Ink and light emitting device

Abstract

The invention relates to ink and a light-emitting device. The ink comprises a solvent, and an organic luminescent material and a discotic liquid crystal material which are dispersed in the solvent. According to the ink, the wettability of the ink on the surface of a substrate can be improved by adding the discotic liquid crystal material, the substrate can be more uniformly coated with the ink, the uniformity of a thin film is enhanced, and the discotic liquid crystal material has self-assembly capacity and can promote molecular arrangement and accumulation in the thin film forming process, so that the compactness and quality of the thin film are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light-emitting devices, in particular to an ink and a light-emitting device. BACKGROUND

[0002] With the development of electronic display technology, organic electroluminescence diode (OLED) has been widely used in household electronic devices, large display devices and other fields. Compared with other traditional display technologies, OLED has obvious advantages in energy saving effect and the like.

[0003] At present, the preparation methods of OLED mainly include vacuum evaporation method and solution processing method. The vacuum evaporation method can prepare devices with complex structure and excellent performance, however, due to the need for high vacuum and high temperature process conditions, the preparation efficiency of this method is low, and it is easy to be affected by material pollution. Compared with the vacuum evaporation method, the solution processing method can effectively reduce the complexity and cost of preparation, and through the inkjet printing technology, the preparation of large-area multi-color display can be realized, and the spin coating method for preparing OLED can realize large-scale batch production and precise control of doping ratio.

[0004] In the preparation process of OLED device, the density difference between different film layers is an important problem. The solution processing method usually uses a solution in an organic solvent to prepare a thin film, and the vacuum deposition method uses a physical vapor deposition technology to prepare a thin film in a vacuum environment. Due to the volatility of the solvent and the organic material used in the solution method, and the difference in flowability in the processing process, the film densification of the solution method is usually lower than that of the vacuum deposition method. When the light-emitting layer is prepared by the solution method, the performance of the OLED device is poor when the functional layer adjacent to the light-emitting layer, such as the hole transport layer and the electron transport layer, is prepared by the vacuum deposition method. One of the reasons is that there is a large difference in densification between the film formation of the solution method and the film formation of the vacuum deposition method, which reduces the performance of the device. SUMMARY

[0005] Therefore, it is necessary to provide an ink and a light-emitting device to improve the performance of the device.

[0006] The first aspect of the present application provides an ink, and the scheme is as follows:

[0007] An ink, comprising a solvent, an organic light-emitting material and a discotic liquid crystal material, the organic light-emitting material and the discotic liquid crystal material being dispersed in the solvent.

[0008] The second aspect of the present application provides a light-emitting device, and the scheme is as follows:

[0009] The application discloses a light-emitting device, which comprises a substrate, a first electrode layer, a light-emitting layer and a second electrode layer arranged in a stack, wherein the light-emitting layer comprises an organic light-emitting material and a discotic liquid crystal material, and the mass ratio of the organic light-emitting material to the discotic liquid crystal material is (95-99):(1-5).

[0010] Compared with the conventional scheme, the above-mentioned ink and light-emitting device have the following beneficial effects:

[0011] The above-mentioned ink can improve the wettability of the ink on the surface of a substrate, so that the ink is more uniformly coated on the substrate, and the uniformity of the thin film is enhanced. In addition, the discotic liquid crystal material has a self-assembly ability, which can promote the molecular arrangement and accumulation during the thin film formation, thereby improving the compactness and quality of the thin film. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 FIG. 1 is a schematic structural diagram of a light-emitting device according to an embodiment of the application;

[0013] Figure 2 FIG. 6 is a schematic diagram of the current efficiency-current density of the light-emitting device prepared in Examples 1-24 and Comparative Example 1. DETAILED DESCRIPTION

[0014] In order to make the above objectives, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the application. However, the application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the application, so the application is not limited to the specific embodiments disclosed below.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0016] In the description of the application, it is to be understood by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0017] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0018] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0019] In the present application, halogen can be selected from one or more of F, Cl, Br, I. "Alkyl" can mean straight chain, branched chain and / or cyclic alkyl. The phrase including this term, for example, "C1-C12 alkyl" means alkyl groups containing 1 to 12 carbon atoms, each occurrence of which can be independently of one another C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, C10 alkyl, C11 alkyl, C12 alkyl. Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, isobutyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, t-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, t-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, cyclooctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldodecyl, 2-octyldodecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldodecyl, 2-octyldodecyl.

[0020] In the present application, an aromatic group means a hydrocarbon group or a fused ring aromatic group comprising at least one aromatic ring. A heteroaromatic group means an aromatic hydrocarbon group or a fused heteroaromatic group comprising at least one heteroatom. The heteroatom is preferably selected from Si, N, P, O, S and / or Ge, particularly preferably selected from Si, N, P, O and / or S. A fused ring aromatic group means that the ring of the aromatic group can have two or more rings, in which two carbon atoms are shared by two adjacent rings, i.e. a fused ring. A fused heteroaromatic group means a fused ring aromatic hydrocarbon group comprising at least one heteroatom. For the purpose of the present application, an aromatic group or a heteroaromatic group includes not only a system of aromatic rings, but also a non-aromatic ring system.

[0021] For the purpose of the present application, a fused ring aromatic or a fused heteroaromatic ring system includes not only a system of aromatic groups or heteroaromatic groups. In the present application, the "number of ring atoms" means the number of atoms constituting the ring itself in a structural compound obtained by bonding atoms into a ring (e.g., monocyclic compounds, fused ring compounds, crosslinked compounds, carbocyclic compounds, heterocyclic compounds), i.e., the number of atoms forming a ring. When the ring is substituted with a substituent, the atoms included in the substituent are not included in the ring atoms. The same applies to the "number of ring atoms" described below, unless otherwise specified. For example, the number of ring atoms of a benzene ring is 6, the number of ring atoms of a naphthalene ring is 10, and the number of ring atoms of a thiophene group is 5.

[0022] "Alkoxy" refers to a group of the structure "-O-alkyl", i.e., an alkyl group as defined above attached via an oxygen atom to the remainder of the molecule. Suitable examples of phrases containing this term include, but are not limited to: methoxy (-O-CH3or -OMe), ethoxy (-O-CH2CH3or -OEt), t-butoxy (-O-C(CH3)3or -OTBu), n-hexyloxy (-O-C6H 13 ), n-decyloxy (-O-C 10 H 21 ), n-dodecyloxy (-O-C 12 H 25 ).

[0023] In the present application, "aryloxy" refers to a group of the structure "-O-aryl", i.e., an aryl group as defined above attached via an oxygen atom to the remainder of the molecule. Suitable examples of phrases containing this term include, but are not limited to: phenoxy, naphthoxy, and the like. "Heteroaryloxy" refers to a group of the structure "-O-heteroaryl", i.e., a heteroaryl group as defined above attached via an oxygen atom to the remainder of the molecule. "Alkoxyaryl" refers to a group of the structure "-aryl-alkoxy", i.e., an alkoxy group as defined above attached via an aryl group to the remainder of the molecule, for example, hexyloxyphenyl represents -ph-OC6H 13 where ph refers to phenyl.

[0024] In the present application, "alkylthio" refers to a group of the structure "-S-alkyl", i.e., an alkyl group as defined above attached via a sulfur atom to the remainder of the molecule. Suitable examples of phrases containing this term include, but are not limited to: methylthio (-S-CH3or -SMe), ethylthio (-S-CH2CH3or -SEt), t-butylthio (-S-C(CH3)3or -StBu), n-hexylthio (-S-C6H 13 ), n-decylthio (-S-C 10 H 21 ), n-dodecylthio (-S-C 12 H 25 ). Similarly, "arylthio" refers to a group of the structure "-S-aryl", and "heteroarylthio" refers to a group of the structure "-S-heteroaryl".

[0025] In the present application, amino represents -NR1R2, where each R1, R2independently represents H or alkyl, i.e., amino can represent -NH2, -NH(alkyl), or -Nalkyl(alkyl).

[0026] In the present application, "arylaminos" refer to groups of the structure "-NR-aryl" or "-Naryl(aryl)", i.e., an aryl group as defined above attached via an N atom to the remainder of the molecule, for example "Alkylamino" refers to a group of the structure "-NR-alkyl" wherein R is alkyl as defined above. "Amino" refers to a group of the structure "-NH2".

[0027] In the present application, "a'' connected to a single bond" indicates a connection site or a fused site. When the connection site in a group is not specified, it indicates that an optional connection site in the group can be used as the connection site. For example, In the above formula (1), any optional connection site on the two benzene rings and the optional connection site on Z can be used as the connection site in the main skeleton structure; it can be understood that when Z is used as the optional connection site, Z is N.

[0028] In the present application, a single bond connecting a substituent group is throughout the corresponding ring, indicating that the substituent group can be connected to an optional position of the ring. For example In the above formula (1), R 13 may be connected to any optional substitutable site in the benzene ring.

[0029] In the present application, "combinations thereof", "any combination thereof", "any combination manner thereof" and the like include all suitable combination manners of any two or more items in the listed items.

[0030] The present application provides an ink.

[0031] An embodiment includes a solvent, an organic light-emitting material, and a discotic liquid crystal material, wherein the organic light-emitting material and the discotic liquid crystal material are dispersed in the solvent.

[0032] The above ink can improve the wettability of the ink on the surface of a substrate by adding a discotic liquid crystal material, so that the ink is more uniformly coated on the substrate, the uniformity of the thin film is enhanced, and the discotic liquid crystal material has a self-assembly ability, which can promote the molecular arrangement and accumulation during the formation of the thin film, thereby improving the density and quality of the thin film.

[0033] The mass ratio of the organic light-emitting material to the discotic liquid crystal material is (95-99):(1-5). In some examples, the mass ratio of the organic light-emitting material to the discotic liquid crystal material is (95-97):(3-5). In some examples, the mass ratio of the organic light-emitting material to the discotic liquid crystal material is (96-97):(3-4).

[0034] In some examples, the discotic liquid crystal material is selected from at least one of the compounds having the structures shown in formula (1) to formula (2).

[0035]

[0036] In formula (1), R61, R62, R63, R64are independently selected from a halogen atom, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 alkoxy group. n1, n2, n3, n4are independently any integer from 0 to 4.

[0037] Further, R61, R62, R63, R64are preferably flexible chains, such structures have the molecules to easily form columnar liquid crystal phase. For example, R61, R62, R63, R64are independently selected from a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C2-C12 alkoxy group.

[0038] When substituted by a substituent, each occurrence of the substituent is independently selected from an amino group, a halogen, a hydroxyl group, a carboxyl group, a nitro group, a sulfonic acid group, a mercapto group, a cyano group, a C1-C12 alkyl group.

[0039] In formula (2), R71, R72, R73are independently selected from a halogen atom, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C1-C12 alkoxy group. n5, n6, n7are independently any integer from 0 to 4.

[0040] Further, R71, R72, R73are preferably flexible chains, such structures have the molecules to easily form columnar liquid crystal phase. For example, R71, R72, R73are independently selected from a substituted or unsubstituted C2-C12 alkyl group, a substituted or unsubstituted C2-C12 alkoxy group.

[0041] When substituted by a substituent, each occurrence of the substituent is independently selected from an amino group, a halogen, a hydroxyl group, a carboxyl group, a nitro group, a sulfonic acid group, a mercapto group, a cyano group, a C1-C12 alkyl group.

[0042] The discotic liquid crystal material comprises an aromatic hydrocarbon core and peripheral groups attached to the aromatic hydrocarbon core. The discotic liquid crystal material is capable of self-assembly into a fibrous network in a specific solvent, resulting in the formation of a physical (non-covalently bonded) gel. The self-assembly of fibers in the discotic liquid crystal material is a process driven by the fine interactions of attractive intermolecular forces between the π-stacked molecules.

[0043] The discotic liquid crystal material is advantageous in improving the wettability of the ink on the surface of the substrate, allowing the ink to be more uniformly coated on the substrate, thereby reducing the thickness and gradient difference of the composition of the film, and improving the uniformity of the film. The uniform thin film can improve the light-emitting efficiency, color uniformity and long-term stability of the device, thereby improving the brightness, color quality and life of the device.

[0044] Further, the discotic liquid crystal material is selected from at least one of the compounds having the structures shown in formula (3) to formula (4).

[0045]

[0046] In some examples, the organic light emitting material includes one or more of the following compounds having the general formula:

[0047]

[0048] wherein R3, R4, and R7are each independently selected from one or more of the following: a substituted or unsubstituted C 6-60 an aryl group, a substituted or unsubstituted heteroaryl group having 5 to 60 ring atoms, a substituted or unsubstituted arylamino group having 6 to 60 ring atoms, a substituted or unsubstituted aryloxy group having 6 to 60 ring atoms, a substituted or unsubstituted arylmercapto group having 6 to 60 ring atoms, a substituted or unsubstituted heteroarylamino group having 5 to 60 ring atoms, a substituted or unsubstituted heteroaryloxy group having 5 to 60 ring atoms, and a substituted or unsubstituted heteroarylmercapto group having 5 to 60 ring atoms;

[0049] the substituents of R3, R4, and R7, at each occurrence, are each independently selected from one or more of the following: D, halogen, cyano, amino, nitro, mercapto, carbonyl, C1-C20alkyl, C1-C20alkenyl, C1-C20alkoxy, a heteroaryl group having 5 to 30 ring atoms, and a C6-C30aryl group;

[0050] the heteroatoms in the heteroaryl group, the heteroaryloxy group, the heteroarylamino group, and the heteroarylmercapto group are each independently selected from one or more of the following: O, P, N, and S;

[0051] R1, R2, R5, and R6are each independently selected from one or more of the following: H, D, halogen, cyano, amino, nitro, C1-C20alkyl, C1-C20alkoxy, a heteroaryl group having 5 to 20 ring atoms, and a C6-C20aryl group;

[0052] In some examples, the organic light emitting material includes one or more of the following compounds having the general formula:

[0053]

[0054] wherein R8is selected from one or more of the following: H, D, halogen, cyano, amino, nitro, C1-C14alkyl, C1-C14alkoxy, a heteroaryl group having 5 to 14 ring atoms, and a C6-C14aryl group;

[0055] R9and R 11 are each independently selected from a C6-C30aryl group;

[0056] R 10 and R 12each independently selected from one of the following structures:

[0057]

[0058] wherein the connection site is *.

[0059] Z is -N, -CR 26 , -NR 27 , O, or S.

[0060] X is -N, -NR 28 , -CR 29 , CR 30 R 31 , S, or O.

[0061] R 13 ~ R 25 each independently selected from one or more of H, D, halogen, cyano, amino, nitro, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthiol, and substituted or unsubstituted C1-C30 alkylamino.

[0062] R 26 , R 27 , R 28 , R 29 , R 30 , R 31 each independently selected from one or more of H, D, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthiol, substituted or unsubstituted C1-C30 alkylamino, and substituted or unsubstituted aryl having a ring atom number of C1-C30.

[0063] R 13 ~ R 31 substituted with one or more of D, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, thiol, cyano, carbonyl, C1-C20 alkyl, C1-C20 alkenyl, C1-C20 alkoxy, heteroaryl having a ring atom number of 5-20, and C6-C20 aryl, each occurrence is independently selected.

[0064] In some examples, R 10 and R 12 are each independently selected from one of the following groups:

[0065]

[0066] wherein R 32 ~ R 51one or more of H, D, halogen, cyano, amino, nitro, C1-C20 alkyl, C1-C20 alkoxy, heteroaryl having 5 to 20 ring atoms, and C6-C20 aryl.

[0067] In some examples, R9and R 11 each is independently selected from one of the following groups:

[0068]

[0069] In some examples, R9and R 11 each is independently selected from one of the following groups:

[0070]

[0071] In some examples, R 10 and R 12 each is independently selected from one of the following groups:

[0072]

[0073] The organic light-emitting material is at least one of the compounds shown in the following structural formula:

[0074]

[0075]

[0076]

[0077] Optionally, the solvent can be, but is not limited to, one or more of a hydrocarbon solvent, a halogenated hydrocarbon solvent, an ester solvent, and an aldehyde solvent.

[0078] For example, the solvent can be, but is not limited to, one or more of chloroform, toluene, xylene, chlorobenzene, methyl benzoate, formaldehyde, acetaldehyde, and benzaldehyde.

[0079] The ink has the following beneficial effects:

[0080] The ink adds the discotic liquid crystal material, which can promote the arrangement and accumulation of solute molecules in the ink, increase the interaction force between the molecules, reduce the pores and defects in the film formation, and is beneficial to improve the density and compactness of the film formation, thereby reducing the density difference between the film formation by the solution method and the film formation by the vacuum deposition method such as evaporation, and improving the performance and stability of the prepared light-emitting device.

[0081] The ink added discotic liquid crystal material is beneficial to improve the wettability of the ink on the surface of the substrate, so that the ink can be more uniformly coated on the substrate, thereby reducing the thickness and composition gradient difference of the film, and improving the uniformity of the film. Uniform thin film can improve the luminous efficiency, color uniformity and long-term stability of the device, thereby improving the brightness, color quality and life of the device.

[0082] The ink added discotic liquid crystal material can improve the wettability and flowability in the solution processing process, thereby increasing the fault tolerance and stability of the process, so that the preparation process is more easily controlled, and a larger process window is provided, so that the conditions for preparing high-quality thin films are more relaxed and flexible.

[0083] In summary, adding discotic liquid crystal material to the ink can improve the uniformity and density of the thin film, improve the performance and stability of the device, and expand the window of the preparation process, thereby bringing significant beneficial effects in the preparation process of light-emitting devices such as OLEDs.

[0084] Further, the present application also provides a light-emitting device.

[0085] The light-emitting device of an embodiment includes a substrate, a first electrode layer, a light-emitting layer, and a second electrode layer which are sequentially stacked, the light-emitting layer includes an organic light-emitting material and a discotic liquid crystal material, and the mass ratio of the organic light-emitting material to the discotic liquid crystal material is (95-99):(1-5).

[0086] In some examples, the thickness of the light-emitting layer is 20-40 nm, and is specifically, for example, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0087] It can be understood that a carrier functional layer can also be provided between the first electrode layer and the light-emitting layer and / or between the light-emitting layer and the second electrode layer. The carrier functional layer is, for example, one or more of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

[0088] Figure 1 The structure of the light-emitting device of an embodiment is shown. The light-emitting device 100 includes a substrate 110, a first electrode layer 120, a hole injection layer 130, a hole transport layer 140, a light-emitting layer 150, an electron transport layer 160, an electron injection layer 170, and a second electrode layer 180 which are sequentially stacked.

[0089] The light-emitting layer 150 contains an organic light-emitting material and a surfactant, as described above.

[0090] The material of the hole injection layer 130 is a material with hole injection capability, selected from one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), PEDOT:PSS / PFI mixture, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN), copper phthalocyanine (CuPc), transition metal oxide, transition metal chalcogenide; wherein the transition metal oxide includes one or more of NiO, M0O2, WO3, CuO; the metal chalcogenide includes one or more of M0S2, M0Se2, WS3, WSe3, CuS.

[0091] PEDOT:PSS, PEDOT:PSS / PFI mixture is a high transparency material, which can improve the light extraction efficiency of the device compared with HATCN. The PEDOT:PSS / PFI mixture is a mixture of perfluorinated ionomer PFI and PEDOT:PSS to modify PEDOT:PSS into a self-organizing gradient hole injection layer (GradHIL), for example, the mass ratio of PFI to PEDOT:PSS is (1-5): 1. The driving force of the self-organizing behavior comes from the stronger hydrophobicity of the fluorocarbon chain in PFI, which makes it preferentially stay on the surface of the film. Since PFI with fluorocarbon chain is more hydrophobic than polystyrene chain, PFI tends to stay away from the bottom electrode and form a "self-organizing" gradient, thus presenting a work function gradient in the hole injection layer. In addition to reducing the injection barrier, the PEDOT:PSS / PFI mixture can also inhibit the diffusion of indium and tin. Moreover, PFI has high transparency, and compounding with PEDOT:PSS can improve the light transmittance and reduce the light loss caused by the absorption of PEDOT:PSS. For example, pure PEDOT:PSS has a light transmittance of 90%-94% in the entire visible light range. When PFI is mixed with PEDOT:PSS at a mass ratio of 5:1, the light transmittance is further improved to 95%-98% due to the high transparency of PFI.

[0092] The material of the hole transport layer 140 is a material with hole transport capability, selected from one or more of polymer hole transport material and small molecule hole transport material.

[0093] Specifically, the polymer hole transport material includes but is not limited to one or more of poly(N-vinylcarbazole) (PVK), poly[bis(4-phenyl)(4-butylphenyl)amine] (poly-TPD), and poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)] (TFB).

[0094] Specifically, the small molecule hole transport material includes, but is not limited to, one or more of 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC), and 4,4'-bis(9-carbazol) biphenyl (CBP). In some examples, the material of the hole transport layer 140 is PVK, which has an advantage of good film-forming property compared to other small molecules mentioned above, and is more suitable for spin coating.

[0095] The material of the electron transport layer 160 is a material known in the art for an electron transport layer. For example, it can be selected from one or more of a doped or non-doped inorganic nanocrystal, an organic material; wherein the non-doped inorganic nanocrystal is selected from one or more of ZnO, TiO2, SnO2, Al2O3, GaO, Ga2O3, ZrO2, Fe2O3, CrO3, WO3, CdO, CuO, MoO2, ZnS, ZnSe, CdS, InP, GaP, SnO2, WO3, Ta2O3, HfO3, ZrSiO4, BaTiO3, BaZrO3, Si3N4; the doped inorganic nanocrystal includes the non-doped inorganic nanocrystal and a doping element, the doping element is selected from one or more of Mg, Ca, LiF, Ga, Al, Co, In, Mn, Cd, Cs, or Cu; the organic material is selected from one or more of 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine (B3PYMPM), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI), 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene (TmPyPB), 1,3-bis(3,5-dipyridyl-3-ylphenyl)benzene (B3PyPB), bis[2-(2-pyridyl)phenol]beryllium (Bepp2), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), tris-(8-hydroxyquinoline) aluminum (Alq3), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen), 2,7-bis(diphenylphosphine oxide)-9,9'-spirobi[fluorene] (SPPO13), diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide (TSPO1), 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole (PBD).

[0096] The material of the electron injection layer 170 can be, but is not limited to, one or more of LiF, NaF, CsF. The halide mentioned above can form a double electrode with the metal cathode, reduce the potential barrier of electron injection, and improve the luminous efficiency.

[0097] In some examples, the material of the electron injection layer 170 is LiF, which has a higher light transmittance and a lower refractive index, and is beneficial to improve the light extraction efficiency of the device. Although NaF and CsF have a lower work function, they have a higher refractive index, resulting in light reflection loss. Therefore, using LiF as the electron injection layer can improve the efficiency and stability of the device.

[0098] The first electrode layer 120 is an anode layer, and the second electrode layer 180 is a cathode layer.

[0099] The anode layer and the cathode layer are each independently selected from one or more of a metal electrode, a carbon electrode, a doped or undoped metal oxide electrode, and a composite electrode; wherein the material of the metal electrode is selected from one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg; the material of the carbon electrode is selected from one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the material of the doped or undoped metal oxide electrode is selected from one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO; and the material of the composite electrode is selected from one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. Herein, " / " represents a stacked structure, for example, the composite electrode AZO / Ag / AZO represents a composite structure electrode composed of three layers of AZO layer, Ag layer, and AZO layer stacked.

[0100] In some examples, the cathode material is aluminum, which has a higher reflectivity and can improve the light extraction efficiency of the device. Although magnesium and calcium have a lower work function, they are more easily oxidized, resulting in a decrease in device performance. Therefore, using aluminum as the cathode material can improve the stability and efficiency of the device. The anode material can be selected from indium tin oxide (ITO), transparent polymers, and metals, etc.

[0101] Further, the present application also provides a preparation method of the light-emitting device of any of the above examples.

[0102] A preparation method of a light-emitting device of an embodiment includes the following steps:

[0103] Providing a substrate provided with a first electrode layer;

[0104] Providing the ink of any of the above examples on the substrate, and drying to form a light-emitting layer;

[0105] Forming a second electrode layer on the light-emitting layer.

[0106] The light-emitting layer can be formed by depositing the ink and drying it. The light-emitting device can be prepared by using the ink and drying it to form the light-emitting layer, thereby achieving the corresponding technical effects.

[0107] The solution processing method can be, for example, spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spray coating, roll coating, casting, slot coating, and stripe coating.

[0108] The light-emitting device can be prepared by using the ink and drying it to form the light-emitting layer, thereby achieving the corresponding technical effects.

[0109] Further, the present application also provides a display device comprising the light-emitting device 100.

[0110] The display device comprises the light-emitting device, thereby achieving the corresponding technical effects.

[0111] The display device can be any electronic product with display function, including but not limited to a smartphone, a tablet computer, a notebook computer, a digital camera, a digital camcorder, a smart wearable device, a smart electronic scale, a car display, a television, or an e-book reader. The smart wearable device can be, for example, a smart bracelet, a smart watch, a virtual reality (VR) helmet, or the like.

[0112] The following specific embodiments are provided to further illustrate the present application. The present application provides the following specific embodiments to better further understand the present application, and is not limited to the best embodiments, and does not limit the content and protection scope of the present application. Any product or method obtained by combining the present application with other prior art features, or any product or method obtained by combining the present application with other prior art features, is within the scope of protection of the present application.

[0113] The structures of the discotic liquid crystal materials M1-M3 used in the following examples are shown in the above formula (4), wherein R71, R72, and R73 are the same group. In M1, R71, R72, and R73 are all F atoms. In M2, R71, R72, and R73 are all: In M3, R71, R72, and R73 are all:

[0114]

[0115] The structures of the discotic liquid crystal materials M4 to M8 used in the following examples are shown in the above formula (3), and R61, R62, R63, and R64 in formula (4) are the same group. In M4, R61, R62, R63, and R64 are all In M5, R61, R62, R63, and R64 are all In M6, R61, R62, R63, and R64 are all In M7, R61, R62, R63, and R64 are all In M8, R61, R62, R63, and R64 are all

[0116]

[0117] Example 1

[0118] The present embodiment provides a light-emitting device. The method for preparing the light-emitting device of the present embodiment comprises the following steps:

[0119] Step 1, a substrate is provided, which has a transparent conductive film ITO as an anode on the substrate, and the thickness of the ITO is 50 nm.

[0120] Step 2, a solution method is used to deposit PEDOT:PSS on the anode as a hole injection layer, and the thickness of the PEDOT:PSS is 30 nm.

[0121] Step 3, a solution method is used to deposit PVK on the hole injection layer as a hole transport layer, and the thickness of the PVK is 20 nm.

[0122] Step 4, a solution method is used to deposit a light-emitting layer on the hole transport layer, and the light-emitting layer material comprises a light-emitting material PAC and a discotic liquid crystal material M1, the mass ratio of PAC to M1 is 99:1, the solvent is chloroform, the total concentration of the light-emitting layer material is 6 mg / ml, the spin-coating speed and the spin-coating time are 1000 rpm and 30 s, the baking temperature and the baking time are 60°C and 15 mins, and the thickness of the light-emitting layer is 35 nm.

[0123] Step 5, a vapor deposition method is used to deposit SPPO13 on the light-emitting layer as an electron transport layer, and the thickness of the SPPO13 is 30 nm.

[0124] Step 6, a vapor deposition method is used to deposit LiF on the electron transport layer as an electron injection layer, and the thickness of the LiF is 100 nm.

[0125] Step 7, a vapor deposition method is used to deposit Al on the electron injection layer as a cathode, and the thickness of the Al is 100 nm.

[0126] Example 2: The present embodiment is basically the same as Example 1, except that the mass ratio of PAC to M1 is 97:3.

[0127] Example 3: This example is essentially the same as Example 2, except that the mass ratio of PAC to Ml is 95:5.

[0128] Example 4: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M2.

[0129] Example 5: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M3.

[0130] Example 6: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M4.

[0131] Example 7: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M5.

[0132] Example 8: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M6.

[0133] Example 9: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M7.

[0134] Example 10: This example is essentially the same as Example 2, except that the discotic liquid crystal material Ml in Step 4 is replaced by M8.

[0135] Example 11: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by PABPP.

[0136] Example 12: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by PATPA.

[0137] Example 13: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by mPAC.

[0138] Example 14: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by TPA-PPI.

[0139] Example 15: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by TBPMCN.

[0140] Example 16: This example is essentially the same as Example 2, except that the light emitting material PAC in Step 4 is replaced by TPMCN.

[0141] Example 17: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by TPINCz.

[0142] Example 18: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by 2FPPITPA.

[0143] Example 19: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by BITPI.

[0144] Example 20: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by DPACPhTPI.

[0145] Example 21: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by CPBPMCN.

[0146] Example 22: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by PPCTPI.

[0147] Example 23: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by CPPCN.

[0148] Example 24: This example is essentially the same as Example 2 except that the light-emitting material PAC in Step 4 is replaced by PAIDO.

[0149] Comparative Example 1: This comparative example is essentially the same as Example 1 except that no discotic liquid crystal material Ml is added in Step 4.

[0150] The light-emitting devices prepared in the above examples and comparative example were subjected to performance tests, and the test results are shown in Table 1 and Figure 2

[0151] Table 1 Performance test results of the light-emitting devices prepared in the examples and comparative example

[0152]

[0153]

[0154] In Table 1, V@1cd / m 2 indicates the driving voltage corresponding to a luminance of 1 cd / m 2

[0155] EQE max indicates the maximum EQE when measuring the IVL curve;

[0156] ​​T 95 (h)@1000cd / m 2 The device is continuously turned on at an initial luminance of 1000cd / m 2 When the luminance decays to 95% of the initial luminance (950cd / m 2 ), the time experienced is recorded.

[0157] The luminescent devices of the above-mentioned Examples 1-24 adopt the discotic liquid crystal material doped luminescent layer, while the luminescent layer of Comparative Example 1 is not doped with discotic liquid crystal material. As can be seen from the results in Table 2, compared with Comparative Example 1, the driving voltage of the luminescent devices prepared in Examples 1-24 is reduced, and the external quantum efficiency EQE and the device lifetime are obviously improved.

[0158] Figure 2 The current efficiency-current density diagram of the luminescent devices prepared in Examples 1-24 and Comparative Example 1. As can be seen from the diagram, Figure 2 the luminescent efficiency of the luminescent devices of Examples 1-24 is better than that of Comparative Example 1. Among them, when the mass ratio of the luminescent material and the discotic liquid crystal material is 95:5-97:3 (Examples 2, 3), the luminescent efficiency of the device is relatively high.

[0159] The technical features of the above-mentioned examples can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-mentioned examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0160] The above-mentioned examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. Ink, characterized in that, The solvent, the organic light-emitting material, and the discotic liquid crystal material are dispersed in the solvent.

2. The ink according to claim 1, wherein The discotic liquid crystal material is selected from at least one of compounds having structures represented by formula (1) to formula (2): In formula (1), R61, R62, R63, R64 are independently selected from halogen atom, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C1-C12 alkoxy, n1, n2, n3, n4 are independently any integer from 0 to 4; In formula (2), R71, R72, R73 are independently selected from halogen atom, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C1-C12 alkoxy, n5, n6, n7 are independently any integer from 0 to 4; When substituted, the substituent group in each occurrence is independently selected from amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid group, thiol, cyano, C1-C12 alkyl.

3. The ink according to claim 2, wherein The discotic liquid crystal material is selected from at least one of compounds having structures represented by formula (3) to formula (4):

4. The ink according to claim 2, wherein R61, R62, R63, R64 are independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkoxy; R71, R72, R73 are independently selected from substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C2-C12 alkoxy.

5. The ink according to any one of claims 1 to 4, wherein The organic light-emitting material comprises one or more of compounds having the following general formula: wherein R3, R4 and R7 are each independently selected from one or more of substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted heteroaryl with ring atoms number from 5 to 60, substituted or unsubstituted arylamino with ring atoms number from 6 to 60, substituted or unsubstituted aryloxy with ring atoms number from 6 to 60, substituted or unsubstituted arylthiol with ring atoms number from 6 to 60, substituted or unsubstituted heteroarylamino with ring atoms number from 5 to 60, substituted or unsubstituted heteroaryloxy with ring atoms number from 5 to 60, substituted or unsubstituted heteroarylthiol with ring atoms number from 5 to 60; the substituent group in each occurrence of R3, R4 and R7 is independently selected from one or more of D, halogen, cyano, amino, nitro, thiol, carbonyl, C1-C20 alkyl, C1-C20 alkenyl, C1-C20 alkoxy, heteroaryl with ring atoms number from 5 to 30, and C6-C30 aryl; the heteroatom in each of the heteroaryl, the heteroaryloxy, the heteroarylamino, the heteroarylthiol is independently selected from one or more of O, P, N, S; R1, R2, R5 and R6 are each independently selected from one or more of H, D, halogen, cyano, amino, nitro, C1-C20 alkyl, C1-C20 alkoxy, heteroaryl with ring atoms number from 5 to 20, and C6-C20 aryl.

6. The ink according to claim 5, characterized by The organic light-emitting material comprises one or more of compounds having the following general formula: R8is selected from one or more of H, D, halogen, cyano, amino, nitro, C1-C14alkyl, C1-C14alkoxy, heteroaryl having 5 to 14 ring atoms, and C6-C14aryl; R9and R 11 each independently is selected from C6-C30aryl; R 10 and R 12 are each independently selected from one of the following structures: wherein * is a linking site; Z is -N, -CR 26 , -NR 27 , O or S; X is -N, -NR 28 , -CR 29 , CR 30 R 31 , S or O; R 13 ~R 25 each independently selected from one or more of H, D, halogen, cyano, amino, nitro, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthio, substituted or unsubstituted C1-C30 alkylamino; R 26 , R 27 , R 28 , R 29 , R 30 , R 31 each independently is selected from one or more of H, D, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 alkylthiol, substituted or unsubstituted C1-C30 alkylamino, and substituted or unsubstituted aryl having a ring atom number of C1-C30; R 13 ~R 31 each of the substituents described in the substituent group is independently selected from one or more of D, amino, halogen, hydroxy, carboxy, nitro, sulfonic acid group, mercapto, cyano, carbonyl, C1-C20 alkyl, C1-C20 alkenyl, C1-C20 alkoxy, heteroaryl having 5 to 20 ring atoms, and C6-C20 aryl.

7. The ink according to claim 6, characterized by R 10 and R 12 are each independently selected from one of the following groups: wherein R 32 ~R 51 each independently is selected from one or more of H, D, halogen, cyano, amino, nitro, C1-C20alkyl, C1-C20alkoxy, heteroaryl having 5 to 20 ring atoms, and C6-C20aryl; and / or, R9and R 11 each independently is selected from one of the following groups:

8. The ink according to claim 6, characterized by R9and R 11 each independently is selected from one of the following groups: and / or, R 10 and R 12 each independently is selected from one of the following groups:

9. The ink according to claim 6, wherein the organic light-emitting material is at least one of the compounds represented by the following structural formula:

10. The ink according to any one of claims 1 to 4, 6 to 8, wherein the mass ratio of the organic light-emitting material to the discotic liquid crystal material is (95-99):(1-5); the concentration of the organic light-emitting material is 5 mg / ml to 15 mg / ml.

11. A light-emitting device, characterized in that, The organic light-emitting material and the discotic liquid crystal material are in a mass ratio of (95-99):(1-5).

12. The light emitting device of claim 11, wherein, The light-emitting device satisfies one or both of the following conditions: (1) the discotic liquid crystal material is selected from at least one of the compounds represented by the following formula (1) to (2): in formula (1), R61, R62, R63, R64are independently selected from halogen atom, substituted or unsubstituted C6-C20aryl, substituted or unsubstituted C1-C12alkyl, substituted or unsubstituted C1-C12alkoxy, n1, n2, n3, n4are independently any integer from 0 to 4; in formula (2), R71, R72, R73are independently selected from halogen atom, substituted or unsubstituted C6-C20aryl, substituted or unsubstituted C1-C12alkyl, substituted or unsubstituted C1-C12alkoxy, n5, n6, n7are independently any integer from 0 to 4; when substituted, each occurrence of the substituent is independently selected from amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid group, mercapto, cyano, C1-C12alkyl; (2) the organic light-emitting material comprises one or more of the compounds of the following general formula: wherein R3, R4and R7are each independently selected from one or more of substituted or unsubstituted C6-C60aryl, substituted or unsubstituted heteroaryl having 5 to 60 ring atoms, substituted or unsubstituted arylamino having 6 to 60 ring atoms, substituted or unsubstituted aryloxy having 6 to 60 ring atoms, substituted or unsubstituted arylmercapto having 6 to 60 ring atoms, substituted or unsubstituted heteroarylamino having 5 to 60 ring atoms, substituted or unsubstituted heteroaryloxy having 5 to 60 ring atoms, and substituted or unsubstituted heteroarylmercapto having 5 to 60 ring atoms; the substituents of the substitution in R3, R4and R7, each occurrence, are independently selected from the group consisting of D, halogen, cyano, amino, nitro, mercapto, carbonyl, C1-C20alkyl, C1-C20alkenyl, C1-C20alkoxy, heteroaryl having 5 to 30 ring atoms, and C6-C30aryl, in combination of one or more; the heteroatoms in the heteroaryl, the heteroaryloxy, the heteroarylamino, and the heteroarylmercapto are each independently selected from one or more of O, P, N, and S; R1, R2, R5, and R6are each independently selected from one or more of H, D, halogen, cyano, amino, nitro, C1-C20alkyl, C1-C20alkoxy, heteroaryl having 5 to 20 ring atoms, and C6-C20aryl. R1, R2, R5, and R6are each independently selected from one or more of H, D, halogen, cyano, amino, nitro, C1-C20alkyl, C1-C20alkoxy, heteroaryl having 5 to 20 ring atoms, and C6-C20aryl. R1, R2, R5, and R6are each independently selected from one or more of H, D

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