Organic light-emitting device, display panel, preparation method and display device

Abstract

The invention provides an organic light-emitting device, a display panel, a preparation method and a display device. The organic light-emitting device comprises an anode layer, a light-emitting layer and a cathode layer which are sequentially stacked; wherein the light-emitting layer comprises a host material, a sensitizer and a dye; the sensitizer and the dye are doped in the main body material, and in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer is reduced, and the doping concentration of the dye is increased. According to the technical scheme, the service life and the luminous efficiency of the organic electroluminescent device can be improved.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to an organic light emitting device, a display panel and a manufacturing method thereof, and a display device. Background Art

[0002] An organic light emitting diode (OLED) is a device that emits light through current driving. Specifically, an organic light emitting device includes functional layers such as a cathode layer, an anode layer, and a light emitting layer located between the cathode layer and the anode layer. When a voltage is applied, electrons from the cathode layer and holes from the anode layer will migrate to the light emitting layer and combine to generate excitons, and then emit light of different wavelengths according to the characteristics of the light emitting layer. However, currently, there are still some problems with organic light emitting devices. Summary of the Invention

[0003] To solve the above problems, embodiments of this application provide an organic light emitting device, a display panel and a manufacturing method thereof, and a display device.

[0004] In a first aspect, embodiments of this application provide an organic light emitting device, including: an anode layer, a light emitting layer, and a cathode layer that are sequentially stacked; wherein, the light emitting layer includes a host material, a sensitizer, and a dye; the sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases, and the doping concentration of the dye increases.

[0005] In combination with the first aspect, the doping concentration gradient of the sensitizer decreases, and / or the doping concentration gradient of the dye increases; preferably, the sensitizer includes a phosphorescent sensitizer, and the dye includes a fluorescent light emitting material; preferably, the host material includes a thermally activated delayed fluorescence material; preferably, the thickness range of the light emitting layer is 15nm to 60nm.

[0006] In combination with the first aspect, in the direction from the anode layer to the cathode layer, the doping concentration range of the sensitizer is 0.5% to 15%; and / or, the doping concentration range of the dye is 0.3% to 3%; preferably, the doping concentration range of the sensitizer is 5% to 15%, preferably, the doping concentration range of the sensitizer is 0.5% to 5%; and / or, preferably, the doping concentration range of the dye is 1.5% to 3.0%, preferably, the doping concentration range of the dye is 0.3% to 1.5%.

[0007] In combination with the first aspect, the organic electroluminescent device further includes: a hole transport region and an electron transport region. The hole transport region is located between the anode layer and the light-emitting layer, and the electron transport region is located between the cathode layer and the light-emitting layer; preferably, the hole transport region includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer; preferably, the electron transport region includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

[0008] An embodiment of the present application further provides an electroluminescent device, including an anode layer, at least two stacked light-emitting layers and a cathode layer stacked in sequence, and at least one light-emitting layer is the light-emitting layer mentioned above.

[0009] An embodiment of the present application further provides a display panel, including: a substrate and any one of the organic electroluminescent devices mentioned above, and the organic electroluminescent device is located on the substrate.

[0010] In combination with the third aspect, the organic electroluminescent device includes an anode layer, a light-emitting layer, and a cathode layer stacked in sequence along the direction away from the substrate. The display panel further includes: a light extraction layer, and the light extraction layer is located on the side of the cathode layer away from the substrate; preferably, the refractive index range of the material of the light extraction layer is 1.7 to 2.2; preferably, the thickness range of the light extraction layer is 50 to 80 nm.

[0011] An embodiment of the present application further provides a method for manufacturing a display panel, including: preparing an anode layer on a substrate; preparing a light-emitting layer on the side of the anode layer away from the substrate, and the light-emitting layer includes a host material, a sensitizer, and a dye; the sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the light-emitting layer, the doping concentration of the sensitizer decreases, and the doping concentration of the dye increases; preparing a cathode layer on the side of the light-emitting layer away from the substrate.

[0012] In combination with the fourth aspect, a light-emitting layer is prepared on the side of the anode layer facing away from the substrate, including: placing the host material, sensitizer, and dye in different evaporation sources respectively, changing the doping concentration of the sensitizer by changing the evaporation rate of the sensitizer, changing the doping concentration of the dye by changing the evaporation rate of the dye, and achieving stable evaporation of the host material by stabilizing the evaporation rate of the host material; preferably, the evaporation rate of the sensitizer is changed by controlling the evaporation temperature of the evaporation source where the sensitizer is placed, and the evaporation rate of the dye is changed by controlling the evaporation temperature of the evaporation source where the dye is placed; preferably, as the evaporation time changes, the evaporation rate of the sensitizer decreases and the evaporation rate of the dye increases; preferably, before the step of preparing the light-emitting layer on the side of the anode layer facing away from the substrate, the preparation method further includes: sequentially preparing a hole injection layer, a hole transport layer, and an electron blocking layer on the side of the anode layer facing away from the substrate; preferably, after the step of preparing the light-emitting layer on the side of the anode layer facing away from the substrate, the preparation method further includes: sequentially preparing a hole blocking layer, an electron transport layer, and an electron injection layer on the side of the light-emitting layer facing away from the substrate; preferably, the hole injection layer, the hole transport layer, and the electron blocking layer are prepared by an evaporation process; and / or, the hole blocking layer, the electron transport layer, and the electron injection layer are prepared by an evaporation process; preferably, the preparation method further includes: preparing a light extraction layer on the side of the cathode layer facing away from the substrate.

[0013] An embodiment of the present application further provides a display device, including the display panel mentioned above, or including the display panel prepared by the preparation method mentioned above.

[0014] The organic electroluminescent device, display panel, preparation method, and display device provided by the present application, the organic electroluminescent device includes: an anode layer, a light-emitting layer, and a cathode layer stacked in sequence; wherein, the light-emitting layer includes a host material, a sensitizer, and a dye; the sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases and the doping concentration of the dye increases. In the light-emitting layer, in the region with a relatively high doping concentration of the sensitizer, a large amount of sensitizers make full use of the exciton energy and transfer this part of the exciton energy to the dye, improving the light-emitting efficiency of the organic electroluminescent device; and in the region with a relatively high doping concentration of the sensitizer, the doping concentration of the dye is relatively low, reducing the Dexter energy transfer probability, reducing the concentration of high-energy triplet excitons, and reducing the probability of deterioration of the light-emitting layer material caused by triplet-triplet annihilation (TTA), thereby improving the lifespan of the organic electroluminescent device. In the light-emitting layer, in the region with a relatively low doping concentration of the sensitizer, the doping concentration of the dye is relatively high, and a large amount of dyes can ensure the light-emitting efficiency of this region of the light-emitting layer. Description of the Drawings

[0015] Figure 1It is a schematic structural diagram of an organic electroluminescent device provided by the first embodiment of the present application.

[0016] Figure 2 It is a partial schematic structural diagram of an organic electroluminescent device provided by the first embodiment of the present application.

[0017] Figure 3 It is a partial schematic structural diagram of an organic electroluminescent device provided by the second embodiment of the present application.

[0018] Figure 4 It is a partial schematic structural diagram of an organic electroluminescent device provided by the third embodiment of the present application.

[0019] Figure 5 It is a partial schematic structural diagram of an organic electroluminescent device provided by the fourth embodiment of the present application.

[0020] Figure 6 It is a partial schematic structural diagram of an organic electroluminescent device provided by the fifth embodiment of the present application.

[0021] Figure 7 It is a partial schematic structural diagram of an organic electroluminescent device provided by the sixth embodiment of the present application.

[0022] Figure 8 It is a partial schematic structural diagram of an organic electroluminescent device provided by the seventh embodiment of the present application.

[0023] Figure 9 It is a partial schematic structural diagram of an organic electroluminescent device provided by the eighth embodiment of the present application.

[0024] Figure 10 It is a partial schematic structural diagram of an organic electroluminescent device provided by the ninth embodiment of the present application.

[0025] Figure 11 It is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of the present application.

[0026] Figure 12 It is a schematic structural diagram of a display panel provided by an embodiment of the present application.

[0027] Figure 13 It is a schematic flowchart of a method for manufacturing a display panel provided by an embodiment of the present application.

[0028] Figure 14 It is a distribution diagram of exciton recombination regions in the light-emitting layers of red, green, and blue organic electroluminescent devices.

[0029] Figure 15 It is a schematic structural diagram of a display device provided by an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 100 organic electroluminescent device; 110 anode layer; 120 light-emitting layer; 121 host material; 122 sensitizer; 123 dye; 130 cathode layer; 140 hole transport region; 141 hole injection layer; 142 hole transport layer; 143 electron blocking layer; 150 electron transport region; 151 electron injection layer; 152 electron transport layer; 153 hole blocking layer; 200 display panel; 210 substrate; 220 light extraction layer; 1100 display device. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] In the art, the distribution of excitons in the light-emitting layer is not uniform, and there is a problem that the capacity of the excitons in the light-emitting layer cannot be fully utilized.

[0034] The present application provides an organic electroluminescent device, comprising: an anode layer, a light-emitting layer (Element Management Layer, EML), and a cathode layer stacked in sequence. The light-emitting layer comprises a host material, a sensitizer, and a dye. The sensitizer and the dye are doped into the host material in a gradient doping concentration manner; the gradient direction of the sensitizer's doping concentration is opposite to the gradient direction of the dye's doping concentration. The gradient doping concentration described in this application includes a variety of gradient methods, where the gradient emphasizes the trend of change. For example, a gradient decrease or increase in doping concentration along the thickness direction also falls within the gradient method described in this application.

[0035] Electrons and holes recombine in the host material to form excitons, which are quasiparticles with a certain amount of energy; the sensitizer is used to transfer this part of the energy to the dye to make the dye emit light. Specifically, an exciton refers to a bound state (quasiparticle) formed by electrons and holes through Coulomb interaction. In this embodiment, in the region with a high exciton concentration, the doping concentration of the sensitizer is relatively high, and a large number of sensitizers make full use of the exciton energy and transfer this part of the exciton energy to the dye, improving the luminous efficiency of the organic electroluminescent device; and in the region with a relatively high doping concentration of the sensitizer, the doping concentration of the dye is relatively low, reducing the Dexter energy transfer probability, reducing the concentration of high-energy triplet excitons, and reducing the probability of deterioration of the luminescent layer material caused by the high-energy excitons generated by TTA, thus improving the lifespan of the organic electroluminescent device. In the luminescent layer, in the region with a low exciton concentration, the doping concentration of the sensitizer is relatively low, and the doping concentration of the dye is relatively high, and a large number of dyes can ensure the luminous efficiency of this region of the luminescent layer.

[0036] For an organic electroluminescent device in which the exciton concentration decreases in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases in the direction from the anode layer to the cathode layer, and the doping concentration of the dye increases. Specifically, for an organic electroluminescent device with a low hole mobility and a high electron mobility in the luminescent layer, carriers accumulate and recombine to form excitons on the side of the luminescent layer close to the anode layer, and the exciton concentration on the side close to the anode layer is greater than the exciton concentration on the side close to the cathode layer, that is, the exciton concentration gradually decreases in the direction from the anode layer to the cathode layer. The sensitizer is used to transfer the exciton energy to the dye to make the dye emit light. Therefore, in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases, that is, a higher concentration of the sensitizer is set in the region with a high exciton concentration to make full use of the exciton energy to transfer the energy to the dye, avoiding waste of exciton energy and improving the luminous efficiency. In the direction from the anode layer to the cathode layer, the doping concentration of the dye increases, that is, a lower concentration of the dye is set in the region with a high exciton concentration, reducing the Dexter energy transfer probability, reducing the concentration of high-energy triplet excitons, and reducing the probability of deterioration of the luminescent layer material caused by the high-energy excitons generated by TTA, thus improving the lifespan of the organic electroluminescent device; a higher concentration of the dye is set in the region with a low exciton concentration, and a large number of dyes can ensure the luminous efficiency of this region of the luminescent layer.

[0037] For an organic electroluminescent device in which the exciton concentration shows an increasing trend in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer increases in the direction from the anode layer to the cathode layer, and the doping concentration of the dye decreases. Specifically, for an organic electroluminescent device in which the electron mobility in the light-emitting layer is low while the hole mobility is high, carriers are recombined to form excitons on the side of the light-emitting layer close to the cathode layer, and the exciton concentration on the side close to the cathode layer is greater than the exciton concentration on the side close to the anode layer, that is, the exciton concentration increases in the direction from the anode layer to the cathode layer. The sensitizer is used to transfer the exciton energy to the dye to make the dye emit light. Therefore, in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer increases, that is, a higher concentration of the sensitizer is set in the region with a high exciton concentration to make full use of the exciton energy to transfer the energy to the dye, avoid waste of exciton energy, and improve the luminous efficiency. In the direction from the anode layer to the cathode layer, the doping concentration of the dye decreases, that is, a lower concentration of the dye is set in the region with a high exciton concentration to reduce the Dexter energy transfer probability, reduce the concentration of high-energy triplet excitons, reduce the probability of deterioration of the light-emitting layer material caused by the high-energy excitons generated by TTA, and improve the life of the organic electroluminescent device; a higher concentration of the dye is set in the region with a low exciton concentration, and a large amount of the dye can ensure the luminous efficiency of this region of the light-emitting layer.

[0038] Optionally, the doping concentration gradient of the sensitizer decreases, and / or the doping concentration gradient of the dye increases.

[0039] It can be understood that the doping concentration of the sensitizer is proportional to the concentration of excitons in the light-emitting layer, and the doping concentration of the dye is inversely proportional to the concentration of excitons in the light-emitting layer.

[0040] Optionally, the doping concentration range of the sensitizer is 0.5% to 15%, such as the doping concentration of the sensitizer is 0.5%, 1%, 5%, 10%, 15%, etc.; and / or the doping concentration range of the dye is 0.3% to 3%, such as the doping concentration of the dye is 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc.

[0041] It should be noted that the doping concentration of the sensitizer refers to the volume ratio of the sensitizer to the host material; the doping concentration of the dye refers to the volume ratio of the dye to the host material. Optionally, the sensitizer includes a phosphorescent sensitizer, such as tris(2-phenylpyridine)iridium (Ir(ppy)3), tris(1-phenylisoquinoline)iridium (Ir(piq)3), and the dye includes a fluorescent luminescent material, such as fluorescein (green), rhodamine B (red), coumarin (blue), DCM (red light dye).

[0042] Optionally, the host material includes a thermally activated delayed fluorescence (TADF) material, such as a carbazole- or triphenylamine-based polymer.

[0043] Specifically, in the phosphor-assisted TADF-sensitized fluorescence (pTSF) technology, the phosphor sensitizer transfers the exciton energy to the fluorescent material to make the fluorescent material emit light. In this application, by setting the TADF host and the phosphor sensitizer, the excitons in the organic electroluminescent device are fully utilized, and the utilization rate can reach 100%. Moreover, in the organic electroluminescent device of this application, phosphor-sensitized fluorescence can be realized, enabling the organic electroluminescent device to emit fluorescence. Due to the narrow spectral characteristics of fluorescence, the organic electroluminescent device finally realizes an improvement in efficiency while broadening the color gamut range.

[0044] Optionally, the thickness range of the light-emitting layer is 15 nm to 60 nm, such as 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc., to avoid increasing the overall power consumption and reducing the lifespan at the same time.

[0045] Figure 1 It is a schematic structural diagram of the organic electroluminescent device provided by the first embodiment of this application. As Figure 1 shown, in some embodiments, the organic electroluminescent device 100 includes: an anode layer 110, a hole transport region 140, a light-emitting layer 120, an electron transport region 150, and a cathode layer 130 that are sequentially stacked. The hole transport region 140 is located between the anode layer 110 and the light-emitting layer 120, and the electron transport region 150 is located between the cathode layer 130 and the light-emitting layer 120.

[0046] Optionally, the hole transport region 140 includes a hole transport layer 142 (HTL), or the hole transport region 140 includes a hole injection layer 141 (HIL) and a hole transport layer 142 that are sequentially stacked along the direction away from the anode layer 110; or the hole transport region 140 includes a hole injection layer 141, a hole transport layer 142, and an electron blocking layer 143 (EBL) that are sequentially stacked along the direction away from the anode layer 110.

[0047] Optionally, the electron transport region 150 includes an electron transport layer 152 (Electronic Transmission Layer, ETL), or the electron transport region 150 includes an electron injection layer 151 (Electron Injection Layer, EIL) and an electron transport layer 152 stacked in sequence in a direction away from the cathode layer 130; or the electron transport region 150 includes an electron injection layer 151, an electron transport layer 152, and a hole blocking layer 153 (Hole Blocking Layer, HBL) stacked in sequence in a direction away from the cathode layer 130.

[0048] The hole injection layer 141 is used to reduce the potential barrier between the anode layer 110 and the hole transport layer 142, and promote the efficient injection of holes from the anode layer 110. The hole transport layer 142 transports holes to the first light-emitting layer 120 and the second light-emitting layer 120. The electron injection layer 151 is used to reduce the potential barrier between the cathode layer 130 and the electron transport layer 152, and promote the efficient injection of electrons from the cathode layer 130. The electron transport layer 152 transports electrons to the first light-emitting layer 120 and the second light-emitting layer 120. The electron blocking layer 143 is used to block the diffusion of electrons to the hole transport layer 142, and the hole blocking layer 153 is used to block the diffusion of holes to the electron transport layer 152.

[0049] In some embodiments, in the direction from the anode layer 110 to the cathode layer 130, the doping concentration of the sensitizer 122 decreases linearly in a gradient manner, and the doping concentration of the dye 123 increases linearly in a gradient manner.

[0050] Specifically, in the light-emitting layer 120, the doping concentration of the sensitizer 122 is the highest in the partial region in contact with the electron blocking layer 143. The doping concentration range of the sensitizer 122 in this region is 5% - 15%, so as to fully absorb the exciton energy, prevent the host from emitting light by itself or directly transfer the exciton energy to the dye, and reduce the light-emitting efficiency; the doping concentration of the sensitizer 122 is the lowest in the partial region in contact with the hole blocking layer 153. The doping concentration range of the sensitizer 122 in this region is 0.5% - 5%, and 0.5% - 5% is also the minimum range of the doping concentration of the sensitizer 122, so as to make full use of the exciton energy and improve the light-emitting efficiency. The doping concentration of the dye 123 is the lowest in the partial region in contact with the electron blocking layer 143. The doping concentration range of the dye 123 in this region is 0.3% - 1.5%, and 0.3% - 1.5% is also the minimum range of the doping concentration of the dye 123, so as to balance the light-emitting lifetime and the light-emitting efficiency; the doping concentration of the dye 123 is the highest in the partial region in contact with the hole blocking layer 153. The doping concentration range of the dye 123 in this region is 1.5% - 3.0%, so as to make full use of the exciton energy and ensure the light-emitting efficiency.

[0051] In some embodiments, in the direction from the anode layer 110 to the cathode layer 130, the doping concentration of the sensitizer 122 decreases in a linear gradient, and the doping concentration of the dye 123 increases in a non-linear gradient.

[0052] In some embodiments, in the direction from the anode layer 110 to the cathode layer 130, the doping concentration of the sensitizer 122 decreases in a non-linear gradient, and the doping concentration of the dye 123 increases in a linear gradient.

[0053] In some embodiments, in the direction from the anode layer 110 to the cathode layer 130, the doping concentration of the sensitizer 122 decreases in a non-linear gradient, and the doping concentration of the dye 123 increases in a non-linear gradient.

[0054] The foregoing technical solutions will be further described below through more specific embodiments.

[0055] Embodiment 1

[0056] Figure 2 It is a partial structural schematic diagram of an organic electroluminescent device provided by the first embodiment of the present application.

[0057] As Figure 2 shown, in the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a linear gradient, and the doping concentration of the dye increases in a linear gradient. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that of other regions, and the doping concentration of the dye in region A is lower than that of other regions; the doping concentration of the sensitizer in region B is lower than that of other regions, and the doping concentration of the dye in region B is higher than that of other regions.

[0058] Embodiment 2

[0059] Figure 3 It is a partial structural schematic diagram of an organic electroluminescent device provided by the second embodiment of the present application.

[0060] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a linear gradient, and the doping concentration of the dye increases in a non-linear gradient. Specifically, as Figure 3 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the dye increases in a curve. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that of other regions, and the doping concentration of the dye in region A is lower than that of other regions; the doping concentration of the sensitizer in region B is lower than that of other regions, and the doping concentration of the dye in region B is higher than that of other regions.

[0061] Example 3

[0062] Figure 4 It is a partial structural schematic diagram of the organic electroluminescent device provided by the third embodiment of the present application.

[0063] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a linear gradient, and the doping concentration of the dye increases in a non-linear gradient. Specifically, as Figure 4 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the dye increases step by step. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0064] Example 4

[0065] Figure 5 It is a partial structural schematic diagram of the organic electroluminescent device provided by the fourth embodiment of the present application.

[0066] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a non-linear gradient, and the doping concentration of the dye increases in a linear gradient. Specifically, as Figure 5 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a curve. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0067] Example 5

[0068] Figure 6 It is a partial structural schematic diagram of the organic electroluminescent device provided by the fifth embodiment of the present application.

[0069] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a non-linear gradient, and the doping concentration of the dye increases in a linear gradient. Specifically, as Figure 6As shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases stepwise. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0070] Example 6

[0071] Figure 7 It is a partial structural schematic diagram of the organic electroluminescent device provided by the sixth embodiment of the present application.

[0072] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases non-linearly in a gradient manner, and the doping concentration of the dye increases non-linearly in a gradient manner. Specifically, as Figure 7 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a curve, and the doping concentration of the dye increases in a curve. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0073] Example 7

[0074] Figure 8 It is a partial structural schematic diagram of the organic electroluminescent device provided by the seventh embodiment of the present application.

[0075] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases non-linearly in a gradient manner, and the doping concentration of the dye increases non-linearly in a gradient manner. Specifically, as Figure 8 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a curve, and the doping concentration of the dye increases stepwise. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0076] Example 8

[0077] Figure 9It is a partial structural schematic diagram of the organic electroluminescent device provided by the eighth embodiment of the present application.

[0078] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a non-linear gradient, and the doping concentration of the dye increases in a non-linear gradient. Specifically, as Figure 9 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases step by step, and the doping concentration of the dye increases in a curve. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0079] Example 9

[0080] Figure 10 It is a partial structural schematic diagram of the organic electroluminescent device provided by the ninth embodiment of the present application.

[0081] In the direction from the anode layer to the cathode layer, that is, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases in a non-linear gradient, and the doping concentration of the dye increases in a non-linear gradient. Specifically, as Figure 10 shown, in the direction from the electron blocking layer 143 to the hole blocking layer 153, the doping concentration of the sensitizer decreases step by step, and the doping concentration of the dye increases step by step. Among them, the doping concentration of the sensitizer in region A of the light-emitting layer 120 is higher than that in other regions, and the doping concentration of the dye in region A is lower than that in other regions; the doping concentration of the sensitizer in region B is lower than that in other regions, and the doping concentration of the dye in region B is higher than that in other regions.

[0082] Comparative Example 1

[0083] In the direction from the anode layer to the cathode layer, both the sensitizer and the dye are doped into the host material at a fixed doping concentration, that is, in the direction from the anode layer to the cathode layer, the doping concentrations of both the sensitizer and the dye remain unchanged.

[0084] Comparative Example 2

[0085] In the direction from the anode layer to the cathode layer, the sensitizer is doped into the host material at a fixed doping concentration, and the doping concentration of the dye increases in a linear gradient, that is, in the direction from the electron blocking layer to the hole blocking layer, the doping concentration of the sensitizer remains unchanged, and the doping concentration of the dye increases in a linear gradient.

[0086] Comparative Example 3

[0087] In the direction from the anode layer to the cathode layer, the dye is doped in the host material at a fixed doping concentration, and the doping concentration of the sensitizer increases linearly in a gradient manner, that is, in the direction from the electron blocking layer to the hole blocking layer, the doping concentration of the sensitizer increases linearly in a gradient manner, and the doping concentration of the dye remains unchanged.

[0088] It should be noted that between Examples 1 - 9 and Comparative Examples 1 - 3, except for the different doping concentration methods of the sensitizer and the dye in the light-emitting layer 120, other structures and process parameters are the same.

[0089] The performance of the organic electroluminescent devices 100 of Examples 1 - 9 was compared with that of the organic electroluminescent devices 100 of Comparative Examples 1 - 3, and the results are shown in Table 1. Among them, the lifetime test was carried out using the equipment of Fstar, and the test condition was 15 mA / cm 2 ; the efficiency test was carried out through the IVL test equipment of Jinghe, and the test condition was 10 mA / cm 2 .

[0090] Table 1

[0091]

[0092]

[0093] According to the test results in Table 1, it can be seen that the lifetime of the organic electroluminescent devices provided in Examples 1 - 9 is higher than that of the organic electroluminescent devices provided in the comparative examples, and the efficiency of the organic electroluminescent devices provided in Examples 1 - 9 is greater than that of the organic electroluminescent devices provided in Comparative Examples 1 - 3. It shows that the technical solution of the present application can effectively improve the lifetime and luminous efficiency of the organic electroluminescent devices.

[0094] Figure 11 It is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of the present application. As Figure 11 shown, the present application provides an organic electroluminescent device 100, which includes an anode layer 110, at least two stacked light-emitting layers 120 stacked in sequence, and a cathode layer 130, and at least one light-emitting layer is the light-emitting layer mentioned above.

[0095] Taking the example of an organic electroluminescent device 100 including two light-emitting layers 120, in some embodiments, the structure of one of the light-emitting layers 120 is the same as that of the light-emitting layer mentioned above. That is, in the direction from the anode layer to the cathode layer, the sensitizer of one of the light-emitting layers 120 is doped into the host material in a manner of gradient doping concentration, and the dye is doped into the host material in a manner of gradient doping concentration, and the changing direction of the gradient doping concentration of the sensitizer is opposite to the changing direction of the gradient doping concentration of the dye; the sensitizer and the dye of the other light-emitting layer 120 are both doped in a manner of fixed doping concentration. In some embodiments, the structures of the two light-emitting layers 120 are both the same as that of the light-emitting layer mentioned above. That is, in the direction from the anode layer to the cathode layer, the sensitizers of the two light-emitting layers 120 are both doped into the host material in a manner of gradient doping concentration, and the dyes are both doped into the host material in a manner of gradient doping concentration, and the changing direction of the gradient doping concentration of the sensitizer is opposite to the changing direction of the gradient doping concentration of the dye. The specific doping methods of the sensitizer and the dye in the light-emitting layer 120 are as mentioned in the above embodiments, and will not be elaborated here.

[0096] In some embodiments, a charge generation layer is disposed between two adjacent light-emitting layers 120.

[0097] It should be noted that the present application does not limit the number of the light-emitting layers 120, and multiple light-emitting layers are connected in series.

[0098] The present application provides a display panel, including: a substrate and the organic electroluminescent device mentioned above, and the organic electroluminescent device is located on the substrate.

[0099] Among them, the substrate may include a substrate and a circuit layer formed on the substrate, etc. The substrate may be a rigid substrate or a flexible substrate. The circuit layer may include multiple wiring layers and dielectric layers for isolating the wiring layers, etc., and pixel circuits, etc. may be formed in the circuit layer.

[0100] Figure 12 It is a schematic structural diagram of a display panel provided by an embodiment of the present application.

[0101] As Figure 12 shown, in some embodiments, the organic electroluminescent device 100 includes an anode layer 110, a light-emitting layer 120, and a cathode layer 130 that are sequentially stacked along the direction away from the substrate. The display panel 200 further includes: a substrate 210, the organic electroluminescent device 100 mentioned above, and a light extraction layer 220. The organic electroluminescent device includes an anode layer 110, a light-emitting layer 120, and a cathode layer 130 that are sequentially stacked along the direction away from the substrate 210. The light extraction layer 220 is located on the side of the cathode layer 130 away from the substrate 210.

[0102] Optionally, the refractive index of the material of the light extraction layer 220 ranges from 1.7 to 2.2, such as 1.7, 1.9, 2.1, 2.2, etc., to balance the extinction rate and improve the light extraction efficiency.

[0103] Optionally, the thickness of the light extraction layer 220 ranges from 50 nm to 80 nm, such as 50 nm, 60 nm, 70 nm, 80 nm, etc., to evenly improve the light emission efficiency.

[0104] Figure 13 It is a schematic flow chart of a method for manufacturing a display panel provided by an embodiment of the present application. As Figure 13 shown, the present application provides a method for manufacturing a display panel, including:

[0105] Step S101: Prepare an anode layer on a substrate.

[0106] Step S102: Prepare a light-emitting layer on the side of the anode layer facing away from the substrate.

[0107] Among them, the light-emitting layer includes a host material, a sensitizer, and a dye; the sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the light-emitting layer, the doping concentration of the sensitizer decreases, and the doping concentration of the dye increases.

[0108] Step S103: Prepare a cathode layer on the side of the light-emitting layer facing away from the substrate.

[0109] Specifically, the cathode layer may include a magnesium (Mg)-silver (Ag) alloy, or a transparent metal oxide such as indium zinc oxide (IZO). In this embodiment, the Mg-Ag alloy is used as the cathode, and the thickness is 10 nm to 15 nm.

[0110] In some embodiments, preparing a light-emitting layer on the side of the anode layer facing away from the substrate includes:

[0111] Placing the host material, the sensitizer, and the dye in different evaporation sources respectively, and changing the doping concentration of the sensitizer by changing the evaporation rate of the sensitizer, changing the doping concentration of the dye by changing the evaporation rate of the dye, and realizing the stable evaporation of the host material by stabilizing the evaporation rate of the host material. That is, according to the doping concentrations of the sensitizer and the dye, the evaporation rates of the sensitizer and the dye are respectively controlled.

[0112] Specifically, the evaporation rate of the sensitizer is changed by controlling the evaporation temperature of the evaporation source where the sensitizer is placed, and the evaporation rate of the dye is changed by controlling the evaporation temperature of the evaporation source where the dye is placed. It can be understood that the higher the evaporation temperature, the greater the evaporation rate.

[0113] For an organic electroluminescent device in which the concentration gradient of excitons shows a decreasing trend in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases in a gradient manner in the direction from the anode layer to the cathode layer, and the doping concentration of the dye increases in a gradient manner. Therefore, when preparing this organic electroluminescent device, as the evaporation time changes, the evaporation rate of the sensitizer decreases, and the evaporation rate of the dye increases. That is, as the evaporation time changes, the evaporation temperature of the evaporation source of the sensitizer decreases, and the evaporation temperature of the evaporation source of the dye increases. Specifically, the evaporation temperature of the evaporation source of the sensitizer and the evaporation temperature of the evaporation source of the dye change according to the changes in the doping concentrations of the sensitizer and the dye.

[0114] For an organic electroluminescent device in which the concentration gradient of excitons shows an increasing trend in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer increases in a gradient manner in the direction from the anode layer to the cathode layer, and the doping concentration of the dye decreases in a gradient manner. Therefore, when preparing this organic electroluminescent device, as the evaporation time changes, the evaporation rate of the sensitizer increases, and the evaporation rate of the dye decreases. That is, as the evaporation time changes, the evaporation temperature of the evaporation source of the sensitizer increases, and the evaporation temperature of the evaporation source of the dye decreases. Specifically, the evaporation temperature of the evaporation source of the sensitizer and the evaporation temperature of the evaporation source of the dye change according to the changes in the doping concentrations of the sensitizer and the dye.

[0115] In some embodiments, before the step of preparing the light-emitting layer on the side of the anode layer facing away from the substrate, the preparation method further includes: sequentially preparing a hole injection layer, a hole transport layer, and an electron blocking layer on the side of the anode layer facing away from the substrate.

[0116] Among them, the hole injection layer is composed of a hole transport material and a hole injection material, and the hole injection material accounts for 0.5-5% of the content of this layer, such as 0.5%, 1%, 2%, 3%, 4%, 5%, etc., and the thickness of this layer is 3 nm-15 nm, such as 3 nm, 5 nm, 10 nm, 15 nm, etc. The hole transport layer is composed of the same hole transport material as the hole injection layer, and the thickness is 80 nm-150 nm, such as 80 nm, 100 nm, 120 nm, 140 nm, 150 nm, etc. The electron blocking layer is composed of a hole transport material with a relatively shallow lowest unoccupied molecular orbital (LUMO) that is not occupied by electrons, and the thickness is 3 nm-150 nm, such as 3 nm, 10 nm, 50 nm, 100 nm, 120 nm, 150 nm, etc. Since the thicknesses of the red organic electroluminescent device, the green organic electroluminescent device, and the blue organic electroluminescent device are different, the materials of the corresponding electron blocking layers for the three can be the same or different. Specifically, Figure 14 It is a distribution diagram of the exciton recombination region in the light-emitting layer of the red organic electroluminescent device, the green organic electroluminescent device, and the blue organic electroluminescent device, such as Figure 14As shown, within the light-emitting layers of the red organic electroluminescent device, the green organic electroluminescent device, and the blue organic electroluminescent device, a large number of excitons recombine near the interface between the electron blocking layer and the light-emitting layer, that is, the exciton energy within the device is fully utilized to improve the light-emitting efficiency.

[0117] Optionally, after the step of preparing the light-emitting layer on the side of the anode layer away from the substrate, the preparation method further includes: sequentially preparing a hole blocking layer, an electron transport layer, and an electron injection layer on the side of the light-emitting layer away from the substrate.

[0118] Among them, the material of the hole blocking layer is a material with a relatively deep highest occupied molecular orbital (HOMO), and the thickness of this layer is 3 nm to 8 nm, such as 3 nm, 5 nm, 7 nm, 8 nm, etc. The electron transport layer is composed of an electron transport material and lithium 8-hydroxyquinolate (LiQ), and the doping ratio of LiQ in the electron transport material is between 30% and 70%, such as 30%, 40%, 50%, 60%, 70%, etc., and the thickness of this layer is 25 nm to 35 nm, such as 25 nm, 30 nm, 35 nm, etc. The electron injection layer is lithium 8-hydroxyquinolate (LiQ) or lithium fluoride (LiF) or ytterbium (Yb) or magnesium (Mg) doped lithium fluoride (LiF). In this embodiment, the electron injection layer includes ytterbium (Yb) and has a thickness of 0.5 nm to 1.5 nm.

[0119] Optionally, the hole injection layer, the hole transport layer, and the electron blocking layer are prepared by a vapor deposition process; and / or, the hole blocking layer, the electron transport layer, and the electron injection layer are prepared by a vapor deposition process. Optionally, the hole injection layer, the hole transport layer, and the electron blocking layer are prepared by a vapor deposition process; and / or, the hole blocking layer, the electron transport layer, and the electron injection layer are prepared by a vacuum vapor deposition process.

[0120] Optionally, the preparation method further includes: preparing a light extraction layer on the side of the cathode layer away from the substrate. The light extraction layer includes a high refractive index material with a refractive index of 1.7 to 2.2, such as 1.7, 1.9, 2.1, 2.2, etc., and the thickness of this layer is 50 nm to 80 nm, such as 50 nm, 60 nm, 70 nm, 80 nm, etc.

[0121] Optionally, after the step of preparing the light extraction layer, the preparation method further includes: performing a packaging process.

[0122] Figure 15 It is a schematic structural diagram of a display device provided by an embodiment of the present application. As Figure 15 shown, the present application provides a display device 1100, which includes the display panel 200 mentioned above or includes the display panel 200 prepared according to the preparation method mentioned above.

[0123] The display device 1100 is a product with an image display function. For example, the display device 1100 can be used to display static images, such as pictures or photos. The display device 1100 can also be used to display dynamic images, such as videos.

[0124] The display device 1100 can be a laptop, mobile phone, handheld or portable computer, camera, video camera, in-vehicle intelligent central control screen, calculator, smart watch, GPS navigator, digital photo frame, electronic billboard or sign, projector, etc.

[0125] The display device 1100 includes the display panel provided in any of the above embodiments. The display panel can be an organic light-emitting diode display panel or a quantum dot electroluminescent display panel.

[0126] In addition, the display device 1100 can also have functions such as taking pictures, recording videos, fingerprint recognition, and face recognition. Accordingly, the display device 1100 also includes at least one functional module for implementing the above functions, such as an under-screen camera, an under-screen fingerprint recognition sensor, etc.

[0127] The basic principles of the present application have been described in conjunction with specific embodiments. However, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, benefits, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for illustrative purposes and for ease of understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details for implementation.

[0128] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any way. Words such as "including", "comprising", "having", etc. are open-ended terms, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein refer to the word "and / or" and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to" and can be used interchangeably with each other.

[0129] It should also be noted that in the devices, equipment, and methods of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of the present application.

[0130] The foregoing description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Thus, the present application is not intended to be limited to the aspects shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0131] The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the form disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize some variations, modifications, alterations, additions, and subcombinations thereof.

[0132] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, subcombinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An organic electroluminescent device, characterized in that, Comprising: An anode layer, a light-emitting layer, and a cathode layer that are stacked in sequence; wherein, The light-emitting layer includes a host material, a sensitizer, and a dye; the sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the cathode layer, the doping concentration of the sensitizer decreases, and the doping concentration of the dye increases.

2. The organic electroluminescent device according to claim 1, wherein The doping concentration gradient of the sensitizer decreases, and / or the doping concentration gradient of the dye increases; Preferably, the sensitizer includes a phosphorescent sensitizer, and the dye includes a fluorescent luminescent material; Preferably, the host material includes a thermally activated delayed fluorescence material; Preferably, the thickness range of the light-emitting layer is 15 nm to 60 nm.

3. The organic electroluminescent device according to claim 1 or 2, characterized in that, In the direction from the anode layer to the cathode layer, the doping concentration range of the sensitizer is 0.5% to 15%; and / or the doping concentration range of the dye is 0.3% to 3%; Preferably, the doping concentration range of the sensitizer is 5% to 15%, Preferably, the doping concentration range of the sensitizer is 0.5% to 5%; and / or, Preferably, the doping concentration range of the dye is 1.5% to 3.0%, Preferably, the doping concentration range of the dye is 0.3% to 1.5%.

4. The organic electroluminescent device according to claim 1, characterized in that, Further comprising: A hole transport region and an electron transport region, the hole transport region is located between the anode layer and the light-emitting layer, and the electron transport region is located between the cathode layer and the light-emitting layer; Preferably, the hole transport region includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer; Preferably, the electron transport region includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer.

5. An organic electroluminescent device, characterized in that, Comprising an anode layer, at least two stacked light-emitting layers, and a cathode layer that are stacked in sequence, and at least one of the light-emitting layers is the light-emitting layer according to any one of claims 1 to 4.

6. A display panel, characterized in that, Comprising: A substrate; The organic electroluminescent device according to any one of claims 1 to 5, and the organic electroluminescent device is located on the substrate.

7. The display panel according to claim 6, wherein, The organic electroluminescent device includes an anode layer, a light-emitting layer, and a cathode layer that are stacked in sequence along the direction away from the substrate, and the display panel further includes: a light extraction layer, and the light extraction layer is located on the side of the cathode layer away from the substrate; Preferably, the refractive index range of the material of the light extraction layer is 1.7 to 2.2; Preferably, the thickness range of the light extraction layer is 50 to 80 nm.

8. A method for preparing a display panel, characterized in that, Comprising: Preparing an anode layer on a substrate; Preparing a light-emitting layer on the side of the anode layer away from the substrate, and the light-emitting layer includes a host material, a sensitizer, and a dye; The sensitizer and the dye are doped in the host material, and in the direction from the anode layer to the light-emitting layer, the doping concentration of the sensitizer decreases, and the doping concentration of the dye increases; Preparing a cathode layer on the side of the light-emitting layer away from the substrate.

9. The method for manufacturing a display panel according to claim 8, wherein, The step of preparing the light-emitting layer on the side of the anode layer away from the substrate includes: Place the host material, the sensitizer, and the dye in different evaporation sources respectively. By changing the evaporation rate of the sensitizer, the doping concentration of the sensitizer is changed. By changing the evaporation rate of the dye, the doping concentration of the dye is changed. By stabilizing the evaporation rate of the host material, the stable evaporation of the host material is achieved. Preferably, the evaporation rate of the sensitizer is changed by controlling the evaporation temperature of the evaporation source where the sensitizer is placed, and the evaporation rate of the dye is changed by controlling the evaporation temperature of the evaporation source where the dye is placed. Preferably, as the evaporation time changes, the evaporation rate of the sensitizer decreases, and the evaporation rate of the dye increases. Preferably, before the step of preparing the light-emitting layer on the side of the anode layer facing away from the substrate, the preparation method further includes: sequentially preparing a hole injection layer, a hole transport layer, and an electron blocking layer on the side of the anode layer facing away from the substrate. Preferably, after the step of preparing the light-emitting layer on the side of the anode layer facing away from the substrate, the preparation method further includes: sequentially preparing a hole blocking layer, an electron transport layer, and an electron injection layer on the side of the light-emitting layer facing away from the substrate. Preferably, the hole injection layer, the hole transport layer, and the electron blocking layer are prepared by an evaporation process; and / or, the hole blocking layer, the electron transport layer, and the electron injection layer are prepared by an evaporation process. Preferably, the preparation method further includes: preparing a light extraction layer on the side of the cathode layer facing away from the substrate.

10. A display device, characterized in that, A display panel including the display panel according to claim 6 or 7, or a display panel prepared by the preparation method according to claim 8 or 9.

Images