Quantum dot materials and light-emitting devices

Abstract

The present invention provides a quantum dot material and a light-emitting device, wherein the quantum dot material comprises a quantum dot and a ligand connected to the quantum dot by a coordination bond, wherein the ligand has a structure as shown in Formula 1: wherein D represents an electron-donating group; A represents a chain group; represents a group containing N and a substituted or unsubstituted aromatic ring, wherein the substituent of the substituted aromatic ring is selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group. The present invention can improve the performance of the device, such as efficiency and lifespan.

Description

Technical Field

[0001] The invention relates to a quantum dot material and a light-emitting device, belonging to the technical field of display. Background Art

[0002] Quantum dot light-emitting diodes have the advantages of high color gamut, long potential life, good viewing angle, and low cost, and are very promising light-emitting devices. However, the efficiency and life of light-emitting devices are currently poor and need to be improved urgently. Summary of the invention

[0003] The present invention provides a quantum dot material and a light-emitting device, so as to at least solve the technical problems existing in the prior art such as poor device efficiency and life span.

[0004] In one aspect of the present invention, a quantum dot material is provided, comprising a quantum dot and a ligand connected to the quantum dot via a coordination bond, wherein the ligand has a structure as shown in Formula 1 below:

[0005]

[0006] Wherein, D represents an electron-donating group;

[0007] A represents a chain group;

[0008] represents a group containing N and a substituted or unsubstituted aromatic ring, wherein the substituent of the substituted aromatic ring is selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group.

[0009] In some embodiments, D is selected from a phosphorus oxygen group, an organic phosphorus group, an amino group, a carboxyl group, and a thiol group.

[0010] In some embodiments, the A comprises a segment having a structure as shown in the following formula 1-A:

[0011]

[0012] Among them, R 3 , R 4 , R 5 , R 6 Each is independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and heteroatom-containing electron-donating substituents;

[0013] z is selected from O, S, -NR or R, R 7 , R 8 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl;

[0014] n1 、n 2 are each independently 0 or a positive integer, and n 1 +n 2 ≥1.

[0015] In some embodiments, the number of carbon atoms in A is greater than or equal to 2; preferably, the number of carbon atoms in A is greater than or equal to 4; preferably, the number of carbon atoms in A is less than or equal to 40.

[0016] In some embodiments, the substituted or unsubstituted aromatic ring is selected from a substituted or unsubstituted benzene ring;

[0017] and / or, the carbon number of the substituted or unsubstituted alkyl group is greater than or equal to 3, preferably, the carbon number of the substituted or unsubstituted alkyl group is 3-10;

[0018] and / or, the substituent of the substituted aryl group and the substituent of the substituted heteroaryl group are each independently selected from a substituted or unsubstituted alkyl group, the number of carbon atoms of the substituted or unsubstituted alkyl group is greater than or equal to 3, preferably, the number of carbon atoms of the substituted or unsubstituted alkyl group is 3-10;

[0019] and / or, the heteroatom in the heteroaryl group is selected from one or more of O, S, and N; and / or, the substituted or unsubstituted aryl group or the substituted or unsubstituted heteroaryl group is connected to the aromatic ring via a single bond or a ring connection;

[0020] And / or, the number of substituents on the aromatic ring is less than or equal to 5.

[0021] In some embodiments, the It has the structure shown in the following formula 1-N:

[0022]

[0023] Wherein, a dotted line indicates that the carbon atoms at both ends of the dotted line are connected or not connected to each other;

[0024] R 1 , R 2 Each independently represents a single substitution to the maximum permissible substituent, and R 1 , R 2 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R 14 , R 15 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; R 1 , R 2 Each is independently connected to the benzene ring where it is located by a single bond or a ring connection.

[0025] In some embodiments, the Has the following formula 1-N 1 Or 1-N 2 The structure shown:

[0026]

[0027] In some embodiments, the ligand is selected from Ligands B1-B14.

[0028] In some embodiments, the quantum dots have a core-shell structure.

[0029] Preferably, the core of the core-shell structure contains at least one of CdSe, CdSeS, CdZnSe, CdZnSeS, CdS, CdZnS, InP, InZnP, InGaP, GaP, ZnTeSe, ZnSe, ZnTe, CuInS, CuInZnS, CuInZnSe, AgInZnSe, CuInSe, AgInSe, AgS, AgSe, AgSeS, PbS, PbSe, PbSeS, PbTe, HgS, HgSe, HgTe, CdHgTe, CgHgSe, CdHgS, CdTe, CdZnTe, CdTeSe, and CdTeS.

[0030] Preferably, the shell of the core-shell structure comprises ZnS, ZnSe, ZnSeS, ZnN, ZnS, AlSb, ZnP, InP, AlS, PbS, HgS, AgS, ZnInS, ZnAlS, ZnSeS, CdSeS, CuInS, CuGaS, CuAlS, AgInS, AgAlS, AgGaS, ZnInP, ZnGaP, CdZnS, CdPbS, CdHgS, PbHgS , CdZnPbS, CdZnHgS, CdInZnS, CdAlZnS, CdSeZnS, AgInZnS, CuInZnS, AgGaZnS, CuGaZnS, CuZnSnS , at least one of CuAlZnS, CuCdZnS, MnS, ZnMnS, ZnPbS, WS, ZnWS, CoS, ZnCoS, NiS, ZnNiS, InS, SnS, and ZnSnS.

[0031] In another aspect of the present invention, a light-emitting device is provided, comprising a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the above-mentioned quantum dot material.

[0032] The quantum dot material provided by the present invention can be used as a quantum dot light-emitting layer material for a quantum dot light-emitting device, thereby enhancing the hole injection and transport capabilities of the quantum dot light-emitting layer and improving the carrier balance. At the same time, the ligand can be evenly dispersed in the quantum dot light-emitting layer, thereby avoiding adverse phenomena such as phase separation between materials, making the film layer uniform and stable, and thus improving the efficiency and lifespan of the device and other performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a quantum dot material according to an embodiment of the present invention;

[0034] Figure 2 A schematic structural diagram of a light emitting device according to an embodiment of the present invention;

[0035] Figure 3 FIG. 1 is a schematic structural diagram of a light emitting device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0036] In the embodiment of the present invention, the substituted or unsubstituted alkyl group (alkyl chain) may be a straight chain alkyl group (normal alkyl group) without branches, or an isomeric alkyl group with branches; for example, an alkyl group with 1-40 carbon atoms, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 carbon atoms, for example, methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl or isobutyl), pentyl (n-pentyl or isopentyl), hexyl (n-hexyl or isohexyl), heptyl (n-heptyl or isoheptyl), etc.

[0037] In addition, the substituted or unsubstituted aryl / aromatic ring can be selected from C6-C60 aryl (i.e., the number of carbon atoms is 6-60), specifically, it can be selected from monocyclic aryl or condensed ring aryl. The monocyclic aryl refers to a single phenyl or biphenyl group (i.e., the group contains at least one phenyl group, and when it contains at least two phenyl groups, the phenyl groups are connected by a single bond), for example, including phenyl, biphenyl, terphenyl, etc.; the condensed ring aryl refers to a group containing at least two aromatic rings, and at least two aromatic rings are connected in a ring (i.e., they are fused to each other by sharing two adjacent carbon atoms), for example, including naphthyl, anthracenyl, phenanthrenyl, indenyl, fluorenyl, etc.

[0038] In addition, the heteroaryl group / heteroaromatic ring can be selected from C3 to C60 heteroaryl groups, specifically including monocyclic heteroaryl groups or condensed-ring heteroaryl groups. The monocyclic heteroaryl group refers to a single heteroaryl group (aromatic heterocycle) or contains multiple aromatic groups, at least one of which is a heteroaryl group, and the remaining aromatic groups can be heteroaryl groups or aromatic groups, and any two of the multiple aromatic groups are connected by a single bond. Exemplarily, monocyclic heteroaryl groups include pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furanyl, thienyl, pyrrolyl, and the like; fused-ring heteroaryl groups refer to molecules containing at least two aromatic groups, at least two of which are connected in a ring (i.e., the two share two adjacent atoms and are fused to each other), and at least one aromatic group is a heteroaryl group. Exemplarily, for example, fused-ring heteroaryl groups can be selected from quinolyl, isoquinolyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothienyl, isobenzofuranyl, isobenzothienyl, indolyl, dibenzofuranyl, dibenzothienyl, carbazolyl, acridinyl, phenothiazinyl, phenoxazinyl, hydroacridinyl, and the like.

[0039] Quantum dot light-emitting diodes have the advantages of high color gamut, long potential life, good viewing angle, and low cost, and are very promising light-emitting devices. However, the efficiency and life of current light-emitting devices are poor and need to be improved. For example, due to the properties of the materials of each film layer in the quantum dot light-emitting device (QLED), hole injection in the quantum dot light-emitting layer is usually more difficult than electron injection, which affects the efficiency and life of the device. For example, in an organic-inorganic hybrid device, its hole transport layer (HTL) uses organic materials (such as TFB, etc.), while the electron transport layer (ETL) uses inorganic materials (such as ZnO, etc.). The conduction band of inorganic materials such as ZnO is deep, which is conducive to the injection of electrons, and ZnO as an inorganic substance has a higher mobility, which leads to more electrons and fewer holes in the quantum dot light-emitting layer, resulting in carrier imbalance in the quantum dot light-emitting layer, and then the efficiency and life of the device are poor. In addition, during the manufacturing or use of the device, phase separation and other phenomena are prone to occur between the materials in the quantum dot light-emitting layer, which is also an important factor affecting the performance of the device, such as efficiency and lifespan.

[0040] In view of the above problems, an embodiment of the present invention provides a quantum dot material, such as Figure 1 As shown, the quantum dot material includes quantum dots and ligands connected to the quantum dots through coordination bonds, and the ligands have a structure shown in the following formula 1:

[0041]

[0042] Wherein, D represents an electron donating group (electron donor); A represents a chain group; It represents a group containing N and a substituted or unsubstituted aromatic ring, wherein the substituent of the substituted aromatic ring is selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group.

[0043] Specifically, the ligand shown in Formula 1 contains an electron-donating group D, a chain group A, and a group containing N and an aromatic ring, which is conducive to the coordination of the ligand with the quantum dot, the modification of the quantum dot, and the improvement of the hole injection and transmission capabilities of the formed quantum dot material, thereby improving the carrier balance in the quantum dot light-emitting layer formed using the quantum dot material. In addition, the ligand is connected to the quantum dot through a coordination bond, so that the ligand can be evenly dispersed in the quantum dot light-emitting layer, avoiding undesirable phenomena such as phase separation between materials, thereby improving the efficiency and life of the device.

[0044] Generally, a quantum dot is connected to multiple ligands through coordination bonds, and the structure of the quantum dot material formed is as follows: Figure 1 As shown, it should be noted that Figure 1 It is shown that three ligands are connected to a quantum dot, but it is not limited to this. The number of ligands connected to a quantum dot is generally related to the structural size of the ligand. Relatively speaking, when the ligand structure is larger, the number of ligands connected to a quantum dot is smaller, and when the ligand structure is smaller, the number of ligands connected to a quantum dot is larger.

[0045] Specifically, D is an electron-donating group that can provide electrons to coordinate with the quantum dots (ie, connect with the quantum dots through a coordination bond), thereby connecting the ligand to the quantum dot material through a coordination bond.

[0046] Generally, the electron donating group D contains heteroatoms such as oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), etc., that is, D is selected from electron donors containing one or more of these heteroatoms.

[0047] In some specific embodiments, the electron donating group D can be selected from phosphorus-oxy Organophosphorus group Amino (-NH 2 ), carboxyl (-COOH), thiol (-SH), where R 9 , R 10 , R 11 , R 12 , R 13 Each is independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl.

[0048] Among them, when D is selected from amino, carboxyl, and thiol groups, it usually removes one H to coordinate with the quantum dots; when D is selected from phosphorus oxygen or organic phosphorus groups, it usually does not remove H, but coordinates with the quantum dots through lone electrons.

[0049] In addition, A represents a chain group, which generally includes a substituted or unsubstituted alkyl chain. The substituents of the substituted alkyl chain can be selected from electron-donating substituents and / or substituted or unsubstituted alkyl groups. The electron-donating substituents contain heteroatoms such as oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), etc., and can be specifically selected from phosphorus oxide groups, organic phosphorus groups, amino groups, carboxyl groups, and thiol groups. The substituents on the substituted alkyl chain can be one or more, and when there are multiple substituents, these substituents can be the same or different.

[0050] A (chain group) may contain one alkyl chain or multiple alkyl chains, and two adjacent alkyl chains are connected by a heteroatom, and the heteroatom is selected from O, N, S, P, etc. When the number of alkyl chains is greater than or equal to 3, the number of heteroatoms is greater than or equal to two, and these heteroatoms may be the same or different.

[0051] Specifically, A includes a segment having a structure shown in the following formula 1-A:

[0052]

[0053] Among them, R 3 , R 4 , R 5 , R 6 Each is independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, and electron-donating substituents containing heteroatoms; z is selected from O, S, -NR or R, R 7 , R 8 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; n 1 、n 2 are each independently 0 or a positive integer, and n 1 +n 2 ≥1, n 1 and n 2 Can be equal or unequal.

[0054] Specifically, There are n 1 R 3 and n 1 R 4 , when n 1 ≥2, these R 3 These R 4 Can be the same or different.

[0055] also, There are n 2 R 5 and n 2R 6 , when n 2 ≥2, these R 5 These R 6 Can be the same or different.

[0056] For example, when z is O, S or -NR, A may include multiple segments of formula 1-A, and accordingly, A includes multiple alkyl chains, and two adjacent alkyl chains are connected by a heteroatom in z (O, S or N in -NR).

[0057] For example, A can be a chain segment shown in Formula 1-A (the ligand correspondingly has a structure shown in Formula 1-1 below), when z is When A is an alkyl chain, when z is O, S or -NR, and n 1 、n 2 When both are not equal to 0, A contains two alkyl chains (i.e. ), the two alkyl chains are connected via a heteroatom in z (O, S or N in —NR).

[0058]

[0059] The presence of alkyl chains facilitates the coordination of ligands with quantum dots, improves the hole injection and transport capabilities of quantum dot materials, and can also increase the solubility of quantum dot materials in alkane solvents, thereby facilitating the use of orthogonal solvent processing methods to form quantum dot light-emitting layers and other film layers in the device, avoiding damage to the various film layers, thereby improving device preparation yield and performance.

[0060] Generally speaking, due to factors such as steric effects, the more carbon atoms there are in A, the more favorable it is for the ligand to coordinate to the quantum point. The number of carbon atoms in A can be greater than or equal to 2, preferably greater than or equal to 4.

[0061] For example, A is a segment of the structure shown in Formula 1-A, and z is The number of carbon atoms in A is equal to The sum of the number of carbon atoms in 3 , R 4 , R 5 , R 6 , R 7 , R 8 When each is independently H, n 1 +1+n 2 ≥2, preferably n 1 +1+n 2 ≥4.

[0062] Further research has shown that too many carbon atoms in A and too large a quantum dot material will also affect the mobility of holes to a certain extent. Therefore, it is generally preferred that the number of carbon atoms in A is less than or equal to 40.

[0063] Illustratively, the number of carbon atoms in A can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 25, 30, 35, 40, or a range between any two thereof.

[0064] also, It represents a group containing N and a substituted or unsubstituted aromatic ring, which can specifically represent an aromatic amine compound, that is, N and the aromatic ring are connected by a single bond, and the aromatic ring can be selected from an aromatic ring (such as a benzene ring) or a heteroaromatic ring.

[0065] Among them, when the substituent of the substituted aromatic ring is selected from a substituted or unsubstituted alkyl group, the carbon number of the substituted or unsubstituted alkyl group is greater than or equal to 3, preferably 3-10, such as 3, 4, 5, 6, 7, 8, 9 or 10. Controlling the alkyl chain length within such a range is beneficial to further improve the hole injection and transport capabilities of the quantum dot material, and improve the solubility of the quantum dot material in alkane solvents, which is convenient for preparing devices by orthogonal solvent processing and improving the preparation yield and performance of the device.

[0066] In addition, when the substituent of the substituted aromatic ring is a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl, the substituent of the substituted aryl and the substituent of the substituted heteroaryl can be independently selected from substituted or unsubstituted alkyl groups, and the number of carbon atoms in the substituted or unsubstituted alkyl group is greater than or equal to 3, preferably 3-10, such as 3, 4, 5, 6, 7, 8, 9 or 10. Controlling the alkyl chain length within such a range is beneficial to further improve the hole injection and transport capabilities of the quantum dot material, and improve the solubility of the quantum dot material in alkane solvents, so as to facilitate the preparation of devices by orthogonal solvent processing and improve the preparation yield and performance of the device.

[0067] In addition, when the substituent of the substituted aromatic ring is a substituted or unsubstituted heteroaryl group, the heteroatom in the heteroaryl group may be selected from one or more of O, S, and N.

[0068] In addition, when the substituent of the substituted aromatic ring is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group, the substituted or unsubstituted aryl group or the substituted or unsubstituted heteroaryl group can be connected to the aromatic ring by a single bond or by a ring connection (i.e., the two share two adjacent atoms).

[0069] also, The number of substituents on the aromatic ring in is less than or equal to 5, for example 1, 2, 3, 4 or 5, etc.

[0070] The number of aromatic rings in the formula may be one or more, for example, two, and N is connected to the aromatic rings by a single bond, generally connected to two aromatic rings, and N and the two aromatic rings may not form a ring (such as the following formula 1-N 1 ) or a ring, the ring formed is, for example, a five-membered ring (such as the following formula 1-N 2 )wait.

[0071] Specifically, It may have a structure as shown in the following formula 1-N:

[0072]

[0073] Among them, R 1 , R 2 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, R 14 , R 15 are each independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; R 1 , R 2 Each is independently connected to its respective benzene ring by a single bond or a ring; R 1 , R 2 Each independently represents a single substitution to the maximum permissible substituent, that is, in formula 1-N, R 1 The number of 2 The number of can be independently 1, 2, 3, 4 or 5 (when the dotted line indicates that the carbon atoms at both ends of the dotted line are connected to each other, R 1 The number of 2 The number of each is independently at most 4), when R 1 When the number is multiple, these R 1 Can be the same or different, when R 2 When the number is multiple, these R 2 Can be the same or different.

[0074] The dotted line in formula 1-N Indicates that the carbon atoms at both ends of the dotted line are connected to each other or not. Specifically, there are two benzene rings in formula 1-N, and the two benzene rings are connected to N through single bonds respectively. The two benzene rings may not be connected, that is, the carbon atoms at both ends of the above dotted line are not connected, and N and the two benzene rings do not form a ring; or, the two benzene rings are connected through the sites shown by the above dotted line, thereby forming a ring with N and the two benzene rings, for example, the two benzene rings are directly connected through a chemical bond, that is, the above dotted line represents a chemical bond, one end of which is connected to the adjacent carbon atom on one benzene ring, and the other end is connected to the adjacent carbon atom on the other benzene ring, and N and the two benzene rings form a five-membered ring; or the two benzene rings are connected through other groups, that is, the dotted line represents other groups, and N forms an m-membered ring (m>5 and m is an integer) after connecting with the two benzene rings and other groups.

[0075] Specifically, It can have the following formula 1-N 1 Or 1-N 2 The structure shown:

[0076]

[0077] In some specific embodiments, the ligand can be selected from ligands B1-B8 having the following structures:

[0078]

[0079]

[0080] The quantum dots in the quantum dot material can emit light under the excitation of an electric field. In some embodiments, such as Figure 1As shown, the quantum dots can have a core-shell structure, and the core of the core-shell structure can include one or more of CdSe, CdSeS, CdZnSe, CdZnSeS, CdS, CdZnS, InP, InZnP, InGaP, GaP, ZnTeSe, ZnSe, ZnTe, CuInS, CuInZnS, CuInZnSe, AgInZnSe, CuInSe, AgInSe, AgS, AgSe, AgSeS, PbS, PbSe, PbSeS, PbTe, HgS, HgSe, HgTe, CdHgTe, CgHgSe, CdHgS, CdTe, CdZnTe, CdTeSe, and CdTeS, and the shell can include ZnS, ZnSe, ZnSeS, ZnN, ZnS, AlSb, ZnP, InP, AlS, PbS, HgS, AgS, Zn InS, ZnAlS, ZnSeS, CdSeS, CuInS, CuGaS, CuAlS, AgInS, AgAlS, AgGaS, ZnInP, ZnGaP, CdZnS, CdPbS, CdHgS, PbHgS, CdZnPbS, CdZnHgS, CdInZnS, CdAlZnS, CdSeZnS, AgInZnS, CuInZnS, Ag One or more of GaZnS, CuGaZnS, CuZnSnS, CuAlZnS, CuCdZnS, MnS, ZnMnS, ZnPbS, WS, ZnWS, CoS, ZnCoS, NiS, ZnNiS, InS, SnS, and ZnSnS. This is more conducive to the coordination of the above-mentioned ligands with quantum dots, and improves the hole injection and transmission capabilities of the quantum dot materials, further improving the efficiency and other performance of the device.

[0081] In some embodiments, the preparation process of the above-mentioned quantum dot material may include: mixing a first liquid containing a ligand with a second liquid containing quantum dots to allow the ligand to contact and react with the quantum dots, through which the ligand and the quantum dots are bonded through coordination bonds to obtain a quantum dot material.

[0082] Among them, the first liquid can be prepared by mixing the ligand and the first solvent, specifically a solution formed by dissolving the ligand in the first solvent. The first solvent used includes, but is not limited to, one or more of toluene, chlorobenzene, dichloromethane, chloroform, n-hexane, anisole, etc.

[0083] Among them, the second slurry can be prepared by mixing quantum dots with a second solvent, and the second solvent used includes, for example, but is not limited to, C6-C22 alkyl primary amines (such as hexadecylamine), C6-C22 alkyl secondary amines (such as dioctylamine), C6-C40 alkyl tertiary amines (such as trioctylamine), nitrogen-containing heterocyclic compounds (such as pyridine), C6-C40 olefins (such as octadecene), C6-C40 aliphatic hydrocarbons (such as hexadecane, octadecane or squalane), aromatic hydrocarbons substituted with C6-C30 alkyl groups (such as phenyldodecane, phenyltetradecane or phenylhexadecane), phosphines substituted with C6-C22 alkyl groups (such as trioctylphosphine), phosphine oxides substituted with C6-C22 alkyl groups (such as trioctylphosphine oxide), C12-C22 aromatic ethers (such as phenyl ether or benzyl ether), etc. One or more.

[0084] The light emitting device of the embodiment of the present invention is a quantum dot light emitting device (i.e., a quantum dot light emitting diode (QLED)). Figure 2 and Figure 3 As shown, the light-emitting device includes an anode, a hole transport region, a quantum dot light-emitting layer, an electron transport region and a cathode which are stacked in sequence, wherein the quantum dot light-emitting layer includes the above-mentioned quantum dot material, thereby improving the carrier balance in the quantum dot light-emitting layer and improving the efficiency, lifespan and other performance of the device.

[0085] The hole transport region may include a hole injection layer (HIL) and / or a hole transport layer (HTL). When the hole injection layer and the hole transport layer are included, the anode, the hole injection layer, the hole transport layer, and the quantum dot light-emitting layer are stacked in sequence.

[0086] For example, Figure 2 As shown, the hole transport region includes a hole transport layer; or, as shown Figure 3 As shown, the hole transport region includes a hole injection layer and a hole transport layer.

[0087] The electron transport region may include an electron injection layer (EIL) and / or an electron transport layer (ETL). When the electron injection layer and / or the electron transport layer are included, the quantum dot light emitting layer, the electron transport layer, the electron injection layer, and the cathode are stacked in sequence.

[0088] Unless otherwise specified, the materials of the above-mentioned layers may be conventional materials of these layers, and the materials used may be commercially available or prepared by conventional methods in the art.

[0089] Exemplarily, the anode includes indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO 2 ), zinc oxide (ZnO) and other oxide transparent conductive materials and any combination thereof.

[0090] Exemplarily, the cathode material includes at least one of metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag).

[0091] Exemplarily, the hole injection layer material includes, for example, PEDOT:PSS and the like.

[0092] In addition, the material of the hole transport layer includes an organic material, for example, 1,2,4,5-tetrakis(trifluoromethyl)benzene (TFB).

[0093] In addition, the material of the electron transport layer includes inorganic materials, such as ZnO and the like.

[0094] The above-mentioned light-emitting device can be prepared by conventional methods in the art. For example, the hole injection layer, hole transport layer, quantum dot light-emitting layer, electron transport layer and other film layers therein can be formed by coating (such as spin coating), evaporation, printing and the like.

[0095] Exemplarily, the preparation process of the light-emitting device may include: applying a third liquid containing a hole transport material on the anode to form a hole transport layer; applying a fourth liquid containing a quantum dot material on the hole transport layer to form a quantum dot light-emitting layer; and applying a fifth liquid containing an electron transport material on the quantum dot light-emitting layer to form an electron transport layer.

[0096] The third liquid containing the hole transport material is coated on the anode, and specifically can be directly coated on the anode to form a hole transport layer (the light-emitting device prepared at this time includes an anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, a cathode and other structures stacked in sequence (such as Figure 2 As shown), or coated on the hole injection layer of the anode having the hole injection layer, and forming the hole transport layer on the hole injection layer (the light-emitting device prepared in this case includes the anode, the hole injection layer, the hole transport layer, the quantum dot light-emitting layer, the electron transport layer, the cathode and other structures stacked in sequence (as shown) Figure 3 shown)).

[0097] Specifically, the third liquid may be made by mixing a hole transport material with a third solvent, the fourth liquid may be made by mixing a quantum dot material with a fourth solvent, and the fifth liquid may be made by mixing an electron transport material with a fifth solvent.

[0098] Among them, the third solvent and the fourth solvent are orthogonal solvents, that is, the hole transport material can be dissolved in the third solvent, but is basically insoluble in the fourth solvent. In this way, by forming each film layer through the orthogonal solvent processing method, it is possible to avoid damage to the hole transport layer when forming the quantum dot light-emitting layer.

[0099] In addition, the fourth solvent and the fifth solvent are orthogonal solvents, that is, the quantum dot luminescent material can be dissolved in the fourth solvent, but is basically insoluble in the fifth solvent. In this way, by forming each film layer through the orthogonal solvent processing method, damage to the quantum dot luminescent layer can be avoided when forming the electron transport layer.

[0100] Specifically, the third solvent may include an organic solvent, for example, chlorobenzene or the like.

[0101] Specifically, the fourth solvent may include an alkane solvent.

[0102] Specifically, the fifth solvent may include an alcohol solvent, such as ethanol.

[0103] The organic electroluminescent device of the present invention is further described below through specific embodiments.

[0104] Example 1

[0105] The device structure of this embodiment is as follows Figure 3 As shown, it includes an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a cathode stacked in sequence, wherein:

[0106] The anode material is TIO glass;

[0107] The hole injection layer material is PEDOT:PSS;

[0108] The hole transport layer material is TFB;

[0109] The quantum dots of quantum dot luminescent materials are core-shell structures, with CdSe as the core, ZnS as the shell, and B4 as the ligand;

[0110] The material of the electron transport layer is ZnO;

[0111] The material of the cathode is Ag.

[0112] Example 2 to Example 14: The only difference from Example 1 is that the ligands in the quantum dot materials are different, see Table 1 for details.

[0113] Comparative Example 1: The only difference from Example 1 is that there is no ligand on the quantum dots, that is, the quantum dot material used is a quantum dot with a core-shell structure in which the core is CdSe and the shell is ZnS.

[0114] Comparative Example 2: The only difference from Example 1 is that the ligand in the quantum dot material is propylamine

[0115] In addition, the efficiency and life of the devices of Examples 1 to 14 and Comparative Examples 1 to 2 were measured, and the measurement results are shown in Table 1. The efficiency and life test process is as follows:

[0116] 1. Lifespan: The lifespan test of LT95 is as follows: Use a luminance meter at 1000cd / m 2 At the same brightness, the current is kept constant and the brightness of the device is measured to be reduced to 950cd / m 2 The time, in hours (h);

[0117] 2. Efficiency: Under the same brightness, the current efficiency of the organic electroluminescent devices prepared in the examples and comparative examples was measured using a PR 750 photoradiometer from Photo Research, a ST-86LA luminance meter (from Beijing Normal University Photoelectric Instrument Factory) and a Keithley 4200 test system. Specifically, the voltage was increased at a rate of 0.1 V per second to measure the current efficiency of the organic electroluminescent device when the brightness reached 1000 cd / m 2 The current density at this time; at the same time, the external quantum efficiency (EQE) of the device at this time can be directly tested on PR650.

[0118] Table 1

[0119] Example Ligand efficiency life Example 1 B4 17.7％ 1513h Example 2 B1 13.2％ 478h Example 3 B9 10.1％ 372h Example 4 B10 17.4％ 1325h Example 5 B11 17.7％ 1091h Example 6 B7 17.1％ 5892h Example 7 B8 16.1％ 6942h Example 8 B6 17.2％ 1542h Example 9 B2 7.9％ 1293h Example 10 B5 6.9％ 1123h Embodiment 11 B3 8.3％ 892h Example 12 B12 9.8％ 902h Example 13 B13 15.4％ 1380h Embodiment 14 B14 15.2％ 1029h Comparative Example 1 / 1.3％ 1.7h Comparative Example 2 Propylamine 4.9％ 200h

[0120] It can be seen from Table 1 that, compared with Comparative Examples 1 and 2, the quantum dot materials formed by connecting the ligands shown in Formula 1 and quantum dots through coordination bonds in Examples 1 to 14 can significantly improve the efficiency and life of the device.

[0121] In addition, it can be seen from Examples 1 and 3 that in the ligand B4 used in Example 1, the number of carbon atoms in A of Formula 1 is greater (greater than 4), which can more significantly improve the performance of the light-emitting device, such as efficiency and lifespan.

[0122] In addition, it can be seen from Examples 1 and 4-5 that in the ligand B4 used in Example 1, The substituent (alkyl group) on the aromatic ring in the group containing N and an aromatic ring has a larger number of carbon atoms (equal to 3), which can more significantly improve the performance of the light-emitting device, such as the efficiency and life span.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quantum dot material, characterized in that: It includes quantum dots and ligands connected to the quantum dots through coordination bonds, The ligand is selected from ligands B1-B14 having the following structures:

2. The quantum dot material according to claim 1, characterized in that The quantum dots have a core-shell structure; The core of the core-shell structure comprises at least one of CdSe, CdSeS, CdZnSe, CdZnSeS, CdS, CdZnS, InP, InZnP, InGaP, GaP, ZnTeSe, ZnSe, ZnTe, CuInS, CuInZnS, CuInZnSe, AgInZnSe, CuInSe, AgInSe, AgS, AgSe, AgSeS, PbS, PbSe, PbSeS, PbTe, HgS, HgSe, HgTe, CdHgTe, CgHgSe, CdHgS, CdTe, CdZnTe, CdTeSe, and CdTeS; The shell of the core-shell structure comprises ZnS, ZnSe, ZnSeS, ZnN, ZnS, AlSb, ZnP, InP, AlS, PbS, HgS, AgS, ZnInS, ZnAlS, ZnSeS, CdSeS, CuInS, CuGaS, CuAlS, AgInS, AgAlS, AgGaS, ZnInP, ZnGaP, CdZnS, CdPbS, CdHgS, PbHgS, C dZnPbS, CdZnHgS, CdInZnS, CdAlZnS, CdSeZnS, AgInZnS, CuInZnS, AgGaZnS, CuGaZnS, CuZnSnS, At least one of CuAlZnS, CuCdZnS, MnS, ZnMnS, ZnPbS, WS, ZnWS, CoS, ZnCoS, NiS, ZnNiS, InS, SnS, and ZnSnS.

3. A light emitting device, characterized in that: It comprises a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the quantum dot material according to claim 1 or 2.

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