Light emitting device and display panel

Abstract

This disclosure discloses a light-emitting device and a display panel, relating to the field of display technology, to address the problem of low light extraction efficiency in light-emitting devices. The light-emitting device comprises a first electrode, at least two light-emitting units, and a second electrode stacked sequentially along a first direction. The at least two light-emitting units include a first light-emitting unit, a second light-emitting unit located between the first light-emitting unit and the second electrode, and a charge-generating layer located between the first and second light-emitting units. The first light-emitting unit includes a first light-emitting layer. In the light-emitting device, among a plurality of film layers located on the side of the first light-emitting layer away from the first electrode, two adjacent film layers include at least three metals, and the absolute value of the work function of at least two metals is greater than 3.5 eV, while the absolute value of the work function of at least one metal is less than 3.5 eV. The light-emitting device and display panel provided by this disclosure can reduce the driving voltage of the light-emitting device.

Description

[0001] This disclosure is a divisional application. The original application has the application number 202210789887.1 and the original application date is July 6, 2022. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of display technology, and more particularly to a light-emitting device and a display panel. Background Technology

[0003] Organic light-emitting diodes (OLEDs) have gained attention from enterprises and universities and have developed rapidly due to their many advantages, such as self-illumination, high brightness, high contrast, fast response speed, wide viewing angle, simple structure and flexible display.

[0004] Therefore, tandem organic light-emitting diodes (TOLEDs) emerged in the development of OLEDs. Tandem OLEDs have the advantage of high brightness. However, Tandem OLEDs in related technologies suffer from the problem of high driving voltage. Summary of the Invention

[0005] The purpose of this disclosure is to provide a light-emitting device and a display panel for reducing the driving voltage of a TandemOLED.

[0006] To achieve the above objectives, some embodiments of this disclosure provide the following technical solutions:

[0007] On one hand, a light-emitting device is provided. The light-emitting device includes a first electrode, at least two light-emitting units, and a second electrode stacked sequentially along a first direction. The at least two light-emitting units include a first light-emitting unit, a second light-emitting unit located between the first light-emitting unit and the second electrode, and a charge-generating layer located between the first light-emitting unit and the second light-emitting unit. The first light-emitting unit includes a first light-emitting layer. In the light-emitting device, among a plurality of film layers located on the side of the first light-emitting layer away from the first electrode, two adjacent film layers include at least three metals, and the absolute value of the work function of at least two metals is greater than 3.5 eV, while the absolute value of the work function of at least one metal is less than 3.5 eV.

[0008] In the light-emitting device provided in this embodiment, by arranging at least three metals in the adjacent film layers located on the side of the first light-emitting layer away from the first electrode, the coordination relationship between the work functions of different metals inside the light-emitting device can be increased, the overall electron injection capability of the light-emitting device can be improved, thereby improving the light extraction efficiency of the light-emitting device and reducing the driving voltage required by the light-emitting device.

[0009] In some embodiments, one of the two adjacent membrane layers comprises at least three metals.

[0010] In some embodiments, one of the two adjacent membrane layers comprises at least two metals, wherein the absolute value of the work function of at least one metal is greater than 3.5 eV and the absolute value of the work function of at least one metal is less than 3.5 eV.

[0011] In some embodiments, the two adjacent films comprise the same metal, and the absolute value of the work function of the same metal is less than 3.5 eV.

[0012] In some embodiments, the two adjacent films comprise different metals, and both adjacent films comprise a metal with an absolute work function of less than 3.5 eV.

[0013] In some embodiments, the second light-emitting unit includes a second light-emitting layer and a second electron injection layer located between the second light-emitting layer and the second electrode. The two adjacent film layers include the second electron injection layer and the second electrode.

[0014] In some embodiments, the charge generation layer includes a first charge generation sublayer and a second charge generation sublayer; the first charge generation sublayer is located between the first light-emitting unit and the second charge generation sublayer. The first charge generation sublayer includes at least one metal, and the absolute value of the work function of the metal in the first charge generation sublayer is less than 3.5 eV.

[0015] In some embodiments, the second light-emitting unit includes a second light-emitting layer and a second electron transport layer located between the second light-emitting layer and the second electrode. The second electron transport layer and the charge-generating layer are made of the same metal.

[0016] In some embodiments, the film layer farther from the first electrode among the two adjacent film layers includes at least one of silver, aluminum, gold, copper, magnesium, molybdenum, and tin. The film layer closer to the first electrode among the two adjacent film layers includes at least one of lithium, ytterbium, cesium, and calcium.

[0017] In another aspect, a light-emitting device is provided. This light-emitting device includes a first electrode, at least two light-emitting units, and a second electrode stacked sequentially along a first direction. The at least two light-emitting units include a first light-emitting unit, a second light-emitting unit located between the first light-emitting unit and the second electrode, and a charge-generating layer located between the first light-emitting unit and the second light-emitting unit. The first light-emitting unit includes a first light-emitting layer. Each of the first, second, and third films located on the side of the first light-emitting layer away from the first electrode includes at least one metal, collectively including at least three metals. The distances of the first, second, and third films from the first electrode increase sequentially, and the second and third films are arranged adjacent to each other. The absolute value of the work function of at least one metal in the third film is greater than the absolute value of the work function of at least one metal in the second film; the absolute value of the work function of at least one metal in the third film is greater than the absolute value of the work function of at least one metal in the first film.

[0018] In the light-emitting device provided in this embodiment, by making the absolute value of the work function of at least one metal in the third film layer greater than the absolute value of the work function of at least one metal in the second film layer and the absolute value of the work function of at least one metal in the first film layer, the coordination relationship between the work functions of different metals inside the light-emitting device can be increased, the overall electron injection capability of the light-emitting device can be improved, thereby improving the light extraction efficiency of the light-emitting device and reducing the driving voltage required by the light-emitting device.

[0019] In some embodiments, the third film layer comprises at least two metals; the absolute value of the work function of each metal in the third film layer is not less than the absolute value of the metal in the second film layer.

[0020] In some embodiments, the first film layer, the second film layer, and the third film layer comprise the same metal. The absolute value of the work function of the same metal is less than 3.5 eV.

[0021] In some embodiments, the second light-emitting unit includes a second light-emitting layer; the first film layer is located on the side of the second light-emitting layer closer to the first electrode; the second film layer and the third film layer are located on the side of the second light-emitting layer away from the first electrode.

[0022] In some embodiments, the absolute value of the work function of the metal in the first film layer is less than 3.5 eV, and the proportion of the volume of the metal in the first film layer to the volume of the first film layer is less than or equal to 1%.

[0023] In another aspect, a display panel is provided, including a pixel defining layer and a light-emitting device. The pixel defining layer has a plurality of light-emitting openings. The light-emitting device is the light-emitting device as described in any of the above embodiments, and is located within the plurality of light-emitting openings.

[0024] The display panel provided in this disclosure includes the aforementioned light-emitting device. Therefore, the beneficial effects that the display panel provided in this disclosure can achieve include at least the same beneficial effects as those of the light-emitting device provided in the above-described technical solutions, which will not be elaborated here. Attached Figure Description

[0025] 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.

[0026] Figure 1 A perspective view of a display panel according to some embodiments;

[0027] Figure 2 According to Figure 1 A cross-sectional view of the display panel along line A-A' in the illustrated embodiment;

[0028] Figures 3-7 This is a diagram showing the arrangement of subpixels in a display panel according to some embodiments;

[0029] Figure 8 This is a cross-sectional view of a display panel according to some embodiments;

[0030] Figure 9 for Figure 2 Enlarged views of regions FD1, FD2, and FD3 in some embodiments;

[0031] Figure 10 for Figure 2 Enlarged views of regions FD1, FD2, and FD3 in some embodiments;

[0032] Figure 11 for Figure 2 Enlarged views of regions FD1, FD2, and FD3 in some embodiments;

[0033] Figure 12 This is a structural diagram of a light-emitting device in a display panel according to some embodiments;

[0034] Figure 13 for Figure 8Enlarged views of regions FD1, FD2, and FD3 in some embodiments;

[0035] Figure 14 This is a current density curve of the second electrode under different driving voltages in different schemes of a display panel according to some embodiments. Detailed Implementation

[0036] 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.

[0037] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is 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 embodiment," "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 feature, structure, material, or characteristic may be included in any suitable manner in any one or more embodiments or examples.

[0038] 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.

[0039] The term "electrical connection" is used in describing some embodiments. For example, the term "electrical connection" is used in describing some embodiments to indicate that two or more components are in electrical contact with each other.

[0040] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0041] 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.

[0042] As used herein, “approximately” includes the values ​​stated and the average value within an acceptable range of deviation from the given values, 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).

[0043] In this article, "the ratio between C and D" can refer to the ratio between the volume of C and the volume of D.

[0044] 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 regions is 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 limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched regions 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 regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0045] With the rapid development of OLED display panels, Tandem OLED display panels have become an important development direction for OLED display technology. Tandem OLED is composed of two or more layers of light-emitting units stacked together, with a charge generation layer introduced between the two light-emitting units, thereby achieving the effect of simultaneous light emission from both the upper and lower light-emitting units, thus having the advantage of high brightness.

[0046] However, the inventors of this publication have discovered that, due to the relatively thick stacked structure of Tandem OLEDs, the organic layer has limited charge transport capability, which restricts electron injection and transport to a certain extent, resulting in a problem of high overall driving voltage for the light-emitting device.

[0047] Based on this, some embodiments of the present disclosure provide a light-emitting device and a display panel, which are described below.

[0048] Figure 1 This is a perspective view of a display panel according to some embodiments. Figure 2 According to Figure 1 The illustrated embodiment shows a cross-sectional view of the display panel along line A-A'. Figure 1As shown, the display panel 100 includes a display area AA for displaying images and a non-display area SA for not displaying images. The non-display area SA surrounds at least one side of the display area AA (e.g., one side; or, all around, including the top and bottom sides and the left and right sides). In some examples, the non-display area SA may completely enclose the display area AA and may be located outside the display area AA in at least one direction. The display panel 100 described above may have a rectangular shape in a plan view, or it may have a circular, elliptical, rhomboid, trapezoidal, square, or other shapes depending on the display requirements.

[0049] The aforementioned display panel 100 can be applied to display devices. For example, the display device can be a small to medium-sized electronic device such as a tablet computer, smartphone, head-mounted display, car navigation unit, camera, center information display (CID) provided in a vehicle, watch-type electronic device or other wearable device, personal digital assistant (PDA), portable multimedia player (PMP), and game console; as well as medium to large-sized electronic devices such as televisions, external billboards, monitors, home appliances containing display screens, personal computers, and laptop computers. The electronic devices described above represent only simple examples of applications for display devices, and therefore those skilled in the art will recognize that other electronic devices can also be used without departing from the spirit and scope of this disclosure.

[0050] Combination Figure 1 , Figure 2 and Figure 8 As shown, some embodiments of this disclosure provide a display panel 100. The display panel 100 includes a substrate SUB, a light-emitting device layer LDL, a light extraction layer CPL, and an encapsulation layer TFE.

[0051] The substrate SUB includes a plurality of repeating pixel unit regions PU. Each pixel unit region PU may include a first sub-pixel region P1, a second sub-pixel region P2, and a third sub-pixel region P3 that display different colors. For example, the first sub-pixel region P1 is configured to display red light, the second sub-pixel region P2 is configured to display green light, and the third sub-pixel region P3 is configured to display blue light.

[0052] In addition, the pixel unit area PU may also include a non-light-emitting area P4. The non-light-emitting area P4 may be located between the first sub-pixel area P1 and the second sub-pixel area P2, between the second sub-pixel area P2 and the third sub-pixel area P3, and between the third sub-pixel area P3 and the first sub-pixel area P1.

[0053] In some examples, such as Figures 3-5As shown, a pixel unit area PU includes a first sub-pixel area P1, a second sub-pixel area P2, and a third sub-pixel area P3. The first sub-pixel area P1, the second sub-pixel area P2, and the third sub-pixel area P3 can be arranged alternately and repeatedly along the second direction Y within the display area AA.

[0054] In some examples, such as Figure 6 and Figure 7 As shown, a pixel unit area PU can include two sub-pixel areas displaying the same color, and these two sub-pixel areas can be arranged adjacent to each other. For example, a pixel unit area PU includes one red sub-pixel area R, two green sub-pixel areas G, and one blue sub-pixel area B, wherein the two green sub-pixel areas G within a pixel unit area PU can be arranged adjacent to each other.

[0055] In some examples, a pixel unit area PU includes a first sub-pixel area P1, two second sub-pixel areas P2, and a third sub-pixel area P3. The first sub-pixel area P1, the two second sub-pixel areas P2, and the third sub-pixel area P3 can be arranged alternately and repeatedly along the second direction Y within the display area AA. In this case, a non-light-emitting area P4 can also be located between the two second sub-pixel areas P2.

[0056] like Figure 2 As shown, within a pixel unit region PU, in the second direction (parallel to the substrate SUB) Y, the first sub-pixel region P1 has a first width WL1, the second sub-pixel region P2 has a second width WL2, and the third sub-pixel region P3 has a third width WL3. The first width WL1, the second width WL2, and the third width WL3 can be different from each other.

[0057] like Figure 8 As shown, the display panel 100 may include multiple pixel circuits located on the substrate SUB. A pixel unit region PU may include a first pixel circuit S1, a second pixel circuit S2, and a third pixel circuit S3. For example, the first pixel circuit S1 is located in a first sub-pixel region P1, the second pixel circuit S2 is located in a second sub-pixel region P2, and the third pixel circuit S3 is located in a third sub-pixel region P3. As another example, at least one of the first pixel circuit S1, the second pixel circuit S2, and the third pixel circuit S3 may have a thin-film transistor located in a non-light-emitting region P4.

[0058] The structure of a pixel circuit can be varied and can be selected according to actual needs. For example, a pixel circuit may include at least two transistors (denoted by T) and at least one capacitor (denoted by C). For instance, the pixel circuit S may have a structure such as "2T1C", "6T1C", "7T1C", "6T2C" or "7T2C".

[0059] At least one of the first pixel circuit S1, the second pixel circuit S2, and the third pixel circuit S3 may be a thin-film transistor comprising polysilicon or an oxide semiconductor. For example, when the thin-film transistor is an oxide semiconductor thin-film transistor, it may have a top-gate thin-film transistor structure. The thin-film transistor may be connected to signal lines, including but not limited to gate lines, data lines, and power lines.

[0060] like Figure 8 As shown, the display panel 100 may include an insulating layer INL, which may be located on the first pixel circuit S1, the second pixel circuit S2, and the third pixel circuit S3. The insulating layer INL may have a planarized surface. The insulating layer INL may be formed of an organic layer. For example, the insulating layer INL may include acrylic resin, epoxy resin, imide resin, or ester resin, etc. The insulating layer INL may have through holes to expose the electrodes of the first pixel circuit S1, the second pixel circuit S2, and the third pixel circuit S3 for electrical connection.

[0061] Combination Figure 2 and Figure 8 As shown, the display panel 100 may include a light-emitting device layer (LDL) and a pixel-defining layer (PDL) located on a substrate SUB. The PDL may be formed on an insulating layer INL and define multiple light-emitting openings. For example, the PDL may include a first light-emitting opening K1 located in a first sub-pixel region P1, a second light-emitting opening K2 located in a second sub-pixel region P2, and a third light-emitting opening K3 located in a third sub-pixel region P3. The LDL has multiple light-emitting devices connected to the pixel circuit S, each located within a plurality of light-emitting openings. Within a pixel unit region PU, the light-emitting devices include a first light-emitting device LD1, a second light-emitting device LD2, and a third light-emitting device LD3. For example, the first light-emitting device LD1 may be located in the first light-emitting opening K1, the second light-emitting device LD2 may be located in the second light-emitting opening K2, and the third light-emitting device LD3 may be located in the third light-emitting opening K3.

[0062] The light-emitting device may include a first electrode, at least two light-emitting units 200, and a second electrode CE, which are stacked sequentially along a first direction (i.e., a direction perpendicular to the substrate SUB).

[0063] In some examples, the display panel 100 is a top-emitting display panel. The first electrode is a reflective electrode that can reflect light, such as an anode; the second electrode CE is a transmissive electrode that can transmit light, such as a cathode. In this way, a microcavity structure is formed between the anode and the cathode.

[0064] In other examples, the display panel 100 is a bottom-emitting display panel. The first electrode is a transmissive electrode that transmits light, such as an anode; the second electrode CE is a reflective electrode that reflects light, such as a cathode. In this way, a microcavity structure is formed between the anode and the cathode.

[0065] like Figure 8 and Figure 9 The first electrode includes a first electrode AE1 located in the first sub-pixel region P1, a first electrode AE2 located in the second sub-pixel region P2, and a first electrode AE3 located in the third sub-pixel region P3.

[0066] In some embodiments, the first electrode may comprise a material with a high work function, such as metals or mixtures thereof including Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, or Cr, or a transparent conductive oxide material such as ITO, IZO, or IGZO. The dimensions of the first electrode AE ​​in the first direction X may be in the range of 80 nm to 200 nm.

[0067] In some examples, the display panel 100 is a top-emitting display panel. The first electrode may include a multilayer composite structure such as transparent conductive oxide / metal / transparent conductive oxide. The transparent conductive oxide material is, for example, ITO or IZO, and the metal material is, for example, Au, Ag, Ni, or Pt. For example, the anode structure is ITO / Ag / ITO. The size of the metal in the first direction X can be in the range of 50 nm to 150 nm; the size of the transparent conductive oxide in the first direction X can be in the range of 5 nm to 15 nm. Furthermore, the average reflectivity of the first electrode for visible light can be in the range of 85% to 95%.

[0068] In some examples, the display panel 100 is a bottom-emitting display panel. The first electrode may include a transparent conductive oxide such as ITO, IZO, or IGZO.

[0069] In some embodiments, the second electrode CE may comprise a metallic material or an alloy material. The metallic material may be, for example, Al, Ag, or Mg, and the alloy material may be, for example, a Mg:Ag alloy or an Al:Li alloy. Exemplarily, the cathode comprises a Mg:Ag alloy, wherein the ratio of Mg to Ag elements may be in the range of 3:7 to 1:9.

[0070] In some examples, the display panel 100 is a top-emitting display panel. The size of the second electrode CE in the first direction X can be in the range of 10nm to 20nm. The average transmittance of the second electrode CE to visible light can be greater than or equal to 50%, such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, etc.

[0071] In other examples, the display panel 100 is a bottom-emitting display panel. The size of the second electrode CE in the first direction can be greater than or equal to 80 nm, such as 80 nm, 85 nm, 90 nm, 95 nm, etc. This ensures that the second electrode CE, as a reflective electrode, has good reflectivity to light.

[0072] like Figure 8 and Figure 9 The second electrode CE includes a second electrode CE1 located in the first sub-pixel region P1, a second electrode CE2 located in the second sub-pixel region P2, and a second electrode CE3 located in the third sub-pixel region P3.

[0073] At least two light-emitting units 200 between the first electrode AE ​​and the second electrode CE can be stacked in the first direction X. The number of light-emitting units 200 between the first electrode and the second electrode CE can be two, three, or other numbers, which are not limited here.

[0074] like Figure 2 and Figure 9 As shown, in some examples, a first light-emitting unit 210 and a second light-emitting unit 220 are included between the first electrode and the second electrode CE, that is, two light-emitting units 200 are included between the first electrode and the second electrode CE. The first light-emitting unit 210 can be in direct contact with the first electrode, and the second light-emitting unit 220 is located between the first light-emitting unit 210 and the second electrode CE, and the second light-emitting unit 220 can be in direct contact with the second electrode CE.

[0075] The first light-emitting unit 210 includes a first light-emitting layer (e.g., EL1-1 / EL2-1 / EL3-1), a first transport layer TL1, and a second transport layer TL2. The first transport layer TL1 is located between the first light-emitting layer and the first electrode AE. Understandably, the dimension of the first transport layer TL1 in the first direction X is equal to the distance between the first electrode AE ​​and the first light-emitting layer EL1 in the first direction. The first transport layer TL1 is configured to transport holes from the first electrode AE ​​to the first light-emitting layer. The second transport layer TL2 is located between the first light-emitting layer and the second light-emitting unit 220. Understandably, the dimension of the second transport layer TL2 in the first direction X is equal to the distance between the first light-emitting layer and the second light-emitting unit 220 in the first direction X. The second transport layer TL2 is configured to transport electrons to the first light-emitting layer. Thus, holes and electrons recombine in the first light-emitting layer, causing the first light-emitting layer to emit light.

[0076] The second light-emitting unit 220 includes a second light-emitting layer (e.g., EL1-2 / EL2-2 / EL3-2), a third transport layer TL3, and a fourth transport layer TL4. The third transport layer TL3 is located between the second light-emitting layer and the first light-emitting unit 210. Understandably, the dimension of the third transport layer TL3 in the first direction X is equal to the spacing between the first light-emitting unit 210 and the second light-emitting layer in the first direction X. The third transport layer TL3 is configured to transport holes to the second light-emitting layer. The fourth transport layer TL4 is located between the second light-emitting layer and the second electrode CE. Understandably, the dimension of the fourth transport layer TL4 in the first direction X is equal to the spacing between the second light-emitting layer and the second electrode CE in the first direction X. The fourth transport layer TL4 is configured to transport electrons from the second electrode CE to the second light-emitting layer. Thus, holes and electrons recombine in the second light-emitting layer, causing the second light-emitting layer to emit light.

[0077] like Figure 9 As shown, in some embodiments, the light-emitting device further includes a charge generation layer 300 located between two adjacent light-emitting units 200. Exemplarily, the charge generation layer 300 includes a P-type charge generation sublayer 310 and an N-type charge generation sublayer 320. The N-type charge generation sublayer 320 can directly contact the first light-emitting unit 210, for example, the N-type charge generation sublayer 320 can directly contact the second transport layer TL2, providing electrons to the first light-emitting unit 210. The P-type charge generation sublayer 310 can directly contact the second light-emitting unit 220, for example, the P-type charge generation sublayer 220 can directly contact the third transport layer TL3, providing holes to the second light-emitting unit 220.

[0078] In some examples, the second transport layer TL2 is configured to transport electrons provided by the charge generation layer 300 to the first light-emitting layer, so that holes provided by the first electrode AE ​​and electrons provided by the charge generation layer 300 recombine to emit light in the first light-emitting layer. The third transport layer TL3 is configured to transport holes provided by the charge generation layer 300 to the second light-emitting layer, so that holes provided by the charge generation layer 300 and electrons provided by the second electrode CE recombine to emit light in the second light-emitting layer.

[0079] The charge generation layer 300 may include metals, undoped organic materials, organic PN junctions or metal oxides composed of P-type and N-type doping, etc., which are not limited here.

[0080] In some embodiments, within the same light-emitting device, the absolute value of the difference between the wavelength of light emitted by the first light-emitting layer and the wavelength of light emitted by the second light-emitting layer can be less than or equal to 10 nm. For example, 10 nm, 8 nm, 5 nm, 3 nm, etc.

[0081] Understandably, two light-emitting units 200 within the same light-emitting device emit the same or similar light. This improves the concentration of the spectral superposition of the two light-emitting units 200, thereby increasing the color purity and light extraction efficiency of the light.

[0082] For example, the light-emitting device is a blue light-emitting device. The wavelength of the light emitted by the first light-emitting layer in the blue light-emitting device is 460nm, and the wavelength of the light emitted by the second light-emitting layer in the blue light-emitting device can be 450nm to 470nm. In this way, the light extraction efficiency of the light corresponding to the wavelengths that overlap in the light-emitting device can be improved.

[0083] In some embodiments, within the same light-emitting device, the difference between the wavelength at which the light emitted by the first light-emitting layer reaches its spectral peak and the wavelength at which the light emitted by the second light-emitting layer reaches its spectral peak is less than 5%.

[0084] Understandably, the two types of light emitted by the two light-emitting units 200 within the same light-emitting device have the same or similar wavelengths at their spectral peaks. This improves the concentration of the spectral superposition of the two light-emitting units 200, thereby increasing the color purity and light extraction efficiency of the light.

[0085] For example, the light-emitting device is a red light-emitting device. The light emitted by the first light-emitting layer in the red light-emitting device has a wavelength of 530nm at its spectral peak, while the light emitted by the second light-emitting layer in the red light-emitting device can have a wavelength of 504nm to 557nm at its spectral peak. In this way, the light extraction efficiency of the light corresponding to the wavelengths that overlap in the light-emitting device can be improved.

[0086] like Figure 9 As shown, in some examples, the first transport layer TL1 may include a first hole injection layer HIL1 and a first hole transport layer HTL1. The first hole injection layer HIL1 is located between the first electrode AE ​​and the first hole transport layer HTL1, and is configured to inject holes from the first electrode AE ​​into the first hole transport layer HTL1. The first hole transport layer HTL1 is located between the first hole injection layer HIL1 and the first light-emitting layer, and is configured to transport the holes injected by the first hole injection layer HIL1 to the first light-emitting layer, so that the holes recombine with electrons within the first light-emitting layer, thereby achieving light emission from the first light-emitting layer.

[0087] like Figure 9 As shown, in some examples, the first transport layer TL1 may further include a first exciton blocking layer BL1. The first exciton blocking layer BL1 may be located between the first hole transport layer HTL1 and the first light-emitting layer, and the first exciton blocking layer BL1 is configured to block electrons in the first light-emitting layer from moving toward the first electrode. Therefore, the first exciton blocking layer BL1 may also be referred to as an electron blocking layer EBL.

[0088] like Figures 9 to 11 As shown, in some examples, the second transport layer TL2 may include the first electron transport layer ETL1 and / or the first electron injection layer EIL1.

[0089] For example, such as Figure 10 As shown, the second transport layer TL2 includes only the first electron transport layer ETL1, which is in direct contact with both the first light-emitting layer and the N-type charge generation layer 320. The first electron transport layer ETL1 is configured to transport electrons provided by the N-type charge generation layer 320 to the first light-emitting layer, allowing electrons to recombine with holes within the first light-emitting layer, thereby enabling the first light-emitting layer to emit light.

[0090] For example, such as Figure 11 As shown, the second transport layer TL2 includes only the first electron injection layer EIL1, which is in direct contact with both the first light-emitting layer and the N-type charge generation layer 320. The first electron injection layer EIL1 is configured to inject electrons provided by the N-type charge generation sublayer into the first light-emitting layer, causing electrons to recombine with holes within the first light-emitting layer, thereby enabling the first light-emitting layer to emit light.

[0091] For example, such as Figure 9 As shown, the second transport layer TL2 includes a first electron transport layer ETL1 and a first electron injection layer EIL1. The first electron injection layer EIL1 is located between the first electron transport layer ETL1 and the charge generation layer 300. The first electron injection layer EIL1 is configured to inject electrons provided by the N-type charge generation sublayer into the first electron transport layer ETL1. The first electron transport layer ETL1 is located between the first electron injection layer EIL1 and the second light-emitting layer. The first electron injection layer EIL1 is configured to transport the electrons injected into the first electron injection layer EIL1 to the first light-emitting layer, allowing electrons to recombine with holes within the first light-emitting layer, thereby achieving light emission from the first light-emitting layer.

[0092] like Figure 9 As shown, in some examples, the third transport layer TL3 may include a second hole injection layer HIL2 and a second hole transport layer HTL2. The second hole injection layer HIL2 is located between the charge generation layer 300 and the second hole transport layer HTL2, and is configured to inject holes from the P-type charge generation sublayer into the second hole transport layer HTL2. The second hole transport layer HTL2 is located between the second hole injection layer HIL2 and the second light-emitting layer, and is configured to transport the holes injected by the second hole injection layer HIL2 to the second light-emitting layer, allowing the holes to recombine with electrons within the second light-emitting layer, thereby enabling the second light-emitting layer to emit light.

[0093] like Figure 9As shown, in some examples, the third transport layer TL3 may also include a second exciton blocking layer BL2. The second exciton blocking layer BL2 may be located between the second hole transport layer HTL2 and the second light-emitting layer, and is configured to block electrons in the second light-emitting layer from moving towards the first electrode. Therefore, the second exciton blocking layer BL2 can also be referred to as an electron blocking layer.

[0094] like Figure 9 As shown, in some examples, the fourth transport layer TL4 may include a second electron transport layer ETL2 and a second electron injection layer EIL2. The second electron injection layer EIL2 is located between the second electron transport layer ETL2 and the second electrode, and is configured to inject electrons provided by the second electrode into the second electron transport layer ETL2. The second electron injection layer EIL2 is also located between the second electron injection layer EIL2 and the second light-emitting layer, and is configured to transport the injected electrons to the second light-emitting layer, allowing electrons to recombine with holes within the second light-emitting layer, thereby enabling the second light-emitting layer to emit light.

[0095] like Figure 9 As shown, in some examples, the fourth transport layer TL4 may also include a third exciton blocking layer BL3. The third exciton blocking layer BL3 may be located between the second electron transport layer ETL2 and the second light-emitting layer, and is configured to block holes in the second light-emitting layer from moving towards the second electrode. Therefore, the third exciton blocking layer BL3 can also be referred to as a hole blocking layer.

[0096] In some examples, at least one of the first hole injection layer HIL1 and the second hole injection layer HIL2 may include materials with strong hole injection capabilities, such as copper phthalocyanine (CuPc) or HATCN, to form a monolayer film structure. In other examples, at least one of the first hole injection layer HIL1 and the second hole injection layer HIL2 may include a p-type doped hole injection material, such as NPB:F4TCNQ or TAPC:MnO3.

[0097] In some examples, the first hole injection layer HIL1 may include a first host material and a first dopant material, wherein the ratio of the first dopant material to the first host material and the total first dopant material may be 3%. For example, the first host material may be NPB (N,N'-bis(naphthyl-1-yl)-N,N'-bis(phenyl)benzidine), and the first dopant material may be a p-type dopant material, such as F4TCNQ.

[0098] In some examples, the second hole injection layer HIL2 may include a second host material and a second doped material, wherein the ratio of the second doped material to the total of the second host material and the second doped material may be 8%. The second host material may be the same as the first host material, and the second doped material may be the same as the second doped material.

[0099] In some examples, at least one of the first hole transport layer HTL1 and the second hole transport layer HTL2 may include a carbazole-based material or other materials with high hole mobility. The work function of at least one of the first hole transport layer HTL1 and the second hole transport layer HTL2 may be in the range of -5.2 eV to -5.6 eV.

[0100] In some examples, at least one of the first electron transport layer ETL1 and the second electron transport layer ETL2 may comprise a triazine material or other materials with high electron mobility. The dimension of at least one of the first electron transport layer ETL1 and the second electron transport layer ETL2 in the first direction X may be in the range of 5 nm to 50 nm.

[0101] In some examples, the second electron transport layer ETL2 may include a third host material and a third dopant material, wherein the ratio of the third dopant material to the third host material and the total third dopant material may be 50%. For example, the third host material may be TPBI (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), and the third dopant material may be LiQ, LiF, Li, Yb, etc.

[0102] In some examples, at least one of the first electron injection layer EIL1 and the second electron injection layer EIL2 may have a size in the range of 0.5 nm to 20 nm in the first direction.

[0103] In some examples, the first electron-injected layer EIL1 may include a fourth host material and a fourth dopant material, wherein the ratio of the fourth dopant material to the fourth host material and the fourth dopant material as a whole may be 2%. The fourth host material may be the same as the third host material, and the fourth dopant material may be the same as the third dopant material.

[0104] In some examples, the first electron-injected layer EIL1 may include at least one metal element. The metal element may be lithium (Li), ytterbium (Yb), cesium (Cs), calcium (Ca), or other metals. The work function of the metal element within the first electron-injected layer EIL1 may be greater than -3.5 eV.

[0105] For example, the first electron-injected layer EIL1 may consist only of lithium. Or, for another example, the first electron-injected layer EIL1 may consist of both ytterbium and cesium.

[0106] In some embodiments, the doping ratio of the metal element in the first electron-injected layer EIL1 is less than 8%. It is understood that the ratio between the total volume of the metal element in the first electron-injected layer EIL1 and the volume of the first electron-injected layer EIL1 is less than or equal to 8%. Examples include 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, or 1%.

[0107] For example, the first electron-injected layer EIL1 may consist only of lithium, with the volume ratio of lithium to the total volume of EIL1 being 7%. Alternatively, the first electron-injected layer EIL1 may include both ytterbium and cesium, with the volume ratio of ytterbium to EIL1 being 2.5%, the volume ratio of cesium to EIL1 being 4%, and the total volume ratio of the metal elements to the total volume of EIL1 being 6.5%.

[0108] In some examples, at least one of the first exciton blocking layer BL1, the second exciton blocking layer BL2, and the third exciton blocking layer BL3 may have a size in the range of 2 nm to 15 nm in the first direction.

[0109] In some examples, at least one of the second electron injection layer EIL2 and the second electron transport layer ETL2 includes at least one metal element that is the same as the metal element included in the first electron injection layer EIL1.

[0110] Understandably, at least one of the multiple metal elements included in the second electron injection layer EIL2 and the second electron transport layer ETL2 is the same as at least one of the multiple metal elements included in the first electron injection layer EIL1.

[0111] For example, the second electron injection layer EIL2 and / or the second electron transport layer ETL2 include lithium, and the first electron injection layer EIL1 includes lithium and calcium. As another example, the second electron injection layer EIL2 includes lithium, the second electron transport layer ETL2 includes calcium, and the first electron injection layer EIL1 includes lithium and calcium. Yet another example, the second electron injection layer EIL2 includes aluminum (Al), the second electron transport layer ETL2 includes calcium, and the first electron injection layer EIL1 includes calcium and cesium.

[0112] At least one of the second electron injection layer EIL2 and the second electron transport layer ETL2 includes at least one metal element that is the same as the metal element included in the first electron injection layer EIL1, which enables at least one of the second electron injection layer EIL2 and the second electron transport layer ETL2 to have the same or similar work function as the first electron injection layer EIL1, thereby improving the electron injection and transport capability inside the light-emitting device and reducing the driving voltage of the light-emitting device.

[0113] In some embodiments, the multiple film layers located on the side of the first light-emitting layer away from the first electrode in the light-emitting device collectively comprise at least three metals.

[0114] like Figure 9 As shown, the multiple film layers located on the side of the first light-emitting layer (e.g., EL1-1, EL2-1, EL3-1) away from the first electrode AE ​​in the light-emitting device may include a first electron transport layer ETL1, a first electron injection layer EIL1, an N-type charge generation sublayer 320, a P-type charge generation sublayer 310, a second hole injection layer HIL2, a second hole transport layer HTL2, a second exciton blocking layer BL2, a second light-emitting layer, a third exciton blocking layer BL3, a second electron transport layer ETL2, a second electron injection layer EIL2, and a second electrode CE.

[0115] Understandably, one or more of the aforementioned multiple film layers collectively comprise at least three metals. Exemplarily, a single film layer comprises at least three metals. For example, the second electrode CE comprises three metals. Exemplarily, multiple film layers comprise at least three metals, with different metals comprised in different film layers. For example, the second hole injection layer HIL2 comprises a first metal, the second hole transport layer HTL2 comprises a second metal, and the N-type charge generation sublayer 320 comprises a third metal. Exemplarily, multiple film layers comprise at least three metals, with different film layers comprising the same metals. For example, the second hole injection layer HIL2 comprises a first metal and a second metal, and the second hole transport layer HTL2 comprises a second metal and a third metal.

[0116] In the light-emitting device provided in this embodiment, by arranging at least three metals in multiple film layers located on the side of the first light-emitting layer away from the first electrode, the coordination relationship between the work functions of different metals inside the light-emitting device can be increased, the overall electron injection capability of the light-emitting device can be improved, thereby improving the light extraction efficiency of the light-emitting device and reducing the driving voltage required by the light-emitting device.

[0117] In some embodiments, at least three of the multiple film layers located on the side of the first light-emitting layer away from the first electrode in the light-emitting device include metal.

[0118] For example, the first electron transport layer ETL1, the second electron transport layer ETL2, and the second electrode CE all include metals, and the first electron transport layer ETL1, the second electron transport layer ETL2, and the second electrode CE together include at least three kinds of metals.

[0119] For example, the N-type charge generating sublayer 320, the second electron injection layer EIL2, and the second electrode CE all include metals, and the N-type charge generating sublayer 320, the second electron injection layer EIL2, and the second electrode CE together include at least three kinds of metals.

[0120] For example, the P-type charge generation sublayer 310, the second hole injection layer HIL2, the second hole transport layer HTL2, and the second electron injection layer EIL2 all include metals, and the P-type charge generation sublayer 310, the second hole injection layer HIL2, the second hole transport layer HTL2, and the second electron injection layer EIL2 together include at least three kinds of metals.

[0121] In this embodiment, by configuring metal in at least three film layers on the side of the first light-emitting layer away from the first electrode in the light-emitting device, the coordination relationship between the work functions of the metals in the at least three film layers can be increased, the degree of coordination of the work functions inside the light-emitting device can be expanded, the overall electron injection capability of the light-emitting device can be improved, thereby improving the light extraction efficiency of the light-emitting device and reducing the driving voltage required by the light-emitting device.

[0122] The following text will all use the format "as shown below". Figure 9 The light-emitting device shown is used as an example for illustration, but it should be considered that it is not limited to this. Figure 9 The structure shown should be considered as Figure 10 and Figure 11 The structure shown is consistent with the following description, the only difference being the presence or absence of the first electron transport layer ETL1 and the first electron injection layer EIL1, which does not affect the effects of each embodiment.

[0123] like Figure 12 As shown, in some examples, there are at least three film layers, including a first film layer 610, a second film layer 620, and a third film layer 630 arranged sequentially from the first electrode AE ​​to the second electrode CE. The first film layer 610, the second film layer 620, and the third film layer 630 are all located on the side of the first light-emitting layer EL-1 away from the first electrode AE.

[0124] The absolute value of the work function of the metal in the third film layer 630 is greater than the absolute value of the work function of the metal in the second film layer 620; the absolute value of the work function of the metal in the third film layer 630 is greater than the absolute value of the work function of the metal in the first film layer 610.

[0125] It should be noted that the absolute value of the work function of a metal in a film layer can refer to the sum of the products of the absolute values ​​of the work functions of each metal in the film layer and their respective proportions in the film layer. For example, if the second electrode includes one metal, the absolute value of the work function of that metal is the absolute value of the work function of the metal in the second electrode. As another example, if the second electrode includes silver (Ag) and magnesium (Mg), then the absolute value of the work function of silver (Ag) is the sum of the proportion of silver (Ag) in the silver and magnesium (Mg) elements, plus the absolute value of the work function of magnesium (Mg) in the magnesium and magnesium (Mg) elements. The above examples illustrate the concept of a film layer including one or two metals; it does not limit a film layer to only one or two metals. A film layer can also include three, four, or even more metals.

[0126] like Figure 12 As shown, the absolute value of the work function of the metal in the third film layer 630, which is closer to the second electrode, is greater than the absolute value of the work function of the metal in the second film layer 620, which is farther from the second electrode, and the absolute value of the work function of the metal in the first film layer 610. Since electrons move from positions with larger absolute values ​​of work function to those with smaller absolute values, this improves the ability of electrons to move from the second electrode to the first electrode, thereby improving the overall electron injection capability of the light-emitting device, increasing the light extraction efficiency of the device, and reducing the driving voltage required for the device.

[0127] In some embodiments, the above-mentioned at least three metals include a first type of metal and a second type of metal.

[0128] In some examples, metals with a work function less than -3.5 eV are called Type I metals, and metals with a work function greater than -3.5 eV are called Type II metals.

[0129] The first type of metal can include at least one of the high work function metals such as silver (Ag), aluminum (Al), gold (Au), copper (Cu), magnesium (Mg), molybdenum (Mo), and tin (Sn). The second type of metal can include at least one of the low work function metals such as lithium (Li), ytterbium (Yb), cesium (Cs), and calcium (Ca).

[0130] For example, if the second electrode comprises two types of first-type metals and one type of second-type metal, then the second electrode may include a Mg:Ag alloy and Yb. As another example, if the second electron-injected layer EIL2 comprises one type of second-type metal, then the second electron-injected layer EIL2 may include Yb.

[0131] In some examples, the work function of the first type of metal can be in the range of -5.2 eV to -3.5 eV. For example, -5.2 eV, -425 eV, -4 eV, -3.7 eV, -3.5 eV, -3.3 eV, -3 eV, -3.8 eV, or -3.5 eV.

[0132] like Figure 12 As shown, in some embodiments, the second light-emitting unit 220 includes a second light-emitting layer EL-2. In the light-emitting device, the side of the second light-emitting layer EL-2 near the first electrode AE ​​includes at least one second type of metal, and the side of the second light-emitting layer EL-2 away from the first electrode includes at least one first type of metal and at least one second type of metal.

[0133] In the light-emitting device, multiple film layers located on the side of the second light-emitting layer EL-2 near the first electrode AE ​​include a first electron transport layer ETL1, a first electron injection layer EIL1, an N-type charge generation sublayer 320, a P-type charge generation sublayer 310, a second hole injection layer HIL2, a second hole transport layer HTL2, and a second exciton blocking layer BL2. At least one of these film layers includes at least one second type of metal.

[0134] For example, a film layer located on the side of the second light-emitting layer EL-2 near the first electrode AE ​​comprises a second type of metal. For instance, the N-type charge-generating sublayer 320 comprises Yb.

[0135] For example, a film layer located on the side of the second light-emitting layer EL-2 near the first electrode AE ​​includes a variety of second-type metals. For instance, the first electron-injection layer EIL1 includes Li and Cs elements.

[0136] For example, multiple film layers located on the side of the second light-emitting layer EL-2 near the first electrode AE ​​include the same type II metal. For instance, the N-type charge-generating sublayer 320 includes Yb, and the second hole-injection layer HIL2 also includes Yb.

[0137] For example, the multiple film layers located on the side of the second light-emitting layer EL-2 near the first electrode AE ​​comprise different types of second-type metals. For instance, the first electron injection layer EIL1 comprises Li and Cs elements, and the second electron transport layer ETL1 comprises Yb elements.

[0138] In the light-emitting device, multiple film layers located on the side of the second light-emitting layer EL-2 away from the first electrode AE ​​include a third exciton blocking layer BL3, a second electron transport layer ETL2, a second electron injection layer EIL2, and a second electrode CE. At least one of these film layers includes at least one type-1 metal and at least one type-2 metal.

[0139] For example, a film layer located on the side of the second light-emitting layer EL-2 away from the first electrode AE ​​comprises at least one first type metal and at least one second type metal. For instance, the second electrode CE comprises a Mg:Ag alloy and Yb.

[0140] For example, multiple film layers located on the side of the second light-emitting layer EL-2 away from the first electrode AE ​​collectively comprise at least one first-type metal and at least one second-type metal. For instance, the second electron transport layer ETL2 comprises Li, the second electron injection layer EIL2 comprises Cs, and the second electrode CE comprises Cu. Another example is that the second electrode CE comprises a Mg:Ag alloy, and the second electron injection layer EIL2 comprises Yb. Yet another example is that the second electrode CE comprises a Mg:Ag alloy and Yb, and the second electron injection layer EIL2 comprises Yb.

[0141] In some examples, such as Figure 12 As shown, the first film layer 610 is located on the side of the second light-emitting layer closer to the first electrode; the second film layer 620 and the third film layer 630 are located on the side of the second light-emitting layer away from the first electrode.

[0142] Understandably, the first film layer 610 includes at least one type II metal. The second film layer 620 and the third film layer 630 together include at least one type I metal and at least one type II metal.

[0143] For example, the first film layer 610 is the first electron injection layer EIL2, which includes Cs elements; the second film layer 620 is the second electron transport layer ETL2, which includes Yb elements; and the third film layer 630 is the second electrode CE, which includes Ag elements.

[0144] For example, the first film layer 610 is an N-type charge generating sublayer 320, including Yb element; the second film layer 620 is a second electron injection layer EIL2, including Yb element; and the third film layer 630 is a second electrode CE, including Mg:Ag alloy and Yb element.

[0145] Since the work function of the metal in the third film layer 630 is greater than that of the metal in the first film layer 610, the third film layer 630 and the first film layer 610 work together to improve the ability of electrons to move to the side of the second light-emitting layer near the first electrode, thereby improving the performance of electron injection and transmission in the light-emitting device.

[0146] Since the work function of the metal in the third film layer 630 is greater than that of the metal in the second film layer 620, the third film layer 630 and the second film layer 620 work together to improve the ability of electrons to move to the side of the second light-emitting layer away from the first electrode, thereby improving the performance of electron injection and transmission in the light-emitting device.

[0147] In some examples, the second membrane layer 620 and the third membrane layer 630 are disposed adjacent to each other. Understandably, the second membrane layer 620 and the third membrane layer 630 are in direct contact.

[0148] For example, the second film layer 620 is the second electron injection layer EIL2, which includes Yb element; the third film layer 630 is the second electrode CE, which includes Mg:Ag alloy and Yb element.

[0149] Since the work function of the metal in the third film layer 630 is greater than that of the metal in the second film layer 620, the third film layer 630 is in direct contact with the second film layer 620, which can improve the electron injection performance of the second film layer 620, thereby improving the overall electron injection performance of the light-emitting device.

[0150] In some embodiments, the film layer having a first type of metal comprises at least two metals.

[0151] Understandably, a film layer having a first type of metal already includes at least one first type of metal, and the remaining metal may include a first type of metal, a second type of metal, or both a first type of metal and a second type of metal.

[0152] For example, if the second electrode CE includes Mg, then the second electrode CE also includes at least one metal in addition to Mg, such as Ag, Yb, or Ag and Yb.

[0153] In this embodiment, the film layer with the first type of metal includes at least two metals, which can improve the coordination between the work functions of different metals inside the film layer, thereby improving the film layer's ability to inject and transport electrons, and thus improving the overall electron injection performance of the light-emitting device.

[0154] In some examples, at least two film layers in the light-emitting device located on the side of the first light-emitting layer away from the first electrode comprise the same metal.

[0155] For example, in the light-emitting device, at least two film layers located on the side of the first light-emitting layer away from the first electrode each include a metal, and at least two film layers include the same metal. For example, the first electron transport layer ETL1 includes Li, and the second electron transport layer ETL2 includes Li.

[0156] For example, in the light-emitting device, among at least two film layers located on the side of the first light-emitting layer away from the first electrode, some film layers include one metal and others include multiple metals. For instance, the second electron injection layer EIL2 includes Yb, and the second electrode CE includes a Mg:Ag alloy and Yb.

[0157] In this embodiment, at least two film layers located on the side of the first light-emitting layer away from the first electrode in the light-emitting device include the same metal, which can simplify the matching relationship between the work functions of multiple metals and reduce the amount of material used in the fabrication of the light-emitting device.

[0158] In some embodiments, the second electrode CE, the second electron injection layer EIL2, and the charge generation layer 300 collectively comprise at least three types of metals. Specifically, the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the second electron injection layer EIL2; and the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the charge generation layer 300.

[0159] In some examples, the metals included in the second electrode CE, the second electron injection layer EIL2, and the charge generation layer 300 are different. For example, the second electrode includes silver (Ag), the second electron injection layer includes cesium (Cs), and the charge transport layer includes ytterbium (Yb).

[0160] In some examples, the second electrode CE, the second electron injection layer EIL2, and the charge generation layer 300 may include the same metal. For example, the second electrode CE may include silver (Ag), magnesium (Mg), and ytterbium (Yb), the second electron injection layer EIL2 may include ytterbium (Yb), and the charge transport layer 300 may include ytterbium (Yb).

[0161] The absolute value of the work function of silver (Ag) is greater than that of cesium (Cs), and the absolute value of the work function of silver (Ag) is greater than that of ytterbium (Yb). Similarly, the absolute value of the work function of magnesium (Mg) is greater than that of cesium (Cs), and the absolute value of the work function of magnesium (Mg) is greater than that of ytterbium (Yb).

[0162] Thus, in the two examples above, the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the second electron injection layer EIL2; and the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the charge generation layer 300.

[0163] By ensuring that the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the second electron injection layer EIL2, electrons can be better injected from the second electrode CE through the second electron injection layer EIL2 into the second light-emitting layer of the second light-emitting unit 220, thus improving the electron injection capability of the second light-emitting unit 220. Similarly, by ensuring that the absolute value of the work function of the metal in the second electrode CE is greater than the absolute value of the work function of the metal in the charge generation layer 300, electrons can be better injected from the second electrode CE through the charge generation layer 300 into the first light-emitting layer of the first light-emitting unit 210, thus improving the electron injection capability of the first light-emitting unit 210. This improves the overall electron injection capability of the light-emitting device, thereby increasing the light extraction efficiency of the light-emitting device and reducing the driving voltage required by the light-emitting device.

[0164] In some embodiments, the at least three metals include at least two first-type metals and at least one second-type metal.

[0165] By using at least two first-type metals and at least one second-type metal, the barrier height between the second electrode CE and the second electron injection layer EIL2 can be easily reduced, thereby improving the electron injection performance of the second electrode CE and the second electron injection layer EIL2, and thus improving the electron injection capability of the second light-emitting unit 220.

[0166] By using at least two first-type metals and at least one second-type metal, the barrier height between the second electrode CE and the charge generation layer 300 can be easily reduced, thereby improving the electron injection performance of the second electrode CE and the charge generation layer 300, and thus improving the electron injection capability of the first light-emitting unit 210.

[0167] For example, the absolute value of the work function of the metals in the second electrode CE can be flexibly adjusted by adjusting the ratio between at least two first-type metals in the second electrode CE; thereby matching the second electrode CE with the second electron injection layer EIL2 and / or charge generation layer 300 to improve the overall electron injection performance of the light-emitting device.

[0168] In some embodiments, the second electrode CE and the second electron injection layer EIL2 include at least two first type metals, and both the second electron injection layer EIL2 and the charge generation layer 300 include at least one second type metal.

[0169] For example, the second electrode comprises copper (Cu) and tin (Sn), the electron injection layer comprises cesium (Cs), and the charge generation layer comprises ytterbium (Yb).

[0170] For example, the second electrode comprises copper (Cu) and aluminum (Al), the electron injection layer comprises cesium (Cs) and lithium (Li), and the charge generation layer comprises ytterbium (Yb).

[0171] In some embodiments, the second electrode CE comprises two types of first-type metals. The volume ratio between the two types of first-type metals is 100:1 to 1:100. This allows for precise adjustment of the absolute value of the work function of the metals in the second electrode CE between the absolute values ​​of the work functions of the two types of first-type metals.

[0172] In some embodiments, the second electron-injected layer EIL2 may include a fifth host material and a fifth dopant material. The fifth host material is an electron-injected material, and the fifth dopant material is a material comprising a second type of metal. The fifth dopant material is doped into the fifth host material such that the second type of metal is doped into the electron-injected material.

[0173] In some embodiments, the charge generation layer 300 may include a sixth host material and a sixth doped material. The sixth host material is a charge generation material, and the sixth doped material is a material comprising a second type of metal. The sixth doped material is doped into the sixth host material such that the second type of metal is doped into the charge generation material.

[0174] In some embodiments, the charge generation layer 300 includes a first charge generation sublayer 310 and a second charge generation sublayer 320. The first charge generation sublayer 310 is the aforementioned N-type charge generation sublayer, and the second charge generation sublayer 320 is the aforementioned P-type charge generation sublayer. The N-type charge generation sublayer 310 may include a second type of metal.

[0175] In some embodiments, the N-type charge-generating sublayer 310 includes at least one second type of metal. The total volume of the second type of metal in the N-type charge-generating sublayer 310 accounts for less than or equal to 1% of the total volume of the N-type charge-generating sublayer 310. This allows for less loss of charge-generating material in the N-type charge-generating sublayer 310 and also improves the overall electron injection performance of the light-emitting device.

[0176] If the total volume of the second type of metal is in a high proportion in the N-type charge generating sublayer 310, it can easily lead to exciton quenching. By limiting the proportion of the total volume of the second type of metal in the volume of the N-type charge generating sublayer 310 to below 1%, it is possible to improve the electron transport performance of the N-type charge generating sublayer 310, prevent exciton quenching, and improve the reliability of the light-emitting device.

[0177] In some examples, the size of the N-type charge-generating sublayer 310 in the first direction X can be at... For example or

[0178] In some embodiments, the second electrode CE is a stacked structure, including a first sublayer and a second sublayer located on one side of the first sublayer. The first sublayer includes a first type of metal, and the second sublayer includes a second type of metal. For example, the first sublayer of the second electrode is a Mg:Ag alloy layer, and the second sublayer of the second electrode is a ytterbium (Yb) metal layer. Exemplarily, the thickness of the first sublayer in the first direction X can be 14 nm, and the thickness of the second sublayer in the first direction X can be between 0.5 nm and 2 nm, such as 0.5 nm, 0.7 nm, 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, or 2 nm.

[0179] In some embodiments, in the light-emitting device, the ratio between the total volume of the first type of metal and the total volume of the second type of metal is less than or equal to 20:1.

[0180] The absolute value of the work function of the first type of metal is greater than that of the second type of metal. This means that the electron transport characteristics inside the first type of metal are better than those inside the second type of metal. Therefore, in light-emitting devices, the total volume of the first type of metal is larger than that of the second type of metal, which can improve the overall electron transport performance of the light-emitting device.

[0181] In some embodiments, the ratio between the total volume of the second type of metal and the overall volume of the first type of metal and the second type of metal in the light-emitting device is greater than or equal to 5%, so as to improve the electron transport characteristics inside the light-emitting device.

[0182] In some examples, the light-emitting device includes ytterbium (Yb), silver (Ag), and magnesium (Mg), and the ratio between the sum of the volumes of silver (Ag) and magnesium (Mg) and the total volume of ytterbium (Yb), silver (Ag), and magnesium (Mg) is greater than or equal to 5%.

[0183] In some examples, the ratio of the total volume of the second type of metal to the total volume of the first and second type of metals in the light-emitting device is in the range of 6% to 9%. For example, in the example above, the ratio of the sum of the volumes of silver (Ag) and magnesium (Mg) to the total volumes of ytterbium (Yb), silver (Ag), and magnesium (Mg) is in the range of 6% to 9%.

[0184] The first type of metal has good light transmittance, and the ratio between the total of the second type of metal and the total of the first and second type of metal is in the range of 6% to 9%, which enables the light-emitting device to have high light transmittance and good electron transport performance.

[0185] In some examples, the N-type charge-generating sublayer 320 and the second electron-injecting layer EIL2 comprise Yb, and the second electrode CE comprises a Mg:Ag alloy and Yb. In the light-emitting device, the ratio of the total volume of the second type of metal to the overall volume of the first and second type of metals is in the range of 6% to 9%, which allows the overall transmittance of the second electron-injecting layer EIL2 and the second electrode CE to be greater than or equal to 50%.

[0186] In some embodiments, at least one of the at least three metals is a non-alkaline earth metal and a non-alkali metal. It can be understood that at least one of the at least three metals is both a non-alkaline earth metal and a non-alkali metal.

[0187] For example, two metals are both non-alkaline earth metals and non-alkali metals, and the other metal is an alkaline earth metal. Another example is a metal that is both non-alkaline earth metal and non-alkali metal, a metal that is an alkaline earth metal, and a metal that is an alkali metal.

[0188] Alkaline earth metals and alkali metals have higher absolute values ​​of work function. Therefore, at least one of the three metals is a non-alkaline earth metal and a non-alkali metal. This can be understood as at least one of the three metals including at least one metal with a lower absolute value of work function, such as a type II metal.

[0189] In some examples, the proportion of at least three metals that are neither alkaline earth metals nor alkali metals to at least three metals is greater than or equal to 5%, which can improve the electron transport characteristics inside the light-emitting device.

[0190] like Figure 13 As shown, in some embodiments, the absolute value of the difference between the dimension d4 of the first transmission layer TL1 in the first direction X and the dimension d5 of the fourth transmission layer TL4 in the first direction X is less than 15 nm.

[0191] Understandably, the absolute value of the difference between the spacing between the first light-emitting layer and the first electrode and the spacing between the second light-emitting layer and the second electrode is less than 15 nm.

[0192] In some examples, the first transport layer includes a first hole injection layer HIL1, a first hole transport layer HTL1, and a first exciton blocking layer BL1, and the fourth transport layer TL4 includes a second electron injection layer EIL2, a second electron transport layer ETL2, and a third exciton blocking layer BL3. The absolute value of the difference between the sum of the dimensions of the first hole injection layer HIL1, the first hole transport layer HTL1, and the first exciton blocking layer BL1 in the first direction X, and the sum of the dimensions of the second electron injection layer EIL2, the second electron transport layer ETL2, and the third exciton blocking layer BL3 in the first direction X, is less than 15 nm.

[0193] In some examples, the dimension d4 of the first transport layer TL1 in the first direction X may be greater than the dimension d5 of the fourth transport layer TL4 in the first direction X. In other examples, the dimension d4 of the first transport layer TL1 in the first direction X may be smaller than the dimension d5 of the fourth transport layer TL4 in the first direction X.

[0194] By designing the size d4 of the first transmission layer TL1 in the first direction X and the size d5 of the fourth transmission layer TL4 in the first direction X to be less than 15nm, the uniformity of the first transmission layer TL1 and the fourth transmission layer TL4 can be improved, thereby improving the matching degree between the light emitted by the first light-emitting unit 210 and the light emitted by the second light-emitting unit 220, and thus improving the overall light emission efficiency of the light-emitting device.

[0195] The smaller the absolute value of the difference between the dimension d4 of the first transmission layer TL1 in the first direction X and the dimension d5 of the fourth transmission layer TL4 in the first direction X, the higher the matching degree between the light emitted by the first light-emitting unit 210 and the light emitted by the second light-emitting unit 220. Therefore, the absolute value of the difference between the dimension d4 of the first transmission layer TL1 in the first direction X and the dimension d5 of the fourth transmission layer TL4 in the first direction X can be between 0nm and 15nm, for example, 0nm, 2nm, 4nm, 5nm, 7nm, 10nm, 12nm, 14nm or 15nm.

[0196] like Figure 13As shown, in some embodiments, the size of the second light-emitting unit 220 in the first direction X is larger than the size of the first light-emitting unit 210 in the first direction. The size of the second light-emitting unit 220 in the first direction X can refer to the distance between the first electrode and the charge-generating layer 300 in the first direction X. The size of the first light-emitting unit 210 in the first direction X can refer to the distance between the second electrode CE and the charge-generating layer 300 in the first direction X. Therefore, it can be understood that the spacing between the first electrode and the charge-generating layer 300 in the first direction X is smaller than the spacing between the second electrode CE and the charge-generating layer 300.

[0197] For example, the size of the second light-emitting unit 220 in the first direction X can refer to the sum of the sizes of the third transport layer TL3, the second light-emitting layer, and the fourth transport layer TL4 in the first direction X. For instance, the size of the second light-emitting unit 220 in the first direction X includes the sum of the sizes of the second hole injection layer HIL2, the second hole transport layer HTL2, the second exciton blocking layer BL2, the second light-emitting layer, the third exciton blocking layer BL3, the second electron transport layer ETL2, and the second electron injection layer EIL2 in the first direction X.

[0198] For example, the size of the first light-emitting unit 210 in the first direction X can refer to the sum of the size of the first transport layer TL1 in the first direction X, the size of the first light-emitting layer in the first direction X, and the size of the second transport layer TL2 in the first direction X. For instance, the size of the first light-emitting unit 210 in the first direction X includes the sum of the sizes of the first hole injection layer HIL1, the first hole transport layer HTL1, the first exciton blocking layer BL1, the first light-emitting layer, the first electron transport layer ETL1, and the first electron injection layer EIL1 in the first direction X.

[0199] For example, within the first light-emitting opening K1, the dimension d1-2 of the second light-emitting unit 220 in the first direction X is larger than the dimension d1-1 of the first light-emitting unit 210 in the first direction. As another example, within the second light-emitting opening K2, the dimension d2-2 of the second light-emitting unit 220 in the first direction X is larger than the dimension d2-1 of the first light-emitting unit 210 in the first direction. And as yet another example, within the third light-emitting opening K3, the dimension d3-2 of the second light-emitting unit 220 in the first direction X is larger than the dimension d3-1 of the first light-emitting unit 210 in the first direction.

[0200] In some examples, the ratio of the dimension of the first light-emitting unit 210 in the first direction X to the overall dimension of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is between 20% and 40%. Understandably, the ratio between the optical path length of the first light-emitting unit 210 and the overall optical path length of the first light-emitting unit 210 and the second light-emitting unit 220 is between 20% and 40%. Examples include 20%, 23%, 25%, 27%, 29%, 30%, 32%, 34%, 37%, 38%, or 40%.

[0201] In some examples, the ratio of the dimension of the second light-emitting unit 220 in the first direction X to the dimension d5 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is between 55% and 80%. Understandably, the ratio between the optical path length of the second light-emitting unit 220 and the optical path length of the entire first light-emitting unit 210 and the second light-emitting unit 220 is between 55% and 80%. For example, 55%, 58%, 59%, 60%, 61%, 63%, 66%, 68%, 70%, 71%, 75%, or 80%.

[0202] For example, within the first light-emitting opening, the ratio of the dimension d1-1 of the first light-emitting unit 210 in the first direction X to the overall dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 34%; within the first light-emitting opening, the ratio of the dimension d1-2 of the second light-emitting unit 220 in the first direction X to the overall dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 66%. As another example, within the second light-emitting opening, the ratio of the dimension d2-1 of the first light-emitting unit 210 in the first direction X to the overall dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 32%; within the second light-emitting opening, the ratio of the dimension d2-2 of the second light-emitting unit 220 in the first direction X to the overall dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 68%. For example, in the third light-emitting opening, the ratio of the dimension d3-1 of the first light-emitting unit 210 in the first direction X to the dimension d3 of the whole of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 29%; in the second light-emitting opening, the ratio of the dimension d3-2 of the second light-emitting unit 220 in the first direction X to the dimension d3 of the whole of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is 71%.

[0203] In some examples, the ratio of the size of the first light-emitting unit 210 in the first direction X to the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is at least 20%; the ratio of the size of the second light-emitting unit 220 in the first direction X to the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is at most 80%. That is, the ratio of the size of the second light-emitting unit 220 in the first direction X to the size of the first light-emitting unit 210 in the first direction X is 4.

[0204] In other examples, the ratio of the size of the first light-emitting unit 210 in the first direction X to the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is at most 40%; the ratio of the size of the second light-emitting unit 220 in the first direction X to the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X is at least 55%. That is, the ratio of the size of the second light-emitting unit 220 in the first direction X to the size of the first light-emitting unit 210 in the first direction X is 1.375.

[0205] Combining the two examples above, it can be determined that the ratio of the size of the second light-emitting unit 220 in the first direction to the size of the first light-emitting unit 210 in the first direction can be in the range of 1.375 to 4.

[0206] In some embodiments, the opening area of ​​the first light-emitting opening K1 is smaller than the opening area of ​​the second light-emitting opening K2, and the opening area of ​​the second light-emitting opening K2 is smaller than the opening area of ​​the third light-emitting opening K3. Furthermore, the wavelength of the light emitted by the first light-emitting unit 210 within the first light-emitting opening K1 is greater than the wavelength of the light emitted by the first light-emitting unit 210 within the second light-emitting opening K2, and the wavelength of the light emitted by the first light-emitting unit 210 within the second light-emitting opening K2 is greater than the wavelength of the light emitted by the first light-emitting unit 210 within the third light-emitting opening K3.

[0207] In some examples, the light-emitting device in the first light-emitting opening K1 is a red light-emitting device, the light-emitting device in the second light-emitting opening K2 is a green light-emitting device, and the light-emitting device in the third light-emitting opening K3 is a blue light-emitting device. The wavelength of the light emitted by the first light-emitting unit 210 in the first light-emitting opening K1 can be in the range of 650nm to 700nm, the wavelength of the light emitted by the first light-emitting unit 210 in the second light-emitting opening K2 can be in the range of 510nm to 540nm, and the wavelength of the light emitted by the first light-emitting unit 210 in the third light-emitting opening K3 can be in the range of 460nm to 470nm.

[0208] In some embodiments, the opening area of ​​the first light-emitting opening K1 is smaller than the opening area of ​​the second light-emitting opening K2, and the opening area of ​​the second light-emitting opening K2 is smaller than the opening area of ​​the third light-emitting opening K3. Furthermore, the wavelength of the light emitted by the second light-emitting unit 220 within the first light-emitting opening K1 is greater than the wavelength of the light emitted by the second light-emitting unit 220 within the second light-emitting opening K2, and the wavelength of the light emitted by the second light-emitting unit 220 within the second light-emitting opening K2 is greater than the wavelength of the light emitted by the second light-emitting unit 220 within the third light-emitting opening K3.

[0209] In some examples, the light-emitting device in the first light-emitting opening K1 is a red light-emitting device, the light-emitting device in the second light-emitting opening K2 is a green light-emitting device, and the light-emitting device in the third light-emitting opening K3 is a blue light-emitting device. The wavelength of the light emitted by the second light-emitting unit 220 in the first light-emitting opening K1 can be in the range of 650nm to 700nm, the wavelength of the light emitted by the second light-emitting unit 220 in the second light-emitting opening K2 can be in the range of 510nm to 540nm, and the wavelength of the light emitted by the second light-emitting unit 220 in the third light-emitting opening K3 can be in the range of 460nm to 470nm.

[0210] Since the light extraction efficiency of blue emitting materials is lower than that of red and green emitting materials, increasing the opening area of ​​the third emitting aperture K3 corresponding to the blue emitting material allows more blue light to be emitted from it, thus balancing the red and green light and improving the display effect of the display panel. Furthermore, the stability of blue emitting materials is worse than that of red emitting materials; under high current density, the light-emitting device of blue emitting material decays more quickly. Increasing the opening area of ​​the third emitting aperture allows for a lower current density under the same voltage, slowing down the decay of the light-emitting device and thus improving its efficiency and lifespan.

[0211] like Figure 13 As shown, in some embodiments, the size d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X; the size d1-2 of the first light-emitting unit 210 in the first direction X in the second light-emitting opening K2; and the size d1-3 of the first light-emitting unit 210 in the first direction X in the third light-emitting opening K3; at least two of the three are not equal.

[0212] It should be noted that the size of the first light-emitting unit 210 in the first direction X in different light-emitting openings can be understood as the optical path length of the light rays in the light-emitting opening between the first electrode and the second light-emitting unit 220.

[0213] By using optical path lengths of different dimensions in the first direction X, it is possible to make light of different wavelengths reach their respective optimal light extraction efficiency, thereby improving the light extraction efficiency of the display panel.

[0214] In some examples, the size d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X is greater than or less than the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X; the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X is equal to the size d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 in the first direction X.

[0215] In some examples, the size d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X is equal to the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X; the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X is greater than or less than the size d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 in the first direction X.

[0216] In some examples, the size d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X is larger than the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X; the size d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X is larger than the size d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 in the first direction X.

[0217] In some examples, the display panel 100 is a top-emitting display panel, and the first electrode is ITO / Ag / ITO. The optical path length of the light within the light-emitting opening between the first electrode and the second light-emitting unit 220 may also include the size of the ITO in the first direction X. Since each light-emitting opening is provided with a first electrode, the relationship between the optical path lengths of the light within different light-emitting openings and the first electrode and the second light-emitting unit 220 is not changed.

[0218] Through inventive work, the inventors of this disclosure discovered that the longer the wavelength, the greater the optical path required to achieve optimal light extraction efficiency. Therefore, in this example, the light within the first light-emitting opening K1, the second light-emitting opening K2, and the third light-emitting opening K3 can all achieve optimal light extraction efficiency, thereby improving the light extraction efficiency of the display panel.

[0219] In some embodiments, the dimensions of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X are d1-2; the dimensions of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X are d2-2; the dimensions of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X are d3-2; at least two of the three are not equal.

[0220] It should be noted that the size of the second light-emitting unit 220 in the first direction X in different light-emitting openings can be understood as the optical path length of the light rays in the light-emitting opening between the first light-emitting unit 210 and the second electrode.

[0221] By using optical path lengths of different dimensions in the first direction X, it is possible to make light of different wavelengths reach their respective optimal light extraction efficiency, thereby improving the light extraction efficiency of the display panel.

[0222] In some examples, the size d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than or less than the size d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the size d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is equal to the size d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0223] In some examples, the size d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is equal to the size d2-2 of the second light-emitting unit 220 in the first direction X in the second light-emitting opening K2; the size d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than or less than the size d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0224] In some examples, the size d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is larger than the size d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the size d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is larger than the size d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0225] Since the longer the wavelength, the longer the optical path required to achieve the best light emission efficiency, this example can facilitate the light in the first light emission opening K1, the second light emission opening K2, and the third light emission opening K3 to achieve the best light emission efficiency, thereby improving the light emission efficiency of the display panel.

[0226] In some embodiments, at least two of the following dimensions are not equal: the overall size d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X; the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; and the overall size d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0227] It should be noted that the dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in different light-emitting openings along the first direction X can be understood as the dimensions of the microcavity structure corresponding to the light rays within the light-emitting opening along the first direction X.

[0228] By using microcavity structures of different sizes in the first direction X to act on light of different wavelengths, it is possible to make light of different wavelengths achieve their respective optimal light extraction efficiency, thereby improving the light extraction efficiency of the display panel.

[0229] In some examples, the overall size d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than or less than the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X in the second light-emitting opening K2; the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is equal to the overall size d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0230] In some examples, the overall size d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is equal to the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than or less than the overall size d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0231] In some examples, the overall size d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the overall size d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K2 in the first direction X is greater than the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K3 in the first direction X.

[0232] In some examples, the overall size d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the overall size d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than the overall size d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0233] Since a longer wavelength requires a longer optical path to achieve optimal light extraction efficiency, and the size of the microcavity structure in the first direction X is positively correlated with the optical path, this example facilitates optimal light extraction efficiency for the light within the first light-emitting opening K1, the second light-emitting opening K2, and the third light-emitting opening K3, thereby improving the light extraction efficiency of the display panel.

[0234] In some embodiments, at least two of the following ratios are not equal: the ratio between the size of the first light-emitting unit 210 and the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1, the ratio between the size of the first light-emitting unit 210 and the overall size of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K2, and the ratio between the size of the first light-emitting unit 210 and the overall size of the first light-emitting unit 220 in the first light-emitting opening K3.

[0235] That is, the ratio between the dimension d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X and the dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 as a whole in the first direction X; the ratio between the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 and the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 as a whole in the first direction X; and the ratio between the dimension d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 and the dimension d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 as a whole in the first direction X; at least two of the three are not equal.

[0236] It should be noted that the larger the ratio between the dimensions of the first light-emitting unit 210 and the overall dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X, the greater the optical path of the light in the light-emitting opening between the first electrode and the second light-emitting unit 220.

[0237] By designing different ratios between the dimensions of the first light-emitting unit 210 and the overall dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X within different light-emitting openings, it is possible to facilitate the achievement of optimal light extraction efficiency for light of different wavelengths, thereby improving the light extraction efficiency of the display panel.

[0238] In some examples, the ratio between the dimension d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X and the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than or less than the ratio between the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 and the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the ratio between the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 and the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is equal to the ratio d3 of the dimension d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 and the dimension d3 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0239] In some examples, the ratio between the dimension d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X and the dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 as a whole in the first direction X is equal to the ratio between the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 and the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 as a whole in the first direction X; the ratio between the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 and the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than or less than the ratio between the dimension d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 and the dimension d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0240] In some examples, the ratio of the dimension d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 as a whole in the first direction X is greater than the ratio of the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 to the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 as a whole in the first direction X; the ratio of the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 to the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than the ratio of the dimension d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 to the dimension d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 as a whole in the first direction X.

[0241] For example, the ratio of the dimension d1-1 of the first light-emitting unit 210 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is 34%; the ratio of the dimension d2-1 of the first light-emitting unit 210 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is 32%; and the ratio of the dimension d3-1 of the first light-emitting unit 210 in the third light-emitting opening K3 in the first direction X to the dimension d3 of the first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X is 29%.

[0242] Since a longer wavelength requires a longer optical path to achieve optimal light extraction efficiency, this example ensures that the light from the first light-emitting opening K1, the second light-emitting opening K2, and the third light-emitting opening K3 all achieve optimal light extraction efficiency, thereby improving the light extraction efficiency of the display panel.

[0243] In some embodiments, the ratio between the dimensions of the second light-emitting unit 220 and the overall dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X; the ratio between the dimensions of the second light-emitting unit 220 and the overall dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X in the second light-emitting opening K2; and the ratio between the dimensions of the second light-emitting unit 220 and the overall dimensions of the first light-emitting unit 210 and the second light-emitting unit 220 in the first direction X in the third light-emitting opening K3; at least two of the three are not equal.

[0244] That is, the ratio between the dimension d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X and the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X; the ratio between the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X and the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; and the ratio between the dimension d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the third light-emitting opening K3 in the first direction X; at least two of the three are not equal.

[0245] In some examples, the ratio of the dimension d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is greater than or less than the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the second light-emitting opening K2 to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is equal to the ratio of the dimension d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the third light-emitting opening K3 to the dimension d3 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0246] In some examples, the ratio of the dimension d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is equal to the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is greater than or less than the ratio of the dimension d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X to the dimension d3 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0247] In some examples, the ratio of the dimension d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is less than the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X; the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the second light-emitting opening K2 to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is less than the ratio of the dimension d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 to the dimension d3 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X.

[0248] For example, the ratio of the dimension d1-2 of the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X to the dimension d1 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the first light-emitting opening K1 in the first direction X is 66%; the ratio of the dimension d2-2 of the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X to the dimension d2 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the second light-emitting opening K2 in the first direction X is 68%; and the ratio of the dimension d3-2 of the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X to the dimension d3 of the entire first light-emitting unit 210 and the second light-emitting unit 220 in the third light-emitting opening K3 in the first direction X is 71%.

[0249] In this example, the light emitted from the first light-emitting opening K1, the second light-emitting opening K2, and the third light-emitting opening K3 can all achieve optimal light emission efficiency, thereby improving the light emission efficiency of the display panel.

[0250] like Figure 2 As shown, in some embodiments, the plurality of light-emitting openings include at least one light-emitting opening unit KU. A light-emitting opening unit KU includes a first light-emitting opening K1, a second light-emitting opening K2, and a third light-emitting opening K3 corresponding to different colors.

[0251] One light-emitting aperture unit KU corresponds to one pixel unit area PU. The number of light-emitting apertures in a light-emitting aperture unit KU is equal to the number of sub-pixel areas in the pixel unit area. Multiple light-emitting apertures in a light-emitting aperture unit KU correspond one-to-one to multiple sub-pixel areas in a pixel unit area PU.

[0252] In some embodiments, within a light-emitting opening unit KU, the total volume V1 of the light-emitting devices in the first light-emitting opening K1; the total volume V2 of the light-emitting devices in the second light-emitting opening K2; and the total volume V3 of the light-emitting devices in the third light-emitting opening K3; at least two of the three are not equal.

[0253] Because the materials used in the light-emitting devices within different light-emitting openings vary, and these materials exhibit different levels of stability—for example, their tolerance to current and voltage, and their attenuation trends differ—designing light-emitting devices with different volumes for different light-emitting openings can specifically improve the stability of the light-emitting devices, facilitating the achievement of optimal stability for different light-emitting devices.

[0254] A light-emitting opening unit KU may include one or more first light-emitting openings K1, one or more second light-emitting openings K2, and one or more third light-emitting openings K3.

[0255] When a light-emitting opening unit KU includes a first light-emitting opening K1, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 refers to the volume of the light-emitting devices in that first light-emitting opening K1; when a light-emitting opening unit KU includes multiple first light-emitting openings K1, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 refers to the sum of the volumes of the light-emitting devices in each of the first light-emitting openings K1.

[0256] Similarly, the meaning of the total volume V2 of the light-emitting devices in the second light-emitting opening K2 and the meaning of the total volume V3 of the light-emitting devices in the third light-emitting opening K3 are basically the same as the meaning of the total volume V1 of the light-emitting devices in the first light-emitting opening K1, and will not be repeated here.

[0257] In some examples, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is greater than or less than the total volume V2 of the light-emitting devices in the second light-emitting opening K2; the total volume V2 of the light-emitting devices in the second light-emitting opening K2 is equal to the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0258] In some examples, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is equal to the total volume V2 of the light-emitting devices in the second light-emitting opening K2; the total volume V2 of the light-emitting devices in the second light-emitting opening K2 is greater than or less than the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0259] In some examples, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is less than the total volume V2 of the light-emitting devices in the second light-emitting opening K2; the total volume V2 of the light-emitting devices in the second light-emitting opening K2 is less than the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0260] Taking the light-emitting device within the third light-emitting opening as an example, the stability of the light-emitting device within the third light-emitting opening is relatively weak, and it decays rapidly under high current density. In this example, the volume of the light-emitting device within the third light-emitting opening is increased, so that it can reduce the current density under the same voltage, delay the decay of the light-emitting device, and thus improve the efficiency and lifespan of the light-emitting device.

[0261] In some embodiments, the total volume V2 of the light-emitting devices within the second light-emitting opening K2 is greater than half the total volume V1 of the light-emitting devices within the first light-emitting opening K1. That is, the ratio between the total volume V2 of the light-emitting devices within the second light-emitting opening K2 and the total volume V1 of the light-emitting devices within the first light-emitting opening K1 is greater than 50%. For example, 51%, 55%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, etc.

[0262] In some embodiments, the total volume V3 of the light-emitting devices within the third light-emitting opening K3 is greater than half the total volume V1 of the light-emitting devices within the first light-emitting opening K1. That is, the ratio between the total volume V3 of the light-emitting devices within the third light-emitting opening K3 and the total volume V1 of the light-emitting devices within the first light-emitting opening K1 is greater than 50%. For example, 51%, 55%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, etc.

[0263] In some embodiments, the number of first light-emitting openings K1, the number of second light-emitting openings K2, and the number of third light-emitting openings K3 within a light-emitting opening unit KU are all equal. For example, a light-emitting opening unit KU includes one first light-emitting opening K1, one second light-emitting opening K2, and one third light-emitting opening K3.

[0264] In this case, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 can be greater than or equal to the total volume V2 of the light-emitting devices in the second light-emitting opening K2; the total volume V1 of the light-emitting devices in the first light-emitting opening K1 can be greater than or equal to the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0265] In other words, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is neither less than the total volume V2 of the light-emitting devices in the second light-emitting opening K2, nor less than the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0266] In some examples, the ratio of the total volume V2 of the light-emitting devices in the second light-emitting opening K2 to the total volume V1 of the light-emitting devices in the first light-emitting opening K2 is in the range of 0.6 to 1. For example, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 1.

[0267] In some examples, the ratio of the total volume V3 of the light-emitting devices in the third light-emitting opening K3 to the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is in the range of 0.5 to 0.9. For example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9.

[0268] In some embodiments, at least two of the number of first light-emitting openings K1, the number of second light-emitting openings K2, and the number of third light-emitting openings K3 within a light-emitting opening unit KU are not equal. For example, a light-emitting opening unit KU includes one first light-emitting opening K1, two second light-emitting openings K2, and one third light-emitting opening K3.

[0269] In some examples, the ratio of the total volume V2 of the light-emitting devices in the second light-emitting opening K2 to the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is in the range of 0.8 to 1.6. For example, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, or 1.6.

[0270] The stability of the light-emitting device in the second light-emitting aperture is worse than that in the first light-emitting aperture. Under high current density, the light-emitting device in the second light-emitting aperture decays faster. Therefore, it is necessary to increase the volume of the light-emitting device in the third light-emitting aperture so that it can reduce the current density under the same voltage, delay the decay of the light-emitting device, and thus improve the efficiency and lifespan of the light-emitting device.

[0271] In some examples, the ratio of the total volume V3 of the light-emitting devices in the third light-emitting opening K3 to the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is in the range of 1 to 2.3. For example, 1, 1.1, 1.2, 1.22, 1.3, 1.5, 1.8, 2, 2.1 or 2.3.

[0272] The stability of the light-emitting device in the third light-emitting aperture is worse than that in the first light-emitting aperture. Under high current density, the light-emitting device in the third light-emitting aperture decays faster. Therefore, it is necessary to increase the volume of the light-emitting device in the third light-emitting aperture so that it can reduce the current density under the same voltage, delay the decay of the light-emitting device, and thus improve the efficiency and lifespan of the light-emitting device.

[0273] In other words, the total volume V1 of the light-emitting devices in the first light-emitting opening K1 is not greater than the total volume V3 of the light-emitting devices in the third light-emitting opening K3.

[0274] like Figure 2 As shown, the light extraction layer CPL covers the light-emitting device layer LDL, for example, the light extraction layer CPL is directly located on the second electrode CE. The light extraction layer CPL can improve the light extraction efficiency of the light-emitting device layer LDL. The light extraction layer CPL has a large refractive index and a small absorption coefficient.

[0275] In some examples, the size of the light extraction layer CPL in the first direction X can be in the range of 50 nm to 80 nm. The refractive index of the light extraction layer CPL for light with a wavelength of 460 nm can be greater than or equal to 1.8. For example, 1.8, 1.9, 2.0, 2.1, etc., are not limited here.

[0276] like Figure 8As shown, the encapsulation layer TFE is used to encapsulate the light-emitting functional layer LDL and the light extraction layer CPL. In some embodiments, the encapsulation layer TFE may include a first encapsulation layer ENL1, a second encapsulation layer ENL2, and a third encapsulation layer ENL3 stacked together. For example, the first encapsulation layer ENL1 and the third encapsulation layer ENL3 are made of inorganic materials, which are selected from at least one of silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, silicon oxynitride (SiON), or lithium fluoride. As another example, the second encapsulation layer ENL2 is made of organic materials, which are at least one of acrylic resin, methacrylic resin, polyisoprene, vinyl resin, epoxy resin, polyurethane resin, cellulose resin, or dinaphthalene-containing resin. Those skilled in the art can change the number of layers, materials, and structure of the thin-film encapsulation layer TFE as needed, and this disclosure is not limited thereto.

[0277] To demonstrate the influence of metals with different absolute work function values ​​on the electron injection characteristics of light-emitting devices, this disclosure provides the following five experimental schemes for comparison. The quality of electron injection characteristics in the light-emitting device is demonstrated by detecting the current density of the second electrode. The higher the current density of the second electrode in the light-emitting device, the better the electron injection performance of the device.

[0278] Option 1: The second electrode CE comprises two types of first-type metals and one type of second-type metal, and the second electron injection layer EIL2 comprises one type of second-type metal.

[0279] Option 2: The second electrode CE comprises two types of first-type metals, and the second electron injection layer EIL2 comprises one type of second-type metal.

[0280] Option 3: The second electrode CE comprises two types of first-type metals and one type of second-type metal, and the second electron injection layer EIL2 does not contain any metal.

[0281] Option 4: The second electrode CE includes two types of first-class metals, and the second electron injection layer EIL2 does not include metals.

[0282] Option 5: The second electrode CE comprises a type 1 metal.

[0283] Figure 14 The figure shows the current density variation curves of the second electrode CE of the light-emitting device under different driving voltages for five different schemes. It can be found that, in the order of schemes 1 to 5, the current density of the second electrode decreases progressively under the same driving voltage. Among them, schemes 1 to 4 significantly improve the current density of the second electrode CE under low-voltage driving compared to the traditional scheme 5.

[0284] As shown in Table 1, a comparison between Scheme 1 and Scheme 2 reveals that adding a second type of metal to the second electrode CE can further improve the light extraction efficiency of the light-emitting device and further reduce the driving voltage of the light-emitting device.

[0285]

[0286] Table 1

[0287] In summary, the light-emitting devices and display panels provided in some embodiments of this disclosure, by incorporating at least three metals into the second electrode, the second electron injection layer, and the charge generation layer, such that the absolute value of the work function of the metal in the second electrode is greater than the absolute value of the work function of the metal in the second electron injection layer, enable electrons to be injected more effectively from the second electrode through the second electron injection layer into the second light-emitting layer of the second light-emitting unit, thereby improving the electron injection capability in the second light-emitting unit. Furthermore, by ensuring that the absolute value of the work function of the metal in the second electrode is greater than the absolute value of the work function of the metal in the charge generation layer, electrons can be injected more effectively from the second electrode through the charge generation layer into the first light-emitting layer of the first light-emitting device, thereby improving the electron injection capability in the first light-emitting unit. This enhances the overall electron injection capability of the light-emitting device, thereby improving its light extraction efficiency and reducing the required driving voltage.

[0288] 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 light emitting device, characterized by, include: A first electrode, at least two light-emitting units, and a second electrode are stacked sequentially along a first direction; The at least two light-emitting units include a first light-emitting unit, a second light-emitting unit located between the first light-emitting unit and the second electrode, and a charge-generating layer located between the first light-emitting unit and the second light-emitting unit; The first light-emitting unit includes a first light-emitting layer. In the light-emitting device, among the multiple film layers located on the side of the first light-emitting layer away from the first electrode, two adjacent film layers include at least three metals, and the absolute value of the work function of at least two metals is greater than 3.5 eV, and the absolute value of the work function of at least one metal is less than 3.5 eV. The two adjacent film layers include the same metal.

2. The light emitting device of claim 1, wherein, One of the two adjacent membrane layers comprises at least three metals.

3. The light-emitting device according to claim 1, characterized in that, One of the two adjacent membrane layers comprises at least two metals, wherein the absolute value of the work function of at least one metal is greater than 3.5 eV and the absolute value of the work function of at least one metal is less than 3.5 eV.

4. The light-emitting device according to claim 1, characterized in that, The absolute value of the work function of the same metal is less than 3.5 eV.

5. The light-emitting device according to claim 1, characterized in that, The two adjacent films comprise different metals, and both adjacent films comprise metals with an absolute work function of less than 3.5 eV.

6. The light-emitting device according to any one of claims 1 to 5, characterized in that, The second light-emitting unit includes a second light-emitting layer and a second electron injection layer located between the second light-emitting layer and the second electrode; The two adjacent membrane layers include the second electron injection layer and the second electrode.

7. The light-emitting device according to claim 1, characterized in that, The charge generation layer includes a first charge generation sublayer and a second charge generation sublayer; the first charge generation sublayer is located between the first light-emitting unit and the second charge generation sublayer. The first charge-generating sublayer comprises at least one metal, and the absolute value of the work function of the metal in the first charge-generating sublayer is less than 3.5 eV.

8. The light-emitting device according to claim 1, characterized in that, The second light-emitting unit includes a second light-emitting layer and a second electron transport layer located between the second light-emitting layer and the second electrode; The second electron transport layer and the charge generation layer are made of the same metal.

9. The light-emitting device according to claim 1, characterized in that, The film layer furthest from the first electrode among the two adjacent film layers includes at least one of silver, aluminum, gold, copper, magnesium, molybdenum, and tin. The film layer closest to the first electrode among the two adjacent film layers includes at least one of lithium, ytterbium, cesium, and calcium.

10. A light-emitting device, characterized in that, include: A first electrode, at least two light-emitting units, and a second electrode are stacked sequentially along a first direction; The at least two light-emitting units include a first light-emitting unit, a second light-emitting unit located between the first light-emitting unit and the second electrode, and a charge-generating layer located between the first light-emitting unit and the second light-emitting unit; The first light-emitting unit includes a first light-emitting layer. In the light-emitting device, each of the first film layer, the second film layer, and the third film layer located on the side of the first light-emitting layer away from the first electrode includes at least one metal, and together they include at least three metals. The distances from the first film layer, the second film layer, and the third film layer to the first electrode increase sequentially. The second film layer and the third film layer are disposed adjacent to each other; The absolute value of the work function of at least one metal in the third film layer is greater than the absolute value of the work function of at least one metal in the second film layer; the absolute value of the work function of at least one metal in the third film layer is greater than the absolute value of the work function of at least one metal in the first film layer; the first film layer, the second film layer, and the third film layer comprise the same metal.

11. The light-emitting device according to claim 10, characterized in that, The third film layer comprises at least two metals; the absolute value of the work function of each metal in the third film layer is not less than the absolute value of the metal in the second film layer.

12. The light-emitting device according to claim 10, characterized in that, The absolute value of the work function of the same metal is less than 3.5 eV.

13. The light-emitting device according to claim 10, characterized in that, The second light-emitting unit includes a second light-emitting layer; the first film layer is located on the side of the second light-emitting layer closer to the first electrode; the second film layer and the third film layer are located on the side of the second light-emitting layer away from the first electrode.

14. The light-emitting device according to claim 12, characterized in that, The absolute value of the work function of the metal in the first film layer is less than 3.5 eV, and the proportion of the volume of the metal in the first film layer to the volume of the first film layer is less than or equal to 1%.

15. A display panel, characterized in that, include: The pixel defining layer has multiple light-emitting openings; The light-emitting device is located inside the light-emitting opening; The light-emitting device is the light-emitting device as described in any one of claims 1 to 14.

Images