Light-emitting device and display panel

Abstract

The invention provides a light-emitting device and a display panel. The organic light-emitting 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 thermal activation delay material, and the second sensitizer comprises a phosphorescent material. According to the technical scheme, the service life of the organic light-emitting device can be prolonged, and the light-emitting efficiency of the organic light-emitting device can be improved.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly relates to a light-emitting device and a display panel. Background Art

[0002] An organic light-emitting diode (OLED) is a device that achieves light emission through current driving. Specifically, an organic light-emitting diode 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 diodes. Summary of the Invention

[0003] To solve the above problems, embodiments of the present application provide a light-emitting device and a display panel.

[0004] In a first aspect, embodiments of the present application provide a light-emitting device, including: an anode layer, a first light-emitting layer, a second light-emitting layer, and a cathode layer that are sequentially stacked; wherein, the first light-emitting layer includes a first sensitizer, the second light-emitting layer includes a second sensitizer, the first sensitizer includes a thermally activated delayed fluorescence material, and the second sensitizer includes a phosphorescent material.

[0005] In combination 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 combination with the first aspect, at least one of the first light-emitting layer and the second light-emitting layer includes a dye; preferably, the first light-emitting layer includes a first dye; and / or, the second light-emitting layer includes 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 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; preferably, the first host material includes a compound containing at least one group among triphenylene, anthryl, naphthyl, phenanthryl, triazinyl, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone group, and phenylsulfonyl group; and / or, the second host material is a compound containing at least one group among triphenylene, anthryl, naphthyl, phenanthryl, triazinyl, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone group, and phenylsulfonyl group; preferably, the first host material and the second host material are the same; preferably, the dye includes a fluorescent dye.

[0007] In combination 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 range of the first sensitizer is 1% - 70%; the mass content range of the first dye is 0.1% - 10%; and / or, in the second light-emitting layer, the mass content range of the second sensitizer is 1% - 70%; the mass content range of the second dye is 0.1% - 10%.

[0008] In combination 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 range of the first sensitizer is 1% - 70%; the mass content range of the first dye is 0.1% - 10%; and / or, in the second light-emitting layer, the mass content range of the second sensitizer is 1% - 70%.

[0009] In combination 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 range of the first sensitizer is 1% - 70%; and / or, in the second light-emitting layer, the mass content range of the second sensitizer is 1% - 70%; the mass content range of the second dye is 0.1% - 10%.

[0010] In combination with the first aspect, the thickness range of the first light-emitting layer is 5 nm - 80 nm; and / or, the thickness range of the second light-emitting layer is 5 nm - 80 nm.

[0011] In combination 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 that of the first host material or the second host material; preferably, the thickness range of the intermediate layer is 5 nm - 80 nm.

[0012] In combination with the first aspect, it further includes a hole transport region and an electron transport region. 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 in sequence 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 in sequence along 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 in sequence 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 in sequence along the direction away from the cathode layer.

[0013] An embodiment of the present application further provides a display panel, including the light-emitting device mentioned above.

[0014] The light-emitting device and the display panel provided by the present application have an anode layer, a first light-emitting layer, a second light-emitting layer, and a cathode layer stacked in sequence; wherein, the first light-emitting layer includes a first sensitizer, the second light-emitting layer includes a second sensitizer, the materials of the first sensitizer and the second sensitizer are different. Specifically, the first sensitizer includes a thermally activated delayed fluorescence material, and the second sensitizer includes a phosphorescent material, so that the carrier recombination region of the light-emitting device is close to the center position of the whole light-emitting device, avoiding shrinking the photon emission region. In the present application, the photon emission region is larger, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching, so as to improve the lifetime and luminous efficiency of the light-emitting device. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application.

[0016] Figure 2 It is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application.

[0017] Figure 3 It is an energy level diagram of a light-emitting device provided by an embodiment of the present application.

[0018] Figure 4 It is a schematic structural diagram of a light-emitting device provided by another embodiment of the present application.

[0019] Figure 5 It is an energy level diagram of a light-emitting device provided by another embodiment of the present application.

[0020] Figure 6 It is a schematic structural diagram of a light-emitting device provided by another embodiment of the present application.

[0021] Figure 7 It is an energy level diagram of a light-emitting device provided by another embodiment of the present application.

[0022] Figure 8 It is a schematic structural diagram of the specific structure of a light-emitting device provided by another embodiment of the present application.

[0023] Figure 9 It is a schematic structural diagram of the specific structure of a light-emitting device provided by another embodiment of the present application.

[0024] Figure 10 It is a schematic structural diagram of the specific structure of a light-emitting device provided by another embodiment of the present application.

[0025] Figure 11 It is a schematic structural diagram of a display panel provided by another embodiment of the present application.

[0026] Description of reference numerals:

[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 manners

[0028] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0029] Figure 1 It is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application. As Figure 1 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 that are sequentially stacked.

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

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

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

[0033] The first sensitizer includes a thermally activated delayed 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 light-emitting layer 120 is close to the anode layer 110, and the second light-emitting layer 130 is close to the cathode layer 140. After applying a voltage, the thermally activated delayed fluorescence sensitizer (TADF Sensitizer, TS) in the first light-emitting layer 120 captures electrons in the device, making the carrier recombination region of the first light-emitting layer 120 located in a partial region of the first light-emitting layer 120 close to the cathode layer 140 of the organic electroluminescent device 100; the phosphorescent sensitizer (Phosphorescent Sensitizer, PS) in the second light-emitting layer 130 captures holes in the device, making the carrier recombination region of the second light-emitting layer 130 located in a partial region of the second light-emitting layer 130 close to the anode layer 110 of the organic electroluminescent device 100, thereby making the carrier recombination region of the organic electroluminescent device 100 close to the center position of the overall electroluminescent device, avoiding shrinking the photon release region. In this application, the photon release region is large, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching, so as to improve the lifespan 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 materials of the first dye and the second dye are the same.

[0037] It should be noted 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. 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, the measurement methods of the triplet energy level can include low-temperature phosphorescence spectroscopy, energy transfer method, photoacoustic calorimetry, electron paramagnetic resonance method, etc. The measurement methods of the singlet energy level can include fluorescence spectroscopy, excited-state absorption spectroscopy, etc. The measurement methods of the difference between the singlet energy level and the triplet energy level include: fluorescence and phosphorescence spectroscopy coupling method, transient fluorescence / phosphorescence lifetime analysis method, quantum chemical calculation method, etc. It should be noted that this application does not specifically limit the measurement methods of the triplet energy level, the singlet energy level, and the difference between the singlet energy level and the triplet energy level.

[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) that are not occupied by electrons.

[0042] In the first light-emitting layer 120, since the LUMO energy level of TS is deeper than the LUMO energy level of the first host material, the electron transport process encounters a large energy level step (energy barrier), resulting in a low electron mobility. Electrons accumulate at the interface near the cathode layer 140, forming a localized high-concentration electron region. The diffusion movement 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 partial region of the first light-emitting layer 120 close to 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, a large energy level step (energy barrier) is encountered during the hole transport process, resulting in a low hole mobility. The holes accumulate at the interface near the anode layer 110, forming a localized high-concentration hole region. The diffusion motion 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 partial region of the second light-emitting layer 130 close to the anode layer 110 of the organic electroluminescent device 100.

[0044] Optionally, 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, such as 0 eV, 0.20 eV, 0.30 eV, 0.40 eV, 0.50 eV, etc.; 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, such as 0 eV, 0.30 eV, 0.50 eV, etc. Within this energy level difference range, the triplet energy of the first host can be effectively transferred to the triplet of the first sensitizer through the Dexter energy transfer path, and the triplet energy of the second host can be effectively transferred to the triplet of the second sensitizer through the Dexter energy transfer path.

[0045] Optionally, 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, such as 0 eV, 0.30 eV, 0.50 eV, etc.; 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, such as 0 eV, 0.30 eV, 0.50 eV, etc. Within this energy level difference range, the singlet energy of the first host can be effectively transferred to the singlet of the first sensitizer through the energy transfer path, and the singlet energy of the second host can be effectively transferred to the singlet of the second sensitizer through the energy transfer path.

[0046] Optionally, the first host material 122 includes a compound containing at least one group among triphenylene, anthryl, naphthyl, phenanthryl, triazinyl, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone group, and phenylsulfonyl group; and / or the second host material 132 is a compound containing at least one group among triphenylene, anthryl, naphthyl, phenanthryl, triazinyl, pyridine, pyrimidine, pyrazine, pyridazine, benzophenone group, and phenylsulfonyl group.

[0047] Optionally, the first host material 122 and the second host 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 exciplex.

[0050] Figure 2 It is a schematic structural diagram of an organic electroluminescent device provided by an embodiment of the present application. Figure 3 It is an energy level diagram of an organic electroluminescent device provided by an embodiment of the present application.

[0051] As Figure 2 and Figure 3 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 materials of the first dye 123 and the second dye 133 are the same.

[0053] Among them, in the first light-emitting layer 120, the mass content range of the first sensitizer 121 is 1% - 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; the mass content range of the first dye 123 is 0.1% - 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; and / or, in the second light-emitting layer 130, the mass content range of the second sensitizer 131 is 1% - 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; the mass content range of the second dye 133 is 0.1% - 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

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

[0055] The singlet and triplet excitons in the first host material 122 transfer energy to the first sensitizer 121 through and Dexter energy transfer respectively; the singlet and triplet excitons in the second host material 132 transfer energy to the second sensitizer 131 through and Dexter energy transfer respectively.

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

[0057] The first sensitizer 121 transfers the singlet exciton energy 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 through an efficient long-range energy transfer process; the second sensitizer 131 transfers the triplet exciton energy 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 through an efficient long-range energy transfer process.

[0058] It should be noted that since the first sensitizer 121 includes a thermally activated delayed fluorescence material, excitons in the singlet state in the first sensitizer 121 reach the triplet state through intersystem crossing (ISC), and excitons in the triplet state reach the singlet state through the reverse intersystem crossing process (RISC). All excitons in the triplet state transition to the singlet state, and then from the singlet state through an energy transfer process, all excitons are transferred 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, so that the excitons of the first sensitizer 121 can be 100% utilized. Excitons in the second sensitizer 131 can transition from the singlet state to the triplet state, that is, all excitons in the singlet state transition to the triplet state, and then from the triplet state through an energy transfer process, all excitons are transferred 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, so that the excitons of the second sensitizer 131 can also be 100% utilized.

[0059] The first dye 123 realizes carrier recombination according to the energy transferred from the first sensitizer 121 and the second sensitizer 131, and then emits light; the second dye 133 realizes carrier recombination according to the energy transferred from the first sensitizer 121 and the second sensitizer 131, and then emits light.

[0060] Specifically, by Figure 2As shown, the carrier recombination region A is located in a partial region of the first light-emitting layer 120 close to the cathode layer 140 of the organic electroluminescent device 100 and a partial region of the second light-emitting layer 130 close to the anode layer 110 of the organic electroluminescent device 100, so that the carrier recombination region A of the organic electroluminescent device 100 is close to the center position of the overall electroluminescent device. In this application, the carrier recombination region is relatively large, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching, so as to improve the lifespan and luminous efficiency of the organic electroluminescent device 100.

[0061] Figure 4 It is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of this application. Figure 5 It is an energy level diagram of an organic electroluminescent device provided by another embodiment of this application.

[0062] As Figure 4 and Figure 5 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] Among them, in the first light-emitting layer 120, the mass content range of the first sensitizer 121 is 1% - 70%; the mass content range of the first dye 123 is 0.1% - 10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; and / or, in the second light-emitting layer 130, the mass content range of the second sensitizer 131 is 1% - 70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.

[0064] Among them, the mass contents of the first sensitizer 121 and the second sensitizer 131 can be determined by means 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 a part of the first host material 122 or the first sensitizer 121 close to the cathode layer 140 to form excitons; electrons and holes recombine in a part of the second host material 132 or the second sensitizer 131 close to the anode layer 110 to form excitons.

[0066] The singlet and triplet excitons in the first host material 122 transfer energy to the first sensitizer 121 through and Dexter energy transfer respectively; the singlet and triplet excitons in the second host material 132 transfer energy to the second sensitizer 131 through And Dexter energy transfer to transfer energy to the second sensitizer 131.

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

[0068] The first sensitizer 121 transfers the singlet exciton energy to the first dye 123 in the first light-emitting layer 120 through an efficient long-range energy transfer process; the second sensitizer 131 transfers the triplet exciton energy to the first dye 123 in the first light-emitting layer 120 through an efficient long-range energy transfer process.

[0069] It should be noted that since the first sensitizer 121 includes a thermally activated delayed fluorescence material, the singlet excitons in the first sensitizer 121 reach the triplet state through intersystem crossing (ISC), and the triplet excitons reach the singlet state through the reverse intersystem crossing process (RISC). All the triplet excitons jump to the singlet state, and then from the singlet state through the energy transfer process, all the excitons are transferred to the first dye 123 in the first light-emitting layer 120, so that the excitons of the first sensitizer 121 can be 100% utilized. The excitons in the second sensitizer 131 can jump from the singlet state to the triplet state, that is, all the singlet excitons jump to the triplet state, and then from the triplet state through the energy transfer process, all the exciton energies are transferred to the first dye 123 in the first light-emitting layer 120, so that the excitons of the second sensitizer 131 can also be 100% utilized.

[0070] The first dye 123 realizes carrier recombination according to the energy transferred from the first sensitizer 121 and the second sensitizer 131, and then emits light.

[0071] Specifically, as Figure 4 shown, the carrier recombination region A is located in a partial region of the first light-emitting layer 120 close to the cathode layer 140 of the organic electroluminescent device 100, so that the carrier recombination region A of the organic electroluminescent device 100 is close to the center position of the whole electroluminescent device. In this application, the photon release region is large, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching to improve the life and luminous efficiency of the organic electroluminescent device 100.

[0072] Figure 6 is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of this application. Figure 7It is the energy level diagram of the organic electroluminescent device provided by another embodiment of the present application.

[0073] As Figure 6 and Figure 7 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] Among them, in the first light-emitting layer 120, the mass content range of the first sensitizer 121 is 1%-70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; and / or, in the second light-emitting layer 130, the mass content range of the second sensitizer 131 is 1%-70%, such as 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.; the mass content range of the second dye 133 is 0.1%-10%, such as 0.1%, 1%, 2%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

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

[0076] The singlet and triplet excitons in the first host material 122 transfer energy to the first sensitizer 121 through and Dexter energy transfer respectively; the singlet and triplet excitons in the second host material 132 transfer energy to the second sensitizer 131 through and Dexter energy transfer respectively.

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

[0078] The first sensitizer 121 transfers the singlet exciton energy to the second dye 133 in the second light-emitting layer 130 through an efficient long-range energy transfer process; the second sensitizer 131 transfers the triplet exciton energy to the second dye 133 in the second light-emitting layer 130 through an efficient long-range energy transfer process.

[0079] It should be noted that since the first sensitizer 121 includes a thermally activated delayed fluorescence material, the excitons in the singlet state in the first sensitizer 121 reach the triplet state through intersystem crossing (ISC). The excitons in the triplet state reach the singlet state through the reverse intersystem crossing process (RISC). All the excitons in the triplet state transition to the singlet state, and then from the singlet state through an energy transfer process, all the excitons are transferred to the second dye 133 in the second light-emitting layer 130, so that the excitons of the first sensitizer 121 can be utilized 100%. The excitons in the second sensitizer 131 can transition from the singlet state to the triplet state, that is, all the excitons in the singlet state transition to the triplet state, and then from the triplet state through an energy transfer process, all the excitons are transferred to the second dye 133 in the second light-emitting layer 130, so that the excitons of the second sensitizer 131 can also be utilized 100%.

[0080] The second dye 133 realizes carrier recombination according to the energy transferred from the first sensitizer 121 and the second sensitizer 131, and then emits light.

[0081] Specifically, as Figure 6 shown, the carrier recombination region A is located in a partial region of the second light-emitting layer 130 close to the anode layer 110 of the organic electroluminescent device 100, so that the carrier recombination region A of the organic electroluminescent device 100 is close to the center position of the whole electroluminescent device. In this application, the photon release region is large, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching, so as to improve the lifespan and luminous efficiency of the organic electroluminescent device 100.

[0082] Figure 8 is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of this application. As Figure 8 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 partial region of the first light-emitting layer 120 close to the cathode layer 140, and the second carrier recombination region 134 is located in a partial region of the second light-emitting layer 130 close to the anode layer 110.

[0083] Optionally, as Figure 8 shown, the first carrier recombination region 124 and the second carrier recombination region 134 are in contact. It should be noted 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 range of the first light-emitting layer 120 is 5 nm - 80 nm, such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, etc.; and / or, the thickness range of the second light-emitting layer 130 is 5 nm - 80 nm, such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, etc.

[0085] Figure 9 It is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of the present application. Figure 9 The organic electroluminescent device shown in Figure 2 、 Figure 4 or Figure 6 The difference between the shown organic electroluminescent devices 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 range of the intermediate layer 150 is 0.5 nm - 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 close to the cathode layer 140, and the second carrier recombination region 134 contacts the side of the intermediate layer 150 close to the anode layer 110.

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

[0087] Figure 10 It is a schematic structural diagram of an organic electroluminescent device provided by another embodiment of the present application. As Figure 10 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 in sequence 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 in sequence along the direction away from the anode layer 110.

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

[0090] It should be noted that the materials of the hole injection layer 161, the hole transport layer 162, and the electron blocking layer 163 are only for exemplary illustration, and the present application does not limit the materials of the hole injection layer 161, the hole transport layer 162, and the 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 in sequence 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 in sequence along the direction away from the cathode layer 140. Among them, 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); 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 only for exemplary illustration, and the present application does not limit the materials of the hole blocking layer 173, the electron transport layer 172, and the electron injection layer 171.

[0093] The hole injection layer 161 is used to reduce the potential barrier between the anode layer 110 and the hole transport layer 162, facilitating the efficient injection of holes from the anode layer 110. The hole transport layer 162 transports holes to the first light-emitting layer 120 and the second light-emitting layer 130. The electron injection layer 171 is used to reduce the potential barrier between the cathode layer 140 and the electron transport layer 172, facilitating the efficient injection of electrons from the cathode layer 140. The electron transport layer 172 transports electrons to the first light-emitting layer 120 and the second light-emitting layer 130. The electron blocking layer 163 is used to block the diffusion of electrons to the hole transport layer 162, and the hole blocking layer 173 is used to block the diffusion of holes to the 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 that are sequentially stacked. Each light-emitting layer includes 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 providing the first light-emitting layer 120 and the 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. As a result, the carrier recombination region A of the first light-emitting layer 120 is located in a partial region of the first light-emitting layer 120 close to the cathode layer 140 of the organic electroluminescent device 100, and the carrier recombination region A of the second light-emitting layer 130 is located in a partial region of the second light-emitting layer 130 close to the anode layer 110 of the organic electroluminescent device 100. Furthermore, the carrier recombination region A of the organic electroluminescent device 100 is close to the central position of the overall electroluminescent device, avoiding the reduction of the photon release region. In this application, the photon release region is relatively large, reducing the energy density per unit area, thereby reducing the occurrence probability of photon quenching, improving the lifespan and luminous efficiency of the organic electroluminescent device 100, and enabling 100% utilization of exciton energy.

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

[0097] The display panel 1100 is a product with an image display function. For example, the display panel 1100 can be used to display static images, such as pictures or photos. The display panel 1100 can also be used to display dynamic images, such as videos.

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

[0099] The display panel 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.

[0100] In addition, the display panel 1100 can also have functions such as taking pictures, recording videos, fingerprint recognition, and face recognition. Correspondingly, the display panel 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.

[0101] 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 the purposes of illustration and easy understanding, rather than limitations, and the above details do not limit the present application to necessarily adopt the above specific details for implementation.

[0102] 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 manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The word "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.

[0103] 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.

[0104] The above 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 can be applied to other aspects without departing from the scope of the present application. Therefore, the present 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 foregoing description has been presented for purposes of illustration and description. In addition, this description is not intended to limit embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize some of their variations, modifications, alterations, additions, and sub-combinations.

[0106] The specific embodiments described above do not constitute a limitation on the protection scope of the present 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 principle of the present invention shall be included within the protection scope of the present 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 in sequence; wherein, The first light-emitting layer includes a first sensitizer, and the second light-emitting layer includes a second sensitizer, wherein the first sensitizer includes a thermally activated retardant material, and the second sensitizer includes a phosphorescent material.

2. The light emitting device according to claim 1, characterized in that: The first light-emitting layer further comprises a first host material, and the second light-emitting layer further comprises 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.

3. The light emitting device according to claim 2, characterized in that: At least one of the first light-emitting layer and the second light-emitting layer includes a dye; Preferably, 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 is the same as the material of the second dye; 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 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; Preferably, the first host material comprises a compound containing at least one of triphenylene, anthracene, naphthyl, phenanthryl, triazine, pyridine, pyrimidine, pyrazine, pyridazine, phenone and phenylsulfone groups; and / or the second host material is a compound containing at least one of triphenylene, anthracene, naphthyl, phenanthryl, triazine, pyridine, pyrimidine, pyrazine, pyridazine, phenone and phenylsulfone groups; Preferably, the first host material and the second host material are the same; Preferably, the dye comprises a fluorescent dye.

4. The light emitting device according to claim 1, characterized in that: The first light-emitting layer further comprises a first host material and a first dye, and the second light-emitting layer further comprises a second host material and a second dye; Preferably, the material of the first dye is the same as the material of the second dye; 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%.

5. The light emitting device according to claim 1, characterized in that: 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%.

6. The light emitting device according to claim 1, characterized in that: The first light-emitting layer further comprises a first host material, and the second light-emitting layer further comprises a second host material and a second dye; Preferably, in the first light-emitting layer, the mass content of the first sensitizer is in the range of 1%-70%; and / or, in the second light-emitting layer, the mass content of the second sensitizer is in the range of 1%-70%; and the mass content of the second dye is in the range of 0.1%-10%.

7. The light emitting device according to claim 1, characterized in that: The thickness of the first light-emitting layer is in the range of 5nm-80nm; and / or the thickness of the second light-emitting layer is in the range of 5nm-80nm.

8. The light emitting device according to claim 1, characterized in that: The light emitting device further comprises an intermediate layer between the first light emitting layer and the second light emitting layer; Preferably, the first light-emitting layer further comprises a first host material, the second light-emitting layer further comprises 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 0.5 nm to 30 nm.

9. 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; 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 in sequence in a 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 in sequence in a 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 in sequence in a 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 in sequence in a direction away from the cathode layer.

10. A display panel, characterized in that: A light emitting device comprising any one of claims 1 to 9.

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