Light-emitting device and display apparatus

Abstract

The present disclosure relates to the technical field of display, and provides a light-emitting device and a display apparatus. The light-emitting device of the present disclosure comprises a first electrode, a second electrode, and at least one light-emitting layer arranged between the first electrode and the second electrode; the light-emitting layer comprises a host material, a first dopant material, and a second dopant material which are doped together; the first dopant material is a phosphorescent material, and the second dopant material is a fluorescent material; and the horizontal emission dipole ratio of the first dopant material is between 80% and 100%, and Θ / / =p / / / (p / / +p⟂), wherein Θ / / represents the horizontal emission dipole ratio of the first dopant material, p / / represents the horizontal emission dipole moment of the first dopant material, and p⟂ represents the vertical emission dipole moment of the first dopant material.

Description

Light-emitting device and display device TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of display, and particularly relates to a light-emitting device and a display device. BACKGROUND

[0002] In recent years, with the progress of display technology, people have increasingly high requirements for various performances of display devices. For example, organic light-emitting diodes (OLED) are widely used in the display field due to their lightness, self-luminescence, fast response speed and other characteristics.

[0003] A light-emitting device generally includes an anode, a cathode and a light-emitting layer. The light-emitting principle thereof is that holes generated by the anode and electrons generated by the cathode recombine in the light-emitting layer to form excitons (such as singlet excitons and triplet excitons), so as to emit light through exciton radiative transition.

[0004] However, the light-emitting device is affected by the characteristics of the light-emitting material, and problems such as low internal quantum efficiency (IQE), low device efficiency, low service life, or low color saturation at high brightness may occur, which cannot meet the needs of mass production products, and thus mass production cannot be realized. SUMMARY

[0005] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides a light-emitting device and a display device.

[0006] In a first aspect, a technical solution adopted to solve the technical problems of the present disclosure is a light-emitting device, comprising a first electrode, a second electrode and at least one light-emitting layer arranged between the first electrode and the second electrode.

[0007] The light-emitting layer comprises a host material, a first dopant material and a second dopant material doped together.

[0008] The first dopant material is a phosphorescent material, and the second dopant material is a fluorescent material.

[0009] The horizontal emission dipole ratio of the first dopant material is between 80% and 100%; Θ / / =p∥ / (p∥+p⊥), wherein Θ / / represents the horizontal emission dipole ratio of the first dopant material, p∥represents the horizontal emission dipole moment of the first dopant material, and p⊥represents the vertical emission dipole moment of the first dopant material.

[0010] In some embodiments, the first dopant material is an iridium complex, and the iridium complex is composed of a main ligand, an auxiliary ligand and an iridium ion; wherein the main ligand at least comprises a phenyl group and a phenyl derivative.

[0011] In some embodiments, the iridium complex has the following general structure (I):

[0012] wherein, represents a main ligand, represents an ancillary ligand;

[0013] wherein, L1-L3 in the general structure (I) are each independently selected from a substituted or unsubstituted C5-C30 carbocyclic group, and a substituted or unsubstituted C1-C30 heterocyclic group, or L1-L3 are each independently selected from an unsubstituted or at least one Q-substituted cyclopentadienyl group, a cyclohexane group, a cyclohexene group, a phenyl group, a naphthyl group, an anthracene group, a phenanthrene group, a benzo[9,10]phenanthrene group, a pyrene group, a group, a furan group, a thiophene group, a silole group, an indene group, a fluorene group, an indole group, a carbazole group, a benzofuran group, a dibenzofuran group, a benzothiophene group, a dibenzothiophene group, a benzothiophene group, a dibenzothiophene group, a diazine group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, a dioxazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzodioxole group, and a benzothiadiaole group; wherein Q is any one of deuterium, -F, -CD3, -CD2H, -CDH2, -CF3, -CF2H, -CFH2, cyano, nitro, C1-C10 alkyl, C1-C10 alkoxy, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, norbornane, norbornene, cyclopentenyl, cyclohexenyl, cycloheptenyl, phenyl, naphthyl, pyridyl, pyrimidyl, dibenzofuranyl, dibenzothiophenyl;

[0014] m1-m3 are each independently selected from any integer from 0-5;

[0015] n1-n3 are each independently selected from any integer from 0-5;

[0016] R1-R8 are each independently selected from any one or combination of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino;

[0017] X, X1-X6are each independently selected from any one of BR, NR, PR, oxygen, sulfur, selenium, carbonyl, acyl, dioxysulfur, CRR', SiRR', GeRR'; wherein R and R' in BR, NR, PR, CRR', SiRR', GeRR' are each independently selected from any one or more of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl, phosphinyl; B in BR represents a boron atom; N in NR represents a nitrogen atom; P in PR represents a phosphorus atom; C in CRR' represents a carbon atom; Si in SiRR' represents a silicon atom; Ge in GeRR' represents a germanium atom.

[0018] In some embodiments, any adjacent substituents on the same ring group in structural formula (I) are joined or fused to form a ring.

[0019] In some embodiments, the iridium complex comprises any one of the following structures:

[0020] In some embodiments, in the light-emitting stage, the triplet excitons formed by the host material and the triplet excitons formed by the first dopant material are both transferred to the singlet state light emission of the second dopant material by fluorescence resonance energy transfer.

[0021] In some embodiments, the doping concentration of the host material is between 83% and 94.5%; the doping concentration of the host material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material, and the second dopant material;

[0022] The doping concentration of the first dopant material is between 15% and 5%; the doping concentration of the first dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material, and the second dopant material;

[0023] The doping concentration of the second dopant material is between 2% and 0.5%; the doping concentration of the second dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material, and the second dopant material.

[0024] In some embodiments, the ratio of the spectral overlap area between the photoluminescence spectrum of the first dopant material and the absorption spectrum of the second dopant material to the area of the absorption spectrum of the second dopant material is greater than 50%.

[0025] In some embodiments, the structural formula (II) of the second dopant material is as follows:

[0026] wherein ring CY is a C5-C30 monocyclic or fused ring group, or each independently a C5-C30 monoheterocyclic or fused heterocyclic group, wherein the heteroatom is one or more of nitrogen, oxygen, sulfur; R 26 ~R 30 each independently represents one or more combinations of hydrogen, deuterium, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group; n represents an integer greater than or equal to 1.

[0027] In some embodiments, the second dopant material has a molecular structure of

[0028] In some embodiments, E T1 (Host) > E T1 (Dopant1) > E S1 (Dopant2); wherein E T1 (Host) represents the lowest triplet excited energy of the host material, E T1 (Dopant1) represents the lowest triplet excited energy of the first dopant material, E T1 (Dopant2) represents the lowest triplet excited energy of the second dopant material.

[0029] E S1 (Host) ≥ E S1 (Dopant1) > E S1 (Dopant2); wherein E S1 (Host) represents the lowest singlet excited energy of the host material, E S1 (Dopant1) the lowest singlet excited energy of the first dopant material, the lowest singlet excited energy of the second dopant material.

[0030] In some embodiments, the host material comprises a first host material and a second host material.

[0031] The first host material is a hole-transporting host material; the second host material is an electron-transporting host material.

[0032] In some embodiments, the ratio of the mass of the first host material to the mass of the second host material is between 1:9 to 5:5; or, the ratio of the mass of the second host material to the mass of the first host material is between 1:9 to 5:5.

[0033] In some embodiments, the light-emitting device further comprises a hole transport layer disposed on the side of the first electrode close to the light-emitting layer, and an electron transport layer disposed on the side of the second electrode close to the light-emitting layer.

[0034] In some embodiments, the light-emitting layer comprises a first light-emitting layer and a second light-emitting layer; the first light-emitting layer is closer to the first electrode than the second light-emitting layer.

[0035] The light-emitting device further comprises a first hole transport layer disposed on the side of the first electrode close to the first light-emitting layer, an N-type doped charge generation layer and a P-type doped charge generation layer disposed on the side of the first light-emitting layer close to the second light-emitting layer, and an electron transport layer disposed on the side of the second electrode close to the second light-emitting layer.

[0036] In some embodiments, the light-emitting device is a green light-emitting device.

[0037] In the second aspect, the embodiments of the present disclosure further provide a display device comprising the light-emitting device according to any one of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0038] FIG. 1 is an energy interaction diagram of a light-emitting device according to an embodiment of the present disclosure;

[0039] FIG. 2 is a schematic diagram of the film layers of a light-emitting device according to an embodiment of the present disclosure;

[0040] FIG. 3 is a schematic diagram of horizontal emission dipoles and vertical emission dipoles according to an embodiment of the present disclosure;

[0041] FIG. 4 is a schematic diagram of the normalized electroluminescence spectrum of an iridium complex Ir-1 pure film and the normalized absorption spectrum of a fluorescent guest material GD-1 pure film according to an embodiment of the present disclosure;

[0042] FIG. 5 is a schematic diagram of the device film layers of a single-layer light-emitting layer according to an embodiment of the present disclosure;

[0043] FIG. 6 is a schematic diagram of the electroluminescence spectrum measured for the device corresponding to Example 2 in Table 3 according to an embodiment of the present disclosure;

[0044] FIGS. 7a and 7b respectively show the viewing angle characteristics of Example 4 in Table 3 according to an embodiment of the present disclosure;

[0045] FIG. 8 is a schematic diagram of the film layers of a tandem light-emitting device according to an embodiment of the present disclosure;

[0046] FIG. 9 is a schematic diagram of the electroluminescence spectrum measured for the device corresponding to Example 5 in Table 5 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the following will be combined with the accompanying drawings to make a clear and complete description of the technical solutions of the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. The components of the embodiments of the present disclosure generally described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the accompanying drawings is not intended to limit the scope of the claimed present disclosure, but only represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present disclosure.

[0048] Unless otherwise defined, technical or scientific terms used in the present disclosure should be understood as having the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are used to distinguish different components. Similarly, the terms "one", "a" or "the" and similar terms do not denote quantity limitation, but mean that there is at least one. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships may also be changed accordingly.

[0049] In the present disclosure, "a plurality of or several" refers to two or more. The term "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent three cases: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0050] In the related art, light-emitting devices can be divided into phosphorescent light-emitting devices and fluorescent light-emitting devices according to different light-emitting modes, and the main difference between the two is whether the guest material (i.e., the doping material different from the host material) of the light-emitting layer is a phosphorescent material or a fluorescent material. Among them, the traditional fluorescent material has a narrow spectrum and high stability, but the intersystem crossing (ISC) between the triplet state and the singlet state in the traditional fluorescent material is forbidden, so the triplet exciton cannot return to the ground state to emit light, and only the singlet exciton can emit light, so the internal quantum efficiency (IQE) can only theoretically reach 25%. The phosphorescent material can make both the triplet exciton and the singlet exciton return to the ground state and emit light, so the theoretical IQE can reach 100%. However, when the metal complex phosphorescent material is directly used as the light-emitting center, it is easy to promote the formation of adducts and charge traps, resulting in poor device stability, and thus damaging the device lifetime and efficiency. In addition, the microsecond-level triplet exciton of the phosphorescent material is easy to cause triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA), which will accelerate the degradation of the device, and the color saturation is low at high brightness.

[0051] In view of this, the present disclosure provides a light-emitting device, and the light-emitting layer of the light-emitting device is composed of a host material, a first doping material and a second doping material. Among them, the first doping material belongs to a phosphorescent material, and the second doping material belongs to a fluorescent material. As shown in FIG. 1, during the light-emitting stage, under the action of an electric field, carriers are injected through the electrodes and then transported to the light-emitting layer by the carrier transport layer, forming singlet excitons and triplet excitons on the host material, and transferring energy to the first doping material through fluorescence resonance energy transfer (FRET) and Dexter excitation transfer (DET) mode. The horizontal emission dipole ratio Θ / / of the first doping material is between 80% and 100%. The higher the dipole strength, the more conducive to FRET energy transfer from the triplet exciton generated by the first doping material to the singlet state of the second doping material, and the singlet exciton quickly radiative decay to emit light, thereby improving the light-emitting efficiency of the light-emitting device. Resonance Energy Transfer,FRET) and Dexter Excitation Transfer (DET) mode. The horizontal emission dipole ratio Θ / / of the first doping material is between 80% and 100%. The higher the dipole strength, the more conducive to FRET energy transfer from the triplet exciton generated by the first doping material to the singlet state of the second doping material, and the singlet exciton quickly radiative decay to emit light, thereby improving the light-emitting efficiency of the light-emitting device.

[0052] FIG. 2 is a schematic diagram of a film layer of a light-emitting device provided by the present disclosure. As shown in FIG. 2, the light-emitting device includes a first electrode 10, a second electrode 20, and at least one light-emitting layer EML disposed between the first electrode 10 and the second electrode 20. For example, if the light-emitting device is a tandem light-emitting device, the tandem light-emitting device includes at least two light-emitting layers EML.

[0053] The light-emitting layer EML includes a host material, a first dopant material and a second dopant material doped together. The first dopant material is a phosphorescent material, and the second dopant material is a fluorescent material. Optionally, the first dopant material is a phosphorescent sensitizer material. The second dopant material is a conventional fluorescent material or a new type of thermally activated delayed fluorescence (TADF) material. The second dopant material serves as a light-emitting material in the embodiments of the present disclosure. It should be noted that the thermally activated delayed fluorescence (TADF) material allows the conversion of non-radiative triplet excited states to radiative singlet states through reverse intersystem crossing (RISC).

[0054] FIG. 3 is a schematic diagram of horizontal emission dipole and vertical emission dipole provided by the embodiments of the present disclosure. As shown in FIG. 3, the horizontal emission dipole ratio of the first dopant material is between 80% and 100%; Θ / / = p∥ / (p∥+p⊥), where Θ / / represents the horizontal emission dipole ratio of the first dopant material, p∥ represents the horizontal emission dipole moment of the first dopant material, and p⊥ represents the vertical emission dipole moment of the first dopant material.

[0055] It should be noted that the higher the horizontal emission dipole ratio, the higher the degree of horizontal dipole orientation of the material, which is more conducive to FRET energy transfer from triplet excitons to the singlet state of the acceptor. The horizontal emission dipole ratio Θ / / of the first dopant material doped in the embodiments of the present disclosure is between 80% and 100%, and the degree of horizontal dipole orientation is very high, which is conducive to FRET energy transfer from triplet excitons generated by the first dopant material to the singlet state of the second dopant material, and the singlet exciton quickly radiates and decays to emit light, thereby improving the light-emitting efficiency of the light-emitting device.

[0056] Exemplarily, the light-emitting device is an OLED device.

[0057] In some embodiments, the first dopant material provided by the embodiments of the present disclosure, although belonging to the category of phosphorescent materials, is different from conventional phosphorescent materials, specifically: the first dopant material is an iridium complex, and the iridium complex is composed of a main ligand, an auxiliary ligand and an iridium ion; wherein the main ligand includes at least a phenyl group and a phenyl derivative. Exemplarily, the iridium ion can be a trivalent iridium ion.

[0058] The arrangement of the auxiliary ligand does not affect the horizontal emission dipole ratio Θ / / of the first dopant material. The phenyl derivative is used to modify the original host ligand structure (which can be understood as the host ligand in the traditional metal complex phosphorescent material) to form the host ligand of the present disclosure. The host ligand modified by the phenyl derivative increases the π-π interaction between the iridium complex and the host material, which is conducive to the C2 axis of the iridium complex being perpendicular to the substrate and the transition dipole moment (TDM) being perpendicular to the C2 axis, thereby improving the horizontal emission dipole orientation degree (i.e. the horizontal emission dipole ratio Θ / / ), which is conducive to the triplet excitons generated by the iridium complex transferring energy to the singlet state of the second dopant material through FRET, and the singlet excitons rapidly radiate to emit light, thereby improving the luminous efficiency of the light-emitting device.

[0059] In some embodiments, the general structure of the iridium complex is as follows:

[0060] The general structure (I) is as follows: represents the host ligand, represents the auxiliary ligand.

[0061] The host ligand is modified by the phenyl derivative to improve the horizontal dipole ratio. Wherein “~” represents the connection position of the phenyl derivative.

[0062] wherein L1to L3in structural formula (I) are each independently selected from a substituted or unsubstituted C5to C30carbocyclic group, and a substituted or unsubstituted C1to C30heterocyclic group, or L1to L3are each independently selected from an unsubstituted or at least one Q-substituted cyclopentadiene group, cyclohexane group, cyclohexene group, phenyl group, naphthyl group, anthracene group, phenanthrene group, benzo[9,10]phenanthrene group, pyrene group, group, furan group, thiophene group, silole group, indene group, fluorene group, indole group, carbazole group, benzofuran group, dibenzofuran group, benzothiophene group, dibenzothiophene group, benzothiophene group, dibenzothiophene group, azaf uorene group, azacarbazole group, azadibenzofuran group, azadibenzothiophene group, azadibenzothiophene group, pyridine group, pyrimidine group, pyrazine group, pyridazine group, triazine group, quinoline group, isoquinoline group, quinoxaline group, quinazoline group, phenanthroline group, pyrrole group, pyrazole group, imidazole group, triazole group, oxazole group, isoxazole group, thiazole group, isothiazole group, dioxazole group, thiadiazole group, benzopyrazole group, benzimidazole group, benzoxazole group, benzothiazole group, benzodioxazole group, and benzothiadiazoie group; wherein Q is any one of deuterium, -F, -CD3, -CD2H, -CDH2, -CF3, -CF2H, -CFH2, cyano, nitro, C1to C10alkyl, C1to C10alkoxy, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, norbornane group, norbornene group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, phenyl group, naphthyl group, pyridyl group, pyrimidyl group, dibenzofuranyl group, dibenzothiophenyl group.

[0063] wherein m1to m3are each independently selected from any integer of 0 to 5.

[0064] wherein n1to n3are each independently selected from any integer of 0 to 5.

[0065] wherein R1to R8are each independently selected from any one or a combination of more than one of hydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino.

[0066] wherein X, X1-X6 are each independently selected from any one of BR, NR, PR, oxygen (O), sulfur (S), selenium (Se), carbonyl (C=O), acyl (S=O), sulfur dioxide (SO2), CRR', SiRR', GeRR'; wherein R and R' in BR, NR, PR, CRR', SiRR', GeRR' are each independently selected from any one or combination of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl, phosphinyl. It is noted that "B" in "BR" represents a boron atom; "N" in "NR" represents a nitrogen atom; "P" in "PR" represents a phosphorus atom; "C" in CRR' represents a carbon atom; "Si" in SiRR' represents a silicon atom; "Ge" in GeRR' represents a germanium atom.

[0067] wherein N represents a nitrogen atom.

[0068] In some embodiments, any adjacent substituents on the same ring group in structural formula (I) are joined or fused to form a ring.

[0069] In some embodiments, the iridium complex comprises any one of the following structures:

[0070] It is noted that the degree of horizontal emission dipole orientation can be represented by the horizontal emission dipole ratio Θ / / .

[0071] The iridium complex with a doping concentration of 10% is doped in the host material to make the light-emitting layer EML, and the horizontal emission dipole ratio Θ / / is obtained by angle-resolved spectroscopy, and the quantum yield (PLQY) is measured by a steady-state-transient spectrometer with an integrating sphere, as shown in Table 1.

[0072] Table 1

[0073] wherein Ir-ref.1-Ir-ref.3 are existing sensitizer materials containing iridium atoms.

[0074] As can be seen from Table 1, the iridium complex designed in the present disclosure has a higher degree of horizontal emission dipole orientation, and at the same time, has a higher quantum yield (PLQY).

[0075] In some embodiments, as shown in FIG. 1, due to the second dopant material, the triplet excitons formed by the host material and the triplet excitons formed by the first dopant material are both transferred to the singlet state light emission of the second dopant material through FRET during the light-emitting stage, and the FRET is enhanced; at the same time, due to the enhancement of the FRET, the DET of the host material and the first dopant material to the second dopant material is inhibited, and thus the case of the second dopant material directly capturing carriers to emit light is also inhibited. Therefore, the host material and the first dopant material of the present disclosure are basically transferred to the singlet state of the second dopant material through FRET, and the singlet state rapidly radiative decays to emit light.

[0076] In some embodiments, the doping concentration of the host material is between 83% and 94.5%; the doping concentration of the host material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material; the doping concentration of the first dopant material is between 15% and 5%; the doping concentration of the first dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material; the doping concentration of the second dopant material is between 2% and 0.5%; the doping concentration of the second dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material.

[0077] Optionally, the doping concentration of the host material is 89%, the doping concentration of the first dopant material is 10%, and the doping concentration of the second dopant material is 1%.

[0078] Compared with the doping concentrations of the host material and the first dopant material, the present embodiment only dopes a small amount of the second dopant material (light-emitting material). Due to the doping of only a small amount of the second dopant material (light-emitting material), the FRET of the first dopant material to the second dopant material is enhanced, the DET of the host material and the first dopant material to the second dopant material is inhibited, and thus the case of the second dopant material directly capturing carriers to emit light is also inhibited. Therefore, the host material and the first dopant material of the present disclosure are basically transferred to the singlet state of the second dopant material through FRET, and the singlet state rapidly radiative decays to emit light.

[0079] In some embodiments, the second dopant material can contain boron atoms or can not contain boron atoms.

[0080] The structural general formula (two) of the second dopant material containing boron atoms is as follows:

[0081] wherein the ring CY is a monocyclic group or a fused ring group with C5-C30, or each independently is a monoheterocyclic group or a fused heterocyclic group with C5-C30, wherein the heteroatom is one or more of nitrogen, oxygen and sulfur; R 26 ~R30 each independently represents one or more combinations of hydrogen, deuterium, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group; n represents an integer greater than or equal to 1;

[0082] wherein, B represents a boron atom; N represents a nitrogen atom.

[0083] For example, the second dopant material containing a boron atom includes, but is not limited to, any one of the following structures:

[0084] For example, the first dopant material is selected as iridium complex Ir-1, and the second dopant material is selected as fluorescent guest material GD-1. FIG. 4 is a schematic diagram of the normalized electroluminescence spectrum of the iridium complex Ir-1 pure film and the normalized absorption spectrum of the fluorescent guest material GD-1 pure film provided by the embodiment of the present disclosure, as shown in FIG. 4, wherein 41 represents the normalized electroluminescence spectrum of the iridium complex Ir-1 pure film, and 42 represents the normalized absorption spectrum of the fluorescent guest material GD-1 pure film. Wherein, the abscissa represents the wavelength Wavelength (unit: nanometer nm) of visible light, and the ordinate represents the spectral intensity Intensity. As shown in FIG. 4, the normalized electroluminescence spectrum of the iridium complex Ir-1 pure film and the normalized absorption spectrum of the fluorescent guest material GD-1 pure film overlap, and the spectral overlap area between the photoluminescence spectrum of the first dopant material and the absorption spectrum of the second dopant material is greater than 50% of the area of the absorption spectrum of the second dopant material. It should be noted that the higher the overlap area of the electroluminescence spectrum of the donor and the absorption spectrum of the acceptor, the more conducive to FRET energy transfer, thereby facilitating the improvement of the efficiency of the light-emitting device, and facilitating the stability of the device.

[0085] For example, the second dopant material not containing a boron atom can be: wherein, N represents a nitrogen atom; O represents an oxygen atom, and S represents a sulfur atom.

[0086] In some embodiments, as shown in FIG. 1, E T1 (Host) > E T1 (Dopant1) > E S1 (Dopant2); wherein, E T1 (Host) represents the lowest triplet excited energy of the host material, E T1 (Dopant1) represents the lowest triplet excited energy of the first dopant material, E T1(Dopant2) represents the lowest triplet excited energy of the second dopant material; E S1 (Host) ≥ E S1 (Dopant1) > E S1 (Dopant2); wherein, E S1 (Host) represents the lowest singlet excited energy of the host material, E S1 (Dopant1) represents the lowest singlet excited energy of the first dopant material, and E

[0087] In some embodiments, the thickness of the light-emitting layer EML is between 10 nm and 100 nm.

[0088] In some embodiments, the glass transition temperature Tg of the host material is ≥ 100℃. It should be noted that the glass transition temperature (Tg) refers to the temperature at which the material changes from a glass state to a high-elasticity state during heating. The glass transition temperature is an important physical property of amorphous polymer materials, and this temperature range marks the lowest temperature at which the internal polymer chain segments begin to move. Below the glass transition temperature, the material behaves as a rigid solid with little deformation; above the glass transition temperature, the material deforms significantly and exhibits higher elasticity. The glass transition temperature directly affects the use performance and process performance of the material, such as mechanical strength, thermal stability, and chemical resistance. The glass transition temperature Tg of the present disclosure is ≥ 100℃, which has higher thermal stability and chemical resistance.

[0089] In some embodiments, the host material includes a first host material and a second host material; the first host material is a hole-transporting host material, thereby facilitating hole transport; and the second host material is an electron-transporting host material, thereby facilitating electron transport.

[0090] wherein the structure general formula (three) of the hole-transporting host material is as follows:

[0091] wherein R1-R8 are each independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted C2-C30 heteroaryl. L1 and L2 are each independently selected from the group consisting of a single bond, a substituted or unsubstituted C6-C30 arylene, a substituted or unsubstituted C2-C30 heteroarylene. Ar1 and Ar2 are each independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C3 to C30 cycloalkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted carbazolyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted dibenzothiophenyl, a substituted or unsubstituted C6-C30 arylamine, a substituted or unsubstituted C1-C30 alkoxy, a substituted or unsubstituted C3-C40 silyl, a substituted or unsubstituted C1-C30 alkylthiol, a substituted or unsubstituted C6-C30 arylthiol, a halogen, a halogen-containing group, a cyano group, a hydroxyl group, an amino group, a nitro group.

[0092] For example, “-L1-Ar1” and “-L2-Ar2” can be as follows:

[0093] For example, the hole-transporting host material includes, but is not limited to, any one of the following:

[0094] wherein the structure general formula (four) of the electron-transporting host material is as follows:

[0095] wherein R9-R 13 are each independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted C1-C30 alkyl, a substituted or unsubstituted C6-C30 aryl, a substituted or unsubstituted C2-C30 heteroaryl.

[0096] Ar3 is selected from structure A or structure B. Wherein structure A: structure B: wherein “~” represents the position of the structure connected to the structure general formula (four). X is independently selected from any one of oxygen (O), sulfur (S), NR, CR2, SiR2, GeR2. Wherein R 14 R 25 , R is independently selected from the group consisting of hydrogen, deuterium, a substituted or unsubstituted C1-C20 alkyl, a substituted or unsubstituted C6-C50 aryl, a substituted or unsubstituted C2-C50 heteroaryl. 14 R25 The two adjacent ones can also form a ring, and the ring can be further modified by Q. Q is selected from any one or a combination of more than one of hydrogen, deuterium, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6 to C50 aryl group, and a substituted or unsubstituted C2-C50 heteroaryl group.

[0097] Exemplarily, the electron-transporting host material includes, but is not limited to, any one of the following:

[0098] In some embodiments, the ratio of the mass of the first host material to the mass of the second host material is between 1:9 and 5:5; or, the ratio of the mass of the second host material to the mass of the first host material is between 1:9 and 5:5.

[0099] Exemplarily, the first host material is selected from a hole-transporting host material, and the second host material is selected from an electron-transporting host material. The ratio of the mass of the first host material to the mass of the second host material is between 1:9 and 5:5, and in the case that 5:5 is not included, the hole-transporting ability of the host material is greater than the electron-transporting ability, so that the carrier transport region, the exciton recombination center and the light-emitting center are effectively separated, and the device is more stable.

[0100] Exemplarily, the first host material is selected from a hole-transporting host material, and the second host material is selected from an electron-transporting host material. The ratio of the mass of the second host material to the mass of the first host material is between 1:9 and 5:5, and in the case that 5:5 is not included, the electron-transporting ability of the host material is greater than the hole-transporting ability, so that the carrier transport region, the exciton recombination center and the light-emitting center are effectively separated, and the device is more stable.

[0101] Exemplarily, the doping concentration of the host material is 89%, the doping concentration of the first dopant material is 10%, and the doping concentration of the second dopant material is 1%. In this doping ratio, the obtained light-emitting layer EML is compared with the comparative example as shown in Table 2 below.

[0102] Table 2

[0103] In the table, P-1(60):N-1(40) represents the mass ratio of the first host material to the second host material is 6:4. λ (nm) represents the light-emitting wavelength of the light-emitting layer EML, i.e., green light. τ (μs) represents the lifetime of the triplet exciton.

[0104] As shown in Table 2, the triplet exciton lifetime of the light-emitting layer EML formed by Comparative Examples 1-5 is relatively long, and the triplet exciton lifetime of the light-emitting layer EML formed by Examples 1-6 of the present disclosure is relatively short, which indicates that the first dopant material (iridium complex) and the second dopant material (fluorescent material) designed in the present disclosure have high FRET efficiency. The shorter triplet exciton lifetime indicates that the host material and the first dopant material are basically transferred to the singlet state of the second dopant material through FRET, and the singlet state is quickly radiative decayed to emit light, thereby improving the light-emitting efficiency of the device.

[0105] In some embodiments, FIG. 5 is a schematic diagram of a device film layer of a single-layer light-emitting layer provided by the present disclosure. As shown in FIG. 5, the light-emitting device further comprises a hole injection layer HIL, a hole transport layer HTL and an electron blocking layer HBL arranged in sequence on the side of the first electrode 10 close to the light-emitting layer EML, and an electron injection layer EIL, an electron transport layer ETL and a hole blocking layer HBL arranged in sequence on the side of the second electrode 20 close to the light-emitting layer EML.

[0106] The first electrode 10 is an anode Anode of the light-emitting device. For example, the material of the anode Anode can be selected from high work function electrode materials. In the case of a bottom-emitting device, the anode Anode can be selected from, but is not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO) and the like. The thickness of the anode Anode is between 80 nm and 200 nm. In the case of a top-emitting device, the anode Anode can be selected from, but is not limited to, Ag / ITO, Ag / IZO, Ag / SnO2, Ag / ZnO, Al / ITO, Al / IZO and the like. At this time, the thickness of the metal layer (Ag or Al) is between 80 nm and 100 nm, and the thickness of the oxide layer (ITO, IZO, SnO2 or ZnO) is between 5 nm and 20 nm. The average reflectivity of the anode Anode in the visible region is between 85% and 95%.

[0107] The hole injection layer HIL is mainly used to reduce the hole injection barrier and improve the hole injection efficiency. For example, the material of the hole injection layer HIL can be selected from, but is not limited to, HATCN, MnO3, CuPc and the like. Alternatively, the material of the hole injection layer HIL can also be p-doped in the hole transport material, such as NPB:F4TCNQ, TAPC:MnO3 and the like. The thickness of the hole injection layer HIL is between 5 nm and 20 nm, and the p-doping concentration is between 0.5% and 10%. Here, the so-called “p-doping concentration” can be understood as the ratio of the p-doping mass to the sum of the p-doping mass and the mass of the hole transport material.

[0108] The hole transport layer HTL is mainly used for transporting holes generated by the anode. The hole transport layer HTL can be prepared by using a carbazole material with high hole mobility in the process preparation stage. The highest occupied molecular orbital (HOMO) energy level of the material of the hole transport layer HTL is between -5.2 eV and -5.6 eV. The thickness of the hole transport layer HTL is between 80 nm and 140 nm.

[0109] The electron blocking layer HBL is mainly used for blocking electrons and excitons generated in the light-emitting layer EML, and transporting holes. The lowest triplet energy (T1) of the material of the electron blocking layer HBL is greater than the lowest triplet energy (T1) of the iridium (III) complex in the light-emitting layer EML, and the difference is greater than or equal to 0.2 eV, that is, T1(EBL)-T1(Host)≥0.2 eV. The highest occupied molecular orbital (HOMO) energy level of the material of the electron blocking layer HBL is deeper than the highest occupied molecular orbital (HOMO) energy level of the host material in the light-emitting layer EML, and the difference is less than or equal to 0.2 eV, that is, |HOMO(EBL)-HOMO(Host)|≤0.2 eV. The thickness of the electron blocking layer HBL is between 1 nm and 10 nm.

[0110] The specific structure, material and parameter of the light-emitting layer EML shown in FIG. 5 are limited, and refer to the detailed description of the light-emitting layer EML above, and the repeated parts will not be described herein.

[0111] The hole blocking layer HBL is mainly used for blocking holes and excitons generated in the light-emitting layer EML, and transporting electrons. The lowest triplet energy (T1) of the material of the hole blocking layer HBL is greater than the lowest triplet energy (T1) of the iridium (III) complex in the light-emitting layer EML, that is, T1(HBL)>T1(Host). The lowest unoccupied molecular orbital (LUMO) energy level of the material of the hole blocking layer HBL is shallower than the lowest unoccupied molecular orbital (LUMO) energy level of the host material in the light-emitting layer EML, and the difference is less than or equal to 0.4 eV, that is, |LUMO(HBL)-LUMO(Host)|≤0.4 eV. The thickness of the hole blocking layer HBL is between 1 nm and 10 nm.

[0112] The electron transport layer ETL is mainly used for transporting electrons. The material of the electron transport layer ETL includes an electron transport material and Liq doped together, and the doping mass ratio of the two is 10:1 to 1:1. The thickness of the electron transport layer ETL is between 20 nm and 70 nm. Liq can be selected from the following materials The group of the electron transport material contains at least one

[0113] The electron injection layer EIL is mainly used to reduce the electron injection barrier and improve the electron injection efficiency. Exemplarily, the material of the electron injection layer EIL can be selected from, but not limited to, one or more combinations of Yb, Li, LiF, NaCl, CsF, Li2O, BaO, Liq, etc. The thickness of the electron injection layer EIL is between 0.5 nm and 2 nm.

[0114] The second electrode 20 is a cathode of the light-emitting device. Exemplarily, the cathode can be selected from low work function electrode materials. For example, the material of the cathode can be selected from, but not limited to, Mg, Ag, Al, Al-Li, Ca, Mg:In, Mg:Ag, etc. In the case that the light-emitting device is a bottom-emitting device, the thickness of the cathode is between 80 nm and 100 nm. In the case that the light-emitting device is a top-emitting device, the thickness of the cathode is between 10 nm and 20 nm, and can be prepared by using an alloy such as Mg:Ag, and the mass adjustment ratio of Mg:Ag is between 3:7 and 1:9.

[0115] Exemplarily, in the case that the light-emitting device is a top-emitting device, as shown in FIG. 5, the light-emitting device further comprises a light extraction layer CPL arranged on the side of the cathode away from the light-emitting layer EML. The light extraction layer CPL covers the cathode, and is mainly used to improve the light extraction efficiency and protect the cathode. The thickness of the light extraction layer CPL is between 50 nm and 100 nm, and preferably the refractive index of the material of the light extraction layer CPL at a wavelength of 530 nm is greater than 1.9, so as to transmit more light.

[0116] Exemplarily, the light-emitting device further comprises an encapsulation layer arranged on the side of the light extraction layer CPL away from the cathode. The encapsulation layer can be packaged by using a frame glue, or can be packaged by using a film.

[0117] Exemplarily, the structure of a single-layer light-emitting layer EML light-emitting device comprises: ITO / Ag / ITO (150 nm)→HIL (10 nm)→HTL_1 (100 nm)→HTL_2 (25 nm)→EBL (5 nm)→EML (40 nm)→HBL (5 nm)→ETL (30 nm)→EIL (1.5 nm)→Mg:Ag (16.5 nm)→CPL (700 nm). The structure of the light-emitting layer EML comprises the following examples.

[0118] Comparative Example 1: P-1 (60): N-1 (40): Ir-ref.1: GD-1 (89%:10%:1%).

[0119] Comparative Example 2: P-1 (60): N-1 (40): Ir-ref. 2: GD-1 (89%: 10%: 1%).

[0120] Comparative Example 3: P-1 (60): N-1 (40): Ir-ref. 3: GD-1 (89%: 10%: 1%).

[0121] Comparative Example 4: P-1 (50): N-1 (50): Ir-ref. 1: GD-1 (89%: 10%: 1%).

[0122] Comparative Example 5: P-1 (40): N-1 (60): Ir-ref. 2: GD-1 (89%: 10%: 1%).

[0123] Comparative Example 6: P-2 (60): N-3 (40): Ir-ref. 3: GD-2 (89%: 10%: 1%).

[0124] Comparative Example 7: P-3 (60): N-2 (40): Ir-ref. 1: GD-3 (89.2%: 10%: 0.8%).

[0125] Comparative Example 8: P-3 (60): N-3 (40): Ir-ref. 1: GD-2 (88%: 12%: 1%).

[0126] Example 1: P-1 (60): N-1 (40): Ir-1: GD-1 (89%: 10%: 1%).

[0127] Example 2: P-1 (60): N-1 (40): Ir-2: GD-1 (89%: 10%: 1%).

[0128] Example 3: P-1 (60): N-1 (40): Ir-3: GD-1 (89%: 10%: 1%).

[0129] Example 4: P-1 (50): N-1 (50): Ir-1: GD-1 (89%: 10%: 1%).

[0130] Example 5: P-1 (40): N-1 (60): Ir-2: GD-1 (89%: 10%: 1%).

[0131] Example 6: P-2 (60): N-3 (40): Ir-3: GD-2 (89%: 10%: 1%).

[0132] Example 7: P-3 (60): N-2 (40): Ir-1: GD-3 (89.2%: 10%: 0.8%).

[0133] Example 8: P-3 (60): N-3 (40): Ir-1 : GD-2 (88%: 12%: 1%).

[0134] Example 9: P-1 (60): N-1 (40): Ir-1 : GD-4 (89%: 10%: 1%).

[0135] Example 10: P-1 (60): N-1 (40): Ir-2: GD-5 (89%: 10%: 1%).

[0136] Example 11 : P-1 (60): N-1 (40): Ir-3: GD-6 (89%: 10%: 1%).

[0137] Example 12: P-1 (60): N-1 (40): Ir-1 : GD-7 (89%: 10%: 1%).

[0138] Example 13: P-1 (60): N-1 (40): Ir-2: GD-8 (89%: 10%: 1%).

[0139] Example 14: P-1 (60): N-1 (40): Ir-3: GD-9 (89%: 10%: 1%).

[0140] Example 15: P-1 (60): N-1 (40): Ir-1 : GD-10 (89%: 10%: 1%).

[0141] Example 16: P-1 (60): N-1 (40): Ir-2: GD-11 (89%: 10%: 1%).

[0142] The above, Examples 1-8 and Comparative Examples 1-8 differ only in the first dopant material. The first dopant material of the present disclosure is selected from Ir-1, Ir-2 or Ir-3; the first dopant material of the comparative examples is selected from Ir-ref.1, Ir-ref.2 or Ir-ref.3.

[0143] Each of the above examples (i.e. Comparative Examples 1-8, Examples 1-16) was subjected to device testing. The testing conditions included obtaining the device emission wavelength (λ), voltage (V) at 15 mA / cm 2 (current density), current efficiency (CE) using IVL testing equipment. Also, the device lifetime was obtained using a lifetime testing equipment, which measures the time (LT 2 ) in hours for the device luminance to decay from the initial value to 95% at 1000 cd / m 95 , the specific values are shown in Table 3 below.

[0144] Table 3

[0145] As shown in Table 3, the iridium complexes obtained by modifying the main ligand with phenyl or phenyl derivatives have high dipole orientation of horizontal emission, and the corresponding phosphorescent sensitized fluorescent organic light-emitting diode devices have more excellent performance.

[0146] For example, FIG. 6 is a schematic diagram of the electroluminescence spectrum of the device corresponding to Example 2 in Table 3, as shown in FIG. 6, wherein the abscissa represents the wavelength of visible light Wavelength (unit: nanometer nm), and the ordinate represents the spectral intensity of the normalized electroluminescence spectrum Intensity. As can be seen, the electroluminescence spectrum of the light-emitting device is narrow and has higher stability.

[0147] For example, FIGS. 7a and 7b are schematic diagrams of the viewing angle characteristics of Example 4 in Table 3, respectively. As shown in FIG. 7a, the abscissa represents the deflection angle, and the ordinate represents the luminance decay value. As shown in FIG. 7b, the abscissa represents the deflection angle, and the ordinate represents the change of color coordinates. Curve 71 represents the viewing angle characteristics of the color corresponding to the color coordinates (0.134, 0.760), curve 72 represents the viewing angle characteristics of the color corresponding to the color coordinates (0.146, 0.761), curve 73 represents the viewing angle characteristics of the color corresponding to the color coordinates (0.165, 0.762), and curve 74 represents the viewing angle characteristics of the color corresponding to the color coordinates (0.191, 0.751). The specific parameters are shown in Table 4.

[0148] Table 4

[0149] In the color coordinates, the distance value between the two points of “measured color” and “accurate color” is the value of JNCD of the screen. L-decay represents luminance decay.

[0150] As shown in Table 4, the viewing angle color deviation and luminance of the light-emitting device when emitting deep green light are good.

[0151] In some embodiments, FIG. 8 is a schematic diagram of a film layer of a light-emitting device according to an embodiment of the present disclosure. As shown in FIG. 8, the light-emitting layer EML includes a first light-emitting layer EML1 and a second light-emitting layer EML2; the first light-emitting layer EML1 is closer to the first electrode 10 than the second light-emitting layer EML2; the light-emitting device further includes a hole injection layer HIL, a first hole transport layer HTL1 and a first electron blocking layer EBL1 arranged in sequence on the side of the first electrode 10 close to the first light-emitting layer EML1, a first hole blocking layer HBL1, an N-type doped charge generation layer N-CGL, a P-type doped charge generation layer P-CGL, a second hole transport layer HTL2 and a second electron blocking layer EBL2 arranged in sequence on the side of the first light-emitting layer EML1 close to the second light-emitting layer EML2, and an electron injection layer EIL, an electron transport layer ETL and a second hole blocking layer HBL2 arranged in sequence on the side of the second electrode 20 close to the second light-emitting layer EML2.

[0152] The first electrode 10 is an anode of the light-emitting device. For example, the material of the anode can be selected from high work function electrode materials. In the case of a bottom-emitting device, the anode can be selected from, but is not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO) and the like. The thickness of the anode is between 80 nm and 200 nm. In the case of a top-emitting device, the anode can be selected from, but is not limited to, Ag / ITO, Ag / IZO, Ag / SnO2, Ag / ZnO, Al / ITO, Al / IZO and the like. In this case, the thickness of the metal layer (Ag or Al) is between 80 nm and 100 nm, and the thickness of the oxide layer (ITO, IZO, SnO2 or ZnO) is between 5 nm and 20 nm. The average reflectivity of the anode in the visible region is between 85% and 95%.

[0153] The hole injection layer HIL is mainly used to reduce the hole injection barrier and improve the hole injection efficiency. For example, the material of the hole injection layer HIL can be selected from, but is not limited to, HATCN, MnO3, CuPc and the like. Alternatively, the material of the hole injection layer HIL can also be p-doped in the hole transport material, such as NPB:F4TCNQ, TAPC:MnO3 and the like. The thickness of the hole injection layer HIL is between 5 nm and 20 nm, and the p-doping concentration is between 0.5% and 3%. Here, the so-called “p-doping concentration” can be understood as the ratio of the p-doping mass to the sum of the p-doping mass and the mass of the hole transport material.

[0154] The first hole transport layer HTL1 and the second hole transport layer HTL2 are both used for transporting holes. The first hole transport layer HTL1 and the second hole transport layer HTL2 can both be selected from a carbazole material with high hole mobility. The thickness of the first hole transport layer HTL1 and the second hole transport layer HTL2 is between 10 nm and 100 nm.

[0155] The first electron blocking layer EBL1 and the second electron blocking layer EBL2 are both used for blocking electrons and excitons generated in the light-emitting layer EML, and transporting holes. The thickness of the first electron blocking layer EBL1 and the second electron blocking layer EBL2 is between 1 nm and 10 nm. The material of the first electron blocking layer EBL1 or the material of the second electron blocking layer EBL2 can be the same as or different from the molecular formula of the hole transport type material in the light-emitting layer EML (the first light-emitting layer EML1 and the second light-emitting layer EML2).

[0156] The material of the first light-emitting layer EML1 and the material of the second light-emitting layer EML2 both include the host material, the first dopant material and the second dopant material as shown above. The thickness of the first light-emitting layer EML1 or the thickness of the second light-emitting layer EML2 is between 30 nm and 60 nm.

[0157] The first hole blocking layer HBL1 and the second hole blocking layer HBL2 are both used for blocking holes and excitons generated in the light-emitting layer EML, and transporting electrons. The thickness of the first hole blocking layer HBL1 or the thickness of the second hole blocking layer HBL2 is between 1 nm and 10 nm.

[0158] The material of the N-type doped charge generation layer N-CGL is an electron transport type material doped with a low work function active metal. The active metal can include, but is not limited to, Li, Ca, Yb and the like. The doping ratio of the low work function active metal is between 0.6% and 2%, which refers to the ratio of the mass of the low work function active metal to the total mass of the electron transport type material doped with the low work function active metal. The thickness of the N-type doped charge generation layer N-CGL is between 10 nm and 20 nm.

[0159] The material of the P-type doped charge generation layer P-CGL is a hole transport type material doped with a P-type dopant, such as molybdenum oxide. The doping ratio of the P-type dopant is between 5% and 15%, which refers to the ratio of the mass of the P-type dopant to the total mass of the hole transport type material doped with the P-type dopant. The thickness of the P-type doped charge generation layer P-CGL is between 10 nm and 20 nm.

[0160] For example, the N-type doped charge generation layer N-CGL is also an N-type organic semiconductor. The P-type doped charge generation layer P-CGL is also a P-type organic semiconductor. The N-type doped charge generation layer N-CGL and the P-type doped charge generation layer P-CGL can form a P / N junction structure to form electrons and holes. The N-type doped charge generation layer N-CGL injects electrons into the first hole blocking layer HBL1, and the P-type doped charge generation layer P-CGL injects holes into the second hole transport layer HTL2.

[0161] The electron transport layer ETL is mainly used for transporting electrons. The material of the electron transport layer ETL includes an electron transport material and Liq doped together, and the doping mass ratio of the two is 10:1-1:1. The thickness of the electron transport layer ETL is between 10 nm and 50 nm. Liq can be selected from the materials The electron transport material contains at least one group in the group

[0162] The electron injection layer EIL is mainly used to reduce the electron injection barrier and improve the electron injection efficiency. For example, the material of the electron injection layer EIL can be selected from one or more combinations of Yb, Li, LiF, NaCl, CsF, Li2O, BaO, Liq, etc. The thickness of the electron injection layer EIL is between 0.5 nm and 2 nm.

[0163] The second electrode 20 is the cathode of the light-emitting device. For example, the cathode can be selected from low work function electrode materials. For example, the material of the cathode can be selected from, but not limited to, Mg, Ag, Al, Al-Li, Ca, Mg:In, Mg:Ag, etc. In the case of a bottom-emitting device, the thickness of the cathode is between 80 nm and 100 nm. In the case of a top-emitting device, the thickness of the cathode is between 10 nm and 20 nm, and can be prepared by an alloy such as Mg:Ag, and the mass adjustment ratio of Mg:Ag is between 3:7 and 1:9.

[0164] For example, in the case of a top-emitting device, as shown in FIG. 8, the light-emitting device further includes a light extraction layer CPL disposed on the side of the cathode away from the light-emitting layer EML. The light extraction layer CPL covers the cathode and is mainly used to improve the light extraction efficiency and protect the cathode. The thickness of the light extraction layer CPL is between 50 nm and 100 nm, and preferably the refractive index of the material of the light extraction layer CPL at a wavelength of 530 nm should be greater than 1.9 to transmit more light.

[0165] Exemplarily, the light-emitting device further comprises a packaging layer arranged on the side of the CPL facing away from the cathode Cathode. The packaging layer can be packaged by frame glue or by film packaging.

[0166] The device structure of Comparative Example 1 of the tandem light-emitting device comprises: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-1:Ir-1:GD-1, 89.4%:10%:0.6%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (37 nm) → EBL2 (5 nm) → EML2 (P-1:Ir-1:GD-1, 89.4%:10%:0.6%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0167] The device structure of Comparative Example 2 of the tandem light-emitting device comprises: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (N-1:Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (44 nm) → EBL2 (5 nm) → EML2 (N-1:Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0168] The device structure of Comparative Example 3 of the tandem light-emitting device comprises: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (mCBP:Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (42 nm) → EBL2 (5 nm) → EML2 (mCBP:Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm). Wherein, mCBP is a green host material, and its chemical structural formula is

[0169] The device structure of Example 1 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-1 (60):N-1 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (40 nm) → EBL2 (5 nm) → EML2 (P-1 (60):N-1 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0170] The device structure of Example 2 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (60):N-2 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (42 nm) → EBL2 (5 nm) → EML2 (P-2 (60):N-2 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0171] The device structure of Example 3 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-3 (60):N-3 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (40 nm) → EBL2 (5 nm) → EML2 (P-3 (60):N-3 (40):Ir-1:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0172] The device structure of Example 4 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-4 (60):N-2 (40):Ir-2:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (42 nm) → EBL2 (5 nm) → EML2 (P-4 (60):N-2 (40):Ir-2:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0173] The device structure of Example 5 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (60):N-3 (40):Ir-3:GD-2, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (40 nm) → EBL2 (5 nm) → EML2 (P-2 (60):N-3 (40):Ir-3:GD-1, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0174] The device structure of Example 6 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (50):N-3 (50):Ir-3:GD-2, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (41 nm) → EBL2 (5 nm) → EML2 (P-2 (50):N-3 (50):Ir-3:GD-2, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0175] The device structure of Example 7 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (40):N-3 (60):Ir-3:GD-2, 89.1%:10%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (42 nm) → EBL2 (5 nm) → EML2 (P-2 (40):N-3 (60):Ir-3:GD-2, 89.1%:10%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0176] The device structure of Example 8 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (60):N-3 (40):Ir-3:GD-2, 84.1%:15%:0.9%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (41 nm) → EBL2 (5 nm) → EML2 (P-2 (60):N-3 (40):Ir-3:GD-2, 84.1%:15%:0.9%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0177] The device structure of Example 9 of the tandem light emitting device includes: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (60):N-3 (40):Ir-3:GD-2, 88.5%:10%:1.5%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (41 nm) → EBL2 (5 nm) → EML2 (P-2 (60):N-3 (40):Ir-3:GD-2, 88.5%:10%:1.5%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0178] The device structure of embodiment 10 of the tandem light-emitting device comprises: ITO / Ag / ITO (150 nm) → HIL (10 nm) → HTL1 (30 nm) → EBL1 (5 nm) → EML1 (P-2 (60): N-3 (40): Ir-3: GD-2, 83.5%: 15%: 1.5%, 35 nm) → HBL1 (5 nm) → NCGL (15 nm) → PCGL (10 nm) → HTL2 (41 nm) → EBL2 (5 nm) → EML2 (P-2 (60): N-3 (40): Ir-3: GD-2, 83.5%: 15%: 1.5%, 35 nm) → HBL2 (5 nm) → ETL (35 nm) → EIL (1 nm) → Mg:Ag (1:9, 15 nm) → CPL (80 nm).

[0179] For example, each of the above examples (i.e. Comparative Examples 1-3 and Embodiments 1-10) was subjected to device testing. The testing conditions included obtaining the voltage (V) at 15 mA / cm2(current density), current efficiency (CE) of the device using an IVL testing apparatus. Further, the time (LT95) for the luminance of the device to decay from the initial value to 95% under the condition of 1000 cd / m2(luminance) was obtained using a lifetime testing apparatus, and the unit was hour. See Table 3 below. The photoelectric performance of the top-emitting device is shown in Table 5 below. 2 2 95 The time (LT95) for the luminance of the device to decay from the initial value to 95% under the condition of 1000 cd / m2(luminance) was obtained using a lifetime testing apparatus, and the unit was hour. See Table 3 below. The photoelectric performance of the top-emitting device is shown in Table 5 below.

[0180] Table 5

[0181] As shown in Table 5, the iridium complexes obtained by modifying the main ligand with a phenyl group or a phenyl derivative have a high horizontal emission dipole orientation, which is conducive to the FRET energy transfer of the triplet excitons generated by the first dopant material to the singlet state of the second dopant material, and the singlet excitons quickly radiate and decay to emit light, thereby improving the luminous efficiency of the light-emitting device.

[0182] ​​The iridium complex and the fluorescent guest material are doped in the host material, the horizontal emission dipole of the iridium complex obtained after the phenyl or phenyl derivative modifies the host ligand is high, which is conducive to the FRET energy transfer from the triplet exciton generated by the iridium complex to the singlet state of the fluorescent guest material. At the same time, the doping concentration of the host material is between 83% and 94.5%, the doping concentration of the iridium complex is between 15% and 5%, and the doping concentration of the fluorescent guest material is between 2% and 0.5%. Since only a small amount of fluorescent guest material (light emitting material) is doped, the FRET from the iridium complex to the fluorescent guest material is enhanced, the DET from the host material and the iridium complex to the fluorescent guest material is inhibited, and the case that the fluorescent guest material directly captures carriers to emit light is also inhibited. Therefore, the host material and the iridium complex of the present disclosure are basically transferred to the singlet state of the fluorescent guest material through FRET, and the singlet state rapidly radiates and decays to emit light, thereby improving the light emitting efficiency of the light emitting device. In addition, the devices of examples 1-10 have excellent device lifetime.

[0183] For example, FIG. 9 is a schematic diagram of the electroluminescence spectrum of the device corresponding to example 5 of table five, as shown in FIG. 9, wherein the abscissa represents the wavelength of visible light Wavelength (unit: nanometer nm), and the ordinate represents the spectral intensity of the normalized electroluminescence spectrum Intensity. As can be seen, the electroluminescence spectrum of the light emitting device is narrow and has higher stability.

[0184] According to the comparative analysis of the comparative example 1, the comparative example 2 and the example 1 in the above series light emitting device, the first host material of the present disclosure is a hole transport type, and the second host material is an electron transport type, which is combined to form the host material of the light emitting layer EML, which is conducive to improving the exciton utilization rate, expanding the exciton recombination region, and improving the carrier recombination state in the light emitting layer EML, thereby improving the efficiency and lifetime of the light emitting device.

[0185] According to the comparative analysis of the comparative example 3, examples 1-10 in the above series light emitting device, compared with the traditional host material mCBP of the light emitting layer EML, the first host material of the present disclosure is a hole transport type, and the second host material is an electron transport type, which is combined to form the host material of the light emitting layer EML, which is conducive to reducing the voltage of the light emitting device and improving the efficiency and lifetime of the light emitting device.

[0186] According to the comparison of examples 5-10, the pre-mixed ratio of the first host material and the second host material in the light emitting layer EML, the pre-mixed ratio of the host material and the first doping material, and the doping ratio of the final second doping material all affect the device performance of the final light emitting device, therefore, scientific and cautious adjustment of the ratio relationship can also improve the device performance.

[0187] From the test results, it can be seen that the light-emitting device with the structure of the present disclosure has low voltage, high efficiency and long service life.

[0188] In some embodiments, the light-emitting device is an OLED device. Currently, the OLED display has been mass-produced, which can achieve the RGB color purity in accordance with the NTSC standard. However, there is an increasing demand for higher quality displays, such as ultra-high resolution displays. The BT.2020 standard of ultra-high color gamut is generated, which has a red color of (0.708, 0.292), a green color of (0.170, 0.797), and a blue color of (0.131, 0.046). However, the mainstream mass-produced light-emitting material currently uses blue fluorescent material and red and green phosphorescent material, which can only achieve 77% coverage. Among them, the green device color coordinate gap is the most critical factor for realizing the BT.2020 standard. Therefore, the light-emitting device of the present disclosure is a green light-emitting device, which can enable the green light-emitting device to achieve the BT.2020 standard.

[0189] The present disclosure can achieve 100% theoretical exciton efficiency and maintain narrow-band intrinsic spectrum by incorporating the first dopant material belonging to phosphorescent material and the second dopant material belonging to fluorescent material into the host material to form the light-emitting layer EML.

[0190] In addition, the present disclosure also provides a display device comprising the light-emitting device of any one of the above embodiments. The display device may, for example, be a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a vehicle-mounted device, or any product with display function. Other essential components of the display device are understood by those skilled in the art and are not described here, nor should they be considered as limiting the present disclosure.

[0191] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.

Claims

1. A light emitting device, characterized by, The organic light emitting device comprises a first electrode, a second electrode and at least one light emitting layer disposed between the first electrode and the second electrode; The light emitting layer comprises a host material, a first dopant material and a second dopant material doped together; The first dopant material is a phosphorescent material, and the second dopant material is a fluorescent material; The horizontal emission dipole ratio of the first dopant material is between 80% and 100%; Θ / / =p∥ / (p∥+p⊥), wherein Θ / / represents the horizontal emission dipole ratio of the first dopant material, p∥ represents the horizontal emission dipole moment of the first dopant material, and p⊥ represents the vertical emission dipole moment of the first dopant material.

2. The light emitting device of claim 1, wherein The first dopant material is an iridium complex, which is composed of a main ligand, an auxiliary ligand and an iridium ion; wherein the main ligand comprises at least a phenyl group and a phenyl derivative.

3. The light emitting device of claim 2, wherein, The structural general formula (I) of the iridium complex is as follows: wherein, represents a main ligand, represents an auxiliary ligand; In the structural general formula (I), L1-L3 are each independently selected from a substituted or unsubstituted C5-C30 carbocyclic group and a substituted or unsubstituted C1-C30 heterocyclic group, or L1-L3 are each independently selected from an unsubstituted or at least one Q-substituted cyclopentadiene group, a cyclohexane group, a cyclohexene group, a phenyl group, a naphthyl group, an anthracene group, a phenanthrene group, a benzo[9,10]phenanthrene group, a pyrene group, a group, a furan group, a thiophene group, a silole group, an indene group, a fluorene group, an indole group, a carbazole group, a benzofuran group, a dibenzofuran group, a benzothiophene group, a dibenzothiophene group, a benzothiophene group, a dibenzothiophene group, a nitrogen-containing fluorene group, a nitrogen-containing carbazole group, a nitrogen-containing dibenzofuran group, a nitrogen-containing dibenzothiophene group, a nitrogen-containing dibenzothiophene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, a dioxazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzodiazole group, and a benzothiadiazole group; wherein Q is any one of deuterium, -F, -CD3, -CD2H, -CDH2, -CF3, -CF2H, -CFH2, cyano, nitro, C1-C10 alkyl, C1-C10 alkoxy, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, norbornane, norbornene, cyclopentenyl, cyclohexenyl, cycloheptenyl, phenyl, naphthyl, pyridyl, pyrimidyl, dibenzofuranyl, and dibenzothiophenyl. m1-m3 are each independently selected from any integer from 0 to 5; n1-n3 are each independently selected from any integer from 0 to 5; R1-R8 are each independently selected from any one or a combination of more than one of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl, phosphinyl, X, X1-X6are each independently selected from any one of BR, NR, PR, oxygen, sulfur, selenium, carbonyl, acyl, disulfur, CRR', SiRR', GeRR'; wherein R and R' in BR, NR, PR, CRR', SiRR', GeRR' are each independently selected from any one or more of hydrogen, deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, aralkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfenyl, sulfinyl, sulfonyl, phosphinyl; B in BR represents a boron atom; N in NR represents a nitrogen atom; P in PR represents a phosphorus atom; C in CRR' represents a carbon atom; Si in SiRR' represents a silicon atom; Ge in GeRR' represents a germanium atom.

4. The light emitting device of claim 3, wherein, Any adjacent substituents on the same ring group in the structural general formula (I) are joined or fused into a ring.

5. The light emitting device of claim 3, wherein the first and second light emitting devices are arranged in a vertical direction of the substrate. The iridium complex includes any one of the following structures:

6. The light emitting device of claim 1, wherein, In the light-emitting stage, the triplet excitons formed by the host material and the triplet excitons formed by the first dopant material are both transferred to the singlet state light-emitting of the second dopant material through fluorescent resonance energy.

7. The light emitting device of claim 6, wherein the light emitting device is a light emitting diode. The doping concentration of the host material is between 83% and 94.5%; the doping concentration of the host material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material; The doping concentration of the first dopant material is between 15% and 5%; the doping concentration of the first dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material; The doping concentration of the second dopant material is between 2% and 0.5%; the doping concentration of the second dopant material is the ratio of the mass of the host material to the sum of the masses of the host material, the first dopant material and the second dopant material.

8. The light-emitting device according to any one of claims 1 to 7, wherein The ratio of the spectral overlap area between the photoluminescence spectrum of the first dopant material and the absorption spectrum of the second dopant material to the area of the absorption spectrum of the second dopant material is greater than 50%.

9. The light emitting device of claim 8, wherein, The general structure (two) of the second doped material is as follows: wherein ring CY is a C5 to C30 monocyclic group or a fused ring group, or each independently a C5 to C30 monoheterocyclic group or a fused heterocyclic group, wherein the heteroatom is one or more of nitrogen, oxygen, sulfur; R 26 ~R 30 each independently represents one or more combinations of hydrogen, deuterium, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C2 to C30 heteroaryl group; n represents an integer greater than or equal to 1.

10. The light emitting device of claim 8, wherein, The molecular structure of the second dopant material is 11. The light-emitting device of claim 6, wherein, E T1 (Host) > E T1 (Dopant1) > E S1 (Dopant2); wherein E T1 (Host) represents the lowest triplet excited energy of the host material, E T1 (Dopant1) represents the lowest triplet excited energy of the first dopant material, E T1 (Dopant2) represents the lowest triplet excited energy of the second dopant material; E S1 (Host) ≥ E S1 (Dopant1) > E S1 (Dopant2); wherein E S1 (Host) represents the lowest singlet excited energy of the host material, E S1 (Dopant1) the lowest singlet excited energy of the first dopant material, and E (Dopant2) the lowest singlet excited energy of the second dopant material.

12. The light emitting device of claim 1, wherein, The host material comprises a first host material and a second host material; The first host material is a hole-transporting host material; the second host material is an electron-transporting host material.

13. The light emitting device of claim 12, wherein, The ratio of the mass of the first host material to the mass of the second host material is between 1:9 and 5:5; or, the ratio of the mass of the second host material to the mass of the first host material is between 1:9 and 5:

5.

14. The light-emitting device according to any one of claims 1 to 7, wherein The light-emitting device further comprises a hole-transporting layer disposed on the side of the first electrode close to the light-emitting layer, and an electron-transporting layer disposed on the side of the second electrode close to the light-emitting layer.

15. The light-emitting device according to any one of claims 1 to 7, wherein The light-emitting layer comprises a first light-emitting layer and a second light-emitting layer; the first light-emitting layer is closer to the first electrode than the second light-emitting layer; The light emitting device further comprises a first hole transport layer disposed on the first electrode close to the first light emitting layer, a N-type doped charge generation layer and a P-type doped charge generation layer disposed on the first light emitting layer close to the second light emitting layer in sequence, and an electron transport layer disposed on the second electrode close to the second light emitting layer.

16. The light-emitting device according to any one of claims 1 to 7, wherein The light emitting device is a green light emitting device.

17. A display device comprising: A light emitting device comprising any one of claims 1-16.

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