Display panel and display device

Abstract

The invention discloses a display panel and a display device. The display panel comprises a first electrode, a first light-emitting layer and a second electrode which are sequentially arranged in a stacked mode. The first electrode is configured to inject holes into the first light emitting layer, and the second electrode is configured to inject electrons into the first light emitting layer. The first light-emitting layer comprises at least two light-emitting sub-layers which are arranged in a stacked mode. The hole mobility of each light-emitting sub-layer is smaller than the electron mobility of the light-emitting sub-layer. The display panel is used for displaying images.

Description

Display panel and display device Technical Field

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

[0002] With the continuous development of display technology, display devices have gradually become ubiquitous in people's lives. Among them, organic light-emitting diode (OLED) display panels are widely used in display devices such as mobile phones, televisions, and laptops due to their advantages such as self-illumination, low power consumption, wide viewing angle, fast response speed, and high contrast.

[0003] Summary of the Invention

[0004] On one hand, a display panel is provided, including a first electrode, a first light-emitting layer, and a second electrode stacked sequentially. The first electrode is configured to inject holes into the first light-emitting layer, and the second electrode is configured to inject electrons into the first light-emitting layer. The first light-emitting layer includes at least two stacked light-emitting sublayers. The hole mobility of each light-emitting sublayer is less than the electron mobility of the light-emitting sublayer.

[0005] In some embodiments, the ratio of electron mobility to hole mobility in each of the light-emitting sublayers is greater than or equal to 10.

[0006] In some embodiments, the first light-emitting layer includes a first light-emitting sublayer and a second light-emitting sublayer adjacent to the first light-emitting sublayer, wherein the first light-emitting sublayer is closer to the first electrode than the second light-emitting sublayer. The thickness of the first light-emitting sublayer is less than the thickness of the second light-emitting sublayer.

[0007] In some embodiments, the thickness of the first light-emitting sublayer is 5 nm to 10 nm.

[0008] In some embodiments, the first light-emitting layer includes a first light-emitting sublayer and a second light-emitting sublayer adjacent to the first light-emitting sublayer, wherein the first light-emitting sublayer is closer to the first electrode than the second light-emitting sublayer. The electron mobility of the second light-emitting sublayer is greater than that of the first light-emitting sublayer.

[0009] In some embodiments, the first light-emitting layer includes at least three light-emitting sub-layers, and the electron mobility of the at least three light-emitting sub-layers increases sequentially along the direction from the first electrode to the second electrode.

[0010] In some embodiments, the first light-emitting layer includes a first light-emitting sublayer and a second light-emitting sublayer adjacent to the first light-emitting sublayer, wherein the first light-emitting sublayer is closer to the first electrode than the second light-emitting sublayer. The hole mobility of the second light-emitting sublayer is greater than or equal to the hole mobility of the first light-emitting sublayer.

[0011] In some embodiments, the first light-emitting layer includes at least three light-emitting sub-layers, and the hole mobility of the at least three light-emitting sub-layers increases sequentially along the direction from the first electrode to the second electrode.

[0012] In some embodiments, the absolute value of the highest occupied molecular orbital energy level of the first luminescent sublayer of the first luminescent layer is less than or equal to the absolute value of the highest occupied molecular orbital energy level of the second luminescent sublayer of the first luminescent layer. The absolute value of the lowest unoccupied molecular orbital energy level of the first luminescent sublayer of the first luminescent layer is less than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the second luminescent sublayer of the first luminescent layer.

[0013] In some embodiments, the display panel further includes a hole transport layer and an electron blocking layer sequentially stacked along a direction away from the first electrode, the hole transport layer and the electron blocking layer being located between the first photonic layer and the first electrode. The absolute value of the highest occupied molecular orbital energy level of the hole transport layer is less than or equal to the absolute value of the highest occupied molecular orbital energy level of the electron blocking layer.

[0014] In some embodiments, the absolute value of the highest occupied molecular orbital energy level of the electron blocking layer is greater than or equal to the absolute value of the highest occupied molecular orbital energy level of the first luminescent sublayer.

[0015] In some embodiments, the display panel further includes a hole blocking layer located between the second light-emitting sublayer and the second electrode. The absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the second light-emitting sublayer.

[0016] In some embodiments, the difference between the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer and the absolute value of the lowest unoccupied molecular orbital energy level of the second photonic sublayer is less than or equal to 0.2 eV.

[0017] In some embodiments, the display panel further includes an electron transport layer located between the hole blocking layer and the second electrode. The absolute value of the lowest unoccupied molecular orbital energy level of the electron transport layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer.

[0018] In some embodiments, the difference between the absolute value of the lowest unoccupied molecular orbital energy level of the electron transport layer and the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer is less than or equal to 0.2 eV.

[0019] In some embodiments, the display panel includes a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer. At least one of the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer is the first light-emitting layer.

[0020] In some embodiments, the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer are all the first light-emitting layer.

[0021] In some embodiments, the display panel includes at least two stacked first light-emitting layers and at least one charge-generating layer. A charge-generating layer is disposed between any two adjacent first light-emitting layers.

[0022] In some embodiments, the display panel further includes a second light-emitting layer and a charge-generating layer, the charge-generating layer being located between the first light-emitting layer and the second light-emitting layer. The second light-emitting layer has a single-layer structure. The second light-emitting layer is closer to or farther from the first electrode than the first light-emitting layer.

[0023] On the other hand, a display device is provided, including a display panel and a cover plate as described in any of the above embodiments. The cover plate is disposed on the light-emitting side of the display panel. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0025] Figure 1 is a structural diagram of a display device according to some embodiments;

[0026] Figure 2 is a cross-sectional view of the display device in Figure 1 along section line BB;

[0027] Figure 3 is a structural diagram of a display panel according to some embodiments;

[0028] Figure 4A is a film structure diagram of a sub-pixel in a display panel according to some embodiments;

[0029] Figure 4B is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0030] Figure 5 is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0031] Figure 6 is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0032] Figure 7A is a graph showing the relationship between voltage and current density of the first color sub-pixel (i.e., the red sub-pixel) in the display panel.

[0033] Figure 7B is a graph showing the relationship between voltage and current density of the second color sub-pixel (i.e., the green sub-pixel) in the display panel.

[0034] Figure 7C is a graph showing the relationship between voltage and current density of the third color sub-pixel (i.e., the blue sub-pixel) in the display panel.

[0035] Figure 8A is a curve showing the relationship between the brightness and efficiency of the first color sub-pixel (i.e., the red sub-pixel) in the display panel.

[0036] Figure 8B is a graph showing the relationship between brightness and efficiency of the second color sub-pixel (i.e., the green sub-pixel) in the display panel.

[0037] Figure 8C is a graph showing the relationship between the brightness and efficiency of the third color sub-pixel (i.e., the blue sub-pixel) in the display panel.

[0038] Figure 9 is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0039] Figure 10A is a curve showing the relationship between the usage time and brightness of the first color sub-pixel (i.e., the red sub-pixel) in the display panel;

[0040] Figure 10B is a curve showing the relationship between the usage time and brightness of the second color sub-pixel (i.e., the green sub-pixel) in the display panel;

[0041] Figure 10C is a curve showing the relationship between the usage time and brightness of the third color sub-pixel (i.e., the blue sub-pixel) in the display panel;

[0042] Figure 11 is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0043] Figure 12 is a schematic diagram of the lowest unoccupied molecular orbital energy level and the highest occupied molecular orbital energy level of the film layer in the sub-pixel of a display panel according to some embodiments;

[0044] Figure 13A is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0045] Figure 13B is another film layer structure diagram of a sub-pixel in a display panel according to some embodiments;

[0046] Figure 13C is a diagram of yet another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0047] Figure 14A is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0048] Figure 14B is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0049] Figure 14C is a diagram of yet another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0050] Figure 15 is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0051] Figure 16A is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0052] Figure 16B is a diagram of another film layer structure of a sub-pixel in a display panel according to some embodiments;

[0053] Figure 17 is a diagram of another film structure of a sub-pixel in a display panel according to some embodiments. Detailed Implementation

[0054] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0055] Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms, such as the third-person singular "comprises" and the present participle "comprising," are interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiments," "example," "specific example," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0056] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0057] In describing some embodiments, the terms "coupled" and "connected," and their derivative expressions, may be used. The term "connected" should be interpreted broadly; for example, a "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection via an intermediate medium. The term "coupled," for example, indicates that two or more components have direct physical or electrical contact. The term "coupled" or "communicatively coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content of this document.

[0058] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0059] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0060] As used herein, depending on the context, the term “if” may optionally be interpreted as meaning “when”, “in the event of”, “in response to determination”, or “in response to detection”. Similarly, depending on the context, the phrase “if it is determined that…” or “if [the stated condition or event] is detected” may optionally be interpreted as meaning “in the event of determination that…”, “in response to determination that…”, “when [the stated condition or event] is detected”, or “in response to the detection of [the stated condition or event]”.

[0061] The use of “applies to” or “configured to” in this article implies an open and inclusive language that does not preclude applicability to or configuration to devices that perform additional tasks or steps.

[0062] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0063] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0064] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable range of deviation, which is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable range of deviation for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable range of deviation for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable range of deviation for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0065] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0066] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0067] For ease of description below, an XYZ coordinate system is established. The third direction Z represents the thickness direction of the display device, the XY plane is perpendicular to the Z direction, and the first direction X intersects the second direction Y. For example, the first direction X and the second direction Y are perpendicular to each other.

[0068] It should be noted that, for example, F1 / F in the accompanying drawings of this disclosure indicates that the component is both F1 and F, and other similar reference numerals in the drawings also follow the above description.

[0069] As shown in FIG1, some embodiments of the present disclosure provide a display device 100.

[0070] Exemplarily, display device 100 can be any device that displays images, whether moving (e.g., video) or stationary (e.g., still images), and whether text or images. More specifically, the embodiments described are contemplated to be implemented in or associated with a variety of electronic devices, such as (but not limited to) mobile phones, wireless devices, personal data assistants (PDAs), handheld or portable computers, GPS receivers / navigators, cameras, MP4 video players, camcorders, game consoles, watches, clocks, calculators, television monitors, flat panel displays, computer monitors, automotive displays (e.g., odometer displays, etc.), navigators, cockpit controllers and / or displays, displays of camera views (e.g., displays of rearview cameras in vehicles), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging and aesthetic structures (e.g., displays of images of a piece of jewelry), etc. Figure 1 illustrates display device 100 as an example of a mobile phone.

[0071] For example, the display device 100 may be an electroluminescent display device or a photoluminescent display device. When the display device 100 is an electroluminescent display device, it may be an organic light-emitting diode (OLED) or a quantum dot light-emitting diode (QLED). When the display device 100 is a photoluminescent display device, it may be a quantum dot photoluminescent display device.

[0072] The following uses an organic light-emitting diode (OLED) display device 100 as an example to illustrate some embodiments of the present disclosure. However, the implementation of the present disclosure includes, but is not limited to, these embodiments. Any other display device can also be considered as long as the same technical concept is applied.

[0073] In some embodiments, as shown in FIG2, FIG2 is a cross-sectional view of the display device 100 in FIG1 along section line BB. The display device 100 includes a display panel 10 and a cover plate 20. The cover plate 20 is disposed on the light-emitting side of the display panel 10.

[0074] The cover plate 20 can isolate the display panel 10 from the external environment and provide protection for the display panel 10.

[0075] For example, the cover plate 20 can be a single-layer cover plate or multiple cover plates 20 bonded together by adhesive.

[0076] For example, the cover plate 20 can be a silicate glass cover plate, such as curved glass or ultra-thin glass.

[0077] The cover plate 20 can also be a flexible polymer film cover plate, such as transparent polyimide, PET or polyurethane.

[0078] The cover plate 20 can also be a combination of the above-mentioned flexible polymer films, or a combination of flexible polymer film and silicate glass.

[0079] In some embodiments, the display device 100 may further include a circuit board (not shown). The circuit board is electrically connected to the display panel 10 and is configured to drive the display panel 10 to display an image.

[0080] For example, circuit boards include, but are not limited to, PCBs (Printed Circuit Boards) and FPCs (Flexible Printed Circuit Boards).

[0081] In some embodiments, the display device 100 may further include an under-display camera and an under-display fingerprint sensor, enabling the display device 100 to perform various functions such as taking photos, recording videos, fingerprint recognition, or facial recognition. This disclosure does not impose any limitations on this, and adaptive designs can be made according to actual needs.

[0082] The display panel 10 described above will be described in detail below.

[0083] In some embodiments, as shown in FIG3, FIG3 is a structural diagram of a display panel 10 according to some embodiments. The display panel 10 can be a rectangular structure.

[0084] It should be noted that the aforementioned "rectangular structure" refers to the fact that the overall shape of the boundary of the display panel 10 is rectangular, but it is not limited to a standard rectangle. That is, the "rectangle" here includes not only the shape of a standard rectangle, but also shapes similar to rectangles, taking into account manufacturing conditions. For example, as shown in Figure 3, the long and short sides of the rectangle are curved at each intersection point (i.e., at the corner G), meaning that the corner G is smooth, making the boundary of the display panel 10 a rounded rectangle in the plan view.

[0085] In other embodiments, the display panel 10 may be a circular structure or other shapes with corners.

[0086] The following uses a rectangular structure for the display panel 10 as an example to illustrate some embodiments of the present disclosure. However, the implementation of the present disclosure includes, but is not limited to, this, and the shape of the display panel 10 can also be any other shape.

[0087] In some embodiments, please continue to refer to FIG3, the display panel 10 has a display area AA for displaying images and a peripheral area AN located on at least one side of the display area AA.

[0088] For example, the peripheral area AN is located on one side of the display area AA.

[0089] For example, the peripheral area AN is located on both sides of the display area AA.

[0090] For example, as shown in Figure 3, the peripheral area AN surrounds the display area AA.

[0091] It should be noted that the specific setting of the peripheral area AN is related to the specific design of the display panel 10, and can be designed according to actual needs. This is only an example and is not intended to limit this disclosure.

[0092] In some embodiments, please continue to refer to Figures 2 and 3. The display area AA of the display panel 10 is provided with a plurality of sub-pixels F, and the sub-pixel F is the smallest light-emitting unit in the display area AA.

[0093] For example, multiple sub-pixels F within the display area AA of the display panel 10 can emit light of the same color. The display panel 10 may also include a color filter layer disposed on the light-emitting side of the multiple sub-pixels F. For instance, the multiple sub-pixels F may emit light of colors such as white, red, green, or blue. In this case, the colored light emitted by the sub-pixels F is emitted as the same color after passing through the color filter layer, or it is converted into other colors and emitted. Thus, when the multiple sub-pixels F emit light of the same color, the display panel 10 can achieve multi-color light emission.

[0094] Alternatively, please refer to Figure 2. Multiple sub-pixels F in the display area AA of the display panel 10 emit light of different colors. For example, the multiple sub-pixels F include a first color sub-pixel F1 that emits light of the first color, a second color sub-pixel F2 that emits light of the second color, and a third color sub-pixel F3 that emits light of the third color, thereby realizing multi-color light emission of the display panel 10.

[0095] In this design, the first color sub-pixel F1 can be a red sub-pixel, emitting red light. The second color sub-pixel F2 can be a green sub-pixel, emitting green light. The third color sub-pixel F3 can be a blue sub-pixel, emitting blue light.

[0096] Alternatively, the first color sub-pixel F1 can also be a green sub-pixel or a blue sub-pixel. The second color sub-pixel F2 can also be a red sub-pixel or a blue sub-pixel. The third color sub-pixel F3 can also be a red sub-pixel or a green sub-pixel.

[0097] The following uses the example of a first color sub-pixel F1 being a red sub-pixel, a second color sub-pixel F2 being a green sub-pixel, and a third color sub-pixel F3 being a blue sub-pixel to illustrate some embodiments of this disclosure. However, the implementation of this disclosure includes, but is not limited to, the first color sub-pixel F1, the second color sub-pixel F2, and the third color sub-pixel F3 can also be sub-pixels of other colors F.

[0098] In some embodiments, referring to FIG2, the display panel 10 includes a substrate 1.

[0099] For example, the material used to form substrate 1 may include inorganic materials, such as glass materials such as soda-lime glass, quartz glass, and sapphire glass.

[0100] The material used to form substrate 1 may also include organic materials, such as one or more of polymethyl methacrylate, polyvinyl alcohol, polyvinylphenol, polyethersulfone, polyimide, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, and polyethylene naphthalate.

[0101] The materials used to form substrate 1 may include both organic and inorganic materials.

[0102] In some embodiments, referring to FIG2, the display panel 10 further includes a pixel driving layer 2 and a light-emitting device layer 3. The pixel driving layer 2 and the light-emitting device layer 3 are located on one side of the substrate 1 and are stacked sequentially in a direction away from the substrate 1. The light-emitting device layer 3 is used to set a plurality of sub-pixels F of the display panel 10. The pixel driving layer 2 is used to drive the plurality of sub-pixels F in the light-emitting device layer 3 to emit light.

[0103] For example, a pixel driving circuit is provided in the pixel driving layer 2. The pixel driving circuit is connected to the sub-pixel F and is used to drive the sub-pixel F to emit light.

[0104] For example, the pixel driving circuit includes multiple transistors. The pixel driving circuit can be a 3T1C, 4T1C, 5T1C, 5T2C, 6T1C, 7T1C, or 8T1C structure. Here, T represents a transistor, and the number preceding T indicates the number of transistors; C represents a capacitor, and the number preceding C indicates the number of capacitors.

[0105] For example, the transistors in the pixel driving circuit can be low-temperature polysilicon (LTPS) transistors, oxide transistors, or a combination of both. The active layer of the LTPS transistor is made of low-temperature polysilicon (LTPS), while the active layer of the oxide transistor is made of oxide semiconductor. LTPS transistors have advantages such as high mobility and fast charging, while oxide transistors have advantages such as low leakage current.

[0106] For example, the transistors in the pixel driving circuit can be top-gate transistors, bottom-gate transistors, or dual-gate transistors.

[0107] For example, the transistor in the pixel driving circuit can be a P-type transistor or an N-type transistor.

[0108] For example, the pixel driving layer 2 may include an active layer formed on the substrate 1 by a patterning process, a gate insulating layer (GI) formed on the active layer by deposition or the like, a gate of a transistor (TFT) formed on the gate insulating layer (GI) by a patterning process, a dielectric layer (ILD) formed on the gate by deposition or the like, a source drain metal layer formed on the dielectric layer (ILD), and a planarization layer (PLN) covering the source drain metal layer and the exposed dielectric layer (ILD), wherein the source drain metal layer forms the source and drain of the transistor (TFT).

[0109] The active layer can be made of polysilicon and metal oxides, the gate insulating layer (GI) can be made of inorganic insulating materials such as silicon oxide, silicon nitride, or silicon oxynitride, and the dielectric layer (ILD) can also be made of inorganic insulating materials such as silicon oxide, silicon nitride, or silicon oxynitride. The gate material can be made of metals or alloys such as aluminum, titanium, or cobalt. The planarization layer (PLN) can be made of organic materials or inorganic insulating materials such as silicon oxide, silicon nitride, or silicon oxynitride. The planarization layer (PLN) has a planarization function, which is beneficial to improving the quality of subsequent material deposition, reducing surface differences of other films formed later, and preventing water and oxygen from entering the multiple sub-pixels F within the light-emitting device layer 3.

[0110] For example, referring to FIG2, the light-emitting device layer 3 includes a first electrode layer 31, a light-emitting functional layer 33, and a second electrode layer 32, which are sequentially stacked along the third direction Z (i.e., the thickness direction of the display device 100). The first electrode layer 31 includes a plurality of first electrodes 311, the light-emitting functional layer 33 includes a plurality of light-emitting parts 331, and the second electrode layer 32 includes a plurality of second electrodes 321.

[0111] The first electrode layer 31 and the second electrode layer 32 can provide charge carriers such as electrons and holes to the light-emitting functional layer 33, so that the light-emitting functional layer 33 emits light. Specifically, the first electrode 311 in the first electrode layer 31 and the second electrode 321 in the second electrode layer 32 can provide charge carriers such as electrons and holes to the light-emitting part 331 in the light-emitting functional layer 33, so that the light-emitting part 331 in the light-emitting functional layer 33 emits light.

[0112] For example, please continue to refer to FIG2, the first electrode layer 31 may be closer to the substrate 1 than the second electrode layer 32.

[0113] In some embodiments, referring to FIG2, the display panel 10 further includes a pixel definition layer (PDL) 4. The pixel definition layer (PDL) 4 is located on the side of the first electrode layer 31 away from the substrate 1. A plurality of pixel openings are formed in the pixel definition layer (PDL) 4, and the pixel openings are correspondingly disposed with respect to the first electrodes 311 in the first electrode layer 31. Each pixel opening exposes at least a portion of a first electrode 311. The light-emitting portion 331 in the light-emitting functional layer 33 is disposed within the pixel opening and is electrically connected to both the first electrode 311 and the second electrode 321.

[0114] By exposing at least a portion of a first electrode 311 through each pixel opening, the pixel definition layer (PDL) 4 can effectively define the actual effective area of ​​the first electrode 311 (i.e., the area where the first electrode 311 is directly electrically connected to the light-emitting part 331 in the light-emitting functional layer 33), thereby defining the light-emitting area and light-emitting area of ​​the sub-pixel F.

[0115] In some embodiments, referring to FIG2, the display panel 10 further includes an encapsulation structure 5. The encapsulation structure 5 is located on the side of the light-emitting device layer 3 away from the substrate 1. The encapsulation structure 5 is used to encapsulate the light-emitting device layer 3, thereby protecting the light-emitting device layer 3 from corrosion caused by external water and oxygen.

[0116] For example, please continue to refer to FIG2, the encapsulation structure 5 is located on the side of the cover plate 20 near the substrate 1, that is, the encapsulation structure 5 is located between the cover plate 20 and the light-emitting device layer 3.

[0117] For example, the encapsulation structure 5 may include an inorganic encapsulation layer and an organic encapsulation layer. The inorganic encapsulation layer is made of an inorganic material and can be used to block water and oxygen. The organic encapsulation layer is made of an organic material and can serve to flatten interfaces, cover defects, and relieve stress.

[0118] The structure of the sub-pixel F within the aforementioned display panel 10 will be described in detail below.

[0119] In some embodiments, as shown in Figures 4A and 4B, which are both film layer structure diagrams of sub-pixels F in a display panel 10 according to some embodiments, sub-pixels F include a first electrode 311 located in a first electrode layer 31, a light-emitting portion 331 located in a light-emitting functional layer 33, and a second electrode 321 located in a second electrode layer 32. The first electrode 311, the light-emitting portion 331, and the second electrode 321 are sequentially stacked along a third direction Z (i.e., the thickness direction of the display device 100). In some examples, the second electrodes 321 of multiple sub-pixels F can be interconnected to form a complete film layer structure.

[0120] For example, one of the first electrode 311 and the second electrode 321 can serve as the anode of the sub-pixel F, and the other can serve as the cathode of the sub-pixel F.

[0121] For example, the first electrode 311 can serve as the anode of the sub-pixel F. The first electrode 311 is configured to inject holes into the light-emitting portion 331. The second electrode 321 can serve as the cathode of the sub-pixel F. The second electrode 321 is configured to inject electrons into the light-emitting portion 331.

[0122] The following describes some embodiments of this disclosure using the first electrode 311 as the anode of sub-pixel F and the second electrode 321 as the cathode of sub-pixel F as an example.

[0123] For example, the material used to form the first electrode 311 may include metallic materials, such as any one or more of magnesium (Mg), silver (Ag), copper (Cu), aluminum (Al), titanium (Ti) and molybdenum (Mo).

[0124] The material used to form the first electrode 311 may also include alloys of the aforementioned metallic materials, such as aluminum-neodymium alloy (AlNd) or molybdenum-niobium alloy (MoNb).

[0125] For example, the first electrode 311 may be a single-layer structure.

[0126] Alternatively, the first electrode 311 can also be a multilayer composite structure. For example, the first electrode 311 can be a Ti / Al / Ti structure, etc. Another example is that the first electrode 311 can be a stacked structure formed of metallic materials and transparent conductive materials, such as ITO / Ag / ITO, Mo / AlNd / ITO, etc.

[0127] For example, the material used to form the second electrode 321 may include any one or more of magnesium (Mg), silver (Ag), aluminum (Al), etc.

[0128] The material used to form the second electrode 321 may also include alloys made of any one or more of magnesium (Mg), silver (Ag), aluminum (Al), etc.

[0129] The material used to form the second electrode 321 may also include a transparent conductive material, such as indium tin oxide (ITO).

[0130] In some embodiments, referring to Figures 4A and 4B, the light-emitting portion 331 within the sub-pixel F includes a light-emitting layer 6. Specifically, the phrase "the first electrode 311 is configured to inject holes into the light-emitting portion 331" can mean that the first electrode 311 is configured to inject holes into the light-emitting layer 6 within the light-emitting portion 331.

[0131] Specifically, the above-mentioned "the second electrode 321 is configured to inject electrons into the light-emitting part 331" can be that the second electrode 321 is configured to inject electrons into the light-emitting layer 6 within the light-emitting part 331.

[0132] For example, referring to Figure 4A, the display panel 10 can be an OLED display panel. Since the display panel 10 is an OLED display panel, the light-emitting layer 6 can include an organic light-emitting layer (EML). For example, the organic light-emitting layer EML can include a host material and a guest material, where the guest material can be a fluorescent dopant or a phosphorescent dopant.

[0133] Alternatively, referring to Figure 4B, the display panel 10 can also be a QLED display panel. Since the display panel 10 is a QLED display panel, the light-emitting layer 6 may include a quantum dot layer (QDL). For example, the quantum dot layer (QDL) may have quantum dot particles, which can be interconnected through surface-modified groups.

[0134] For example, the material of the luminescent layer 6 may include organic materials. Examples include toxoid compounds, perylene compounds, coumarin compounds, azacoumarin compounds, oxazole compounds, oxadiazole compounds, violacetone compounds, pyrrolopyrrole compounds, naphthalene compounds, anthracene compounds, fluorene compounds, fluoranthene compounds, tetraphenylene compounds, pyrene compounds, phenanthrene compounds, quinolone compounds and azaquinolone compounds, pyrazoline derivatives and pyrazolineone derivatives, rhodamine compounds, compounds, phenanthrene compounds, cyclopentadiene compounds, piracene compounds, diphenylquinone compounds, styryl compounds, butadiene compounds, dicyanomethylenepyran compounds, dicyanomethylenethiopyran compounds, fluorescein compounds, pyranonium compounds, thiaranonium compounds, selenonium compounds, telluronium compounds, aromatic aldehyde diene compounds, oligophenylene compounds, thioxanol compounds, anthocyanin compounds, acridine compounds, etc.

[0135] In some embodiments, please continue to refer to Figures 4A and 4B, the light-emitting part 331 in the sub-pixel F further includes one or more of the following: a hole injection layer (HIL), a hole transport layer (HTL), an electron block layer (EBL), a hole block layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL).

[0136] A hole injection layer (HIL) may be located between the light-emitting layer 6 and the first electrode 311. The hole injection layer (HIL) facilitates the injection of holes from the first electrode 311 into the light-emitting layer 6. Exemplarily, the hole injection layer (HIL) may be a coated film layer, for example, formed by coating and drying a solution using a hole injection material as a solute. The hole injection layer (HIL) may also be a vapor-deposited film layer, for example, formed by vapor deposition of conductive polymer materials such as PSS (a mixture of polythiophene and polystyrene sulfonic acid), polyfluorene, or its derivatives, or polyarylamines, or oxides of Ag, Mo, chromium (Cr), vanadium (V), tungsten (W), nickel (Ni), iridium (Ir), etc.

[0137] A hole transport layer (HTL) may be located between the light-emitting layer 6 and the first electrode 311. In the case where the light-emitting portion 331 within the sub-pixel F includes a hole injection layer (HIL), the hole transport layer (HTL) may be located between the hole injection layer (HIL) and the light-emitting layer 6. The hole transport layer (HTL) has the function of transporting holes injected from the hole injection layer (HIL) to the light-emitting layer 6. Exemplarily, the hole transport layer (HTL) may be a coated film layer, for example, formed by coating and drying a solution using a hole transport material as a solute. The hole transport layer (HTL) may also be a vapor-deposited film layer, for example, formed by vapor-depositing polymers such as polyfluorene, its derivatives, or polyarylamines, their derivatives.

[0138] An electron block layer (EBL) may be located between the light-emitting layer 6 and the first electrode 311. In the case where the light-emitting part 331 in the sub-pixel F includes a hole transport layer (HTL), the electron block layer (EBL) may be located between the hole transport layer (HTL) and the light-emitting layer 6.

[0139] An electron injection layer (EIL) may be located between the light-emitting layer 6 and the second electrode 321. The electron injection layer (EIL) has the function of injecting electrons supplied from the second electrode 321 into the light-emitting layer 6. Exemplarily, the electron injection layer (EIL) includes an organic material with high electron transport properties, and doped with an alkali metal, alkaline earth metal, or lanthanide element. For example, the organic material in the electron injection layer (EIL) may include π-electron-based low-molecular-weight organic materials such as oxadiazole derivatives (OXD), triazole derivatives (TAZ), and phenanthroline derivatives (BCP, Bphen). The dopant material in the electron injection layer (EIL) may include metal monomers, fluorides (e.g., NaF), quinoline complexes (e.g., Alq3, Liq), etc.

[0140] An electron transport layer (ETL) may be located between the light-emitting layer 6 and the second electrode 321. In the case where the light-emitting portion 331 within the sub-pixel F includes an electron injection layer (EIL), the ETL may be located between the EIL and the light-emitting layer 6. The ETL functions to transport electrons from the second electrode 321 to the light-emitting layer 6. The ETL is formed of an organic material with high electron transport properties. Exemplarily, the ETL comprises an organic material. For example, the ETL may include π-electron-based low-molecular-weight organic materials such as pyridine derivatives, pyrimidine derivatives, triazine derivatives, imidazole derivatives, oxadiazole derivatives, triazole derivatives, quinazoline derivatives, and phenanthroline derivatives.

[0141] A hole block layer (HBL) may be located between the light-emitting layer 6 and the second electrode 321. When the light-emitting portion 331 within the sub-pixel F includes an electron transport layer (ETL), the hole block layer (HBL) may be located between the electron transport layer (ETL) and the light-emitting layer 6. The hole block layer (HBL) has the function of restricting the outflow of holes from the light-emitting layer 6 to the hole block layer (HBL) and controlling the injection of electrons from the electron transport layer (ETL) to the light-emitting layer 6. Exemplarily, the material of the hole block layer (HBL) may include organic materials, such as pyridine derivatives, pyrimidine derivatives, triazine derivatives, imidazole derivatives, oxadiazole derivatives, triazole derivatives, quinazoline derivatives, phenanthroline derivatives, etc.

[0142] The following explains the light-emitting principle of the aforementioned sub-pixel F.

[0143] In some embodiments, as shown in FIG5, FIG5 is a film layer structure diagram of a sub-pixel F in a display panel 10 according to some embodiments. Based on a first electrode 311 serving as the anode of the sub-pixel F and a second electrode 321 serving as the cathode of the sub-pixel F, when a voltage is applied between the first electrode 311 and the second electrode 321, holes h injected from the first electrode 311 can be transported to the light-emitting layer 6, and electrons e injected from the second electrode 321 can also be transported to the light-emitting layer 6. Electrons e and holes h, as charge carriers, recombine in the light-emitting layer 6 to generate excitons J, which emit light when transitioning from the excited state to the ground state. The region where electrons e and holes h recombine can be called the recombination region (i.e., the light-emitting region) M.

[0144] In some embodiments, referring to FIG5, the light-emitting layer 6 is a second light-emitting layer 62. When the light-emitting layer 6 is the second light-emitting layer 62, the first electrode 311 is configured to inject holes into the second light-emitting layer 62, and the second electrode 321 is configured to inject electrons into the second light-emitting layer 62. The second light-emitting layer 62 is a single-layer structure.

[0145] In some embodiments, as shown in FIG6, FIG6 is a film structure diagram of a sub-pixel F in a display panel 10 according to some embodiments. The light-emitting layer 6 is a first light-emitting layer 61. When the light-emitting layer 6 is a first light-emitting layer 61, the first electrode 311 is configured to inject holes into the first light-emitting layer 61, and the second electrode 321 is configured to inject electrons into the first light-emitting layer 61.

[0146] The first light-emitting layer 61 includes at least two stacked light-emitting sublayers 611. The hole mobility of each light-emitting sublayer 611 in the first light-emitting layer 61 is less than the electron mobility of the light-emitting sublayer 611.

[0147] By making the first light-emitting layer 61 include at least two stacked light-emitting sub-layers 611, and the hole mobility of each light-emitting sub-layer 611 in the first light-emitting layer 61 is less than the electron mobility of the light-emitting sub-layer 611, that is, the electron mobility of each light-emitting sub-layer 611 in the first light-emitting layer 61 is larger and the hole mobility is smaller, it is convenient for the electrons e injected by the second electrode 321 to be transported to the light-emitting sub-layers 611 in the first light-emitting layer 61 that are relatively close to the first electrode 311, and it can avoid excessive transmission of holes h injected by the first electrode 311 to the light-emitting sub-layers 611 in the first light-emitting layer 61 that are relatively far away from the first electrode 311. This is beneficial for holes h and electrons e to be relatively close to the first electrode 311 in the first light-emitting layer 61. The recombination in the light-emitting sublayer 611 of the first light-emitting layer 61 allows most or all of the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 to be located in the light-emitting sublayer 611 relatively close to the first electrode 311. This reduces the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61, making the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 smaller than the recombination region (i.e., the light-emitting region) M of the monolayer structure of the second light-emitting layer 62 in the embodiment shown in FIG. 5. This facilitates the recombination of electrons e and holes h, which are charge carriers, in the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61, and is beneficial to improving the recombination efficiency of electrons e and holes h in the first light-emitting layer 61.

[0148] It should be noted that Figure 6 is only illustrated with the example of three layers of light-emitting sub-layers 611 stacked inside the first light-emitting layer 61. The number of light-emitting sub-layers 611 stacked inside the first light-emitting layer 61 is not limited to this. For example, the number of light-emitting sub-layers 611 stacked inside the first light-emitting layer 61 can also be two, four, five or six layers, etc.

[0149] In the case where the multiple sub-pixels F in the display panel 10 include a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3, and the first color sub-pixel F1 is a red sub-pixel, the second color sub-pixel F2 is a green sub-pixel, and the third color sub-pixel F3 is a blue sub-pixel, as shown in Figures 7A, 7B, and 7C, Figure 7A is a curve showing the relationship between voltage and current density of the first color sub-pixel (i.e., the red sub-pixel) F1 in the display panel 10, Figure 7B is a curve showing the relationship between voltage and current density of the second color sub-pixel (i.e., the green sub-pixel) F2 in the display panel 10, and Figure 7C is a curve showing the relationship between voltage and current density of the third color sub-pixel (i.e., the blue sub-pixel) F3 in the display panel 10.

[0150] Please refer to Figure 7A. In Figure 7A, the horizontal axis represents the operating voltage of the first color sub-pixel (i.e., the red sub-pixel) F1, and the vertical axis represents the current density of the first color sub-pixel (i.e., the red sub-pixel) F1. Curve S1 shows the relationship between the operating voltage and current density of the first color sub-pixel F1, including the first emitting layer 61, and curve S2 shows the relationship between the operating voltage and current density of the first color sub-pixel F1, including the second emitting layer 62.

[0151] When the first color sub-pixel F1 requires the same current density, the operating voltage of the first color sub-pixel F1 including the first light-emitting layer 61 is less than the operating voltage of the first color sub-pixel F1 including the second light-emitting layer 62. In other words, the operating voltage of the first color sub-pixel F1 including the first light-emitting layer 61 is smaller than that of the first color sub-pixel F1 including the second light-emitting layer 62. Therefore, when the first color sub-pixel F1 in the display panel 10 is the first color sub-pixel F1 including the first light-emitting layer 61, the bias voltage required by the display panel 10 can be reduced.

[0152] Please refer to Figure 7B. In Figure 7B, the horizontal axis represents the operating voltage of the second color sub-pixel (i.e., the green sub-pixel) F2, and the vertical axis represents the current density of the second color sub-pixel (i.e., the green sub-pixel) F2. Curve S3 shows the relationship between the operating voltage and current density of the second color sub-pixel F2, including the first emitting layer 61, and curve S4 shows the relationship between the operating voltage and current density of the second color sub-pixel F2, including the second emitting layer 62.

[0153] When the second color sub-pixel F2 requires the same current density, the operating voltage of the second color sub-pixel F2 including the first light-emitting layer 61 is lower than that of the second color sub-pixel F2 including the second light-emitting layer 62. In other words, the operating voltage of the second color sub-pixel F2 including the first light-emitting layer 61 is smaller than that of the second color sub-pixel F2 including the second light-emitting layer 62. Therefore, when the second color sub-pixel F2 in the display panel 10 is the second color sub-pixel F2 including the first light-emitting layer 61, the bias voltage required by the display panel 10 can be reduced.

[0154] Please refer to Figure 7C. In Figure 7C, the horizontal axis represents the operating voltage of the third color sub-pixel (i.e., the blue sub-pixel) F3, and the vertical axis represents the current density of the third color sub-pixel (i.e., the blue sub-pixel) F3. Curve S5 shows the relationship between the operating voltage and current density of the third color sub-pixel F3, which includes the first emitting layer 61, and curve S6 shows the relationship between the operating voltage and current density of the third color sub-pixel F3, which includes the second emitting layer 62.

[0155] When the third color sub-pixel F3 requires the same current density, the operating voltage of the third color sub-pixel F3 including the first light-emitting layer 61 is lower than that of the third color sub-pixel F3 including the second light-emitting layer 62. In other words, the operating voltage of the third color sub-pixel F3 including the first light-emitting layer 61 is smaller than that of the third color sub-pixel F3 including the second light-emitting layer 62. Therefore, when the third color sub-pixel F3 in the display panel 10 is the third color sub-pixel F3 including the first light-emitting layer 61, the bias voltage required by the display panel 10 can be reduced.

[0156] As shown in Figures 8A, 8B, and 8C, Figure 8A is a curve showing the relationship between the brightness and efficiency of the first color sub-pixel (i.e., the red sub-pixel) F1 in the display panel 10, Figure 8B is a curve showing the relationship between the brightness and efficiency of the second color sub-pixel (i.e., the green sub-pixel) F2 in the display panel 10, and Figure 8C is a curve showing the relationship between the brightness and efficiency of the third color sub-pixel (i.e., the blue sub-pixel) F3 in the display panel 10.

[0157] Please refer to Figure 8A. In Figure 8A, the horizontal axis represents the luminance of the first color sub-pixel (i.e., the red sub-pixel) F1, and the vertical axis represents the current efficiency of the first color sub-pixel (i.e., the red sub-pixel) F1. Curve S7 shows the relationship between the luminance and current efficiency of the first color sub-pixel F1, including the first emitting layer 61, and curve S8 shows the relationship between the luminance and current efficiency of the first color sub-pixel F1, including the second emitting layer 62.

[0158] When the luminance of the first color sub-pixel F1 is the same, the current efficiency of the first color sub-pixel F1 including the first light-emitting layer 61 is greater than that of the first color sub-pixel F1 including the second light-emitting layer 62. In other words, the current efficiency of the first color sub-pixel F1 including the first light-emitting layer 61 is higher than that of the first color sub-pixel F1 including the second light-emitting layer 62. Therefore, when the first color sub-pixel F1 in the display panel 10 is the first color sub-pixel F1 including the first light-emitting layer 61, the luminous efficiency and performance of the display panel 10 can be improved.

[0159] Please refer to Figure 8B. In Figure 8B, the horizontal axis represents the luminance of the second color sub-pixel (i.e., the green sub-pixel) F2, and the vertical axis represents the current efficiency of the second color sub-pixel (i.e., the green sub-pixel) F2. Curve S9 shows the relationship between the luminance and current efficiency of the second color sub-pixel F2, which includes the first emitting layer 61, and curve S10 shows the relationship between the luminance and current efficiency of the second color sub-pixel F2, which includes the second emitting layer 62.

[0160] When the luminance of the second color sub-pixel F2 is the same, the current efficiency of the second color sub-pixel F2 including the first light-emitting layer 61 is greater than that of the second color sub-pixel F2 including the second light-emitting layer 62. In other words, the current efficiency of the second color sub-pixel F2 including the first light-emitting layer 61 is higher than that of the second color sub-pixel F2 including the second light-emitting layer 62. Therefore, when the second color sub-pixel F2 in the display panel 10 is the second color sub-pixel F2 including the first light-emitting layer 61, the luminous efficiency and performance of the display panel 10 can be improved.

[0161] Please refer to Figure 8C. In Figure 8C, the horizontal axis represents the luminance of the third color sub-pixel (i.e., the blue sub-pixel) F3, and the vertical axis represents the current efficiency of the third color sub-pixel (i.e., the blue sub-pixel) F3. Curve S11 shows the relationship between the luminance and current efficiency of the third color sub-pixel F3, which includes the first emitting layer 61, and curve S12 shows the relationship between the luminance and current efficiency of the third color sub-pixel F3, which includes the second emitting layer 62.

[0162] When the luminance of the third color sub-pixel F3 is the same, the current efficiency of the third color sub-pixel F3 including the first light-emitting layer 61 is greater than that of the third color sub-pixel F3 including the second light-emitting layer 62. In other words, the current efficiency of the third color sub-pixel F3 including the first light-emitting layer 61 is higher than that of the third color sub-pixel F3 including the second light-emitting layer 62. Therefore, when the third color sub-pixel F3 in the display panel 10 is the third color sub-pixel F3 including the first light-emitting layer 61, the luminous efficiency and performance of the display panel 10 can be improved.

[0163] In summary, when the sub-pixel F in the display panel 10 includes a first light-emitting layer 61 (e.g., a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3), compared to the sub-pixel F in the display panel 10 including a second light-emitting layer 62 (e.g., a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3), the bias voltage required by the display panel 10 can be reduced, and the luminous efficiency and performance of the display panel 10 can be improved.

[0164] For example, the first light-emitting layer 61 includes an organic light-emitting layer (EML). The light-emitting layer guest materials (e.g., fluorescent dopants or phosphorescent dopants) contained in at least two light-emitting sublayers 611 within the first light-emitting layer 61 may be the same or different.

[0165] For example, the ratio of electron mobility to hole mobility in each light-emitting sublayer 611 within the first light-emitting layer 61 is greater than or equal to 10.

[0166] By ensuring that the ratio of electron mobility to hole mobility in each light-emitting sublayer 611 within the first light-emitting layer 61 is greater than or equal to 10 (i.e., the electron mobility of each light-emitting sublayer 611 within the first light-emitting layer 61 is much greater than the hole mobility), it is easier for electrons injected by the second electrode 321 to transport to the light-emitting sublayers 611 within the first light-emitting layer 61 that are relatively close to the first electrode 311. Furthermore, it can largely prevent excessive hole transport by the holes injected by the first electrode 311 to the light-emitting sublayers 611 that are relatively far from the first electrode 311. Furthermore, by making most or all of the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 located in the light-emitting sub-layer 611 relatively close to the first electrode 311 within the first light-emitting layer 61, the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 is further reduced, thereby further improving the recombination efficiency of electrons and holes in the light-emitting sub-layer 611 relatively close to the first electrode 311 (injected holes) within the first light-emitting layer 61. This can further reduce the bias voltage required by the display panel 10 and further improve the luminous efficiency and performance of the display panel 10.

[0167] The following describes how the electron mobility of at least two light-emitting sub-layers 611 in the first light-emitting layer 61 is set.

[0168] In some embodiments, as shown in FIG9, FIG9 is a film layer structure diagram of a sub-pixel F in a display panel 10 according to some embodiments. The first light-emitting layer 61 includes a first light-emitting sub-layer 611a and a second light-emitting sub-layer 611b adjacent to the first light-emitting sub-layer 611a, wherein the first light-emitting sub-layer 611a is closer to the first electrode 311 than the second light-emitting sub-layer 611b. The electron mobility of the second light-emitting sub-layer 611b is greater than that of the first light-emitting sub-layer 611a.

[0169] It is understood that Figure 9 shows the case where the first light-emitting layer 61 includes two light-emitting sub-layers 611. In other embodiments, the first light-emitting layer 61 may include three or more light-emitting sub-layers 611. Among these light-emitting sub-layers 611, the first light-emitting sub-layer 611a and the second light-emitting sub-layer 611b are closer to the first electrode 311 than the other light-emitting sub-layers 611.

[0170] By making the first light-emitting layer 61 include a first light-emitting sublayer 611a and a second light-emitting sublayer 611b adjacent to the first light-emitting sublayer 611a, the first light-emitting sublayer 611a is closer to the first electrode 311 than the second light-emitting sublayer 611b, and the electron mobility of the second light-emitting sublayer 611b in the first light-emitting layer 61 is greater than the electron mobility of the first light-emitting sublayer 611a in the first light-emitting layer 61, the injection barrier for electrons to transfer from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a can be increased, avoiding the excessively rapid transfer of electrons from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a. This is beneficial for protecting the electron block layer (EBL) located on the side of the first light-emitting sublayer 611a away from the second light-emitting sublayer 611b, preventing the electron block layer (EBL) from failing, and thus improving the service life of the display panel 10.

[0171] In the case where multiple sub-pixels F within the display panel 10 include a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3, and the first color sub-pixel F1 is a red sub-pixel, the second color sub-pixel F2 is a green sub-pixel, and the third color sub-pixel F3 is a blue sub-pixel, as shown in Figures 10A, 10B, and 10C, Figure 10A is a curve showing the relationship between the usage time and brightness of the first color sub-pixel (i.e., the red sub-pixel) F1 within the display panel 10, Figure 10B is a curve showing the relationship between the usage time and brightness of the second color sub-pixel (i.e., the green sub-pixel) F2 within the display panel 10, and Figure 10C is a curve showing the relationship between the usage time and brightness of the third color sub-pixel (i.e., the blue sub-pixel) F3 within the display panel 10.

[0172] Please refer to Figure 10A. In Figure 10A, the horizontal axis represents the usage time (Hour Pass) of the first color sub-pixel (i.e., the red sub-pixel) F1, and the vertical axis represents the brightness (Luminance) of the first color sub-pixel (i.e., the red sub-pixel) F1. Curve S13 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the first color sub-pixel F1, which includes the first emitting layer 61 and in which the electron mobility of the second emitting sub-layer 611b within the first emitting layer 61 is greater than that of the first emitting sub-layer 611a within the first emitting layer 61. Curve S14 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the first color sub-pixel F1, which includes the second emitting layer 62.

[0173] When the luminance of the first color sub-pixel F1 is the same, the hour pass of the first color sub-pixel F1 including the first light-emitting layer 61 is greater than that of the first color sub-pixel F1 including the second light-emitting layer 62. In other words, the lifespan of the first color sub-pixel F1 including the first light-emitting layer 61 is longer than that of the first color sub-pixel F1 including the second light-emitting layer 62. Therefore, when the first color sub-pixel F1 in the display panel 10 includes the first light-emitting layer 61, and the electron mobility of the second light-emitting sublayer 611b in the first light-emitting layer 61 is greater than that of the first light-emitting sublayer 611a in the first light-emitting layer 61, the lifespan of the display panel 10 can be extended.

[0174] Please refer to Figure 10B. In Figure 10B, the horizontal axis represents the usage time (Hour Pass) of the second color sub-pixel (i.e., the green sub-pixel) F2, and the vertical axis represents the brightness (Luminance) of the second color sub-pixel (i.e., the green sub-pixel) F2. Curve S15 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the second color sub-pixel F2, which includes the first emitting layer 61 and whose electron mobility is greater than that of the first emitting sub-layer 611a within the first emitting layer 61. Curve S16 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the second color sub-pixel F2, which includes the second emitting layer 62.

[0175] When the luminance of the second color sub-pixel F2 is the same, the hour pass of the second color sub-pixel F2 including the first light-emitting layer 61 is greater than that of the second color sub-pixel F2 including the second light-emitting layer 62. In other words, the second color sub-pixel F2 including the first light-emitting layer 61 has a longer lifespan than the second color sub-pixel F2 including the second light-emitting layer 62. Therefore, when the second color sub-pixel F2 in the display panel 10 includes the first light-emitting layer 61, and the electron mobility of the second light-emitting sublayer 611b within the first light-emitting layer 61 is greater than the electron mobility of the first light-emitting sublayer 611a within the first light-emitting layer 61, the lifespan of the display panel 10 can be extended.

[0176] Please refer to Figure 10C. In Figure 10C, the horizontal axis represents the usage time (Hour Pass) of the third color sub-pixel (i.e., the blue sub-pixel) F3, and the vertical axis represents the brightness (Luminance) of the third color sub-pixel (i.e., the blue sub-pixel) F3. Curve S17 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the third color sub-pixel F3, which includes the first emitting layer 61 and in which the electron mobility of the second emitting sub-layer 611b within the first emitting layer 61 is greater than that of the first emitting sub-layer 611a within the first emitting layer 61. Curve S18 shows the relationship between the usage time (Hour Pass) and brightness (Luminance) of the third color sub-pixel F3, which includes the second emitting layer 62.

[0177] When the luminance of the third color sub-pixel F3 is the same, the hour pass of the third color sub-pixel F3 including the first light-emitting layer 61 is greater than that of the third color sub-pixel F3 including the second light-emitting layer 62. In other words, the lifespan of the third color sub-pixel F3 including the first light-emitting layer 61 is longer than that of the third color sub-pixel F3 including the second light-emitting layer 62. Therefore, when the third color sub-pixel F3 in the display panel 10 includes the first light-emitting layer 61, and the electron mobility of the second light-emitting sublayer 611b in the first light-emitting layer 61 is greater than that of the first light-emitting sublayer 611a in the first light-emitting layer 61, the lifespan of the display panel 10 can be extended.

[0178] In some embodiments, as shown in FIG11, FIG11 is a film structure diagram of a sub-pixel F in a display panel 10 according to some embodiments. The first light-emitting layer 61 includes at least three light-emitting sub-layers 611, and the electron mobility of the at least three light-emitting sub-layers 611 in the first light-emitting layer 61 increases sequentially along the direction from the first electrode 311 to the second electrode 321.

[0179] For example, please continue to refer to FIG11, the first light-emitting layer 61 may include three light-emitting sub-layers 611.

[0180] Alternatively, the first light-emitting layer 61 may also include four light-emitting sublayers 611.

[0181] Alternatively, the first light-emitting layer 61 may also include five light-emitting sub-layers 611.

[0182] Alternatively, the first light-emitting layer 61 may also include six light-emitting sublayers 611.

[0183] Taking the first light-emitting layer 61 as an example, which may include three light-emitting sub-layers 611, please continue to refer to Figure 11. The first light-emitting layer 61 includes a first light-emitting sub-layer 611a, a second light-emitting sub-layer 611b, and a third light-emitting sub-layer 611c. Along the direction from the first electrode 311 to the second electrode 321, the first light-emitting sub-layer 611a, the second light-emitting sub-layer 611b, and the third light-emitting sub-layer 611c are stacked sequentially, that is, the first light-emitting sub-layer 611a is closer to the first electrode 311 than the third light-emitting sub-layer 611c, and the second light-emitting sub-layer 611b is located between the first light-emitting sub-layer 611a and the second light-emitting sub-layer 611b.

[0184] Since the first light-emitting layer 61 comprises three light-emitting sublayers 611 (i.e., the first light-emitting sublayer 611a, the second light-emitting sublayer 611b, and the third light-emitting sublayer 611c), the aforementioned "the electron mobility of at least three light-emitting sublayers 611 in the first light-emitting layer 61 increases sequentially along the direction from the first electrode 311 to the second electrode 321" means that the electron mobility of the first light-emitting sublayer 611a, the second light-emitting sublayer 611b, and the third light-emitting sublayer 611c increases sequentially. That is, the electron mobility of the first light-emitting sublayer 611a is less than that of both the second and third light-emitting sublayers 611b, and the electron mobility of the second light-emitting sublayer 611b is less than that of the third light-emitting sublayer 611c.

[0185] By sequentially increasing the electron mobility of the first light-emitting sublayer 611a, the second light-emitting sublayer 611b, and the third light-emitting sublayer 611c, when electrons travel from the third light-emitting sublayer 611c through the second light-emitting sublayer 611b to the first light-emitting sublayer 611a, the injection barrier for electrons to travel from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a is increased, preventing electrons from traveling too quickly from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a. Similarly, the injection barrier for electrons to travel from the third light-emitting sublayer 611c to the second light-emitting sublayer 611b is also increased, preventing electrons from traveling too quickly from the third light-emitting sublayer 611c to the second light-emitting sublayer 611b. This further protects the electron block layer (EBL) located on the side of the first light-emitting sublayer 611a away from the second light-emitting sublayer 611b, preventing EBL failure and further improving the lifespan of the display panel 10.

[0186] The following describes how the hole mobility of at least two light-emitting sub-layers 611 in the first light-emitting layer 61 is set.

[0187] In some embodiments, referring to FIG9, the first light-emitting layer 61 includes a first light-emitting sublayer 611a and a second light-emitting sublayer 611b adjacent to the first light-emitting sublayer 611a. The first light-emitting sublayer 611a is closer to the first electrode 311 than the second light-emitting sublayer 611b. The hole mobility of the second light-emitting sublayer 611b is greater than or equal to the hole mobility of the first light-emitting sublayer 611a. That is, the hole mobility of the first light-emitting sublayer 611a is the same as the hole mobility of the second light-emitting sublayer 611b, or the hole mobility of the first light-emitting sublayer 611a is smaller than the hole mobility of the second light-emitting sublayer 611b.

[0188] When the hole mobility of the first light-emitting sublayer 611a and the hole mobility of the second light-emitting sublayer 611b are the same, since the hole mobility of each light-emitting sublayer 611 in the first light-emitting layer 61 is less than the electron mobility of the light-emitting sublayer 611, that is, the hole mobility of the first light-emitting sublayer 611a is less than the electron mobility of the first light-emitting sublayer 611a, and the hole mobility of the second light-emitting sublayer 611b is less than the electron mobility of the second light-emitting sublayer 611b. In other words, electrons travel faster in the first light-emitting sublayer 611a and the second light-emitting sublayer 611b, while holes travel slower. Therefore, even if the hole mobility of the first light-emitting sublayer 611a and the second light-emitting sublayer 611b is the same, it can prevent too many holes injected by the first electrode 311 from being transported to other light-emitting sublayers 611 within the first light-emitting layer 61 besides the first light-emitting sublayer 611a. This is beneficial for the recombination of holes and electrons in the first light-emitting sublayer 611a within the first light-emitting layer 61, thereby improving the recombination efficiency of electrons and holes in the first light-emitting layer 61.

[0189] When the hole mobility of the first light-emitting sublayer 611a is smaller than that of the second light-emitting sublayer 611b, the holes travel more slowly in the first light-emitting sublayer 611a and relatively faster in the second light-emitting sublayer 611b. This can further prevent too many holes injected by the first electrode 311 from traveling to other light-emitting sublayers 611 (e.g., the second light-emitting sublayer 611b) within the first light-emitting layer 61. This is beneficial for the recombination of holes and electrons in the first light-emitting sublayer 611a within the first light-emitting layer 61, and further improves the recombination efficiency of electrons and holes in the first light-emitting layer 61.

[0190] In some embodiments, please continue to refer to FIG11, based on the first light-emitting layer 61 including at least three light-emitting sub-layers 611 (e.g., first light-emitting sub-layer 611a, second light-emitting sub-layer 611b and third light-emitting sub-layer 611c, etc.), the hole mobility of the at least three light-emitting sub-layers 611 increases sequentially along the direction from the first electrode 311 to the second electrode 321.

[0191] Taking the first light-emitting layer 61 as potentially comprising three light-emitting sub-layers 611 as an example, the aforementioned statement that "the hole mobility of at least three light-emitting sub-layers 611 in the first light-emitting layer 61 increases sequentially along the direction from the first electrode 311 to the second electrode 321" means that the hole mobility of the first light-emitting sub-layer 611a, the second light-emitting sub-layer 611b, and the third light-emitting sub-layer 611c increases sequentially. That is, the hole mobility of the first light-emitting sub-layer 611a is less than both the hole mobility of the second light-emitting sub-layer 611b and the third light-emitting sub-layer 611c, and the hole mobility of the second light-emitting sub-layer 611b is less than the hole mobility of the third light-emitting sub-layer 611c.

[0192] By increasing the hole mobility of the first light-emitting sublayer 611a, the second light-emitting sublayer 611b, and the third light-emitting sublayer 611c sequentially, the hole transport rate in the first light-emitting sublayer 611a, the second light-emitting sublayer 611b, and the third light-emitting sublayer 611c sequentially decreases. This further prevents excessive holes injected by the first electrode 311 from being transported to other light-emitting sublayers 611 (e.g., the second light-emitting sublayer 611b and the third light-emitting sublayer 611c) within the first light-emitting layer 61. This is beneficial for the recombination of holes and electrons in the first light-emitting sublayer 611a within the first light-emitting layer 61, and further improves the recombination efficiency of electrons and holes in the first light-emitting layer 61.

[0193] The following describes how the thickness of at least two light-emitting sub-layers 611 in the first light-emitting layer 61 is set.

[0194] In some embodiments, please continue referring to FIG9, the first light-emitting layer 61 includes a first light-emitting sublayer 611a and a second light-emitting sublayer 611b adjacent to the first light-emitting sublayer 611a. The first light-emitting sublayer 611a is closer to the first electrode 311 than the second light-emitting sublayer 611b. The thickness h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61 is less than the thickness h2 of the second light-emitting sublayer 611b within the first light-emitting layer 61.

[0195] For example, the thickness h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61 can be 5nm to 10nm.

[0196] For example, the thickness h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61 can be 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, 9nm, 9.5nm, or 10nm, etc.

[0197] It should be noted that the aforementioned "thickness h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61" refers to the dimension h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61 along the third direction (i.e., the thickness direction of the display device 100) Z. Similarly, the aforementioned "thickness h2 of the second light-emitting sublayer 611b within the first light-emitting layer 61" refers to the dimension h2 of the second light-emitting sublayer 611b within the first light-emitting layer 61 along the third direction (i.e., the thickness direction of the display device 100) Z. The following descriptions of "thickness h1 of the first light-emitting sublayer 611a within the first light-emitting layer 61" and "thickness h2 of the second light-emitting sublayer 611b within the first light-emitting layer 61" will follow this explanation and will not be repeated.

[0198] The following describes the setting method of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels of the film layer in the sub-pixel F of the display panel 10.

[0199] It should be noted that the lowest unoccupied molecular orbital (LUMO) level represents the orbital with the lowest energy level that does not have an electron, and it has a high affinity for electrons. The highest occupied molecular orbital (HOMO) level represents the orbital with the highest energy level that has an electron. Since the HOMO level already contains an electron, the higher the HOMO level, the higher its electron ionization potential, which is more favorable for receiving injected holes.

[0200] In the following text, the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) levels of the film layer in sub-pixel F refer to the energy levels of the organic materials forming the film layer. When the film layer in sub-pixel F includes multiple organic materials, the energy level of the representative organic material responsible for the transport of electrons or holes in the film layer is described as the lowest unoccupied molecular orbital (LUMO) or highest occupied molecular orbital (HOMO) level of the film layer.

[0201] In some embodiments, as shown in FIG12, FIG12 is a schematic diagram of the lowest unoccupied molecular orbital (LUMO) level and the highest occupied molecular orbital (HOMO) level of the film layer in the sub-pixel F of the display panel 10 according to some embodiments.

[0202] It should be noted that Figure 12 only shows the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels of the hole transport layer (HTL), electron block layer (EBL), first light-emitting layer 6 (e.g., the first light-emitting sublayer 611a and the second light-emitting sublayer 611b within the first light-emitting layer 6), hole block layer (HBL), and electron transport layer (ETL) in sub-pixel F, omitting other film layers in sub-pixel F.

[0203] Furthermore, Figure 12 shows the vacuum energy levels of electrons. The greater the difference between the lowest unoccupied molecular orbital (LUMO) level or the highest occupied molecular orbital (HOMO) level and the electron's vacuum energy level, the lower the LUMO level or the HOMO level.

[0204] The first light-emitting layer 61 includes a first light-emitting sublayer 611a and a second light-emitting sublayer 611b adjacent to the first light-emitting sublayer 611a. The first light-emitting sublayer 611a is closer to the first electrode 311 than the second light-emitting sublayer 611b. The absolute value of the highest occupied molecular orbital (HOMO) energy level of the first light-emitting sublayer 611a of the first light-emitting layer 61 is less than or equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the second light-emitting sublayer 611b of the first light-emitting layer 61.

[0205] In other words, the highest occupied molecular orbital (HOMO) energy level of the first luminescent sublayer 611a of the first luminescent layer 61 is higher than or equal to the highest occupied molecular orbital (HOMO) energy level of the second luminescent sublayer 611b of the first luminescent layer 61.

[0206] It should be noted that Figure 12 only shows the case where the absolute value of the highest occupied molecular orbital (HOMO) energy level of the first luminescent sublayer 611a is less than the absolute value of the highest occupied molecular orbital (HOMO) energy level of the second luminescent sublayer 611b. However, the embodiments of this disclosure include, but are not limited to, the absolute value of the highest occupied molecular orbital (HOMO) energy level of the first luminescent sublayer 611a can also be equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the second luminescent sublayer 611b.

[0207] Understandably, holes readily transition from a film layer with a lower Highest Occupied Molecular Orbital (HOMO) energy level to a film layer with a higher HOMO energy level, and conversely, holes find it difficult to transition from a film layer with a higher HOMO energy level to a film layer with a lower HOMO energy level. This is achieved by making the HOMO energy level of the first luminescent sublayer 611a of the first luminescent layer 61 higher than or equal to the HOMO energy level of the second luminescent sublayer 611b of the first luminescent layer 61. Orbital (HOMO) energy levels, when sub-pixel F is subjected to an external electric field, holes are less likely to jump from the first light-emitting sub-layer 611a to the second light-emitting sub-layer 611b. This can prevent excessive holes injected by the first electrode 311 from being transported to the second light-emitting sub-layer 611b, which is conducive to the recombination of holes and electrons in the first light-emitting sub-layer 611a. This allows most or all of the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 to be located in the first light-emitting sub-layer 611a, thereby reducing the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61. Making the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 smaller facilitates the recombination of electrons and holes as charge carriers in the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61. This is beneficial to improving the recombination efficiency of electrons e and holes h in the first light-emitting layer 61, thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0208] In some embodiments, please continue to refer to Figure 12, where the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL) is greater than or equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the first photonic layer 611a.

[0209] In other words, the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL) is lower than or equal to the highest occupied molecular orbital (HOMO) energy level of the first photonic layer 611a.

[0210] It should be noted that Figure 12 only shows the case where the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL) is greater than the absolute value of the highest occupied molecular orbital (HOMO) energy level of the first photonic layer 611a. However, the embodiments of this disclosure include, but are not limited to, the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL) can also be equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the first photonic layer 611a.

[0211] Holes can easily transition from a film layer with a lower highest occupied molecular orbital (HOMO) level to a film layer with a higher HOMO level, while conversely, holes find it difficult to transition from a film layer with a higher HOMO level to a film layer with a lower HOMO level. By setting the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL) to be lower than or equal to the highest occupied molecular orbital (HOMO) energy level of the first luminescent sublayer 611a, when the sub-pixel F is subjected to an external electric field, holes can relatively easily jump from the electron block layer (EBL) to the first luminescent sublayer 611a. This facilitates the recombination of electrons and holes, which act as charge carriers, in the first luminescent sublayer 611a, thereby improving the recombination efficiency of electrons and holes in the first luminescent sublayer 611a.

[0212] In some embodiments, please continue to refer to Figure 12, where the absolute value of the highest occupied molecular orbital (HOMO) energy level of the hole transport layer (HTL) is less than or equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL).

[0213] In other words, the highest occupied molecular orbital (HOMO) level of the hole transport layer (HTL) is higher than or equal to the highest occupied molecular orbital (HOMO) level of the electron block layer (EBL).

[0214] It should be noted that Figure 12 only shows the absolute value of the highest occupied molecular orbital (HOMO) energy level of the hole transport layer (HTL), which is less than or equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL). However, the embodiments of this disclosure include, but are not limited to, the absolute value of the highest occupied molecular orbital (HOMO) energy level of the hole transport layer (HTL) can also be equal to the absolute value of the highest occupied molecular orbital (HOMO) energy level of the electron block layer (EBL).

[0215] Holes can easily transition from a film layer with a lower highest occupied molecular orbital (HOMO) level to a film layer with a higher HOMO level, while conversely, holes find it difficult to transition from a film layer with a higher HOMO level to a film layer with a lower HOMO level. By setting the highest occupied molecular orbital (HOMO) level of the hole transport layer (HTL) to be higher than or equal to the highest occupied molecular orbital (HOMO) level of the electron block layer (EBL), when the sub-pixel F is subjected to an external electric field, holes are less likely to jump from the hole transport layer (HTL) to the electron block layer (EBL). This allows holes to accumulate at the interface between the hole transport layer (HTL) and the electron block layer (EBL), preventing holes in the hole transport layer (HTL) from passing too quickly through the electron block layer (EBL) into the first light-emitting layer 61. This also allows electrons and holes, acting as charge carriers, to approach the electron block layer (EBL) in the first light-emitting layer 61. The recombination at the interface of the first light-emitting sublayer 611a and the electron block layer (EBL) is achieved, thereby making the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 entirely or nearly entirely located in the first light-emitting sublayer 611a. This reduces the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61, making the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 smaller. This facilitates the recombination of electrons and holes, which are charge carriers, in the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61, which is beneficial to further improve the recombination efficiency of electrons and holes in the first light-emitting layer 61. This further reduces the bias voltage required by the display panel 10 and improves the luminous efficiency and performance of the display panel 10.

[0216] In some embodiments, please continue to refer to FIG12, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the first luminescent sublayer 611a of the first luminescent layer 61 is less than or equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second luminescent sublayer 611b of the first luminescent layer 61.

[0217] In other words, the lowest unoccupied molecular orbital (LUMO) energy level of the first luminescent sublayer 611a of the first luminescent layer 61 is higher than or equal to the lowest unoccupied molecular orbital (LUMO) energy level of the second luminescent sublayer 611b of the first luminescent layer 61.

[0218] It should be noted that Figure 12 only shows the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the first luminescent sublayer 611a, which is less than or equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second luminescent sublayer 611b. However, the embodiments of this disclosure include, but are not limited to, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the first luminescent sublayer 611a, which may also be equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second luminescent sublayer 611b.

[0219] Understandably, according to the principle of minimum energy (i.e., without violating the Pauli principle and Hund's rule, electrons preferentially occupy atomic orbitals with lower energy levels, so that the energy of the entire atomic system is at its lowest), electrons can easily jump from a film layer with a higher energy level of the lowest unoccupied molecular orbital (LUMO) to a film layer with a lower energy level of the same LUMO. Conversely, it is difficult for electrons to jump from a film layer with a lower energy level of the LUMO to a film layer with a higher energy level of the same LUMO. By making the lowest unoccupied molecular orbital (LUMO) energy level of the first light-emitting sublayer 611a of the first light-emitting layer 61 higher than or equal to the lowest unoccupied molecular orbital (LUMO) energy level of the second light-emitting sublayer 611b of the first light-emitting layer 61, when the sub-pixel F is subjected to an external electric field, electrons are less likely to jump from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a. This avoids electrons being transferred too quickly from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a, which helps protect the electron block layer (EBL) located on the side of the first light-emitting sublayer 611a away from the second light-emitting sublayer 611b, preventing the electron block layer (EBL) from failing, and thus improving the lifespan of the display panel 10.

[0220] In some embodiments, please continue to refer to Figure 12, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the Hole Block Layer (HBL) is greater than or equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second photonic layer 611b.

[0221] In other words, the lowest unoccupied molecular orbital (LUMO) level of the hole block layer (HBL) is lower than or equal to the lowest unoccupied molecular orbital (LUMO) level of the second photonic layer 611b.

[0222] It should be noted that Figure 12 only shows the case where the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the Hole Block Layer (HBL) is greater than the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second photonic layer 611b. However, the embodiments of this disclosure include, but are not limited to, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the Hole Block Layer (HBL) can also be equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second photonic layer 611b.

[0223] Electrons can easily transition from layers with higher Lowest Unoccupied Molecular Orbital (LUMO) energy levels to layers with lower LUMO energy levels, while electrons find it difficult to transition from layers with lower LUMO energy levels to layers with higher LUMO energy levels. By making the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL) lower than or equal to the lowest unoccupied molecular orbital (LUMO) energy level of the second light-emitting sublayer 611b, when the sub-pixel F is subjected to an external electric field, electrons are less likely to jump from the hole block layer (HBL) to the second light-emitting sublayer 611b. This prevents electrons from jumping too quickly from the hole block layer (HBL) to the second light-emitting sublayer 611b, and consequently prevents electrons from jumping too quickly from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a. This helps protect the electron block layer (EBL) located on the side of the first light-emitting sublayer 611a away from the second light-emitting sublayer 611b, preventing the electron block layer (EBL) from failing and thus improving the lifespan of the display panel 10.

[0224] For example, referring to Figure 12, the difference n1 between the absolute value of the lowest unoccupied molecular orbital (LUMO) level of the Hole Block Layer (HBL) and the absolute value of the lowest unoccupied molecular orbital (LUMO) level of the second photonic layer 611b is less than or equal to 0.2 eV.

[0225] For example, the difference n1 between the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL) and the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second photonic layer 611b can be 0, 0.03 eV, 0.05 eV, 0.08 eV, 0.1 eV, 0.12 eV, 0.15 eV, 0.18 eV, or 0.2 eV, etc.

[0226] By ensuring that the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the Hole Block Layer (HBL) and the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the second photonic layer 611b are less than or equal to 0.2, i.e., the difference n1 between the absolute values ​​of the lowest unoccupied molecular orbital (LUMO) energy levels of the Hole Block Layer (HBL) and the second photonic layer 611b is small, the difficulty of electrons transitioning from the Hole Block Layer (HBL) to the second photonic layer 611b is lower, thus preventing electrons from transitioning too quickly from the Hole Block Layer (HBL). Electrons transition from the first light-emitting layer (HBL) to the second light-emitting sublayer 611b and from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a too quickly. This protects the electron block layer (EBL) located on the side of the first light-emitting sublayer 611a away from the second light-emitting sublayer 611b, preventing the electron block layer (EBL) from failing. At the same time, it also ensures that electrons are transported from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a. This is beneficial for the recombination of holes and electrons in the first light-emitting sublayer 611a, so that most or all of the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 is located in the first light-emitting sublayer 611a. This is beneficial for improving the recombination efficiency of electrons and holes in the first light-emitting layer 61, thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0227] In some embodiments, please continue to refer to Figure 12, where the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) is greater than or equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL).

[0228] In other words, the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) is lower than or equal to the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL).

[0229] It should be noted that Figure 12 only shows the case where the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) is greater than the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL). However, the embodiments of this disclosure include, but are not limited to, the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) can also be equal to the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL).

[0230] Electrons can easily transition from layers with higher Lowest Unoccupied Molecular Orbital (LUMO) energy levels to layers with lower LUMO energy levels, while electrons find it difficult to transition from layers with lower LUMO energy levels to layers with higher LUMO energy levels. By setting the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) to be lower than or equal to the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL), when the sub-pixel F is subjected to an external electric field, electrons are less likely to transition from the electron transport layer (ETL) to the hole block layer (HBL). This prevents electrons from transitioning too quickly from the electron transport layer (ETL) to the hole block layer (HBL), and consequently, prevents electrons from transitioning too quickly from the hole block layer (HBL) to the first light-emitting layer (HBL) via the second light-emitting layer (611b). This helps protect the electron block layer (HBL) located on the side of the first light-emitting layer (HBL) away from the second light-emitting layer (HBL). Electron Block Layer (EBL) is used to prevent the Electron Block Layer (EBL) from failing, thereby improving the lifespan of the display panel 10.

[0231] For example, referring to Figure 12, the difference n2 between the absolute values ​​of the lowest unoccupied molecular orbital (LUMO) energy levels of the electron transport layer (ETL) and the lowest unoccupied molecular orbital (LUMO) energy levels of the hole block layer (HBL) is less than or equal to 0.2 eV.

[0232] For example, the difference n2 between the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the electron transport layer (ETL) and the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level of the hole block layer (HBL) can be 0, 0.03 eV, 0.05 eV, 0.08 eV, 0.1 eV, 0.12 eV, 0.15 eV, 0.18 eV, or 0.2 eV, etc.

[0233] By ensuring that the absolute value of the lowest unoccupied molecular orbital (LUMO) energy level in the electron transport layer (ETL) is less than or equal to 0.2, i.e., the difference n2 between the absolute values ​​of the LUMO energy levels in the ETL and the Hole Block Layer (HBL) is small, the difficulty of electrons transitioning from the ETL to the HBL is reduced. This avoids electrons from rapidly transitioning from the ETL to the HBL. This system prevents electrons from rapidly transitioning from the hole block layer (EBL) to the hole block layer (HBL) via the second light-emitting layer (HBL) and then to the first light-emitting layer (HBL) via the second light-emitting layer (HBL). It also protects the electron block layer (EBL) located on the side of the first light-emitting layer (HBL) away from the second light-emitting layer (HBL), preventing EBL failure while ensuring that electrons sequentially pass through the electron transport layer (ETL) and the hole block layer (HBL). The transmission of light from the second light-emitting sublayer 611b to the first light-emitting sublayer 611a facilitates the recombination of holes and electrons in the first light-emitting sublayer 611a. This results in most or all of the recombination region (i.e., the light-emitting region) M of the first light-emitting layer 61 being located in the first light-emitting sublayer 611a, which helps to improve the recombination efficiency of electrons and holes in the first light-emitting layer 61. This, in turn, reduces the bias voltage required by the display panel 10 and improves the luminous efficiency and performance of the display panel 10.

[0234] In some embodiments, as shown in Figures 13A, 13B, 13C, 14A, 14B, 14C, and 15, Figures 13A, 13B, 13C, 14A, 14B, 14C, and 15 are film layer structure diagrams of sub-pixels F within a display panel 10 according to some embodiments. When the plurality of sub-pixels F within the display panel 10 includes a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3, and the first color sub-pixel F1 is a red sub-pixel, the second color sub-pixel F2 is a green sub-pixel, and the third color sub-pixel F3 is a blue sub-pixel, the light-emitting layer 6 within the first color sub-pixel F1 (i.e., the red sub-pixel) is a red light-emitting layer 6a, the light-emitting layer 6 within the second color sub-pixel F2 (i.e., the green sub-pixel) is a green light-emitting layer 6b, and the light-emitting layer 6 within the third color sub-pixel F3 (i.e., the blue sub-pixel) is a blue light-emitting layer 6c.

[0235] At least one of the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel), and the blue emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) constitutes the first emitting layer 61. That is, at least one of the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel), and the blue emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) adopts the aforementioned design regarding the electron mobility, hole mobility, thickness, highest occupied molecular orbital (HOMO) level, and lowest unoccupied molecular orbital (LUMO) level of the first emitting layer 61.

[0236] For example, please continue to refer to Figures 13A, 13B and 13C, one of the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the first light-emitting layer 61.

[0237] For example, referring to Figure 13A, the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) can be the first light-emitting layer 61, and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the second light-emitting layer 62.

[0238] By making the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) the first light-emitting layer 61, the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61) can be reduced. This makes the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61) smaller, which facilitates the recombination of electrons and holes as charge carriers in the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61). This is beneficial to improving the recombination efficiency of electrons and holes in the red light-emitting layer 6a (i.e., the first light-emitting layer 61), thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0239] For example, please refer to Figure 13B. The green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) can be the first light-emitting layer 61, and the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the second light-emitting layer 62.

[0240] For the same reason as in the embodiment shown in Figure 13A, where the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) is the first light-emitting layer 61, by making the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) the first light-emitting layer 61, the recombination efficiency of electrons and holes in the green light-emitting layer 6b (i.e., the first light-emitting layer 61) can be improved, thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0241] For example, please refer to Figure 13C. The blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the first light-emitting layer 61, and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) and the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) can be the second light-emitting layer 62.

[0242] For the same reason as in the embodiment shown in Figure 13A, where the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) is the first light-emitting layer 61, by making the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) the first light-emitting layer 61, the recombination efficiency of electrons and holes in the blue light-emitting layer 6c (i.e., the first light-emitting layer 61) can be improved, thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0243] For example, please continue to refer to Figures 14A, 14B and 14C, two of the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the first light-emitting layer 61.

[0244] For example, referring to Figure 14A, the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) can both be the first light-emitting layer 61, and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the second light-emitting layer 62.

[0245] By making the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) both the red emitting layer 6a (i.e., the first emitting layer 61) and the green emitting layer 6b (i.e., the first emitting layer 61) recombine, the recombination region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61) and the green emitting layer 6b (i.e., the first emitting layer 61) is reduced, and the recombination region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61) and the green emitting layer 6b (i.e., the first emitting layer 61) is smaller, which facilitates the recombination of electrons and holes in the red emitting layer 6a (i.e., the first emitting layer 61) and the green emitting layer 6b (i.e., the first emitting layer 61), thereby improving the recombination efficiency of electrons and holes in the red emitting layer 6a (i.e., the first emitting layer 61) and the green emitting layer 6b (i.e., the first emitting layer 61), further reducing the bias voltage required by the display panel 10, and further improving the luminous efficiency and performance of the display panel 10.

[0246] For example, referring to Figure 14B, the blue emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) and the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) can be the first emitting layer 61, and the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) can be the second emitting layer 62.

[0247] For the same reason as in the embodiment shown in Figure 14A, where the red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) are both first light-emitting layers 61, by making the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) both first light-emitting layers 61, the recombination efficiency of electrons and holes in the blue light-emitting layer 6c (i.e., the first light-emitting layer 61) and the green light-emitting layer 6b (i.e., the first light-emitting layer 61) can be improved, thereby further reducing the bias voltage required by the display panel 10 and further improving the luminous efficiency and performance of the display panel 10.

[0248] For example, please continue to refer to Figure 14C. The red light-emitting layer 6 in the first color sub-pixel F1 (i.e., the red sub-pixel) and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can be the first light-emitting layer 61, and the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) can be the second light-emitting layer 62.

[0249] For the same reason as in the embodiment shown in Figure 14A, where the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel) are both first emitting layers 61, by making the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) and the blue emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) both first emitting layers 61, the recombination efficiency of electrons and holes in the red emitting layer 6a (i.e., the first emitting layer 61) and the blue emitting layer 6c (i.e., the first emitting layer 61) can be improved, thereby further reducing the bias voltage required by the display panel 10 and further improving the luminous efficiency and performance of the display panel 10.

[0250] For example, please continue to refer to Figure 15. The red light-emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green light-emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel), and the blue light-emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) can all be the first light-emitting layer 61.

[0251] By making the red emitting layer 6a in the first color sub-pixel F1 (i.e., the red sub-pixel), the green emitting layer 6b in the second color sub-pixel F2 (i.e., the green sub-pixel), and the blue emitting layer 6c in the third color sub-pixel F3 (i.e., the blue sub-pixel) all the first emitting layer 61, the composite region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61), the green emitting layer 6b (i.e., the first emitting layer 61), and the blue emitting layer 6c (i.e., the first emitting layer 61) can be reduced simultaneously. This makes the composite region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61), the green emitting layer 6b (i.e., the first emitting layer 61), and the blue emitting layer 6c (i.e., the first emitting layer 61) smaller, which facilitates the movement of electrons and holes as charge carriers in the red emitting layer. The recombination in the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61), the green light-emitting layer 6b (i.e., the first light-emitting layer 61), and the blue light-emitting layer 6c (i.e., the first light-emitting layer 61) is beneficial to improve the recombination efficiency of electrons and holes in the red light-emitting layer 6a (i.e., the first light-emitting layer 61), the green light-emitting layer 6b (i.e., the first light-emitting layer 61), and the blue light-emitting layer 6c (i.e., the first light-emitting layer 61), which can further reduce the bias voltage required by the display panel 10 and further improve the luminous efficiency and performance of the display panel 10.

[0252] In some embodiments, as shown in Figures 16A, 16B, and 17, these figures are film layer structure diagrams of a sub-pixel F within a display panel 10 according to some embodiments. The sub-pixel F within the display panel 10 includes at least two stacked light-emitting layers 6 and at least one charge generation layer (CGL) 7. A charge generation layer (CGL) 7 is disposed between any two adjacent light-emitting layers 6. The charge generation layer (CGL) 7 can connect adjacent light-emitting layers 6 in series to achieve a tandem light emission (TEL) design.

[0253] On the one hand, due to the increased number of light-emitting layers 6 and the ability of the charge-generating layer (CGL) 7 to reduce the driving voltage and generate new charge carriers, the luminous efficiency of the light-emitting layer 6 can be increased several times. On the other hand, at the same brightness, the current density of the display panel 10 with a tandem EL design is reduced compared to that of the display panel 10 with a single-layer light-emitting design, which is beneficial to extending the lifespan of the display panel 10.

[0254] It should be noted that Figures 16A, 16B, and 17 are only used as examples of sub-pixels F within the display panel 10, which include two stacked light-emitting layers 6 and one charge generation layer (CGL) 7, to illustrate some embodiments of this disclosure. However, embodiments of this disclosure include, but are not limited to, these examples, and the number of light-emitting layers 6 and charge generation layers (CGL) 7 in the sub-pixels F within the display panel 10 can be set according to actual needs.

[0255] For example, the charge generation layer (CGL) 7 can be configured to generate, transport, and inject charge carriers.

[0256] For example, the charge generation layer (CGL) 7 may include an N-type charge generation layer (n-CGL) and a P-type charge generation layer (p-CGL).

[0257] N-type charge generation layers (n-CGLs) may include, for example, organic electron transport layer (ETL) materials doped with metal materials.

[0258] P-type charge generation layer (p-CGL) can include, for example, organic hole transport layer (HTL) materials doped with p-type light-emitting dopants (p-dopant, PD).

[0259] In some embodiments, please continue to refer to Figures 16A and 16B, in the sub-pixel F, one of the two light-emitting layers 6 located on opposite sides of the charge generation layer (CGL) 7 is the first light-emitting layer 61, and the other is the second light-emitting layer 62, that is, the charge generation layer (CGL) 7 is located between the first light-emitting layer 61 and the second light-emitting layer 62.

[0260] By including two light-emitting layers 6 in the sub-pixel F, and one of the light-emitting layers 6 being the first light-emitting layer 61, the luminous efficiency of the light-emitting layer 6 is increased several times, the current density of the display panel 10 is reduced, the bias voltage required by the display panel 10 is reduced, and the luminous efficiency and performance of the display panel 10 are improved.

[0261] Specifically, taking the first color sub-pixel F1 (i.e., the red sub-pixel) as an example, please continue to refer to Figures 16A and 16B. Within the first color sub-pixel F1 (i.e., the red sub-pixel), the light-emitting layer 6 is a red light-emitting layer 6a. The first color sub-pixel F1 (i.e., the red sub-pixel) includes two layers of red light-emitting layers 6a and a charge generation layer (CGL) 7 located between the two layers of red light-emitting layers 6a. Since the number of red light-emitting layers 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) is two, compared to the first color sub-pixel F1 (i.e., the red sub-pixel) with only one layer of red light-emitting layers 6a, the number of red light-emitting layers 6a is increased by a factor of two. Furthermore, the charge generation layer (CGL) 7 can reduce the driving voltage and generate new charge carriers, thus increasing the luminous efficiency of the red light-emitting layers 6a by a factor of two. Moreover, at the same brightness, the current density of the display panel 10 with a tandem EL design is reduced compared to the display panel 10 with a single-layer light-emitting design, which is beneficial for extending the lifespan of the display panel 10.

[0262] Furthermore, the two red light-emitting layers 6a within the first color sub-pixel F1 (i.e., the red sub-pixel) include a first light-emitting layer 61 and a second light-emitting layer 62. By including a first light-emitting layer 61 within the two red light-emitting layers 6a of the first color sub-pixel F1 (i.e., the red sub-pixel), the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61) can be reduced. This smaller recombination region facilitates the recombination of electrons and holes as charge carriers within the recombination region (i.e., the light-emitting region) of the red light-emitting layer 6a (i.e., the first light-emitting layer 61), thereby improving the recombination efficiency of electrons and holes in the red light-emitting layer 6a (i.e., the first light-emitting layer 61), thus reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0263] Similarly, please refer to Figures 16A and 16B. When sub-pixel F is the second color sub-pixel F2 (i.e., the green sub-pixel), the light-emitting layer 6 within the second color sub-pixel F2 (i.e., the green sub-pixel) is a green light-emitting layer 6b. The two green light-emitting layers 6b within the second color sub-pixel F2 (i.e., the green sub-pixel) include a first light-emitting layer 61 and a second light-emitting layer 62. By including a first light-emitting layer 61 in the two green light-emitting layers 6b within the second color sub-pixel F2 (i.e., the green sub-pixel), the recombination region (i.e., the light-emitting region) of the green light-emitting layer 6b (i.e., the first light-emitting layer 61) can be reduced. This makes the recombination region (i.e., the light-emitting region) of the green light-emitting layer 6b (i.e., the first light-emitting layer 61) smaller, which facilitates the recombination of electrons and holes as charge carriers in the recombination region (i.e., the light-emitting region) of the green light-emitting layer 6b (i.e., the first light-emitting layer 61). This is beneficial to improving the recombination efficiency of electrons and holes in the green light-emitting layer 6b (i.e., the first light-emitting layer 61), thereby reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0264] When sub-pixel F is the third color sub-pixel F3 (i.e., the blue sub-pixel), the light-emitting layer 6 within the third color sub-pixel F3 (i.e., the blue sub-pixel) is a blue light-emitting layer 6c. The two blue light-emitting layers 6c within the third color sub-pixel F3 (i.e., the blue sub-pixel) include a first light-emitting layer 61. By including a first light-emitting layer 61 within the two blue light-emitting layers 6c within the third color sub-pixel F3 (i.e., the blue sub-pixel), the recombination region (i.e., the light-emitting region) of the blue light-emitting layer 6c (i.e., the first light-emitting layer 61) can be reduced. This smaller recombination region facilitates the recombination of electrons and holes as charge carriers within the recombination region (i.e., the light-emitting region) of the blue light-emitting layer 6c (i.e., the first light-emitting layer 61), thereby improving the recombination efficiency of electrons and holes in the blue light-emitting layer 6c (i.e., the first light-emitting layer 61), thus reducing the bias voltage required by the display panel 10 and improving the luminous efficiency and performance of the display panel 10.

[0265] It should be noted that when the multiple sub-pixels F within the display panel 10 include a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3, Figures 16A and 16B only illustrate the example where each of the first color sub-pixels F1, F2, and F3 includes a first light-emitting layer 61. However, the embodiments of this disclosure include, but are not limited to, this. For example, two of the first color sub-pixels F1, F2, and F3 may each include a first light-emitting layer 61, while the remaining one does not. As another example, one of the first color sub-pixels F1, F2, and F3 may include a first light-emitting layer 61, while the other two do not.

[0266] For example, please continue to refer to FIG16A, the second light-emitting layer 62 may be closer to the first electrode 311 than the first light-emitting layer 61.

[0267] Alternatively, please refer to Figure 16B, where the second light-emitting layer 62 can also be farther away from the first electrode 311 than the first light-emitting layer 61.

[0268] In some embodiments, please continue referring to FIG17, the sub-pixel F in the display panel 10 includes at least two stacked first light-emitting layers 61, and a charge generation layer (CGL) 7 is disposed between any two adjacent first light-emitting layers 61. That is, the light-emitting layers 6 in the sub-pixel F in the display panel 10 are all first light-emitting layers 61.

[0269] By including at least two light-emitting layers 6 in the sub-pixel F, and both light-emitting layers being first light-emitting layers 61, the luminous efficiency of the light-emitting layer 6 is increased several times, the current density of the display panel 10 is reduced, the bias voltage required by the display panel 10 is further reduced, and the luminous efficiency and performance of the display panel 10 are further improved.

[0270] Specifically, taking the first color sub-pixel F1 (i.e., the red sub-pixel) as an example, please continue referring to Figure 17. Within the first color sub-pixel F1 (i.e., the red sub-pixel), the light-emitting layer 6 is a red light-emitting layer 6a. The first color sub-pixel F1 (i.e., the red sub-pixel) includes at least two layers of red light-emitting layers 6a and a charge generation layer (CGL) 7 located between any two adjacent layers of red light-emitting layers 6a. Since the number of red light-emitting layers 6a in the first color sub-pixel F1 (i.e., the red sub-pixel) is at least two, compared to a first color sub-pixel F1 (i.e., the red sub-pixel) with only one layer of red light-emitting layers 6a, the number of red light-emitting layers 6a is increased by a factor of two. Furthermore, the charge generation layer (CGL) 7 can reduce the driving voltage and generate new charge carriers, thus increasing the luminous efficiency of the red light-emitting layers 6a by a factor of two. Moreover, at the same brightness, the current density of the display panel 10 with a tandem EL design is reduced compared to the display panel 10 with a single-layer light-emitting design, which is beneficial for extending the lifespan of the display panel 10.

[0271] Furthermore, at least two red emitting layers 6a within the first color sub-pixel F1 (i.e., the red sub-pixel) are both first emitting layers 61. By making at least two red emitting layers 6a within the first color sub-pixel F1 (i.e., the red sub-pixel) both first emitting layers 61, the recombination region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61) can be further reduced. This smaller recombination region facilitates the recombination of electrons and holes as charge carriers within the recombination region (i.e., the emitting region) of the red emitting layer 6a (i.e., the first emitting layer 61), thereby further improving the recombination efficiency of electrons and holes in the red emitting layer 6a (i.e., the first emitting layer 61), further reducing the bias voltage required by the display panel 10, and further improving the luminous efficiency and performance of the display panel 10.

[0272] Similarly, when the aforementioned sub-pixel F is the second color sub-pixel F2 (i.e., the green sub-pixel) or the third color sub-pixel F3 (i.e., the blue sub-pixel), the bias voltage required by the display panel 10 can be further reduced, and the luminous efficiency and performance of the display panel 10 can be further improved.

[0273] It should be noted that when the multiple sub-pixels F within the display panel 10 include a first color sub-pixel F1, a second color sub-pixel F2, and a third color sub-pixel F3, Figure 17 only illustrates the example where the light-emitting layer 6 in the first color sub-pixel F1, the second color sub-pixel F2, and the third color sub-pixel F3 is the first light-emitting layer 61. However, the embodiments of this disclosure include, but are not limited to, this. For example, the light-emitting layer 6 in two of the first color sub-pixel F1, the second color sub-pixel F2, and the third color sub-pixel F3 can all be the first light-emitting layer 61, and the remaining one can include the second light-emitting layer 62. As another example, the light-emitting layer 6 in one of the first color sub-pixel F1, the second color sub-pixel F2, and the third color sub-pixel F3 can all be the first light-emitting layer 61, and the remaining two can include the second light-emitting layer 62.

[0274] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A display panel, comprising: A first electrode, a first light-emitting layer, and a second electrode are sequentially stacked. The first electrode is configured to inject holes into the first light-emitting layer, and the second electrode is configured to inject electrons into the first light-emitting layer; The first light-emitting layer includes at least two light-emitting sub-layers stacked together; The hole mobility of each of the light-emitting sublayers is less than the electron mobility of the light-emitting sublayer.

2. The display panel according to claim 1, wherein, The ratio of electron mobility to hole mobility in each of the light-emitting sublayers is greater than or equal to 10.

3. The display panel according to claim 1 or 2, wherein, The first light-emitting layer includes a first light-emitting sub-layer and a second light-emitting sub-layer adjacent to the first light-emitting sub-layer, wherein the first light-emitting sub-layer is closer to the first electrode than the second light-emitting sub-layer; the thickness of the first light-emitting sub-layer is less than the thickness of the second light-emitting sub-layer.

4. The display panel according to any one of claims 1 to 3, wherein, The thickness of the first luminescent sublayer is 5 nm to 10 nm.

5. The display panel according to any one of claims 1 to 4, wherein, The first light-emitting layer includes a first light-emitting sub-layer and a second light-emitting sub-layer adjacent to the first light-emitting sub-layer, wherein the first light-emitting sub-layer is closer to the first electrode than the second light-emitting sub-layer; The electron mobility of the second luminescent sublayer is greater than that of the first luminescent sublayer.

6. The display panel according to claim 5, wherein, The first light-emitting layer includes at least three light-emitting sub-layers, and the electron mobility of the at least three light-emitting sub-layers increases sequentially along the direction from the first electrode to the second electrode.

7. The display panel according to any one of claims 1 to 6, wherein, The first light-emitting layer includes a first light-emitting sub-layer and a second light-emitting sub-layer adjacent to the first light-emitting sub-layer, wherein the first light-emitting sub-layer is closer to the first electrode than the second light-emitting sub-layer; The hole mobility of the second luminescent sublayer is greater than or equal to the hole mobility of the first luminescent sublayer.

8. The display panel according to claim 7, wherein, The first light-emitting layer includes at least three light-emitting sub-layers, and the hole mobility of the at least three light-emitting sub-layers increases sequentially along the direction from the first electrode to the second electrode.

9. The display panel according to any one of claims 1 to 8, wherein, The absolute value of the highest occupied molecular orbital energy level of the first luminescent sublayer of the first luminescent layer is less than or equal to the absolute value of the highest occupied molecular orbital energy level of the second luminescent sublayer of the first luminescent layer. The absolute value of the lowest unoccupied molecular orbital energy level of the first luminescent sublayer of the first luminescent layer is less than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the second luminescent sublayer of the first luminescent layer.

10. The display panel according to any one of claims 1 to 9, wherein, The display panel further includes a hole transport layer and an electron blocking layer stacked sequentially along a direction away from the first electrode, wherein the hole transport layer and the electron blocking layer are located between the first light-emitting sublayer and the first electrode; The absolute value of the highest occupied molecular orbital energy level of the hole transport layer is less than or equal to the absolute value of the highest occupied molecular orbital energy level of the electron blocking layer.

11. The display panel according to claim 10, wherein, The absolute value of the highest occupied molecular orbital energy level of the electron blocking layer is greater than or equal to the absolute value of the highest occupied molecular orbital energy level of the first luminescent sublayer.

12. The display panel according to any one of claims 1 to 11, wherein, The display panel further includes a hole blocking layer located between the second light-emitting sub-layer and the second electrode; The absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the second photonic layer.

13. The display panel according to claim 12, wherein, The difference between the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer and the absolute value of the lowest unoccupied molecular orbital energy level of the second photonic layer is less than or equal to 0.2 eV.

14. The display panel according to any one of claims 1 to 13, wherein, The display panel further includes an electron transport layer located between the hole blocking layer and the second electrode; The absolute value of the lowest unoccupied molecular orbital energy level of the electron transport layer is greater than or equal to the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer.

15. The display panel according to claim 14, wherein, The difference between the absolute value of the lowest unoccupied molecular orbital energy level of the electron transport layer and the absolute value of the lowest unoccupied molecular orbital energy level of the hole blocking layer is less than or equal to 0.2 eV.

16. The display panel according to any one of claims 1 to 15, wherein, The display panel includes a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer; At least one of the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer is the first light-emitting layer.

17. The display panel according to claim 16, wherein, The red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer are all the first light-emitting layer.

18. The display panel according to any one of claims 1 to 17, wherein, The display panel includes at least two layers of the first light-emitting layer stacked together; The display panel further includes at least one charge generation layer, and one charge generation layer is disposed between any two adjacent first light-emitting layers.

19. The display panel according to any one of claims 1 to 17, wherein, The display panel further includes a second light-emitting layer and a charge-generating layer, wherein the charge-generating layer is located between the first light-emitting layer and the second light-emitting layer; The second light-emitting layer is a single-layer structure; The second light-emitting layer is closer to or farther away from the first electrode than the first light-emitting layer.

20. A display device, comprising: The display panel as described in any one of claims 1 to 19; A cover plate is disposed on the light-emitting side of the display panel.

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