Thin film, preparation method thereof and light-emitting device

Abstract

The invention belongs to the technical field of display, and relates to a thin film, a preparation method thereof and a light-emitting device. The thin film comprises a first sub-layer thin film and a second sub-layer thin film which are sequentially arranged in a laminated mode, the first sub-layer thin film is made of first inorganic nano-particles and first ligands, and the second sub-layer thin film is made of second inorganic nano-particles, second ligands and third ligands. The thin film provided by the invention can effectively improve the surface defects of the inorganic nanoparticles and improve the performance of the device.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and more specifically, to a thin film, a preparation method thereof, and a light-emitting device. Background Art

[0002] Inorganic nanomaterials are widely used as electron transport materials. The thin films prepared therefrom have relatively appropriate energy band positions, greatly improving the electron injection efficiency. Moreover, their deep valence band positions can effectively prevent hole leakage, effectively improving the charge balance in the light-emitting layer and further enhancing the performance of the light-emitting device. However, during the synthesis of inorganic nanomaterials, due to the presence of a large number of dangling bonds and surface groups on the surface, inorganic nanomaterials have a high density of surface defects. Existing technologies generally insert organic or inorganic materials at the interface to hinder electron injection and repair interface defects to appropriately reduce the hole leakage channels. However, this solution has high requirements for the modification materials at the interface and poor adaptability. Therefore, a simpler, more economical, and effective method is needed to solve the influence of the above defects on the device performance. Summary of the Invention

[0003] To solve the above technical problems, an embodiment of the present application provides a thin film, and the thin film adopts the following technical solution:

[0004] A thin film, which includes a first sub-layer thin film and a second sub-layer thin film stacked in sequence. The material of the first sub-layer thin film includes first inorganic nanoparticles and a first ligand, and the material of the second sub-layer thin film includes second inorganic nanoparticles, a second ligand, and a third ligand;

[0005] Wherein, the first ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, thiocyanato group; the third ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, thiocyanato group;

[0006] The second ligand includes at least one of halogen ions, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, C4-C24 aliphatic thiols.

[0007] Furthermore,

[0008] The content of the first ligand in the first sub-layer thin film is greater than the content of the third ligand in the second sub-layer thin film;

[0009] And / or, the first inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS; and / or

[0010] The second inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

[0011] Furthermore, the thickness of the first sub-layer film is 10 nm to 30 nm; and / or

[0012] The thickness of the second sub-layer film is 10 nm to 30 nm; and / or

[0013] The hydroxyl content in the first ligand of the first sub-layer film is 0.6 to 0.8; and / or

[0014] The hydroxyl content in the third ligand of the second sub-layer film is 0.2 to 0.5; and / or

[0015] In the second sub-layer thin film, the mass ratio of the third ligand to the second ligand is (9-16):6;

[0016] The content of the first ligand in the first sub-layer thin film is 0.6-0.8; and / or

[0017] The content of the third ligand in the second sub-layer thin film is 0.2-0.5.

[0018] Correspondingly, the present application also provides a method for preparing a thin film, the preparation method comprising:

[0019] Providing a first solution containing inorganic nanoparticles and an atmosphere solution;

[0020] Setting the first solution as a preformed film;

[0021] Using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the thin film;

[0022] Wherein, the atmosphere solution includes at least one of soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiols.

[0023] Further, the step of setting the first solution as a preformed film includes:

[0024] Depositing the first solution to form a preformed film;

[0025] The step of using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the thin film includes:

[0026] Soaking the preformed film in the atmosphere solution to form an atmosphere liquid film covering the surface of the preformed film;

[0027] Treating the soaked preformed film to remove the atmosphere liquid film to obtain the thin film;

[0028] Optionally, the thickness of the atmosphere liquid film is 10nm-15nm.

[0029] Further, the preformed film is a liquid film;

[0030] The step of using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the thin film includes:

[0031] Making the atmosphere solution form an atmosphere gas;

[0032] Making the atmosphere gas contact with the preformed film and treating the preformed film to form the thin film;

[0033] Optionally, the partial pressure of the atmosphere gas is 5 Pa to 15 Pa.

[0034] Furthermore, the treatment is annealing treatment, wherein the annealing temperature is 50 °C to 150 °C; and / or,

[0035] The annealing time is 5 min to 20 min.

[0036] Furthermore, the material of the atmosphere solution includes an atmosphere solute and an atmosphere solvent. The atmosphere solute includes at least one of soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiol compounds. The atmosphere solvent includes alcohol solvents and alcohol ether solvents.

[0037] Furthermore, when the atmosphere solute includes soluble metal halides, the atmosphere solute includes at least one of NaF and NaI;

[0038] When the atmosphere solute includes compounds containing halogenated hydrocarbons, the atmosphere solute includes at least one of fluoromethane, sodium chloride, and iodoform; and / or

[0039] When the atmosphere solute contains fatty alcohols, the atmosphere solute includes at least one of 2,2-difluoroethanol, allyl alcohol, and methallyl alcohol; and / or

[0040] When the atmosphere solute includes compounds containing fatty ethers, the atmosphere solute includes diethyl ether; and / or

[0041] When the atmosphere solute includes compounds containing fatty acids, the atmosphere solute includes at least one of 2,4-dichlorophenylacetic acid, acetic acid, and acetone; and / or,

[0042] When the atmosphere solute includes compounds containing fatty amines, the atmosphere solute includes at least one of oleylamine, tetradecylamine, and ethylpropylamine; and / or,

[0043] When the atmosphere solute includes compounds containing aliphatic thiols, the atmosphere solute includes at least one of isobutyl mercaptan, 2,4-dichlorophenylacetic acid, and methanethiol; and / or

[0044] When the atmosphere solvent includes alcohol solvents, the atmosphere solute includes at least one of methanol, ethanol, propanol, butanol, and ethylene glycol; and / or

[0045] When the atmosphere solvent includes alcohol ether solvents, the atmosphere solute includes propylene glycol dimethyl ether and ethylene glycol monomethyl ether; and / or

[0046] The concentration of the atmosphere solute is 5 mg / mL to 10 mg / mL.

[0047] Correspondingly, the present application further provides a light-emitting device, which includes a functional layer prepared by the preparation method of the thin film as described above; or

[0048] The functional layer is the thin film as described in any one of the above.

[0049] Further, the light-emitting device includes a first electrode, a hole functional layer, a light-emitting layer, an electron functional layer, and a second electrode stacked in sequence;

[0050] The electron functional layer includes a first electron functional layer and a second electron functional layer stacked in sequence, and the first electron functional layer is located between the light-emitting layer and the second electron functional layer;

[0051] The material of the first electron functional layer includes first inorganic nanoparticles and a first ligand, and the material of the second electron functional layer includes second inorganic nanoparticles, a second ligand, and a third ligand;

[0052] Among them, the first ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group; the third ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group;

[0053] The second ligand includes at least one of halide ions, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiols, and the content of the first ligand in the first electron functional layer is greater than the content of the third ligand in the second electron functional layer.

[0054] Further, the thickness of the first electron functional layer is 10 nm to 30 nm; and / or

[0055] The thickness of the second electron functional layer is 10 nm to 30 nm; and / or

[0056] The content of hydroxyl group in the first ligand of the first electron functional layer is 0.6 to 0.8; and / or

[0057] The content of hydroxyl group in the third ligand of the second electron functional layer is 0.2 to 0.5; and / or

[0058] In the second electron functional layer, the mass ratio of the third ligand to the second ligand is (9 to 16):6;

[0059] The content of the first ligand in the first electron functional layer is 0.6 to 0.8; and / or

[0060] The content of the third ligand in the second electronic functional layer is 0.2 to 0.5; and / or

[0061] The first inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS; and / or

[0062] The second inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

[0063] Compared with the prior art, the embodiments of the present application mainly have the following beneficial effects:

[0064] The thin film provided by the present application can effectively improve the surface defects of inorganic nanoparticles and improve the device performance. Description of the Drawings

[0065] To more clearly illustrate the solutions in the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0066] Figure 1 It is a flowchart of the preparation method of the thin film of the application embodiment;

[0067] Figure 2 It is a structural diagram of the light-emitting device of the embodiment of the present application.

[0068] Reference numerals:

[0069] First electrode 100, hole functional layer 200, light-emitting layer 300, electron functional layer 400, first electron functional layer 410, second electron functional layer 420, second electrode 500. Detailed implementation manners

[0070] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying 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 in 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 implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0071] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; and "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "including" means "including but not limited to". The terms first, second, third, etc. are only used as labels, and no numerical requirements are imposed or an order is established.

[0072] In the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0073] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one item (or one) below", or similar expressions thereof refer to any combination of these items, including any combination of single item (or one) or plural items (or ones). For example, "at least one item (or one) among a, b, or c", or "at least one item (or one) among 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.

[0074] Various embodiments of this application may 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 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 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.

[0075] Please refer to Figure 2 This application provides a thin film, which includes a first sub - layer thin film and a second sub - layer thin film stacked in sequence. The material of the first sub - layer thin film includes first inorganic nanoparticles and a first ligand, and the material of the second sub - layer thin film includes second inorganic nanoparticles, a second ligand, and a third ligand;

[0076] Among them, the first ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group; the third ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group;

[0077] The second ligand includes at least one of halogen ions, C1 - C24 halogenated hydrocarbons, C2 - C24 fatty alcohols, C4 - C24 fatty ethers, C8 - C24 fatty acids, C8 - C24 fatty amines, and C4 - C24 aliphatic thiols.

[0078] Because the thin film of this application has a first sub - layer thin film and a second sub - layer thin film, and the second ligand in the second sub - layer thin film can combine with the third ligand to reduce the amount of the third ligand, this application can change the surface defects on both sides of the thin film by adjusting the content of the second ligand, thereby enabling the first sub - layer thin film and the second sub - layer thin film to exhibit different properties. Refer to Figure 2, taking the thin film as the electronic functional layer 400 as an example. At this time, the first sub-layer thin film is the second electronic functional layer 420, and the second sub-layer thin film is the first electronic functional layer 410. The first electronic functional layer 410 is in contact with the light-emitting layer 300, and the second electronic functional layer 420 is in contact with the second electrode 500; the second ligand can coordinate with the third ligand, thereby reducing the content of the third ligand inside the thin film. For example, in this example, the second ligand can be oleylamine, and the first ligand and the third ligand are hydroxyl groups. At this time, the hydroxyl groups in the first electronic functional layer 410 will combine with oleylamine, thereby reducing the content of hydroxyl groups in the first electronic functional layer 410.

[0079] When the light-emitting device continuously operates to the stable state, due to the existence of the first electron transport layer 410 with a low surface hydroxyl group amount, the negatively charged state of the light-emitting layer 300 will still occur and it is easy to reach dynamic equilibrium. As a result, the final electron injection efficiency is at a relatively low level in order to form a carrier injection balance with the hole injection efficiency. Therefore, the low hydroxyl group amount makes it easy for the light-emitting layer 300 to reach the carrier injection balance state when continuously operating to the stable state, and thus a good light-emitting device lifetime is obtained. On the other hand, the second electronic functional layer 410 with a high hydroxyl group amount is in contact with the second electrode 500 (cathode), which can reduce the electrons injected into the quantum dot light-emitting layer, making the electron injection efficiency of the light-emitting layer 300 relatively low in the initial stage of operation, achieving the injection balance of carriers in the light-emitting device, and the device being in a state of the same carrier balance, so that the light-emitting region has a relatively high external quantum efficiency.

[0080] In summary, the thin film of this embodiment can effectively improve the surface defects of inorganic nanoparticles and improve the device performance.

[0081] Furthermore, the content of the first ligand in the first sub-layer thin film is greater than the content of the third ligand in the second sub-layer thin film;

[0082] And / or, the first inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS; and / or

[0083] The second inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

[0084] Furthermore, the thickness of the first sub-layer film is 10 nm to 30 nm; and / or the thickness of the second sub-layer film is 10 nm to 30 nm. Within this thickness range, the first sub-layer film and the second sub-layer film can avoid the influence of the other sub-layer film on its corresponding film layer. For example, when the film is an electronic functional layer, the first sub-layer film is the second electronic functional layer 420, and the second sub-layer film is the first electronic functional layer 410, then the thickness of the first electronic functional layer 410 can avoid the direct transmission of electron leakage from the second electronic functional layer 420 to the light-emitting layer 300. At the same time, it can also avoid the electronic breakdown of the electronic functional layer 400.

[0085] It can be understood that the thickness of either the first sub-layer film or the second sub-layer film can be any value among 1 nm, 2 nm, 3 nm, 4 nm, 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, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm or a range formed by any two of these values.

[0086] Furthermore, the hydroxyl content in the first ligand of the first sub-layer film is 0.6 - 0.8; and / or the hydroxyl content in the third ligand of the second sub-layer film is 0.2 - 0.5. When the hydroxyl content in the first ligand of the first sub-layer film is 0.6 - 0.8 and the hydroxyl content in the third ligand of the second sub-layer film is 0.2 - 0.5, the hydroxyl content of the first sub-layer film enables a better carrier balance state and higher external quantum efficiency of the light-emitting device. At the same time, the second sub-layer film can endow the light-emitting device with a better device lifetime, so that the finally obtained light-emitting device has both a high external quantum efficiency and a device lifetime.

[0087] It can be understood that the hydroxyl content in the first ligand of the first sub-layer film can be any value among 0.6, 0.65, 0.7, 0.75, 0.8 or a range formed by any two of these values. The hydroxyl content in the third ligand of the second sub-layer film can be any value among 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a range formed by any two of these values.

[0088] Furthermore, in the second sub-layer film, the mass ratio of the third ligand to the second ligand is (9 - 16):6; the content of the first ligand in the first sub-layer film is 0.6 - 0.8; and / or

[0089] the content of the third ligand in the second sub-layer film is 0.2 - 0.5.

[0090] As shown in the above embodiments, when the content of the first ligand in the first sub-layer film is 0.6 - 0.8 and the content of the third ligand in the second sub-layer film is 0.2 - 0.5, different properties are presented on both sides of the film, enabling the film to match the requirements of the light-emitting device. Therefore, this film can make the carrier balance state of the light-emitting device better and the external quantum efficiency higher. At the same time, the second sub-layer film can endow the light-emitting device with a better device lifetime, so that the finally obtained light-emitting device has both a high external quantum efficiency and a device lifetime.

[0091] It is understandable that the function of the third ligand is to replace the second ligand and reduce the content of the second ligand in the second sub-layer thin film. Therefore, the mass ratio of the third ligand to the second ligand is (9-16):6. The mass ratio of the third ligand to the second ligand can be any value in 9:6, 10:6, 11:6, 12:6, 13:6, 14:6, 15:6, 16:6 or the range formed by any two values. The content of the first ligand in the first sub-layer thin film can be any value in 0.6, 0.65, 0.7, 0.75, 0.8 or the range formed by any two values. The content of the third ligand in the second sub-layer thin film can be any value in 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or the range formed by any two values

[0092] Correspondingly, the present application also provides a method for preparing a thin film. The method for preparing the thin film includes:

[0093] S100, providing a first solution containing inorganic nanoparticles and an atmosphere solution;

[0094] S200, setting the first solution as a prefabricated film;

[0095] S300, forming a preset atmosphere with the atmosphere solution and treating the prefabricated film to obtain a thin film.

[0096] Wherein, the atmosphere solution includes at least one of compounds such as soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiols.

[0097] To realize the regulation of the number of various groups (such as cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphorus group, amino group, carboxyl group, thiocyanato group, etc.) on the surface of the thin film, in the prior art, when preparing a functional layer solution capable of forming a thin film, a doping material is added to the functional layer solution, so that the doping material reacts with the functional layer material in the functional layer solution, thereby realizing the regulation of the number of groups on the surface of the thin film.

[0098] However, when a light-emitting device containing a multi-layer thin film structure needs to be prepared and the required number of groups for each thin film in the light-emitting device is different, the method of the prior art needs to re-prepare functional layer solutions containing different concentrations of doping materials, and the preparation time of the functional layer solution is usually long, which leads to low production efficiency of the thin film. At the same time, because the functional layer solution and the doping material have been mixed, in the process of preparing the thin film in the prior art, the groups and surface defects of the finally formed thin film cannot be adjusted in real time. Once it is found that the thin film does not meet the expectations after it is formed, the functional layer solution needs to be re-prepared and the thin film needs to be re-produced, which leads to a reduction in the production efficiency of the thin film.

[0099] It is understandable that when the atmosphere solution includes at least one of compounds containing soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiols, at this time, groups in the above compounds, such as amine groups, can exchange with hydroxyl groups in the functional layer material, thereby reducing the hydroxyl content on the film surface.

[0100] The preset atmosphere of this application includes a gas atmosphere and a liquid atmosphere. Both preset atmospheres can control the hydroxyl content on the film surface, and the prefabricated film is located in the preset atmosphere. Therefore, during the process of forming the film from the functional layer solution, it will be affected by the preset atmosphere. During the process of preparing the film, since the atmosphere solution usually includes an atmosphere solvent and an atmosphere solute, the reaction amount between the atmosphere solute and the functional layer material can be adjusted at any time by increasing the atmosphere solute in the atmosphere solution, drying the atmosphere solution, etc., for example, by adjusting the concentration of the atmosphere solute or the pressure of the gas atmosphere, so as to adjust the hydroxyl content on the film surface and improve the production efficiency of the light-emitting device.

[0101] Two methods for the preset atmosphere being a gas atmosphere and a liquid atmosphere are listed below.

[0102] Further, please refer to Figure 1 , the step S200 of setting the first solution as the prefabricated film includes:

[0103] Deposit the first solution to form a prefabricated film;

[0104] The steps included in step S300 of using the atmosphere solution to form a preset atmosphere and treating the prefabricated film to obtain a film include:

[0105] Immerse the prefabricated film in the atmosphere solution to form an atmosphere liquid film covering the surface of the prefabricated film;

[0106] Treat the immersed prefabricated film to remove the atmosphere liquid film to obtain a film;

[0107] Optionally, the thickness of the atmosphere liquid film is 10nm - 15nm.

[0108] At this time, the prefabricated film is a dry film. To avoid the atmosphere solution dispersing the functional layer solution and affecting the surface uniformity and performance of the final film, the functional layer solution can be dried first to form a functional layer prefabricated film, and then the atmosphere solution is covered on the functional layer prefabricated film by injection, spin coating, spraying, doctor blading, etc., and they are processed together to form a film. At this time, the atmosphere solution will directly contact the surface of the functional layer prefabricated film, and the functional layer solute can quickly react with the functional layer material, thereby improving the adjustment efficiency of the film groups and defects.

[0109] Furthermore, the thickness of the atmosphere liquid film is 10nm to 15nm. When the thickness of the atmosphere liquid film is between 10nm and 15nm, it can avoid the extension of the processing time due to the excessive thickness of the atmosphere liquid film, and can also avoid the atmosphere liquid film remaining on the surface of the film to affect the surface uniformity of the film. It can also avoid the liquid film being too thin to ensure the uniformity of the liquid film, resulting in uneven hydroxyl content in various parts of the film. In summary, the embodiments of the present application can improve the production efficiency of the film and improve the uniformity of the film surface. It can be understood that the thickness of the atmosphere liquid film includes 10nm, 11nm, 12nm, 13nm, 14nm, and 15nm.

[0110] For further information, please refer to Figure 1 The prefabricated film is a liquid film, and the atmosphere solution is used to form a preset atmosphere. The prefabricated film is processed to form a thin film. Step S200 includes:

[0111] The atmospheric solution is made to form an atmospheric gas;

[0112] contacting the atmosphere gas with the prefabricated film to treat the prefabricated film to form a thin film;

[0113] Optionally, the partial pressure of the atmosphere gas is 5Pa to 15Pa.

[0114] At this time, the prefabricated film is a liquid film formed by the flow of the functional layer solution. If the preset atmosphere is a liquid, the preset atmosphere may penetrate into the prefabricated film when it is in contact with the prefabricated film (dry film), resulting in low surface uniformity of the film finally formed. The preset atmosphere of this embodiment covers the prefabricated film (liquid film) in the form of gas, so it is possible to avoid the preset atmosphere from destroying the functional layer solution and thus affecting the surface uniformity of the film. Specifically, the substrate can be transferred to a device with a containing cavity (such as a glove box), and then the atmosphere gas can be injected around the prefabricated film so that the containing cavity is filled with the atmosphere gas, and the atmosphere gas will contact the prefabricated film. It can be understood that as long as the functional layer solution is in contact with the atmosphere gas, the control of the groups and surface defects of the film finally formed can be achieved, such as continuous ventilation of the functional layer solution. It can be understood that in order to avoid the influence of water and oxygen, the atmosphere gas can be formed in an environment of nitrogen or inert gas.

[0115] Further, the partial pressure of the atmosphere gas is 5 Pa to 15 Pa. The partial pressure is the pressure that a gas would have if all other gases were removed from a mixed gas system while keeping the system volume and temperature constant. That is, at a given temperature and volume, it is the pressure when only this gas exists alone and fills the container. Therefore, the greater the partial pressure, the greater the proportion of the atmosphere solution gas in the accommodation cavity can be understood, that is, the compounds including halogenated hydrocarbons, fatty alcohols, fatty ethers, fatty acids, fatty amines, and fatty thiols in contact with the prefabricated film. When the proportion of the atmosphere gas is 5 Pa to 15 Pa, it can ensure that the functional layer solution fully reacts with the atmosphere gas and avoid damage to the functional layer solution by the atmosphere gas under high pressure.

[0116] Further, the treatment in step S300 is an annealing treatment, which includes:

[0117] Annealing the functional layer liquid film; and / or,

[0118] The annealing temperature is 50°C to 150°C; and / or,

[0119] The annealing time is 5 min to 20 min. The selection of the annealing temperature can affect the crystallinity and crystal size of the thin film. The annealing temperature in this application can improve the orderliness and size of the functional layer material in the thin film, thereby improving the optical properties of the thin film. The annealing time affects the growth rate and degree of crystal growth. The annealing time in this application allows the crystals to have more time to grow and arrange, thereby improving the surface topography uniformity of the thin film and avoiding too long preparation time, that is, improving the production efficiency. It can be understood that the annealing temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C. The annealing time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min.

[0120] Further, the material of the atmosphere solution includes an atmosphere solute and an atmosphere solvent. The atmosphere solute includes at least one of soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiol compounds. The atmosphere solvent includes alcohol solvents and alcohol ether solvents. Within this carbon atom number range, the above compounds have a higher efficiency of exchanging with hydroxyl groups.

[0121] In summary, the present application can adjust the hydroxyl content on the surface of the electron transport layer by reacting the atmosphere solution with the functional layer solution, thereby achieving the regulation of the electron rate, reaching the carrier injection balance under the stable working state, and further effectively improving the service life of the light-emitting device.

[0122] Please refer to Figure 2 , in a possible implementation manner, the electron transport layer includes a first electron transport layer and a second electron transport layer. The amount of hydroxyl groups on the surface of the first electron transport layer is less than that of the second electron transport layer, and the two are stacked along the direction perpendicular to the light-emitting layer 300 or the cathode. The amount of hydroxyl groups is the ratio of the peak area of hydroxyl oxygen to the peak area of lattice oxygen. In this case, when using a double-layer zinc oxide electron transport, among them, the zinc oxide thin film with a high surface hydroxyl group content can reduce the electrons injected into the light-emitting layer 300, making the electron injection efficiency of the light-emitting device relatively low in the initial stage of operation, achieving the injection balance of carriers in the light-emitting device, and the device being in a state of the same carrier balance, thus having a high external quantum efficiency; when the light-emitting device continues to operate to a stable state, due to the existence of the zinc oxide thin film with a low surface hydroxyl group content, the negatively charged state of the light-emitting layer 300 will still occur and it is easy to reach a dynamic balance, and then the final electron injection efficiency is at a relatively low level, so as to form a carrier injection balance with the hole injection efficiency. Therefore, the service life of the obtained light-emitting device will also be improved.

[0123] Furthermore, when the atmosphere solute includes a compound containing a soluble metal halide, the atmosphere solute includes NaF, NaI; and / or, when the atmosphere solute contains a fatty alcohol, the atmosphere solute includes 2,2-difluoroethanol, allyl alcohol, methacrylic alcohol; and / or, when the atmosphere solute includes a compound containing a fatty ether, the atmosphere solute includes diethyl ether; and / or, when the atmosphere solute includes a compound containing a fatty acid, the atmosphere solute includes 2,4-dichlorophenylacetic acid, acetic acid, acetone; and / or, when the atmosphere solute includes a compound containing a fatty amine, the atmosphere solute includes oleylamine, tetradecylamine, ethylpropylamine; and / or, when the atmosphere solute includes a compound containing a fatty thiol, the atmosphere solute includes isobutyl mercaptan, 2,4-dichlorophenylacetic acid, methyl mercaptan; and / or, when the atmosphere solvent includes an alcohol solvent, the atmosphere solvent includes methanol, ethanol, propanol, butanol, ethylene glycol; and / or, when the atmosphere solvent includes an alcohol ether solvent, the atmosphere solvent includes propylene glycol dimethyl ether, ethylene glycol monomethyl ether; and / or,

[0124] Furthermore, the preparation steps of the atmosphere solution include:

[0125] Mix and stir the atmosphere solute and the atmosphere solvent to obtain the atmosphere solution, where the stirring temperature is 15°C to 25°C; and / or,

[0126] The stirring time is 20 h to 30 h. When the atmosphere solution forms a clear solution without flocculent precipitate during stirring, the preparation of the atmosphere solution is completed. Within the stirring temperature range of 15°C to 25°C, the reaction rate can be controlled to avoid unnecessary side reactions or uncontrolled reactions, ensure that the prepared atmosphere solution has the required composition and properties, and maintain the uniformity of the reaction solution to prevent the reactants from precipitating or separating. Within the stirring time of 20 h to 30 h, the reaction can proceed sufficiently to ensure that all components in the mixture react fully and reach the required stability and uniformity. Preferably, the stirring temperature is 25°C and the stirring time is 24 h.

[0127] It can be understood that the stirring temperature can be 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C. The stirring time can be 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h, 30 h.

[0128] Furthermore, the functional layer solution includes a functional layer solvent and at least one of a hole functional layer material, a light-emitting layer material, and an electron functional layer material;

[0129] The hole functional layer material includes 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;

[0130] The luminescent layer 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. The group II-VI semiconductor compounds are selected from 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; the group III-V semiconductor compounds are selected from 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; the group IV-VI semiconductor compounds are selected from at least one of SnSe, SnTe, PbSe, PbS, PbTe, SnSeS, SnSeTe, SnSTe, SnPbS, SnPbSe, SnPbTe, PbSTe, PbSeS, PbSeTe, SnPbSSe, SnPbSeTe, SnPbSTe; and / or,

[0131] The electron functional layer material includes 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 tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate, and the doped 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.

[0132] Correspondingly, please refer to Figure 2 Correspondingly, the present application also provides a light-emitting device, which includes an anode and a cathode arranged oppositely, a luminescent layer arranged between the anode and the cathode, and an electron functional layer arranged between the luminescent layer and the cathode. Specifically, the light-emitting device includes a first electrode 100 (anode), a hole functional layer 200, a luminescent layer 300, an electron functional layer 400, and a second electrode 500 (cathode) which are sequentially stacked. Among them, the functional layer is prepared by the preparation method of the thin film in any one of the above embodiments, or the functional layer is the thin film in the above embodiments.

[0133] Therefore, the functional layer of the light-emitting device in this embodiment can have different contents of the first ligand and the third ligand on both sides through the first sub-layer thin film and the second sub-layer thin film it has, thereby making the two sides of the thin film have different properties, and further improving the external quantum efficiency and service life of the light-emitting device.

[0134] Furthermore, the electron functional layer 400 includes a first electron functional layer 410 and a second electron functional layer 420 stacked in sequence. The first electron functional layer 410 is located between the light-emitting layer and the second electron functional layer 420. As described in the above embodiment, the first electron functional layer 410 and the second electron functional layer 420 of the present application have different properties, enabling the electron functional layer 400 to contact the light-emitting layer 300 with the side having a higher hydroxyl content and contact the second electrode 500 (cathode) with the side having a lower hydroxyl content, thereby improving both the service life and the external quantum efficiency of the light-emitting device.

[0135] The following specifically describes the thin film of the present application through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0136] Example A

[0137] This embodiment provides a thin film, and the thin film preparation method is as follows:

[0138] The zinc oxide ink is inkjet printed onto the substrate, transferred to the VCD chamber for drying, transferred to the glove box hot stage filled with pure nitrogen, and the oleylamine vapor is introduced to form a nitrogen inhibition atmosphere with an oleylamine partial pressure of 10 Pa. Subsequently, annealing treatment is performed on the 100 °C hot stage for 10 min to form the first sub-layer thin film; the zinc oxide ink is inkjet printed onto the first sub-layer thin film, transferred to the VCD chamber for drying, transferred to the glove box hot stage filled with pure nitrogen, and the oleylamine vapor is introduced to form an atmosphere with 5 pa oleylamine gas. Subsequently, annealing treatment is performed on the 100 °C hot stage for 10 min to form the second sub-layer thin film.

[0139] Example B

[0140] This embodiment is basically the same as Example A, except that: when fabricating the first sub-layer thin film, a nitrogen inhibition atmosphere with an oleylamine gas partial pressure of 5 Pa is formed.

[0141] Example C

[0142] This embodiment is basically the same as Example A, except that: when fabricating the first sub-layer thin film, a nitrogen inhibition atmosphere with an oleylamine gas partial pressure of 15 Pa is formed.

[0143] Example D

[0144] The zinc oxide ink is inkjet printed onto the light-emitting layer 300, and the zinc oxide solution is dried to form a dry film. Subsequently, an oleylamine solution with a concentration of 8 mg / mL is sprayed onto the dry zinc oxide film to form an ambient liquid film on the dry zinc oxide film, and the thickness of the ambient liquid film is 10 mm. It is introduced into a glove box hot stage with pure nitrogen, and annealed for 10 min using a 100 °C hot stage to form the first sub-layer film. The zinc oxide ink is inkjet printed onto the first sub-layer film, introduced into a VCD chamber for drying, and then annealed for 10 min using a 100 °C hot stage to form the second sub-layer film.

[0145] Example E

[0146] This example is basically the same as Example A, except that isobutanethiol vapor is introduced.

[0147] Comparative Example A

[0148] The zinc oxide ink is inkjet printed onto the light-emitting layer 300, introduced into a VCD chamber for drying, and then annealed for 10 min using a 100 °C hot stage to form the first sub-layer film. The zinc oxide ink is inkjet printed onto the first sub-layer film again, introduced into a VCD chamber for drying, and then annealed for 10 min using a 100 °C hot stage to form the second sub-layer film.

[0149] The films of Examples A-E and Comparative Example A are detected by X-ray photoelectron spectroscopy (XPS). Specifically, taking the zinc oxide film as an example, in the X-ray photoelectron spectroscopy (XPS) detection results, the O1s spectrum can be deconvoluted into three sub-peaks, namely the OM peak representing the molar concentration of oxygen atoms in the zinc oxide crystal (the peak position is between 529 eV and 531 eV), the OV peak representing the molar concentration of oxygen vacancies in the zinc oxide crystal (the peak position is at 531 eV - 532 eV), and the OH peak representing the molar concentration of hydroxyl ligands on the surface of the zinc oxide crystal (the peak position is at 532 eV - 534 eV). The area ratio between each sub-peak represents the molar concentration ratio of different types of oxygen atoms in the film. Therefore, the amount of surface hydroxyl groups of the film is defined as: the area of the OH peak / the area of the OM peak, that is, the amount of surface hydroxyl groups of the zinc oxide film is: the ratio of the molar concentration of hydroxyl ligands on the surface of the zinc oxide film to the molar concentration of oxygen atoms in the zinc oxide crystal. Its hydroxyl content is shown in Table 1 below.

[0150] Table 1

[0151]

[0152]

[0153] As can be seen from Table 1:

[0154] According to Example A, Example D and Comparative Example A, when the thin film has a first sub-layer thin film and a second sub-layer thin film, the hydroxyl content of the first sub-layer thin film and the second sub-layer thin film is changed by an oleylamine solution, so that the hydroxyl contents of the two thin films are different.

[0155] According to Example A, Example B, and Example C, it can be seen that by changing the partial pressure of oleylamine, the external quantum efficiency and service life of the finally formed thin film can be adjusted, that is, it is proved that changing the partial pressure of the atmosphere solution can adjust the hydroxyl content in the thin film.

[0156] According to Example A and Example E, it can be known that compounds such as oleylamine and isobutyl mercaptan can both adjust the hydroxyl content on the surface of the thin film.

[0157] In summary, the preparation method of the thin film of the present application can adjust the ligand content of the finally formed thin film by changing the concentration of the atmosphere solution and the partial pressure of the atmosphere gas formed by the atmosphere solution, so as to change the ligand content of the finally formed thin film.

[0158] The preparation method of the light-emitting device of the present application will be specifically described below through specific examples. The following examples are only partial examples of the present application and do not limit the present application.

[0159] Example 1

[0160] The present application provides a preparation method of a light-emitting device, and the preparation method is as follows:

[0161] Step 1, clean the ITO glass substrate, and further remove organic pollutants on the substrate surface and improve the wettability of the ITO surface with an ultraviolet ozone cleaner, and place the glass substrate on a hot stage at 230 °C for drying;

[0162] Step 2, prepare a hole transport layer, inkjet print TFB ink on the ITO substrate, after VCD drying, place it on a hot stage at 230 °C for 30 min of annealing treatment to form a hole transport layer;

[0163] Step 3, prepare a light-emitting layer, inkjet print CdSe quantum dot ink on the hole injection layer, after VCD drying, then use a hot stage at 100 °C for 10 min of annealing treatment to form a light-emitting layer.

[0164] Step 4, prepare an electron transport layer, inkjet print zinc oxide ink on the light-emitting layer 300, transfer it to a VCD chamber for drying, then transfer it to a glove box hot stage filled with pure nitrogen, introduce oleylamine vapor to form an atmosphere with an oleylamine gas partial pressure of 10 Pa, and then use a hot stage at 100 °C for 10 min of annealing treatment to form a first electron transport layer;

[0165] The zinc oxide ink is inkjet printed onto the first electron transport layer, then introduced into the VCD chamber for drying, and subsequently annealed on a hot stage at 100 °C for 10 min to form the second electron transport layer;

[0166] The solvent of the zinc oxide ink is ethanol;

[0167] Step 5: Prepare the electron injection layer. Evaporate 1 nm of LiF on the second electron transport layer by a vacuum evaporator to form the electron injection layer;

[0168] Step 6: Prepare the cathode. Evaporate approximately 100 nm of Al on the electron injection layer by a vacuum evaporator to form the cathode electrode.

[0169] Example 2

[0170] This example is basically the same as Example 1, except that: Step 4 is replaced with: The zinc oxide ink is inkjet printed onto the light-emitting layer 300, then introduced into the VCD chamber for drying, then introduced into the hot stage in a glove box filled with pure nitrogen, and oleylamine vapor is introduced to form an atmosphere with an oleylamine partial pressure of 10 Pa, and then annealed on a hot stage at 100 °C for 10 min to form the first electron transport layer; The zinc oxide ink is inkjet printed onto the first electron transport layer, then introduced into the VCD chamber for drying, then introduced into the hot stage in a glove box filled with pure nitrogen, and oleylamine vapor is introduced to form an atmosphere with an oleylamine gas of 5 Pa, and then annealed on a hot stage at 100 °C for 10 min to form the second electron transport layer.

[0171] Example 3

[0172] This example is basically the same as Example 2, except that: In Step 4, when fabricating the first electron transport layer, a nitrogen-inhibiting atmosphere with an oleylamine partial pressure of 5 Pa is formed.

[0173] Example 4

[0174] This example is basically the same as Example 2, except that: In Step 4, when fabricating the first electron transport layer, a nitrogen-inhibiting atmosphere with an oleylamine gas partial pressure of 15 Pa is formed.

[0175] Example 5

[0176] This example is basically the same as Example 1, except that: Step 4 is replaced with:

[0177] Prepare the electron transport layer. Inkjet print zinc oxide ink onto the light-emitting layer 300, and dry the zinc oxide solution to form a dry film. Subsequently, spray a layer of oleylamine solution with a concentration of 8 mg / mL onto the zinc oxide dry film to form an ambient liquid film on the zinc oxide dry film. The thickness of the ambient liquid film is 10 mm. Transfer it to a glove box hot stage with pure nitrogen introduced, and perform an annealing treatment at 100 °C for 10 min using the hot stage to form the first electron transport layer. Inkjet print the zinc oxide ink onto the first electron transport layer, transfer it to a VCD chamber for drying, and then perform an annealing treatment at 100 °C for 10 min using the hot stage to form the second electron transport layer.

[0178] Example 6

[0179] This example is basically the same as Example 2, except that in step 4, the thickness of the ambient liquid film is 20 mm.

[0180] Example 7

[0181] This example is basically the same as Example 2, except that in step 4, isobutyl mercaptan vapor is introduced.

[0182] Comparative Example 1

[0183] This example is basically the same as Example 1, except that step 4 is replaced with: Inkjet print zinc oxide ink onto the light-emitting layer 300, transfer it to a VCD chamber for drying, and then perform an annealing treatment at 100 °C for 10 min using the hot stage to form the first electron transport layer;

[0184] Inkjet print zinc oxide ink onto the first electron transport layer, transfer it to a VCD chamber for drying, and then perform an annealing treatment at 100 °C for 10 min using the hot stage to form the second electron transport layer.

[0185] Delete Comparative Example 2 first. If there is such a problem as you mentioned, it can be supplemented during the examination response. Anyway, the data of the comparative example can be provided at any time.

[0186] Use an IVL device to test the performance of the light-emitting devices of Examples 1 to 7 and Comparative Example 1. The time when the brightness decays to 95% under a constant current condition with an initial brightness of 1000 nit is used as the evaluation index for the lifetime of the light-emitting device. The external quantum efficiency at a brightness of 1000 cd / m2 is used as the external quantum efficiency index. The test results are shown in Table 2.

[0187] Table 2:

[0188] Type EQE (%) at 1000 cd / m2 L (cd / m2) at 4 V Example 1 20.3 8409 Example 2 20.55 8235 Example 3 19 7605 Example 4 17.5 7023 Example 5 19.5 7945 Example 6 18.2 7262 Example 7 19.5 7701 Comparative Example 1 15 6123

[0189] As can be seen from Table 2:

[0190] According to Embodiments 2 to 4 and Comparative Example 1, when the electron transport layer is a double-layer thin film, by using an oleylamine solution to change the hydroxyl content of the two layers of thin films, the hydroxyl content of the two layers of thin films can be made different, so that the hydroxyl content of the thin films respectively meets the required hydroxyl content of the cathode and the light-emitting layer 300, thereby improving the electron transport efficiency of the electron transport layer and the cathode and avoiding quenching of the light-emitting layer 300, so that the external quantum efficiency of the light-emitting device is improved and the service life is extended.

[0191] According to Embodiment 1, Embodiment 3, and Embodiment 4, by changing the partial pressure of oleylamine, the external quantum efficiency and service life of the finally formed light-emitting device can be adjusted.

[0192] According to Embodiment 2 and Embodiment 7, both the compound of oleylamine and isobutyl mercaptan can adjust the external quantum efficiency and service life of the light-emitting device.

[0193] According to Embodiment 5 and Embodiment 6, when the preset atmosphere is a liquid, the thickness of the atmosphere liquid film formed by its oleylamine solution will affect the external quantum efficiency and device life. When the thickness of the atmosphere liquid film is relatively large, the atmosphere liquid film may penetrate into the electron transport layer, thereby causing a decrease in the external quantum efficiency and life of the light-emitting device.

[0194] In summary, the method for preparing the thin film of the present application can adjust the concentration of the atmosphere solution and the partial pressure of the atmosphere gas formed by the atmosphere solution, so as to adjust the groups or surface defects of the thin film to reach the expected number, and then efficiently change the carrier transport efficiency and life of the light-emitting device.

[0195] The thin film, its preparation method, and the light-emitting device provided by the embodiments of the present application have been introduced in detail above. 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, according to 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.

[0196] Although the embodiments of the present 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 principle and spirit of the present application. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A film, characterized in that, The thin film includes a first sub-layer thin film and a second sub-layer thin film which are stacked in sequence. The material of the first sub-layer thin film includes first inorganic nanoparticles and a first ligand, and the material of the second sub-layer thin film includes second inorganic nanoparticles, a second ligand and a third ligand; Wherein, the first ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, thiocyanato group; the third ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, thiocyanato group; The second ligand includes at least one of halogen ions, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, C4-C24 aliphatic thiols.

2. The thin film according to claim 1, wherein the content of the first ligand in the first sub-layer thin film is greater than the content of the third ligand in the second sub-layer thin film; and / or, the first inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP, GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS, CuGaS; and / or The second inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

3. The thin film according to claim 1, characterized in that, The thickness of the first sub-layer film is 10 nm to 30 nm; and / or The thickness of the second sub-layer film is 10 nm to 30 nm; and / or The hydroxyl content in the first ligand of the first sub-layer film is 0.6 to 0.8; and / or The hydroxyl content in the third ligand of the second sub-layer film is 0.2 to 0.5; and / or In the second sub-layer film, the mass ratio of the third ligand to the second ligand is (9 to 16):6; The content of the first ligand of the first sub-layer film is 0.6 to 0.8; and / or The content of the third ligand of the second sub-layer film is 0.2 to 0.

5.

4. A method for preparing a thin film, characterized in that, The preparation method includes: Providing a first solution containing inorganic nanoparticles and an atmosphere solution; Setting the first solution as a preformed film; Using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the film; Wherein, the atmosphere solution includes at least one of soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiols.

5. The method for preparing the thin film according to claim 4, characterized in that, The step of setting the first solution as a preformed film includes: Depositing the first solution to form a preformed film; The step of using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the film includes: Soaking the preformed film in the atmosphere solution to form an atmosphere liquid film covering the surface of the preformed film; Treating the soaked preformed film to remove the atmosphere liquid film to obtain the film; Optionally, the thickness of the atmosphere liquid film is 10 nm to 15 nm.

6. The method for preparing a thin film according to claim 4, wherein The preformed film is a liquid film; The step of using the atmosphere solution to form a preset atmosphere and treating the preformed film to obtain the film includes: Making the atmosphere solution form an atmosphere gas; Making the atmosphere gas contact the preformed film and treating the preformed film to form the film; Optionally, the partial pressure of the atmosphere gas is 5 Pa to 15 Pa.

7. The method for preparing the thin film according to any one of claims 5 to 6, characterized in that, The treatment is an annealing treatment, wherein the annealing temperature is 50°C to 150°C; and / or, The annealing time is 5 min to 20 min.

8. The method for preparing the thin film according to claim 4, wherein The material of the atmosphere solution includes an atmosphere solute and an atmosphere solvent. The atmosphere solute includes at least one of soluble metal halides, C1-C24 halogenated hydrocarbons, C2-C24 fatty alcohols, C4-C24 fatty ethers, C8-C24 fatty acids, C8-C24 fatty amines, and C4-C24 aliphatic thiol compounds. The atmosphere solvent includes alcohol solvents and alcohol ether solvents.

9. The method for preparing the thin film according to claim 8, characterized in that, When the atmosphere solute includes soluble metal halides, the atmosphere solute includes at least one of NaF and NaI; When the atmosphere solute includes compounds containing halogenated hydrocarbons, the atmosphere solute includes at least one of fluoromethane, sodium chloride, and iodoform; and / or When the atmosphere solute contains fatty alcohols, the atmosphere solute includes at least one of 2,2-difluoroethanol, allyl alcohol, and methallyl alcohol; and / or When the atmosphere solute includes compounds containing fatty ethers, the atmosphere solute includes diethyl ether; and / or When the atmosphere solute includes compounds containing fatty acids, the atmosphere solute includes at least one of 2,4-dichlorophenylacetic acid, acetic acid, and acetone; and / or, When the atmosphere solute includes compounds containing fatty amines, the atmosphere solute includes at least one of oleylamine, tetradecylamine, and ethylpropylamine; and / or, When the atmosphere solute includes compounds containing aliphatic thiols, the atmosphere solute includes at least one of isobutyl mercaptan, 2,4-dichlorophenylacetic acid, and methyl mercaptan; and / or When the atmosphere solvent includes alcohol solvents, the atmosphere solvent includes at least one of methanol, ethanol, propanol, butanol, and ethylene glycol; and / or When the atmosphere solvent includes alcohol ether solvents, the atmosphere solvent includes propylene glycol dimethyl ether and ethylene glycol monomethyl ether; and / or The concentration of the atmosphere solute is 5 mg / mL to 10 mg / mL.

10. A light-emitting device, characterized in that, The light-emitting device includes a functional layer, and the functional layer is prepared by the preparation method of the thin film according to any one of claims 4 to 9; or The functional layer is the thin film according to any one of claims 1 to 3.

11. The light-emitting device according to claim 10, characterized in that, The light-emitting device includes a first electrode, a hole functional layer, a light-emitting layer, an electron functional layer, and a second electrode which are sequentially stacked; The electron functional layer includes a first electron functional layer and a second electron functional layer which are sequentially stacked, and the first electron functional layer is located between the light-emitting layer and the second electron functional layer; The material of the first electron functional layer includes first inorganic nanoparticles and a first ligand, and the material of the second electron functional layer includes second inorganic nanoparticles, a second ligand, and a third ligand; Wherein, the first ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group; the third ligand includes at least one of cyano group, hydroxyl group, sulfonic acid group, mercapto group, disulfide group, phosphino group, amino group, carboxyl group, and thiocyanato group; The second ligand includes at least one of a halogen ion, a C1-C24 halogenated hydrocarbon, a C2-C24 fatty alcohol, a C4-C24 fatty ether, a C8-C24 fatty acid, a C8-C24 fatty amine, and a C4-C24 aliphatic mercaptan, and the content of the first ligand in the first electron functional layer is greater than the content of the third ligand in the second electron functional layer.

12. The light-emitting device according to claim 11, characterized in that, The thickness of the first electron functional layer is 10 nm to 30 nm; and / or The thickness of the second electron functional layer is 10 nm to 30 nm; and / or The hydroxyl content in the first ligand of the first electron functional layer is 0.6 to 0.8; and / or The hydroxyl content in the third ligand of the second electron functional layer is 0.2 to 0.5; and / or In the second electron functional layer, the mass ratio of the third ligand to the second ligand is (9 to 16):6; The content of the first ligand in the first electron functional layer is 0.6 to 0.8; and / or The content of the third ligand in the second electron functional layer is 0.2 to 0.5; and / or The first inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS; and / or The second inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, metal sulfides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, HfO3, and Al2O3. The doping elements include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Cd, Cs, and Gd. The metal sulfides include one or more of ZnS, ZnSe, CdS, MoS2, WS2, Cu2S, ZnS, InP, GaP, CuInS2, CuGaS2, and BaTiO3. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

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