color as the third light-emitting stack, and a second cathode electrode arranged on the second functional layer, a normal projection of the second cathode electrode on the first functional layer being coincident with the third light-emitting stack. The display panel reduces the cost and improves the product yield on the basis of the light-emitting device with the stack series structure.

Description

Technical Field

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

[0002] As end-user demands continue to rise, the requirements for display technology are also increasing. To meet these growing needs, various new technologies have emerged, including the recently popular Color Optimization Engine (COE), Micro Lens Array (MLA) integration technology, eLEAP technology, and tandem technology. In particular, the tandem device structure can reduce power consumption and significantly improve the lifespan of red / green / blue (R / G / B) devices, meeting the requirements of medium-sized products. However, the efficiency and lifespan of single blue devices remain relatively low, necessitating the improvement of performance through tandem structures.

[0003] However, the stacked tandem structure requires more layers of fine metal mask (FMM) evaporation, which not only increases costs but also reduces product yield. Summary of the Invention

[0004] This application provides a display panel, its manufacturing method, and a display device, aiming to solve the problems of increased cost and decreased product yield caused by the need for more layers of FMM evaporation in existing multilayer series light-emitting devices.

[0005] To address the aforementioned technical problems, the first technical solution provided in this application is: to provide a display panel. The display panel includes:

[0006] Drive substrate;

[0007] Multiple anode electrodes are arranged in an array on the driving substrate and are electrically connected to the driving substrate;

[0008] The first functional layer includes a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack, which are respectively disposed on the corresponding anode electrode;

[0009] The first cathode electrode is disposed on the first light-emitting stack and the second light-emitting stack;

[0010] The display panel also includes:

[0011] A charge generation layer is disposed on the third light-emitting stack and the first cathode electrode;

[0012] The second functional layer includes a fourth light-emitting stack, which is disposed on the charge generation layer and its orthogonal projection on the first functional layer covers the first light-emitting stack, the second light-emitting stack, and the third light-emitting stack; the fourth light-emitting stack has the same color as the third light-emitting stack.

[0013] The second cathode electrode is disposed on the second functional layer, and the orthogonal projection of the second cathode electrode on the first functional layer coincides with the third light-emitting stack.

[0014] In some embodiments, the first light-emitting stack includes a red light-emitting layer, the second light-emitting stack includes a green light-emitting layer, the third light-emitting stack includes a first blue light-emitting layer, and the fourth light-emitting stack includes a second blue light-emitting layer.

[0015] In some embodiments, the first light-emitting stack further includes a first electron blocking layer located between the anode electrode and the red light-emitting layer; the second light-emitting stack further includes a second electron blocking layer located between the anode electrode and the green light-emitting layer; the third light-emitting stack further includes a third electron blocking layer located between the anode electrode and the first blue light-emitting layer; and the fourth light-emitting stack further includes a fourth electron blocking layer located between the charge-generating layer and the second blue light-emitting layer.

[0016] The first functional layer also includes a hole injection layer and a first hole transport layer stacked between the anode electrode and the first to third light-emitting stacks, as well as a first hole blocking layer and a first electron transport layer stacked between the first to third light-emitting stacks and the first cathode electrode.

[0017] The second functional layer also includes a second hole transport layer stacked between the charge generation layer and the fourth light-emitting layer, and a second hole blocking layer and a second electron transport layer stacked between the fourth light-emitting layer and the second cathode electrode.

[0018] In some embodiments, the display panel further includes an isolation structure disposed on a driving substrate and having a plurality of pixel openings that expose a first sub-pixel, a second sub-pixel, and a third sub-pixel.

[0019] The first sub-pixel includes a first light-emitting stack and a corresponding anode electrode and a corresponding first cathode electrode, as well as a partial charge-generating layer and a partial fourth light-emitting stack located within the corresponding pixel opening;

[0020] The second sub-pixel includes a second light-emitting stack and a corresponding anode electrode and a corresponding first cathode electrode, as well as a partial charge-generating layer and a partial fourth light-emitting stack located within the corresponding pixel opening;

[0021] The third sub-pixel includes a third light-emitting stack and a corresponding anode electrode, a fourth light-emitting stack, a partial charge-generating layer located within the pixel opening, and a second cathode electrode.

[0022] To address the aforementioned technical problems, the second technical solution provided in this application is: a method for manufacturing a display panel. This manufacturing method includes:

[0023] A prefabricated board is provided, the prefabricated board including a driving substrate and a plurality of anode electrodes disposed on the driving substrate, and the anode electrodes are electrically connected to the driving substrate;

[0024] A first functional layer is fabricated on a preform plate; the first functional layer includes a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack respectively formed on corresponding anode electrodes;

[0025] A first cathode electrode is fabricated on a first functional layer; the first cathode electrode is formed on a first light-emitting stack and a second light-emitting stack.

[0026] A charge generation layer is fabricated on the first cathode electrode and the third light-emitting stack;

[0027] A second functional layer is fabricated on the charge generation layer; the second functional layer includes a fourth light-emitting stack, the projection of the fourth light-emitting stack on the first functional layer covers the first light-emitting stack, the second light-emitting stack and the third light-emitting stack, and the fourth light-emitting stack has the same color as the third light-emitting stack.

[0028] A second cathode electrode is fabricated on the second functional layer; the second cathode electrode is formed on the third light-emitting stack.

[0029] In some embodiments, the steps of forming a charge generation layer on the first cathode electrode and the third light-emitting stack, and forming a second functional layer on the charge generation layer, are both formed by vapor deposition using a cathode mask.

[0030] In some embodiments, the step of fabricating a first cathode electrode on the first functional layer includes:

[0031] The first cathode electrode is deposited on the first and second light-emitting stacks by vapor deposition using a first cathode mask that matches the first cathode electrode; or...

[0032] A first cathode layer is deposited on the first light-emitting stack, the second light-emitting stack, and the third light-emitting stack by evaporation using a cathode mask;

[0033] A first photoresist layer is coated on the first cathode layer and patterned to expose a portion of the first cathode layer on the third light-emitting stack.

[0034] Remove part of the first cathode layer on the third light-emitting stack;

[0035] Remove the first photoresist layer.

[0036] In some embodiments, the step of fabricating a second cathode electrode on the second functional layer includes:

[0037] The second cathode electrode is deposited at a corresponding position on the third light-emitting layer by vapor deposition using a second cathode mask that matches the second cathode electrode; or,

[0038] A second cathode layer is deposited at corresponding positions on the first, second, and third light-emitting layers by evaporation using a cathode mask.

[0039] A second photoresist layer is coated on the second cathode layer and patterned to expose a portion of the second cathode layer above the first light-emitting stack and the second light-emitting stack.

[0040] Remove a portion of the second cathode layer above the first and second light-emitting stacks;

[0041] Remove the second photoresist layer.

[0042] In some embodiments, the step of fabricating a second cathode electrode on the second functional layer includes:

[0043] A cathode barrier layer is deposited at corresponding positions on the first and second light-emitting stacks by vapor deposition using a first cathode mask that matches the first cathode electrode; the cathode barrier layer repels the gold cathode material.

[0044] A cathode material is vapor-deposited and deposited on top of the third light-emitting layer to form a second cathode electrode.

[0045] To address the aforementioned technical problems, the third technical solution provided in this application is: to provide a display device. The display device includes:

[0046] The display panel is the display panel provided by the above technical solution;

[0047] The control circuit board is electrically connected to the display panel and is used to control the display panel to display corresponding images.

[0048] The beneficial effects of this application: Unlike the prior art, this application provides a display panel, its fabrication method, and a display device. The display panel includes a driving substrate, multiple anode electrodes, a first functional layer, a first cathode electrode, a charge generation layer, a second functional layer, and a second cathode electrode. The first functional layer includes a first light-emitting stack, a second light-emitting stack, and a third light-emitting stack respectively disposed on corresponding anode electrodes. A first electrode is disposed on the first and second light-emitting stacks to form a single-structure first and second light-emitting device. Further, by disposing the charge generation layer on the third light-emitting stack and the first cathode electrode, and by including a fourth light-emitting stack on the charge generation layer, and a second cathode electrode on the second functional layer, with the orthogonal projection of the second cathode electrode onto the first functional layer coinciding with the third light-emitting stack, the third light-emitting stack forms a series-connected light-emitting device through the overlap of the charge generation layer and the fourth light-emitting stack. Furthermore, by making the third and fourth light-emitting stacks the same color, the luminous efficiency and lifespan of the third light-emitting device can be effectively improved, thereby enabling the third light-emitting device to be a blue light-emitting device, thus increasing the overall lifespan of the display panel. Meanwhile, by having the orthogonal projection of the fourth light-emitting layer onto the first functional layer cover the first, second, and third light-emitting layers, i.e., the pattern of the fourth light-emitting layer is the same as the cathode pattern, it can be fabricated using a common metal mask (CMM) vapor deposition. Specifically, the fourth light-emitting layer can be fabricated using a cathode mask, eliminating the need for a separate mask specifically for fabricating the fourth light-emitting layer, and requiring only at least four CMM vapor depositions. This reduces costs while also improving product yield. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0050] Figure 1 This is a cross-sectional structural diagram of a display panel provided in an embodiment of the prior art;

[0051] Figure 2 This is a cross-sectional structural diagram of a display panel provided in one embodiment of this application;

[0052] Figure 3 This is a cross-sectional structural diagram of a display panel provided in another embodiment of this application;

[0053] Figure 4 This is a schematic flowchart of a method for manufacturing a display panel according to an embodiment of this application;

[0054] Figure 5 This is a schematic flowchart of a method for preparing a first cathode electrode according to an embodiment of this application;

[0055] Figure 6 This is a schematic flowchart of a method for preparing a second cathode electrode according to an embodiment of this application;

[0056] Figure 7 This is a schematic flowchart of a method for preparing a second cathode electrode according to another embodiment of this application;

[0057] Figure 8 This is a schematic diagram of the structure of a display device provided in an embodiment of this application.

[0058] Figure label:

[0059] 100a, Display panel; 10a, Driving substrate; 21a, First light-emitting unit; 211a, First anode; 212a, First functional layer; 213a, Second functional layer; 22a, Second light-emitting unit; 221a, Second anode; 222a, Third functional layer; 223a, Fourth functional layer; 23a, Third light-emitting unit; 231a, Third anode; 232a, Fifth functional layer; 233a, Sixth functional layer; 24a, Charge generation layer; 25a, Cathode;

[0060] 100. Display panel; 10. Driving substrate; 11. Substrate; 12. Driving circuit layer; 21. Anode electrode; 22. First functional layer; 221. Hole injection layer; 222. First hole transport layer; 223. First light-emitting stack; 2231. First electron blocking layer; 2232. Red light-emitting layer; 224. Second light-emitting stack; 2241. Second electron blocking layer; 2242. Green light-emitting layer; 225. Third light-emitting stack; 2251. Third electron blocking layer; 2252. First blue light-emitting layer; 226. First hole blocking layer; 227. 1. Electron transport layer; 23. First cathode electrode; 24. Charge generation layer; 241. N-type charge generation layer; 242. P-type charge generation layer; 25. Second functional layer; 251. Second hole transport layer; 252. Fourth light-emitting layer; 2521. Fourth electron blocking layer; 2522. Second blue light-emitting layer; 253. Second hole blocking layer; 254. Second electron transport layer; 26. Second cathode electrode; 27. Isolation structure; 271. Pixel aperture; 200. Control circuit board; P1 - First sub-pixel; P2 - Second sub-pixel; P3 - Third sub-pixel. Detailed Implementation

[0061] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0062] In the following description, specific details such as particular system architectures, interfaces, and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0063] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0064] The terms "first," "second," and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0065] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0066] Please see Figure 1 , Figure 1 This is a cross-sectional structural diagram of a display panel provided in an embodiment of the prior art. In the prior art, in order to improve the lifespan of each light-emitting device on the display panel 100a and meet the requirements of medium-sized products, the light-emitting devices are usually fabricated in a stacked and connected structure. As shown in the figure, the display panel 100a includes a driving substrate 10a and a first light-emitting unit 21a, a second light-emitting unit 22a and a third light-emitting unit 23a disposed on the driving substrate 10a.

[0067] The first light-emitting unit 21a includes a first anode 211a, a first functional layer 212a, a charge-generating layer 24a, a second functional layer 213a, and a cathode 25a, which are sequentially stacked along a direction away from the driving substrate 10a. Both the first functional layer 212a and the second functional layer 213a include a red light-emitting layer.

[0068] The second light-emitting unit 22a includes a second anode 221a, a third functional layer 222a, a charge-generating layer 24a, a fourth functional layer 223a, and a cathode 25a, which are sequentially stacked along a direction away from the driving substrate 10a. The third functional layer 222a and the fourth functional layer 223a both include a green light-emitting layer.

[0069] The third light-emitting unit 23a includes a third anode 231a, a fifth functional layer 232a, a charge-generating layer 24a, a sixth functional layer 233a, and a cathode 25a, which are sequentially stacked along a direction away from the driving substrate 10a. The fifth functional layer 232a and the sixth functional layer 233a both include a blue light-emitting layer.

[0070] As can be seen, by configuring the first light-emitting unit 21a, the second light-emitting unit 22a, and the third light-emitting unit 23a as described above, a light-emitting device with a stacked series structure is formed, thereby improving the lifespan of each light-emitting device to meet the requirements of medium-sized panels. However, compared to the traditional single-layer light-emitting layer structure, the stacked series structure of the first light-emitting unit 21a, the second light-emitting unit 22a, and the third light-emitting unit 23a requires an additional light-emitting functional layer process for each color light-emitting unit, thus requiring more layers of FMM evaporation. This not only increases product cost but also easily reduces product yield.

[0071] To address the aforementioned technical problems, this application provides a display panel, its manufacturing method, and a display device, as detailed below.

[0072] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0073] Please see Figure 2 , Figure 2 This is a cross-sectional structural schematic diagram of a display panel provided in an embodiment of this application. In this embodiment, a display panel 100 is provided, which includes:

[0074] Drive substrate 10;

[0075] Multiple anode electrodes 21 are arranged in an array on the driving substrate 10 and are electrically connected to the driving substrate 10.

[0076] The first functional layer 22 includes a first light-emitting stack 223, a second light-emitting stack 224 and a third light-emitting stack 225, which are respectively disposed on the corresponding anode electrode 21;

[0077] The first cathode electrode 23 is disposed on the first light-emitting stack 223 and the second light-emitting stack 224;

[0078] A charge generation layer 24 is disposed on the third light-emitting stack 225 and the first cathode electrode 23;

[0079] The second functional layer 25 includes a fourth light-emitting stack 252, which is disposed on the charge generation layer 24 and whose orthogonal projection on the first functional layer 22 covers the first light-emitting stack 223, the second light-emitting stack 224 and the third light-emitting stack 225; the fourth light-emitting stack 252 has the same color as the third light-emitting stack 225.

[0080] The second cathode electrode 26 is disposed on the second functional layer 25, and the orthogonal projection of the second cathode electrode 26 on the first functional layer 22 coincides with the third light-emitting stack 225.

[0081] The driving substrate 10 includes a substrate 11 and a driving circuit layer 12. The substrate 11 supports the driving circuit layer 12 and each sub-pixel. The substrate 11 can be a glass substrate, a silicon substrate, or a flexible substrate, depending on the specific requirements. The driving circuit layer 12 is disposed on the substrate 11 and includes multiple sub-pixel driving circuits (not shown) for driving the sub-pixels to emit light. Specifically, each sub-pixel driving circuit consists of at least one semiconductor driving device and at least one energy storage device to provide driving signals to the sub-pixels to drive them to emit light.

[0082] Multiple anode electrodes 21 are arrayed on the driving substrate 10. The anode electrodes 21 are disposed on the driving circuit layer 12 and electrically connected to the corresponding sub-pixel driving circuit, specifically serving as the anode of the sub-pixel. The material of the anode electrodes 21 may include one or a combination of metal, metal oxide, or both; the metal material may be conductive metal materials such as gold (Au), silver (Ag), copper (Cu), and aluminum (Al), and the metal oxide may be conductive metal oxide materials such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium zinc oxide (IGZO). For example, the anode electrodes 21 may be a multilayer structure of ITO layer-metal layer-ITO layer, which can be specifically configured according to actual needs. The anode electrodes 21 may be formed by patterning processes, such as photolithography or vapor deposition.

[0083] The first functional layer 22 is disposed on the anode electrode 21, specifically on the side of the anode electrode 21 away from the driving substrate 10. The first functional layer 22 includes a first light-emitting stack 223, a second light-emitting stack 224, and a third light-emitting stack 225, each disposed on its corresponding anode electrode 21. Specifically, the first light-emitting stack 223 and its corresponding anode electrode 21 form a first sub-pixel P1, the second light-emitting stack 224 and its corresponding anode electrode 21 form a second sub-pixel P2, and the third light-emitting stack 225 and its corresponding anode electrode 21 form a third sub-pixel P3.

[0084] It should be noted that on the display panel 100, the area where the first light-emitting stack 223 is located is used to form the first sub-pixel P1, the area where the second light-emitting stack 224 is located is used to form the second sub-pixel P2, and the area where the third light-emitting stack 225 is located is used to form the third sub-pixel P3.

[0085] The first cathode electrode 23 is disposed on one side of the source driving substrate 10 of the first functional layer 22. Specifically, the first cathode electrode 23 is disposed on the first light-emitting stack 223 and the second light-emitting stack 224, that is, the orthogonal projection of the first cathode electrode 23 on the first functional layer 22 coincides with the first light-emitting stack 223 and the second light-emitting stack 224. In this way, the anode electrode 21, the first light-emitting stack 223 and the other film layers of the first functional layer 22, and the first cathode electrode 23 located in the first sub-pixel P1 region constitute a single-layer light-emitting layer structure for the first sub-pixel P1, and the anode electrode 21, the second light-emitting stack 224 and the other film layers of the first functional layer 22, and the first cathode electrode 23 located in the second sub-pixel P2 region constitute a single-layer light-emitting layer structure for the second sub-pixel P2. Specifically, the material of the first cathode electrode 23 can be a metal or an alloy; the metal material can be a low work function conductive metal such as aluminum (Al), silver (Ag), lithium (Li), magnesium (Mg), calcium (Ca), indium (In) to facilitate electron injection; the alloy material can be an alloy of a reactive low work function metal such as magnesium-silver alloy (Mg:Ag) or lithium-aluminum alloy (Li:Al) and a chemically stable high work function metal.

[0086] The charge generation layer 24 is disposed on the third light-emitting stack 225 and the first cathode electrode 23. Specifically, the charge generation layer 24 includes an N-type charge generation layer 241 and a P-type charge generation layer 242 stacked together; wherein the N-type charge generation layer 241 has the function of generating electrons and transferring electrons to the corresponding film layer, and the P-type charge generation layer 242 has the function of generating holes and transferring holes to the corresponding film layer.

[0087] The second functional layer 25 is disposed on the charge generation layer 24, specifically on the side of the charge generation layer 24 away from the driving substrate 10. The second functional layer 25 includes a fourth light-emitting stack 252, the orthogonal projection of which covers the first light-emitting stack 223, the second light-emitting stack 224, and the third light-emitting stack 225 on the first functional layer 22. The charge generation layer 24 and the second functional layer 25 located in the first sub-pixel P1 region can serve as light-emitting layers for the first sub-pixel P1, and the charge generation layer 24 and the second functional layer 25 located in the second sub-pixel P2 region can serve as light-emitting layers for the second sub-pixel P2. These light-emitting layers can be used for dimming to improve the brightness of the first sub-pixel P1 and the second sub-pixel P2.

[0088] The second cathode electrode 26 is disposed on the second functional layer 25, and its orthogonal projection onto the first functional layer 22 coincides with the third light-emitting stack 225. That is, the second cathode electrode 26 is disposed in the third sub-pixel P3 region, forming the third sub-pixel P3 with each functional film layer located in the third pixel region. In the third sub-pixel P3 region, the second cathode electrode 26 and the second functional layer 25 are connected in series with the first functional layer 22 and the anode electrode 21 through the charge generation layer 24 to form a series structure of the third sub-pixel P3. The color of the fourth light-emitting stack 252 is the same as the color of the third light-emitting stack 225, thereby improving the brightness of the luminous efficiency of the third sub-pixel P3 and increasing its lifespan. Furthermore, the third sub-pixel P3 can also be a blue sub-pixel, which can improve the luminous efficiency and lifespan of the blue sub-pixel, thereby increasing the overall lifespan of the display panel 100.

[0089] In this embodiment, through the above-described configuration, the orthogonal projection of the fourth light-emitting layer 252 onto the first functional layer 22 covers the first light-emitting layer 223, the second light-emitting layer 224, and the third light-emitting layer 225. That is, the pattern of the fourth light-emitting layer 252 is the same as the cathode pattern. It can be fabricated using a common metal mask (CMM) vapor deposition. Specifically, a cathode mask can be used to fabricate the fourth light-emitting layer 252, eliminating the need for a separate mask specifically for its fabrication, thus reducing product costs. Furthermore, since the tandem structure only requires CMM vapor deposition of the fourth light-emitting layer 252, requiring only at least four CMM depositions, there is no need for etching followed by vapor deposition of other colored light-emitting layers. This reduces costs while also improving product yield.

[0090] In some embodiments, the first light-emitting stack 223 includes a red light-emitting layer 2232, the second light-emitting stack 224 includes a green light-emitting layer 2242, the third light-emitting stack 225 includes a first blue light-emitting layer 2252, and the fourth light-emitting stack 252 includes a second blue light-emitting layer 2522.

[0091] Specifically, the first light-emitting stack 223 is located in the first sub-pixel P1 region, the second light-emitting stack 224 is located in the second sub-pixel P2 region, and the third light-emitting stack 225 and the fourth light-emitting stack 252 are located in the third sub-pixel P3 region; that is, the first sub-pixel P1 is a red sub-pixel, the second sub-pixel P2 is a green sub-pixel, and the third sub-pixel P3 is a blue sub-pixel. This makes the blue sub-pixel a series-connected light-emitting device, while the red and green sub-pixels are single-layer light-emitting devices. This improves the luminous efficiency and lifespan of the blue sub-pixel, making the lifespan of the blue sub-pixel closer to and more balanced with that of the red and green sub-pixels. This mitigates the impact on the overall lifespan of the display panel 100 caused by the low luminous efficiency and lifespan of the blue sub-pixel.

[0092] In some embodiments, the first light-emitting stack 223 further includes a first electron blocking layer 2231 located between the anode electrode 21 and the red light-emitting layer 2232; the second light-emitting stack 224 further includes a second electron blocking layer 2241 located between the anode electrode 21 and the green light-emitting layer 2242; the third light-emitting stack 225 further includes a third electron blocking layer 2251 located between the anode electrode 21 and the first blue light-emitting layer 2252; and the fourth light-emitting stack 252 further includes a fourth electron blocking layer 2521 located between the charge-generating layer 24 and the second blue light-emitting layer 2522.

[0093] The first functional layer 22 further includes a hole injection layer 221 and a first hole transport layer 222 stacked between the anode electrode 21 and the first light-emitting stack 223 to the third light-emitting stack 225, as well as a first hole blocking layer 226 and a first electron transport layer 227 stacked between the first light-emitting stack 223 to the third light-emitting stack 225 and the first cathode electrode 23.

[0094] The second functional layer 25 further includes a second hole transport layer 251 stacked between the charge generation layer 24 and the fourth light-emitting layer 252, and a second hole blocking layer 253 and a second electron transport layer 254 stacked between the fourth light-emitting layer 252 and the second cathode electrode 26.

[0095] That is, in the first functional layer 22, the three sub-pixels share the hole injection layer 221, the first hole transport layer 222, the first hole blocking layer 226, and the first electron transport layer 227. Considering the microcavity effect of the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3, to ensure that the light color of each sub-pixel meets the product's light emission requirements, the thickness of the first hole transport layer 222 can be correspondingly reduced, while the thickness of the first electron blocking layer 2231 and the second electron blocking layer 2241 can be correspondingly increased. The specific reduction and increase dimensions can be determined according to spectral requirements to adjust the position of the microcavity and the intensity of the microcavity effect, thereby ensuring that the light color meets the product's requirements.

[0096] The second hole transport layer 251, the fourth electron blocking layer 2521, the second blue light emitting layer 2522, the second hole blocking layer 253, and the second electron transport layer 254 of the second functional layer 25 can all be formed by sequential vapor deposition using the CMM method, so as to reduce the number of vapor depositions, reduce the difficulty of process manufacturing, and improve product yield.

[0097] In some embodiments, the first functional film layer may not include the first hole transport layer 222, the first electron blocking layer 2231, the second electron blocking layer 2241, the third electron blocking layer 2251, the first hole blocking layer 226, and the first electron transport layer 227, as required by actual needs. Similarly, the second functional film layer may not include the second hole transport layer 251, the fourth electron blocking layer 2521, the second hole blocking layer 253, and the second electron transport layer 254, as required by specific needs.

[0098] Please see Figure 3 , Figure 3 This is a cross-sectional structural schematic diagram of a display panel provided in another embodiment of this application. In this embodiment, the display panel 100 further includes an isolation structure 27, which is disposed on the driving substrate 10 and has a plurality of pixel openings 271, which expose a first sub-pixel P1, a second sub-pixel P2 and a third sub-pixel P3.

[0099] The first sub-pixel P1 includes a first light-emitting stack 223 with a corresponding anode electrode 21 and a corresponding first cathode electrode 23, as well as a partial charge-generating layer 24 and a partial fourth light-emitting stack 252 located within the corresponding pixel opening 271; the second sub-pixel P2 includes a second light-emitting stack 224 with a corresponding anode electrode 21 and a corresponding first cathode electrode 23, as well as a partial charge-generating layer 24 and a partial fourth light-emitting stack 252 located within the corresponding pixel opening 271; the third sub-pixel P3 includes a third light-emitting stack 225 with a corresponding anode electrode 21, a fourth light-emitting stack 252, as well as a partial charge-generating layer 24 and a second cathode electrode 26 located within the pixel opening 271.

[0100] Specifically, an isolation structure 27 is provided on the driving substrate 10. By making the isolation structure 27 have multiple pixel openings 271 and exposing the first sub-pixel P1, the second sub-pixel P2 and the third sub-pixel P3 through the pixel openings 271, the isolation structure 27 separates sub-pixels of different colors to avoid lateral crosstalk between sub-pixels of different colors.

[0101] Specifically, when fabricating the display panel 100, an anode electrode 21 can first be formed on the driving substrate 10. Then, an isolation structure 27 can be formed on the driving substrate 10 through a patterning process. The isolation structure 27 has multiple pixel openings 271, which expose each anode electrode 21. By first forming the isolation structure 27 on the driving substrate 10, the isolation structure 27 can act as a barrier when the light-emitting layers of different colors are subsequently deposited, thus separating the light-emitting layers of different colors and preventing color bleeding caused by overlapping between the light-emitting layers of different colors.

[0102] In some embodiments, the isolation structure 27 may include a pixel definition layer, which may be formed by photolithography patterning. The specific shape of the pixel definition layer may be set according to actual needs, for example, the shape in the longitudinal section may be a rectangle, a regular trapezoid, or an inverted trapezoid, which may be set according to the manufacturing process and is not specifically limited thereto.

[0103] In some embodiments, the display panel 100 further includes a sealing layer disposed on the second functional layer 25 and the second cathode electrode 26. The sealing layer can be used to encapsulate the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3, and can also serve as a light-emitting layer for the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3. Specifically, the sealing layer can be an inorganic insulating layer, and by using sealing layers with different compositions, the refractive index of the sealing layer can be controlled, thereby further adjusting the light-emitting direction and brightness of the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3, and improving the display effect of the display panel 100.

[0104] The display panel 100 provided in the above embodiments can be prepared using the manufacturing method provided in the following embodiments. Please refer to the following description for details.

[0105] Please see Figure 4 , Figure 4 This is a schematic flowchart of a method for manufacturing a display panel according to an embodiment of this application. In this embodiment, a method for manufacturing a display panel 100 is provided, the method comprising:

[0106] S1: Provide a prefabricated plate, the prefabricated plate including a driving substrate 10 and a plurality of anode electrodes 21 disposed on the driving substrate 10, and the anode electrodes 21 are electrically connected to the driving substrate 10.

[0107] S2: Fabricate a first functional layer 22 on the preform plate; the first functional layer 22 includes a first light-emitting stack 223, a second light-emitting stack 224 and a third light-emitting stack 225 respectively formed on the corresponding anode electrode 21;

[0108] S3: A first cathode electrode 23 is fabricated on the first functional layer 22; the first cathode electrode 23 is formed on the first light-emitting stack 223 and the second light-emitting stack 224;

[0109] S4: A charge generation layer 24 is fabricated on the first cathode electrode 23 and the third light-emitting stack 225;

[0110] S5: A second functional layer 25 is fabricated on the charge generation layer 24; the second functional layer 25 includes a fourth light-emitting stack 252, the projection of the fourth light-emitting stack 252 on the first functional layer 22 covers the first light-emitting stack 223, the second light-emitting stack 224 and the third light-emitting stack 225, and the fourth light-emitting stack 252 has the same color as the third light-emitting stack 225.

[0111] S6: A second cathode electrode 26 is fabricated on the second functional layer 25; the second cathode electrode 26 is formed on the third light-emitting stack 225.

[0112] In step S2, a hole injection layer 221 and a first hole transport layer 222 are sequentially deposited on a prefabricated plate by vapor deposition. This can be done using a cathode mask or by directly depositing the entire surface to form the hole injection layer 221 and the first hole transport layer 222. Then, a first electron blocking layer 2231 and a red light-emitting layer 2232, a second electron blocking layer 2241 and a green light-emitting layer 2242, a third electron blocking layer 2251 and a first blue light-emitting layer 2252 are deposited by vapor deposition using masks corresponding to the respective colors of the light-emitting layers. Next, a first hole blocking layer 226 and a first electron blocking layer 2231 are sequentially deposited by vapor deposition. This can be done using a cathode mask or by directly depositing the entire surface to form the entire surface of the first hole blocking layer 226 and the first electron transport layer 227. This completes the fabrication of the first functional layer 22.

[0113] In step S3, a first cathode electrode 23 is prepared by vapor deposition, so that the first cathode electrode 23 is formed on the first light-emitting stack 223 and the second light-emitting stack 224, thereby forming a first light-emitting device and a second light-emitting device with a single-layer light-emitting structure.

[0114] In step S4, an N-type charge generation layer 241 and a P-type charge generation layer 242 are sequentially formed by vapor deposition to prepare a charge generation layer 24, which serves as the connection structure of the series structure in the third sub-pixel P3.

[0115] In step S5, a second hole transport layer 251, a fourth electron blocking layer 2521, a second blue luminescent layer 2522, a second hole blocking layer 253, and a second electron transport layer 254 are sequentially deposited on the charge generation layer 24, thereby completing the fabrication of the second functional layer 25. Specifically, each layer of the second functional layer 25 can be formed by vapor deposition using a cathode mask, eliminating the need for a separate mask and reducing product manufacturing costs; moreover, it reduces the number of vapor deposition cycles, simplifying the process and effectively improving product yield.

[0116] In step S6, a second cathode electrode 26 is formed on the second functional layer 25 by vapor deposition or photolithography. The second cathode electrode 26 is formed in the third sub-pixel P3 region, thereby forming a complete series structure of the third sub-pixel P3 in the third sub-pixel P3 region.

[0117] The display panel 100 manufactured using the above method can effectively improve the luminous efficiency and lifespan of the third sub-pixel P3. By making the third sub-pixel P3 a blue sub-pixel, the luminous efficiency and lifespan of the blue sub-pixel can be effectively improved, thus making the lifespan of the blue sub-pixel closer to that of the red and green sub-pixels, thereby increasing the lifespan of the display panel 100. Simultaneously, using the above method to manufacture the display panel 100 can reduce manufacturing costs, simplify the process, and improve product yield.

[0118] In some embodiments, both step S4, which involves fabricating the charge generation layer 24 on the first cathode electrode 23 and the third light-emitting stack 225, and step S5, which involves fabricating the second functional layer 25 on the charge generation layer 24, are formed by vapor deposition using a cathode mask. This eliminates the need for a dedicated mask to fabricate the charge generation layer 24 and the second functional layer 25, thus saving on the manufacturing cost of the display panel 100.

[0119] In some embodiments, step S3, which involves fabricating a first cathode electrode 23 on the first functional layer 22, includes depositing the first cathode electrode 23 on the first light-emitting stack 223 and the second light-emitting stack 224 by vapor deposition using a first cathode mask that matches the first cathode electrode 23.

[0120] That is, when fabricating the first cathode electrode 23, a first cathode mask matching the first cathode electrode 23 can be used, specifically formed by FMM vapor deposition. It should be noted that, in order to reduce the problem of damage to the mask during the high-temperature Ag metal process, the material of the first cathode electrode 23 can be a CEM low-temperature process material, that is, a material used in a polar chemical vapor deposition process at a temperature that is raised but below the melting point of the substrate, specifically at a process temperature of around 600°C.

[0121] Please see Figure 5 , Figure 5 This is a schematic flowchart of a method for preparing a first cathode electrode according to an embodiment of this application. In some embodiments, step S3 may specifically include the following steps:

[0122] S31: A first cathode layer is deposited on the first light-emitting stack 223, the second light-emitting stack 224 and the third light-emitting stack 225 by evaporation through a cathode mask;

[0123] S32: A first photoresist layer is coated on the first cathode layer and patterned to expose a portion of the first cathode layer on the third light-emitting stack 225.

[0124] S33: Remove part of the first cathode layer on the third light-emitting stack 225;

[0125] S34: Remove the first photoresist layer.

[0126] In some embodiments, a cathode mask can be used for vapor deposition to form a full-surface first cathode layer. Then, a portion of the first cathode layer located in the third sub-pixel P3 region is removed by etching, thereby forming the first cathode electrode 23 described in the above embodiments. It should be noted that, to reduce the impact of the etching process on the underlying organic film layer, the underlying first electron transport layer 227 can be fabricated using an etching-resistant material. This fabrication method for the first cathode electrode 23 eliminates the need for an additional FMM (Foil Model) matching the pattern of the first cathode electrode 23, thus saving manufacturing costs.

[0127] In some embodiments, step S6 of fabricating the second cathode electrode 26 on the second functional layer 25 includes: depositing the second cathode electrode 26 at a corresponding position on the third light-emitting stack 225 by vapor deposition using a second cathode 26 mask that matches the second cathode electrode 26.

[0128] That is, similar to the first cathode electrode 23, a second cathode 26 mask matching the second cathode electrode 26 can be used, specifically formed by FMM vapor deposition. It should be noted that, to reduce the problem of Ag metal high-temperature process damaging the mask, the material of the second cathode electrode 26 can be a CEM low-temperature process material, that is, a material used in a polar chemical vapor deposition process at a temperature that is raised but below the substrate melting point, specifically at a process temperature of around 600°C.

[0129] Please see Figure 6 , Figure 6 This is a schematic flowchart of a method for preparing a second cathode electrode according to an embodiment of this application. In some embodiments, step S6 may specifically include the following steps:

[0130] S61: A second cathode 26 layer is deposited at corresponding positions on the first light-emitting stack 223, the second light-emitting stack 224 and the third light-emitting stack 225 by evaporation through a cathode mask.

[0131] S62: A second photoresist layer is coated on the second cathode 26 layer and patterned to expose a portion of the second cathode 26 layer above the first light-emitting stack 223 and the second light-emitting stack 224.

[0132] S63: Remove a portion of the second cathode 26 layer above the first light-emitting stack 223 and the second light-emitting stack 224;

[0133] S64: Remove the second photoresist layer.

[0134] and Figure 5 Similarly, in some embodiments, a cathode mask can be used for vapor deposition to form a full-surface second cathode layer 26. Then, a portion of the second cathode layer 26 located in the first sub-pixel P1 region and the second sub-pixel P2 region is removed by etching, thereby forming the second cathode electrode 26 described in the above embodiments. It should be noted that, to reduce the impact of the etching process on the underlying organic film layer, the underlying second electron transport layer 254 can be fabricated using an etching-resistant material. This fabrication method for the second cathode electrode 26 eliminates the need for an additional FMM (Foil Model) matching the pattern of the second cathode electrode 26, thus saving manufacturing costs.

[0135] Please see Figure 7 , Figure 7 This is a schematic flowchart of a method for preparing a second cathode electrode according to another embodiment of this application. In some embodiments, step S6 may specifically include the following steps:

[0136] S65: A cathode blocking layer is deposited at corresponding positions on the first light-emitting stack 223 and the second light-emitting stack 224 by vapor deposition using a first cathode mask that matches the first cathode electrode 23; the cathode blocking layer repels the cathode material.

[0137] S66: Vaporized cathode material is deposited on the third light-emitting stack 225 to form a second cathode electrode 26.

[0138] The cathode barrier layer repels the cathode material, preventing the cathode material from adhering to the cathode barrier layer. Therefore, when the cathode barrier layer is deposited first in the first and second sub-pixel regions, and then the cathode material is vaporized, the cathode material cannot be deposited in the first and second sub-pixel regions, but can only be deposited in the third sub-pixel region, thus forming the second cathode electrode 26.

[0139] The cathode material may specifically include a metallic material, and the cathode barrier layer may be a cathode patterning material (CPM). The CPM material is incompatible with the metallic material and repels it, thus causing the cathode barrier layer formed by the CPM material to repel the cathode material. In some embodiments, the CPM material is a fluorinated organic material, such as a homosubstituted fluorinated triphosphonium compound. The CPM material can be deposited in the first and second sub-pixel regions by low-temperature vacuum evaporation to form the aforementioned cathode barrier layer. In other embodiments, the CPM material may not be a fluorinated organic material, as long as the CPM material is incompatible with the metallic material and repels it.

[0140] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of a display device provided in one embodiment of this application. In this embodiment, a display device is provided that can be used in display fields such as tablets, mobile phones, automotive displays, VR glasses, and lighting equipment.

[0141] The display device includes a display panel 100 and a control circuit board 200. The control circuit board 200 is electrically connected to the display panel 100 and provides various drive signals, power signals, and other drive signals required by the display panel 100, thereby controlling the display panel 100 to display corresponding images. The specific structure and function of the display panel 100 are the same as or similar to those of the display panel 100 in the above embodiments, and can achieve the same technical effects; please refer to the relevant description above for details.

[0142] The above are merely embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A display panel, comprising: a driving substrate; a plurality of anode electrodes arranged in an array on the driving substrate and electrically connected with the driving substrate; a first functional layer comprising a first light-emitting stack, a second light-emitting stack and a third light-emitting stack, which are respectively arranged on corresponding anode electrodes; a first cathode electrode arranged on the first light-emitting stack and the second light-emitting stack; characterized in that the display panel further comprises: a charge generation layer arranged on the third light-emitting stack and the first cathode electrode; a second functional layer comprising a fourth light-emitting stack, which is arranged on the charge generation layer and whose orthographic projection on the first functional layer covers the first light-emitting stack, the second light-emitting stack and the third light-emitting stack; the fourth light-emitting stack has the same color as the third light-emitting stack; and a second cathode electrode arranged on the second functional layer, and whose orthographic projection on the first functional layer only coincides with the third light-emitting stack. The first light-emitting stack comprises a red light-emitting layer, the second light-emitting stack comprises a green light-emitting layer, the third light-emitting stack comprises a first blue light-emitting layer, and the fourth light-emitting stack comprises a second blue light-emitting layer. The first light-emitting stack further comprises a first electron blocking layer between the anode electrode and the red light-emitting layer; the second light-emitting stack further comprises a second electron blocking layer between the anode electrode and the green light-emitting layer; the third light-emitting stack further comprises a third electron blocking layer between the anode electrode and the first blue light-emitting layer; and the fourth light-emitting stack further comprises a fourth electron blocking layer between the charge generation layer and the second blue light-emitting layer. The first functional layer further comprises a hole injection layer and a first hole transport layer which are arranged in a stack and between the anode electrode and the first light-emitting stack to the third light-emitting stack, and a first hole blocking layer and a first electron transport layer which are arranged in a stack and between the first light-emitting stack to the third light-emitting stack and the first cathode electrode. The second functional layer further comprises a second hole transport layer which is arranged in a stack and between the charge generation layer and the fourth light-emitting stack, and a second hole blocking layer and a second electron transport layer which are arranged in a stack and between the fourth light-emitting stack and the second cathode electrode. The display panel further comprises an isolation structure arranged on the driving substrate and having a plurality of pixel openings, which expose a first sub-pixel, a second sub-pixel and a third sub-pixel. The first sub-pixel comprises the first light-emitting stack, corresponding anode electrode and corresponding first cathode electrode, and part of the charge generation layer and part of the fourth light-emitting stack which are located in corresponding pixel openings. The second sub-pixel comprises the second light-emitting stack, corresponding anode electrode and corresponding first cathode electrode, and part of the charge generation layer and part of the fourth light-emitting stack which are located in corresponding pixel openings. ​ ​ ​ ​ ​ ​ ​ ​ 2. The display panel of claim 1, wherein, ​ 3. The display panel of claim 2, wherein, ​ ​ ​ 4. The display panel of claim 1, wherein, ​ ​ ​ The third sub-pixel comprises the third light-emitting stack and the corresponding anode electrode, the fourth light-emitting stack, and part of the charge generation layer and the second cathode electrode located in the pixel opening.

5. A method for manufacturing a display panel, characterized by, Comprise: A prefabricated plate is provided, which comprises a driving substrate and a plurality of anode electrodes disposed on the driving substrate, and the anode electrodes are electrically connected with the driving substrate; A first functional layer is made on the prefabricated plate; the first functional layer comprises a first light-emitting stack, a second light-emitting stack and a third light-emitting stack formed on the corresponding anode electrode respectively; A first cathode electrode is made on the first functional layer; The first cathode electrode is formed on the first light-emitting stack and the second light-emitting stack; A charge generation layer is made on the first cathode electrode and the third light-emitting stack; A second functional layer is made on the charge generation layer; the second functional layer comprises a fourth light-emitting stack, the projection of the fourth light-emitting stack on the first functional layer covers the first light-emitting stack, the second light-emitting stack and the third light-emitting stack, and the fourth light-emitting stack is the same color as the third light-emitting stack; A second cathode electrode is made on the second functional layer; The second cathode electrode is only formed on the third light-emitting stack.

6. The method of manufacturing a display panel according to claim 5, wherein, The step of making a charge generation layer on the first cathode electrode and the third light-emitting stack, and the step of making a second functional layer on the charge generation layer, are both formed by evaporation through a cathode mask.

7. The method of manufacturing a display panel according to claim 5, wherein The step of making a first cathode electrode on the first functional layer comprises: Depositing the first cathode electrode on the first light-emitting stack and the second light-emitting stack by evaporation through a first cathode mask matched with the first cathode electrode; or, Depositing a first cathode layer on the first light-emitting stack, the second light-emitting stack and the third light-emitting stack by evaporation through a cathode mask; A first photoresist layer is coated on the first cathode layer and is patterned to expose part of the first cathode layer on the third light-emitting stack; Part of the first cathode layer on the third light-emitting stack is removed; The first photoresist layer is removed.

8. The method of manufacturing a display panel according to claim 5, wherein, The step of making a second cathode electrode on the second functional layer comprises: Depositing the second cathode electrode on the corresponding position above the third light-emitting stack by evaporation through a second cathode mask matched with the second cathode electrode; or, Depositing a second cathode layer on the corresponding position above the first light-emitting stack, the second light-emitting stack and the third light-emitting stack by evaporation through a cathode mask; A second photoresist layer is coated on the second cathode layer and is patterned to expose part of the second cathode layer above the first light-emitting stack and the second light-emitting stack; Part of the second cathode layer above the first light-emitting stack and the second light-emitting stack is removed; The second photoresist layer is removed.

9. The method of manufacturing a display panel according to claim 5, wherein, The step of making a second cathode electrode on the second functional layer comprises: A cathode barrier layer is formed by evaporation through a first cathode mask matching the first cathode electrode, and deposited at a corresponding position above the first light-emitting stack and the second light-emitting stack; the cathode barrier layer is repulsive to the cathode material; A second cathode electrode is formed by evaporation of a cathode material, and deposited at a position above the third light-emitting stack.

10. A display device, characterized by comprising: The display panel comprises: The display panel is as claimed in any one of claims 1-4; The control circuit board is electrically connected with the display panel, and is used for controlling the display panel to display a corresponding image.

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