Light-emitting material, light-emitting diode, and display device

Abstract

A luminescent material is provided. The luminescent material has a molecular structural formula of (D) m-(A) q-(D) m '. D represents a donor part of a molecule of the luminescent material, when the molecule is excited, the donor part is configured as an electron donor part of the molecule, and D is at least one part in the molecule which has occupied orbital distribution. A represents an acceptor part of a molecule of the luminescent material, when the molecule is excited, the acceptor part is configured as an electron acceptor part of the molecule, and A is at least one part which does not occupy track distribution in the molecule. M and m'are positive integers greater than 0. Q is a positive integer greater than 1.

Description

Technical Field

[0001] The present invention relates to display technology, and more particularly to a luminescent material, a light emitting diode and a display device. Background Art

[0002] Thermally activated delayed fluorescence (TADF) is a type of fluorescence emitted by a molecular species in a non-emissive excited state that can combine ambient thermal energy to change state and then undergo a radiative transition process. The TADF process involves the conversion of a triplet excited state to a singlet excited state by reverse intersystem crossing (RISC) under activation. The singlet excited state emits fluorescence during the process of deexcitation to the ground state. Along with fluorescent and phosphorescent compounds, TADF compounds are one of the three main luminescent materials used in organic light-emitting diodes (OLEDs). Summary of the invention

[0003] In one aspect, the present disclosure provides a luminescent material having a molecular structural formula of (D)m-(A)q-(D)m'; wherein D represents the donor portion of the molecule of the luminescent material, and when the molecule is excited, the donor portion is configured as the electron donor portion of the molecule, and D is at least one portion of the molecule that has an occupied orbital distribution; A represents the acceptor portion of the molecule of the luminescent material, and when the molecule is excited, the acceptor portion is configured as the electron acceptor portion of the molecule, and A is at least one portion of the molecule that has an unoccupied orbital distribution; m and m' are positive integers greater than 0; and q is a positive integer greater than 1.

[0004] Optionally, the luminescent material has a molecular structure of D1-dA-D2; D1 represents a first donor moiety, D2 represents a second donor moiety; dA includes a first acceptor moiety and a second acceptor moiety; and the first acceptor moiety and the second acceptor moiety are covalently linked to each other.

[0005] Optionally, the luminescent material has a molecular structure of D1-A1-L-A2-D2; D1 represents the first donor portion; D2 represents the second donor portion; A1 represents the first acceptor portion; A2 represents the second acceptor portion; L is a bond, a substituted or unsubstituted alkylene, a substituted or unsubstituted heteroalkylene, a substituted or unsubstituted cycloalkylene, a substituted or unsubstituted heterocycloalkylene, a substituted or unsubstituted arylene, or a substituted or unsubstituted heteroarylene, and n is an integer greater than or equal to 0.

[0006] Alternatively, L is a substituted or unsubstituted arylene group.

[0007] Optionally, L is selected from the group consisting of:

[0008]

[0009] Optionally, the luminescent material has a molecular structure of D1-[A1'-cfg-A2']-D2; D1 represents the first donor part; D2 represents the second donor part; A1'-cfg represents the first acceptor part; cfg-A2' represents the second acceptor part; and the first acceptor part and the second acceptor part share a common functional group cfg.

[0010] Alternatively, the common functional group cfg is a functional group comprising a conjugated diene or a conjugated polyene.

[0011] Optionally, the first acceptor moiety or the second acceptor moiety comprises a phenanthro-azole moiety.

[0012] Optionally, the luminescent material has the following molecular structure:

[0013]

[0014] wherein X is -NH-, -O-, -S-, or N-RO; R0, R1, and R4 are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; L is a bond, substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene; at least one of R2 and R3 is a donor moiety; and at least one of R5 and R6 is a donor moiety.

[0015] Optionally, one of R2 and R3 is a donor moiety; the other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; one of R5 and R6 is a donor moiety and the other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl.

[0016] Optionally, at least one of R2 and R3 is a first aromatic amine group; and at least one of R5 and R6 is a second aromatic amine group.

[0017] Optionally, the first aromatic amine group and the second aromatic amine group are independently:

[0018]

[0019] Optionally, L is a single bond; and the luminescent material has the following molecular structure formula:

[0020]

[0021] Optionally, the luminescent material has the following molecular structure:

[0022]

[0023] wherein X is -NH-, -O-, -S- or N-R0; R0, R1, R4 are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; at least one of R2 and R3 is a donor moiety; and at least one of R5 and R6 is a donor moiety.

[0024] Optionally, one of R2 and R3 is a donor moiety; the other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; one of R5 and R6 is a donor moiety and the other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl.

[0025] Optionally, at least one of R2 and R3 is a first aromatic amine group; and at least one of R5 and R6 is a second aromatic amine group.

[0026] Optionally, the first aromatic amine group and the second aromatic amine group are independently:

[0027]

[0028] Optionally, the luminescent material is selected from the group consisting of:

[0029]

[0030]

[0031]

[0032]

[0033] In another aspect, the present disclosure provides a light emitting diode, comprising an anode, a light emitting material layer, and a cathode located on a side of the light emitting material layer away from the anode; wherein the light emitting material layer comprises the light emitting material described herein.

[0034] Optionally, the light-emitting diode includes: a hole injection layer including 1,4,5,8,9,11-hexaazabenzonitrile; a hole transport layer including N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine; an electron blocking layer including 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole; a luminescent material layer including 9-(3-(9H-carbazole-9-yl)phenyl)-9H-3,9'-bicarbazole doped with the luminescent material described herein; a hole blocking layer including 4,6-bis(3-(9H-carbazole-9-yl)phenyl)pyrimidine; an electron transport layer including 9,10-bis(6-phenylpyridin-3-yl)anthracene; and an electron injection layer including lithium fluoride; wherein the anode includes indium tin oxide; and the cathode includes aluminum.

[0035] Optionally, the light-emitting diode includes: a hole injection layer including 1,4,5,8,9,11-hexaazabenzonitrile; a hole transport layer including 4,4'-cyclohexene [N,N-bis(4-methylphenyl)aniline]; an electron blocking layer including 1,3-di(9H-carbazole-9-yl)benzene; a luminescent material layer including 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl doped with the luminescent material described herein; an electron transport layer including 1,3,5-tri(3-pyridyl-3-phenyl)benzene; and an electron injection layer including lithium fluoride; wherein the anode includes indium tin oxide; and the cathode includes aluminum.

[0036] In another aspect, the present invention provides a display device, comprising the light emitting diode described herein and a pixel driving circuit configured to drive the light emitting diode to emit light. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] According to various disclosed embodiments, the following drawings are examples only for illustration purposes and are not intended to limit the scope of the present invention.

[0038] Figure 1 is a schematic diagram showing the structure of a light-emitting material in some embodiments according to the present disclosure.

[0039] Figure 2 is a schematic diagram showing the structure of a light emitting diode in some embodiments of the present disclosure.

[0040] Figure 3 is a schematic diagram showing the structure of a light emitting diode in some embodiments of the present disclosure.

[0041] Figure 4 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure.

[0042] Figure 5 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure.

[0043] Figure 6 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure.

[0044] Figure 7 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure.

[0045] Figure 8 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure.

[0046] Fig. 9 is a schematic diagram showing the structure of a display substrate in some embodiments of the present disclosure.

[0047] Fig.10 is a circuit diagram showing the structure of a pixel driving circuit in some embodiments according to the present disclosure. DETAILED DESCRIPTION

[0048] The present disclosure will now be described in more detail with reference to the following examples. It should be noted that the following description of some of the embodiments presented herein is for illustration and description purposes only. It is not intended to be exhaustive or limited to the precise form disclosed.

[0049] Thermally activated delayed fluorescent materials have become promising third-generation luminescent materials in the field of organic light-emitting diodes (OLEDs) due to their high exciton utilization efficiency, low cost, and environmental protection. Generally speaking, TADF materials adopt a donor-acceptor (DA) type molecular design, which can effectively separate the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and the singlet-triplet energy gap (ΔE ST ) is small, which is conducive to the formation of singlet excitons via antisystem crossing (RISC) of triplet excitons, thus realizing color-tunable and efficient OLEDs.

[0050] The inventors of the present disclosure have found that there are only a handful of efficient red light TADF materials available. The inventors of the present disclosure have found that the main reasons are as follows: According to the energy gap law, as the emission wavelength increases, the non-radiative transition rate constant (k nr ) increases exponentially, which results in a lower photoluminescence quantum yield (PLQY) of the material in the red wavelength range. Stronger donors or acceptors in red TADF materials fully separate the HOMO and LUMO, which usually leads to a singlet oscillator strength and radiation rate constant (k r) is reduced. The influence of molecular structure (rigidity, planarity, conjugation, etc.) on efficient red light emission is difficult to be fully considered in the molecular design process. The inventors of the present disclosure found that the development of efficient red light TADF materials should focus on suppressing non-radiative deactivation of excitons.

[0051] In the design of novel TADF materials according to the present disclosure, the inventors of the present disclosure took into account several factors, including: twisted DA structure; spatial DA interaction (exciplex-like type); multiple resonance structure; selecting specific D and A chromophores and adjusting their dihedral angles; introducing additional donors to form DAD or DA-D' structures. The inventors of the present disclosure have discovered a new class of TADF materials, which have appropriate spatial interactions, high horizontal dipole ratios, and low non-radiative decay rates, thereby achieving efficient luminescence.

[0052] Therefore, the present disclosure provides, among other things, a light-emitting material, a light-emitting diode, and a display device, which substantially eliminate one or more problems caused by the limitations and disadvantages of the related art. In one aspect, the present disclosure provides a light-emitting material. In some embodiments, the light-emitting material has a molecular structural formula of (D)m-(A)q-(D)m', wherein D represents the donor portion of the molecule of the light-emitting material, and when the molecule is excited, the donor portion is configured as the electron donor portion of the molecule, and D is at least one portion of the molecule with an occupied orbital distribution (for example, the portion with the highest occupied molecular orbital distribution in the molecule); A represents the acceptor portion of the molecule of the light-emitting material, and when the molecule is excited, the acceptor portion is configured as the electron acceptor portion of the molecule, and A is at least one portion of the molecule with an unoccupied orbital distribution (for example, the portion with the lowest unoccupied molecular orbital distribution in the molecule); m and m' are positive integers greater than 0; q is a positive integer greater than 1. Since the horizontal molecular orientation (EDO) is parallel to the molecular orientation and along the long axis of the molecule, the light-emitting material according to the present disclosure achieves a high horizontal dipole ratio (θ / / ). In addition, the luminescent material according to the present disclosure makes the frontier orbital delocalized by Δ EST minimized to obtain excellent electronic properties and improved PLQY.

[0053] In some embodiments, the luminescent material is a thermally activated delayed fluorescent material having two donor parts and two acceptor parts in a single molecule. As used herein, the term "donor" refers to the molecule of the luminescent material being configured as the electron donor part of the molecule when the molecule is excited, and the donor is at least one part of the molecule that has an occupied orbital distribution (for example, the part of the molecule with the highest occupied molecular orbital distribution). The occupied orbitals of the molecule are mainly distributed in the donor. As used herein, the term "acceptor" refers to the molecule of the luminescent material being configured as the electron acceptor part of the molecule when the molecule is excited, and the acceptor is at least one part of the molecule that has an unoccupied orbital distribution (for example, the part of the molecule with the lowest unoccupied molecular orbital distribution). The unoccupied orbitals of the molecule are mainly distributed in the acceptor.

[0054] In some embodiments, the luminescent material has a molecular formula of (D)m-(A)q-(D)m', wherein D represents a donor moiety, A represents an acceptor moiety, and m and m' are positive integers greater than 0 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10). Optionally, q is a positive integer greater than 1 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10). Examples of suitable molecular formulas include D1-dA-D2, D1-tA-D2, D1-qA-D2, D1-qiA-D2, D1-sA-D2, D1-spA-D2, and D1-oA-D2, wherein D1 represents a first donor moiety, D2 represents a second donor moiety, dA includes two acceptor moieties, tA includes three acceptor moieties, qA includes 4 acceptor moieties, qiA includes 5 acceptor moieties, sA includes 6 acceptor moieties, spA includes 7 acceptor moieties, and oA includes 8 acceptor moieties. Examples of suitable molecular structural formulas also include dD1-(A)n-dD2, tD1-(A)n-tD2, qD1-(A)n-qD2, wherein n is a positive integer greater than 0, A represents an acceptor moiety, dD1 includes two donor moieties, dD2 includes two donor moieties, tD1 includes three donor moieties, tD2 includes three donor moieties, qD1 includes four donor moieties, and qD2 includes four donor moieties.

[0055] In some embodiments, the luminescent material has a molecular structure D1-dA-D2, wherein D1 represents a first donor moiety, D2 represents a second donor moiety, and dA includes a first acceptor moiety and a second acceptor moiety. In some embodiments, the first acceptor moiety and the second acceptor moiety are covalently linked to each other. In one example, the first donor moiety and the second donor moiety are the same. In another example, the first donor moiety and the second donor moiety are different from each other. In one example, the first acceptor moiety and the second acceptor moiety are the same. In another example, the first acceptor moiety and the second acceptor moiety are different from each other.

[0056] In some embodiments, dA is -L-, and the light-emitting material has a molecular structure of D1-A1-L-A2-D2, wherein D1 represents a first donor moiety; D2 represents a second donor moiety; A1 represents a first acceptor moiety; A2 represents a second acceptor moiety; L is a bond, a substituted or unsubstituted alkylene, a substituted or unsubstituted heteroalkylene, a substituted or unsubstituted cycloalkylene, a substituted or unsubstituted heterocycloalkylene, a substituted or unsubstituted arylene, or a substituted or unsubstituted heteroarylene, and n is an integer greater than or equal to 0. Alternatively, n is 0, 1 or 2.

[0057] In some embodiments, L is a bond. Alternatively, L is a single bond.

[0058] In some embodiments, L is a substituted or unsubstituted arylene group. In a specific example, L is selected from the group consisting of:

[0059] as well as

[0060] In some embodiments, dA is -[A1'-cfg-A2']-, and the luminescent material has a molecular structure of D1-[A1'-cfg-A2']-D2, wherein D1 represents the first donor moiety, D2 represents the second donor moiety, A1'-cfg represents the first acceptor moiety A1, cfg-A2' represents the second acceptor moiety A2, and the first acceptor moiety A1 and the second acceptor moiety A2 share a common functional group cfg. Optionally, the common functional group cfg is a functional group including a conjugated diene or a conjugated polyene.

[0061] Figure 1 Schematic diagram showing the structure of the light-emitting material in some embodiments of the present disclosure. Figure 1 , the top structure shows the structure of a light-emitting material having a molecular formula of D1-A1-A2-D2, and L is a single bond; the middle structure shows the structure of a light-emitting material having a molecular formula of D1-A1-L-A2-D2, and L is a substituted or unsubstituted arylene group; the bottom structure shows the structure of a light-emitting material having a molecular formula of D1-[A1'-cfg-A2']-D2, wherein A1'-cfg represents A1, and cfg-A2' represents A2. Figure 1As shown, in all three types of molecular structures, any donor-acceptor pair (e.g., D1-A1 or D2-A2) having a donor and an acceptor directly connected to each other has a non-zero (e.g., greater than 20 degrees, greater than 30 degrees, greater than 40 degrees, greater than 50 degrees, greater than 60 degrees, greater than 70 degrees, or greater than 80 degrees) dihedral angle (e.g., twist angle) between the plane of the donor portion and the plane of the acceptor portion. This specific feature increases the volume of the molecule, resulting in reduced molecular aggregation during the process of using the luminescent material to form a luminescent material layer. The luminescent material of the present invention reduces triplet-triplet annihilation (TTA) and singlet-polaron annihilation (SPA). In addition, the first acceptor portion A1 and the second acceptor portion A2 are substantially coplanar, allowing the electronic interaction between the first acceptor portion A1 and the second acceptor portion A2 to regulate the excited state energy level and promote excited state radiation decay.

[0062] In some embodiments, the first acceptor moiety A1 or the second acceptor moiety A2 is a phenanthro-azole moiety. Examples of phenanthro-azole moieties include phenanthro-imidazole moieties, phenanthro-thiazole moieties, and phenanthro-oxazole moieties. The inventors of the present disclosure have found that the phenanthro-azole moieties have high luminous efficiency, suitable bandgap width, excellent thermal stability, and carrier transport capability. The phenanthro-azole moieties with these unique properties exhibit fast radiative decay rates and high PLQY, while promoting device carrier balance and high external quantum efficiency (EQE).

[0063] In some embodiments, the luminescent material has the following molecular formula:

[0064]

[0065] wherein X is -NH-, -O-, -S- or N-R0; R0, R1, and R4 are independently hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14aryl) or substituted or unsubstituted heteroaryl (e.g., 5 to 14-membered heteroaryl including fused ring structures); L is a bond, substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene; at least one of R2 and R3 is a donor moiety; and at least one of R5 and R6 is a donor moiety. Alternatively, one of R2 and R3 is a donor moiety, and the other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14 aryl) or substituted or unsubstituted heteroaryl (e.g., 5 to 14 membered heteroaryl including fused ring structures). Alternatively, one of R5 and R6 is a donor moiety, and the other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14 aryl) or substituted or unsubstituted heteroaryl (e.g., a 5- to 14-membered heteroaryl including a condensed ring structure).

[0066] Optionally, R1 and R4 are independently hydrogen.

[0067] Various suitable donor moieties may be used in the luminescent materials of the present invention. In some embodiments, at least one of R2 and R3 is an aromatic amine group, such as an aromatic tertiary amine group. In some embodiments, at least one of R5 and R6 is an aromatic amine group, such as an aromatic tertiary amine group. Examples of aromatic amine groups include diphenylamine groups, carbazole groups, acridine groups, and phenoxazine groups. Specific examples of aromatic amine groups include:

[0068]

[0069] In some embodiments, L is a single bond. Optionally, the luminescent material has the following molecular structure:

[0070]

[0071] Specific examples of luminescent materials include:

[0072]

[0073] In some embodiments, L is phenyl, biphenyl or naphthyl. Alternatively, L is selected from the group consisting of:

[0074]

[0075] Specific examples of luminescent materials include:

[0076]

[0077]

[0078]

[0079] In some embodiments, the luminescent material has the following molecular formula:

[0080]

[0081] wherein X is -NH-, -O-, -S- or N-R0; R0, R1, and R4 are independently hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14 aryl) or substituted or unsubstituted heteroaryl (e.g., 5 to 14-membered heteroaryl including fused ring structures); at least one of R2 and R3 is a donor moiety; and at least one of R5 and R6 is a donor moiety. Alternatively, one of R2 and R3 is a donor moiety, and the other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14aryl) or substituted or unsubstituted heteroaryl (e.g., 5 to 14 membered heteroaryl including fused ring structures). Alternatively, one of R5 and R6 is a donor moiety, and the other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl (e.g., substituted or unsubstituted C1 to C 20 alkyl), substituted or unsubstituted heteroalkyl (e.g., substituted or unsubstituted 2 to 20 membered heteroalkyl), substituted or unsubstituted cycloalkyl (e.g., C3 to C6 including fused ring structures), 14 cycloalkyl), substituted or unsubstituted heterocycloalkyl (e.g., 3 to 14-membered heterocycloalkyl including fused ring structures), substituted or unsubstituted aryl (e.g., C6 to C 14 aryl) or substituted or unsubstituted heteroaryl (e.g., a 5- to 14-membered heteroaryl including a condensed ring structure).

[0082] Optionally, R1 and R4 are independently hydrogen.

[0083] Various suitable donor moieties may be used in the luminescent materials of the present invention. In some embodiments, at least one of R2 and R3 is an aromatic amine group, such as an aromatic tertiary amine group. In some embodiments, at least one of R5 and R6 is an aromatic amine group, such as an aromatic tertiary amine group. Examples of aromatic amine groups include diphenylamine groups, carbazole groups, acridine groups, and phenoxazine groups. Specific examples of aromatic amine groups include:

[0084]

[0085] Specific examples of luminescent materials include:

[0086]

[0087]

[0088] Various suitable methods may be used to synthesize the light-emitting materials according to the present disclosure.

[0089] In one example, 1 mol of a diphenylimidazole derivative is placed in a benzene solution with iodine under UV light for a photochemical reaction. As a result of the reaction, a phenanthroimidazole derivative is obtained, as shown below:

[0090]

[0091] Under N2 atmosphere, 2mol to 3.5mol of phenanthroimidazole derivative, 1mol of aromatic boric acid compound, 0.05mol of Pd(PPh3)4 catalyst and 0.05mol of K2CO3 are placed in a mixed solution of toluene, ethanol and water. The reaction mixture is heated in a reflux device. The reaction product is extracted and purified by column chromatography to obtain an intermediate. The reaction steps are as follows:

[0092]

[0093] Under N2 atmosphere, 1 mol of the intermediate, 2 to 3.5 mol of the pinacol ester of the intermediate, 0.05 mol of Pd(PPh3)4 catalyst and 0.05 mol of K2CO3 are placed in a mixed solution of toluene, ethanol and water. The reaction mixture is heated in a reflux device. The reaction product is extracted and purified by column chromatography to obtain the intermediate as shown below:

[0094]

[0095] In another example, 2 mol of phenanthroimidazole derivative, 1 mol of 1,4-phenylenediboronic acid, 0.1 mol of Pd(PPh3)4 catalyst and 0.1 mol of K2CO3 were placed in a mixed solution of toluene, ethanol and water under N2 atmosphere. The reaction mixture was heated in a reflux device. The reaction product was extracted and purified by column chromatography as shown below:

[0096]

[0097] In another example, under N2 atmosphere, 2.75mol borate, 1.20mol 2,3-dichloro-1,4-diiodobenzene, 5.00mol LiOH·H2O were added to THF and H2O, followed by 0.063mol Pd2dba3 (0.057g), and 0.25molSPhos, and the mixture was reacted at 50°C for 3 hours. After cooling, the reaction mixture was diluted with ethyl acetate, treated with NH4Cl, and washed with water (20mL) and brine (10mL). After extraction, the intermediate was dried to obtain the intermediate. The intermediate was dissolved in acetone, and an aqueous Na2CO3 solution was added, and the target product was obtained by filtration after 300nm UV irradiation for 46 hours. The reaction is shown below:

[0098]

[0099] Several exemplary reaction products were analyzed. In one example, the reaction product was:

[0100]

[0101] The molecular formula of the reaction product is C 54 H 36 N6; molecular weight is 768.92; theoretical elemental composition is C, 84.35; H, 4.72; N, 10.93; experimental elemental composition is C, 84.31; H, 4.74; N, 10.97. 1H NMR 400 MHz, DMSO-d6) included δ (ppm) = 12.31 (s, 2H, -NH), 9.14 (d, 2H, -Ph), 8.87 (d, 2H, -Ph), 8.46 to 8.41 (m, 4H, -Ph), 8.16 (s, 2H, -Im), 7.91 (s, 2H, -Ph), 7.60 (d, 2H, -Ph), 7.29 to 7.21 (m, 8H, -Ph), 7.10 to 7.00 (m, 12H, -Ph).

[0102] In another example, the reaction product is:

[0103]

[0104] The molecular formula of the reaction product is C 60 H 40 N6; molecular weight is 845.02; theoretical elemental composition is C, 85.28; H, 4.77; N, 9.95; experimental elemental composition is C, 85.30; H, 4.74; N, 9.97. 1 H NMR 400 MHz, DMSO-d6) included δ (ppm) = 12.24 (s, 2H, -NH), 9.10 (d, 2H, -Ph), 8.81 (d, 2H, -Ph), 8.45 to 8.40 (m, 4H, -Ph), 8.17 (s, 2H, -Im), 7.84 (s, 2H, -Ph), 7.61 (d, 2H, -Ph), 7.26 to 7.19 (m, 12H, -Ph), 7.10 to 6.98 (m, 12H, -Ph).

[0105] In another example, the reaction product is:

[0106]

[0107] The molecular formula of the reaction product is C 48 H 32 N6; molecular weight is 692.83; theoretical elemental composition is C, 83.21; H, 4.66; N, 12.13; experimental elemental composition is C, 83.16; H, 4.69; N, 12.18. 1 H NMR 400 MHz, DMSO-d6) included δ (ppm) = 12.17 (s, 2H, -NH), 8.92 (d, 2H, -Ph), 8.23 ​​(s, 2H, -Im), 7.94 (s, 2H, -Ph), 7.78 to 7.64 (m, 4H, -Ph), 7.24 to 7.19 (m, 8H, -Ph), 7.06 to 6.97 (m, 12H, -Ph).

[0108] In another aspect, the present disclosure provides a luminescent material layer comprising the luminescent material herein.

[0109] In another aspect, the present disclosure provides a light emitting diode including a light emitting material layer as described herein. In some embodiments, the light emitting diode includes an anode, a light emitting material layer as described herein, and a cathode located on a side of the light emitting material layer away from the anode.

[0110] Figure 2 Schematic diagram showing the structure of a light emitting diode in some embodiments of the present disclosure. Figure 2 In some embodiments, the light emitting diode includes an anode AD, a hole injection layer HIL on the anode AD, a hole transport layer HTL on a side of the hole injection layer HIL away from the anode AD, an electron blocking layer EBL on a side of the hole transport layer HTL away from the hole injection layer HIL, a light emitting material layer EL on a side of the electron blocking layer EBL away from the hole transport layer HTL, a hole blocking layer HBL on a side of the light emitting material layer EL away from the electron blocking layer EBL, an electron transport layer ETL on a side of the hole blocking layer HBL away from the light emitting material layer EL, an electron injection layer EIL on a side of the electron transport layer ETL away from the hole blocking layer HBL, and a cathode CD on a side of the electron injection layer EIL away from the electron transport layer ETL.

[0111] Figure 3 Schematic diagram showing the structure of a light emitting diode in some embodiments of the present disclosure. Figure 3, the anode of the light-emitting diode includes indium tin oxide ITO having a lowest unoccupied molecular orbital (LUMO) energy level of -5.1 eV. The hole injection layer includes 1,4,5,8,9,11-hexaazabenzonitrile (hexaazatriphenylene hexacarbonitrile, HATCN) having a LUMO energy level of -5.5 eV and a highest occupied molecular orbital (HOMO) energy level of -9.5 eV. The hole transport layer includes N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) having a LUMO energy level of -2.4 eV and a HOMO energy level of -5.4 eV. The electron blocking layer includes 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (BCzPh), which has a LUMO energy level of -2.4 eV and a HOMO energy level of -6.1 eV. The light-emitting material layer includes 9-(3-(9H-carbazole-9-yl)phenyl)-9H-3,9'-bicarbazole (mCPBC, host) doped with an emitter (emitter) (the light-emitting material according to the present disclosure, the guest), which has a LUMO energy level of -2.6eV and a HOMO energy level of -6.1eV. The hole blocking layer includes 4,6-bis(3-(9H-carbazole-9-yl)phenyl)pyrimidine (CzPhPy), which has a LUMO energy level of -2.5eV and a HOMO energy level of -6.5eV. The electron transport layer includes 9,10-bis(6-phenylpyridin-3-yl)anthracene (DPPyA) having a LUMO energy level of -2.7eV and a HOMO energy level of -6.2eV. The electron injection layer includes lithium fluoride (LiF) having a LUMO energy level of -3.0eV. The cathode includes aluminum (Al).

[0112] Hole carriers are transported in the direction of the layer with a high HOMO energy level, and electron carriers are transported in the direction of the layer with a low LUMO energy level. The hole blocking layer blocks hole carriers from entering the luminescent material layer due to the relatively high HOMO energy level of the hole blocking layer. The electron blocking layer blocks electron carriers from entering the luminescent material layer due to the relatively low LUMO energy level of the electron blocking layer. When an electric field is applied, hole carriers overcome the energy level barrier and are injected from the anode into the hole injection layer. The hole carriers are then transported from the hole injection layer to the hole transport layer. The electron carriers overcome the energy level barrier and are injected from the cathode into the electron injection layer. The electron carriers are then transported from the electron injection layer to the electron transport layer. The hole carriers and the electron carriers recombine and emit light in the luminescent material layer.

[0113] In the above exemplary light-emitting diode, the host material of the light-emitting material layer has a relatively high T1 energy level (e.g., 2.8 eV), which effectively prevents energy backflow. The energy transfer efficiency between the host and the guest (the light-emitting material according to the present disclosure) is relatively high. The photoluminescence spectrum of the host (mCPBC) in toluene solution shows a deep blue luminescence centered at 446 nm. The larger the overlapping area between the photoluminescence spectrum of the host and the absorption peak of the guest, the higher the energy transfer efficiency. In addition, the guest (the light-emitting material according to the present disclosure) has a high photoluminescence quantum yield.

[0114] In a specific example, the ITO / HATCN layer has a thickness of 10 nm, the NPB layer has a thickness of 30 nm, the BCzPh layer has a thickness of 10 nm, the luminescent material layer has a thickness of 20 nm, the CzPhPy layer has a thickness of 10 nm, the DPPyA layer has a thickness of 30 nm, the LiF layer has a thickness of 0.5 nm, and the Al layer has a thickness of 150 nm. The luminescent material layer includes 5 wt% of the guest doped in the host. Table 1 lists the parameters of several exemplary light emitting diodes.

[0115] Table 1. Parameters of several exemplary light emitting diodes according to the present disclosure.

[0116]

[0117] In another example, the anode of the light emitting diode includes indium tin oxide ITO having a lowest unoccupied molecular orbital (LUMO) energy level of -5.1 eV. The hole injection layer includes 1,4,5,8,9,11-hexaazabenzonitrile (HATCN) having a LUMO energy level of -5.5 eV and a highest occupied molecular orbital (HOMO) energy level of -9.5 eV. The hole transport layer includes 4,4'-cyclohexene [N,N-bis (4-methylphenyl) aniline] (TAPC) having a LUMO energy level of -2.0 eV and a HOMO energy level of -5.5 eV. The electron blocking layer includes 1,3-bis (9H-carbazole-9-yl) benzene (mCP) having a LUMO energy level of -2.4 eV and a HOMO energy level of -5.9 eV. The light-emitting material layer includes 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl (mCBP, host) doped with an emitter (the light-emitting material according to the present disclosure, the guest), which has a LUMO energy level of -2.4 eV and a HOMO energy level of -6.0 eV. The electron transport layer includes 1,3,5-tri(3-pyridyl-3-phenyl)benzene (TmPyPB) with a LUMO energy level of -2.8 eV and a HOMO energy level of -6.8 eV. The electron injection layer includes lithium fluoride (LiF) with a LUMO energy level of -3.0 eV. The cathode includes aluminum (Al). Table 2 lists the parameters of several exemplary light-emitting diodes.

[0118] Table 2. Parameters of several exemplary light emitting diodes according to the present disclosure.

[0119]

[0120] In some embodiments, the present disclosure provides series-connected light emitting diodes. Figure 4 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure. Figure 4 In some embodiments, the light emitting diode includes an anode AD, a hole injection layer HIL located on the anode AD, a first hole transport layer HTL1 located on a side of the hole injection layer HIL away from the anode AD, a first electron blocking layer EBL1 located on a side of the first hole transport layer HTL1 away from the hole injection layer HIL, a first light emitting material layer EL1 located on a side of the first electron blocking layer EBL1 away from the first hole transport layer HTL1, a first hole blocking layer HBL1 located on a side of the first light emitting material layer EL1 away from the first electron blocking layer EBL1, a first electron transport layer ETL1 located on a side of the first hole blocking layer HBL1 away from the first light emitting material layer EL1, a charge generating layer CGL located on a side of the first electron transport layer ETL1 away from the first hole blocking layer HBL1, and a cathode ray tube located on a cathode ray tube. A second hole transport layer HTL2 on the side of the charge generation layer CGL away from the first electron transport layer ETL1, a second electron blocking layer EBL2 on the side of the second hole transport layer HTL2 away from the charge generation layer CGL, a second light-emitting material layer EL2 on the side of the second electron blocking layer EBL2 away from the second hole transport layer HTL2, a second hole blocking layer HBL2 on the side of the second light-emitting material layer EL2 away from the second electron blocking layer EBL2, a second electron transport layer ETL2 on the side of the second hole blocking layer HBL2 away from the second light-emitting material layer EL2, an electron injection layer EIL on the side of the second electron transport layer ETL2 away from the second hole blocking layer HBL2, and a cathode CD on the side of the electron injection layer EIL away from the second electron transport layer ETL2.

[0121] In some embodiments, the charge generation layer CGL includes an n-doped layer N-CGL and a p-doped layer P-CGL located on a side of the n-doped layer N-CGL away from the first electron transport layer ETL1. The n-doped layer N-CGL and the p-doped layer P-CGL are directly connected to each other to form a pn junction. In the pn junction, a depletion region is formed in which electrons of the n-doped layer N-CGL migrate to the p-doped layer P-CGL.

[0122] The n-doped layer N-CGL may be manufactured using various suitable n-doped materials. The p-doped layer P-CGL may be manufactured using various suitable p-doped materials. The n-doped layer N-CGL and the p-doped layer P-CGL may include one or more organic and / or inorganic materials as a matrix. The matrix is ​​mixed with one or more organic or inorganic dopants to increase the conductivity of the matrix. Examples of dopants for the n-doped layer N-CGL include metals with a low work function, such as Na, Ca, Cs, Li, Mg or compounds thereof, such as Cs2CO3, Cs3PO4, or organic dopants, such as NDN-1, NDN-26. Examples of dopants for the p-doped layer P-CGL include transition metal oxides, such as MoOx, WOx, VOx, organic compounds, such as Cu(I)pFBz, F4-TCNQ, or organic dopants, such as NDP-2, NDP-9.

[0123] Figure 5 Schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure. Figure 5 , the anode of the light-emitting diode includes indium tin oxide ITO having a LUMO energy level of -5.1 eV. The hole injection layer includes 1,4,5,8,9,11-hexaazabenzonitrile (HATCN) having a LUMO energy level of -5.5 eV and a HOMO energy level of -9.5 eV. The first hole transport layer and the second hole transport layer include N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) having a LUMO energy level of -2.4 eV and a HOMO energy level of -5.4 eV. The first electron blocking layer and the second electron blocking layer include 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (BCzPh), which has a LUMO energy level of -2.4 eV and a HOMO energy level of -6.1 eV. The first light-emitting material layer and the second light-emitting material layer include 9-(3-(9H-carbazole-9-yl)phenyl)-9H-3,9'-bicarbazole (mCPBC, host) doped with an emitter (a light-emitting material according to the present disclosure, a guest), which has a LUMO energy level of -2.6 eV and a HOMO energy level of -6.1 eV. The first hole blocking layer and the second hole blocking layer include 4,6-bis(3-(9H-carbazole-9-yl)phenyl)pyrimidine (CzPhPy), which has a LUMO energy level of -2.5 eV and a HOMO energy level of -6.5 eV. The first electron transport layer and the second electron transport layer include 9,10-bis(6-phenylpyridin-3-yl)anthracene (DPPyA) having a LUMO energy level of -2.7 eV and a HOMO energy level of -6.2 eV. The electron injection layer includes lithium fluoride (LiF) having a LUMO energy level of -3.0 eV. The cathode includes aluminum (Al).

[0124] The n-doped layer N-CGL includes 2 wt% Li in 4,7-diphenyl-1,10-phenanthroline (BPhen) with a LUMO level of -3.0 eV and a HOMO level of -6.4 eV. The p-doped layer P-CGL includes 10 wt% 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) in (NPD) with a LUMO level of -5.2 eV and a HOMO level of -8.3 eV. Table 3 lists the parameters of several exemplary light emitting diodes.

[0125] In one example, Figure 5 The light emitting diodes shown are single color (eg, red) series-connected light emitting diodes.

[0126] Table 3. Parameters of several exemplary light emitting diodes according to the present disclosure.

[0127]

[0128] Various suitable embodiments may be practiced in the present disclosure.In some embodiments, the light emitting diode is a white series light emitting diode. Figure 6 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure. Figure 6 In some embodiments, the light emitting diode includes an anode AD, a hole injection layer HIL located on the anode AD, a first hole transport layer HTL1 located on a side of the hole injection layer HIL away from the anode AD, a first light emitting material layer EL1 located on a side of the first hole transport layer HTL1 away from the hole injection layer HIL, a second light emitting material layer EL2 located on a side of the first light emitting material layer EL1 away from the first hole transport layer HTL1, a first electron transport layer ETL1 located on a side of the second light emitting material layer EL2 away from the first light emitting material layer EL1, and a first electron transport layer ETL1 located on a side of the first electron transport layer ETL1 away from the second light emitting material layer An n-doped layer N-CGL on one side of layer EL2, a p-doped layer P-CGL located on the side of the n-doped layer N-CGL away from the first electron transport layer ETL1, a second hole transport layer HTL2 located on the side of the p-doped layer P-CGL away from the n-doped layer N-CGL, a third light-emitting material layer EL3 located on the side of the second hole transport layer HTL2 away from the p-doped layer P-CGL, a second electron transport layer ETL2 located on the side of the third light-emitting material layer EL3 away from the second hole transport layer HTL2, and a cathode CD located on the side of the second electron transport layer ETL2 away from the third light-emitting material layer EL3.

[0129] Figure 7 is a schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure. Figure 7In some embodiments, the light emitting diode includes an anode AD, a hole injection layer HIL located on the anode AD, a first hole transport layer HTL1 located on a side of the hole injection layer HIL away from the anode AD, a third light emitting material layer EL3 located on a side of the first hole transport layer HTL1 away from the hole injection layer HIL, a first electron transport layer ETL1 located on a side of the third light emitting material layer EL3 away from the first hole transport layer HTL1, an n-doped layer N-CGL located on a side of the first electron transport layer ETL1 away from the third light emitting material layer EL3, and a first electron transport layer ETL2 located on a side of the n-doped layer N-CGL away from the first electron transport layer ETL1. A p-doped layer P-CGL on one side of TL1, a second hole transport layer HTL2 located on the side of the p-doped layer P-CGL away from the n-doped layer N-CGL, a first light-emitting material layer EL1 located on the side of the second hole transport layer HTL2 away from the p-doped layer P-CGL, a second light-emitting material layer EL2 located on the side of the first light-emitting material layer EL1 away from the second hole transport layer HTL2, a second electron transport layer ETL2 located on the side of the second light-emitting material layer EL2 away from the first light-emitting material layer EL1, and a cathode CD located on the side of the second electron transport layer ETL2 away from the second light-emitting material layer EL2.

[0130] The light-emitting material layer according to the present disclosure can be implemented as any one of the first light-emitting material layer EL1, the second light-emitting material layer EL2, and the third light-emitting material layer EL3. In one example, the first light-emitting material layer EL1 is a light-emitting material layer of a first color, the second light-emitting material layer EL2 is a light-emitting material layer of a second color, and the third light-emitting material layer EL3 is a light-emitting material layer of a third color. In one example, the first color is red, the second color is green, and the third color is blue. In another example, the light-emitting diode is configured to emit white light.

[0131] In some embodiments, the first light-emitting material layer EL1 includes a light-emitting material according to the present disclosure. In some embodiments, the second light-emitting material layer EL2 includes a light-emitting material according to the present disclosure. In some embodiments, the third light-emitting material layer EL3 includes a light-emitting material according to the present disclosure. In some embodiments, any two or all of the first light-emitting material layer EL1, the second light-emitting material layer EL2, and the third light-emitting material layer EL3 include a light-emitting material according to the present disclosure (for example, each having a different color).

[0132] Figure 8 Schematic diagram showing the structure of series-connected light-emitting diodes in some embodiments of the present disclosure. Figure 8In some embodiments, the light emitting diode includes three separate stacked structures. In some embodiments, the light emitting diode includes several common layers shared by the three separate stacked structures. In some embodiments, the several common layers include a p-type hole transport layer p-HTL, a first hole transport layer HTL1 located on the p-type hole transport layer p-HTL, and a second hole transport layer HTL2 located on a side of the first hole transport layer HTL1 away from the p-type hole transport layer p-HTL. In some embodiments, the first stacked structure further includes a first light-emitting material layer EL1-1 of the first color located on a side of the second hole transport layer HTL2 away from the first hole transport layer HTL1, a first electron transport layer ETL1 located on a side of the first light-emitting material layer EL1-1 of the first color away from the second hole transport layer HTL2, an n-doped layer N-CGL located on a side of the first electron transport layer ETL1 away from the first light-emitting material layer EL1-1 of the first color, a p-doped layer P-CGL located on a side of the n-doped layer N-CGL away from the first electron transport layer ETL1, and a third hole transport layer HTL located on a side of the p-doped layer P-CGL away from the n-doped layer N-CGL. 3. A fourth hole transport layer HTL4 located on a side of the third hole transport layer HTL3 away from the p-doped layer P-CGL, a first color second light-emitting material layer EL1-2 located on a side of the fourth hole transport layer HTL4 away from the third hole transport layer HTL3, an electron transport layer ETL located on a side of the first color second light-emitting material layer EL1-2 away from the fourth hole transport layer HTL4, an electron injection layer EIL located on a side of the electron transport layer ETL away from the first color second light-emitting material layer EL1-2, a cathode CD located on a side of the electron injection layer EIL away from the electron transport layer ETL, and a covering layer CPL located on a side of the cathode CD away from the electron injection layer EIL.

[0133] In some embodiments, the second stacked structure further includes a first light-emitting material layer EL2-1 of a second color located on a side of the second hole transport layer HTL2 away from the first hole transport layer HTL1, a first electron transport layer ETL1 located on a side of the first light-emitting material layer EL2-1 of the second color away from the second hole transport layer HTL2, an n-doped layer N-CGL located on a side of the first electron transport layer ETL1 away from the first light-emitting material layer EL2-1 of the second color, a p-doped layer P-CGL located on a side of the n-doped layer N-CGL away from the first electron transport layer ETL1, and a third hole transport layer HTL located on a side of the p-doped layer P-CGL away from the n-doped layer N-CGL. 3. A fourth hole transport layer HTL4 located on a side of the third hole transport layer HTL3 away from the p-doped layer P-CGL, a second color second light-emitting material layer EL2-2 located on a side of the fourth hole transport layer HTL4 away from the third hole transport layer HTL3, an electron transport layer ETL located on a side of the second color second light-emitting material layer EL2-2 away from the fourth hole transport layer HTL4, an electron injection layer EIL located on a side of the electron transport layer ETL away from the second color second light-emitting material layer EL2-2, a cathode CD located on a side of the electron injection layer EIL away from the electron transport layer ETL, and a covering layer CPL located on a side of the cathode CD away from the electron injection layer EIL.

[0134] In some embodiments, the third stacked structure further includes a first light-emitting material layer EL3-1 of a third color located on a side of the second hole transport layer HTL2 away from the first hole transport layer HTL1, a first electron transport layer ETL1 located on a side of the first light-emitting material layer EL3-1 of the third color away from the second hole transport layer HTL2, an n-doped layer N-CGL located on a side of the first electron transport layer ETL1 away from the first light-emitting material layer EL3-1 of the third color, a p-doped layer P-CGL located on a side of the n-doped layer N-CGL away from the first electron transport layer ETL1, and a third hole transport layer HTL located on a side of the p-doped layer P-CGL away from the n-doped layer N-CGL. 3. A fourth hole transport layer HTL4 located on a side of the third hole transport layer HTL3 away from the p-doped layer P-CGL, a second light-emitting material layer EL3-2 of a third color located on a side of the fourth hole transport layer HTL4 away from the third hole transport layer HTL3, an electron transport layer ETL located on a side of the second light-emitting material layer EL3-2 of the third color away from the fourth hole transport layer HTL4, an electron injection layer EIL located on a side of the electron transport layer ETL away from the second light-emitting material layer EL3-2 of the third color, a cathode CD located on a side of the electron injection layer EIL away from the electron transport layer ETL, and a covering layer CPL located on a side of the cathode CD away from the electron injection layer EIL.

[0135] In one example, the first color is red, the second color is green, and the third color is blue. In another example, the light emitting diode is configured to emit white light.

[0136] In another aspect, the present invention provides a display substrate, comprising a light emitting diode as described herein or a light emitting diode manufactured by the method as described herein, and a pixel driving circuit configured to drive the light emitting diode to emit light.

[0137] Fig. 9 Schematic diagram showing the structure of a display substrate in some embodiments of the present disclosure. Fig. 9 In some embodiments, the display substrate includes a base substrate BS; an active layer ACT of a corresponding one of a plurality of thin film transistors TFT on the base substrate BS; a gate insulating layer GI, which is located on a side of the active layer ACT away from the base substrate BS; a gate G and a first capacitor electrode Ce1 (both are part of the first gate metal layer), which are located on a side of the gate insulating layer GI away from the base substrate BS; an insulating layer IN, which is located on a side of the gate G and the first capacitor electrode Ce1 away from the gate insulating layer GI; a second capacitor electrode Ce2 (a part of the second gate metal layer), which is located on a side of the insulating layer IN away from the gate insulating layer GI; an interlayer dielectric layer ILD, which is located on a side of the second capacitor electrode Ce2 away from the gate insulating layer GI; a source S and a drain D (part of the first SD metal layer), which is located on the side of the interlayer dielectric layer ILD away from the gate insulating layer GI; the passivation layer PVX, which is located on the side of the source S and the drain D away from the interlayer dielectric layer ILD; the first planarization layer PLN1, which is located on the side of the passivation layer PVX away from the interlayer dielectric layer ILD; the relay electrode RE (part of the second SD metal layer), which is located on the side of the first planarization layer PLN1 away from the passivation layer PVX; the second planarization layer PLN2, which is located on the side of the relay electrode RE (part of the second SD metal layer) away from the first planarization layer PLN1; the pixel defining layer PDL, which defines the sub-pixel opening and is located on the side of the second planarization layer PLN2 away from the substrate BS; and the light emitting diode LE in the sub-pixel opening. The light emitting diode LE includes an anode AD located on a substrate BS; a hole injection layer HIL located on a side of the anode AD away from the substrate BS; a hole transport layer HTL located on a side of the hole injection layer HIL away from the substrate BS; a light emitting material layer EL located on a side of the hole transport layer HTL away from the substrate BS; an electron transport layer ETL located on a side of the light emitting material layer EL away from the substrate BS; an electron injection layer EIL located on a side of the electron transport layer ETL away from the substrate BS; and a cathode CD located on a side of the electron injection layer EIL away from the substrate BS.

[0138] The display substrate further includes an encapsulation layer EN in the display area, which encapsulates the light emitting element LE and is located on the side of the cathode layer CD away from the base substrate BS. In some embodiments, the encapsulation layer EN includes a first inorganic encapsulation sublayer CVD1 located on the side of the cathode layer CD away from the base substrate BS, an organic encapsulation sublayer IJP located on the side of the first inorganic encapsulation sublayer CVD1 away from the base substrate BS, and a second inorganic encapsulation sublayer CVD2 located on the side of the organic encapsulation sublayer IJP away from the base substrate BS.

[0139] In some embodiments, the display substrate further includes a touch structure TS. In some embodiments, the touch structure TS includes a buffer layer BUF, which is located on a side of the encapsulation layer EN away from the base substrate BS; a first touch electrode layer TE1, which is located on a side of the buffer layer BUF away from the encapsulation layer EN; a touch insulation layer TI, which is located on a side of the first touch electrode layer TE1 away from the buffer layer BUF; a second touch electrode layer TE2, which is located on a side of the touch insulation layer TI away from the buffer layer BUF; and an overcoat layer OC, which is located on a side of the second touch electrode layer TE2 away from the touch insulation layer TI.

[0140] Fig.10 is a circuit diagram showing the structure of a pixel driving circuit in some embodiments of the present disclosure. Fig.10In some embodiments, each pixel driving circuit includes: a driving transistor Td; a storage capacitor Cst having a first capacitor electrode Ce1 and a second capacitor electrode Ce2; a first transistor T1 having a gate connected to a corresponding reset control signal line rstN in a current stage (or a current row) among a plurality of reset control signal lines, a first electrode connected to a corresponding first reset signal line Vint1N in a current stage (or a current row) among a plurality of first reset signal lines, and a second electrode connected to the first capacitor electrode Ce1 of the storage capacitor Cst and the gate of the driving transistor Td; a second transistor T2 having a gate connected to a corresponding gate line GL among a plurality of gate lines, a first electrode connected to a corresponding data line DL among a plurality of data lines, and a second electrode connected to the first electrode of the driving transistor Td; a third transistor T3 having a gate connected to the corresponding gate line, a first electrode connected to the first capacitor electrode Ce1 of the storage capacitor Cst and the gate of the driving transistor Td, and a second electrode connected to the gate of the first capacitor electrode Ce1 of the storage capacitor Cst and the gate of the driving transistor Td; a second electrode connected to the second electrode of the driving transistor Td; a fourth transistor T4 having a gate connected to a corresponding light emitting control signal line among a plurality of light emitting control signal lines em, a first electrode connected to a corresponding voltage supply line among a plurality of voltage supply lines Vdd, and a second electrode connected to the first electrode of the driving transistor Td and the second electrode of the second transistor T2; a fifth transistor T5 having a gate connected to a corresponding light emitting control signal line, a first electrode connected to the second electrodes of the driving transistor Td and the third transistor T3, and a second electrode connected to the anode of the light emitting element LE; and a sixth transistor T6 having a gate connected to a corresponding reset control signal line rst(N+1) in a next adjacent stage (or a next adjacent row) among a plurality of reset control signal lines, a first electrode connected to a corresponding second reset signal line Vint2N in a current stage (or a current row) among a plurality of second reset signal lines, and a second electrode connected to the second electrode of the fifth transistor and the anode of the light emitting element LE. The second capacitor electrode Ce2 is connected to the corresponding voltage supply line and the first electrode of the fourth transistor T4.

[0141] In another aspect, the present invention provides a display device comprising a display substrate as described herein or a display substrate manufactured by the method described herein, and one or more integrated circuits connected to the display substrate. Examples of suitable display devices include, but are not limited to, electronic paper, mobile phones, tablet computers, televisions, monitors, notebook computers, digital photo albums, GPS, etc. Optionally, the display device is an organic light emitting diode display device. Optionally, the display device is a mini light emitting diode display device. Optionally, the display device is a quantum dot light emitting diode display device.

[0142] For the purpose of illustration and description, the above description of the embodiments of the present invention has been given. It is not exhaustive, nor is it intended to limit the present invention to the precise form or exemplary embodiments disclosed. Therefore, the foregoing description should be considered illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to those skilled in the art. The embodiments are selected and described to explain the principles of the present invention and its best mode practical application, so that those skilled in the art can understand the various embodiments of the present invention and the various modifications suitable for the specific use or implementation under consideration. The scope of the present invention is intended to be defined by the appended claims and their equivalents, wherein all terms are meant to have the broadest reasonable meaning unless otherwise stated. Therefore, the term "the present invention" and the like do not necessarily limit the scope of the claims to a specific embodiment, and the reference to the exemplary embodiments of the present invention does not mean a limitation of the present invention, and such limitation should not be inferred. The present invention is limited only by the spirit and scope of the appended claims. In addition, these claims may involve the use of "first", "second", etc., followed by a noun or element. These terms should be understood as nomenclature, and should not be interpreted as limiting the number of elements modified by these nomenclatures, unless a specific number has been given. Any advantages and benefits described may not apply to all embodiments of the present invention. It should be understood that those skilled in the art may make changes to the described embodiments without departing from the scope of the present invention as defined by the appended claims. In addition, the elements and assemblies in this disclosure are not intended to be contributed to the public, regardless of whether the element or assembly is clearly described in the appended claims.

Claims

1. A luminescent material having a molecular structure of (D)m-(A)q-(D)m'; in, D represents a donor portion of a molecule of the luminescent material, which is configured as an electron donor portion of the molecule when the molecule is excited, and D is a portion of the molecule that has at least one occupied orbital distribution; A represents an acceptor portion of a molecule of the luminescent material, which is configured as an electron acceptor portion of the molecule when the molecule is excited, and A is a portion of the molecule that has at least one unoccupied orbital distribution; m and m' are positive integers greater than 0; as well as q is a positive integer greater than 1.

2. The luminescent material according to claim 1, wherein The luminescent material has a molecular structure of D1-dA-D2; D1 represents the first donor part, and D2 represents the second donor part; dA comprises a first receptor portion and a second receptor portion; as well as The first receptor moiety and the second receptor moiety are covalently linked to each other.

3. The luminescent material according to claim 2, wherein The luminescent material has a molecular structure of D1-A1-L-A2-D2; D1 represents the first donor moiety; D2 represents the second donor moiety; A1 represents the first receptor moiety; A2 represents the second receptor moiety; L is a bond, substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene, and n is an integer greater than or equal to 0.

4. The luminescent material according to claim 3, wherein L is a substituted or unsubstituted arylene group.

5. The luminescent material according to claim 4, wherein L is selected from the group consisting of:

6. The luminescent material according to claim 2, wherein The luminescent material has a molecular structure of D1-[A1'-cfg-A2']-D2; D1 represents the first donor moiety; D2 represents the second donor moiety; A1'-cfg represents the first receptor part; cfg-A2' represents the second receptor part; as well as The first receptor moiety and the second receptor moiety share a common functional group cfg.

7. The luminescent material according to claim 6, wherein The common functional group cfg is a functional group including a conjugated diene or a conjugated polyene.

8. The luminescent material according to claim 2, wherein The first acceptor moiety or the second acceptor moiety comprises a phenanthro-azole moiety.

9. The luminescent material according to claim 1, wherein The luminescent material has the following molecular structure: Wherein, X is -NH-, -O-, -S- or N-R0; R0, R1, R4 are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; L is a bond, substituted or unsubstituted alkylene, substituted or unsubstituted heteroalkylene, substituted or unsubstituted cycloalkylene, substituted or unsubstituted heterocycloalkylene, substituted or unsubstituted arylene, or substituted or unsubstituted heteroarylene; At least one of R2 and R3 is a donor moiety; and At least one of R5 and R6 is a donor moiety.

10. The luminescent material according to claim 9, wherein One of R2 and R3 is a donor moiety; The other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; One of R5 and R6 is a donor moiety, and The other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl.

11. The luminescent material according to claim 9, wherein At least one of R2 and R3 is a first aromatic amine group; and At least one of R5 and R6 is a second aromatic amine group.

12. The luminescent material according to claim 9, wherein The first aromatic amine group and the second aromatic amine group are independently:

13. The luminescent material according to claim 9, wherein L is a single bond; and The luminescent material has the following molecular structure:

14. The luminescent material according to claim 1, wherein The luminescent material has the following molecular structure: Wherein, X is -NH-, -O-, -S- or N-R0; R0, R1, R4 are independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; At least one of R2 and R3 is a donor moiety; and At least one of R5 and R6 is a donor moiety.

15. The luminescent material according to claim 14, wherein One of R2 and R3 is a donor moiety; The other of R2 and R3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; One of R5 and R6 is a donor moiety, and The other of R5 and R6 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl.

16. The luminescent material according to claim 14, wherein At least one of R2 and R3 is a first aromatic amine group; and At least one of R5 and R6 is a second aromatic amine group.

17. The luminescent material according to claim 14, wherein The first aromatic amine group and the second aromatic amine group are independently:

18. The luminescent material according to claim 1, wherein The luminescent material is selected from the group consisting of:

19. A light emitting diode, comprising an anode, a light emitting material layer and a cathode located on a side of the light emitting material layer away from the anode; in, The luminescent material layer comprises the luminescent material according to any one of claims 1 to 18.

20. The light emitting diode according to claim 19, comprising: a hole injection layer comprising 1,4,5,8,9,11-hexaazabenzonitrile; a hole transport layer comprising N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine; an electron blocking layer comprising 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole; A light-emitting material layer comprising 9-(3-(9H-carbazol-9-yl)phenyl)-9H-3,9'-bicarbazole doped with the light-emitting material according to any one of claims 1 to 18; a hole blocking layer comprising 4,6-bis(3-(9H-carbazol-9-yl)phenyl)pyrimidine; an electron transport layer comprising 9,10-bis(6-phenylpyridin-3-yl)anthracene; and an electron injection layer comprising lithium fluoride; wherein the anode comprises indium tin oxide; and The cathode includes aluminum.

21. The light emitting diode according to claim 19, comprising: a hole injection layer comprising 1,4,5,8,9,11-hexaazabenzonitrile; a hole transport layer comprising 4,4'-cyclohexene[N,N-bis(4-methylphenyl)aniline]; an electron blocking layer comprising 1,3-di(9H-carbazol-9-yl)benzene; A light-emitting material layer comprising 3,3'-di(9H-carbazole-9-yl)-1,1'-biphenyl doped with the light-emitting material according to any one of claims 1 to 18; an electron transport layer comprising 1,3,5-tris(3-pyridyl-3-phenyl)benzene; and an electron injection layer comprising lithium fluoride; wherein the anode comprises indium tin oxide; and The cathode includes aluminum. 22 . A display device, comprising a light emitting diode according to claim 19 , and a pixel driving circuit, wherein the pixel driving circuit is configured to drive the light emitting diode to emit light.

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