Light-emitting device and display panel

Abstract

The application provides a light-emitting device and a display panel. An organic electroluminescent device comprises an anode layer, a first light-emitting layer, a second light-emitting layer and a cathode layer which are sequentially stacked; wherein the first light-emitting layer comprises a first sensitizer, the second light-emitting layer comprises a second sensitizer, the first sensitizer comprises a thermally activated delayed material, and the second sensitizer comprises a phosphorescent material. The technical solution in the application can improve the service life and light-emitting efficiency of the organic electroluminescent device.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a light-emitting device and a display panel. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are devices that emit light through electric current. Specifically, an OLED comprises a cathode layer, an anode layer, and a light-emitting layer located between the cathode and anode layers. When a voltage is applied, electrons from the cathode layer and holes from the anode layer migrate to the light-emitting layer and recombine to generate excitons, which then emit light of different wavelengths depending on the characteristics of the light-emitting layer. However, some problems still exist with organic light-emitting diodes. Summary of the Invention

[0003] To address the aforementioned issues, this application provides a light-emitting device and a display panel.

[0004] In a first aspect, embodiments of this application provide a light-emitting device, comprising: an anode layer, a first light-emitting layer, a second light-emitting layer, and a cathode layer sequentially stacked; wherein the first light-emitting layer comprises a first sensitizer, the second light-emitting layer comprises a second sensitizer, the first sensitizer comprises a thermally activated delayed material, and the second sensitizer comprises a phosphorescent material.

[0005] In conjunction with the first aspect, the first light-emitting layer further includes a first host material, and the second light-emitting layer further includes a second host material; preferably, the LUMO energy level of the first sensitizer is deeper than the LUMO energy level of the first host material, and / or, the HOMO energy level of the second sensitizer is shallower than the HOMO energy level of the second host material; preferably, the triplet energy level of the first host material is greater than or equal to the triplet energy level of the first sensitizer; and / or, the triplet energy level of the second host material is greater than or equal to the triplet energy level of the second sensitizer; preferably, the difference between the triplet energy level of the first host material and the triplet energy level of the first sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV; and / or, the difference between the triplet energy level of the second host material and the triplet energy level of the second sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV.

[0006] In conjunction with the first aspect, at least one of the first and second light-emitting layers comprises a dye; preferably, the first light-emitting layer comprises a first dye; and / or, the second light-emitting layer comprises a second dye, wherein the materials of the first dye and the second dye are the same; preferably, the singlet energy level of the first host material is greater than or equal to the singlet energy level of the first dye; and / or, the singlet energy level of the second host material is greater than or equal to the singlet energy level of the second dye; preferably, the difference between the singlet energy level of the first host material and the singlet energy level of the first dye is greater than or equal to 0 eV and less than or equal to 0.5 eV; and / or, the second The difference between the singlet energy level of the host material and the singlet energy level of the second dye is greater than or equal to 0 eV and less than or equal to 0.5 eV; preferably, the first host material comprises a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone, and sulfone; and / or, the second host material is a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone, and sulfone; preferably, the first host material and the second host material are the same; preferably, the dye comprises a fluorescent dye.

[0007] In conjunction with the first aspect, the first light-emitting layer further includes a first host material and a first dye, and the second light-emitting layer further includes a second host material and a second dye; preferably, the materials of the first dye and the second dye are the same; preferably, in the first light-emitting layer, the mass content of the first sensitizer ranges from 1% to 70%; the mass content of the first dye ranges from 0.1% to 10%; and / or, in the second light-emitting layer, the mass content of the second sensitizer ranges from 1% to 70%; the mass content of the second dye ranges from 0.1% to 10%.

[0008] In conjunction with the first aspect, the first light-emitting layer further includes a first host material and a first dye, and the second light-emitting layer further includes a second host material; preferably, in the first light-emitting layer, the mass content of the first sensitizer ranges from 1% to 70%; the mass content of the first dye ranges from 0.1% to 10%; and / or, in the second light-emitting layer, the mass content of the second sensitizer ranges from 1% to 70%.

[0009] In conjunction with the first aspect, the first light-emitting layer further includes a first host material, and the second light-emitting layer further includes a second host material and a second dye; preferably, in the first light-emitting layer, the mass content of the first sensitizer ranges from 1% to 70%; and / or, in the second light-emitting layer, the mass content of the second sensitizer ranges from 1% to 70%, and the mass content of the second dye ranges from 0.1% to 10%.

[0010] In conjunction with the first aspect, the thickness of the first light-emitting layer ranges from 5 nm to 80 nm; and / or, the thickness of the second light-emitting layer ranges from 5 nm to 80 nm.

[0011] In conjunction with the first aspect, the light-emitting device further includes an intermediate layer located between the first light-emitting layer and the second light-emitting layer; preferably, the first light-emitting layer further includes a first host material, the second light-emitting layer further includes a second host material, and the material of the intermediate layer is the same as the first host material or the second host material; preferably, the thickness of the intermediate layer is in the range of 5nm-80nm.

[0012] In conjunction with the first aspect, it also includes a hole transport region and an electron transport region, wherein the hole transport region is located between the anode layer and the first light-emitting layer, and the electron transport region is located between the cathode layer and the second light-emitting layer; preferably, the hole transport region includes a hole transport layer, or the hole transport region includes a hole injection layer and a hole transport layer stacked sequentially in the direction away from the anode layer; or the hole transport region includes a hole injection layer, a hole transport layer and an electron blocking layer stacked sequentially in the direction away from the anode layer; preferably, the electron transport region includes an electron transport layer, or the electron transport region includes an electron injection layer and an electron transport layer stacked sequentially in the direction away from the cathode layer; or the electron transport region includes an electron injection layer, an electron transport layer and a hole blocking layer stacked sequentially in the direction away from the cathode layer.

[0013] This application also provides a display panel including any of the light-emitting devices mentioned above.

[0014] The light-emitting device and display panel provided in this application have an anode layer, a first light-emitting layer, a second light-emitting layer, and a cathode layer stacked sequentially. The first light-emitting layer includes a first sensitizer, and the second light-emitting layer includes a second sensitizer. The first and second sensitizers are made of different materials. Specifically, the first sensitizer includes a thermally activated delayed material, and the second sensitizer includes a phosphorescent material. This design brings the carrier recombination region of the light-emitting device closer to the center of the entire device, avoiding shrinkage of the photon release area. In this application, the photon release area is relatively large, reducing the energy density per unit area and thus reducing the probability of photon quenching, thereby improving the lifespan and luminous efficiency of the light-emitting device. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application.

[0016] Figure 2 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application.

[0017] Figure 3 This is an energy level diagram of a light-emitting device provided in an embodiment of this application.

[0018] Figure 4 This is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this application.

[0019] Figure 5 This is an energy level diagram of a light-emitting device provided in another embodiment of this application.

[0020] Figure 6 This is a schematic diagram of the structure of a light-emitting device provided in another embodiment of this application.

[0021] Figure 7 This is an energy level diagram of a light-emitting device provided in another embodiment of this application.

[0022] Figure 8 This is a schematic diagram of the specific structure of a light-emitting device provided in another embodiment of this application.

[0023] Figure 9 This is a schematic diagram of the specific structure of a light-emitting device provided in another embodiment of this application.

[0024] Figure 10 This is a schematic diagram of the specific structure of a light-emitting device provided in another embodiment of this application.

[0025] Figure 11 This is a schematic diagram of the structure of a display panel provided in another embodiment of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 100 Light-emitting device; 110 Anode layer; 120 First light-emitting layer; 121 First sensitizer; 122 First host material; 123 First dye; 124 First carrier recombination region; 130 Second light-emitting layer; 131 Second sensitizer; 132 Second host material; 133 Second dye; 134 Second carrier recombination region; 140 Cathode layer; 150 Intermediate layer; 160 Hole transport region; 161 Hole injection layer; 162 Hole transport layer; 163 Electron blocking layer; 170 Electron transport region; 171 Electron injection layer; 172 Electron transport layer; 173 Hole blocking layer; 1100 Display panel; A Carrier recombination region. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application. For example... Figure 1 As shown, the light-emitting device 100 includes an anode layer 110, a first light-emitting layer 120, a second light-emitting layer 130, and a cathode layer 140 stacked sequentially.

[0030] Understandably, the light-emitting device 100 is an organic electroluminescent device.

[0031] The first light-emitting layer 120 includes a first sensitizer, and the second light-emitting layer 130 includes a second sensitizer. The materials of the first sensitizer and the second sensitizer are different.

[0032] The anode layer 110 can be made of oxide transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), and any combination thereof; the cathode layer 140 can be made of metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), and any combination thereof.

[0033] The first sensitizer includes a thermally activated delayed fluorescence material, and the second sensitizer includes a phosphorescent material. Further, the first sensitizer includes a thermally activated delayed fluorescence material. Taking the first sensitizer including a thermally activated delayed fluorescence material and the second sensitizer including a phosphorescent material as an example, the first emitting layer 120 is close to the anode layer 110, and the second emitting layer 130 is close to the cathode layer 140. After a voltage is applied, the thermally activated delayed fluorescence sensitizer (TADF Sensitizer, TS) in the first emitting layer 120 captures electrons within the device, causing the carrier recombination region of the first emitting layer 120 to be located in a portion of the first emitting layer 120 near the cathode layer 140 of the organic electroluminescent device 100; the phosphorescent sensitizer in the second emitting layer 130... The sensor (PS) captures holes within the device, causing the carrier recombination region of the second light-emitting layer 130 to be located in a portion of the second light-emitting layer 130 near the anode layer 110 of the organic electroluminescent device 100. This, in turn, brings the carrier recombination region of the organic electroluminescent device 100 closer to the center of the entire electroluminescent device, avoiding shrinking the photon release area. In this application, the photon release area is relatively large, reducing the energy density per unit area, thereby reducing the probability of photon quenching and improving the lifetime and luminous efficiency of the organic electroluminescent device 100.

[0034] In some embodiments, the first light-emitting layer 120 further includes a first host material, and the second light-emitting layer 130 further includes a second host material.

[0035] In some embodiments, at least one of the first light-emitting layer 120 and the second light-emitting layer 130 includes a dye.

[0036] Optionally, the first light-emitting layer 120 includes a first dye; and / or, the second light-emitting layer 130 includes a second dye, wherein the material of the first dye and the material of the second dye are the same.

[0037] It is worth noting that the first host material and the second host material are used to provide energy, the first sensitizer is used to transfer the energy of the first host to the first dye, and the first dye emits light, and the second sensitizer is used to transfer the energy of the second host to the second dye, and the second dye emits light.

[0038] Optionally, the triplet energy level of the first host material is greater than or equal to the triplet energy level of the first sensitizer, and / or the triplet energy level of the second host material is greater than or equal to the triplet energy level of the second sensitizer.

[0039] Optionally, the singlet energy level of the first host material is greater than or equal to the singlet energy level of the first dye; and / or, the singlet energy level of the second host material is greater than or equal to the singlet energy level of the second dye.

[0040] Specifically, methods for measuring triplet energy levels can include low-temperature phosphorescence spectroscopy, energy transfer methods, photoacoustic calorimetry, and electron paramagnetic resonance methods. Methods for measuring singlet energy levels can include fluorescence spectroscopy and excited-state absorption spectroscopy. Methods for measuring the difference between singlet and triplet energy levels include coupled fluorescence and phosphorescence spectroscopy, transient fluorescence / phosphorescence lifetime analysis, and quantum chemical calculations. It is worth noting that this application does not specifically limit the methods for measuring triplet energy levels, singlet energy levels, or the methods for measuring the difference between singlet and triplet energy levels.

[0041] Specifically, the first host material, the second host material, TS, and PS all include the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO).

[0042] In the first light-emitting layer 120, since the LUMO energy level of TS is deeper than that of the first host material, the electron transport process encounters a large energy level step (energy barrier), resulting in low electron mobility. Electrons accumulate at the interface near the cathode layer 140, forming a localized high-concentration electron region. Meanwhile, the diffusion of holes is not affected. Therefore, the recombination region of the first light-emitting layer 120 is close to the cathode layer 140. That is, the carrier recombination region of the first light-emitting layer 120 is located in a part of the first light-emitting layer 120 near the cathode layer 140 of the organic electroluminescent device 100.

[0043] In the second light-emitting layer 130, since the HOMO energy level of PS is shallower than that of the second host material, the hole transport process encounters a large energy level step (energy barrier), resulting in low hole mobility. Holes accumulate at the interface near the anode layer 110, forming a localized high-concentration hole region. Meanwhile, the diffusion of electrons is not affected. Therefore, the recombination region of the second light-emitting layer 130 is close to the anode layer 110. That is, the carrier recombination region of the second light-emitting layer 130 is located in a part of the second light-emitting layer 130 near the anode layer 110 of the organic electroluminescent device 100.

[0044] Optionally, the energy difference between the triplet energy level of the first host material and the triplet energy level of the first sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV, such as 0 eV, 0.20 eV, 0.30 eV, 0.40 eV, 0.50 eV, etc.; the energy difference between the triplet energy level of the second host material and the triplet energy level of the second sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV, such as 0 eV, 0.30 eV, 0.50 eV, etc. Within this energy level difference range, the triplet energy of the first host material can be effectively transferred to the triplet state of the first sensitizer through the Dexter energy transfer path, and the triplet energy of the second host material can be effectively transferred to the triplet state of the second sensitizer through the Dexter energy transfer path.

[0045] Optionally, the energy difference between the singlet energy level of the first host material and the singlet energy level of the first dye is greater than or equal to 0 eV and less than or equal to 0.5 eV, such as 0 eV, 0.30 eV, 0.50 eV, etc.; and / or, the energy difference between the singlet energy level of the second host material and the singlet energy level of the second dye is greater than or equal to 0 eV and less than or equal to 0.5 eV, such as 0 eV, 0.30 eV, 0.50 eV, etc. Within this energy level difference range, the singlet energy of the first host material can be... The energy transfer pathway effectively transfers energy to the singlet state of the first sensitizer, and the singlet state energy of the second host can be transferred through... The energy transfer pathway effectively transfers energy to the singlet state of the second sensitizer.

[0046] Optionally, the first host material 122 comprises a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrazine, pyridazine, benzophenone, and sulfone; and / or, the second host material 132 is a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrazine, pyridazine, benzophenone, and sulfone.

[0047] Optionally, the first main body material 122 and the second main body material 132 are the same.

[0048] Optionally, the dye is a fluorescent dye.

[0049] Optionally, the first sensitizer and the second sensitizer can form an excitosome complex.

[0050] Figure 2 This is a schematic diagram of the structure of an organic electroluminescent device provided in an embodiment of this application. Figure 3 This is an energy level diagram of an organic electroluminescent device provided in an embodiment of this application.

[0051] like Figure 2 and Figure 3 As shown, in some embodiments, the first light-emitting layer 120 includes a first host material 122, a first sensitizer 121 and a first dye 123, and the second light-emitting layer 130 includes a second host material 132, a second sensitizer 131 and a second dye 133.

[0052] Optionally, the material of the first dye 123 is the same as the material of the second dye 133.

[0053] In the first luminescent layer 120, the mass content of the first sensitizer 121 ranges from 1% to 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; the mass content of the first dye 123 ranges from 0.1% to 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; and / or, in the second luminescent layer 130, the mass content of the second sensitizer 131 ranges from 1% to 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; the mass content of the second dye 133 ranges from 0.1% to 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0054] Specifically, electrons and holes recombine in the first host material 122 or the first sensitizer 121 near the cathode layer 140 to form excitons; electrons and holes recombine in the second host material 132 or the second sensitizer 131 near the anode layer 110 to form excitons.

[0055] In the first main material 122, excitons in the singlet and triplet states respectively pass through... Energy is transferred to the first sensitizer 121 via Dexter energy transfer; excitons in the singlet and triplet states of the second host material 132 are respectively transferred through... Energy is transferred to Dexter and then to the second sensitizer 131.

[0056] In the first sensitizer 121, excitons in the singlet state reach the triplet state through intergap crossing (ISC); or excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC); in the second sensitizer 131, excitons in the singlet state reach the triplet state through intergap crossing (ISC).

[0057] The first sensitizer 121 achieves high efficiency and long-range... The energy transfer process transfers singlet exciton energy to the first dye 123 in the first luminescent layer 120 and / or the second dye 133 in the second luminescent layer 130; the second sensitizer 131 transmits energy via a highly efficient long-range... The energy transfer process transfers triplet exciton energy to the first dye 123 in the first luminescent layer 120 and / or the second dye 133 in the second luminescent layer 130.

[0058] It is worth noting that, since the first sensitizer 121 includes a thermally activated delayed fluorescence material, excitons in the singlet state of the first sensitizer 121 reach the triplet state through intergap crossing (ISC), and excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC). All excitons in the triplet state transition to the singlet state, and then from the singlet state through... The energy transfer process transfers all excitons to the first dye 123 in the first luminescent layer 120 and / or the second dye 133 in the second luminescent layer 130, thereby enabling 100% utilization of the excitons in the first sensitizer 121. Excitons in the second sensitizer 131 can transition from a singlet state to a triplet state; that is, all excitons in the singlet state transition to the triplet state, and then from the triplet state through… The energy transfer process transfers all excitons to the first dye 123 in the first light-emitting layer 120 and / or the second dye 133 in the second light-emitting layer 130, thereby enabling the excitons of the second sensitizer 131 to also achieve 100% utilization.

[0059] The first dye 123 achieves carrier recombination based on the energy transferred from the first sensitizer 121 and the second sensitizer 131, thereby emitting light; the second dye 133 achieves carrier recombination based on the energy transferred from the first sensitizer 121 and the second sensitizer 131, thereby emitting light.

[0060] Specifically, by Figure 2As shown, the carrier recombination region A is located in a portion of the first light-emitting layer 120 near the cathode layer 140 of the organic electroluminescent device 100 and a portion of the second light-emitting layer 130 near the anode layer 110 of the organic electroluminescent device 100. This makes the carrier recombination region A of the organic electroluminescent device 100 closer to the center of the entire electroluminescent device. In this application, the carrier recombination region is relatively large, which reduces the energy density per unit area, thereby reducing the probability of photon quenching and improving the lifetime and luminous efficiency of the organic electroluminescent device 100.

[0061] Figure 4 This is a schematic diagram of the structure of an organic electroluminescent device provided in another embodiment of this application. Figure 5 This is an energy level diagram of an organic electroluminescent device provided in another embodiment of this application.

[0062] like Figure 4 and Figure 5 As shown, in some embodiments, the first light-emitting layer 120 includes a first host material 122, a first sensitizer 121 and a first dye 123, and the second light-emitting layer 130 includes a second host material 132 and a second sensitizer 131.

[0063] In the first luminescent layer 120, the mass content of the first sensitizer 121 ranges from 1% to 70%; the mass content of the first dye 123 ranges from 0.1% to 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; and / or, in the second luminescent layer 130, the mass content of the second sensitizer 131 ranges from 1% to 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.

[0064] The mass content of the first sensitizer 121 and the mass content of the second sensitizer 131 can be determined by methods including high performance liquid chromatography, elemental analysis, ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, etc.

[0065] Specifically, electrons and holes recombine in the first host material 122 or the first sensitizer 121 near the cathode layer 140 to form excitons; electrons and holes recombine in the second host material 132 or the second sensitizer 131 near the anode layer 110 to form excitons.

[0066] In the first main material 122, excitons in the singlet and triplet states respectively pass through... Energy is transferred to the first sensitizer 121 via Dexter energy transfer; excitons in the singlet and triplet states of the second host material 132 are respectively transferred through... Energy is transferred to Dexter and then to the second sensitizer 131.

[0067] In the first sensitizer 121, excitons in the singlet state reach the triplet state through intergap crossing (ISC); or excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC); in the second sensitizer 131, excitons in the singlet state reach the triplet state through intergap crossing (ISC).

[0068] The first sensitizer 121 achieves high efficiency and long-range... The energy transfer process transfers singlet exciton energy to the first dye 123 in the first luminescent layer 120; the second sensitizer 131 transmits energy via a highly efficient long-range... The energy transfer process transfers the triplet exciton energy to the first dye 123 in the first luminescent layer 120.

[0069] It is worth noting that, since the first sensitizer 121 includes a thermally activated delayed fluorescence material, excitons in the singlet state of the first sensitizer 121 reach the triplet state through intergap crossing (ISC), and excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC). All excitons in the triplet state transition to the singlet state, and then from the singlet state through... The energy transfer process transfers all excitons to the first dye 123 in the first luminescent layer 120, thereby enabling 100% utilization of the excitons in the first sensitizer 121. Excitons in the second sensitizer 131 can transition from singlet to triplet states; that is, all excitons in the singlet state transition to the triplet state, and then from the triplet state through… The energy transfer process transfers all exciton energy to the first dye 123 in the first light-emitting layer 120, thereby enabling the excitons of the second sensitizer 131 to be 100% utilized.

[0070] The first dye 123 achieves carrier recombination based on the energy transferred from the first sensitizer 121 and the second sensitizer 131, thereby emitting light.

[0071] Specifically, by Figure 4 As shown, the carrier recombination region A is located in a portion of the first light-emitting layer 120 near the cathode layer 140 of the organic electroluminescent device 100. This makes the carrier recombination region A of the organic electroluminescent device 100 closer to the center of the entire electroluminescent device. In this application, the photon release region is larger, which reduces the energy density per unit area, thereby reducing the probability of photon quenching and improving the lifetime and luminous efficiency of the organic electroluminescent device 100.

[0072] Figure 6 This is a schematic diagram of the structure of an organic electroluminescent device provided in another embodiment of this application. Figure 7This is an energy level diagram of an organic electroluminescent device provided in another embodiment of this application.

[0073] like Figure 6 and Figure 7 As shown, in some embodiments, the first light-emitting layer 120 includes a first host material 122 and a first sensitizer 121, and the second light-emitting layer 130 includes a second host material 132, a second sensitizer 131 and a second dye 133.

[0074] In the first luminescent layer 120, the mass content of the first sensitizer 121 ranges from 1% to 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; and / or, in the second luminescent layer 130, the mass content of the second sensitizer 131 ranges from 1% to 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; and the mass content of the second dye 133 ranges from 0.1% to 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0075] Specifically, electrons and holes recombine in the first host material 122 or the first sensitizer 121 near the cathode layer 140 to form excitons; electrons and holes recombine in the second host material 132 or the second sensitizer 131 near the anode layer 110 to form excitons.

[0076] In the first main material 122, excitons in the singlet and triplet states respectively pass through... Energy is transferred to the first sensitizer 121 via Dexter energy transfer; excitons in the singlet and triplet states of the second host material 132 are respectively transferred through... Energy is transferred to Dexter and then to the second sensitizer 131.

[0077] In the first sensitizer 121, excitons in the singlet state reach the triplet state through intergap crossing (ISC); or excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC); in the second sensitizer 131, excitons in the singlet state reach the triplet state through intergap crossing (ISC).

[0078] The first sensitizer 121 achieves high efficiency and long-range... The energy transfer process transfers singlet exciton energy to the second dye 133 in the second luminescent layer 130; the second sensitizer 131, through efficient long-range... The energy transfer process transfers the triplet exciton energy to the second dye 133 in the second luminescent layer 130.

[0079] It is worth noting that, since the first sensitizer 121 includes a thermally activated delayed fluorescence material, excitons in the singlet state of the first sensitizer 121 reach the triplet state through intergap crossing (ISC), and excitons in the triplet state reach the singlet state through reverse intergap crossing (RISC). All excitons in the triplet state transition to the singlet state, and then from the singlet state through... The energy transfer process transfers all excitons to the second dye 133 in the second luminescent layer 130, thereby enabling 100% utilization of the excitons in the first sensitizer 121. Excitons in the second sensitizer 131 can transition from singlet to triplet states; that is, all excitons in the singlet state transition to the triplet state, and then from the triplet state through… The energy transfer process transfers all excitons to the second dye 133 in the second light-emitting layer 130, thereby enabling the excitons of the second sensitizer 131 to be 100% utilized.

[0080] The second dye 133 achieves carrier recombination based on the energy transferred from the first sensitizer 121 and the second sensitizer 131, thereby emitting light.

[0081] Specifically, by Figure 6 As shown, the carrier recombination region A is located in a portion of the second light-emitting layer 130 near the anode layer 110 of the organic electroluminescent device 100. This makes the carrier recombination region A of the organic electroluminescent device 100 closer to the center of the entire electroluminescent device. In this application, the photon release region is larger, which reduces the energy density per unit area, thereby reducing the probability of photon quenching and improving the lifetime and luminous efficiency of the organic electroluminescent device 100.

[0082] Figure 8 This is a schematic diagram of the specific structure of an organic electroluminescent device provided in another embodiment of this application. For example... Figure 8 As shown, in some embodiments, the first light-emitting layer 120 includes a first carrier recombination region 124, and the second light-emitting layer 130 includes a second carrier recombination region 134. The first carrier recombination region 124 is located in a portion of the first light-emitting layer 120 near the cathode layer 140, and the second carrier recombination region 134 is located in a portion of the second light-emitting layer 130 near the anode layer 110.

[0083] Optionally, such as Figure 8 As shown, the first carrier recombination region 124 and the second carrier recombination region 134 are in contact. It is worth noting that the first carrier recombination region 124 and the second carrier recombination region 134 may not be in contact. When the first light-emitting layer 120 is in contact with the second light-emitting layer 130, the first carrier recombination region 124 and the second carrier recombination region 134 are in contact.

[0084] In some embodiments, the thickness of the first light-emitting layer 120 is in the range of 5nm-80nm, such as 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, etc.; and / or, the thickness of the second light-emitting layer 130 is in the range of 5nm-80nm, such as 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, etc.

[0085] Figure 9 This is a schematic diagram of the specific structure of an organic electroluminescent device provided in another embodiment of this application. Figure 9 The organic electroluminescent device shown is Figure 2 , Figure 4 or Figure 6 The difference in the illustrated organic electroluminescent device is that the organic electroluminescent device 100 further includes an intermediate layer 150 located between the first light-emitting layer 120 and the second light-emitting layer 130. Optionally, the thickness of the intermediate layer 150 ranges from 0.5 nm to 30 nm, such as 0.5 nm, 1 nm, 10 nm, 20 nm, 30 nm, etc. The first carrier recombination region 124 is located on the side of the intermediate layer 150 near the cathode layer 140, and the second carrier recombination region 134 is located on the side of the intermediate layer 150 near the anode layer 110.

[0086] Optionally, the material of the intermediate layer 150 is the same as that of the first main material 122 or the second main material 132.

[0087] Figure 10 This is a schematic diagram illustrating the specific structure of an organic electroluminescent device according to another embodiment of this application. For example... Figure 10 As shown, the organic electroluminescent device 100 further includes a hole transport region 160 and an electron transport region 170. The hole transport region 160 is located between the anode layer 110 and the first light-emitting layer 120, and the electron transport region 170 is located between the cathode layer 140 and the second light-emitting layer 130.

[0088] Optionally, the hole transport region 160 includes a hole transport layer 162, or the hole transport region 160 includes a hole injection layer 161 and a hole transport layer 162 stacked sequentially along the direction away from the anode layer 110; or the hole transport region 160 includes a hole injection layer 161, a hole transport layer 162 and an electron blocking layer 163 stacked sequentially along the direction away from the anode layer 110.

[0089] The hole injection layer 161 may include one or more of hexacyanohexaazatriphenylene (HAT-CN), copper phthalocyanine (CuPc), and titanium phthalocyanine (TiOPc); the hole transport layer 162 may include one or more of N,N'-bis(naphthyl-1-yl)-N,N'-bis(phenyl)benzidine (NPB), polyvinylcarbazole (PVK), and 1,1-bis[(di-4-toluamide)phenyl]cyclohexane (TAPC); and the electron blocking layer 163 may include 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), 4,4'-bis(carbazole-9-yl)biphenyl (CBP), and 1,3-bis(carbazole-9-yl)benzene (mCP).

[0090] It should be noted that the materials of the hole injection layer 161, hole transport layer 162, and electron blocking layer 163 are merely illustrative examples, and this application does not limit the materials of the hole injection layer 161, hole transport layer 162, and electron blocking layer 163.

[0091] Optionally, the electron transport region 170 includes an electron transport layer 172, or the electron transport region 170 includes an electron injection layer 171 and an electron transport layer 172 stacked sequentially along the direction away from the cathode layer 140; or the electron transport region 170 includes an electron injection layer 171, an electron transport layer 172, and a hole blocking layer 173 stacked sequentially along the direction away from the cathode layer 140. The hole blocking layer 173 may include one or more of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), and tris(8-hydroxyquinoline)aluminum (Alq3); the electron transport layer 172 may include one or more of zinc oxide (ZnO) and titanium dioxide (TiO2); and the electron injection layer 171 may include one or more of lithium fluoride (LiF), cesium carbonate (Cs2CO3), and magnesium-silver alloy.

[0092] It should be noted that the materials of the hole blocking layer 173, the electron transport layer 172, and the electron injection layer 171 are merely illustrative examples, and this application does not limit the materials of the hole blocking layer 173, the electron transport layer 172, and the electron injection layer 171.

[0093] Hole injection layer 161 is used to lower the potential barrier between anode layer 110 and hole transport layer 162, promoting efficient hole injection from anode layer 110, and hole transport layer 162 transports holes to first light-emitting layer 120 and second light-emitting layer 130. Electron injection layer 171 is used to lower the potential barrier between cathode layer 140 and electron transport layer 172, promoting efficient electron injection from cathode layer 140, and electron transport layer 172 transports electrons to first light-emitting layer 120 and second light-emitting layer 130. Electron blocking layer 163 is used to block electron diffusion into hole transport layer 162, and hole blocking layer 173 is used to block hole diffusion into electron transport layer 172.

[0094] In some embodiments, the light-emitting device 100 includes an anode layer 110, a plurality of light-emitting layers and a cathode layer 140 stacked sequentially, each light-emitting layer including the aforementioned first light-emitting layer 120 and second light-emitting layer 130, and a charge generation layer is disposed between two adjacent light-emitting layers.

[0095] In this embodiment, by setting a first light-emitting layer 120 and a second light-emitting layer 130, with the first light-emitting layer 120 close to the anode layer 110 and the second light-emitting layer 130 close to the cathode layer 140, the first sensitizer 121 in the first light-emitting layer 120 includes a thermally activated delayed fluorescence material, and the second sensitizer 131 in the second light-emitting layer 130 includes a phosphorescent material, thereby causing the carrier recombination region A of the first light-emitting layer 120 to be located in a portion of the first light-emitting layer 120 close to the cathode layer 140 of the organic electroluminescent device 100, and causing the second light-emitting layer 130 to be located close to the cathode layer 140 of the organic electroluminescent device 100, the second light-emitting layer 120 to be located close to the cathode layer 140 of the organic electroluminescent device 100, thereby causing the second light-emitting layer 120 to be located close to the cathode layer 140 of the organic electroluminescent device 100, and causing the second light-emitting layer 130 to be located close to the cathode layer 140 of the organic electroluminescent device 100, ... the second light-emitting layer 130 to be located close to the cathode layer 140 of the organic electroluminescent device 100, and the second light-emitting layer 130 to be located close to the cathode layer 140 of the organic electroluminescent device 100, and the second light-emitting layer The carrier recombination region A of the light-emitting layer 130 is located in a portion of the second light-emitting layer 130 near the anode layer 110 of the organic electroluminescent device 100. This makes the carrier recombination region A of the organic electroluminescent device 100 closer to the center of the entire electroluminescent device, avoiding shrinking the photon release area. In this application, the photon release area is relatively large, reducing the energy density per unit area, thereby reducing the probability of photon quenching and improving the lifetime and luminous efficiency of the organic electroluminescent device 100, enabling 100% utilization of exciton energy.

[0096] Figure 11 This is a schematic diagram of the structure of a display panel provided in another embodiment of this application. For example... Figure 11 As shown, this application provides a display panel 1100, including the light-emitting device 100 mentioned in any of the above embodiments.

[0097] Display panel 1100 is a product with image display capabilities. For example, display panel 1100 can be used to display static images, such as pictures or photographs. Display panel 1100 can also be used to display dynamic images, such as videos.

[0098] The display panel 1100 can be a laptop, mobile phone, handheld or portable computer, camera, camcorder, in-vehicle smart central control screen, calculator, smartwatch, GPS navigator, electronic photo, electronic billboard or sign, projector, etc.

[0099] Display panel 1100 includes the display panel provided in any of the above embodiments. The display panel may be an organic light-emitting diode display panel or a quantum dot electroluminescent display panel.

[0100] In addition, the display panel 1100 can also function as a camera, video recorder, fingerprint sensor, and facial recognition device. Accordingly, the display panel 1100 also includes at least one functional module for implementing the above functions, such as an under-display camera or an under-display fingerprint sensor.

[0101] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0102] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0103] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0104] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0105] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0106] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, 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 this invention should be included within the scope of protection of this invention.

Claims

1. A light-emitting device, characterized in that, include: An anode layer, a first light-emitting layer, a second light-emitting layer, and a cathode layer are stacked sequentially; wherein, The first light-emitting layer includes a first sensitizer, and the second light-emitting layer includes a second sensitizer. The first sensitizer includes a thermally activated delayed material, and the second sensitizer includes a phosphorescent material. The first light-emitting layer further includes a first host material, and the second light-emitting layer further includes a second host material; The LUMO level of the first sensitizer is deeper than the LUMO level of the first host material, and / or the HOMO level of the second sensitizer is shallower than the HOMO level of the second host material; The triplet energy level of the first host material is greater than or equal to the triplet energy level of the first sensitizer; and / or, the triplet energy level of the second host material is greater than or equal to the triplet energy level of the second sensitizer; The energy difference between the triplet energy level of the first host material and the triplet energy level of the first sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV; and / or, the energy difference between the triplet energy level of the second host material and the triplet energy level of the second sensitizer is greater than or equal to 0 eV and less than or equal to 0.5 eV.

2. The light-emitting device according to claim 1, characterized in that, At least one of the first light-emitting layer and the second light-emitting layer comprises a dye.

3. The light-emitting device according to claim 2, characterized in that, The first light-emitting layer includes a first dye; and / or, the second light-emitting layer includes a second dye, wherein the material of the first dye and the material of the second dye are the same.

4. The light-emitting device according to claim 3, characterized in that, The singlet energy level of the first host material is greater than or equal to the singlet energy level of the first dye; and / or, the singlet energy level of the second host material is greater than or equal to the singlet energy level of the second dye.

5. The light-emitting device according to claim 4, characterized in that, The difference between the singlet energy level of the first host material and the singlet energy level of the first dye is greater than or equal to 0 eV and less than or equal to 0.5 eV; and / or, the difference between the singlet energy level of the second host material and the singlet energy level of the second dye is greater than or equal to 0 eV and less than or equal to 0.5 eV.

6. The light-emitting device according to claim 1, characterized in that, The first main material comprises a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone, and sulfone; and / or the second main material is a compound containing at least one group selected from the group consisting of phenylene, anthracene, naphthyl, phenanthrene, triazine, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone, and sulfone.

7. The light-emitting device according to claim 1, characterized in that, The first main material and the second main material are the same.

8. The light-emitting device according to claim 2, characterized in that, The dyes include fluorescent dyes.

9. The light-emitting device according to claim 3, characterized in that, The first light-emitting layer includes a first dye, and the second light-emitting layer includes a second dye.

10. The light-emitting device according to claim 9, characterized in that, In the first luminescent layer, the mass content of the first sensitizer ranges from 1% to 70%; the mass content of the first dye ranges from 0.1% to 10%; and / or, in the second luminescent layer, the mass content of the second sensitizer ranges from 1% to 70%; the mass content of the second dye ranges from 0.1% to 10%.

11. The light-emitting device according to claim 3, characterized in that, In the first luminescent layer, the mass content of the first sensitizer ranges from 1% to 70%; the mass content of the first dye ranges from 0.1% to 10%; and / or, in the second luminescent layer, the mass content of the second sensitizer ranges from 1% to 70%.

12. The light-emitting device according to claim 3, characterized in that, In the first luminescent layer, the mass content of the first sensitizer ranges from 1% to 70%; and / or, in the second luminescent layer, the mass content of the second sensitizer ranges from 1% to 70%; and the mass content of the second dye ranges from 0.1% to 10%.

13. The light-emitting device according to claim 1, characterized in that, The thickness of the first light-emitting layer ranges from 5 nm to 80 nm; and / or, the thickness of the second light-emitting layer ranges from 5 nm to 80 nm.

14. The light-emitting device according to claim 1, characterized in that, The light-emitting device further includes an intermediate layer located between the first light-emitting layer and the second light-emitting layer.

15. The light-emitting device according to claim 14, characterized in that, The material of the intermediate layer is the same as the first main material or the second main material.

16. The light-emitting device according to claim 14, characterized in that, The thickness of the intermediate layer ranges from 0.5 nm to 30 nm.

17. The light-emitting device according to claim 1, characterized in that, It also includes a hole transport region and an electron transport region, wherein the hole transport region is located between the anode layer and the first light-emitting layer, and the electron transport region is located between the cathode layer and the second light-emitting layer.

18. The light-emitting device according to claim 17, characterized in that, The hole transport region includes a hole transport layer, or the hole transport region includes a hole injection layer and a hole transport layer stacked sequentially along the direction away from the anode layer; or the hole transport region includes a hole injection layer, a hole transport layer and an electron blocking layer stacked sequentially along the direction away from the anode layer.

19. The light-emitting device according to claim 17, characterized in that, The electron transport region includes an electron transport layer, or the electron transport region includes an electron injection layer and an electron transport layer stacked sequentially along the direction away from the cathode layer; or the electron transport region includes an electron injection layer, an electron transport layer and a hole blocking layer stacked sequentially along the direction away from the cathode layer.

20. A display panel, characterized in that, Includes the light-emitting device according to any one of claims 1 to 19.

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