Thin film and preparation method thereof, light-emitting device and display device
By adopting the thin film preparation method in QLED devices and using a mixed solvent atmosphere to treat the inorganic nano film, the problem of insufficient film formation uniformity and density of the quantum dot luminescent layer is solved, and the luminescence efficiency of the luminescent device is significantly improved.
Patent Information
- Application Number
- CN202311571211.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-05-23
AI Technical Summary
In existing QLED devices, the film formation uniformity and density of the quantum dot luminescent layer are poor, resulting in a large surface roughness and affecting the luminescent performance.
By adopting a thin film preparation method, solvent volatilization and solvent annealing are performed by providing a mixed solution of inorganic nanomaterials and solvents, the film formation uniformity and density of the inorganic nanofilm are improved by using the mixing atmosphere of the first solvent and the second solvent.
It effectively improves the film formation uniformity and density of the film, reduces the surface roughness, and thus improves the luminous efficiency of the light emitting device.
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Figure CN120035356A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of display technology, and more specifically, to a method for preparing a thin film, a thin film, a light-emitting device, and a display apparatus. Background Art
[0002] QLED (Quantum Dots Light-Emitting Diode) devices, which use inorganic quantum dots as electroluminescent materials, have the advantages of wide color gamut coverage, high color purity, ultra-thin and light, and bendable and curlable, and therefore have received extensive attention from academia and industry. QLED devices are usually prepared by a solution method, that is, the functional layer solutions are printed and coated on a substrate with an anode attached in sequence and dried to form a film, thereby forming a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and an electron injection layer in sequence, and finally forming a cathode by evaporation or sputtering to form a complete light-emitting device.
[0003] For QLED devices, the film formation uniformity and density of the quantum dot light-emitting layer prepared by conventional preparation methods are poor, resulting in a large surface roughness of the quantum dot light-emitting layer, which has a great impact on the light-emitting performance of the light-emitting device. Summary of the invention
[0004] The present application aims to provide a method for preparing a thin film.
[0005] The present invention provides a method for preparing a thin film, which adopts the following technical solution:
[0006] A method for preparing a thin film comprises the following steps:
[0007] Providing a mixed solution including an inorganic nanomaterial and a solvent;
[0008] Treating the mixed solution to volatilize the solvent in the mixed solution, thereby obtaining an inorganic nanofilm including inorganic nanomaterials;
[0009] Placing the inorganic nanofilm in an atmosphere chamber for solvent annealing to obtain the film;
[0010] A solvent atmosphere of a mixed solvent is formed in the atmosphere chamber, wherein the mixed solvent includes a first solvent and a second solvent, the solubility of the first solvent in the inorganic nanomaterial is greater than 20 mg / ml, and the solubility of the second solvent in the inorganic nanomaterial is less than 3 mg / ml.
[0011] Furthermore, the step of treating the mixed solution includes placing the mixed solution in a static state at a temperature of 25° C. to 30° C.;
[0012] And / or, the time for the static treatment is 1 min to 10 min;
[0013] and / or, the temperature during solvent annealing is 10° C. to 50° C.;
[0014] And / or, the solvent annealing treatment is performed for 10 minutes to 3 hours.
[0015] Further, the boiling point of the first solvent is less than or equal to 150°C, and the boiling point of the second solvent is less than or equal to 150°C;
[0016] and / or, the absolute value of the difference between the boiling point of the first solvent and the boiling point of the second solvent is less than or equal to 40° C.;
[0017] And / or, the volume ratio of the first solvent to the second solvent is in the range of (1:10) to (10:1).
[0018] Further, the inorganic nanomaterial includes a quantum dot material, the quantum dot material includes at least one of a single structure quantum dot and a core-shell structure quantum dot, the material of the single structure quantum dot, the core material and the shell material of the core-shell structure quantum dot are independently selected from at least one of a II-VI group compound, a IV-VI group compound, a III-V group compound and a I-III-VI group compound, the shell layer of the core-shell structure quantum dot includes one or more layers, wherein the II-VI group compound includes CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, Hg Se, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, H At least one of gZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, IV-VI The group III-V compounds include at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, and the group III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, At least one of GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound is, but is not limited to, CuInS 2 、CuInSe 2 AgInS 2 At least one of .
[0019] Further, at least part of the inorganic nanomaterials further comprises a hydrophobic ligand connected to the surface thereof, wherein the hydrophobic ligand comprises at least one of substituted or unsubstituted C6-C24 fatty acids, substituted or unsubstituted C6-C24 fatty amines, substituted or unsubstituted C6-C24 aliphatic thiols, substituted or unsubstituted C6-C24 aliphatic sulfides, substituted or unsubstituted C6-C24 aliphatic phosphines, substituted or unsubstituted C6-C24 aliphatic phosphine oxides, substituted or unsubstituted C8-C20 aliphatic phosphoric acids, substituted or unsubstituted C6-C24 aliphatic phosphates, substituted or unsubstituted C6-C24 aliphatic phosphorous acids, and substituted or unsubstituted C6-C24 aliphatic phosphites, and the substituted substituents are selected from at least one of C1-C6 alkyls, C1-C6 alkoxys, and halogens;
[0020] Optionally, the fatty acid includes at least one of capric acid, undecylenic acid, tetradecanoic acid, oleic acid, linoleic acid, and stearic acid;
[0021] Optionally, the aliphatic mercaptan includes at least one of octyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan;
[0022] Optionally, the fatty amine includes at least one of oleylamine, octadecylamine, octylamine, dioctylamine and trioctylamine;
[0023] Optionally, the (oxygen) phosphine ligand includes at least one of trioctylphosphine, trioctylphosphine oxide
[0024] And / or, the average particle size of the quantum dot material is 6nm to 13nm;
[0025] and / or, the solvent comprises at least one of n-octane, benzene, toluene, cyclohexane, hexane, and cyclooctane;
[0026] and / or, the first solvent comprises at least one of chloroform, benzene, toluene, xylene, hexane, heptane, and octane;
[0027] And / or, the second solvent includes at least one of methanol, ethanol, propanol, butanol, ethyl acetate and acetone.
[0028] Furthermore, before the step of placing the inorganic nanofilm in an atmosphere chamber for solvent annealing, the following steps are also included:
[0029] The mixed solvent is injected into the atmosphere chamber and allowed to stand, and the temperature in the atmosphere chamber is adjusted to a set temperature.
[0030] Furthermore, the stationary time of the mixed solvent in the atmosphere chamber ranges from 2h to 3h;
[0031] And / or, the set temperature ranges from 25°C to 50°C.
[0032] The present application also provides a thin film, which adopts the following technical solution:
[0033] A film is prepared by the above film preparation method.
[0034] The present application also provides a light emitting device, which adopts the following technical solution:
[0035] A light emitting device, comprising:
[0036] An anode layer and a cathode layer are arranged opposite to each other;
[0037] The light-emitting layer is prepared by the thin film preparation method according to any one of claims 1 to 7, and the light-emitting layer is arranged between the anode layer and the cathode layer.
[0038] The present application also provides a display device, which adopts the following technical solution:
[0039] A display device, characterized in that the display device comprises the light-emitting device as described above.
[0040] Compared with the prior art, the embodiments of the present application have the following beneficial effects:
[0041] The present invention improves the film formation uniformity / density of the thin film and has the effect of improving the surface roughness of the thin film. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] In order to more clearly illustrate the scheme of the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0043] Figure 1 is a flow chart of a method for preparing a thin film according to an embodiment of the present application;
[0044] Figure 2 It is a schematic diagram of the structure of the light-emitting device of an embodiment of the present application.
[0045] Reference numerals:
[0046] 1. Anode layer; 2. Hole functional layer; 21. Hole injection layer; 22. Hole transport layer; 3. Light-emitting layer; 4. Electron transport layer; 5. Cathode layer. DETAILED DESCRIPTION
[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.
[0048] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0049] For conventional QLED devices, due to the limitations of quantum dot material properties, the thickness of the quantum dot light-emitting layer is relatively thin, usually formed by stacking no more than 5 layers of quantum dot nanoparticles, with a thickness of no more than 50nm. The thickness uniformity and density of the film have a great impact on the luminescence performance of the device.
[0050] The conventional preparation method of the quantum dot light-emitting layer is to form an initial quantum dot film using a solution method for the quantum dot material, and then perform a thermal annealing treatment on the initial quantum dot film to form a quantum dot light-emitting layer. The quantum dot light-emitting layer formed by the conventional preparation method has a relatively large surface roughness due to insufficient film uniformity and film density.
[0051] In areas where the quantum dot light-emitting layer is thin, it is easy for the upper and lower functional layers to directly contact each other through the stacking gap of the quantum dot particles, forming leakage current and causing a decrease in current efficiency. In areas where the quantum dot light-emitting layer is thicker, the current is significantly smaller than in other areas, making the actual light-emitting area smaller than the pixel area, and the light emission of the quantum dot light-emitting layer is uneven, ultimately affecting the current efficiency of the light-emitting device. Therefore, the uniformity and density of the film formation of the quantum dot light-emitting layer is one of the key links in improving the light-emitting performance of the light-emitting device.
[0052] See also Figure 1 As shown, the embodiment of the present application provides a method for preparing a thin film, comprising the following steps:
[0053] Step S100, providing a mixed solution including an inorganic nanomaterial and a solvent;
[0054] Step S200, treating the mixed solution to volatilize the solvent in the mixed solution to obtain an inorganic nanofilm including inorganic nanomaterials;
[0055] Step S300, placing the inorganic nanofilm in an atmosphere chamber for solvent annealing to obtain the film.
[0056] A solvent atmosphere of a mixed solvent is formed in the atmosphere chamber, wherein the mixed solvent includes a first solvent and a second solvent, the solubility of the first solvent in the inorganic nanomaterial is greater than 20 mg / ml, and the solubility of the second solvent in the inorganic nanomaterial is less than 3 mg / ml.
[0057] In the embodiment of the present application, inorganic nanomaterials are prepared into inorganic nanofilms and placed in an atmosphere chamber filled with a mixed solvent atmosphere, so that the surface of the inorganic nanofilm is exposed to the mixed solvent atmosphere of the first solvent and the second solvent, and solvent annealing treatment is performed in the mixed solvent atmosphere. The first solvent atmosphere enables the inorganic nanomaterials in the film to have a certain ability to migrate and rearrange; the second solvent atmosphere promotes the stacking of the inorganic nanomaterials in the film to be more dense, which reduces the contact area between the inorganic nanomaterials and the second solvent, thereby reducing the overall surface energy, improving the film formation uniformity and density of the film, and improving the surface roughness of the film.
[0058] In this embodiment, in step S200, the mixed solution is treated to volatilize the solvent in the mixed solution to obtain an inorganic nanofilm including inorganic nanomaterials, which specifically includes the following steps:
[0059] The mixed solution is formed into an inorganic nano liquid film by a solution method.
[0060] In this embodiment, the solvent method may be one of spin coating, inkjet printing or doctor blade coating.
[0061] The inorganic nano liquid film is subjected to a static treatment under negative pressure conditions to obtain the inorganic nano thin film.
[0062] In some embodiments, the negative pressure is set in the range of 1×10 -5 ~1×10 -4 Pa. In this embodiment, the set negative pressure can be set to 1×10 -5 Pa, 2×10 -5 Pa, 3×10 -5 Pa, 4×10 -5 Pa, 5×10 -5 Pa, 6×10 -5 Pa, 7×10 -5 Pa, 8×10 -5Pa, 9×10 -5 Pa, 1×10 -5 Any value or the range formed between any two values in Pa.
[0063] In some embodiments, the temperature during the static treatment is 25°C to 30°C. In this embodiment, the temperature of the static treatment can be set to any value of 25°C, 26°C, 27°C, 28°C, 29°C, 30°C or a range formed between any two values.
[0064] In some embodiments, the time for the static treatment is 1 min to 10 min. In this embodiment, the duration of the static treatment can be set to any one of 1 min, 5 min, 10 min or a range formed between any two values.
[0065] In the process of preparing inorganic nanofilms using inorganic nanomaterials, the embodiments of the present application set negative pressure conditions to help discharge gas in the inorganic nano liquid film and avoid the generation of bubbles during the preparation process, thereby improving the film formation uniformity of the inorganic nano film, and appropriate negative pressure can form an inorganic nano liquid film with better uniformity.
[0066] In some embodiments, the inorganic nanomaterial includes a quantum dot material, the quantum dot material includes at least one of a single structure quantum dot and a core-shell structure quantum dot, the material of the single structure quantum dot, the core material and the shell material of the core-shell structure quantum dot are independently selected from at least one of a II-VI group compound, a IV-VI group compound, a III-V group compound and a I-III-VI group compound, wherein the II-VI group compound includes CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, Cd At least one of SeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI compounds include SnS, S At least one of nSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, and III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb , AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound is, but is not limited to, CuInS 2 、CuInSe 2 AgInS 2 At least one of .
[0067] In this embodiment, the inorganic nanomaterial is an oil-soluble quantum dot, and at least part of the inorganic nanomaterial also includes a hydrophobic ligand connected to its surface, wherein the hydrophobic ligand includes at least one of substituted or unsubstituted C6-C24 fatty acids, substituted or unsubstituted C6-C24 fatty amines, substituted or unsubstituted C6-C24 aliphatic thiols, substituted or unsubstituted C6-C24 aliphatic sulfides, substituted or unsubstituted C6-C24 aliphatic phosphines, substituted or unsubstituted C6-C24 aliphatic phosphine oxides, substituted or unsubstituted C8-C20 aliphatic phosphoric acids, substituted or unsubstituted C6-C24 aliphatic phosphates, substituted or unsubstituted C6-C24 aliphatic phosphorous acids, and substituted or unsubstituted C6-C24 fatty phosphites, and the substituted substituents are selected from at least one of C1-C6 alkyl, C1-C6 alkoxy, and halogen.
[0068] Optionally, the fatty acid includes at least one of capric acid, undecylenic acid, tetradecylic acid, oleic acid, linoleic acid, and stearic acid;
[0069] Optionally, the aliphatic mercaptan includes at least one of octyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan;
[0070] Optionally, the fatty amine includes at least one of oleylamine, octadecylamine, octylamine, dioctylamine and trioctylamine;
[0071] Optionally, the (oxygen) phosphine ligand includes at least one of trioctylphosphine and trioctylphosphine oxide.
[0072] In this embodiment, the inorganic nanomaterial consists of a CdSe core, a CdS shell and an oleic acid ligand.
[0073] In some embodiments, the average particle size of the quantum dot material is 6nm to 13nm. Specifically, the average particle size of the quantum dot material can be set to any value of 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm or a range formed between any two values.
[0074] In some embodiments, the solvent includes at least one of n-octane, benzene, toluene, cyclohexane, hexane, and cyclooctane.
[0075] In some embodiments, a placement groove and a solvent groove are provided in the atmosphere cavity in step S300, wherein the placement groove is used to place the inorganic nanofilm prepared in step S200, and the solvent groove is used to contain the mixed solvent. The opening area of the placement groove and the opening area of the solvent groove are added together to obtain the total area of the atmosphere cavity. In this embodiment, the opening area of the solvent groove is not less than one fifth of the total area of the atmosphere cavity, so that the mixed solvent can form a solvent atmosphere of sufficient concentration after sufficient evaporation.
[0076] In some embodiments, the height of the atmosphere chamber does not exceed 10 cm, so as to maintain a stable concentration of the mixed solvent atmosphere in the atmosphere chamber, so as to form an inorganic nanofilm with uniform film formation and compactness.
[0077] In the embodiment of the present application, the structure of the atmosphere chamber for solvent annealing of the inorganic nanofilm is designed so that the mixed solvent can form a solvent atmosphere of sufficient concentration in the atmosphere chamber after volatilization, thereby improving the effect of the mixed solvent atmosphere on the surface treatment of the inorganic nanofilm.
[0078] In some embodiments, before the step S300 of placing the inorganic nanofilm in an atmosphere chamber for solvent annealing to obtain the film, the step further includes the following steps:
[0079] The mixed solvent is injected into the atmosphere chamber and allowed to stand, and the temperature in the atmosphere chamber is adjusted to a set temperature.
[0080] In some embodiments, the mixed solvent is injected into the solvent tank of the atmosphere chamber, and the mixed solvent is left standing in the solvent tank of the atmosphere chamber for a period of 2 to 3 hours, for example, any one of 2 hours, 2.5 hours, and 3 hours, or a range formed between any two values.
[0081] In some embodiments, the set temperature ranges from 25°C to 50°C. Specifically, after the mixed solvent is injected into the solvent tank, the temperature in the atmosphere chamber is adjusted to any one of 25°C, 30°C, 35°C, 40°C, 45°C, and 50°C or to a range formed between any two values.
[0082] The embodiment of the present application controls the mixed solvent to fully volatilize by injecting the mixed solvent into the solvent tank of the atmosphere chamber in advance and controls the standing time, thereby forming a sufficient solvent atmosphere in the atmosphere chamber so that the first solvent and the second solvent can fully cooperate with the inorganic nanomaterial; in addition, by controlling the temperature in the atmosphere chamber to adapt the combination of the first solvent and the second solvent with different boiling points in the mixed solvent, the volatilization of the mixed solvent formed by the first solvent and the second solvent is further promoted, thereby increasing the concentration of the mixed solvent atmosphere, and further promoting the full cooperation of the mixed solvent with the inorganic nanomaterial.
[0083] In some embodiments, in step S300, the temperature of the solvent annealing treatment of the inorganic nanofilm is 10°C to 50°C. Specifically, the temperature of the solvent annealing treatment can be set to any value of 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or a range formed between any two values.
[0084] In some embodiments, in step S300, the duration of solvent annealing treatment of the inorganic nanofilm is 10 minutes to 3 hours. Specifically, the duration of the solvent annealing treatment can be set to any value of 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours or a range formed between any two values.
[0085] The embodiment of the present application sets the temperature and time of the solvent annealing treatment so that when the inorganic nanofilm is in the atmosphere chamber, the mixed solvent atmosphere can fully treat the surface of the inorganic nanofilm, thereby improving the film formation uniformity and density of the film and improving the surface roughness of the film.
[0086] In some embodiments, the mixed solvent includes a mixed first solvent and a second solvent, wherein the volume ratio of the first solvent to the second solvent ranges from (1:10) to (10:1), for example: (1:1) to (1:10), (10:1) to (1:1).
[0087] In some embodiments, the solubility of the first solvent in the inorganic nanomaterial is greater than 20 mg / mL, and the solubility of the second solvent in the inorganic nanomaterial is less than 3 mg / mL.
[0088] In some embodiments, the boiling point of the first solvent is less than or equal to 150°C, and the boiling point of the second solvent is less than or equal to 150°C.
[0089] In some embodiments, the absolute value of the difference between the boiling point of the first solvent and the boiling point of the second solvent is less than or equal to 40°C, for example: the absolute value of the difference in boiling point is 40°C, the absolute value of the difference in boiling point is 30°C, the absolute value of the difference in boiling point is 20°C, and the absolute value of the difference in boiling point is 10°C.
[0090] In some embodiments, the material of the first solvent includes at least one of chloroform, benzene, toluene, xylene, hexane, heptane, and octane; the material of the second solvent includes at least one of methanol, ethanol, propanol, butanol, ethyl acetate, and acetone.
[0091] In this embodiment, the material of the mixed solvent can be selected from one of the following combinations: n-hexane (boiling point: 68.95°C) / ethanol (boiling point: 78.3°C), n-hexane (boiling point: 68.95°C) / acetone (boiling point: 56.5°C), n-hexane (boiling point: 68.95°C) / n-butanol (boiling point: 117.6°C), n-hexane (boiling point: 68.95°C) / isopropanol (boiling point: 82.5°C), toluene (boiling point: 110.8°C) / ethanol (boiling point: 78.3°C), toluene (boiling point: 110.8°C) / acetone (boiling point: 56.5°C), toluene (boiling point: 110.8°C) / n-butanol (boiling point: 117.6°C), and toluene (boiling point: 110.8°C) / isopropanol (boiling point: 82.5°C).
[0092] Wherein, in the above combination, the first component represents the first solvent, the second component represents the second solvent, and the absolute value of the difference in boiling point between the first solvent and the second solvent is less than or equal to 40°C.
[0093] In some embodiments, after the step S300 of placing the inorganic nanofilm in an atmosphere chamber for solvent annealing to obtain the film, the following steps are further included:
[0094] The film is subjected to a thermal annealing treatment.
[0095] In some embodiments, the temperature range of the thermal annealing treatment of the film is 50°C to 120°C. Specifically, the temperature of the thermal annealing treatment can be set to any one of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or a range formed between any two values.
[0096] In some embodiments, the thermal annealing treatment of the film is performed for 5 to 30 minutes. Specifically, the duration of the thermal annealing treatment can be set to any value of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, and 30 minutes, or a range formed between any two values.
[0097] In the embodiment of the present application, the film that has undergone solvent annealing treatment is further subjected to thermal annealing treatment to remove residual solvent on the surface of the film and further improve the surface roughness of the film.
[0098] An embodiment of the present application also provides a thin film, which is prepared by the above-mentioned thin film preparation method. The thin film is used for the light-emitting layer in the light-emitting device to improve the film formation uniformity and density of the light-emitting layer, thereby achieving the effect of improving the luminous efficiency of the light-emitting device.
[0099] See also Figure 2As shown, an embodiment of the present application further provides a light-emitting device, which contains the above-mentioned film. In some embodiments, the film serves as the light-emitting layer 3 of the light-emitting device.
[0100] In some embodiments, the light emitting device includes an anode layer 1 and a cathode layer 5 which are arranged opposite to each other.
[0101] The light-emitting layer 3 is prepared by the above-mentioned thin film preparation method, and the light-emitting layer 3 is arranged between the anode layer 1 and the cathode layer 5 .
[0102] In some embodiments, the light-emitting device also includes a hole functional layer 2, which is arranged between the anode layer 1 and the light-emitting layer 3. In this embodiment, the hole functional layer 2 includes a stacked hole injection layer 21 and a hole transport layer 22, and the hole injection layer 21 is arranged on the anode layer 1.
[0103] In some embodiments, the light emitting device further comprises the electronic functional layer 4, and the electronic functional layer 4 is disposed between the light emitting layer 3 and the cathode layer 5. In this embodiment, the electronic functional layer 4 comprises an electron transport layer.
[0104] In this embodiment, the light-emitting device is a positive light-emitting device, and the structure of the light-emitting device is anode layer 1 / hole functional layer 2 / light-emitting layer 3 / electron functional layer 4 / cathode layer 5. In other embodiments, the light-emitting device can also be an inverted light-emitting device, and the structure of the light-emitting device is cathode layer 5 / electron functional layer 4 / light-emitting layer 3 / hole functional layer 2 / anode layer 1.
[0105] In some embodiments, the material of the anode layer 1 and / or the cathode layer 5 includes at least one of a metal, a carbon material and a metal oxide, wherein 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, or includes a composite electrode in which a metal is sandwiched between doped or undoped transparent metal oxides, and the composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO 2 / Ag / TiO 2 and TiO 2 / Al / TiO 2 At least one of .
[0106] In some embodiments, the hole functional layer 2 includes a hole injection layer 21 and a hole transport layer 22 which are stacked, and the material of the hole injection layer 21 and / or the hole transport layer 22 includes at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tri(N-3-methylphenyl-Nphenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tinides, doped graphene, undoped graphene and C60.
[0107] In this embodiment, the electronic functional layer 4 includes an electron transport layer, and the material of the electron transport layer includes an inorganic material and / or an organic material. The inorganic material is 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, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate, and the doped element includes at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; the organic material is selected from at least one of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene compounds, and hydroxyquinoline compounds.
[0108] The light-emitting layer 3 of the light-emitting device provided in the embodiment of the present application is prepared by the above-mentioned thin film preparation method, by placing the dried and film-formed inorganic nanofilm in an atmosphere chamber filled with a mixed solvent atmosphere, so that the surface of the inorganic nanofilm is exposed to the mixed solvent atmosphere of the first solvent and the second solvent, and solvent annealing treatment is performed in the mixed solvent atmosphere, and the first solvent atmosphere is used to enable the inorganic nanomaterial to have a certain ability to migrate and rearrange; the second solvent atmosphere is used to promote the stacking of the inorganic nanomaterial to be more dense, which reduces the contact area between the inorganic nanomaterial and the second solvent, thereby reducing the overall surface energy, improving the film formation uniformity and density of the thin film, and improving the surface roughness of the thin film, thereby achieving the effect of improving the luminous efficiency of the light-emitting device.
[0109] An embodiment of the present application further provides a display device, which includes the above-mentioned light-emitting device.
[0110] The display device can be any electronic product with a display function, including but not limited to smart phones, tablet computers, laptops, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, car displays, televisions or e-book readers, among which smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.
[0111] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.
[0112] Film Example 1
[0113] Step (1), providing an inorganic nanomaterial, wherein the inorganic nanomaterial is composed of a CdSe core, a CdS shell and an oleic acid ligand, and the average particle size of the nanoparticles is 13 nm;
[0114] Step (2), dispersing the inorganic nanomaterial in an n-octane solution, and spin coating the solution on an ITO substrate to form an inorganic nanofilm A;
[0115] Step (3), injecting a mixed solvent into the atmosphere chamber and letting it stand for 3 hours to form a solvent atmosphere of a mixed solvent in the atmosphere chamber, wherein the mixed solvent includes toluene as a first solvent and ethanol as a second solvent;
[0116] Step (4), placing the inorganic nanofilm A in an atmosphere chamber for solvent annealing for 30 minutes to obtain a first film B, wherein the temperature of the solvent annealing is 25° C.;
[0117] Step (5), taking out the film B and subjecting it to thermal annealing for 10 minutes to obtain a second film C, wherein the thermal annealing temperature is 100°C.
[0118] Film Example 2
[0119] The difference between this embodiment and embodiment 1 is that the mixed solvent includes n-hexane as the first solvent and isopropanol as the second solvent.
[0120] Film Example 3
[0121] The difference between this embodiment and embodiment 2 is that, in step (3), the solvent tank of the atmosphere chamber is heated to 35° C., and the mixed solvent is injected into the atmosphere chamber and left to stand for 3 hours to form a solvent atmosphere of the mixed solvent in the atmosphere chamber, wherein the solvent tank is used to store the mixed solvent, and the mixed solvent includes toluene as the first solvent and ethanol as the second solvent.
[0122] Film Example 4
[0123] The difference between this embodiment and embodiment 3 is that in step (1), the inorganic nanomaterial is replaced with CdSe quantum dots, wherein the average particle size of the nanoparticles of the CdSe quantum dots is 6 nm;
[0124] Film Comparative Example 1
[0125] The difference between this comparative example and Example 1 is that there is no step (3), and after completing step (2), step (4) is directly performed to perform thermal annealing on the inorganic nano film A to directly form the second film C.
[0126] Film Comparative Example 2
[0127] The difference between this comparative example and the composite film comparative example 1 is that the inorganic nanomaterial in step (1) is CdSe quantum dots, and the particle size of the nanoparticles is 6 nm.
[0128] Test result analysis:
[0129] The inorganic nanofilm A, the first film B and the second film C prepared by film examples 1 to 4, film comparative example 1 and film comparative example 2 were tested for surface roughness by atomic force microscopy (AFM), and the root mean square roughness value within the range of 20 μm×20 μm was removed. The test results are as follows:
[0130] As shown in Table 1.
[0131]
[0132] Table 1
[0133] According to the test results of film embodiments 1 to 3 and film comparison example 1, as well as film embodiment 4 and film comparison example 1, after the inorganic nanofilm A is formed, it is placed in an atmosphere chamber and solvent annealed in a mixed solvent atmosphere. The surface roughness of the first film B can be effectively reduced. After thermal annealing, the surface roughness of the second film C can be further reduced.
[0134] Light emitting device embodiment 1
[0135] Step (1), providing an ITO substrate, spin coating a PEDOT:PSS solution on the ITO substrate, and annealing the substrate at 150°C for 15 minutes to form a 40 nm thick hole injection layer;
[0136] Step (2), spin coating the TFB solution on the hole injection layer, and annealing the layer at 150° C. for 15 min to form a hole transport layer with a thickness of 30 nm;
[0137] Step (3), forming a 25 nm thick quantum dot light emitting layer on the hole transport layer using the preparation method of the above-mentioned thin film embodiment 1;
[0138] Step (4), evaporating ZnO nanocrystals on the quantum dot light-emitting layer to form a 30 nm thick electron transport layer;
[0139] Step (5): Ag is evaporated onto the electron transport layer to form an electron transport layer with a thickness of 30 nm.
[0140] Light emitting device embodiments 2 to 4
[0141] The only difference from the light emitting device embodiment 1 is that the quantum dot light emitting layer described in step (3) is replaced by the quantum dot light emitting layer prepared by the preparation method of thin film embodiments 2 to 4.
[0142] Light-emitting device comparative example 1
[0143] The difference between this comparative example and the light-emitting device embodiment 1 is that in the above step (3), a quantum dot light-emitting layer with a thickness of 25 nm is formed on the hole transport layer by adopting the preparation method of the above thin film comparative example 1.
[0144] Light-emitting device comparative example 2
[0145] The difference between this comparative example and the light-emitting device embodiment 1 is that in the above step (3), a quantum dot light-emitting layer with a thickness of 25 nm is formed on the hole transport layer by adopting the preparation method of the above thin film comparative example 2.
[0146] Test result analysis:
[0147] The light-emitting devices prepared in light-emitting device embodiments 1 to 4 and light-emitting device comparative examples 1 and 2 were tested for maximum external quantum efficiency (EQEmax, %) using an external quantum efficiency optical testing instrument. The test results are shown in Table 2.
[0148]
[0149] Table 2
[0150] According to the test results of light-emitting device embodiments 1 to 3 and light-emitting device comparison example 1, as well as light-emitting device embodiment 4 and light-emitting device comparison example 2, after the quantum dot light-emitting layer is prepared and placed in an atmosphere chamber, and solvent annealing is performed in a mixed solvent atmosphere, it is beneficial to improve the performance of the light-emitting device.
[0151] In summary, the quantum dot light-emitting layer treated in a mixed solvent atmosphere has good film uniformity and density, which improves the surface roughness of the inorganic nanofilm, thereby improving the luminous efficiency of the light-emitting device.
[0152] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is similarly within the scope of patent protection of this application.
Claims
1. A method for preparing a thin film, It is characterized in that The following steps are involved: Providing a mixed solution including an inorganic nanomaterial and a solvent; Treating the mixed solution to volatilize the solvent in the mixed solution to obtain an inorganic nanofilm including inorganic nanomaterials; Placing the inorganic nanofilm in an atmosphere chamber for solvent annealing to obtain the film; A solvent atmosphere of a mixed solvent is formed in the atmosphere chamber, wherein the mixed solvent includes a first solvent and a second solvent, the solubility of the first solvent in the inorganic nanomaterial is greater than 20 mg / ml, and the solubility of the second solvent in the inorganic nanomaterial is less than 3 mg / ml.
2. The method for preparing the thin film according to claim 1, It is characterized in that The step of treating the mixed solution comprises placing the mixed solution in a static state at a temperature of 25° C. to 30° C.; And / or, the time for the static treatment is 1 min to 10 min; And / or, the temperature during the solvent annealing treatment is 10°C to 50°C; And / or, the solvent annealing treatment is performed for 10 minutes to 3 hours.
3. The method for preparing the thin film according to claim 1, It is characterized in that The boiling point of the first solvent is less than or equal to 150° C., and the boiling point of the second solvent is less than or equal to 150° C.; and / or, the absolute value of the difference between the boiling point of the first solvent and the boiling point of the second solvent is less than or equal to 40° C.; And / or, the volume ratio of the first solvent to the second solvent is in the range of (1:10) to (10:1).
4. The method for preparing a thin film according to any one of claims 1 to 3, It is characterized in that The inorganic nanomaterial includes a quantum dot material, and the quantum dot material includes one or more of a single structure quantum dot and a core-shell structure quantum dot. The material of the single structure quantum dot, the core material and the shell material of the core-shell structure quantum dot are independently selected from at least one of a II-VI group compound, a IV-VI group compound, a III-V group compound and a I-III-VI group compound. The shell layer of the core-shell structure quantum dot includes one or more layers, wherein the II-VI group compound includes CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZ At least one of nS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, group IV-VI The compound includes at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, and the III-V compound includes GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, G At least one of aPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound is, but is not limited to, CuInS 2 、CuInSe 2 AgInS 2 At least one of .
5. The method for preparing the thin film according to claim 4, It is characterized in that At least part of the inorganic nanomaterials further comprises a hydrophobic ligand connected to the surface thereof, wherein the hydrophobic ligand comprises at least one of substituted or unsubstituted C6-C24 fatty acids, substituted or unsubstituted C6-C24 fatty amines, substituted or unsubstituted C6-C24 aliphatic thiols, substituted or unsubstituted C6-C24 aliphatic sulfides, substituted or unsubstituted C6-C24 aliphatic phosphines, substituted or unsubstituted C6-C24 aliphatic phosphine oxides, substituted or unsubstituted C8-C20 aliphatic phosphoric acids, substituted or unsubstituted C6-C24 aliphatic phosphates, substituted or unsubstituted C6-C24 aliphatic phosphorous acids, and substituted or unsubstituted C6-C24 aliphatic phosphites, wherein the substituted substituent is selected from at least one of C1-C6 alkyl, C1-C6 alkoxy, and halogen; Optionally, the fatty acid includes at least one of capric acid, undecylenic acid, tetradecanoic acid, oleic acid, linoleic acid, and stearic acid; Optionally, the aliphatic mercaptan includes at least one of octyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan; Optionally, the fatty amine includes at least one of oleylamine, octadecylamine, octylamine, dioctylamine and trioctylamine; Optionally, the (oxygen) phosphine ligand includes at least one of trioctylphosphine and trioctylphosphine oxide; And / or, the average particle size of the quantum dot material is 6nm to 13nm; and / or, the solvent comprises at least one of n-octane, benzene, toluene, cyclohexane, hexane, and cyclooctane; and / or, the first solvent comprises at least one of chloroform, benzene, toluene, xylene, hexane, heptane, and octane; And / or, the second solvent includes at least one of methanol, ethanol, propanol, butanol, ethyl acetate and acetone.
6. The method for preparing a thin film according to any one of claims 1 to 3, It is characterized in that Before the step of placing the inorganic nanofilm in an atmosphere chamber for solvent annealing, the following steps are also included: The mixed solvent is injected into the atmosphere chamber and allowed to stand, and the temperature in the atmosphere chamber is adjusted to a set temperature.
7. The method for preparing the thin film according to claim 6, It is characterized in that The mixed solvent is left in the atmosphere chamber for 2 to 3 hours; And / or, the set temperature ranges from 25°C to 50°C.
8. A film, It is characterized in that The film is prepared by the film preparation method according to any one of claims 1 to 7.
9. A light emitting device, It is characterized in that include: An anode layer and a cathode layer are arranged opposite to each other; The light-emitting layer is prepared by the thin film preparation method according to any one of claims 1 to 7, and the light-emitting layer is arranged between the anode layer and the cathode layer.
10. A display device, It is characterized in that The display device comprises the light emitting device according to claim 9.