Carrier transport material, preparation method, light-emitting device and display panel

Abstract

This invention discloses a carrier transport material, its preparation method, a light-emitting device, and a display panel. The carrier transport material comprises composite particles, which include inorganic nanoparticles and organic structural units. The organic structural units are connected to the surface of the inorganic nanoparticles and include carbazole and / or fluorene structures. By connecting organic structural units containing carbazole and / or fluorene structures to the surface of inorganic nanoparticles, the inorganic nanoparticles and organic phases exhibit better compatibility. This significantly improves the problems of phase separation, rough film surface, and interfacial voids caused by inorganic nanoparticles. Simultaneously, it enhances carrier transport efficiency and energy level matching, making it suitable for large-area and low-temperature fabrication processes. Applying this carrier transport material to light-emitting devices can improve their performance.

Description

Technical Field

[0001] This invention belongs to the field of display technology, specifically relating to a carrier transport material, a preparation method, a light-emitting device, and a display panel. Background Technology

[0002] With the development of display technology, the application scenarios of displays are becoming increasingly widespread, and the performance requirements of displays vary in different application scenarios. Organic Light-Emitting Diodes (OLEDs) have received much attention and application due to their advantages such as low power consumption, excellent display effect, and low manufacturing cost. The principle of OLED display technology is to use electrons injected from the cathode and holes injected from the anode to recombine in the light-emitting layer to excite single-state excitons to emit light. Electrons need to be transported through the electron transport layer to reach the light-emitting layer, and holes need to be transported through the hole transport layer to reach the light-emitting layer. The performance of the transport layer has a significant impact on electrons or holes, thus affecting the light-emitting performance of the light-emitting device. Summary of the Invention

[0003] The purpose of this invention is to provide a carrier transport material, a preparation method, a light-emitting device, and a display panel to solve the problem that poor performance of the transport layer in a light-emitting device affects the device's light emission.

[0004] In a first aspect, embodiments of the present invention provide a carrier transport material, comprising: The composite particles comprise inorganic nanoparticles and organic structural units, wherein the organic structural units are connected to the surface of the inorganic nanoparticles and include carbazole and / or fluorene structures.

[0005] Further, the organic structural unit is formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a first group in the first compound, wherein the first compound includes a carbazole structure and / or a fluorene structure, and the first group includes at least one selected from carboxyl, phosphate, hydroxyl, and amino groups; and / or The inorganic nanoparticles have end-capping structural units attached to their surface. These end-capping structural units are formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a second group in a second compound. The second compound includes at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone. The second group includes at least one of carboxyl groups, phosphate groups, hydroxyl groups, and amino groups.

[0006] Furthermore, the carbazole structure and / or the fluorene structure are connected to an alkyl group; and / or The inorganic nanoparticles include metal oxide nanoparticles; and / or The inorganic nanoparticles include: NiO XWO3, MoO X At least one of V₂O₅, SnO₂, and ZnO, where x is greater than 0; and / or The inorganic nanoparticles have a particle size of 10-50 nm; and / or The particle size of the composite particles is 40-60 nm.

[0007] Furthermore, the material also includes: The polymer transport material includes at least one of poly(9-vinylcarbazole), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]. The structural formula of Poly-TPD is: ; The composite particles and the polymer transport material are dispersed in the dispersion solvent.

[0008] Furthermore, the total solid content of the composite particles and the polymer transport material is 5-15%; and / or The mass ratio of the composite particles to the polymer transport material is 1:9-3:7.

[0009] Secondly, embodiments of the present invention provide a method for preparing a carrier transport material, comprising: Inorganic nanoparticles are dispersed in the first solvent; An initial compound containing a carbazole structure and / or a fluorene structure is added to a first solvent to react with the initial compound and react with the groups on the surface of the inorganic nanoparticles to form composite particles; the composite particles include inorganic nanoparticles and organic structural units attached to the surface of the inorganic nanoparticles, wherein the organic structural units include carbazole structures and / or fluorene structures.

[0010] Furthermore, the inorganic nanoparticles have hydroxyl groups on their surface, the initial compound includes a first compound containing a first group, the hydroxyl groups on the surface of the inorganic nanoparticles react with the first group to form the organic structural unit, the first compound includes a carbazole structure and / or a fluorene structure, and the first group includes at least one selected from carboxyl, phosphate, hydroxyl, and amino groups; and / or Following the step of adding an initial compound containing a carbazole structure and / or a fluorene structure to a first solvent and reacting the initial compound with the groups on the surface of the inorganic nanoparticles to form composite particles, the preparation method further includes: The composite particles are mixed and reacted with a second compound containing a second group to attach end-capped structural units to the surface of the inorganic nanoparticles. The end-capping structural unit is formed by the reaction of the hydroxyl groups on the surface of the inorganic nanoparticles with the second group. The second compound includes at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone. The second group includes at least one of carboxyl groups, phosphate groups, hydroxyl groups, and amino groups.

[0011] Furthermore, the preparation method further includes: A carrier transport material is obtained by mixing composite particles with a polymer transport material and a dispersing solvent, such that the composite particles and the polymer transport material are dispersed in the dispersing solvent. The polymer transport material includes at least one of poly(9-vinylcarbazole), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]. The structural formula of Poly-TPD is as follows: .

[0012] Thirdly, embodiments of the present invention provide a light-emitting device, comprising: A first electrode, a carrier transport layer, a light-emitting layer, and a second electrode are stacked together. The carrier transport layer includes the carrier transport material described in the above embodiments, or the carrier transport material prepared by the preparation method described in the above embodiments.

[0013] Fourthly, embodiments of the present invention provide a display panel, comprising: The light-emitting device described in the above embodiments.

[0014] The charge carrier transport material of this invention comprises inorganic nanoparticles and organic structural units, wherein the organic structural units are connected to the surface of the inorganic nanoparticles, and the organic structural units include carbazole and / or fluorene structures. By connecting organic structural units containing carbazole and / or fluorene structures to the surface of inorganic nanoparticles, the inorganic nanoparticles and organic phases exhibit good compatibility. This significantly improves the problems of phase separation, rough film surface, and interfacial voids caused by inorganic nanoparticles, while also enhancing charge carrier transport efficiency and energy level matching. It is suitable for large-area and low-temperature fabrication processes. Applying this charge carrier transport material to light-emitting devices can improve the performance of these devices. Attached Figure Description

[0015] Figure 1 A schematic diagram illustrating the aggregation and phase separation states of existing transport materials; Figure 2 This is a schematic diagram showing the state in which the transport material of the present invention has not agglomerated or separated into phases; Figure 3A schematic diagram showing the surface of inorganic nanoparticles connected with organic structural units containing carbazole structures; Figure 4 This is a schematic diagram showing the surface of inorganic nanoparticles after modification with the first and second compounds. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The carrier transport material of this invention includes: The composite particles comprise inorganic nanoparticles and organic structural units, wherein the organic structural units are connected to the surface of the inorganic nanoparticles, and the organic structural units include carbazole and / or fluorene structures. The charge carrier transport material can be a hole transport material or an electron transport material. The inorganic nanoparticles can include metal oxide nanoparticles; for example, the inorganic nanoparticles can include at least one of WO3, MoOx, and V2O5, where x is greater than 0.

[0018] By attaching organic structural units containing carbazole and / or fluorene structures to the surface of inorganic nanoparticles, the inorganic nanoparticles and organic phases exhibit good compatibility. This significantly improves the problems of phase separation, rough film surface, and interfacial voids caused by inorganic nanoparticles. At the same time, it can improve the carrier transport efficiency and energy level matching, making it suitable for large-area and low-temperature fabrication processes. Applying this carrier transport material to light-emitting devices can improve the performance of the devices.

[0019] In some embodiments, the organic structural unit may be formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a first group in a first compound. The first compound may include a carbazole structure and / or a fluorene structure, and the first group may include at least one of a carboxyl group, a phosphate group, a hydroxyl group, and an amino group. For example, the first group may include a carboxyl group or a phosphate group, such that the organic structural unit can be firmly attached to the surface of the inorganic nanoparticles. The first compound may include: a fluorene compound containing a carboxylic acid group or a phosphate group, or a derivative of a triarylamine containing a carboxylic acid group or a phosphate group.

[0020] In other embodiments, the surface of the inorganic nanoparticles may be connected with end-capping structural units. These end-capping structural units can be formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a second group in a second compound. The second compound may include at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone (PVP). The second group may include at least one of carboxyl, phosphate, hydroxyl, and amino groups; for example, the second group may include a carboxyl or phosphate group. After the hydroxyl groups on the surface of the inorganic nanoparticles react with the first group in the first compound, organic structural units containing carbazole and / or fluorene structures are formed. Hydroxyl groups remain on the surface of the inorganic nanoparticles that have not participated in the reaction, and these hydroxyl groups can react with the second group in the second compound.

[0021] In some embodiments, an alkyl group is attached to the carbazole structure and / or the fluorene structure. The alkyl group may include methyl, ethyl, etc. Attaching an alkyl group to the carbazole structure and / or the fluorene structure can improve the compatibility of inorganic nanoparticles with the organic phase. The carboxyl group can react with the hydroxyl groups on the surface of the metal oxide, the alkyl chain can increase the compatibility with the organic phase, and the carbazole / fluorene structure can provide a hole transport channel.

[0022] The inorganic nanoparticles include metal oxide nanoparticles. Inorganic nanoparticles may include: NiO X WO3, MoO X At least one of V₂O₅, SnO₂, and ZnO, where x is greater than 0. For example, when the charge carrier transport material is a hole transport material, inorganic nanoparticles may include: NiO X WO3, MoO X At least one of V2O5; when the charge carrier transport material is an electron transport material, the inorganic nanoparticles may include at least one of SnO2 and ZnO.

[0023] The particle size of the inorganic nanoparticles can be 10-50 nm. For example, the particle size of the inorganic nanoparticles can be 10-25 nm, 20-30 nm, or 30-50 nm. The particle size of the inorganic nanoparticles can be reasonably selected according to specific circumstances.

[0024] The particle size of the composite particles can be 40-60 nm, 40-50 nm, or 45-60 nm. The particle size of the composite particles can be reasonably selected according to specific circumstances.

[0025] Optionally, the charge carrier transport material may also include: The polymer transport material and dispersing solvent, wherein the polymer transport material may include at least one of: poly(9-vinylcarbazole) (PVK), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), wherein the structural formula of Poly-TPD is: ; The composite particles and polymer transport materials can be dispersed in a dispersion solvent. The dispersion solvent can be an organic solvent, and may include at least one of chlorobenzene, toluene, and dichlorobenzene.

[0026] Optionally, the total solid content of the composite particles and the polymer transport material can be 5-15%, for example, the total solid content of the composite particles and the polymer transport material can be 5%, 8%, 12% or 15%, and the specific solid content can be adjusted according to actual needs.

[0027] Optionally, the mass ratio of the composite particles to the polymer transport material can be 1:9 to 3:7. For example, the mass ratio of the composite particles to the polymer transport material can be 1:9, 2:9, 1:3 or 3:7. The specific mass ratio can be selected according to actual needs.

[0028] The method for preparing the carrier transport material according to an embodiment of the present invention includes: Inorganic nanoparticles are dispersed in the first solvent; An initial compound containing a carbazole structure and / or a fluorene structure is added to a first solvent to react with the initial compound and react with the groups on the surface of the inorganic nanoparticles to form composite particles; the composite particles include inorganic nanoparticles and organic structural units attached to the surface of the inorganic nanoparticles, wherein the organic structural units include carbazole structures and / or fluorene structures. This method allows for the attachment of organic structural units containing carbazole and / or fluorene structures to the surface of inorganic nanoparticles, resulting in better compatibility between the inorganic nanoparticles and the organic phase. It significantly improves the problems of phase separation, rough film surface, and interfacial voids caused by inorganic nanoparticles. Simultaneously, it enhances carrier transport efficiency and energy level matching, making it suitable for large-area and low-temperature fabrication processes. This method overcomes the problems of easy aggregation and phase separation of inorganic particles in polymer matrices leading to high film roughness. Without sacrificing hole migration performance, it achieves long-term storage and good dispersion stability, taking into account the polarity differences between polymers and inorganic phases. It optimizes solvents and film-forming processes, improving coating consistency and industrial feasibility. Applying this carrier transport material to light-emitting devices can improve their performance.

[0029] During the preparation process, the first solvent may include alcohol solvents, such as ethanol and isopropanol, to promote surface reactions. The surface groups of the inorganic nanoparticles may be hydroxyl groups. The inorganic nanoparticles may include metal oxide nanoparticles, and may include NiO. X WO3, MoO X Inorganic nanoparticles may include at least one of V₂O₅, SnO₂, and ZnO. For example, when the charge carrier transport material is a hole transport material, the inorganic nanoparticles may include: NiO. X WO3, MoO X The inorganic nanoparticles may include at least one of the following: SnO2 and V2O5; when the carrier transport material is an electron transport material, the inorganic nanoparticles may include at least one of SnO2 and ZnO. The particle size of the inorganic nanoparticles may be 10-50 nm, for example, the particle size of the inorganic nanoparticles may be 10-25 nm, 20-30 nm, or 30-50 nm, and the particle size of the inorganic nanoparticles may be reasonably selected according to specific circumstances.

[0030] The particle size of the composite particles can be 40-60 nm, 40-50 nm, or 45-60 nm, and the particle size can be reasonably selected according to specific circumstances. Different particle sizes can be selected as needed; for example, the particle size can also be selected as 40-200 nm, and the specific particle size is not limited.

[0031] In some embodiments, the inorganic nanoparticles have hydroxyl groups on their surface, and the initial compound includes a first compound containing a first group. The hydroxyl groups on the surface of the inorganic nanoparticles react with the first group to form the organic structural unit. The first compound includes a carbazole structure and / or a fluorene structure, and the first group includes at least one of a carboxyl group, a phosphate group, a hydroxyl group, and an amino group. The first compound can be a compound including a long alkyl chain, a carboxyl group, and a hole transport unit (carbazole or fluorene), for example, C 12 -Carbazole-carboxylic acid / phosphate, C8-fluorene-carboxylic acid / phosphate or a compound having the structural formula (1).

[0032] The first compound can be a compound having structural formula (1), which is: ; Following the step of adding an initial compound containing a carbazole structure and / or a fluorene structure to a first solvent and reacting the initial compound with groups on the surface of the inorganic nanoparticles to form composite particles, the preparation method may further include: The composite particles are mixed and reacted with a second compound containing a second group to attach end-capped structural units to the surface of the inorganic nanoparticles. The end-capping structural unit is formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with the second group. The second compound includes at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone. The second group includes at least one of carboxyl, phosphate, hydroxyl, and amino groups. The second compound may include: polyethylene glycol (PEG) or block copolymers with phosphate groups, modified polyvinylpyrrolidone (PVP), etc. For example, the second compound may include at least one of polyethylene glycol phosphate, carboxyl-polyethylene glycol-carboxyl, and methoxy polyethylene glycol phosphate.

[0033] After the hydroxyl groups on the surface of inorganic nanoparticles react with the first group in the first compound, organic structural units containing carbazole and / or fluorene structures are formed. Residual hydroxyl groups remain on the surface of the inorganic nanoparticles and do not participate in the reaction. These residual hydroxyl groups can react with the second group in the second compound to form end-capped structural units. These end-capped structural units can improve the surface defects of the inorganic nanoparticles. The second compound can be a polyether containing phosphate or carboxylic acid groups, a fluorinated block copolymer, or a modified polyvinylpyrrolidone (PVP), etc. The phosphate or carboxylic acid groups can react and bind with the residual hydroxyl groups on the surface of the inorganic nanoparticles, providing steric hindrance.

[0034] By modifying the surface of inorganic nanoparticles with a bilayer of compounds, long-term dispersion and structural stability of inorganic particles can be achieved. The first compound, through reaction, is attached to the surface of inorganic nanoparticles to provide hole transport function and regulate surface energy, thereby enhancing compatibility with polymer matrices. The second compound, through reaction, is attached to the surface of inorganic nanoparticles to cap unreacted hydroxyl groups and inhibit secondary aggregation. This improves the flatness of the film during the preparation of the film, enhances the work function matching, increases carrier mobility, and provides strong process compatibility, making it suitable for printable processes such as spin coating, slot coating, and inkjet printing.

[0035] In some embodiments, the preparation method may further include: A carrier transport material is obtained by mixing composite particles with a polymer transport material and a dispersing solvent, such that the composite particles and the polymer transport material are dispersed in the dispersing solvent. The polymer transport material includes at least one of poly(9-vinylcarbazole) (PVK), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), wherein the structural formula of Poly-TPD is: ; The dispersing solvent may include at least one of chlorobenzene, toluene, or dichlorobenzene. The total solid content of the composite particles and the polymer transport material may be 5-15%, for example, 5%, 8%, 12%, or 15%, and the specific solid content can be adjusted according to actual needs. The mass ratio of the composite particles to the polymer transport material may be 1:9-3:7, for example, 1:9, 2:9, 1:3, or 3:7, and the specific mass ratio can be selected according to actual needs.

[0036] like Figure 1 As shown, existing hole transport materials, when mixed with unmodified inorganic nanoparticles and polymer transport materials, exhibit problems of aggregation and phase separation. For example... Figure 2 As shown, the composite particles in this invention do not exhibit agglomeration or phase separation issues after being mixed with the polymer transport material, and the organic polymer transport material has good compatibility with the inorganic particles.

[0037] The preparation process may include the following steps: (1) Inorganic nanoparticles can be metal oxide particles, and the surface of inorganic nanoparticles has hydroxyl groups; Metal oxide particles are dispersed in isopropanol, and the solid content of the metal oxide particles can be 1-5 wt%. Then, a first compound containing carbazole-carboxylic acid / phosphate groups is added. The mass ratio of the first compound can be 2-8 wt% of the inorganic nanoparticles to provide a sufficient organic coating layer on the surface of the inorganic nanoparticles. The mixture is stirred or sonicated at 20-60°C for 2-3 hours to allow the carboxylic acid / phosphate groups to react with the hydroxyl groups on the surface of the inorganic nanoparticles to form a stable organic structural unit. Then, centrifugation and washing are performed to remove unbound first compound, yielding inorganic nanoparticles modified with the first compound, which can be used as follows: Figure 3 As shown, organic structural units containing carbazole (Cz) are attached to the surface of inorganic nanoparticles; (2) The modified inorganic nanoparticles are redispersed in isopropanol, and a second compound is added. The mass of the second compound can be 0.5-3 wt% of the mass of the inorganic nanoparticles. The mixture is stirred at 20-60℃ for 1-2 h. The second group in the second compound combines with the unreacted hydroxyl groups on the surface of the inorganic nanoparticles to form a protective layer. The second compound can prevent particle aggregation and regulate the surface energy of the particles. Figure 4As shown, organic structural units containing carbazole and end-capped structural units are connected to the surface of inorganic nanoparticles; particle size analysis confirms that the average particle size is between 40-60 nm. The mass ratio of the first compound to the second compound can be 2:1-4:1, which can balance surface functionality and stability. (3) A stepwise solvent exchange can be used, with chlorobenzene or dichlorobenzene solvent added slowly while isopropanol is evaporated to ensure that the particles do not aggregate during the transfer process; Add a polymer transport material (e.g., PVK, 10 mg / mL), mix and stir or sonicate for 20-60 min to prepare a carrier transport material, which can have good mobility and film density.

[0038] If the prepared carrier transport material system is biased towards polarity, 2-5% isopropanol (IPA) can be added as a co-solvent to improve short-term stability.

[0039] In the process of preparing a charge carrier transport layer using a charge carrier transport material, the material can be coated by spin coating or slot coating (2000 rpm, 30 s). The drying temperature can be 100-120℃, and the drying time can be 5-30 min. After drying, a smooth film layer is formed, and the surface roughness of the film layer can be Ra2-10 nm. In the process of preparing the charge carrier transport layer using the material, ultraviolet (UV) crosslinking can also be selected to enhance solvent resistance.

[0040] The light-emitting device of this invention includes: A first electrode, a carrier transport layer, a light-emitting layer, and a second electrode are stacked together. The carrier transport layer includes the carrier transport material described in the above embodiments, or the carrier transport material prepared by the preparation method described in the above embodiments. When the carrier transport layer is a hole transport layer, the first electrode is the anode and the second electrode is the cathode; when the carrier transport layer is an electron transport layer, the second electrode is the anode and the first electrode is the cathode. The light-emitting device may include a cathode (thickness 5-15nm), an electron injection layer (3-10nm), an electron transport layer (5-15nm), a light-emitting layer (15-50nm), a hole transport layer (10-40nm), a hole injection layer (8-20nm), and an anode (15-50nm) stacked together. The hole transport layer or the electron transport layer may use the carrier transport material of the present invention.

[0041] The display panel of this invention includes: The light-emitting device described in the above embodiments.

[0042] The present invention will be further illustrated below through some specific embodiments.

[0043] Example 1: The first compound is: ; The preparation process may include the following steps: (1) Disperse nickel oxide particles in isopropanol. The solid content of the nickel oxide particles is 1 wt%, and the particle size is 20-50 nm. Then the first compound was added, with a mass of 2 wt% of the nickel oxide particles. The mixture was stirred at 20°C for 2 h to allow the phosphate groups to react with the hydroxyl groups on the surface of the nickel oxide particles. Then, centrifugation and washing were performed to remove unbound first compound, yielding nickel oxide particles modified with the first compound. (2) The modified nickel oxide particles were redispersed in isopropanol, and the second compound was added and stirred at 20°C for 2 hours to obtain composite particles. The mass of the second compound was 0.5 wt% of the mass of the nickel oxide particles, and the second compound was polyethylene glycol phosphate. (3) A gradual solvent exchange was adopted, chlorobenzene solvent was slowly added, isopropanol was evaporated at the same time, and polymer transport material was added and mixed and stirred for 20 min. The polymer transport material was poly(9-vinylcarbazole) (PVK), and the mass ratio of composite particles to polymer transport material was 1:9. Hole transport material was prepared.

[0044] Example 2: The first compound is: ; The preparation process may include the following steps: (1) Disperse nickel oxide particles in isopropanol. The solid content of the nickel oxide particles is 5wt% and the particle size is 20-50nm. Then, the first compound is added, the mass of which can be 8 wt% of the mass of the nickel oxide particles; the mixture is stirred at 60 °C for 3 h to allow the phosphate groups to react with the hydroxyl groups on the surface of the nickel oxide particles; Then, centrifugation and washing were performed to remove unbound first compound, yielding nickel oxide particles modified with the first compound. (2) The modified nickel oxide particles were redispersed in isopropanol, and the second compound was added and stirred at 60°C for 1 h. The mass of the second compound was 3 wt% of the mass of the nickel oxide particles. The second compound was carboxyl-polyethylene glycol-carboxyl. (3) A gradual solvent exchange was adopted, chlorobenzene solvent was slowly added, isopropanol was evaporated at the same time, and polymer transport material was added and mixed and stirred for 20 min. The polymer transport material was poly(9-vinylcarbazole) (PVK), and the mass ratio of composite particles to polymer transport material was 3:7. Hole transport material was prepared.

[0045] Example 3: The first compound is: ; The preparation process may include the following steps: (1) Disperse nickel oxide particles in isopropanol. The solid content of the nickel oxide particles can be 3wt% and the particle size can be 20-50nm. Then the first compound is added, the mass of which can be 5 wt% of the mass of the nickel oxide particles; the mixture is stirred at 40 °C for 2.5 h to allow the phosphate groups to react with the hydroxyl groups on the surface of the nickel oxide particles; Then, centrifugation and washing were performed to remove unbound first compound, yielding nickel oxide particles modified with the first compound. (2) The modified nickel oxide particles were redispersed in isopropanol, and the second compound was added and stirred at 45°C for 1.5 h. The mass of the second compound was 2 wt% of the mass of the nickel oxide particles, and the second compound was polyethylene glycol phosphate. (3) A gradual solvent exchange was adopted, chlorobenzene solvent was slowly added, isopropanol was evaporated at the same time, and polymer transport material was added and mixed and stirred for 20 min. The polymer transport material was poly(9-vinylcarbazole) (PVK), and the mass ratio of composite particles to polymer transport material was 1:3. Hole transport material was prepared.

[0046] Example 4: The difference between Example 4 and Example 3 is as follows: Nickel oxide particles were replaced with WO3 particles.

[0047] Example 5: The difference between Example 5 and Example 3 is as follows: The polymer transport material was replaced with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0048] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is as follows: The hole transport material is unmodified nickel oxide particles.

[0049] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is as follows: The hole transport material is PVK.

[0050] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is as follows: Hole transport material is prepared by mixing untreated nickel oxide particles with polymer transport material.

[0051] Comparative Example 4: The difference between Comparative Example 4 and Example 4 is as follows: The hole transport material is unmodified WO3 particles.

[0052] Comparative Example 5: The difference between Comparative Example 5 and Example 4 is as follows: Hole transport material is a hole transport material prepared by mixing untreated WO3 particles with a polymer transport material.

[0053] Comparative Example 6: The difference between Comparative Example 6 and Example 5 is as follows: The hole transport material is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0054] Comparative Example 7: The difference between Comparative Example 7 and Example 5 is as follows: The hole transport material is a hole transport material prepared by mixing untreated nickel oxide particles with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0055] Light-emitting devices were fabricated using the hole transport materials prepared in the above embodiments and comparative examples. The light-emitting devices included a cathode (thickness of 5-15 nm), an electron injection layer (3-10 nm), an electron transport layer (5-15 nm), a light-emitting layer (15-50 nm), a hole transport layer (10-40 nm), a hole injection layer (8-20 nm), and an anode (15-50 nm) stacked together. The hole transport layer was the hole transport material prepared in the above embodiments and comparative examples. The performance of the light-emitting devices in the above embodiments and comparative examples was tested, and the specific test results are shown in Table 1.

[0056] Table 1 Performance test results of the light-emitting devices in the above embodiments and comparative examples ; As shown in Table 1, the light-emitting devices prepared from the hole transport materials in the above embodiments of the present invention have high external quantum efficiency and good lifespan, which can improve the performance of the devices.

[0057] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A carrier transport material, characterized in that, include: The composite particles comprise inorganic nanoparticles and organic structural units, wherein the organic structural units are connected to the surface of the inorganic nanoparticles and include carbazole and / or fluorene structures.

2. The material according to claim 1, characterized in that, The organic structural unit is formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a first group in a first compound, wherein the first compound includes a carbazole structure and / or a fluorene structure, and the first group includes at least one selected from carboxyl, phosphate, hydroxyl, and amino groups; and / or The inorganic nanoparticles have end-capping structural units attached to their surface. These end-capping structural units are formed by the reaction of hydroxyl groups on the surface of the inorganic nanoparticles with a second group in a second compound. The second compound includes at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone. The second group includes at least one of carboxyl groups, phosphate groups, hydroxyl groups, and amino groups.

3. The material according to claim 1, characterized in that, The carbazole structure and / or the fluorene structure are connected to an alkyl group; and / or The inorganic nanoparticles include metal oxide nanoparticles; and / or The inorganic nanoparticles include: NiO X WO3, MoO X At least one of V₂O₅, SnO₂, and ZnO, where x is greater than 0; and / or The inorganic nanoparticles have a particle size of 10-50 nm; and / or The particle size of the composite particles is 40-60 nm.

4. The material according to claim 1, characterized in that, Also includes: The polymer transport material includes at least one of poly(9-vinylcarbazole), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]. The structural formula of Poly-TPD is: ； The composite particles and the polymer transport material are dispersed in the dispersion solvent.

5. The material according to claim 4, characterized in that, The total solids content of the composite particles and the polymer transport material is 5-15%; and / or The mass ratio of the composite particles to the polymer transport material is 1:9-3:

7.

6. A method for preparing a charge carrier transport material, characterized in that, include: Inorganic nanoparticles are dispersed in the first solvent; An initial compound containing a carbazole structure and / or a fluorene structure is added to a first solvent to react with the initial compound and react with the groups on the surface of the inorganic nanoparticles to form composite particles; the composite particles include inorganic nanoparticles and organic structural units attached to the surface of the inorganic nanoparticles, wherein the organic structural units include carbazole structures and / or fluorene structures.

7. The preparation method according to claim 6, characterized in that, The inorganic nanoparticles have hydroxyl groups on their surface. The initial compound includes a first compound containing a first group. The hydroxyl groups on the surface of the inorganic nanoparticles react with the first group to form the organic structural unit. The first compound includes a carbazole structure and / or a fluorene structure. The first group includes at least one of a carboxyl group, a phosphate group, a hydroxyl group, and an amino group; and / or Following the step of adding an initial compound containing a carbazole structure and / or a fluorene structure to a first solvent and reacting the initial compound with the groups on the surface of the inorganic nanoparticles to form composite particles, the preparation method further includes: The composite particles are mixed and reacted with a second compound containing a second group to attach end-capped structural units to the surface of the inorganic nanoparticles. The end-capping structural unit is formed by the reaction of the hydroxyl groups on the surface of the inorganic nanoparticles with the second group. The second compound includes at least one of polyethers containing the second group, fluorinated block copolymers, and modified polyvinylpyrrolidone. The second group includes at least one of carboxyl groups, phosphate groups, hydroxyl groups, and amino groups.

8. The preparation method according to claim 6 or 7, characterized in that, Also includes: A carrier transport material is obtained by mixing composite particles with a polymer transport material and a dispersion solvent, such that the composite particles and the polymer transport material are dispersed in the dispersion solvent. The polymer transport material includes at least one of poly(9-vinylcarbazole), Poly-TPD, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]. The structural formula of Poly-TPD is: 。 9. A light-emitting device, characterized in that, include: A first electrode, a carrier transport layer, a light-emitting layer, and a second electrode are stacked together. The carrier transport layer comprises the carrier transport material according to any one of claims 1-5, or the carrier transport material prepared by the preparation method according to any one of claims 6-8.

10. A display panel, characterized in that, include: The light-emitting device according to claim 9.

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