Display panel, manufacturing method thereof and display device

Abstract

This application relates to a display panel and its manufacturing method, as well as a display device. The display panel includes: a substrate; a pixel defining layer disposed on one side of the substrate, the pixel defining layer including a plurality of pixel openings; at least one light-emitting device disposed in at least one pixel opening, the light-emitting device including a first electrode, a first heterojunction electrode, a first light-emitting unit, a charge generating layer, a second light-emitting unit, and a second electrode stacked sequentially; the first heterojunction electrode includes at least one heterojunction unit stacked between the first electrode and the first light-emitting unit. The equivalent capacitance of the first light-emitting unit includes the capacitance formed by the first heterojunction electrode and the charge generating layer. By adjusting the first heterojunction electrode, the equivalent capacitance of the first light-emitting unit can be adjusted to match the capacitance of the second light-emitting unit, thereby improving or even eliminating transient overshoot during voltage switching, improving brightness flicker during low grayscale screen switching, improving display effect, and optimizing user experience.

Description

Technical Field

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

[0002] Tandem organic light-emitting diode (OLED) devices offer advantages such as high brightness, long lifespan, and low power consumption. A tandem OLED device typically consists of two or more light-emitting units connected in series via a charge generation layer (CGL). This allows multiple light-emitting units to emit light simultaneously at the same current density, thereby achieving high brightness while extending the device's lifespan.

[0003] However, stacked OLED devices may exhibit an abnormal phenomenon of instantaneous brightness overshoot during low grayscale screen transitions, resulting in visible brightness flicker that severely affects display quality. Summary of the Invention

[0004] Therefore, it is necessary to provide a display panel, its manufacturing method, and a display device that improve the problem of instantaneous brightness flicker during low grayscale screen switching, in order to address the aforementioned technical issues.

[0005] In a first aspect, this application provides a display panel, comprising:

[0006] substrate;

[0007] A pixel defining layer is disposed on one side of the substrate, and the pixel defining layer includes a plurality of pixel openings;

[0008] At least one light-emitting device is disposed in at least one of the pixel openings, and the light-emitting device includes a first electrode, a first heterojunction electrode, a first light-emitting unit, a charge-generating layer, a second light-emitting unit, and a second electrode stacked in sequence.

[0009] The first heterojunction electrode includes at least one heterojunction unit stacked between the first electrode and the first light-emitting unit.

[0010] In one embodiment, the first electrode is disposed on the substrate, the pixel defining layer covers the end of the first electrode, and the pixel opening exposes a portion of the first electrode;

[0011] The first heterojunction electrode covers the first electrode exposed by the pixel opening and extends to the pixel defining layer on the sidewall of the pixel opening;

[0012] Preferably, the first heterojunction electrode further extends to the top surface of the pixel defining layer on the side opposite to the substrate.

[0013] In one embodiment, the first heterojunction electrode includes at least a first sublayer and a second sublayer stacked between the first electrode and the first light-emitting unit, wherein the first sublayer and the second sublayer have opposite conductivity types, forming a first heterojunction unit;

[0014] Preferably, the first heterojunction electrode further includes a third sublayer, which is disposed between the second sublayer and the first light-emitting unit; the third sublayer has the opposite conductivity type to the second sublayer, forming a second heterojunction unit;

[0015] Preferably, the first sub-layer and the third sub-layer are n-type conductive layers, and the second sub-layer is a p-type conductive layer; or, the first sub-layer and the third sub-layer are p-type conductive layers, and the second sub-layer is an n-type conductive layer.

[0016] In one embodiment, the light-emitting device further includes:

[0017] A second heterojunction electrode is disposed between the second light-emitting unit and the second electrode, and the second heterojunction electrode includes at least one heterojunction unit stacked between the second light-emitting unit and the second electrode.

[0018] In one embodiment, the second heterojunction electrode includes at least a fourth sublayer and a fifth sublayer stacked between the second light-emitting unit and the second electrode, wherein the fourth sublayer and the fifth sublayer have opposite conductivity types, forming a third heterojunction unit;

[0019] Preferably, the second heterojunction electrode further includes a sixth sublayer, which is disposed between the fifth sublayer and the second electrode; the sixth sublayer has the opposite conductivity type to the fifth sublayer, forming a fourth heterojunction unit;

[0020] Preferably, the fourth sub-layer and the sixth sub-layer are n-type conductive layers, and the fifth sub-layer is a p-type conductive layer; or, the fourth sub-layer and the sixth sub-layer are p-type conductive layers, and the fifth sub-layer is an n-type conductive layer.

[0021] In one embodiment, the number of heterojunction units in the first heterojunction electrode is the same as the number of heterojunction units in the second heterojunction electrode.

[0022] In one embodiment, each heterojunction unit includes two sub-layers with opposite conductivity types. The sub-layer in the first heterojunction electrode that contacts the first light-emitting unit has a first conductivity type, and the sub-layer in the second heterojunction electrode that contacts the second light-emitting unit has a second conductivity type. The first conductivity type and the second conductivity type are different.

[0023] In one embodiment, the first light-emitting unit includes a first hole transport layer, a first light-emitting functional layer, and a first electron transport layer sequentially stacked on the first heterojunction electrode.

[0024] The second light-emitting unit includes a second hole transport layer, a second light-emitting functional layer, and a second electron transport layer, which are sequentially stacked on the charge generation layer;

[0025] The charge generation layer includes a first charge generation sublayer and a second charge generation sublayer stacked between the first light-emitting unit and the second light-emitting unit;

[0026] Preferably, the first heterojunction electrode is reused as the first hole transport layer of the first light-emitting unit;

[0027] Preferably, the second heterojunction electrode is reused as the second electron transport layer of the second light-emitting unit.

[0028] Secondly, this application provides a method for manufacturing a display panel, comprising the following steps:

[0029] Provide substrate;

[0030] A first electrode is formed on the substrate;

[0031] A pixel defining layer is formed on the substrate, and the pixel defining layer is patterned to form a plurality of pixel openings, at least one of the pixel openings exposing a portion of the surface of at least one first electrode;

[0032] At least two sublayers of opposite conductivity types are sequentially deposited to form a first heterojunction electrode, which covers the first electrode exposed by the pixel opening and extends to the pixel defining layer on the sidewall of the pixel opening.

[0033] A first light-emitting unit, a charge-generating layer, a second light-emitting unit, and a second electrode are sequentially formed in the pixel opening. The first light-emitting unit, the charge-generating layer, the second light-emitting unit, and the second electrode are sequentially stacked on the first heterojunction electrode.

[0034] Thirdly, this application provides a display device including a display panel as described in the first aspect.

[0035] The display panel and its manufacturing method and display device of this application add a first heterojunction electrode between the first electrode and the first light-emitting unit. The equivalent capacitance of the first light-emitting unit includes the capacitance formed by the first heterojunction electrode and the charge generation layer. The equivalent capacitance of the first light-emitting unit can be adjusted by adjusting the first heterojunction electrode (material selection, doping concentration, thickness and coverage area) to match the capacitance of the second light-emitting unit. When switching between low grayscale images, the transient overshoot during voltage switching can be improved or even eliminated, the brightness flicker during low grayscale image switching can be improved, the display effect can be improved and the user experience can be optimized. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is an equivalent circuit diagram of a multilayer OLED device in related technologies;

[0038] Figure 2 This is a brightness timing diagram for low grayscale screen switching in a stacked OLED device in related technologies.

[0039] Figure 3 This is a schematic diagram of the structure of a display panel provided in one embodiment of this application;

[0040] Figure 4 An equivalent circuit diagram of a light-emitting device provided in an embodiment of this application;

[0041] Figure 5 A brightness timing diagram of low grayscale screen switching for a light-emitting device provided in an embodiment of this application;

[0042] Figure 6 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application;

[0043] Figure 7 This is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this application;

[0044] Figure 8 This is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this application;

[0045] Figure 9 This is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this application;

[0046] Figure 10A process flow diagram illustrating a method for manufacturing a display panel according to an embodiment of this application;

[0047] Figure 11 This is a schematic diagram of the structure of a display device provided in an embodiment of this application.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Display device; 100. Display panel; 11. Substrate; 12. Pixel limiting layer; 12a. Pixel opening; 20. Light-emitting device; 21. First electrode; 22. First heterojunction electrode; 221. First sublayer; 222. Second sublayer; 223. Third sublayer; 23. Charge generation layer; 231. First charge generation sublayer; 232. Second charge generation sublayer; 24. First light-emitting unit; 241. First hole transport layer; 242. First light-emitting functional layer; 243. First electron transport layer; 25. Second light-emitting unit; 251. Second hole transport layer; 252. Second light-emitting functional layer; 253. Second electron transport layer; 26. Second heterojunction electrode; 261. Fourth sublayer; 262. Fifth sublayer; 263. Sixth sublayer; 27. Second electrode. Detailed Implementation

[0050] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] When describing positional relationships, unless otherwise specified, when an element such as a layer, film, or substrate is referred to as being "on" another element, it may be directly on the other element or there may be intermediate elements present. Furthermore, when a layer is referred to as being "below" another layer, it may be directly below it or there may be one or more light-emitting units present. It is also understood that when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or there may be one or more light-emitting units present.

[0053] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the components are shown in the drawings only as examples and not necessarily to actual scale.

[0054] As described in the background section, stacked OLED devices exhibit a transient brightness overshoot phenomenon during low grayscale scene transitions, resulting in visible brightness flicker that severely impacts display quality. The reason for this is that stacked OLED devices include at least a first light-emitting unit 110' and a second light-emitting unit 120' connected in series. The first light-emitting unit 110' is located between the anode and the charge generation layer CGL, while the second light-emitting unit 120' is located between the charge generation layer CGL and the cathode. Due to manufacturing limitations, the second light-emitting unit 120' typically extends to the top of the pixel definition layer, resulting in an effective area much larger than that of the first light-emitting unit 110'.

[0055] Reference Figure 1 In the equivalent circuit of the stacked OLED device, the first light-emitting unit 110' and the second light-emitting unit 120' constitute different capacitors. The equivalent capacitance C1 of the first light-emitting unit 110' is composed of the anode corresponding to the pixel opening and the charge generation layer CGL, and the capacitance value of the equivalent capacitance C1 is limited by the pixel opening. The equivalent capacitance of the second light-emitting unit 120' is composed of the charge generation layer CGL and the cathode. The cathode of the stacked OLED device is deposited across the entire surface, not only forming in the pixel opening region but also extending to the pixel limiting layer, where a parasitic capacitance C is formed. pdl The equivalent capacitance of the second light-emitting unit 120' includes the equivalent capacitance C2 of the pixel aperture region and the corresponding parasitic capacitance C on the pixel limiting layer. pdl The capacitance value of the second light-emitting unit 120' is much larger than that of the first light-emitting unit 110', and the capacitances of the two light-emitting units are seriously mismatched.

[0056] Reference Figure 3 As shown, when switching between low grayscale images, the driving voltage changes instantaneously. Due to the large difference in capacitance between the two light-emitting units, the charge is redistributed among the capacitances of the two light-emitting units. This causes the voltage that the first light-emitting unit 110' experiences instantaneously to be much higher than its steady-state operating voltage, resulting in an instantaneous brightness overshoot. The brightness of the display panel will be significantly higher than the brightness corresponding to the target grayscale, and then gradually decrease and stabilize to a normal brightness level. This affects the viewing comfort and image quality uniformity, seriously impacting display quality and user experience.

[0057] In a first aspect, this exemplary embodiment provides a display panel 100, which may be a flexible display panel 100 having only display function, or it may include a flexible display panel 100 with touch function. The flexible display panel 100 may, for example, be a flexible OLED (Organic Light-Emitting Diode) display panel 100, an active-matrix organic light-emitting diode display panel 100 (AMOLED), or other types of flexible display panels 100.

[0058] Reference Figure 3 As shown, the display panel 100 of this embodiment includes a substrate 11, a pixel defining layer 12, and at least one light-emitting device 20. The substrate 11 can be flexible polyimide (PI), rigid glass, or a thin metal sheet, etc. This embodiment will not discuss substrates of other materials in detail here; those skilled in the art can select different types of materials according to actual needs. The pixel defining layer 12 is disposed on one side of the substrate 11. The pixel defining layer 12 includes a plurality of pixel openings 12a, which define the light-emitting area of ​​the light-emitting device 20. The pixel defining layer 12 isolates adjacent light-emitting devices 20 to prevent leakage and optical crosstalk. The pixel defining layer 12 is made of organic or inorganic materials. For example, the pixel defining layer 12 is formed using at least one inorganic insulating material selected from silicon nitride (SiNx), silicon oxide (SiOx), and silicon oxynitride (SiON).

[0059] At least one light-emitting device 20 is disposed in at least one pixel opening 12a, wherein each light-emitting device 20 is disposed corresponding to at least one pixel opening 12a, and the light-emitting device 20 includes a first electrode 21, a first heterojunction electrode 22, a first light-emitting unit 24, a charge generating layer 23, a second light-emitting unit 25 and a second electrode 27 sequentially stacked in the corresponding pixel opening 12a; wherein the first heterojunction electrode 22 includes at least one heterojunction unit stacked between the first electrode 21 and the first light-emitting unit 24.

[0060] For example, the first electrode 21 can be an anode, and the second electrode 27 can be a cathode. The first electrode 21 can be a composite layer of a transparent conductive oxide (such as ITO) and a highly reflective metal (such as a silver alloy). The second electrode 27 uses a semi-transparent or transparent conductive material, such as a magnesium-silver alloy, a transparent conductive oxide (such as ITO), or a combination thereof, to achieve light emission. The first light-emitting unit 24 is used to emit light of a first color (e.g., red, green, or blue light), and the second light-emitting unit 25 is used to emit light of a second color. The second light-emitting unit 25 can emit light of the same color as the first light-emitting unit 24 to enhance brightness, or it can emit light of a different color than the first light-emitting unit 24 to achieve white light emission. The charge generation layer 23 is used to generate free charge carriers under the action of an electric field to realize the series connection of the first light-emitting unit 24 and the second light-emitting unit 25.

[0061] In this embodiment, the display panel 100 adds a first heterojunction electrode 22 between the first electrode 21 and the first light-emitting unit 24. The equivalent capacitance of the first light-emitting unit 24 includes the capacitance formed by the first heterojunction electrode 22 and the charge generation layer 23. The equivalent capacitance of the first light-emitting unit 24 can be adjusted by adjusting the first heterojunction electrode 22 (material selection, doping concentration, thickness and coverage area), thereby adjusting the equivalent capacitance of the first light-emitting unit 24 to match the capacitance of the second light-emitting unit 25. When switching between low grayscale images, the transient overshoot during voltage switching can be improved or even eliminated, the brightness flicker during low grayscale image switching can be improved, the display effect can be improved, and the user experience can be optimized.

[0062] In one embodiment, reference Figure 3 The first electrode 21 is disposed on the substrate 11, the pixel limiting layer 12 covers the end of the first electrode 21, and the pixel opening 12a exposes part of the first electrode 21; the pixel opening 12a penetrates the pixel limiting layer 12 and exposes the central region corresponding to the first electrode 21, and the first electrode 21 exposed by the pixel opening 12a is the light-emitting area of ​​the light-emitting device 20.

[0063] The first heterojunction electrode 22 covers the first electrode 21 exposed in the pixel opening 12a and extends to the pixel defining layer 12 on the sidewall of the pixel opening 12a.

[0064] The first heterojunction electrode 22 covers the first electrode 21 exposed by the pixel opening 12a and extends to the sidewall of the pixel opening 12a, covering all or part of the pixel limiting layer 12 of the sidewall of the pixel opening 12a. This increases the facing area of ​​the first heterojunction electrode 22 and the charge generation layer 23, and increases the capacitance value of the capacitance C1 of the first heterojunction electrode 22 and the charge generation layer 23. This reduces the difference between the equivalent capacitance of the first light-emitting unit 24 and the equivalent capacitance of the second light-emitting unit 25, so that the equivalent capacitance of the first light-emitting unit 24 and the equivalent capacitance of the second light-emitting unit 25 are better matched. This further suppresses the brightness overshoot caused by transient charge redistribution, improves the brightness flicker when switching low grayscale images, improves the display effect, and optimizes the user experience.

[0065] It is understood that the first heterojunction electrode 22 extends to the pixel limiting layer 12 on the sidewall of the pixel opening 12a, which improves the adjustment flexibility of the equivalent capacitance of the first light-emitting unit 24. The coverage height of the first heterojunction electrode 22 on the sidewall of the pixel opening 12a can be adjusted to adjust the equivalent capacitance of the first light-emitting unit 24 so that the equivalent capacitance of the second light-emitting unit 25 is more matched.

[0066] In one embodiment, reference Figure 3 The first heterojunction electrode 22 extends not only to the pixel limiting layer 12 on the sidewall of the pixel opening 12a, but also to the top surface of the pixel limiting layer 12 on the side away from the substrate.

[0067] Reference Figure 4 The first heterojunction electrode 22 and the charge generation layer 23 form a first parasitic capacitance Cpdl1 on the pixel limiting layer 12. The equivalent capacitance of the first light-emitting unit 24 includes the capacitance C1 formed by the first heterojunction electrode 22 and the charge generation layer 23 in the pixel opening 12a region, and the first parasitic capacitance Cpdl1 formed by the first heterojunction electrode 22 and the charge generation layer 23 on the pixel limiting layer 12. pdl1 Two parts.

[0068] Reference Figure 4 The second electrode 27 is deposited over its entire surface. The equivalent capacitance of the second light-emitting unit 25 includes the capacitance C2 corresponding to the second electrode 27 and the charge generation layer 23 in the pixel opening 12a region, and the parasitic capacitance C formed by the second electrode 27 and the charge generation layer 23 on the pixel defining layer 12. pdl2 The two parts have a better match between the equivalent capacitance of the first light-emitting unit 24 and the equivalent capacitance of the second light-emitting unit 25. (Refer to...) Figure 5 The display panel in this embodiment effectively suppresses brightness overshoot caused by transient charge redistribution when switching between low grayscale scenes, improves brightness flicker when switching between low grayscale scenes, enhances display effect, and optimizes user experience.

[0069] In one embodiment, reference Figure 6 , Figure 7 As shown, the first heterojunction electrode 22 includes at least a first sublayer 221 and a second sublayer 222 stacked between the first electrode 21 and the first light-emitting unit 24. The first sublayer 221 is disposed on the first electrode 21 and is in direct contact with the first electrode 21; the second sublayer 222 is disposed on the first sublayer 221 and is in direct contact with the first sublayer 221. The first sublayer 221 and the second sublayer 222 have opposite conductivity types, forming a first heterojunction unit. The first heterojunction unit can realize carrier separation and injection without affecting the light emission of the light-emitting device 20. At the same time, the equivalent capacitance of the first light-emitting unit 24 can be adjusted using the first heterojunction electrode 22. In one example, the first sublayer 221 is an n-type conductive layer and the second sublayer 222 is a p-type conductive layer; in another example, the first sublayer 221 is a p-type conductive layer and the second sublayer 222 is an n-type conductive layer.

[0070] Preferably, refer to Figure 8 As shown, the first heterojunction electrode 22 further includes a third sublayer 223, which is disposed between the second sublayer 222 and the first light-emitting unit 24. The third sublayer 223 has the opposite conductivity type to the second sublayer 222, forming a second heterojunction unit. In this way, the first heterojunction electrode 22 includes a first heterojunction unit and a second heterojunction unit connected in series, which improves the carrier injection capability of the first heterojunction electrode 22 and enhances the ability to adjust the equivalent capacitance of the first light-emitting unit 24, making the equivalent capacitance of the first light-emitting unit 24 more matched with the equivalent capacitance of the second light-emitting unit 25.

[0071] Preferably, the first sublayer 221 and the third sublayer 223 are n-type conductive layers, and the second sublayer 222 is a p-type conductive layer; that is, the first heterojunction electrode 22 has an npn structure. Alternatively, the first sublayer 221 and the third sublayer 223 are p-type conductive layers, the second sublayer 222 is an n-type conductive layer, and the heterojunction electrode has a pnp structure.

[0072] Preferably, the first sublayer 221 and the third sublayer 223 are p-type conductive layers, the second sublayer 222 is an n-type conductive layer, and the heterojunction electrode is a pnp structure. It is understood that the first electrode 21 of the light-emitting device 20 typically uses an ITO / Ag / ITO composite layer or a silver-containing alloy with a work function of approximately 4.8 eV to 5.1 eV. If an n-type material (such as IZO, AZO, etc., with a work function of approximately 4.3 eV to 4.7 eV) is directly used to contact the first electrode 2131, an electron injection barrier may form between them due to the lower work function of the n-type material compared to the anode, which is detrimental to hole transport and may even lead to poor contact or rectification characteristics. In this embodiment, using a p-type first sublayer 221 to directly contact an electrode reduces the hole injection barrier, allowing holes to be injected more efficiently from the first electrode 21 into the first heterojunction electrode 2232, and then into the first light-emitting unit 24.

[0073] It is understood that the first heterojunction electrode 22 may also include more alternating layers (such as four or five layers) to form multiple heterojunction units connected in series.

[0074] In one embodiment, reference Figure 7 , Figure 8 , Figure 9 As shown, the light-emitting device 20 also includes a second heterojunction electrode 26, which is disposed between the second light-emitting unit 25 and the second electrode 27. The second heterojunction electrode 26 includes at least one heterojunction unit stacked between the second light-emitting unit 25 and the second electrode 27.

[0075] In this embodiment, a second heterojunction electrode 26 is added to one side of the second light-emitting unit 25. The second heterojunction electrode 26 and the charge generation layer 23 also form a capacitor C2, which, together with the parasitic capacitor C... PDL2 The two electrodes are connected in parallel to form the total equivalent capacitance of the second light-emitting unit 25. By adjusting the material selection, doping concentration, thickness, and coverage area of ​​the second heterojunction electrode 26, the size of the total equivalent capacitance of the second light-emitting unit 25 can be actively adjusted so that the total equivalent capacitance of the second light-emitting unit 25 is precisely matched with the total equivalent capacitance of the first light-emitting unit 24 after adjustment by the first heterojunction electrode 22. This allows the total equivalent capacitance of the first light-emitting unit 24 and the total equivalent capacitance of the second light-emitting unit 25 to achieve a high degree of uniformity, further suppressing the transient charge redistribution during low grayscale screen switching and more thoroughly eliminating the brightness overshoot phenomenon.

[0076] In one embodiment, reference Figure 7 , Figure 8 , Figure 9As shown, the second heterojunction electrode 26 includes at least a fourth sublayer 261 and a fifth sublayer 262 stacked between the second light-emitting unit 25 and the second electrode 27. The fourth sublayer 261 and the fifth sublayer 262 have opposite conductivity types, forming a third heterojunction unit. For example, the fourth sublayer 261 can be an n-type conductive layer and the fifth sublayer 262 can be a p-type conductive layer, or the fourth sublayer 261 can be a p-type conductive layer and the fifth sublayer 262 can be an n-type conductive layer, thereby realizing the separation and injection regulation of charge carriers.

[0077] Thus, on the one hand, through carrier separation and injection at the heterojunction interface, the second light-emitting unit 25 can operate normally without affecting the light-emitting performance of the device; on the other hand, the second heterojunction electrode 26 participates in the formation of the equivalent capacitance of the second light-emitting unit 25. By adjusting the material, thickness and doping concentration of the fourth sublayer 261 and the fifth sublayer 262, the equivalent capacitance of the second light-emitting unit 25 can be actively controlled, so that it can achieve a better match with the equivalent capacitance of the first light-emitting unit 24 after being adjusted by the first heterojunction electrode 22.

[0078] Preferably, refer to Figure 8 As shown, the second heterojunction electrode 26 also includes a sixth sublayer 263, which is disposed between the fifth sublayer 262 and the second electrode 27; the sixth sublayer 263 and the fifth sublayer 262 have opposite conductivity types, forming a fourth heterojunction unit.

[0079] In this embodiment, the second heterojunction electrode 26 includes a third heterojunction unit and a fourth heterojunction unit connected in series, so that the overall equivalent capacitance of the second heterojunction electrode 2637 can be adjusted within a wider range, and the matching degree between the total equivalent capacitance of the second light-emitting unit 25 and the total equivalent capacitance of the first light-emitting unit 24 can be adjusted to be higher.

[0080] Preferably, the fourth sublayer 261 and the sixth sublayer 263 are n-type conductive layers, and the fifth sublayer 262 is a p-type conductive layer; or, the fourth sublayer 261 and the sixth sublayer 263 are p-type conductive layers, and the fifth sublayer 262 is an n-type conductive layer.

[0081] In this embodiment, the n-type conductive layer in the first heterojunction electrode 22 and / or the second heterojunction electrode 26 is formed by co-evaporation doping with an alkaline earth metal and an electron transport material (ETM). The alkaline earth metal includes, but is not limited to, low work function metals such as lithium (Li), ytterbium (Yb), calcium (Ca), and magnesium (Mg). The thickness of the n-type conductive layer can be from 80 angstroms to 120 angstroms, for example, 100 angstroms.

[0082] In this embodiment, the p-type conductive layer in the first heterojunction electrode 22 and / or the second heterojunction electrode 26 is formed by co-evaporation doping of an organic acceptor material and a hole transport material (HTM). The thickness of the p-type conductive layer can be from 80 angstroms to 120 angstroms, for example, 100 angstroms.

[0083] In one embodiment, reference Figure 7 , Figure 8 , Figure 9 As shown, the number of heterojunction units in the first heterojunction electrode 22 is the same as the number of heterojunction units in the second heterojunction electrode 26.

[0084] In one example, refer to Figure 7 or Figure 9 The first heterojunction electrode 22 adopts a single heterojunction unit structure, which includes a first sublayer 221 and a second sublayer 222. The second heterojunction electrode 26 also adopts a single heterojunction unit structure, which includes a fourth sublayer 261 and a fifth sublayer 262.

[0085] In another example, refer to Figure 8 The first heterojunction electrode 22 adopts a double heterojunction unit structure, which includes two heterojunctions connected in series, consisting of a first sublayer 221, a second sublayer 222, and a third sublayer 223. The second heterojunction electrode 26 also adopts a double heterojunction unit structure, which includes two heterojunctions connected in series, consisting of a fourth sublayer 261, a fifth sublayer 262, and a sixth sublayer 263.

[0086] Similarly, in other examples, when the first heterojunction electrode 22 includes a greater number of heterojunction units, the second heterojunction electrode 26 also maintains the same number of heterojunction units.

[0087] In a stacked OLED device, the first light-emitting unit 24 and the second light-emitting unit 25 are located on opposite sides of the charge generation layer 23, exhibiting symmetrical electrical characteristics. In this embodiment, the first heterojunction electrode 22 and the second heterojunction electrode 26 are designed to have the same number of heterojunction units. On one hand, this achieves structural symmetry between the first light-emitting unit 24 and the second light-emitting unit 25, making them more consistent in their working mechanism, carrier transport path, and transient response characteristics, thus mitigating the performance differences caused by structural asymmetry. On the other hand, when the first heterojunction electrode 22 and the second heterojunction electrode 26 have the same number of heterojunction units, adjusting the first heterojunction electrode 22 and / or the second heterojunction electrode 26 to better match the equivalent capacitance of the first light-emitting unit 24 and the second light-emitting unit 25 allows for the selection of similar material systems and the use of similar thickness ratios, thereby simplifying the complexity of capacitance matching adjustments.

[0088] In one embodiment, each heterojunction unit includes two sub-layers with opposite conductivity types. The sub-layer in the first heterojunction electrode 22 that contacts the first light-emitting unit 24 has a first conductivity type, and the sub-layer in the second heterojunction electrode 26 that contacts the second light-emitting unit 25 has a second conductivity type. The first conductivity type and the second conductivity type are different.

[0089] For example, both the first heterojunction electrode 22 and the second heterojunction electrode 26 are single heterojunction units. The second sublayer 222 of the first heterojunction electrode 22 contacts the first light-emitting unit 24, and the second sublayer 222 has a first conductivity type. The fourth sublayer 261 of the second heterojunction electrode 26 also has a first conductivity type. Alternatively, both the first heterojunction electrode 22 and the second heterojunction electrode 26 are double heterojunction units. The third sublayer 223 of the first heterojunction electrode 22 contacts the first light-emitting unit 24, and the third sublayer 223 has a first conductivity type. The fourth sublayer 261 of the second heterojunction electrode 26 also has a first conductivity type. The first conductivity type is different from the second conductivity type; that is, if the first conductivity type is p-type, then the second conductivity type is n-type; if the first conductivity type is n-type, then the second conductivity type is p-type.

[0090] In this embodiment, the sublayer in the first heterojunction electrode 22 that contacts the first light-emitting unit 24 is p-type, and the sublayer in the second heterojunction electrode 26 that contacts the second light-emitting unit 25 is n-type. That is, the second sublayer 222 or the third sublayer 223 of the first heterojunction electrode 22 is p-type, and the fourth sublayer 261 of the second heterojunction electrode 26 is n-type.

[0091] In a multilayer OLED device, carrier transport is directional. For the first light-emitting unit 24, holes enter the first light-emitting unit 24 from the first electrode 21 via the first heterojunction electrode 22. Therefore, the sublayer in the first heterojunction electrode 22 that contacts the first light-emitting unit 24 should have p-type conductivity to achieve efficient hole injection into the first light-emitting unit 24.

[0092] For the second light-emitting unit 25, electrons enter the second light-emitting unit 25 from the second electrode 27 through the second heterojunction electrode 26. Therefore, the sublayer in the second heterojunction electrode 26 that is in direct contact with the second light-emitting unit 25 should have n-type conductivity characteristics in order to achieve efficient injection of electrons into the second light-emitting unit 25.

[0093] In one embodiment, reference Figure 6 , Figure 7 , Figure 8 As shown, the first light-emitting unit 24 includes a first hole transport layer 241, a first light-emitting functional layer 242 and a first electron transport layer 243, which are sequentially stacked on the first heterojunction electrode 22.

[0094] Reference Figure 6 , Figure 7 , Figure 8 As shown, the second light-emitting unit 25 includes a second hole transport layer, a second light-emitting functional layer and a second electron transport layer sequentially stacked on the charge generation layer 23.

[0095] Reference Figure 6 , Figure 7 , Figure 8 As shown, the charge generation layer 23 includes a first charge generation sublayer 231 and a second charge generation sublayer 232 stacked between the first light-emitting unit 24 and the second light-emitting unit 25. The first charge generation sublayer 231 is close to the first light-emitting unit 24 and is an N-type charge generation layer 23 (N-CGL). The first charge generation sublayer 231 can be made of an electron transport material doped with alkaline earth metals (such as Yb, Li) or an inorganic material (such as zinc oxide). The second charge generation sublayer 232 is close to the second light-emitting unit 25 and is a P-type charge generation layer 23 (P-CGL). The first charge generation sublayer 231 can be made of materials such as molybdenum oxide.

[0096] A PN junction structure is formed at the interface between the first charge-generating sublayer 231 and the second charge-generating sublayer 232, generating electrons and holes under the influence of an electric field. The first charge-generating sublayer 231 injects electrons into the first electron transport layer 243 of the first light-emitting unit 24, and the second charge-generating sublayer 232 injects holes into the second hole transport layer of the second light-emitting unit 25, thereby realizing the series connection of the first light-emitting unit 24 and the second light-emitting unit 25.

[0097] In this process, the first charge generation sublayer 231 injects electrons into the first electron transport layer 243 of the first light-emitting unit 24, and the electrons are transported to the first light-emitting functional layer 242 through the first electron transport layer 243. The first electrode 21 transports holes to the first light-emitting functional layer 242 through the first heterojunction electrode 22 and the first hole transport layer 241. Electrons and holes recombine in the first light-emitting functional layer 242, and the first light-emitting functional layer 242 emits light.

[0098] The second charge-generating sublayer 232 injects holes into the second hole transport layer of the second light-emitting unit 25, realizing the series connection of the first light-emitting unit 24 and the second light-emitting unit 25. The second electrode 27 transports holes through the second electron transport layer to the second light-emitting functional layer, where electrons and holes recombine, and the second light-emitting functional layer emits light.

[0099] Preferably, refer to Figure 9 As shown, the first heterojunction electrode 22 is reused as the first hole transport layer 241 of the first light-emitting unit 24; the top sublayer of the first heterojunction electrode 22 is in direct contact with the first light-emitting functional layer 242.

[0100] In this way, the independent first hole transport layer 241 is reduced, the total thickness of the light-emitting device 20 is reduced, and the driving voltage of the light-emitting device 20 is reduced. The first heterojunction electrode 22 is in direct contact with the first hole transport layer 241, and the holes generated by the first electrode 21 are directly transported to the first hole transport layer 241 through the first heterojunction electrode 22, which improves the carrier transport efficiency and reduces hole transport loss.

[0101] Preferably, refer to Figure 9 As shown, the second heterojunction electrode 26 is reused as the second electron transport layer of the second light-emitting unit 25; the fourth sublayer 261 of the second heterojunction electrode 26 is in direct contact with the second light-emitting functional layer.

[0102] In this way, the independent first electron transport layer 243 is reduced, the total thickness of the light-emitting device 20 is reduced, and the driving voltage of the light-emitting device 20 is reduced. The second heterojunction electrode 26 is in direct contact with the second electron transport layer, and the electrons generated by the second electrode 27 are directly transported to the second electron transport layer through the second heterojunction electrode 26, which improves the carrier transport efficiency and reduces electron transport loss.

[0103] Secondly, this embodiment provides a method for manufacturing a display panel, referring to... Figure 10 As shown, the method for manufacturing the display panel in this embodiment includes the following steps:

[0104] Step S101: Provide substrate 11; refer to Figure 3The substrate 11 can be flexible polyimide (PI), rigid glass, or thin metal sheet, etc.

[0105] Step S102: Form a first electrode 21 on the substrate 11. In this embodiment, refer to... Figure 3 The first electrode 21 material layer can be deposited on the entire surface of the substrate 11 using methods such as magnetron sputtering, thermal evaporation, or ion plating. Then, the first electrode 21 material layer is patterned into multiple independent first electrodes 21 by photolithography.

[0106] Step S103: A pixel defining layer 12 is formed on the substrate 11, and the pixel defining layer 12 is patterned to form a plurality of pixel openings 12a, with at least one pixel opening 12a exposing a portion of the surface of at least one first electrode 21. In this embodiment, reference is made to... Figure 3 A pixel defining layer 12 is formed by methods such as plasma-enhanced chemical vapor deposition (PECVD) or atomic layer deposition (ALD). The pixel defining layer 12 covers a plurality of first electrodes 21. Then, the pixel defining layer 12 is etched to form a plurality of pixel openings 12a. The pixel openings 12a penetrate the pixel defining layer 12 and expose a portion of the first electrode 21 in the central region corresponding to each first electrode 21.

[0107] Step S104: Sequentially deposit at least two sub-layers of opposite conductivity types to form a first heterojunction electrode 22. The first heterojunction electrode 22 covers the first electrode 21 exposed in the pixel opening 12a and extends to the pixel defining layer 12 on the sidewall of the pixel opening 12a.

[0108] In one example, refer to Figure 3 , Figure 6 , Figure 7 , Figure 9 As shown, a first sublayer 221 can be formed by co-evaporation doping of an alkaline earth metal and an electron transport material (ETM). The thickness of the first sublayer 221 is 80 to 120 angstroms, for example, 100 angstroms. The first sublayer 221 is an n-type conductive layer. Then, a second sublayer 222 can be formed by co-evaporation doping of an organic acceptor material and a hole transport material (HTM). The thickness of the second sublayer 222 is 80 to 120 angstroms, for example, 100 angstroms. The second sublayer 222 is a p-type conductive layer. The first heterojunction electrode 22 includes a single heterojunction unit formed by the first sublayer 221 and the second sublayer 222.

[0109] In another example, refer to Figure 3 , Figure 8As shown, a first sublayer 221, a second sublayer 222, and a third sublayer 223 can be formed sequentially. The first sublayer 221 and the third sublayer 223 are formed by co-evaporation doping of organic acceptor materials and hole transport materials (HTM), and the first sublayer 221 and the third sublayer 223 are p-type conductive layers. The second sublayer 222 is formed by co-evaporation doping of alkaline earth metals and electron transport materials (ETM), and the second sublayer 222 is an n-type conductive layer.

[0110] Step S105: A first light-emitting unit 24, a charge-generating layer 23, a second light-emitting unit 25, and a second electrode 27 are sequentially formed in the pixel opening 12a. The first light-emitting unit 24, the charge-generating layer 23, the second light-emitting unit 25, and the second electrode 27 are sequentially stacked on the first heterojunction electrode 22.

[0111] In this embodiment, refer to Figure 3 , Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown, the steps for forming the first light-emitting unit 24 include: sequentially depositing a first hole transport layer 241, a first light-emitting functional layer 242, and a first electron transport layer 243 on the first heterojunction electrode 22. The first light-emitting functional layer 242 is deposited using a fine metal mask (FMM) or an open mask, so that the first light-emitting functional layer 242 in each pixel opening 12a is disconnected.

[0112] In this embodiment, refer to Figure 3 , Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown, a first charge generation sublayer 231 and a second charge generation sublayer 232 are sequentially deposited on the first electron transport layer 243 to form a charge generation layer 23. The first charge generation sublayer 231 is an N-type charge generation layer 23; the second charge generation sublayer 232 is a P-type charge generation layer 23.

[0113] In this embodiment, refer to Figure 3 , Figure 6 , Figure 7 , Figure 8 , Figure 9 As shown, the step of forming the second light-emitting unit 25 includes: sequentially depositing a second hole transport layer, a second light-emitting functional layer, and a second electron transport layer on the charge generation layer 23. The second light-emitting functional layer is deposited using a fine metal mask (FMM) or an open mask, so that the second light-emitting functional layer in each pixel opening 12a is disconnected.

[0114] In this embodiment, a semi-transparent or transparent conductive material, such as a magnesium-silver alloy or a combination thereof, is used to form the second electrode 27 by thermal evaporation or sputtering. The second electrode 27 is formed by full-surface vapor deposition and extends to the upper surface of the pixel defining layer 12.

[0115] The method for manufacturing the display panel in this embodiment involves forming a first heterojunction electrode 22 between the first electrode 21 and the first light-emitting unit 24. The equivalent capacitance of the first light-emitting unit 24 includes the capacitance formed by the first heterojunction electrode 22 and the charge generation layer 23. The equivalent capacitance of the first light-emitting unit 24 can be adjusted by adjusting the first heterojunction electrode 22 (material selection, doping concentration, thickness, and coverage area), thereby adjusting the equivalent capacitance of the first light-emitting unit 24 to match the capacitance of the second light-emitting unit 25. When switching between low grayscale images, the transient overshoot during voltage switching can be improved or even eliminated, the brightness flicker during low grayscale image switching can be improved, the display effect can be enhanced, and the user experience can be optimized.

[0116] In one embodiment, after the formation of the second light-emitting unit 25 and before the formation of the second electrode 27, step S105-1 is performed: at least two sub-layers of opposite conductivity types are deposited sequentially to form the second heterojunction electrode 26.

[0117] Reference Figure 7 , Figure 8 , Figure 9 As shown, at least two fourth sublayers 261 and 262 with opposite conductivity types can be sequentially deposited on the second light-emitting unit 25 to form a second heterojunction electrode 26 including a single heterojunction unit. Alternatively, a fourth sublayer 261, a fifth sublayer 262, and a sixth sublayer 263 can be sequentially deposited on the second light-emitting unit 25 to form a second heterojunction electrode 26 including a double heterojunction unit. The deposition method and material selection of the second heterojunction electrode 26 are similar to those of the first heterojunction electrode 22, but the order of its conductivity types can be optimized according to the electron injection requirements, for example, using an n / p / n three-layer structure. Subsequently, a second electrode 27 is formed on the second heterojunction electrode 26.

[0118] In one embodiment, reference Figure 9 As shown, the uppermost sublayer (second sublayer 222 or third sublayer 223) of the first heterojunction electrode 22 formed in step S104 also has hole transport function. Therefore, when the first light-emitting unit 24 is formed in step S105, the evaporation step of forming the first hole transport layer 241 can be omitted, and the first light-emitting functional layer 242 can be directly deposited on the first heterojunction electrode 22. The first heterojunction electrode 22 is reused as the first hole transport layer 241.

[0119] In one embodiment, reference Figure 9As shown, the fourth sub-layer 261 of the second heterojunction electrode 26 formed in step S104 also has an electron transport function. When forming the second light-emitting unit 25, the evaporation step of forming the second electron transport layer can be omitted, and the second heterojunction electrode 26 can be directly evaporated on the second light-emitting functional layer. The second heterojunction electrode 26 is reused as the second electron transport layer.

[0120] The method for manufacturing the display panel in this embodiment can adjust the equivalent capacitance of the first light-emitting unit 24 by adjusting the first heterojunction electrode 22 and the equivalent capacitance of the second light-emitting unit 25 by adjusting the second heterojunction electrode 26, so that the equivalent capacitance of the first light-emitting unit 24 and the equivalent capacitance of the second light-emitting unit 25 are matched. This can effectively suppress the transient brightness overshoot phenomenon when switching low grayscale images, thereby improving the display effect of the display panel 100.

[0121] It should be understood that, although Figure 10 The steps in the process described above are shown sequentially according to arrows or the order indicated by the arrows; however, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise explicitly stated herein, there is no strict order requirement for the execution of these steps, and they can be executed in other orders. Furthermore, Figure 11 At least some of the steps in the process described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0122] Thirdly, such as Figure 11 As shown, this application provides a display device 1, which includes a display panel 100 as described in the first aspect embodiment, or a display panel 100 manufactured by the method of manufacturing a display panel as described in the second aspect embodiment.

[0123] Display device 1 can be a portable electronic device such as a mobile phone, smartphone, tablet PC, mobile communication terminal, e-notebook, e-reader, portable multimedia player (PMP), navigation device, and ultra-mobile PC (UMPC). In embodiments, for example, display device 1 can be a display unit of a television, laptop computer, monitor, billboard, or Internet of Things (IoT) device. In embodiments, for example, display device 1 can be a wearable device such as a smartwatch, watch phone, glasses display, and head-mounted display (HMD).

[0124] The display device 1 can be formed into a planar shape similar to a polygon. In one embodiment, for example, the display device 1 can have a planar shape similar to a polygon, the polygon having a short side in the second direction Y and a long side in the first direction X. In one embodiment, the display device 1 can have a planar shape similar to a polygon, the polygon having a long side in the second direction Y and a short side in the first direction X intersecting the second direction Y. The angle where the short and long sides meet can be formed as a circle with a predetermined curvature or as a right angle. In embodiments, the planar shape of the display device 1 is not limited to a polygon, and can be formed similar to other polygons, circles, or ellipses.

[0125] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A display panel, characterized in that, include: substrate; A pixel defining layer is disposed on one side of the substrate, and the pixel defining layer includes a plurality of pixel openings; At least one light-emitting device is disposed in at least one of the pixel openings, and the light-emitting device includes a first electrode, a first heterojunction electrode, a first light-emitting unit, a charge-generating layer, a second light-emitting unit, and a second electrode stacked in sequence. The first heterojunction electrode includes at least one heterojunction unit stacked between the first electrode and the first light-emitting unit.

2. The display panel according to claim 1, characterized in that, The first electrode is disposed on the substrate, the pixel defining layer covers the end of the first electrode, and the pixel opening exposes a portion of the first electrode; The first heterojunction electrode covers the first electrode exposed by the pixel opening and extends to the pixel defining layer on the sidewall of the pixel opening; Preferably, the first heterojunction electrode further extends to the top surface of the pixel defining layer on the side opposite to the substrate.

3. The display panel according to claim 1, characterized in that, The first heterojunction electrode includes at least a first sub-layer and a second sub-layer stacked between the first electrode and the first light-emitting unit. The first sub-layer and the second sub-layer have opposite conductivity types, forming a first heterojunction unit. Preferably, the first heterojunction electrode further includes a third sublayer, which is disposed between the second sublayer and the first light-emitting unit; the third sublayer has the opposite conductivity type to the second sublayer, forming a second heterojunction unit; Preferably, the first sub-layer and the third sub-layer are n-type conductive layers, and the second sub-layer is a p-type conductive layer; or, the first sub-layer and the third sub-layer are p-type conductive layers, and the second sub-layer is an n-type conductive layer.

4. The display panel according to any one of claims 1-3, characterized in that, The light-emitting device further includes: A second heterojunction electrode is disposed between the second light-emitting unit and the second electrode, and the second heterojunction electrode includes at least one heterojunction unit stacked between the second light-emitting unit and the second electrode.

5. The display panel according to claim 4, characterized in that, The second heterojunction electrode includes at least a fourth sub-layer and a fifth sub-layer stacked between the second light-emitting unit and the second electrode, wherein the fourth sub-layer and the fifth sub-layer have opposite conductivity types, forming a third heterojunction unit; Preferably, the second heterojunction electrode further includes a sixth sublayer, which is disposed between the fifth sublayer and the second electrode; the sixth sublayer has the opposite conductivity type to the fifth sublayer, forming a fourth heterojunction unit; Preferably, the fourth sub-layer and the sixth sub-layer are n-type conductive layers, and the fifth sub-layer is a p-type conductive layer; or, the fourth sub-layer and the sixth sub-layer are p-type conductive layers, and the fifth sub-layer is an n-type conductive layer.

6. The display panel according to claim 5, characterized in that, The number of heterojunction units in the first heterojunction electrode is the same as the number of heterojunction units in the second heterojunction electrode.

7. The display panel according to claim 4, characterized in that, Each heterojunction unit includes two sub-layers with opposite conductivity types. The sub-layer in the first heterojunction electrode that contacts the first light-emitting unit has a first conductivity type, and the sub-layer in the second heterojunction electrode that contacts the second light-emitting unit has a second conductivity type. The first conductivity type and the second conductivity type are different.

8. The display panel according to claim 1, characterized in that, The first light-emitting unit includes a first hole transport layer, a first light-emitting functional layer, and a first electron transport layer sequentially stacked on the first heterojunction electrode; The second light-emitting unit includes a second hole transport layer, a second light-emitting functional layer, and a second electron transport layer, which are sequentially stacked on the charge generation layer; The charge generation layer includes a first charge generation sublayer and a second charge generation sublayer stacked between the first light-emitting unit and the second light-emitting unit; Preferably, the first heterojunction electrode is reused as the first hole transport layer of the first light-emitting unit; Preferably, the second heterojunction electrode is reused as the second electron transport layer of the second light-emitting unit.

9. A method for manufacturing a display panel, characterized in that, Includes the following steps: Provide substrate; A first electrode is formed on the substrate; A pixel defining layer is formed on the substrate, and the pixel defining layer is patterned to form a plurality of pixel openings, at least one of the pixel openings exposing a portion of the surface of at least one first electrode; At least two sublayers of opposite conductivity types are sequentially deposited to form a first heterojunction electrode, which covers the first electrode exposed by the pixel opening and extends to the pixel defining layer on the sidewall of the pixel opening. A first light-emitting unit, a charge-generating layer, a second light-emitting unit, and a second electrode are sequentially formed in the pixel opening. The first light-emitting unit, the charge-generating layer, the second light-emitting unit, and the second electrode are sequentially stacked on the first heterojunction electrode.

10. A display device, characterized in that, Includes the display panel as described in any one of claims 1-8.

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