An organic light emitting device and display apparatus

Abstract

The application relates to an organic light-emitting device and a display device, the organic light-emitting device comprising an anode layer and a cathode layer arranged oppositely, and an electron blocking layer, a first light-emitting layer and a second light-emitting layer arranged in layers between the anode layer and the cathode layer, the electron blocking layer being located between the anode layer and the first light-emitting layer, the first light-emitting layer being located between the electron blocking layer and the cathode layer, and the three layers being sequentially and adjacently arranged; a triplet energy level of the first host material being T1 Host1 , a triplet energy level of the second host material being T1 Host2 , a triplet energy level of the electron blocking layer being T1 Prime , T1 Host1 , T1 Host2 and T1 Prime satisfying an energy level relationship shown in the following formula: |T1 prime | >= |T1 Host2 | + 0.4 >= |T1 Host1 | > |T1 Host2 |. The application can realize efficient utilization of triplet excitons, thereby being favorable to significantly improving the light-emitting efficiency and service life of the organic light-emitting device.

Description

Technical Field

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

[0002] In recent years, Organic Light Emitting Diode (OLED) display technology has gradually attracted more attention. Due to its characteristics such as active light emission, high brightness, high resolution, wide viewing angle, fast response speed, color saturation, thinness, low power consumption, and flexibility, it is hailed as the dream display and has become a popular mainstream display product in the current market.

[0003] Currently, in blue OLED devices, triplet-polaron quenching (TPQ) caused by excess carriers in the emissive layer makes it difficult to achieve the theoretical internal quantum efficiency of 62.5%. Device efficiency can typically be improved by compressing the recombination region of the emissive layer or by selecting high-efficiency blue fluorescent guest materials. However, progress in improving efficiency through high-efficiency blue fluorescent guest materials is slow and difficult to iterate; while compressing the recombination region leads to a severe trade-off between device efficiency and lifetime, which is detrimental to meeting the requirements for high white light efficiency and long lifetime OLED panels. Summary of the Invention

[0004] This application provides an organic light-emitting device and a display device that can achieve efficient utilization of triplet excitons, thereby significantly improving the luminous efficiency and lifespan of the organic light-emitting device.

[0005] To achieve the above objectives, according to a first aspect of this application, an organic light-emitting device is provided, comprising:

[0006] Anode layer;

[0007] A cathode layer is disposed opposite to the anode layer;

[0008] At least one light-emitting unit is disposed between the anode layer and the cathode layer; the at least one light-emitting unit includes a first light-emitting layer and a second light-emitting layer stacked and adjacent to each other, the first light-emitting layer being located on the side of the second light-emitting layer closer to the anode layer; the material of the first light-emitting layer includes a first main material, and the material of the second light-emitting layer includes a second main material;

[0009] An electron blocking layer is located on the side of the first light-emitting layer near the anode layer and is disposed adjacent to the first light-emitting layer;

[0010] The triplet energy level of the first host material is T1. Host1 The triplet energy level of the second host material is T1 Host2 The triplet energy level of the electron blocking layer is T1. Prime T1 Host1 T1 Host2 and T1 Prime Satisfying the energy level relationship shown in equation (1):

[0011] |T1 prime |≥|T1 Host2 |+0.4≥|T1 Host1 |>|T1 Host2 | (1).

[0012] According to a second aspect of this application, a display device is provided, the display device comprising the organic light-emitting device described above.

[0013] In the organic light-emitting device and display device of this application embodiment, at least one light-emitting unit in the organic light-emitting device is composed of a first light-emitting layer and a second light-emitting layer stacked and disposed adjacent to each other. The first light-emitting layer is disposed near the anode layer, and the second light-emitting layer is disposed near the cathode layer. The organic light-emitting device also includes an electron blocking layer disposed adjacent to the first light-emitting layer on the side of the first light-emitting layer near the anode layer. The triplet energy level of the electron blocking layer is higher than that of the first host material and the second host material, which is beneficial for blocking triplet excitons in the first and second light-emitting layers. At the same time, it can also reduce the impact of triplet excitons on the electron blocking layer, thereby slowing down the consumption and degradation of molecules in the first and second light-emitting layers, and thus helping to increase the service life of the organic light-emitting device. Furthermore, the triplet energy level of the first host material is higher than that of the second host material, which is beneficial for the transfer of triplet excitons from the high-concentration interface recombination region to the low-concentration exciton utilization region. On the one hand, it can reduce the annihilation of triplet excitons caused by high-concentration charge carriers, thereby improving the luminous efficiency of the device. On the other hand, it can significantly reduce the exciton density in the interface recombination region, thereby reducing the damage of excitons to molecules in the first and second light-emitting layers, and thus increasing the lifespan of the organic light-emitting device.

[0014] Therefore, this application modulates the triplet energy levels of the first host material of the first light-emitting layer, the second host material of the second light-emitting layer, and the electron blocking layer adjacent to the first light-emitting layer, so that the triplet energy levels of the electron blocking layer, the first host material, and the second host material satisfy the energy level relationship shown in equation (1), thereby achieving efficient utilization of triplet excitons, which is beneficial to significantly improving the luminous efficiency and lifespan of organic light-emitting devices.

[0015] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0018] Figure 1 This is a schematic diagram of the structure of an organic light-emitting device provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of carrier migration in an organic light-emitting device provided in an embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the structure of a display device provided in an embodiment of this application.

[0021] Explanation of reference numerals in the attached figures: 1. Organic light-emitting device; 2. Anode layer; 3. Cathode layer; 4. Light-emitting unit; 5. First light-emitting layer; 6. Second light-emitting layer; 7. Electron blocking layer; 8. Hole injection layer; 9. Hole transport layer; 10. Electron transport layer; 11. Electron injection layer; 12. Display device; 13. Array substrate; 14. Encapsulation layer; A. Exciton recombination region; B. Exciton utilization region. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0023] In organic electroluminescence (OIE), applying a voltage to the anode and cathode layers generates singlet and triplet excitons in the luminescent layer. Traditional fluorescent materials can only utilize singlet excitons for luminescence, with a theoretical upper limit of 25% for internal quantum efficiency. Triplet-Triplet Annihilation (TTA) type blue light-emitting host materials, however, can utilize triplet excitons. Through the TTA process, two triplet excitons interact and annihilate, producing a singlet exciton and a ground-state molecule. The generated singlet exciton can emit light, theoretically improving exciton utilization and thus increasing luminescence efficiency. Furthermore, Triplet-Triplet Fusion (TTF) type blue light-emitting host materials can also utilize triplet excitons. Through the TTF process, two triplet excitons interact and fuse to form a singlet exciton and a ground-state molecule. The generated singlet exciton can emit light, further improving exciton utilization and thus increasing luminescence efficiency.

[0024] Therefore, the TTA and TTF processes can convert triplet excitons into singlet excitons, allowing triplet excitons, which cannot emit light directly, to participate in light emission, thereby improving the internal quantum efficiency of OLED devices and breaking through the efficiency limitations of traditional fluorescent OLED devices.

[0025] However, in the light-emitting process of OLED devices, the theoretical generation ratio of singlet excitons to triplet excitons is 1:3. Because triplet excitons have a longer lifetime and higher energy, they are prone to non-radiative transitions and energy loss if not controlled. For example, if triplet excitons diffuse into other non-emitting layers, they will transfer energy to impurities or defects in these layers, causing energy dissipation in a non-radiative form and reducing the overall performance of the device. Furthermore, the accumulation of triplet excitons in non-emitting layers may cause adverse physical or chemical changes, such as material degradation and interface damage, thereby affecting the stability and lifetime of the device.

[0026] To address the above issues and further improve the luminous efficiency and lifespan of organic light-emitting devices (OLEDs), this application takes a TTF-type OLED as an example and improves the structure of the emitting layer by changing the conventional single-layer emitting layer to a double-layer emitting layer. Simultaneously, by modulating the triplet energy levels of the first host material of the first emitting layer, the second host material of the second emitting layer, and the electron blocking layer adjacent to the first emitting layer, triplet excitons are confined within both the first and second emitting layers. This allows triplet excitons to transfer from the high-concentration interfacial recombination region to the low-concentration exciton utilization region, thereby achieving efficient utilization of triplet excitons and significantly improving the luminous efficiency and lifespan of the OLED. See the following embodiments for details.

[0027] like Figure 1 As shown, this application provides an organic light-emitting device 1, which includes an anode layer 2 and a cathode layer 3 disposed opposite to each other, and at least one light-emitting unit 4 disposed between the anode layer 2 and the cathode layer 3. At least one light-emitting unit 4 includes a first light-emitting layer 5 and a second light-emitting layer 6 stacked and adjacent to each other. The first light-emitting layer 5 is located on the side of the second light-emitting layer 6 closer to the anode layer 2. The material of the first light-emitting layer 5 includes a first host material (Host 1), and the material of the second light-emitting layer 6 includes a second host material (Host 2).

[0028] like Figure 1 and Figure 2 As shown, the organic light-emitting device 1 further includes an electron blocking layer 7 disposed on the side of the first light-emitting layer 5 near the anode layer 2, and the electron blocking layer 7 is disposed adjacent to the first light-emitting layer 5. The triplet energy level of the first host material is T1. Host1 The triplet energy level of the second host material is T1. Host2 The triplet energy level of electron blocking layer 7 is T1. Prime T1 Host1 T1 Host2 and T1 Prime Satisfying the energy level relationship shown in equation (1):

[0029] |T1 prime |≥|T1 Host2 |+0.4≥|T1 Host1 |>|T1 Host2 | (1).

[0030] It should be noted that in equation (1), the unit of the triplet energy level is electron volt (eV).

[0031] Understandably, the triplet energy level of electron blocking layer 7 is higher than that of the first host material and the second host material, and the triplet energy level of the first host material is higher than that of the second host material. The maximum difference between the triplet energy levels of the first host material and the second host material is 0.4 eV, and the minimum difference between the triplet energy levels of electron blocking layer 7 and the second host material is also 0.4 eV. In other words, the energy difference between the triplet energy levels of the first host material and the second host material is relatively small, while the energy difference between the triplet energy levels of electron blocking layer 7 and the second host material is relatively large.

[0032] On the one hand, such as Figure 2As shown, the triplet energy level of the electron blocking layer 7 is greater than that of the first host material and the second host material, and the difference between the triplet energy level of the electron blocking layer 7 and the triplet energy level of the second host material is large. This can effectively block triplet excitons in the first light-emitting layer 5, thus confining the triplet excitons in the first light-emitting layer 5 and the second light-emitting layer 6. This can prevent triplet excitons from diffusing into or accumulating in the non-light-emitting layer (e.g., the electron blocking layer 7), thereby reducing energy loss in the non-light-emitting region and making the energy more concentrated for the light-emitting process. This achieves efficient utilization of triplet excitons, thereby improving the luminous efficiency of the organic light-emitting device. At the same time, it can also maintain the structural and performance stability of each layer of the organic light-emitting device 1 and extend the service life of the organic light-emitting device 1.

[0033] On the other hand, such as Figure 2 As shown, the triplet energy level of the first host material cannot be significantly higher than that of the second host material. This is because if the triplet energy level of the first host material is too high, it hinders the effective transfer of triplet excitons from the first light-emitting layer 5 to the second light-emitting layer 6, thus preventing effective separation of the exciton recombination region A and the exciton utilization region B. Controlling the energy difference between the triplet energy levels of the first and second host materials within 0.4 eV is more conducive to the transfer of triplet excitons, thereby facilitating the separation of the exciton recombination region A and the exciton utilization region B, and ultimately improving the utilization rate of triplet excitons. Simultaneously, the transfer of triplet excitons can significantly reduce the exciton density in the exciton recombination region A, thereby reducing damage to molecules in the first and second light-emitting layers 5 and 6, and thus increasing the lifespan of the organic light-emitting device 1.

[0034] Therefore, in this embodiment, by regulating the triplet energy levels of the first host material of the first light-emitting layer 5, the second host material of the second light-emitting layer 6, and the electron blocking layer 7 adjacent to the first light-emitting layer 5, the triplet energy levels of the electron blocking layer 7, the first host material, and the second host material satisfy the energy level relationship shown in equation (1), thereby achieving efficient utilization of triplet excitons, which is beneficial to significantly improving the luminous efficiency and lifespan of the organic light-emitting device 1.

[0035] In one specific embodiment, the first light-emitting layer 5 and the second light-emitting layer 6 emit light of the same color.

[0036] It should be noted that when multiple light-emitting units 4 are connected in series between the anode layer 2 and the cathode layer 3, at least one of the light-emitting units 4 is a double light-emitting layer. That is, when there are multiple light-emitting units 4 in the organic light-emitting device 1, some of the light-emitting units 4 are double light-emitting layers, and the other part of the light-emitting units 4 are single light-emitting layers; or, all the light-emitting units 4 are formed by stacking the first light-emitting layer 5 and the second light-emitting layer 6 as described in the embodiments of this application.

[0037] In some embodiments, the electron blocking layer 7, the first host material, and the second host material satisfy the energy level relationship shown in equation (2):

[0038] |LUMO prime |<|LUMO Host1 |≤|LUMO Host2 | (2);

[0039] Among them, LUMO prime LUMO Host1 and LUMO Host2 These represent the lowest unoccupied molecular orbital energy levels of electron blocking layer 7, the first host material, and the second host material, respectively.

[0040] It should be noted that the LUMO energy level of the electron blocking layer 7 is shallower than that of the first host material and the second host material, which is beneficial for blocking electrons in the first and second light-emitting layers and preventing energy leakage. Furthermore, when the second host material in the second light-emitting layer 6 has a deeper LUMO energy level than the first host material in the first light-emitting layer 5, electrons provided by the cathode layer 3 are more easily injected from the second light-emitting layer 6 into the first light-emitting layer 5. This facilitates the recombination of electrons and holes on the side of the first light-emitting layer 5 away from the second light-emitting layer 6 to form excitons, thus promoting the formation of an exciton recombination region close to the electron blocking layer 7.

[0041] Understandably, the deeper the LUMO level, the larger its absolute value; conversely, the shallower the LUMO level, the smaller its absolute value. Similarly, the deeper the HOMO level, the larger its absolute value; conversely, the shallower the HOMO level, the smaller its absolute value.

[0042] In some embodiments, the electron blocking layer 7, the first host material, and the second host material satisfy the energy level relationship shown in equation (3):

[0043] |HOMO Host1 |≥|HOMO Host2 |>|HOMO prime | (3);

[0044] Among them, HOMO prime HOMO Host1 and HOMO Host2 These represent the highest occupied molecular orbital energy levels of electron blocking layer 7, the first host material, and the second host material, respectively.

[0045] It should be noted that the HOMO energy level of the electron blocking layer 7 is shallower than that of the first and second host materials. This facilitates the entry of holes from the electron blocking layer 7 into the first light-emitting layer 5, allowing them to enter the host material molecules rather than the guest material molecules. This enables electrons and holes to recombine on the first host material, thus efficiently forming excitons and improving exciton recombination efficiency, which is beneficial for improving the luminous efficiency of organic light-emitting devices. Furthermore, because the host material has good chemical and thermal stability, it can maintain a relatively stable structure and performance during device operation. Therefore, the recombination of holes and electrons on the host material can reduce performance degradation caused by material changes, improving the stability and lifespan of the device.

[0046] In addition, when the first host material in the first light-emitting layer 5 has a deeper HOMO energy level than the second host material in the second light-emitting layer 6, the injection barrier when the hole provided by the anode layer 2 enters the first light-emitting layer 5 increases, thereby slowing down the hole injection rate. This is conducive to the recombination of electrons and holes on the side of the first light-emitting layer 5 away from the second light-emitting layer 6 to form excitons, that is, it is conducive to the formation of an exciton recombination region close to the electron blocking layer 7.

[0047] In some embodiments, the hole mobility μ of the first host material in the first light-emitting layer 5 Host1 The hole mobility μ of the second host material in the second light-emitting layer 6 is less than that in the second light-emitting layer 6. Host2 The hole transport rate in the first light-emitting layer 5 is relatively small, which increases the difference between the transport rates of holes and electrons in the first light-emitting layer 5. This makes the electron transport rate in the first light-emitting layer 5 even greater than the hole transport rate, which is conducive to the recombination of electrons and holes on the side of the first light-emitting layer 5 away from the second light-emitting layer 6 to form excitons.

[0048] It should be noted that, as Figure 2 As shown, the process of hole-electron recombination to form excitons can be called exciton recombination, and the region where this process occurs is called exciton recombination region A. When exciton recombination region A is close to the boundary of the light-emitting layer, it can also be called the interface recombination region. The TTF process refers to the process of triplet excitons fusing to form singlet excitons, and the region where the TTF process occurs is called the TTF region, i.e., the exciton utilization region B. Therefore, in the organic light-emitting device 1 provided in this application embodiment, the exciton recombination region A and the exciton utilization region B are separated, which can reduce or avoid the collision between excess charge carriers in the exciton recombination region A and triplet excitons in the exciton utilization region B, resulting in triplet exciton annihilation, thereby improving the luminous efficiency and lifespan of the organic light-emitting device 1.

[0049] In some embodiments, the triplet energy level T1 can be measured using low-temperature phosphorescence spectroscopy. For example, at low temperatures (typically 77 K, cooled to this temperature with liquid nitrogen), nonradiative transitions of the triplet state can be suppressed, and low-temperature phosphorescence emission is detected by photoexcitation. The tangent to the emission spectrum peak or the peak value of the emission spectrum is taken as the wavelength λ for calculating the triplet energy level T1, and the calculation formula is T1 = 1240 / λ. Of course, in other embodiments, the triplet energy level T1 can be obtained using quantum chemical calculations. For example, the electronic structure of the molecule can be calculated using DFT or TD-DFT to predict the energy levels S1 and T1. When using theoretical calculations, attention should be paid to the accuracy of the calculation method (e.g., using functionals such as B3LYP, M06-2X, etc.).

[0050] In some embodiments, the HOMO and LUMO energy levels can be measured using any one of X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), atmospheric photoemission spectroscopy (AC-3), cyclic voltammetry (CV), and ultraviolet-visible absorption spectroscopy (UV–Vis). Of course, quantum chemical methods, such as density functional theory (DFT), are also effective methods for calculating molecular orbital energy levels.

[0051] Understandably, both X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) belong to photoelectron spectroscopy (also known as ionization potential spectroscopy or escape function spectroscopy).

[0052] In some embodiments, hole mobility is measured as follows: an organic material is fabricated into a hole-only device (HOD), and then an impedance spectroscopy (IS) impedance meter is used to analyze the impedance response (such as dielectric relaxation or carrier diffusion) of the HOD device at different frequencies to extract its hole mobility. Of course, hole mobility can also be measured using the Hall effect method, time-of-flight (TOF) method, or field-effect transistor (FET) method.

[0053] In some embodiments, the thickness of the first light-emitting layer 5 is less than or equal to the thickness of the second light-emitting layer 6.

[0054] In one specific embodiment, the thickness of the first light-emitting layer 5 is greater than 0 and less than or equal to 150 angstroms. The thickness of the second luminescent layer 6 is greater than 0 and less than or equal to 190 angstroms.

[0055] In some embodiments, the thickness of the electron blocking layer 7 is greater than or equal to 10 angstroms and less than or equal to 150 angstroms.

[0056] Since the dual-emitting layer involves exciton energy transfer, this energy transfer is divided into Forster energy transfer and Dexter energy transfer. The Forster energy transfer distance is typically within... Within a certain range, the Dexter energy transfer distance is typically within... Furthermore, considering the spontaneous diffusion effect caused by excitons from high to low concentration, the thickness of the first luminescent layer 5 is controlled within [specific range]. The optimal range is determined by the thickness of the first light-emitting layer 5, the electron-blocking layer 7, and the second light-emitting layer 6. These thicknesses must be considered simultaneously; otherwise, the operating voltage of the organic light-emitting device 1 will be too high. Therefore, considering the trade-off between operating voltage and luminous efficiency, the thickness of the second light-emitting layer 6 is controlled within a certain range. Furthermore, the thickness of the electron blocking layer 7 is controlled within The range is most suitable.

[0057] Furthermore, by controlling the thickness of the first light-emitting layer 5 to be less than or equal to the thickness of the second light-emitting layer 6, it is beneficial for triplet excitons to transfer from the exciton recombination region A of the first light-emitting layer 5 to the second light-emitting layer 6, and to complete the TTF process in the second light-emitting layer 6, thereby realizing the separation of the exciton recombination region A and the exciton utilization region B.

[0058] In some embodiments, in order to at least satisfy the triplet energy level requirement shown in formula (1), the first host material includes at least one first cyclic group, and the second host material includes at least one second cyclic group; any two adjacent rings in the first cyclic group are interconnected by two shared adjacent atoms, and any two adjacent rings in the second cyclic group are interconnected by two shared adjacent atoms. The number of rings in at least one first cyclic group is greater than or equal to the number of rings in any one of the second cyclic groups.

[0059] In other words, the largest tandem ring structure in the first main material needs to be greater than or equal to the largest tandem ring structure in the second main material.

[0060] It should be noted that the number of rings in the first and second fused cyclic groups refers to the number of rings connected by two shared adjacent atoms. For example, the naphthyl group, phenanthrene group, anthracene group, and pyrene group are all fused cyclic groups. Among them, the naphthyl group has 2 rings, the phenanthrene group and the anthracene group have 3 rings, and the pyrene group has 4 rings.

[0061] It should be noted that the molecular structure design of organic materials needs to take into account the entire molecular skeleton, and cannot be limited to the structural design of the molecular core. Every part of the molecular skeleton contributes to the energy level.

[0062] In some embodiments, the number of first cyclohexane groups in the first host material is greater than or equal to the number of second cyclohexane groups in the second host material.

[0063] Of course, in other embodiments, when the number of rings in at least one first cyclic group is greater than or equal to the number of rings in any second cyclic group according to the energy level relationship described above, the number of first cyclic groups in the first host material may be less than the number of second cyclic groups in the second host material.

[0064] Understandably, the first and second host materials are different. The first host material can be a single compound or a mixture of two compounds. Similarly, the second host material can be a single compound or a mixture of two compounds.

[0065] In some embodiments, the first host material is selected from at least one of the compounds represented by general formula I and general formula II:

[0066]

[0067] Among them, R1 to R 20 It is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, and substituted or unsubstituted alkyl group.

[0068] Understandably, heteroaryl refers to a group formed when one or more carbon atoms in an aryl group are replaced by heteroatoms (such as nitrogen, oxygen, sulfur, etc.).

[0069] In some embodiments, R1 to R 10 The substituted group is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracel, substituted or unsubstituted trefyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted naphthuryl, wherein the substituted or unsubstituted substituted group includes protium atom, deuterium atom or tritium atom.

[0070] In some embodiments, R 11 To R 20 The substituted group is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted phenyl group, substituted or unsubstituted naphthyl group, substituted or unsubstituted benzofuranyl group, and substituted or unsubstituted naphthylfuranyl group, wherein the substituted or unsubstituted substituted group includes protium atom, deuterium atom or tritium atom.

[0071] In some embodiments, R1 is selected from any one or more combinations of phenyl, deuterated phenyl, trefyl, naphthyl, deuterated naphthyl, dibenzofuranyl, anthraceneyl and benzonaphthofuranyl;

[0072] R3, R4, R5, R7, and R8 are selected from hydrogen atoms or phenyl groups;

[0073] R6 is selected from any one or more combinations of hydrogen atoms, phenyl groups, and deuterated phenyl groups;

[0074] R2, R9 and R 10 Selected from hydrogen atoms.

[0075] It should be noted that deuterated phenyl means that at least one hydrogen atom in a phenyl group is replaced by a deuterium atom, and deuterated naphthyl means that at least one hydrogen atom in a naphthyl group is replaced by a deuterium atom.

[0076] In one specific embodiment, the compound represented by general formula I includes at least one of the following compounds:

[0077]

[0078]

[0079] In some embodiments, R 11 Selected from any one or more combinations of phenyl, naphthyl, biphenyl, deuterated phenyl, and deuterated naphthyl;

[0080] R 16 It is selected from any one or more combinations of phenyl, naphthyl, dibenzofuranyl, benzonaphthofuranyl, deuterated phenyl, deuterated biphenyl, deuterated dibenzofuranyl and deuterated benzonaphthofuranyl;

[0081] R 12 To R 15 and R 17 To R 20 It is selected from hydrogen atoms or deuterium atoms.

[0082] Understandably, deuterated biphenyl means that at least one hydrogen atom in a biphenyl group is replaced by a deuterium atom, deuterated dibenzofuranyl means that at least one hydrogen atom in a dibenzofuranyl group is replaced by a deuterium atom, and deuterated benzonaphthofuranyl means that at least one hydrogen atom in a benzonaphthofuranyl group is replaced by a deuterium atom.

[0083] In one specific embodiment, the compound represented by general formula II includes at least one of the following compounds:

[0084]

[0085]

[0086]

[0087] In some embodiments, the second host material is selected from at least one of the compounds represented by general formula II.

[0088] In a preferred embodiment, the first host material is selected from at least one of the compounds shown in BH1 to BH5, and the second host material is selected from the compound shown in BH0.

[0089]

[0090] It should be noted that by selecting appropriate first and second host materials from the compounds represented by general formulas I and II, it is beneficial to confine triplet excitons in the first luminescent layer 5 and the second luminescent layer 6, and a large number of excitons in the first luminescent layer 5 can be transferred to the second luminescent layer 6, thereby achieving high-efficiency utilization of excitons.

[0091] In some embodiments, the material of the first luminescent layer 5 further includes a first guest material, and the material of the second luminescent layer 6 further includes a second guest material. The first guest material and the second guest material are selected from any one of non-thermally activated delayed fluorescence materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials.

[0092] It should be noted that the first guest material and the second guest material can be the same or different; the first guest material and the second guest material are respectively doped into the first light-emitting layer 5 and the second light-emitting layer 6, so the content of the guest material in the light-emitting layer is very small.

[0093] In a preferred embodiment, the first guest material and the second guest material are selected from non-thermally activated delayed fluorescence materials. It is understood that non-thermally activated delayed fluorescence materials refer to ordinary fluorescent materials that differ from TADF.

[0094] In some embodiments, when the first guest material and the second guest material are selected from non-thermally activated delayed fluorescence materials, the first guest material and / or the second guest material are selected from at least one of the compounds represented by Formula III:

[0095]

[0096] Where X is selected from N, O, S or Se;

[0097] R 21 To R 25It is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, and substituted or unsubstituted alkyl group.

[0098] In one specific embodiment, the first guest material and / or the second guest material are selected from at least one of the following compounds:

[0099]

[0100]

[0101]

[0102] In some embodiments, the light emitted by the first light-emitting layer 5 and the second light-emitting layer 6 is any one of red light, green light, and blue light. That is, the organic light-emitting device 1 can be any one of a red light device, a green light device, and a blue light device.

[0103] In a preferred embodiment, the light emitted by the first light-emitting layer 5 and the second light-emitting layer 6 is blue light, that is, the organic light-emitting device 1 is a blue light device.

[0104] In some embodiments, the organic light-emitting device 1 further includes a hole injection layer 8 and a hole transport layer 9 disposed between the anode layer 2 and the electron blocking layer 7, and an electron transport layer 10 and an electron injection layer 11 disposed between the second light-emitting layer 6 and the cathode layer 3, wherein the hole transport layer 9 is disposed between the hole injection layer 8 and the electron blocking layer 7, and the electron injection layer 11 is located between the electron transport layer 10 and the cathode layer 3.

[0105] Of course, the organic light-emitting device 1 can also have other organic functional layers that are beneficial to improving luminous efficiency and lifespan between the anode layer 2 and the first light-emitting layer 5, as well as between the second light-emitting layer 6 and the cathode layer 3, or a light extraction layer CPL can be provided on the surface of the cathode layer 3 to improve light extraction efficiency.

[0106] In some embodiments, the organic light-emitting device 1 is an OLED device, but it is not limited thereto.

[0107] In some embodiments, the first light-emitting layer 5, the second light-emitting layer 6, and the electron blocking layer 7 in the organic light-emitting device 1 are prepared by vacuum evaporation or inkjet printing. Of course, other organic film layers in the organic light-emitting device 1 can also be prepared by vacuum evaporation or inkjet printing.

[0108] In this embodiment, at least one light-emitting unit 4 in the organic light-emitting device 1 is composed of a first light-emitting layer 5 and a second light-emitting layer 6 stacked and adjacent to each other. The first light-emitting layer 5 is disposed near the anode layer 2, and the second light-emitting layer 6 is disposed near the cathode layer 3. The anode layer 2 provides holes to the first light-emitting layer 5, and the cathode layer 3 provides electrons to the second light-emitting layer 6. Unlike conventional single-layer light-emitting layers, the light-emitting layer provided in this embodiment is a double-layer light-emitting layer, and the host materials in the double-layer light-emitting layers are different. The organic light-emitting device 1 also includes an electron blocking layer 7 located on the side of the first light-emitting layer 5 near the anode layer 2 and disposed adjacent to the first light-emitting layer 5. The triplet energy level of the electron blocking layer 7 is higher than that of the first host material and the second host material, which is beneficial for blocking triplet excitons in the first light-emitting layer 5 and the second light-emitting layer 6. At the same time, it can also reduce the impact of triplet excitons on the electron blocking layer 7, thereby slowing down the consumption and degradation of molecules in the first light-emitting layer 5 and the second light-emitting layer 6, and thus helping to increase the service life of the organic light-emitting device 1. Furthermore, the triplet energy level of the first host material is higher than that of the second host material, which is beneficial for triplet excitons to transfer from the high-concentration exciton recombination region to the low-concentration exciton utilization region B. On the one hand, it can reduce the annihilation of triplet excitons caused by high-concentration charge carriers, thereby improving the luminous efficiency of the device. On the other hand, it can significantly reduce the exciton density in the exciton recombination region, thereby reducing the damage of excitons to molecules in the first luminescent layer 5 and the second luminescent layer 6, and thus increasing the lifespan of the organic light-emitting device 1.

[0109] Therefore, this application modulates the triplet energy levels of the first host material of the first light-emitting layer 5, the second host material of the second light-emitting layer 6, and the electron blocking layer 7 adjacent to the first light-emitting layer 5, so that the triplet energy levels of the electron blocking layer 7, the first host material, and the second host material satisfy the energy level relationship shown in equation (1), thereby realizing the efficient utilization of triplet excitons, which is beneficial to significantly improving the luminous efficiency and service life of the organic light-emitting device 1.

[0110] This application also provides Comparative Examples 1, 2, and Examples 1 to 3. Comparative Examples 1 and 2 provide comparative devices OLED-ref1 and OLED-ref2, respectively. Examples 1 to 3 provide experimental devices OLED-1 to OLED-3. OLED-ref1, OLED-ref2, and OLED-1 to OLED-3 are all blue light devices, and the structures of these devices are similar to those in the aforementioned examples. Figure 1 The organic light-emitting device 1 shown has the same structure, except that the material of the first light-emitting layer 5 is different. The influence of the triplet energy levels of the electron blocking layer, the first light-emitting layer and the second light-emitting layer on the luminous efficiency and lifespan of the organic light-emitting device 1 was verified by comparative examples and embodiments.

[0111] In the embodiments of this application, the structures of OLED-ref1 and OLED-ref2, OLED-1 to OLED-3 provided in Comparative Examples 1, 2, and Examples 1 to 3 are ITO / HIL (HTL: PD, 3% / HTL, / Prime, / EML1(BH 1st :BD, 2%) / EML2(BH 2nd :BD, 2% / EICL, / ETL(ET:LiQ,50%) ) / Yb, / Mg:Ag, / CPL, Wherein, ITO represents indium tin oxide, i.e., the anode layer material; HIL represents the hole injection layer; PD represents the p-type dopant; HTL represents the hole transport layer; Prime represents the electron blocking material; EML1 represents the first light-emitting layer; and BH represents the first light-emitting layer. 1st BD represents the primary material, BD represents the secondary material, EML2 represents the secondary light-emitting layer, and BH represents the secondary light-emitting layer. 2nd The second main material is indicated by: EICL (Electron Injection and Hole Blocking Layer or Electron Injection Contact Layer); ETL (Electron Transport Layer); ET (Electron Transport Material); Yb (Ytterbium) represents the electron injection layer material or cathode modification material; Mg:Ag represents the cathode layer material; CPL represents the light extraction layer; 3% in HIL refers to the molar percentage of PD in the HIL material, and 2% in EML refers to the molar percentage of BD in EML1 or EML2.

[0112] The thickness of the electron blocking layer in the comparison devices OLED-ref1, OLED-ref2, and the experimental devices OLED-1 to OLED-3 is all... The electron blocking material for the comparative device OLED-ref1 and experimental devices OLED-1 to OLED-3 is Prime1, while the electron blocking material for the comparative device OLED-ref2 is Prime2. The first host material of the first emissive layer of the comparative device OLED-ref1 and experimental devices OLED-1 to OLED-3 is selected from compounds represented by formulas BH1 to BH4, respectively. The first host material of the first emissive layer of the comparative device OLED-ref2 is selected from a compound represented by BH5, and the thickness of the first emissive layer is uniform. The second host material of the second emissive layer in the comparative devices OLED-ref1 and OLED-ref2, and the experimental devices OLED-1 to OLED-3, were all selected from the compound shown in BH0, and the thickness of the second emissive layer was also [missing information].

[0113] Table 1 shows the chemical formulas of the electron blocking materials Prime1 and Prime2, as well as the guest material BD of the luminescent layer:

[0114]

[0115] It is understandable that OLED-ref1, OLED-ref2, OLED-1 to OLED-3 differ only in the main material of the first light-emitting layer, while the structures and materials of the other film layers are the same.

[0116] The test results of the triplet energy level T1 of the compounds shown in Comparative Examples 1, 2, and Examples 1 to 3 of this application, including electron blocking layers and compounds BH0 to BH5, are shown in Table 1. Specifically, the triplet energy level T1 of each compound was measured using low-temperature phosphorescence spectroscopy in the examples of this application.

[0117] Table 1

[0118]

[0119] As shown in Table 1, the triplet energy levels of the electron blocking layer (Prime 1) in OLED-ref 1 provided in Comparative Example 1 and OLED-1 to OLED-3 provided in Examples 1 to 3 are all greater than the triplet energy levels of the first host material and the second host material, and the difference between the triplet energy level of the electron blocking layer (Prime 1) and the triplet energy level of the second host material is 0.6 eV (i.e., greater than 0.4 eV). Specifically, the triplet energy level of the first host material in OLED-ref 1 provided in Comparative Example 1 is less than the triplet energy level of the second host material. The difference between the triplet energy levels of the first host material and the second host material in OLED-ref 2 provided in Comparative Example 2 is 0.2 eV (i.e., less than 0.4 eV), however, the triplet energy level of the electron blocking layer in OLED-ref 2 is less than the triplet energy level of the first host material. The triplet energy level of the first host material in OLED-1 provided in Example 1 is equal to the triplet energy level of the second host material. In Example 2, the triplet energy level difference between the first host material and the second host material in OLED-2 is 0.2 eV (i.e., less than 0.4 eV). In Example 3, the triplet energy level difference between the first host material and the second host material in OLED-3 is 0.4 eV.

[0120] The current-voltage (JV) characteristics of OLED-ref1 and OLED-ref2 provided in Comparative Examples 1 and 2, as well as OLED-1 to OLED-3 provided in Examples 1 to 3, were characterized using a characterization device. Important parameters such as luminous efficiency and lifetime were recorded, and the results are shown in Table 2. The device efficiency in Table 2 refers to the efficiency of organic light-emitting device 1 at 10 mA / cm². 2 The current efficiency and device lifetime of an organic light-emitting device (OLED) at 30 mA / cm² are discussed. 2 The time it takes for the brightness to decay to 97% of the initial brightness.

[0121] Specifically, the voltage in Table 2 refers to the voltage applied between the anode layer 2 and the cathode layer 3 of the organic light-emitting device 1, and the voltage and luminous efficiency are obtained by testing using the IVL automated optical testing system. The IVL automated optical testing system includes a PR735 spectrometer, a KEITHLEY 2420 DC power supply, and auxiliary tools such as fixtures.

[0122] Specifically, the luminous efficiency in Table 2 is calculated using equation (4):

[0123] CE=Lum*S / (I*Tr) (4);

[0124] Wherein, CE represents the luminous efficiency of organic light-emitting device 1; Lum represents the luminous brightness of organic light-emitting device 1; S represents the luminous area of ​​organic light-emitting device 1; I represents the current driving organic light-emitting device 1 to achieve the luminous brightness; and Tr represents the transmittance of the light-emitting side of organic light-emitting device 1.

[0125] Specifically, the lifespan in Table 2 was obtained by testing with an OLED lifespan testing system, which includes a KEITHLEY3706A DC power supply.

[0126] Table 2

[0127]

[0128]

[0129] As shown in Table 2, the voltage, luminous efficiency, and lifespan of Comparative Example 2 and Examples 1 to 3 are all referenced to the voltage, luminous efficiency, and lifespan of the OLED-ref provided in Comparative Example 1. Compared with the OLED-ref1 provided in Comparative Example 1, the operating voltage of OLED-1 to OLED-3 provided in Examples 1 to 3 of this application is improved. However, the luminous efficiency of OLED-1 and OLED-3 provided in Examples 1 to 3 is effectively improved, and the lifespan of OLED-1 and OLED-2 provided in Examples 1 and 2 is also effectively improved. This indicates that when the triplet energy levels of the electron blocking layer are both greater than the triplet energy levels of the first host material and the second host material, and the difference between the triplet energy levels of the electron blocking layer and the triplet energy levels of the second host material is greater than 0.4 eV, the luminous efficiency of the organic light-emitting device can be effectively improved. Furthermore, when the triplet energy level of the first host material is slightly higher than the triplet energy level of the second host material, the lifespan of the organic light-emitting device can be effectively improved.

[0130] Comparing Examples 2 and 3, it is evident that when the triplet energy level of the first host material in the organic light-emitting device is significantly higher than that of the second host material, the excessively high triplet energy level of the first host material hinders the efficient transfer of triplet excitons from the first emissive layer EML1 to the second emissive layer EML2. This negatively impacts the lifespan of the organic light-emitting device and may even lead to a decrease in its lifespan. Therefore, the triplet energy level of the first host material in the organic light-emitting device should be appropriately higher than that of the second host material to facilitate triplet exciton transfer.

[0131] Comparing Example 2 and Comparative Example 2, it can be seen that when the triplet energy level of the electron blocking layer is low and does not satisfy the energy level relationship shown in Equation (1), it is not conducive to improving the luminous efficiency and lifespan of the organic light-emitting device, but instead leads to a decrease in the luminous efficiency and lifespan of the organic light-emitting device.

[0132] As can be seen from the above, when the triplet energy levels of the electron blocking layer, the first host material, and the second host material satisfy the energy level relationship shown in equation (1), and the triplet energy levels of the first host material and the second host material are relatively close, the luminous efficiency and lifespan of the organic light-emitting device can be effectively improved.

[0133] like Figure 3 As shown, this application embodiment also provides a display device 12, which includes the organic light-emitting device 1 described in the above embodiments.

[0134] In some embodiments, the display device 12 further includes an array substrate 13 and an encapsulation layer 14. A driving circuit is provided in the array substrate 13, and a plurality of organic light-emitting devices 1 are disposed between the array substrate 13 and the encapsulation layer 14 and electrically connected to the driving circuit. It is understood that the driving circuit is used to provide driving voltages to the anode layer 2 and cathode layer 3 in the organic light-emitting devices 1, thereby achieving light emission.

[0135] In some embodiments, the display device 12 includes a red OLED device, a green OLED device, and a blue OLED device, at least one of which has the same structure as the organic light-emitting device 1 in the foregoing embodiments.

[0136] For example, in some embodiments, the light-emitting layers in the red OLED device, green OLED device and blue OLED device in the display device 12 are all the double-layer light-emitting layer structure described in the embodiments of this application; in other embodiments, the light-emitting layers in the red OLED device and green OLED device in the display device 12 are single-layer light-emitting layers, while the light-emitting layer in the blue OLED device is the double-layer light-emitting layer structure described in the embodiments of this application, but not limited thereto.

[0137] In this embodiment, since the luminous efficiency and lifespan of the organic light-emitting device 1 are improved, it is beneficial to improve the display effect of the display device 12 and extend the lifespan of the display device 12.

[0138] When the organic light-emitting device 1 is a blue TTA device or a blue TTF device, the luminous efficiency and lifespan of the device are effectively improved, which is beneficial to improving the white light efficiency of the display device 12, improving the stability of the display device 12, and also helping to improve the color lifespan of the display device 12.

[0139] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0140] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments. The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0141] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. An organic light-emitting device, characterized in that, include: Anode layer; A cathode layer is disposed opposite to the anode layer; At least one light-emitting unit is disposed between the anode layer and the cathode layer; At least one of the light-emitting units includes a first light-emitting layer and a second light-emitting layer stacked and disposed adjacent to each other, wherein the first light-emitting layer is located on the side of the second light-emitting layer closer to the anode layer; the material of the first light-emitting layer includes a first main material, and the material of the second light-emitting layer includes a second main material; An electron blocking layer is located on the side of the first light-emitting layer near the anode layer and is disposed adjacent to the first light-emitting layer; The triplet energy level of the first host material is T1. Host1 The triplet energy level of the second host material is T1. Host2 The triplet energy level of the electron blocking layer is T1. Prime T1 Host1 T1 Host2 and T1 Prime Satisfying the energy level relationship shown in equation (1): |T1 prime |≥|T1 Host2 |+0.4≥|T1 Host1 |>|T1 Host2 | (1).

2. The organic light-emitting device according to claim 1, characterized in that, The electron blocking layer, the first host material, and the second host material satisfy the energy level relationship shown in equation (2): |LIGHT prime |<|LIGHT Host1 |≤|LIGHT Host2 | (2); Among them, LUMO prime LUMO Host1 and LUMO Host2 These represent the lowest unoccupied molecular orbital energy levels of the electron blocking layer, the first host material, and the second host material, respectively.

3. The organic light-emitting device according to claim 1, characterized in that, The electron blocking layer, the first host material, and the second host material satisfy the energy level relationship shown in equation (3): |HOMO Host1 |≥|HOMO Host2 |>|HOMO prime | (3); Among them, HOMO prime HOMO Host1 and HOMO Host2 These represent the highest occupied molecular orbital energy levels of the electron blocking layer, the first host material, and the second host material, respectively.

4. The organic light-emitting device according to any one of claims 1 to 3, characterized in that, The first host material includes at least one first cyclic group, and the second host material includes at least one second cyclic group; any two adjacent rings in the first cyclic group are connected to each other by two shared adjacent atoms, and any two adjacent rings in the second cyclic group are connected to each other by two shared adjacent atoms. At least one of the first cyclic groups has a ring number greater than or equal to the ring number in any one of the second cyclic groups.

5. The organic light-emitting device according to claim 4, characterized in that, The number of the first cyclic groups in the first host material is greater than or equal to the number of the second cyclic groups in the second host material.

6. The organic light-emitting device according to claim 4, characterized in that, The first host material is selected from at least one of the compounds represented by general formula I and general formula II: Among them, R1 to R 20 It is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, and substituted or unsubstituted alkyl group.

7. The organic light-emitting device according to claim 6, characterized in that, R1 to R 10 The substituent is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracel, substituted or unsubstituted trefyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted naphthuryl, wherein the substituted or unsubstituted substituent includes protium atom, deuterium atom or tritium atom; R 11 To R 20 The substituted group is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted phenyl group, substituted or unsubstituted naphthyl group, substituted or unsubstituted benzofuranyl group, and substituted or unsubstituted naphthylfuranyl group, wherein the substituted or unsubstituted substituted group includes protium atom, deuterium atom or tritium atom.

8. The organic light-emitting device according to claim 7, characterized in that, R1 is selected from any one or more combinations of phenyl, deuterated phenyl, trefyl, naphthyl, deuterated naphthyl, dibenzofuranyl, anthraceneyl and benzonaphthofuranyl; R3, R4, R5, R7, and R8 are selected from hydrogen atoms or phenyl groups; R6 is selected from any one or more combinations of hydrogen atoms, phenyl groups, and deuterated phenyl groups; R2, R9 and R 10 Selected from hydrogen atoms.

9. The organic light-emitting device according to claim 7, characterized in that, R 11 Selected from any one or more combinations of phenyl, naphthyl, biphenyl, deuterated phenyl, and deuterated naphthyl; R 16 It is selected from any one or more combinations of phenyl, naphthyl, dibenzofuranyl, benzonaphthofuranyl, deuterated phenyl, deuterated biphenyl, deuterated dibenzofuranyl and deuterated benzonaphthofuranyl; R 12 To R 15 and R 17 To R 20 It is selected from hydrogen atoms or deuterium atoms.

10. The organic light-emitting device according to claim 6, characterized in that, The compound represented by general formula I includes at least one of the following compounds:

11. The organic light-emitting device according to claim 6, characterized in that, The compound represented by general formula II includes at least one of the following compounds:

12. The organic light-emitting device according to claim 6, characterized in that, The second host material is selected from at least one of the compounds represented by general formula II.

13. The organic light-emitting device according to claim 1, characterized in that, The material of the first luminescent layer further includes a first guest material, and the material of the second luminescent layer further includes a second guest material; the first guest material and the second guest material are selected from any one of non-thermally activated delayed fluorescence materials, phosphorescent materials and thermally activated delayed fluorescence materials.

14. The organic light-emitting device according to any one of claims 13, characterized in that, The first guest material and the second guest material are selected from non-thermally activated delayed fluorescence materials, and the first guest material and / or the second guest material are selected from at least one of the compounds represented by Formula III: Where X is selected from N, O, S or Se; R 21 To R 25 It is selected from any one or more combinations of hydrogen atom, protium atom, deuterium atom, tritium atom, substituted or unsubstituted aryl group, substituted or unsubstituted heteroaryl group, and substituted or unsubstituted alkyl group.

15. The organic light-emitting device according to claim 14, characterized in that, The first guest material and / or the second guest material are selected from at least one of the following compounds:

16. The organic light-emitting device according to claim 1, characterized in that, The light emitted by the first light-emitting layer and the second light-emitting layer is blue light.

17. The organic light-emitting device according to claim 1, characterized in that, The thickness of the first light-emitting layer is less than or equal to the thickness of the second light-emitting layer.

18. The organic light-emitting device according to claim 17, characterized in that, The thickness of the first light-emitting layer is greater than 0 and less than or equal to 150 angstroms, the thickness of the second light-emitting layer is greater than 0 and less than or equal to 190 angstroms, and the thickness of the electron blocking layer is greater than or equal to 10 angstroms and less than or equal to 150 angstroms.

19. The organic light-emitting device according to any one of claims 1 to 3, characterized in that, The hole mobility of the first host material is less than or equal to the hole mobility of the second host material.

20. A display device, characterized in that, Including the organic light-emitting device as described in any one of claims 1 to 19.

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