Quantum dot film, preparation method thereof and light-emitting device

Abstract

The invention belongs to the technical field of display, and relates to a quantum dot film, a preparation method and a light-emitting device. The preparation method of the quantum dot film comprises the following steps: providing a quantum dot solution comprising a quantum dot material and a second solvent, and volatilizing the second solvent in the quantum dot solution to form the quantum dot film; wherein the quantum dot film comprises a quantum dot material and a fluorine element. The quantum dot film prepared by the invention contains fluorine-containing elements, and fluorine has very large electronegativity and is hardly excited, so that the surface energy of the quantum dot film can be reduced, and the quantum dot film has a lyophobic characteristic and can isolate water and oxygen.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and in particular, to a quantum dot film, a preparation method thereof, and a light-emitting device. Background Art

[0002] In the prior art, when preparing an electron transport layer, the phenomenon that water and oxygen penetrate through the light-emitting layer and permeate into the hole functional layer may occur, resulting in the destruction of the hole functional layer material, and further reducing the service life of the light-emitting device. Summary of the Invention

[0003] Based on this, embodiments of the present application provide a quantum dot film, a preparation method thereof, and a light-emitting device.

[0004] In order to solve the above technical problems, an embodiment of the present application provides a method for preparing a quantum dot film. The method for preparing the quantum dot film adopts the following technical solutions:

[0005] Provide a quantum dot solution including a quantum dot material and a second solvent, and volatilize the second solvent in the quantum dot solution to form a quantum dot film; wherein, the material of the quantum dot film includes a quantum dot material and fluorine element.

[0006] Further, the step of forming the quantum dot film includes:

[0007] Perform a drying treatment on the quantum dot solution to form a prefabricated film;

[0008] Perform a ligand exchange treatment on the prefabricated film with a fluorine-containing organic ligand to form a quantum dot film containing fluorine element;

[0009] Optionally, the fluorine-containing organic ligand includes at least one of fluorinated aliphatic thiol, fluorinated fatty acid, fluorinated aliphatic amine, fluorinated aliphatic alcohol, and fluorinated aromatic hydrocarbon.

[0010] Further, the step of performing a ligand exchange treatment on the prefabricated film with a fluorine-containing organic ligand includes:

[0011] Provide a fluorine-containing treatment liquid, and the fluorine-containing treatment liquid includes a fluorine-containing organic ligand and a first solvent;

[0012] Immerse the prefabricated film in the fluorine-containing treatment liquid for 10 min to 30 min, and the immersion temperature is 10°C to 25°C;

[0013] One of the first solvent and the second solvent is a polar solvent, and the other is a non-polar solvent;

[0014] Optionally, the fluorinated organic ligand is selected from at least one of trifluoromethyl mercaptan, trifluoroethyl mercaptan, trifluoroacetic acid, perfluorooctylamine, trifluoromethylamine, trifluoromethanol, perfluorodimercaptopropanol, hexafluorobenzene, and fluorinated catechol; and / or,

[0015] The first solvent includes at least one of alkanes with 5 to 12 carbon atoms, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO, and ether, and the second solvent includes at least one of alkanes with 5 to 12 carbon atoms, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO, and ether; and / or,

[0016] The mass ratio of the fluorinated organic ligand to the first solvent is 1:5 to 1:20;

[0017] and / or, the concentration of the quantum dot material in the quantum dot solution is 5 mg / ml to 50 mg / ml.

[0018] Further, before the step of providing the quantum dot solution including the quantum dot material and the second solvent, there is also a step:

[0019] Provide a quantum dot material, a second solvent, and a fluorinated material; wherein, the fluorinated material includes a fluorinated organic ligand and / or a fluorinated polymer;

[0020] Mix the quantum dot material, the second solvent, and the fluorinated material to form the quantum dot solution.

[0021] Further, when the fluorinated material only includes a fluorinated organic ligand, the mass ratio of the fluorinated organic ligand to the quantum dot material in the quantum dot solution is 5% to 15%; or,

[0022] when the fluorinated material only includes a fluorinated polymer, the mass ratio of the fluorinated polymer to the quantum dot material in the quantum dot solution is 2% to 15%; and / or,

[0023] The step of volatilizing the second solvent in the quantum dot solution to form a quantum dot film includes: drying the quantum dot solution to form a quantum dot film.

[0024] Further, the fluorinated organic ligand is selected from at least one of trifluoromethyl mercaptan, trifluoroethyl mercaptan, trifluoroacetic acid, perfluorooctylamine, trifluoromethylamine, trifluoromethanol, perfluorodimercaptopropanol, hexafluorobenzene, and fluorinated catechol; and / or,

[0025] The second solvent includes at least one of alkanes with 5 to 12 carbon atoms, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO, and ethyl; and / or,

[0026] The fluorine-containing polymer includes one or a combination of polytetrafluoroethylene, polytrifluorochloroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, ethylene-trifluorochloroethylene copolymer, polyvinyl fluoride, tetrafluoroethylene / perfluoroalkyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, fluorinated polyimide, and perfluoropolyether.

[0027] Further, the preparation method further includes the following step: performing CF4 plasma treatment on the quantum dot thin film.

[0028] Further, the quantum dot material includes group II-VI compound semiconductors and their core-shell structures, group III-V or group IV-VI compound semiconductors and their core-shell structures;

[0029] The group II-VI semiconductor compounds include at least one of CdSe, CdTe, CdO, CdS, ZnSe, HgO, HgS, HgSe, CdSeS, CdSeTe, CdSTe, CdZnS, CdZnSe, SiSeTe, HgSeS, HgSTe, HgSiS, HgSeSe, CdZnSeTe, HgSiSTe, HgSiSeS; and / or,

[0030] The group III-V semiconductor compounds include at least one of A1N, AlP, AlAs, AlSb, GaN, GaP, A1NP, AlNAs, AlNSb, AlPAs, AlPSb, GaNP, GaNAs, GaPAs, GaPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNAs, GaAlN, GaAlPAs, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP; and / or,

[0031] The group IV-VI semiconductor compounds include at least one of SnSe, SnTe, PbSe, PbS, PbTe, SnSeS, SnSeTe, SnSTe, SnPbS, SnPbSe, SnPbTe, PbSTe, PbSeS, PbSeTe, SnPbSSe, SnPbSeTe, SnPbSTe; and / or,

[0032] The average particle size of the quantum dot material is 5 nm to 20 nm.

[0033] Correspondingly, the present application also provides a quantum dot thin film, and the thin film is prepared by using the preparation method of the quantum dot thin film as described above.

[0034] Correspondingly, the present application also provides a light-emitting device, which includes a light-emitting layer. It is characterized in that the light-emitting layer is prepared by the method for preparing a quantum dot thin film as described above, or uses the quantum dot thin film as described above.

[0035] Compared with the prior art, the embodiments of the present application can reduce the surface energy of the quantum dot thin film and improve the service life of the light-emitting device. Description of the Drawings

[0036] In order to more clearly illustrate the solutions in the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 is a flowchart of the method for preparing a quantum dot thin film according to an embodiment of the present application;

[0038] Figure 2 is a flowchart of the method for preparing a quantum dot thin film according to another embodiment of the present application;

[0039] Figure 3 is a flowchart of the method for preparing a quantum dot thin film according to another embodiment of the present application;

[0040] Figure 4 is a schematic structural diagram of a light-emitting device according to an embodiment of the present application.

[0041] Reference Signs:

[0042] First electrode 100, hole functional layer 200, light-emitting layer 300, electron functional layer 400, second electrode 500. Detailed Embodiments

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0044] In this application, unless otherwise specified, the orientation terms such as "upper" and "lower" generally refer to the upper and lower directions in the actual use or working state of the device, specifically the drawing directions in the attached drawings; while "inner" and "outer" refer to the outline of the device. Additionally, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0045] In this application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural.

[0046] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0047] The various embodiments of this application can exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub - ranges and the single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0048] Please refer to Figure 1 , this application provides a method for preparing a quantum dot thin film, and the method includes

[0049] providing a quantum dot solution including a quantum dot material and a second solvent, and volatilizing the second solvent in the quantum dot solution to form a quantum dot thin film;

[0050] wherein, the material of the quantum dot thin film includes a quantum dot material and fluorine element.

[0051] The quantum dot thin film prepared in the embodiment of the present application includes fluorine element. Fluorine has a very high electronegativity and can hardly be polarized. Therefore, the fluorine element can reduce the surface energy of the quantum dot thin film, and further endow the quantum dot thin film with liquid repellent properties. In summary, when the quantum dot thin film of the present application is used as the light-emitting layer, it can prevent the solution of the electron transport layer from penetrating into the hole functional layer during the preparation of the electron transport layer, thereby avoiding damage to the hole functional layer. It can be understood that the surface energy of the quantum dot thin film can be less than 72.8 mN / m, thus preventing water from penetrating through the quantum dot thin film.

[0052] Further, the steps of forming the quantum dot thin film include: drying the quantum dot solution to form a prefabricated thin film; performing ligand exchange treatment on the prefabricated thin film with a fluorine-containing organic ligand to form a quantum dot thin film containing fluorine element.

[0053] At this time, the steps of the preparation method of the quantum dot thin film are as follows:

[0054] S10, providing a quantum dot solution including a quantum dot material and a second solvent;

[0055] S20, drying the quantum dot solution to form a prefabricated thin film;

[0056] S30, performing ligand exchange treatment on the prefabricated thin film with a fluorine-containing organic ligand to form a quantum dot thin film containing fluorine element.

[0057] To make the quantum dot thin film contain fluorine element, the quantum dot solution can be dried to first form a prefabricated thin film, and then a fluorine-containing ligand exchange treatment is performed on the prefabricated thin film, so that the quantum dot material in the prefabricated thin film undergoes ligand exchange with the fluorine-containing ligand to form a fluorine-containing material. At this time, because the quantum dot thin film contains fluorine element, the quantum dot thin film has liquid repellency.

[0058] It can be understood that the fluorine-containing organic ligand contains a fluorocarbon bond. Therefore, the solution including the fluorine-containing organic ligand is more stable than the solution including the fluorine-containing inorganic ligand. Thus, it can improve the control accuracy of the fluorine content of the quantum dot thin film, and can also prevent the fluorine-containing ligand solution from decomposing or undergoing other chemical reactions before ligand exchange with the prefabricated thin film, resulting in a reduction in the ligand exchange rate between the prefabricated thin film and the fluorine-containing ligand. It can be understood that the fluorine-containing organic ligand includes at least one of fluorinated aliphatic thiol, fluorinated fatty acid, fluorinated aliphatic amine, fluorinated aliphatic alcohol, and fluorinated aromatic hydrocarbon.

[0059] When the fluorinated organic ligand is a fluorinated aliphatic thiol, the fluorinated organic ligand includes at least one of materials such as trifluoromethylthiol and trifluoroethylthiol; when the fluorinated organic ligand is a fluorinated fatty acid, the fluorinated organic ligand includes at least one of materials such as trifluoroacetic acid and trifluoropropionic acid; when the fluorinated organic ligand is a fluorinated aliphatic amine, the fluorinated organic ligand includes trifluoromethylamine and perfluorooctylamine; when the fluorinated organic ligand is a fluorinated aliphatic alcohol, the fluorinated organic ligand includes trifluoromethanol and perfluorodimercaptopropanol; when the fluorinated organic ligand is a fluorinated aromatic hydrocarbon, the fluorinated organic ligand includes hexafluorobenzene and fluorinated catechol.

[0060] Further, the steps of performing fluorinated organic ligand exchange treatment on the prefabricated film with the fluorinated organic ligand include:

[0061] Providing a fluorinated treatment solution, the fluorinated treatment solution includes a fluorinated organic ligand and a first solvent;

[0062] Immersing the prefabricated film in the fluorinated treatment solution for 10 min to 30 min, and the immersion temperature is 10°C to 25°C;

[0063] The quantum dot solution includes a quantum dot material and a second solvent;

[0064] One of the first solvent and the second solvent is a polar solvent, and the other is a non-polar solvent;

[0065] The first solvent includes at least one of alkanes with C5 - C12, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO, and ether, and the second solvent includes at least one of alkanes with C5 - C12, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO, and ether; and / or,

[0066] The mass ratio of the fluorinated organic ligand to the first solvent is 1:5 to 1:20;

[0067] And / or, the concentration of the quantum dot material in the quantum dot solution is 5 mg / ml to 50 mg / ml.

[0068] At this temperature, adverse reactions between the fluorine-containing treatment liquid and the prefabricated film can be avoided, which affects the exchange rate of the fluorine-containing organic ligand. Within this time range, sufficient exchange between the prefabricated film and the fluorine-containing organic ligand can be ensured. It can be understood that the soaking time can be any value among 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min or the range formed by any two of these values. The soaking temperature can be any value among 10 °C, 11 °C, 12 °C, 13 °C, 14 °C, 15 °C, 16 °C, 17 °C, 18 °C, 19 °C, 20 °C, 21 °C, 22 °C, 23 °C, 24 °C, 25 °C or the range formed by any two of these values.

[0069] Furthermore, when the mass ratio of the fluorine-containing organic ligand to the first solvent is 1:5 to 1:20, the fluorine-containing treatment liquid can have good fluidity, thereby improving the morphological uniformity of the quantum dot film. It can be understood that when a polar solution is used as the second solvent when preparing the quantum dot film, since the first solvent of the fluorine-containing treatment liquid in the embodiments of the present application uses a non-polar solvent, the non-polar solvent can form an orthogonality with the polar solvent, so that the reaction between the fluorine-containing treatment liquid and the quantum dot film can be avoided, thereby avoiding damage to the quantum dot film. It can be understood that the mass ratio of the fluorine-containing organic ligand to the non-polar solvent includes any value among 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20 or the range formed by any two of these values. The concentration of the quantum dot material in the quantum dot solution can ensure the luminescence performance of the quantum film, and its concentration can be any value among 5 mg / ml, 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, 30 mg / ml, 35 mg / ml, 40 mg / ml, 45 mg / ml, 50 mg / ml or the range formed by any two of these values.

[0070] Furthermore, before the step of providing the quantum dot solution including the quantum dot material and the second solvent, the steps further include: providing the quantum dot material, the second solvent, and the fluorine-containing material; mixing the quantum dot material, the second solvent, and the fluorine-containing material to form a quantum dot solution; wherein, the fluorine-containing material includes a fluorine-containing organic ligand and / or a fluorine-containing polymer.

[0071] At this time, please refer to Figure 2 , the steps of the preparation method of the quantum dot film are as follows:

[0072] S1, providing the quantum dot material, the second solvent, and the fluorine-containing material;

[0073] S2, mixing the quantum dot material, the second solvent, and the fluorine-containing material to form a quantum dot solution, wherein the fluorine-containing material includes a fluorine-containing organic ligand and / or a fluorine-containing polymer;

[0074] S3, volatilize the second solvent in the quantum dot solution to form a quantum dot film; wherein the quantum dot film includes quantum dot material and fluorine element.

[0075] In this embodiment, before the quantum dot solution is made into a quantum dot film, a fluorine-containing organic ligand and / or a fluorine-containing polymer is added to the quantum dot solution, so that after the quantum dot solution is placed on the substrate to form a quantum dot film, the quantum dot film contains fluorine elements uniformly, thereby making the liquid repellency of the quantum dot film uniform everywhere, which can further improve the service life of the quantum dot film.

[0076] Furthermore, when the fluorine-containing material only includes fluorine-containing organic ligands, the mass ratio of fluorine-containing organic ligands to quantum dot materials in the quantum dot solution is 5% to 15%; or, when the fluorine-containing material only includes fluorine-containing polymers, the mass ratio of fluorine-containing polymers to quantum dot materials in the quantum dot solution is 2% to 15%; or, the step of forming a quantum dot film includes: drying the quantum dot solution to form a quantum dot film. When the mass ratio of fluorine-containing organic ligands to quantum dot materials is 5% to 15%, it can ensure that the fluorine-containing organic ligand precursor is uniformly dispersed in the quantum dot solution, and the quantum dot material and the fluorine-containing organic ligands fully exchange the fluorine-containing organic ligands, thereby making the fluorine element in the final quantum dot film evenly distributed, thereby improving the uniformity of the liquid-repellent properties of the quantum dot film. As above, the mass ratio of fluorine-containing polymers to quantum dot materials is 2% to 15%, which can make the fluorine-containing polymers themselves evenly distributed in the final quantum dot film, thereby improving the uniformity of the liquid-repellent properties of the quantum dot film. It is understood that the mass ratio of the fluorine-containing polymer to the quantum dot material can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%. The mass ratio of the fluorine-containing organic ligand to the quantum dot material can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0077] Furthermore, when the fluorine-containing material includes a fluorine-containing organic ligand, the fluorine-containing organic ligand includes at least one of a fluorine-containing fatty thiol, a fluorine-containing fatty acid, a fluorine-containing fatty amine, a fluorine-containing fatty alcohol, and a fluorine-containing aromatic hydrocarbon.

[0078] The second solvent includes at least one of C5-C12 alkanes, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO and ether; and / or,

[0079] The fluorine-containing polymers include one or a combination of polytetrafluoroethylene, poly(chlorotrifluoroethylene), poly(vinylidene fluoride), ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, poly(vinyl fluoride), tetrafluoroethylene / perfluoroalkyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, fluorine-containing polyimide, and perfluoropolyether

[0080] At this time, the second solvent itself is a non-polar solvent, and the above-mentioned fluorine-containing organic ligand can be fully dissolved in the non-polar solvent. Therefore, when preparing the electron transport layer on the quantum dots prepared in the embodiments of the present application, the electron transport layer solution usually contains a polar solvent and can be orthogonal to the quantum dot solution of the embodiments of the present application. At this time, it is possible to avoid the mutual dissolution of the electron transport layer solution and the quantum dot solution (or quantum dot film), thereby improving the optical display effect of the finally formed light-emitting device.

[0081] It can be understood that the fluorine-containing polymer is a high-molecular compound, and its molecular chain is usually long. When the fluorine-containing polymer is mixed with the quantum dot material, the long molecular chain of the fluorine-containing polymer can wrap or disperse around the quantum dot material, thereby maintaining the uniformity of the mixture and enabling the fluorine-containing polymer to be uniformly distributed throughout the quantum dot film in a mixed form. Therefore, this embodiment can effectively avoid the stratification of fluorine elements in the quantum dot film, resulting in the loss of electrons and energy at the interface, thereby improving the device service life of the quantum dot film.

[0082] Further, please refer to Figure 3 , the method for preparing the quantum dot film further includes the following steps: performing CF4 plasma treatment on the quantum dot film. At this time, the steps of the method for preparing the quantum dot film are as follows:

[0083] S100, providing a quantum dot solution including a quantum dot material and a second solvent,

[0084] S200, performing a drying treatment on the quantum dot solution to form a prefabricated film;

[0085] S300, performing CF4 plasma treatment on the quantum dot film.

[0086] Because the quantum dot film is treated by the CF4 plasma treatment process, at least the surface of the quantum dot film contains fluorine elements. Therefore, this embodiment can effectively avoid the stratification of fluorine elements in the quantum dot film, resulting in the loss of electrons and energy at the interface, thereby improving the device service life of the quantum dot film.

[0087] It can be understood that the processing power of the plasma treatment can be 0.5 Kw to 5 Kw, and the processing time can be 10 s to 45 s. Both the processing power and the processing time can affect the performance of the quantum dot thin film. The processing power and the processing time of this embodiment can improve the efficiency of CF4 plasma treatment while ensuring the integrity and performance of the quantum dot thin film.

[0088] Further, the quantum dot material includes group II-VI compound semiconductors and their core-shell structures, group III-V or IV-VI compound semiconductors and their core-shell structures; group II-VI semiconductor compounds include at least one of CdSe, CdTe, CdO, CdS, ZnSe, HgO, HgS, HgSe, CdSeS, CdSeTe, CdSTe, CdZnS, CdZnSe, SiSeTe, HgSeS, HgSTe, HgSiS, HgSeSe, CdZnSeTe, HgSiSTe, HgSiSeS; and / or, group III-V semiconductor compounds include at least one of A1N, AlP, AlAs, AlSb, GaN, GaP, A1NP, AlNAs, AlNSb, AlPAs, AlPSb, GaNP, GaNAs, GaPAs, GaPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNAs, GaAlN, GaAlPAs, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP; and / or, group IV-VI semiconductor compounds include at least one of SnSe, SnTe, PbSe, PbS, PbTe, SnSeS, SnSeTe, SnSTe, SnPbS, SnPbSe, SnPbTe, PbSTe, PbSeS, PbSeTe, SnPbSSe, SnPbSeTe, SnPbSTe; and / or, the core-shell diameter of the quantum dot material is 5 nm to 20 nm.

[0089] When a fluorine-containing organic ligand is used to make the quantum dot film contain fluorine, the quantum dot material usually needs to have a core-shell structure so that the fluorine-containing organic ligand can be paired. The core-shell diameter can adjust the energy band structure of the quantum dot film. A larger core-shell diameter usually causes a red shift of the fluorescence emission peak, while a smaller core-shell diameter usually causes a blue shift of the fluorescence emission peak, thereby affecting the optical display effect of the quantum dot film. The average particle size of the quantum dot material in this embodiment is 5 nm to 20 nm, so the emission wavelength and spectral properties of the quantum dot film can be limited within the range required by the light-emitting device to meet the needs of specific applications. It can be understood that the core-shell diameter includes any value among 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm or the range formed by any two values. The quantum dot material may specifically include any one or a combination of CdS, CdSe, CdS / ZnS, CdSe / ZnS, CdSe / CdS / ZnS, GaAs, InP, PbS / ZnS, PbSe / ZnS.

[0090] It can be understood that when the fluorine-containing material of the present application only includes fluorine-containing polymers, the quantum dot material can also be a perovskite semiconductor. The perovskite semiconductor includes one or more of doped inorganic perovskite semiconductors, undoped inorganic perovskite semiconductors, and organic-inorganic hybrid perovskite semiconductors. The structural general formula of the inorganic perovskite semiconductor is AMX3, and the structural general formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where A is a Cs+ ion, B is an organic amine cation, the organic amine cation includes CH3(CH2)n-2NH3+(n≥2) or NH3(CH2)nNH32+(n≥2), M is a divalent metal cation, the divalent metal cation includes one of Pb2+, Sn2+, Cu2+, Ni2+, Cd2+, Cr2+, Mn2+, Co2+, Fe2+, Ge2+, Yb2+, Eu2+, and X is a halogen anion, and the halogen anion includes at least one of Cl-, Br-, I-.

[0091] Correspondingly, the present application also provides a quantum dot film, and the film is prepared by using the preparation method of the above-mentioned quantum dot film. Since the quantum dot film includes a fluorine-containing material and fluorine atoms can reduce the surface energy of the quantum dot film, the quantum dot film of this embodiment has a liquid-repellent property.

[0092] Furthermore, the thickness of the quantum dot thin film is 10 nm to 200 nm; and / or when the quantum dot thin film includes a fluorine-containing polymer, the fluorine-containing polymer and the quantum dot material exist in the quantum dot thin film in a mixed manner. When the thickness of the quantum dot thin film is 10 nm to 200 nm, the wavelength and color purity of the light emitted by the quantum dot thin film can be optimized to meet the application requirements of different light color rays. When the fluorine-containing polymer and the quantum dot material exist in the quantum dot thin film in a mixed manner, the fluorine-containing polymer can be evenly distributed throughout the quantum dot thin film, thereby effectively avoiding the loss of electrons and energy at the interface caused by the stratification of fluorine elements in the quantum dot thin film, and further improving the service life of the quantum dot thin film.

[0093] Correspondingly, please refer to Figure 4 , the present application further provides a light-emitting device, which includes a first electrode 100, a hole functional layer 200, a light-emitting layer 300, an electron functional layer 400, and a second electrode 500 that are sequentially stacked;

[0094] The light-emitting layer 300 is prepared by using the quantum dot thin film preparation method of any one of the above, or uses the quantum dot thin film of any one of the above. Since the light-emitting layer 300 of the light-emitting device includes a fluorine-containing material, it is possible to avoid damage to the hole functional layer 200 when the solution of the electron transport layer 400 passes through the light-emitting layer and enters the hole functional layer during the preparation of the electron transport layer 400, thereby improving the service life of the light-emitting device. It can be understood that the first electrode 100 and the second electrode 500 are usually an anode and a cathode. The hole functional layer 200 may include a hole injection layer and / or a hole transport layer, and the electron functional layer 400 includes an electron injection layer and / or an electron functional layer.

[0095] The materials of the first electrode 100 and the second electrode 500 include at least one of a metal, a carbon material, and a metal oxide. The metal includes at least one of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes at least one of graphite, carbon nanotubes, graphene, and carbon fiber; the metal oxide includes a doped or undoped metal oxide, including at least one of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO; and / or,

[0096] The materials of the hole functional layer 200 include at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, T·APC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal stannides, doped graphene, undoped graphene, and C60; and / or,

[0097] The materials of the electronic functional layer 400 include inorganic materials and / or organic materials; the inorganic materials are selected from at least one of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, aluminum zinc oxide, manganese zinc oxide, tin zinc oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc stannide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate; the doping elements include at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, gadolinium; the organic materials are selected from at least one of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds.

[0098] The following specific examples are used to specifically illustrate the present application. The following examples are only part of the embodiments of the present application and do not limit the present application.

[0099] Example 1

[0100] This example provides a preparation method of a light-emitting device. The preparation method is as follows:

[0101] Step 1, prepare the anode. Place the ITO glass in a glass dish containing ethanol solution, wipe the ITO glass clean with a cotton swab, and perform ultrasonic treatment with acetone, deionized water, and ethanol in sequence, with each ultrasonic treatment time of 10 min; dry the ITO glass with a nitrogen gun, place the ITO glass in an oxygen plasma for cleaning, with the cleaning time of 10 min; put the ITO glass into a vacuum dust-free oven for baking, with the baking temperature of 240 °C and the baking time of 30 min to form the anode.

[0102] Step 2, prepare the hole injection layer. Spin-coat or ink-jet print the hole injection layer solution on the anode in air, with the spin-coating speed of 2300 r / min and the spin-coating time of 35 s; perform drying treatment, with the drying environment of 10000 Pa pressure and the drying time of 5 min to form the hole injection layer.

[0103] Step 3, prepare the hole transport layer. Spin-coat or ink-jet print the hole transport layer solution on the above hole injection layer, with the spin-coating speed of 2000 r / min and the spin-coating time of 40 s; perform drying treatment, with the drying environment of 10000 Pa pressure and the drying time of 5 min; to form the hole transport layer.

[0104] Step 4, prepare the prefabricated film. Spin-coat the quantum dot solution on the above hole transport layer, with the spin-coating speed of 1600 r / min and the spin-coating time of 30 s; perform drying treatment, with the drying environment of 10000 Pa pressure and the drying time of 5 min to form the prefabricated film, and the quantum dot solution is composed of CdSe and n-hexane.

[0105] Step 5, preparing the quantum dot thin film. Immerse the above-prepared thin film in a fluorine-containing treatment solution for 10 min at a soaking temperature of 10°C; perform annealing treatment at an annealing temperature of 100°C for 15 min to form a quantum dot thin film. The materials of the fluorine-containing treatment solution include carbon tetrachloride and trifluoroethyl mercaptan.

[0106] Step 6, preparing the electron transport layer. Spin-coat or inkjet-print the electron transport layer solution on the above light-emitting layer at a spin-coating speed of 3400 r / min for 40 s; perform drying treatment in a drying environment with a pressure of 10000 Pa for 5 min to form an electron transport layer. The solvent of the electron transport layer is carbon tetrachloride.

[0107] Step 7, preparing the cathode layer and the capping layer. Transfer the above electron transport layer to a high-vacuum evaporation device or a sputtering device, and deposit the cathode and the capping layer at a pressure of 8 Pa. The deposition rate of the cathode is 22 Å / s (angstroms per second), and the deposition rate of the capping layer is 1.52 Å / s to form the cathode and the capping layer.

[0108] Step 8, encapsulation. Use an encapsulation adhesive and an encapsulation cover plate to encapsulate the above light-emitting device, encapsulate the light-emitting device with an ultraviolet curable resin (Pulse Puretone 20-001), and store it in an N2 environment.

[0109] Example 2

[0110] This example is basically the same as Example 1, except that: Step 4 and Step 5 are replaced by Step A, and Step A includes:

[0111] Providing a quantum dot solution; mixing and stirring CdSe, chloroform, and trifluoroethyl mercaptan to form a quantum dot solution. Spin-coat the quantum dot solution on the above hole transport layer and perform drying treatment in a drying environment with a pressure of 10000 Pa for 5 min to form a quantum dot thin film.

[0112] Example 3

[0113] This example is basically the same as Example 2, except that: trifluoroethyl mercaptan is replaced by polyvinylidene fluoride.

[0114] Example 4

[0115] This example is basically the same as Example 1, except that: the content of Step 5 is replaced by "performing CF4 plasma treatment on the prepared quantum dot thin film with a power of 2 Kw for 30 s to form a quantum dot thin film with a fluorine-containing surface".

[0116] Example 5

[0117] This example is basically the same as Example 2, except that: trifluoroethanethiol is replaced by perfluorooctylamine.

[0118] Example 6

[0119] This example is basically the same as Example 2, except that: trifluoroethanethiol is replaced by perfluorodimercaptopropanol.

[0120] Example 7

[0121] This example is basically the same as Example 2, except that: trifluoroethanethiol is replaced by hexafluorobenzene.

[0122] Example 4

[0123] This example is basically the same as Example 2, except that: trifluoroethanethiol is replaced by trifluoroacetic acid.

[0124] Comparative Example 1

[0125] This comparative example is basically the same as Example 2, except that: trifluoromethylthiol is omitted.

[0126] Comparative Example 2

[0127] This comparative example is basically the same as Example 2, except that: trifluoromethylthiol is replaced by zinc tetrafluoride, chloroform is replaced by acetone; the electron transport layer solution includes xylene.

[0128] Comparative Example 3

[0129] This comparative example is basically the same as Example 3, except that: trifluoromethylthiol is replaced by NDI (N,N-bis(2,2,3,3,4,4,4-heptafluorobutyl-)-1,4,5,8-naphthalene-tetracarboxylic diimide).

[0130] The light-emitting device performance of Examples 1 to 3 and Comparative Examples 1 to 3 was tested using an IVL device. The voltage at a current density of 10 mA / cm2 (J10) was used as the driving voltage index, and the time when the brightness decayed to 95% under a constant current condition at an initial brightness of 1000 nit was used as the light-emitting device lifetime evaluation index. Taking the lifetime length of Comparative Example 1 as the base number (100%), the lifetime lengths of the other comparative examples and examples were respectively compared with that of Comparative Example 1, and the percentage of the comparison result was taken. The test results are shown in Table 1.

[0131] Table 1:

[0132]

[0133]

[0134] According to the test results of Comparative Example 1 and Examples 1 to 4, the method for preparing a quantum dot thin film provided by the embodiments of the present application can increase fluorine elements in the quantum dot thin film, thereby improving the service life of a light-emitting device having the quantum dot thin film.

[0135] According to Examples 2 and 5 to 8, the material of the fluorine-containing ligand can be selected from at least one of fluorinated aliphatic thiols, fluorinated fatty acids, fluorinated aliphatic amines, fluorinated aliphatic alcohols, and fluorinated aromatic hydrocarbons.

[0136] According to Examples 1 and 2, compared with the scheme of performing ligand exchange treatment on the prefabricated thin film after forming the prefabricated thin film, the scheme of adding a fluorine-containing organic ligand in advance in the quantum dot solution can enable the quantum dot material to fully perform ligand exchange with the fluorine-containing organic ligand, thereby improving the service life of the finally formed quantum dot thin film.

[0137] According to Example 2 and Comparative Example 2, when preparing a quantum dot solution using a fluorine-containing inorganic ligand, the solvent of the quantum dot solution is a polar solvent such as acetone, and the solvent in the electron transport layer solution, such as xylene, is also a polar solvent. At this time, the solution of the electron transport layer and the quantum dot solution will dissolve and disperse, resulting in a smaller increase in the service life of the light-emitting device.

[0138] According to Example 3 and Comparative Example 3, when preparing a quantum dot solution using a fluorine-containing small molecule, since the fluorine-containing polymer can be uniformly formed and mixed in the quantum dot solution, it is possible to avoid the bilayer structure of the formed quantum dot layer / fluorine-containing small molecule layer (having insulating properties) from affecting the electron transport of the light-emitting device, thereby improving the service life of the light-emitting device.

[0139] In summary, the method for preparing a quantum dot thin film according to the embodiments of the present application can improve the service life of a light-emitting device.

[0140] The above has introduced in detail the quantum dot thin film, its preparation method, and the light-emitting device provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, based on the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0141] Obviously, the embodiments described above are only a part of the embodiments of this application, rather than all of them. The preferred embodiments of this application are shown in the drawings, but do not limit the patent scope of this application. This application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of this application more thorough and comprehensive. Although this application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements for some of the technical features. Any equivalent structure made by using the content of this application's specification and drawings, directly or indirectly applied in other related technical fields, is similarly within the scope of patent protection of this application.

[0142] Although the embodiments of this application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, combinations, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of this application. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a quantum dot film, characterized in that: The method comprises: A quantum dot solution including a quantum dot material and a second solvent is provided, and the second solvent in the quantum dot solution is volatilized to form a quantum dot film; wherein the material of the quantum dot film includes the quantum dot material and fluorine element.

2. The method for preparing a quantum dot thin film according to claim 1, characterized in that: The step of volatilizing the second solvent in the quantum dot solution to form a quantum dot film comprises: Drying the quantum dot solution to form a prefabricated film; Performing a ligand exchange treatment on the prefabricated film using a fluorine-containing organic ligand to form a quantum dot film containing fluorine element; Optionally, the fluorine-containing organic ligand includes at least one of fluorine-containing fatty thiol, fluorine-containing fatty acid, fluorine-containing fatty amine, fluorine-containing fatty alcohol, and fluorine-containing aromatic hydrocarbon.

3. The method for preparing a quantum dot thin film according to claim 2, characterized in that: The step of performing ligand exchange treatment on the prefabricated film with a fluorine-containing organic ligand comprises: Providing a fluorine-containing treatment liquid, wherein the fluorine-containing treatment liquid comprises a fluorine-containing organic ligand and a first solvent; The prefabricated film is immersed in a fluorine-containing treatment solution for 10 to 30 minutes at a temperature of 10° C. to 25° C.; One of the first solvent and the second solvent is a polar solvent, and the other is a non-polar solvent; Optionally, the fluorinated organic ligand is selected from at least one of trifluoromethylmercaptan, trifluoroethanethiol, trifluoroacetic acid, perfluorooctylamine, trifluoromethylamine, trifluoromethanol, perfluorodimercaptopropanol, hexafluorobenzene, and fluorinated catechol; and / or, The first solvent includes at least one of C5-C12 alkanes, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO and diethyl ether, and the second solvent includes at least one of C5-C12 alkanes, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO and diethyl ether; and / or, The mass ratio of the fluorine-containing organic ligand to the first solvent is 1:5 to 1:20; And / or, the concentration of the quantum dot material in the quantum dot solution is 5 mg / ml to 50 mg / ml.

4. The method for preparing a quantum dot thin film according to claim 1, characterized in that: Before the step of providing a quantum dot solution including a quantum dot material and a second solvent, the step further includes: Providing a quantum dot material, a second solvent, and a fluorine-containing material; wherein the fluorine-containing material comprises a fluorine-containing organic ligand and / or a fluorine-containing polymer; The quantum dot material, the second solvent, and the fluorine-containing material are mixed to form the quantum dot solution.

5. The method for preparing a quantum dot thin film according to claim 4, characterized in that: If the fluorine-containing material is composed of a fluorine-containing organic ligand, the mass ratio of the fluorine-containing organic ligand to the quantum dot material in the quantum dot solution is 5% to 15%; or, if the fluorine-containing material is composed of a fluorine-containing polymer, the mass ratio of the fluorine-containing polymer to the quantum dot material in the quantum dot solution is 2% to 15%; and / or, The step of volatilizing the second solvent in the quantum dot solution to form a quantum dot film includes: drying the quantum dot solution to form a quantum dot film.

6. The method for preparing a quantum dot thin film according to claim 4, characterized in that: The fluorine-containing organic ligand is selected from at least one of trifluoromethylmercaptan, trifluoroethanethiol, trifluoroacetic acid, perfluorooctylamine, trifluoromethylamine, trifluoromethanol, perfluorodimercaptopropanol, hexafluorobenzene, and fluorine-containing catechol; and / or, The second solvent comprises at least one of C5-C12 alkanes, chloroform, dichloromethane, carbon tetrachloride, benzene, toluene, xylene, acetone, DMF, DMSO and ether; and / or, The fluorine-containing polymer includes one of polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, polyvinyl fluoride, tetrafluoroethylene / perfluoroalkyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / ethylene copolymer, fluorine-containing polyimide, and perfluoropolyether, or a combination thereof.

7. The method for preparing a quantum dot thin film according to claim 1, characterized in that: The preparation method further comprises the following steps: subjecting the quantum dot film to CF4 plasma treatment.

8. The method for preparing a quantum dot film according to claims 1-7, characterized in that: The quantum dot materials include II-VI group compound semiconductors and their core-shell structures, III-V or IV-VI group compound semiconductors and their core-shell structures; The II-VI Group semiconductor compound includes at least one of CdSe, CdTe, CdO, CdS, ZnSe, HgO, HgS, HgSe, CdSeS, CdSeTe, CdSTe, CdZnS, CdZnSe, SiSeTe, HgSeS, HgSTe, HgSiS, HgSeSe, CdZnSeTe, HgSiSTe, and HgSiSeS; and / or, The III-V Group semiconductor compound includes at least one of AlN, AlP, AlAs, AlSb, GaN, GaP, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, GaNP, GaNAs, GaPAs, GaPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNAs, GaAlN, GaAlPAs, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, and InAlNP; and / or, The IV-VI Group semiconductor compound includes at least one of SnSe, SnTe, PbSe, PbS, PbTe, SnSeS, SnSeTe, SnSTe, SnPbS, SnPbSe, SnPbTe, PbSTe, PbSeS, PbSeTe, SnPbSSe, SnPbSeTe, SnPbSTe; and / or, The average particle size of the quantum dot material is 5nm to 20nm.

9. A quantum dot film, characterized in that: The film is prepared by the method for preparing a quantum dot film according to any one of claims 1 to 8.

10. A light-emitting device, comprising a light-emitting layer, characterized in that: The light-emitting layer is prepared by the method for preparing a quantum dot film according to any one of claims 1 to 8, or by the quantum dot film according to claim 9.

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