Light-emitting diode and indicator device

Abstract

A light-emitting diode is provided. The light-emitting diode comprises a light-emitting layer. The light-emitting layer comprises one or more first layers and one or more second layers in a stacked structure. Each first layer of the one or more first layers comprises an organic functional material of a first type doped with an organic functional material of a second type. Each second layer of the one or more second layers comprises an organic functional material of the first type without doping with an organic functional material of the second type. The light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer.

Description

TECHNICAL AREA

[0001] The present invention relates to display technology, in particular to a light-emitting diode and a display device. BACKGROUND

[0002] Organic light-emitting diode (OLED) displays are currently a hotspot in flat panel display research. Unlike thin-film transistor liquid crystal displays (TFT-LCDs), which use a stable voltage to control brightness, OLED displays are driven by a drive current that must be kept constant to control the illumination. An OLED display panel comprises numerous pixel units configured with pixel driver circuits arranged in multiple rows and columns. Each pixel driver circuit includes a driver transistor with a gate terminal connected to one gate line per row and a drain terminal connected to one data line per column.When the line controlling the pixel unit is switched on, the switching transistor connected to the driver transistor is turned on, and the data voltage is applied from the data line via the switching transistor to the driver transistor, causing the driver transistor to output a current corresponding to the data voltage to an OLED device. The OLED device is then driven to emit light at the appropriate brightness. SUMMARY

[0003] In one aspect, the present disclosure provides a light-emitting diode comprising a light-emitting layer; wherein the light-emitting layer comprises one or more first layers and one or more second layers in a stacked structure; each first layer of the one or more first layers comprises an organic functional material of a first type doped with an organic functional material of a second type; each second layer of the one or more second layers comprises an organic functional material of the first type without doping with an organic functional material of the second type; wherein the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer.

[0004] Optionally, the light-emitting layer comprises a start layer and a last layer, which are two outermost layers on opposite sides of the light-emitting layer; and the start layer and the last layer of the light-emitting layer are two second layers of one or more second layers.

[0005] Optionally, two adjacent first layers of one or more first layers are separated from each other by a second layer of one or more second layers; and two adjacent second layers of one or more second layers are separated from each other by a first layer of one or more first layers.

[0006] Optionally, the weight percentage of the second type of organic functional material in one or more first layers ranges from approximately 20% to approximately 50%.

[0007] Optionally, the light-emitting diode further comprises a hole transport layer and an electron transport layer; wherein any single first layer of the one or more first layers is spaced apart from the hole transport layer by at least one second layer of the one or more second layers; and any single first layer of the one or more first layers is spaced apart from the electron transport layer by at least one second layer of the one or more second layers.

[0008] Optionally, the light-emitting layer further comprises one or more third layers; wherein the one or more first layers, the one or more second layers and the one or more third layers are present in the stacked structure; and each third layer of the one or more third layers comprises an organic functional material of the second type and the organic functional material of the first type is not present.

[0009] Optionally, the respective first layer is in direct contact on one side with the respective second layer and on the other side with a respective third layer; and the light-emitting layer comprises one or more three-layer structures in the stacked structure, wherein each three-layer structure of the one or more three-layer structures comprises a single second layer, a single first layer stacked on top of the single second layer, and a single third layer stacked on a side of the single first layer away from the single second layer.

[0010] Optionally, two adjacent first layers of one or more first layers are separated from each other by a second layer of one or more second layers or a third layer of one or more third layers; and any single first layer of one or more first layers separates a second layer of one or more second layers and a third layer of one or more third layers.

[0011] Optionally, the one or more second layers comprise at least one first corresponding second layer and one second corresponding second layer; the first corresponding second layer comprises a first organic functional material of the first type without doping an organic functional material of the second type; the second corresponding second layer comprises a second organic functional material of the first type without doping an organic functional material of the second type; the first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type; and the first organic functional material of the first type is different from the second organic functional material of the first type.

[0012] Optionally, the first organic functional material of the first type is a p-type organic functional material of the first type; and the second organic functional material of the first type is an n-type organic functional material of the first type.

[0013] Optionally, the second corresponding second layer is located on a side of the first corresponding second layer away from the hole transport layer; and the first corresponding second layer is located on a side of the second corresponding second layer away from the electron transport layer.

[0014] Optionally, the one or more first layers comprise at least one first corresponding first layer and a second corresponding first layer; the first corresponding first layer comprises a first organic functional material of the first type doped with an organic functional material of the second type; the second corresponding first layer comprises a second organic functional material of the first type doped with an organic functional material of the second type; the first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type; and the first organic functional material of the first type is different from the second organic functional material of the first type.

[0015] Optionally, the first organic functional material of the first type is a p-type organic functional material of the first type; and the second organic functional material of the first type is an n-type organic functional material of the first type.

[0016] Optionally, the second corresponding first layer is located on a side of the first corresponding first layer furthest from the hole transport layer; and the first corresponding first layer is located on a side of the second corresponding first layer furthest from the electron transport layer.

[0017] Optionally, the one or more first layers include a first corresponding first layer, a second corresponding first layer, and a third corresponding first layer; the first corresponding first layer is a first layer of a first color; the second corresponding first layer is a first layer of a second color; and the third corresponding first layer is a first layer of a third color; and the first color, the second color, and the third color are three different colors.

[0018] Optionally, the one or more first layers may further comprise one or more fourth corresponding first layers that lie at least partially outside an exciton recombination region of the light-emitting layer.

[0019] Optionally, the light-emitting layer comprises a first bilayer structure comprising a first individual second layer and the first corresponding first layer on the first individual second layer; a second bilayer structure comprising a second individual second layer and the second corresponding first layer on the second individual second layer; and a third bilayer structure comprising a third individual second layer and the third corresponding first layer on the third individual second layer; wherein the third bilayer structure is located on a side of the second bilayer structure opposite the first bilayer structure; the first individual second layer, the second individual second layer, and the third individual second layer are distinct layers;and the first corresponding first layer, the second corresponding first layer, and the third corresponding first layer are different layers.

[0020] Optionally, the light-emitting layer comprises a first bilayer structure comprising a first individual second layer and the fourth corresponding first layer on the first individual second layer; a second bilayer structure comprising a second individual second layer and the first corresponding first layer on the second individual second layer; a third bilayer structure comprising a third individual second layer and the second corresponding first layer on the third individual second layer; and a fourth bilayer structure comprising a fourth individual second layer and the third corresponding first layer on the fourth individual second layer and a final layer that is one or more of the second layers;wherein the third bilayer structure is located on a side of the second bilayer structure furthest from the first bilayer structure, and the fourth bilayer structure is located on a side of the third bilayer structure furthest from the second bilayer structure.

[0021] Optionally, the light-emitting diode comprises a first light-emitting layer; a charge-generating layer on the first light-emitting layer; and a second light-emitting layer on a side of the charge-generating layer furthest from the first light-emitting layer; wherein the charge-generating layer comprises an n-doped layer and a p-doped layer on a side of the n-doped layer furthest from the first light-emitting layer.

[0022] In another aspect, the present disclosure provides a display device comprising the light-emitting diode described herein or produced by a method described herein and a pixel driver circuit configured to drive the light emission of the light-emitting diode. BRIEF DESCRIPTION OF THE FIGURES

[0023] The following figures are merely examples to illustrate various disclosed embodiments and are not intended to limit the scope of the present invention. Fig. Figure 1 is a schematic representation showing the structure of a corresponding light-emitting diode. Fig. Figure 2 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 3 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Fig. Figure 4 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 5 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Fig. Figure 6 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 7 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Fig. Figure 8 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 9 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Fig. 10A to Fig. Figure 10E illustrates a method for determining an exciton recombination area in a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 11 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Fig. Figure 12 is a schematic representation showing the structure of a display substrate in some embodiments according to the present disclosure. Fig. Figure 13 is a circuit diagram illustrating the structure of a pixel driver circuit in some embodiments according to the present disclosure. DETAILED DESCRIPTION

[0024] The disclosure will now be described in more detail with reference to the following embodiments. It should be noted that the following descriptions of some embodiments are presented here only for illustrative and descriptive purposes. They are not intended to be exhaustive or limited to the exact disclosed form.

[0025] Fig. Figure 1 is a schematic representation showing the structure of a relevant light-emitting diode. Referring to Fig. 1. The light-emitting diode in question comprises a base substrate BS, an anode AD on the base substrate BS, a light-emitting layer EL on a side of the anode AD furthest from the base substrate BS, and a cathode CD on a side of the light-emitting layer EL furthest from the base substrate BS. Optionally, the light-emitting diode in question further comprises a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, and an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS.

[0026] In the light-emitting diode in question, the light-emitting layer EL comprises, in some embodiments, a quantum well structure, e.g., a multiple quantum well structure. In particular, the light-emitting layer EL in the light-emitting diode comprises a number of n host material layers (e.g., HML1, ..., HMLn) and a number of (n-1) guest material layers, where n is an integer greater than 1. In one example, a number of (n-1) host material layers (e.g., HML1 to HML(n-1)) and a number of (n-1) guest material layers are stacked alternately. In another example, a starting layer and a final layer of the light-emitting layer EL are host material layers (e.g., HML1 and HMLn). The quantum wells limit charge carrier recombination within the light-emitting layer EL, increase the concentrations of electron and hole carriers, and enhance the recombination efficiency of the charge carriers.However, if the charge carrier concentrations are higher than the corresponding values, concentration quenching occurs, and the emission intensity of the light-emitting layer (EL) actually decreases. Since concentration quenching shortens the device's lifetime, the thickness of the guest material layers must be precisely controlled, e.g., to less than 5 nm. This problem makes the fabrication of the corresponding light-emitting diode very complicated and leads to irregularities in mass production.

[0027] Accordingly, the present disclosure provides, among other things, a light-emitting diode and a display device that substantially eliminate one or more of the problems arising from limitations and disadvantages of the prior art. In one aspect, the present disclosure provides a light-emitting diode. In some embodiments, the light-emitting diode comprises a light-emitting layer. Optionally, the light-emitting layer comprises one or more first layers and one or more second layers in a stacked structure. Optionally, each first layer of the one or more first layers comprises an organic functional material of a first type doped with an organic functional material of a second type.Optionally, each second layer of one or more second layers comprises an organic functional material of the first type without doping an organic functional material of the second type. Optionally, the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer.

[0028] Fig. Figure 2 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Referring to Fig. 2. In some embodiments, the light-emitting layer comprises one or more first layers and one or more second layers stacked on top of each other. In some embodiments, each first layer of the one or more first layers comprises an organic functional material of a first type (e.g., a host material) doped with an organic functional material of a second type (e.g., a guest material), and each second layer of the one or more second layers comprises an organic functional material of the first type without doping with an organic functional material of the second type; that is, the organic functional material of the second type is not present in the respective second layer. In one example, each first layer comprises a host material doped with a guest material, and each second layer comprises a host material that is not doped with a guest material. Fig. 2. The first one or more layers are designated as L1 and the second one or more layers as L2. The dashed line in Fig. 2 means that the alternating stacked first layer and the second layer can be repeated one or more times.

[0029] In one example, the organic functional materials of the first type are identical in one or more first layers L1. In another example, the organic functional materials of the first type are different in at least two of the one or more first layers L1.

[0030] In one example, the second type of organic functional materials are identical in one or more first layers L1. In another example, the second type of organic functional materials are different in at least two of the one or more first layers L1.

[0031] In one example, the organic functional materials of the first type are identical in one or more second layers L2. In another example, the organic functional materials of the first type differ in at least two of the one or more second layers L2.

[0032] In one example, the organic functional materials of the first type are the same in the respective first layer and in the respective second layer. In another example, the organic functional materials of the first type are different in the respective first layer and in the respective second layer.

[0033] The term "guest material" as used here refers to a material that can modify the electronic properties or emission wavelength of a layer compared to the electronic properties or emission wavelength of the layer without the guest material. The term "host material" as used here refers to a material to which a guest material may or may not be added. The host material may or may not emit light in the absence of the guest material.

[0034] In some embodiments, the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer. For illustration, in one example, the light-emitting layer comprises (iL2-iL1) m, where iL2 denotes a single second layer of the one or more second layers L2, iL1 denotes a single first layer of the one or more first layers L1, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0035] In some embodiments, the light-emitting layer comprises a start layer and a last layer, which are two outermost layers on opposite sides of the light-emitting layer. Optionally, the start layer and the last layer of the light-emitting layer are two second layers of one or more second layers L2. For illustration, in an example, the light-emitting layer comprises (iL2-iL1) m-iL2, where iL2 denotes a single second layer of the one or more second layers L2, iL1 denotes a single first layer of the one or more first layers L1, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0036] In some embodiments, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2. In some embodiments, two adjacent second layers of one or more second layers L2 are separated from each other by a first layer of one or more first layers L1.

[0037] In some embodiments, the weight percentage of the organic functional material of the first type (e.g., the host material) in one or more first layers L1 is in the range of about 40% to about 99% (e.g., 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 95%, or 95% to 100%), and a weight percentage of the organic functional material of the second type (e.g., the guest material) in one or more first layers L1 is in the range of about 1% to about 60% (e.g., 1% to 5%, 5% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, or 50% to 60%). If, in the present disclosure, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2, the problem of concentration annihilation can be avoided.The doping concentration can be much higher without the problem of concentration attenuation occurring. In one example, the weight percentage of the second-type organic functional material (e.g., the guest material) in one or more first layers L1 is in the range of approximately 20% to approximately 50%.

[0038] In some embodiments, the respective first layer and / or the respective second layer can be made with a greater thickness than in the light-emitting diodes concerned. In the light-emitting diodes concerned, a discrete guest material layer is present in which the exciton concentration is relatively high. Therefore, the guest material layer in the corresponding light-emitting diodes must typically be ultrathin, e.g., less than 5 nm. In the present disclosure, the light-emitting diode lacks a discrete guest material layer. The exciton concentration in the one or more first layers L1 is relatively low, so the problem of concentration annihilation does not occur. Accordingly, the one or more first layers L1 and the one or more second layers L2 in the present disclosure can be made with a relatively large thickness, e.g., greater than 5 nm.This results in a relatively simple manufacturing process and improved uniformity in mass production compared to corresponding light-emitting diodes. Furthermore, the inventors of the present disclosure have discovered that superior light emission efficiency and lifetime of the device can be achieved through a combination of several factors, including the values ​​of n and m, the weight percent of the host and guest materials, and the thicknesses of the first and second layers.

[0039] Various suitable first-type organic functional materials (e.g., host materials) can be used within the scope of this disclosure. Examples of first-type organic functional materials include 3-tert-butyl-9,10-di(naphth-2-yl)anthracene, 9,10-di(1-naphthyl)anthracene, 4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl, 1,3,6,8-tetraphenylpyrene, 9,9'-spirobifluorene, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, and 3,3'-bis(N-carbazolyl)-1,1'-biphenyl. Optionally, the guest material is selected from a group consisting of 2,5,8,11-tetra-tert-butylperylene, BCzVBi and 4,4'-[1,4-phenylenedi-(1E)-2,1-ethendiyl]bis[N,N-diphenylbenzenamine].

[0040] In some embodiments, the first-type organic functional material is a bipolar host material. As used here, the term bipolar host material refers to a host material that possesses both hole and electron transport properties. Examples of bipolar host materials are 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline, and 1,3-N,N-dicarbazolebenzene.

[0041] Various suitable second-type organic functional materials (e.g., guest materials) can be used within the scope of this disclosure. Examples of second-type organic functional materials include 2,5,8,11-tetra-tert-butylperylene, BCzVBi, and 4,4'-[1,4-phenylenedi-(1E)-2,1-ethenediyl]bis[N,N-diphenylbenzenamine].

[0042] In some embodiments, the second type of organic functional material is a guest material with high emission efficiency. Examples of guest materials with high emission efficiency include 8-tris-hydroxyquinoline aluminum, tris(2-phenylpyridine)iridium, tris(1-phenylisoquinoline)iridium(III), and bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III).

[0043] Fig. Figure 3 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Referring to Fig. 3 In some embodiments, the light-emitting diode comprises a base substrate BS, an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, a light-emitting layer EL on a side of the hole transport layer HTL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0044] In some embodiments, which relate to Fig. 2 and Fig. As referred to in section 3, any single first layer of one or more first layers L1 is spaced from the hole transport layer HTL or the hole injection layer HIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the hole transport layer HTL or the hole injection layer HIL. This structure prevents any unwanted recombination at an interface between a single first layer and the hole transport layer HTL.

[0045] In some embodiments, which relate to Fig. 2 and Fig. As referred to in section 3, any single first layer of one or more first layers L1 is separated from the electron transport layer ETL or the electron injection layer EIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the electron transport layer ETL or the electron injection layer EIL. This structure prevents any unwanted recombination at an interface between a single first layer and the electron transport layer ETL.

[0046] Various suitable hole transport materials can be used for the fabrication of the hole transport layer (HTL). Examples of suitable hole transport materials include various p-type polymer materials and various low molecular weight p-type materials, e.g., polythiophene, polyaniline, polypyrrole, and a mixture of poly-3,4-ethylenedioxythiophene and poly(sodium p-styrenesulfonate), 4,4'-cyclohexylidene-bis[N,N-bis(4-methylphenyl)benzene] (TAPC), 4,4',4"-tris(N-carbazolyl)triphenylamine (TCTA), N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), or any combination thereof.

[0047] Various suitable injection materials can be used for the fabrication of the HIL (hidden injection layer). Examples of suitable injection materials include poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT:PSS), polythiophene, polyaniline, polypyrrole, copper phthalocyanine, 4,4',4"-tris(N,N-phenyl-3-methylphenylamino)triphenylamine (m-MTDATA), MoO3, and CuPc.

[0048] Various suitable electron injection materials can be used to fabricate the electron injection layer (EIL). Examples of suitable electron injection materials include lithium fluoride and 8-hydroxyquinoline lithium.

[0049] Various suitable electron transport materials can be used to produce the electron transport layer (ETL). Examples of suitable electron transport materials include 4,7-diphenyl-1,10-phenanthroline, 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 8-hydroxyquinoline aluminum, 8-hydroxyquinoline lithium, bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)-aluminium, tris(8-quinolinolate)-aluminium, 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole, bis(10-hydroxybenzo[h]quinolinato-beryllium) and 1,3,5-tris(N-phenylbenzimiazol-2-yl)benzene.

[0050] Various suitable electrode materials and manufacturing processes can be used to fabricate the anode AD. Optionally, the anode AD can be transparent. For example, a non-metallic transparent electrode material can be deposited onto the substrate by plasma-enhanced chemical vapor deposition (PECVD). Examples of suitable non-metallic transparent electrode materials include various transparent metal oxide electrode materials and transparent nanocarbon tubes. Examples of transparent metal oxide materials include indium tin oxide, indium zinc oxide, indium gallium oxide, and indium gallium zinc oxide.

[0051] Various suitable metal electrode materials and manufacturing processes can be used to produce the CD cathode. For example, a metal electrode material can be deposited onto the substrate by plasma-enhanced chemical vapor deposition (PECVD). Examples of suitable metal electrode materials include metals and graphene. Other examples of suitable metal electrode materials include gold, silver, copper, aluminum, magnesium, molybdenum, chromium, neodymium, nickel, manganese, titanium, tantalum, and tungsten.

[0052] Fig. Figure 4 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Referring to Fig. 4. In some embodiments, the light-emitting layer further comprises one or more third layers L3. For example, in some embodiments, the light-emitting layer comprises one or more first layers, one or more second layers, and one or more third layers L3 stacked on top of each other. In some embodiments, each first layer of the one or more first layers L1 comprises an organic functional material of a first type (e.g., a host material) doped with an organic functional material of a second type (e.g., a guest material), and each second layer of the one or more second layers L2 comprises an organic functional material of the first type without doping with an organic functional material of the second type (e.g., a guest material).B, the second-type organic functional material is not present in the respective second layer), and each third layer of the one or more third layers L3 comprises a second-type organic functional material and is free of the first-type organic functional material (e.g., the host material). In an example, each first layer comprises a host material doped with a guest material, each second layer comprises a host material without being doped with a guest material, and each third layer comprises a guest material without having a host material. The dashed line in . Fig. 4 means that the alternating stacked first layer, second layer and third layer can be repeated one or more times.

[0053] In some embodiments, each first layer borders a respective second layer on one side and a respective third layer on the other side. In some embodiments, each first layer is in direct contact with the respective second layer on one side and with the respective third layer on the other side. The light-emitting layer comprises a stacked structure with the respective second layer, the respective first layer on top of the respective second layer, and the respective third layer on a side of the respective first layer opposite the respective second layer.

[0054] In one example, the organic functional materials of the first type are identical in one or more first layers L1. In another example, the organic functional materials of the first type are different in at least two of the one or more first layers L1.

[0055] In one example, the second type of organic functional materials are identical in one or more first layers L1. In another example, the second type of organic functional materials are different in at least two of the one or more first layers L1.

[0056] In one example, the organic functional materials of the first type are identical in one or more second layers L2. In another example, the organic functional materials of the first type differ in at least two of the one or more second layers L2.

[0057] In one example, the second type of organic functional materials are identical in one or more third layers L3. In another example, the second type of organic functional materials differ in at least two of the one or more third layers L3.

[0058] In one example, the organic functional materials of the first type are the same in the respective first layer and in the respective second layer. In another example, the organic functional materials of the first type are different in the respective first layer and in the respective second layer.

[0059] In one example, the organic functional materials of the second type are identical in the respective first and third layers. In another example, the organic functional materials of the second type are different in the respective first and third layers.

[0060] In some embodiments, the light-emitting layer comprises one or more stacked three-layer structures, each three-layer structure comprising a single second layer, a single first layer stacked on top of the single second layer, and a single third layer stacked on a side of the single first layer furthest from the single second layer. For illustration: In one example, the light-emitting layer comprises (iL2-iL1-iL3) m, where iL2 represents a single second layer of one or more second layers L2, iL1 represents a single first layer of one or more first layers L1, iL3 represents a single third layer of one or more third layers L3, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0061] In some embodiments, the light-emitting layer comprises a start layer and a last layer, which are two outermost layers on opposite sides of the light-emitting layer. Optionally, the start layer and the last layer of the light-emitting layer are two second layers of one or more second layers L2. For illustration: In one example, the light-emitting layer comprises (iL2-iL1-iL3) m-iL2, where iL2 represents a single second layer of one or more second layers L2, iL1 represents a single first layer of one or more first layers L1, iL3 represents a single third layer of one or more third layers L3, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0062] In some embodiments, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2 or a third layer of one or more third layers L3. In some embodiments, a single first layer of one or more first layers L1 separates a single second layer of one or more second layers L2 and a single third layer of one or more third layers L3. Optionally, any single first layer of one or more first layers can separate a second layer of one or more second layers and a third layer of one or more third layers.

[0063] In some embodiments, the weight percentage of the organic functional material of the first type (e.g., the host material) in one or more first layers L1 is in the range of about 40% to about 99% (e.g., 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 95%, or 95% to 100%), and a weight percentage of the organic functional material of the second type (e.g., the guest material) in one or more first layers L1 is in the range of about 1% to about 60% (e.g., 1% to 5%, 5% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, or 50% to 60%).If, in the present disclosure, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2 or a third layer of one or more third layers L3, the problem of concentration annihilation can be avoided. The doping concentration can be much higher without the problem of concentration annihilation occurring. In one example, the weight percentage of the second-type organic functional material (e.g., the guest material) in the one or more first layers L1 is in the range of about 20% to about 50%.

[0064] In some embodiments, the respective first layer and / or the respective second layer can have a greater thickness than in the light-emitting diodes in question. In the light-emitting diodes in question, a discrete guest material layer is present in which the exciton concentration is relatively high. Therefore, the guest material layer in the corresponding light-emitting diodes must typically be ultrathin, e.g., less than 5 nm.

[0065] The inventors of the present disclosure have discovered that by spacing the individual first layer of one or more first layers L1 apart from the individual second layer of one or more second layers L2 (host) and the individual third layer of one or more third layers L3 (guest), an energy gap of the charge carriers moving from the individual second layer to the individual third layer or from the individual third layer to the individual second layer can be reduced, thereby making the charge carrier transport through the light-emitting layer smoother, thus improving the light emission intensity and the efficiency of the light-emitting diode.In comparison to the light-emitting layers and light-emitting diodes mentioned above, the light-emitting diode with a single light-emitting layer according to the present disclosure exhibits a larger exciton recombination range, which is due to the presence of the single first layer between the single second layer (host) and the single third layer (guest). In the light-emitting diode according to the present disclosure, the exciton concentration in the light-emitting layer is reduced, thereby preventing concentration quenching and achieving higher light emission efficiency and lifetime of the device.

[0066] Fig. Figure 5 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Referring to Fig. 5 In some embodiments, the light-emitting diode comprises a base substrate BS, an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, a light-emitting layer EL on a side of the hole transport layer HTL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0067] In some embodiments, which relate to Fig. 4 and Fig. As referred to in section 5, any single first layer of one or more first layers L1 is spaced from the hole transport layer HTL or the hole injection layer HIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the hole transport layer HTL or the hole injection layer HIL. This structure prevents any unwanted recombination at an interface between a single first layer and the hole transport layer HTL.

[0068] In some embodiments, which relate to Fig. 4 and Fig. As referred to in section 5, any single first layer of one or more first layers L1 is separated from the electron transport layer ETL or the electron injection layer EIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the electron transport layer ETL or the electron injection layer EIL. This structure prevents any unwanted recombination at an interface between a single first layer and the electron transport layer ETL.

[0069] Fig. Figure 6 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 7 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Referring to Fig. 6 and Fig. 7. In some embodiments, the light-emitting layer comprises one or more first layers and one or more second layers stacked on top of each other. In some embodiments, each first layer of the one or more first layers comprises an organic functional material of a first type (e.g., a host material) doped with an organic functional material of a second type (e.g., a guest material), and each second layer of the one or more second layers comprises an organic functional material of the first type without doping with an organic functional material of the second type; that is, the organic functional material of the second type is not present in the respective second layer. In one example, each first layer comprises a host material doped with a guest material, and each second layer comprises a host material that is not doped with a guest material.

[0070] The light-emitting layer and the light-emitting diode that are in Fig. 6 and Fig. The ones shown in 7 differ from those shown in Fig. 2 and Fig. 3 are shown by the fact that in the light-emitting layer and the light-emitting diode, which are in Fig. 6 and Fig. Figure 7 shows one or more second layers comprising at least one first corresponding second layer L2-1 and one second corresponding second layer L2-2. The first corresponding second layer L2-1 comprises a first organic functional material of the first type without doping a second organic functional material. The second corresponding second layer L2-2 comprises a second organic functional material of the first type without doping a second organic functional material. The first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type. The first organic functional material of the first type differs from the second organic functional material of the first type.

[0071] In one example, the first type-one organic functional material is a p-type type-one organic functional material (e.g., a p-type host material), and the second type-one organic functional material is an n-type type-one organic functional material (e.g., an n-type host material). The term "p-type material" refers to a material that has more positive charge carriers (holes) than negative charge carriers (electrons). The term "n-type material" refers to a material that has more negative charge carriers (electrons) than positive charge carriers (holes).

[0072] In some embodiments, the second corresponding second layer L2-2 is located on a side of the first corresponding second layer L2-1 that is away from the hole transport layer HTL; and the first corresponding second layer L2-1 is located on a side of the second corresponding second layer L2-2 that is away from the electron transport layer ETL.

[0073] The inventor of the present disclosure discovered that hole carriers and electron carriers have different mobility rates. Typically, the hole carriers have a higher mobility rate than the electron carriers. These different mobility rates impair the charge carrier balance, leading to a lower efficiency of exciton recombination.The inventors of the present disclosure have discovered that a more balanced charge carrier transport can be achieved by comprising the first corresponding second layer L2-1 comprising the first organic functional material of the first type and the second corresponding second layer L2-2 comprising the second organic functional material of the first type, wherein the second corresponding second layer L2-2 is located on a side of the first corresponding second layer L2-1 away from the hole transport layer HTL and the first corresponding second layer L2-1 is located on a side of the second corresponding second layer L2-2 away from the electron transport layer ETL.

[0074] In some embodiments, the light-emitting layer and the light-emitting diode comprise the components located in the light-emitting layer. Fig. 6 and Fig. Figure 7 shows one or more first layers, each comprising at least one first corresponding first layer L1-1 and a second corresponding first layer L1-2. The first corresponding first layer L1-1 comprises a first organic functional material of the first type doped with an organic functional material of the second type. The second corresponding first layer L1-2 comprises a second organic functional material of the first type doped with an organic functional material of the second type. The first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type. The first organic functional material of the first type differs from the second organic functional material of the first type.

[0075] In one example, the first type organic functional material is a p-type organic functional material of the first type (e.g., a p-type host material), and the second type organic functional material is an n-type organic functional material of the first type (e.g., an n-type host material).

[0076] In some embodiments, the second corresponding first layer L1-2 is located on a side of the first corresponding first layer L1-1 that is away from the hole transport layer HTL; and the first corresponding first layer L1-1 is located on a side of the second corresponding first layer L1-2 that is away from the electron transport layer ETL.

[0077] In some embodiments, the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer. For illustration: In one example, the light-emitting layer (iL2-iL1) comprises m , where iL2 represents a single second layer of one or more second layers L2, iL1 represents a single first layer of one or more first layers L1, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0078] In some embodiments, the light-emitting layer comprises a start layer and a last layer, which are two outermost layers on opposite sides of the light-emitting layer. Optionally, the start layer and the last layer of the light-emitting layer are two second layers of one or more second layers L2. For illustration: In one example, the light-emitting layer comprises (iL2-iL1) m -iL2, where iL2 represents a single second layer of one or more second layers L2, iL1 represents a single first layer of one or more first layers L1, and m is an integer equal to or greater than 1, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0079] In some embodiments, m is an integer equal to or greater than 2. The light-emitting layer comprises (iL2-1-iL1-1)-(iL2-iL1) (m-1)-iL2-2, where iL2 represents a single second layer of one or more second layers L2, iL1 represents a single first layer of one or more first layers L1, iL2-1 represents a single first corresponding second layer, iL2-2 represents a single second corresponding second layer, and m is an integer equal to or greater than 2. Optionally, the -(iL2-iL1) (m-1) - also include one or more additional first corresponding second layers and / or one or more additional second corresponding second layers.

[0080] In some embodiments, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2. In some embodiments, two adjacent second layers of one or more second layers L2 are separated from each other by a first layer of one or more first layers L1.

[0081] In some embodiments, the weight percentage of the organic functional material of the first type (e.g., the host material) in one or more first layers L1 is in the range of about 40% to about 99% (e.g., 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 95%, or 95% to 100%), and a weight percentage of the organic functional material of the second type (e.g., the guest material) in one or more first layers L1 is in the range of about 1% to about 60% (e.g., 1% to 5%, 5% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, or 50% to 60%). In one example, the weight percentage of the second type of organic functional material (e.g., the guest material) in one or more first layers L1 is in the range of about 20% to about 50%.

[0082] Referring to Fig. 7 In some embodiments, the light-emitting diode comprises a base substrate BS, an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, a light-emitting layer EL on a side of the hole transport layer HTL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0083] In some embodiments, which relate to Fig. 6 and Fig. As referred to in section 7, any single first layer of one or more first layers L1 is spaced from the hole transport layer HTL or the hole injection layer HIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the hole transport layer HTL or the hole injection layer HIL. This structure prevents any unwanted recombination at an interface between a single first layer and the hole transport layer HTL.

[0084] In some embodiments, which relate to Fig. 6 and Fig. As referred to in section 7, any single first layer of one or more first layers L1 is separated from the electron transport layer ETL or the electron injection layer EIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the electron transport layer ETL or the electron injection layer EIL. This structure prevents any unwanted recombination at an interface between a single first layer and the electron transport layer ETL.

[0085] Fig. Figure 8 is a schematic representation showing the structure of a light-emitting layer in some embodiments according to the present disclosure. Fig. Figure 9 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Referring to Fig. 8 and Fig. 9 In some embodiments, the light-emitting layer comprises one or more first layers L1 and one or more second layers L2 stacked on top of each other. In some embodiments, each first layer of the one or more first layers L1 comprises an organic functional material of a first type (e.g., a host material) doped with an organic functional material of a second type (e.g., a guest material), and each second layer of the one or more second layers L2 comprises an organic functional material of the first type without doping with an organic functional material of the second type; that is, the organic functional material of the second type is not present in the respective second layer.In one example, the respective first layer comprises a host material doped with a guest material, and the respective second layer comprises a host material that is not doped with a guest material.

[0086] In some embodiments, the one or more first layers L1 comprise a first corresponding first layer L1-1, a second corresponding first layer L1-2, and a third corresponding first layer L1-3. The first corresponding first layer L1-1, the second corresponding first layer L1-2, and the third corresponding first layer L1-3 are first layers of different colors. For example, the first corresponding first layer L1-1 is a first layer of a first color, the second corresponding first layer L1-2 is a first layer of a second color, and the third corresponding first layer L1-3 is a first layer of a third color. In one example, the first color, the second color, and the third color are three different colors selected from red, green, and blue.

[0087] In some embodiments, the one or more first layers L1 further comprise one or more fourth corresponding first layers L1-4. Optionally, the one or more fourth corresponding first layer(s) L1-4 lie at least partially outside an exciton recombination region of the light-emitting layer EL. Optionally, the one or more fourth respective first layers L1-4 lie completely outside an exciton recombination region of the light-emitting layer EL.

[0088] In some embodiments, the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer. For illustration, in one example, the light-emitting layer comprises (iL2-iL1-1)-(iL2-iL1-2)-(iL2-iL1-3), where iL2 represents a single second layer of the one or more second layers L2, iL1-1 represents a single first corresponding first layer, iL1-2 represents a single second corresponding first layer, and iL1-3 represents a single third corresponding first layer.Optionally, the light-emitting layer comprises a first bilayer structure comprising a first single second layer and the first corresponding first layer on the first single second layer; a second bilayer structure comprising a second single second layer and the second corresponding first layer on the second single second layer; and a third bilayer structure comprising a third single second layer and the third corresponding first layer on the third single second layer. Optionally, the third bilayer structure is located on a side of the second bilayer structure opposite the first bilayer structure. Optionally, the first single second layer, the second single second layer, and the third single second layer are distinct layers.Optionally, the first corresponding first layer, the second corresponding first layer, and the third corresponding first layer can be different layers.

[0089] In some embodiments, the light-emitting layer comprises a start layer and a last layer, which are two outermost layers on opposite sides of the light-emitting layer. Optionally, the start layer and the last layer of the light-emitting layer are two second layers of one or more second layers L2. For illustration: In one example, the light-emitting layer comprises (iL2-iL1-4)-(iL2-iL1-1)-(iL2-iL1-2)-(iL2-iL1-3)-(iL2-iL1-4)-iL2, where iL2 represents a single second layer of one or more second layers L2, iL1-1 represents a single first corresponding first layer, iL1-2 represents a single second corresponding first layer, iL1-3 represents a single third corresponding first layer, and iL1-4 represents a single fourth corresponding first layer.Optionally, the light-emitting layer comprises a first bilayer structure comprising a first single second layer and the fourth corresponding first layer on the first single second layer, a second bilayer structure comprising a second single second layer and the first corresponding first layer on the second single second layer, a third bilayer structure comprising a third single second layer and the second corresponding first layer on the third single second layer, a fourth bilayer structure comprising a fourth single second layer and the third corresponding first layer on the fourth single second layer, and the last layer.Optionally, the third double-layer structure is located on a side of the second double-layer structure furthest from the first double-layer structure, and the fourth double-layer structure is located on a side of the third double-layer structure furthest from the second double-layer structure.

[0090] In some embodiments, two adjacent first layers of one or more first layers L1 are separated from each other by a second layer of one or more second layers L2. In some embodiments, two adjacent second layers of one or more second layers L2 are separated from each other by a first layer of one or more first layers L1.

[0091] In some embodiments, the weight percentage of the organic functional material of the first type (e.g., the host material) in one or more first layers L1 is in the range of about 40% to about 99% (e.g., 40% to 50%, 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 95%, or 95% to 100%), and a weight percentage of the organic functional material of the second type (e.g., the guest material) in one or more first layers L1 is in the range of about 1% to about 60% (e.g., 1% to 5%, 5% to 10%, 10% to 20%, 20% to 30%, 30% to 40%, 40% to 50%, or 50% to 60%). In one example, the weight percentage of the second type of organic functional material (e.g., the guest material) in one or more first layers L1 is in the range of about 20% to about 50%.

[0092] Referring to Fig. 9 In some embodiments, the light-emitting diode comprises a base substrate BS, an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, a light-emitting layer EL on a side of the hole transport layer HTL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0093] In some embodiments, which relate to Fig. 8 and Fig. As referred to in section 9, any single first layer of one or more first layers L1 is spaced from the hole transport layer HTL or the hole injection layer HIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the hole transport layer HTL or the hole injection layer HIL. This structure prevents any unwanted recombination at an interface between a single first layer and the hole transport layer HTL.

[0094] In some embodiments, which relate to Fig. 8 and Fig. As referred to in section 9, any single first layer of one or more first layers L1 is separated from the electron transport layer ETL or the electron injection layer EIL by at least one second layer of one or more second layers L2. Any single first layer of one or more first layers L1 is not in direct contact with the electron transport layer ETL or the electron injection layer EIL. This structure prevents any unwanted recombination at an interface between a single first layer and the electron transport layer ETL.

[0095] By locating the first corresponding first layer L1-1, the second corresponding first layer L1-2, and the third corresponding first layer L1-3 at least partially within an exciton recombination region of the light-emitting layer EL, a white color image display can be achieved. The first corresponding first layer L1-1, the second corresponding first layer L1-2, and the third corresponding first layer L1-3 can have different thicknesses and / or doping percentages, thus realizing a true white light display.

[0096] In some embodiments, the present disclosure further provides a method for determining an exciton recombination region of the light-emitting layer. Fig. 10A to Fig. Figure 10E illustrates a method for determining an exciton recombination region in a light-emitting layer in some embodiments according to the present disclosure. Referring to Fig. 10A to Fig. 10E comprises one or more first layers L1, a plurality of fourth respective first layers (each fourth corresponding first layer is designated L1-4), and each first test layer L1-t. The respective first test layer L1-t can be a first layer of a specific color. For example, the first test layer L1-t can be a first layer configured to emit red light. For the in Fig. An emission spectrum is recorded for the light-emitting diode shown in diagram 10A. If a red-light emission peak is detected in the emission spectrum, this indicates that the first layer L1-t under test is at least partially located in the exciton recombination region. If no red-light emission peak is detected in the emission spectrum, this indicates that the first layer L1-t under test is at least partially located outside the exciton recombination region. Fig. 10A to Fig. In 10E, the first layer L1-t to be tested is located at different positions on the light-emitting diode. In one example, in the one described in Fig. 10A and Fig. No red light emission peak was detected in the emission spectrum recorded by the light-emitting diodes shown in 10E, whereas in the spectrum shown by the in Fig. 10B, Fig. 10C and Fig. In the emission spectrum of the light-emitting diodes shown in 10D, a red-light emission peak is observed. This indicates that the second, third, and fourth layers of the one or more first layers L1 are at least partially located within the exciton recombination region of the light-emitting diode, and that the first and last layers of the one or more first layers L1 are at least partially located outside the exciton recombination region of the light-emitting diode.

[0097] In some embodiments, the light-emitting diode comprises a plurality of light-emitting layers. Fig. Figure 11 is a schematic representation showing the structure of a light-emitting diode in some embodiments according to the present disclosure. Referring to Fig. 11 In some embodiments, the light-emitting diode is a tandem light-emitting diode with a first light-emitting layer EL1 and a second light-emitting layer EL2 stacked on top of each other. The first light-emitting layer EL1 can be one of the light-emitting layers described in the present disclosure, for example, those described in Fig. 2, Fig. 4, Fig. 6 or Fig. 8 light-emitting layer shown. The second light-emitting layer, EL2, can be any of the light-emitting layers described in the present disclosure, for example, the one shown in Fig. 2, Fig. 4, Fig. 6 or Fig. 8 light-emitting layer shown.

[0098] In some embodiments, the light-emitting diode comprises a base substrate BS, an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a first hole transport layer HTL1 on a side of the hole injection layer HIL1 furthest from the base substrate BS, a first light-emitting layer EL1 on a side of the first hole transport layer HTL furthest from the base substrate BS, a first electron transport layer ETL1 on a side of the first light-emitting layer EL1 furthest from the base substrate BS, a charge generation layer CGL on a side of the first electron transport layer ETL furthest from the base substrate BS, a second hole transport layer HTL2 on a side of the charge generation layer CGL furthest from the base substrate BS, and a second light-emitting layer EL2 on a side of the second hole transport layer HTL2 furthest from the base substrate BS.a second electron transport layer ETL2 on a side of the second light-emitting layer EL2 furthest from the base substrate BS, an electron injection layer EIL on a side of the second electron transport layer ETL2 furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0099] In some embodiments, the charge-generating layer CGL comprises an n-doped layer and a p-doped layer on the side of the n-doped layer furthest from the base substrate BS. The n-doped layer and the p-doped layer are directly connected to each other, forming a pn junction. A depletion region forms in the pn junction, where electrons migrate from the n-doped layer into the p-doped layer.

[0100] The inventors of the present disclosure discovered that the n-doped layer typically comprises metallic elements such as alkali metal compounds and / or metal. These metallic elements tend to volatilize into the p-doped layer and / or adjacent organic layers, leading to interface degradation and quenching of the light-emitting molecules. This often results in reduced light emission efficiency and a shorter lifetime of the device.

[0101] The inventors of the present disclosure have discovered that the light-emitting layer (e.g., the first light-emitting layer EL1 and the second light-emitting layer EL2) circumvents this problem by arranging the one or more first layers and the one or more second layers alternately. This unique structure of the present light-emitting layer effectively prevents the metal elements from migrating into layers in the exciton recombination region, thereby significantly increasing the light emission efficiency and the lifetime of the device.

[0102] Various suitable n-doped materials can be used to fabricate the n-doped layer. Various suitable p-doped materials can be used to fabricate the p-doped layer. Both the n-doped and p-doped layers can contain one or more organic and / or inorganic materials as a matrix. The matrix is ​​modified with one or more organic or inorganic dopants to increase its conductivity. Examples of dopants for the n-doped layer include metals with a low work function, such as Na, Ca, Cs, Li, Mg, or their compounds, such as Cs₂CO₃, Cs₃PO₄, or organic dopants such as NDN-1, NDN-26. Examples of dopants for the p-doped layer include transition metal oxides, such as MoOx, WOx, VOx, and organic compounds. B. Cu(I)pFBz, F4-TCNQ, or organic dopants such as NDP-2, NDP-9.

[0103] In one example, the n-doped layer comprises Bepp2:Li. Optionally, the Li doping concentration is 5%.

[0104] In one example, the p-doped layer comprises NPB:HAT-CN. Optionally, the doping concentration of HAT-CN is 10%.

[0105] In another aspect, the present disclosure provides a display substrate comprising the light-emitting diode described herein or produced by a method described herein and a pixel driver circuit configured to drive the light emission of the light-emitting diode.

[0106] Fig. Figure 12 is a schematic representation showing the structure of a display substrate in some embodiments according to the present disclosure. Referring to Fig. 12 In some embodiments, the display substrate comprises a base substrate BS; an active layer ACT of a plurality of thin-film transistors TFT on the base substrate BS; a gate insulating layer GI on a side of the active layer ACT furthest from the base substrate BS; a gate electrode G and a first capacitor electrode Ce1 (both being parts of a first gate metal layer) on a side of the gate insulating layer GI furthest from the base substrate BS; an insulating layer IN on a side of the gate electrode G and the first capacitor electrode Ce1 furthest from the gate insulating layer GI; a second capacitor electrode Ce2 (part of a second gate metal layer) on a side of the insulating layer IN furthest from the gate insulating layer GI; a dielectric intermediate layer ILD on a side of the second capacitor electrode Ce2 furthest from the gate insulating layer GI;a source electrode S and a drain electrode D (parts of a first SD metal layer) on one side of the dielectric intermediate layer ILD away from the gate insulating layer GI; a passivation layer PVX on one side of the source electrode S and the drain electrode D away from the dielectric intermediate layer ILD; a first planarization layer PLN1 on one side of the passivation layer PVX away from the dielectric intermediate layer ILD; a relay electrode RE (part of a second SD metal layer) on one side of the first planarization layer PLN1 away from the passivation layer PVX; a second planarization layer PLN2 on one side of the relay electrode RE away from the first planarization layer PLN1; a pixel definition layer PDL, which defines a subpixel aperture, and on one side of the second planarization layer PLN2 away from the base substrate BS;and a light-emitting diode LE in the subpixel aperture. The light-emitting diode LE comprises an anode AD on the base substrate BS, a hole injection layer HIL on a side of the anode AD furthest from the base substrate BS, a hole transport layer HTL on a side of the hole injection layer HIL furthest from the base substrate BS, a light-emitting layer EL on a side of the hole transport layer HTL furthest from the base substrate BS, an electron transport layer ETL on a side of the light-emitting layer EL furthest from the base substrate BS, an electron injection layer EIL on a side of the electron transport layer ETL furthest from the base substrate BS, and a cathode CD on a side of the electron injection layer EIL furthest from the base substrate BS.

[0107] The display substrate in the display area further comprises an encapsulation layer EN, which encapsulates the light-emitting element LE on a side of the cathode CD furthest from the base substrate BS. In some embodiments, the encapsulation layer EN comprises a first inorganic encapsulation sublayer CVD1 on a side of the cathode CD furthest from the base substrate BS, an organic encapsulation sublayer IJP on a side of the first inorganic encapsulation sublayer CVD1 furthest from the base substrate BS, and a second inorganic encapsulation sublayer CVD2 on a side of the organic encapsulation sublayer IJP furthest from the base substrate BS.

[0108] In some embodiments, the display substrate also comprises a touch structure TS. In some embodiments, the touch structure TS comprises a buffer layer BUF on a side of the encapsulation layer EN furthest from the base substrate BS; a first touch electrode layer TE1 on a side of the buffer layer BUF furthest from the encapsulation layer EN; a touch insulating layer TI on a side of the first touch electrode layer TE1 furthest from the buffer layer BUF; a second touch electrode layer TE2 on a side of the touch insulating layer TI furthest from the buffer layer BUF; and a coating layer OC on a side of the second touch electrode layer TE2 furthest from the touch insulating layer TI.

[0109] Fig. Figure 13 is a circuit diagram illustrating the structure of a pixel driver circuit in some embodiments according to the present disclosure. Referring to Fig.13 In some embodiments, the respective pixel driver circuit comprises a driver transistor Td; a storage capacitor Cst with a first capacitor electrode Ce1 and a second capacitor electrode Ce2; a first transistor T1 with a gate electrode connected to a respective reset control signal line rstN in a current stage (or current series) of a plurality of reset control signal lines, a first electrode connected to a respective first reset signal line Vint1N in a current stage (or current series) of a plurality of first reset signal lines, and a second electrode connected to a first capacitor electrode Ce1 of the storage capacitor Cst and a gate electrode of the driver transistor Td;a second transistor T2 with a gate electrode connected to a respective gate line of a plurality of gate lines GL, a first electrode connected to a respective data line of a plurality of data lines DL, and a second electrode connected to a first electrode of the driver transistor Td; a third transistor T3 with a gate electrode connected to the respective gate line, a first electrode connected to the first capacitor electrode Ce1 of the storage capacitor Cst and the gate electrode of the driver transistor Td, and a second electrode connected to a second electrode of the driver transistor Td;a fourth transistor T4 with a gate electrode connected to a respective light emission control signal line of a plurality of light emission control signal lines em, a first electrode connected to a respective voltage supply line of a plurality of voltage supply lines Vdd, and a second electrode connected to the first electrode of the driver transistor Td and the second electrode of the second transistor T2; a fifth transistor T5 with a gate electrode connected to the respective light-emitting control signal line, a first electrode connected to the second electrodes of the driver transistor Td and the third transistor T3, and a second electrode connected to an anode of a light-emitting element LE;and a sixth transistor T6 with a gate electrode connected to a respective reset control signal line rst(N+1) in the next adjacent stage (or next adjacent row) of a plurality of reset control signal lines, a first electrode connected to a respective second reset signal line Vint2N in the current stage (or current row) of the plurality of second reset signal lines, and a second electrode connected to the second electrode of the fifth transistor and the anode of the light-emitting element LE. The second capacitor electrode Ce2 is connected to the respective power supply line and the first electrode of the fourth transistor T4.

[0110] In another aspect, the present disclosure provides a display device comprising the display substrate described herein or produced by a method described herein, and one or more integrated circuits connected to the display substrate. Examples of suitable display devices include, but are not limited to, electronic paper, a mobile phone, a tablet computer, a television, a monitor, a notebook, a digital album, a GPS, etc. Optionally, the display device is an organic light-emitting diode display device. Optionally, the display device is a miniature light-emitting diode display device. Optionally, the display device is a quantum dot light-emitting diode display device.

[0111] In another aspect, the present disclosure provides a method for producing a light-emitting diode. In some embodiments, the method includes the formation of a light-emitting layer. Optionally, the formation of the light-emitting layer includes the formation of one or more first layers and the formation of one or more second layers in a stacked structure. Optionally, each first layer of the one or more first layers comprises an organic functional material of a first type doped with an organic functional material of a second type. Optionally, each second layer of the one or more second layers comprises an organic functional material of the first type without doping with an organic functional material of the second type.Optionally, the formation of the light-emitting layer includes the formation of one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer.

[0112] The foregoing description of the embodiments of the invention has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the invention to the exact form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than limiting. Naturally, many modifications and variations are obvious to those skilled in the art. The embodiments have been selected and described to explain the principles of the invention and its best possible practical application, and to enable those skilled in the art to understand the invention in various embodiments and with various modifications suitable for the respective use or implementation.It is intended that the scope of the invention be defined by the appended claims and their equivalents, in which all terms are meant in their broadest meaningful sense unless otherwise specified. Therefore, the term "the invention," "the present invention," or the like does not necessarily imply a limitation of the scope of the claims to a particular embodiment, and reference to exemplary embodiments of the invention does not imply a limitation of the invention, nor can such a limitation be inferred. The invention is limited only by the spirit and scope of the appended claims. Furthermore, reference may be made in these claims to the use of "first," "second," etc., following a noun or element.These terms are to be understood as a nomenclature and should not be interpreted as limiting the number of elements modified by this nomenclature unless a specific number has been indicated. All described advantages and benefits may not apply to all embodiments of the invention. A person skilled in the art may modify the described embodiments without departing from the scope of the present invention as defined by the following claims. Furthermore, no element or component in the present disclosure is intended to be disclosed to the public, regardless of whether the element or component is expressly mentioned in the following claims.

Claims

[1] Light-emitting diode comprising a light-emitting layer; wherein the light-emitting layer comprises one or more first layers and one or more second layers in a stacked structure; a respective first layer of one or more first layers comprises an organic functional material of a first type, which is doped with an organic functional material of a second type; Each second layer of one or more second layers comprises an organic functional material of the first type without doping an organic functional material of the second type; wherein the light-emitting layer comprises one or more stacked bilayer structures, each bilayer structure comprising a single second layer and a single first layer stacked on top of the single second layer. [2] Light-emitting diode according to claim 1, wherein the light-emitting layer comprises a starting layer and a last layer, which are two outermost layers on two sides of the light-emitting layer; and the starting layer and the last layer of the light-emitting layer are two second layers of one or more second layers. [3] Light-emitting diode according to claim 1, wherein two adjacent first layers of one or more first layers are spaced apart from each other by a second layer of one or more second layers; and two adjacent second layers of one or more second layers are spaced apart from each other by a first layer of one or more first layers. [4] Light-emitting diode according to claim 1, wherein a weight percentage of the second type of organic functional material in one or more first layers is in a range of about 20% to about 50%. [5] Light-emitting diode according to claim 1, further comprising a hole transport layer and an electron transport layer; wherein any single first layer of the one or more first layers is spaced from the hole transport layer by at least one second layer of the one or more second layers; and any single first layer of one or more first layers is spaced from the electron transport layer by at least one second layer of one or more second layers. [6] Light-emitting diode according to claim 1, wherein the light-emitting layer further comprises one or more third layers; wherein the one or more first layers, the one or more second layers and the one or more third layers are in the stacked structure; and Each third layer of one or more third layers comprises an organic functional material of the second type and does not comprise an organic functional material of the first type. [7] Light-emitting diode according to claim 6, wherein the respective first layer is in direct contact on one side with the respective second layer and on the other side with a respective third layer; and the light-emitting layer comprises one or more three-layer structures in the stacked structure, wherein a respective three-layer structure of the one or more three-layer structures comprises a single second layer, a single first layer stacked on the single second layer, and a single third layer stacked on a side of the single first layer away from the single second layer. [8] Light-emitting diode according to claim 6, wherein two adjacent first layers of one or more first layers are spaced apart from each other by a second layer of one or more second layers or a third layer of one or more third layers; and any single first layer of one or more first layers spaced apart from a second layer of one or more second layers and from a third layer of one or more third layers. [9] Light-emitting diode according to claim 1, wherein the one or more second layers comprise at least one first corresponding second layer and one second corresponding second layer; the first corresponding second layer comprises a first organic functional material of the first type, without doping an organic functional material of the second type; the second corresponding second layer comprises a second organic functional material of the first type, without doping an organic functional material of the second type; the first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type; and The first organic functional material of the first type differs from the second organic functional material of the first type. [10] Light-emitting diode according to claim 9, wherein the first organic functional material of the first type is a p-type organic functional material of the first type; and the second organic functional material of the first type is an n-type organic functional material of the first type. [11] Light-emitting diode according to claim 9, wherein the second corresponding second layer is located on a side of the first corresponding second layer away from a hole transport layer; and the first corresponding second layer is located on a side of the second corresponding second layer away from an electron transport layer. [12] Light-emitting diode according to claim 1, wherein the one or more first layers comprise at least one first corresponding first layer and a second corresponding first layer; the first corresponding first layer comprises a first organic functional material of the first type, which is doped with an organic functional material of the second type; the second corresponding first layer comprises a second organic functional material of the first type, which is doped with an organic functional material of the second type; the first organic functional material of the first type and the second organic functional material of the first type are both organic functional materials of the first type; and The first organic functional material of the first type differs from the second organic functional material of the first type. [13] Light-emitting diode according to claim 12, wherein the first organic functional material of the first type is a p-type organic functional material of the first type; and the second organic functional material of the first type is an n-type organic functional material of the first type. [14] Light-emitting diode according to claim 12, wherein the second corresponding first layer is located on a side of the first corresponding first layer away from a hole transport layer; and the first corresponding first layer is located on a side of the second corresponding first layer away from an electron transport layer. [15] Light-emitting diode according to claim 1, wherein the one or more first layers comprise a first corresponding first layer, a second corresponding first layer and a third corresponding first layer; the first corresponding first layer is a first layer of a first color; the second corresponding first layer is a first layer of a second color; the third corresponding first layer is a first layer with a third color; and The first color, the second color, and the third color are three different colors. [16] Light-emitting diode according to claim 15, wherein the one or more first layers further comprise one or more fourth corresponding first layers which lie at least partially outside an exciton recombination region of the light-emitting layer. [17] Light-emitting diode according to claim 15, wherein the light-emitting layer comprises: a first bilayer structure comprising a first single second layer and the first corresponding first layer on top of the first single second layer; a second bilayer structure comprising a second single second layer and the second corresponding first layer on top of the second single second layer; and a third double-layer structure comprising a third single second layer and the third corresponding first layer on top of the third single second layer; wherein the third bilayer structure is located on a side of the second bilayer structure furthest from the first bilayer structure; the first single second layer, the second single second layer, and the third single second layer are distinct layers; and The first corresponding first layer, the second corresponding first layer, and the third corresponding first layer are different layers. [18] Light-emitting diode according to claim 15, wherein the light-emitting layer comprises: a first double-layer structure comprising a first single second layer and a fourth corresponding first layer on top of the first single second layer; a second double-layer structure comprising a second single second layer and the first corresponding first layer on top of the second single second layer; a third double-layer structure comprising a third single second layer and the second corresponding first layer on top of the third single second layer; a fourth bilayer structure comprising a fourth single second layer and the third corresponding first layer on top of the fourth single second layer; and a final layer, which is one of one or more second layers; wherein the third bilayer structure is located on a side of the second bilayer structure away from the first bilayer structure, and the fourth bilayer structure is located on a side of the third bilayer structure away from the second bilayer structure. [19] Light-emitting diode according to claim 1, comprising: a first light-emitting layer; a charge-generating layer on the first light-emitting layer; and a second light-emitting layer on a side of the charge-generating layer farther from the first light-emitting layer; wherein the charge-generating layer comprises an n-doped layer and a p-doped layer on a side of the n-doped layer away from the first light-emitting layer. [20] Display device comprising the light-emitting diode according to any one of claims 1 to 19 and a pixel driver circuit configured to drive the light emission of the light-emitting diode.

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