Thin film, preparation method thereof and photoelectric device

Abstract

The invention discloses a thin film, a preparation method thereof and a photoelectric device, and relates to the technical field of display. The material of the film comprises inorganic nanoparticles and organic impurities, and the mass fraction of the organic impurities is less than or equal to 1wt%. The thin film provided by the invention is low in organic impurity content.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a thin film, a method for preparing the same, and an optoelectronic device. Background Technology

[0002] Nanoparticles refer to microscopic particles on the nanometer scale, with at least one dimension being smaller than 100 nanometers. Nanoparticles possess characteristics such as small size effect, surface and interface effect, quantum size effect, macroscopic quantum tunneling effect, strong adsorption capacity and chemical activity, and strong permeability, and are widely used in various fields.

[0003] However, the carriers transported in thin films prepared from nanoparticles are prone to quenching, which requires further improvement. Summary of the Invention

[0004] In view of this, this application provides a thin film, a method for preparing the same, and an optoelectronic device.

[0005] The embodiments of this application are implemented as follows: a thin film, the material of which includes inorganic nanoparticles and organic impurities, wherein the mass fraction of the organic impurities is less than or equal to 1 wt%.

[0006] Accordingly, embodiments of this application also provide a method for preparing a thin film, comprising the following steps:

[0007] A first film layer is provided, wherein the material of the first film layer comprises inorganic nanoparticles;

[0008] The first film layer was subjected to ultraviolet irradiation to obtain a thin film.

[0009] Accordingly, this application also provides an optoelectronic device, including an anode, a functional layer and a cathode stacked together, wherein the functional layer includes the thin film described above, or a thin film prepared by the above preparation method.

[0010] The thin film provided in this application has a low content of organic impurities. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of the thin film provided in the embodiments of this application;

[0013] Figure 2 This is a flowchart of the thin film preparation method provided in the embodiments of this application;

[0014] Figure 3 This is a schematic diagram of the structure of the optoelectronic device provided in the embodiments of this application;

[0015] Figure 4 This is a schematic diagram of the structure of another optoelectronic device provided in the embodiments of this application;

[0016] Figure 5 This is a schematic diagram of the structure of another optoelectronic device provided in the embodiments of this application.

[0017] Figure label:

[0018] Optoelectronic devices 100;

[0019] Thin film 10; Hole functional layer 11; Electron functional layer 12; Anode 20; Active layer 30; Cathode 40. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0021] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0022] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0024] 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 merely for convenience and brevity and should not be construed as a hard 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 numerical 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, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0025] In this application, "*" indicates a connection site.

[0026] In related technologies, sol-gel methods are commonly used to prepare nanoparticles. However, the resulting nanoparticles often contain numerous organic impurities on their surface, leading to decreased conductivity and weakened carrier injection and transport. High-temperature annealing is typically used to remove these organic impurities, but this high temperature significantly damages other film layers. Using 172nm excimer UV light in a vacuum environment can remove organic impurities and improve the conductivity of the carrier film. The applicant discovered that UV irradiation of the carrier film significantly increases defects, including oxygen vacancy defects, interstitial metal ion clusters, and metal ion vacancy defects. These defects cause quenching effects and decrease the carrier mobility of the film, affecting its performance.

[0027] The technical solution of this application is as follows:

[0028] Firstly, please refer to Figure 1 This application provides a thin film 10, the material of which includes inorganic nanoparticles and organic impurities, wherein the mass fraction of the organic impurities is less than or equal to 1 wt%.

[0029] It is understandable that during the synthesis of inorganic nanoparticles, organic solvents, organic precipitants, and organic anions from the raw materials are introduced, which can easily remain on the inorganic nanoparticles and affect their conductivity, carrier mobility, and other properties. For example, the organic anions in the raw materials can be acetate ions, etc.; the organic solvents can be one or more of chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol, etc.; the organic precipitants can be one or more of acetone, ethyl acetate, hexane, and heptane, etc.

[0030] It should be noted that the mass fraction of organic impurities refers to the mass of organic impurities / (mass of organic impurities + mass of inorganic nanoparticles) * 100%.

[0031] The thin film 10 provided in this application has a low content of organic impurities, thus avoiding the adverse effects of organic impurities on the conductivity and carrier mobility of inorganic nanoparticles.

[0032] In some embodiments, the mass fraction of the organic impurities in the film can be 0 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or any range between two values. Within this range of organic impurity mass fraction, the adverse effects of organic impurities on the inorganic nanoparticles are avoided.

[0033] It should be noted that in the thin film 10, the organic impurities can exist independently or be attached to the inorganic nanoparticles.

[0034] In some embodiments, the material of the thin film further includes an ionic liquid. The ionic liquid can ionize cations and anions, effectively passivating defects in inorganic nanoparticles, preventing quenching caused by these defects, and improving the overall performance of the thin film 10.

[0035] It should be noted that ionic liquids are liquids composed entirely of ions, generally referring to liquids composed of cations and anions.

[0036] In some embodiments, the cations in the ionic liquid have structural formulas including one or more of the structures shown in the following formulas:

[0037]

[0038] Where n1 and n2 are each independent integers from 1 to 3; R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Each of the substituents is independently selected from one or more of hydrogen, deuterium, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C6-C20 aryl, and substituted or unsubstituted C5-C20 heteroaryl; when substituted, each substituent is independently selected from one or more of deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, mercapto, cyano, C1-C8 alkyl, C1-C8 alkoxy, and C6-C20 aryl; X' is selected from O or S.

[0039] n1 can be 1, 2, or 3. n2 can be 1, 2, or 3.

[0040] In some embodiments, the C1-C20 alkyl group can be C1-C18 alkyl, C1-C15 alkyl, C1-C10 alkyl, C1-C8 alkyl, C1-C6 alkyl, C1-C4 alkyl, C1-C2 alkyl, etc., specifically methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, pentadecyl, octadecyl, eicosyl, etc.

[0041] In some embodiments, the C2-C20 alkoxy group can be C1-C18 alkoxy, C1-C15 alkoxy, C1-C10 alkoxy, C1-C8 alkoxy, C1-C6 alkoxy, C1-C4 alkoxy, C1-C2 alkoxy, etc. Specifically, it can be methoxy, ethoxy, propoxy, butoxy, octoxy, decoxy, dodecyloxy, octadecyloxy, etc.

[0042] In some embodiments, the C6-C20 aryl group can be a C6-C18 aryl group, a C6-C15 aryl group, or a C6-C12 aryl group. Specifically, it can be phenyl, naphthyl, anthraceneyl, phenanthrene, etc.

[0043] In some embodiments, the C5-C20 heteroaryl group can be a C5-C20 heteroaryl group, a C5-C18 heteroaryl group, a C5-C15 heteroaryl group, a C5-C12 heteroaryl group, a C5-C10 heteroaryl group, or a C5-C8 heteroaryl group. Specifically, it can be a thiazolyl, thiophene, furanyl, pyrrole, pyridyl, pyrimidinyl, imidazolyl, pyrazinyl, indolyl, quinolinyl, pteridinyl, acridineyl, etc.

[0044] It is understandable that R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Same or different.

[0045] In some embodiments, R1, R2, R3, R4, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Each is independently selected from C1 to C10 alkyl groups.

[0046] In some embodiments, R5 is selected from one or more of C5-C10 alkyl, C6-C12 aryl, and C5-C10 heteroaryl. R6, R7, and R8 are each independently selected from C1-C4 alkyl.

[0047] In some embodiments, the anions in the ionic liquid include F - Cl - ,Br - I - I3 - BF4 - PF6 - SbF6 - AsF6 - NO2 - NO3 - SCN - CN - HCO3 - HSO4 - H2PO4 - HCOO - CH3COO - CF3COO - CF3SO3 - C4F9SO3 - CF3(C6H4)SO3 - CH3(C6H4)SO3 - (CF3SO2)2N - FeCl4 - (CN)2N -And one or more of 7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate.

[0048] Preferably, the anion in the ionic liquid is selected from CF3SO3. - (CF3SO2)2N - BF4 - FeCl4 - PF6 - SbF6 - (CN)2N - One or more of them.

[0049] In some embodiments, the ionic liquid is selected from one or more of imidazole ionic liquids, pyrrolidine ionic liquids, and quaternary ammonium salt ionic liquids.

[0050] In some embodiments, the imidazole ionic liquid is selected from... (1-Methyl-3-octylimidazolium tetrafluoroborate, MOI-TFB, CAS: 244193-52-0) (1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, EMI-TMS, CAS: 145022-44-2) (1-Ethyl-3-methylimidazoline bis(trifluoromethylsulfonyl)imide, EMI-BTI, CAS: 174899-82-2) (1-Ethyl-3-methylimidazolium diaminonitrile, EMI-DCA, CAS: 370865-89-7) (1-n-Butyl-3-methylimidazolium tetrachloroferrate, BMIM-Cl, CAS: 359845-21-9) (1-n-Butyl-3-methylimidazolium hexafluorophosphate, BMIM-PF6, CAS: 174501-64-5) One or more of (1-n-butyl-3-methylimidazolium hexafluoroantimonate, BMIMPF6, CAS: 174645-81-9).

[0051] In some embodiments, the pyrrolidine ionic liquid is selected from... (1-Butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide, BMP-BTI, CAS: 223437-11-4).

[0052] In some embodiments, the quaternary ammonium salt ionic liquid is selected from... (bis(trifluoromethylsulfonyl)diimide diethylmethyl(2-methoxyethyl)ammonium, CAS: 4649277-84-2).

[0053] In some embodiments, the melting point of the ionic liquid is less than or equal to 25°C, for example, it can be 20°C, 18°C, 15°C, 12°C, 10°C, 8°C, 5°C, 2°C, -3°C, -5°C, -10°C, -15°C, -20°C, etc. Within the range of the melting point, the ionic liquid is liquid at room temperature, has good fluidity, is easy to handle, and is conducive to thorough mixing with inorganic nanoparticles.

[0054] In some embodiments, the average particle size of the inorganic nanoparticles is 2 nm to 15 nm, for example, 5 nm, 8 nm, 10 nm, 12 nm, etc. It should be noted that in this application, the particle size of the inorganic nanoparticles is measured by transmission electron microscopy (TEM).

[0055] In some embodiments, the inorganic nanoparticles include N-type inorganic nanoparticles or P-type inorganic nanoparticles.

[0056] In some embodiments, the N-type inorganic nanoparticles include one or more of a first doped metal oxide particle, a first undoped metal oxide particle, a group IIB-VIA semiconductor material, a group IIIA-VA semiconductor material, and a group IB-IIIA-VIA semiconductor material. The material of the first undoped metal oxide particle includes one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxide in the first doped metal oxide particle includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping element in the first doped metal oxide particle includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The group IIB-VIA semiconductor material includes one or more of ZnS, ZnSe, and CdS. The group IIIA-VA semiconductor material includes one or more of InP and GaP. The group IB-IIIA-VIA semiconductor material includes one or more of CuInS and CuGaS.

[0057] In some embodiments, the P-type inorganic nanoparticles include one or more of a second doped metal oxide particle, a second undoped metal oxide particle, a metal sulfide, a metal selenide, and a metal nitride. The metal oxide in the second doped metal oxide particle and the metal oxide in the second undoped metal oxide particle each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, and V2O5. The doping element in the second doped metal oxide particle includes one or more of Mo, W, Ni, Cr, Cu, and V. The metal sulfide includes one or more of CuS, MoS3, and WS3. The metal selenide includes one or more of MoSe3 and WSe3. The metal nitride includes P-type gallium nitride.

[0058] In some embodiments, the inorganic nanoparticles are inorganic nanoparticles that have undergone ultraviolet irradiation treatment. Typically, organic impurities remain on the surface of inorganic nanoparticles. Ultraviolet irradiation treatment can effectively remove these organic impurities, but it also increases surface defects in the inorganic nanoparticles. Adding ionic liquids can effectively improve these defects and enhance the overall performance of the film 10.

[0059] Furthermore, the wavelength of the ultraviolet irradiation is 165±10nm, for example, it can be 155nm, 158nm, 160nm, 162nm, 165nm, 168nm, 170nm, 172nm, etc. Within this wavelength range, the energy of ultraviolet light can break the major bonds of organic molecules. Organic impurities, after being excited by ultraviolet radiation, will generate high-energy oxygen free radicals and ozone, which are then removed.

[0060] The intensity of the ultraviolet irradiation was 20 mW / cm². 2 ~200mW / cm 2 For example, it can be 30mW / cm 2 50mW / cm 2 80mW / cm 2 100mW / cm 2 120mW / cm 2 150mW / cm 2 180mW / cm 2 The time is 10 min to 50 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, etc. Under the aforementioned ultraviolet irradiation conditions, organic impurities located on the surface of inorganic nanoparticles can be effectively removed, thereby improving the carrier mobility of the thin film 10.

[0061] In some embodiments, the mass-to-volume ratio of the inorganic nanoparticles to the ionic liquid in the thin film 10 is (5-20) mg:1 mL, for example, 6 mg:1 mL, 8 mg:1 mL, 10 mg:1 mL, 12 mg:1 mL, 15 mg:1 mL, 18 mg:1 mL, etc. Within this mass-to-volume ratio range, it is beneficial for the ionic liquid to fully wet the inorganic nanoparticles and improve the defects of the inorganic nanoparticles.

[0062] In some embodiments, in the thin film 10, the ionic liquid and the inorganic nanoparticles are connected by coordination bonds. The ionic liquid coats the surface of the inorganic nanoparticles in the form of a liquid film. Part of the ionic liquid may also fill the gaps between adjacent inorganic nanoparticles.

[0063] In some embodiments, the thickness of the thin film 10 is 20 nm to 80 nm, for example, it can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, etc. It should be noted that in this application, the thickness of the film layer is measured using a step tester.

[0064] Secondly, please refer to Figure 2 This application also provides a method for preparing a thin film 10, comprising the following steps:

[0065] S11. A first film layer is provided, wherein the material of the first film layer includes inorganic nanoparticles;

[0066] S12. The first film layer is subjected to ultraviolet irradiation treatment to obtain film 10.

[0067] In S11:

[0068] In some embodiments, the material of the first film layer further includes organic impurities. It is understood that during the synthesis of inorganic nanoparticles, organic solvents and organic anions from the raw materials are introduced, which can easily remain on the inorganic nanoparticles, affecting their conductivity, carrier mobility, and other properties.

[0069] Furthermore, in the first film layer, the mass fraction of the organic impurities is 1 wt% to 5 wt%, for example, it can be 2 wt%, 3 wt%, 4 wt%, etc. It is understood that conventional methods for synthesizing inorganic nanoparticles introduce organic impurities, affecting the performance of the inorganic nanoparticles.

[0070] The average particle size, material, and organic impurity material of the inorganic nanoparticles are described above and will not be repeated here.

[0071] In some embodiments, the method for preparing the first film layer includes:

[0072] An inorganic nanoparticle dispersion is provided, wherein the inorganic nanoparticle dispersion comprises inorganic nanoparticles and a first solvent;

[0073] The inorganic nanoparticle dispersion is deposited to obtain the first film layer.

[0074] In some embodiments, the inorganic nanoparticle dispersion has a mass concentration of 15 mg / mL to 30 mg / mL, for example, 16 mg / mL, 18 mg / mL, 20 mg / mL, 22 mg / mL, 25 mg / mL, 28 mg / mL, etc. Within this mass concentration range, the dissolution and dispersion of the inorganic nanoparticles in the first solvent are beneficial.

[0075] In some embodiments, the first solvent includes one or more of chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol.

[0076] In some embodiments, the first film layer is a wet film. In other words, no annealing or other operations are performed after the inorganic nanoparticle dispersion is deposited.

[0077] In S12:

[0078] In some embodiments, the wavelength of the ultraviolet irradiation is 172 nm. The energy of ultraviolet light with a wavelength of 172 nm can break the major bonds of organic molecules. Organic impurities, when excited by ultraviolet radiation with a wavelength of 172 nm, will generate high-energy oxygen free radicals and ozone, which are then removed.

[0079] In some embodiments, the intensity of the ultraviolet irradiation is 20 mW / cm². 2 ~200mW / cm 2 For example, it can be 30mW / cm 2 50mW / cm 2 80mW / cm 2 100mW / cm 2 120mW / cm 2 150mW / cm 2 180mW / cm 2 The time is 10 min to 50 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, etc. Under the aforementioned ultraviolet irradiation conditions, organic impurities located on the surface of inorganic nanoparticles can be effectively removed, thereby improving the carrier mobility of the thin film 10.

[0080] In some embodiments, the ultraviolet irradiation treatment is performed under vacuum conditions.

[0081] The ultraviolet irradiation treatment can be performed using an ultraviolet excimer lamp.

[0082] Ultraviolet irradiation removes organic impurities, but exposes more defects in inorganic nanoparticles, which are prone to quenching.

[0083] In some embodiments, after the first film layer is subjected to ultraviolet irradiation treatment, an intermediate film is obtained; after obtaining the intermediate film and before obtaining the thin film, the method further includes: providing an ionic liquid and disposing the ionic liquid on the intermediate film.

[0084] The ionic liquids mentioned above will not be repeated here.

[0085] In some embodiments, the step of disposing the ionic liquid on the intermediate membrane includes:

[0086] An ionic liquid dispersion is provided, the ionic liquid dispersion comprising an ionic liquid and a second solvent;

[0087] The ionic liquid dispersion is placed on the intermediate membrane to obtain the thin film 10.

[0088] It is understood that the ionic liquid dispersion is disposed on the intermediate membrane to allow the ionic liquid to permeate into the intermediate membrane. The first membrane layer is a wet membrane, which facilitates the diffusion of the ionic liquid into the gaps between the inorganic nanoparticles.

[0089] In some embodiments, the volume ratio of the ionic liquid to the second solvent in the ionic liquid dispersion is 1:(10-200), for example, 1:30, 1:50, 1:80, 1:100, 1:120, 1:150, 1:160, 1:180, etc. Within the range of the stated volume ratio, the ionic liquid and the second solvent are mixed uniformly, and when the ionic liquid dispersion is placed on the intermediate film, it facilitates the rapid diffusion of the ionic liquid into the intermediate film by the second solvent.

[0090] In some embodiments, the second solvent includes one or more of chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol.

[0091] It should be noted that the first solvent and the second solvent may be made of the same or different materials. Preferably, the first solvent and the second solvent are made of the same material, which facilitates the diffusion of the second solvent carrying the ionic liquid into the gaps between the inorganic nanoparticles, ensuring uniform and sufficient contact with the inorganic nanoparticles.

[0092] In some embodiments, after the ionic liquid dispersion is placed on the intermediate membrane, the time for the ionic liquid to permeate into the intermediate membrane is 20s to 90s, for example, 30s, 40s, 50s, 60s, 70s, 80s, etc. Within this time range, the ionic liquid can fully diffuse into the gaps between the inorganic nanoparticles, passivating the defects of the inorganic nanoparticles.

[0093] It should be noted that after the ionic liquid permeates into the intermediate membrane, the ionic liquid that has not diffused into the intermediate membrane can be removed by rotating the thin film 10.

[0094] In some embodiments, after the ionic liquid dispersion is placed on the intermediate membrane, annealing is further included.

[0095] Furthermore, the annealing temperature is 50℃ to 90℃, for example, it can be 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, etc.; the annealing time is 2min to 10min, for example, it can be 3min, 4min, 5min, 6min, 7min, 8min, 9min, etc. Thus, under the annealing conditions, it is beneficial to remove the first solvent and the second solvent, improve the film-forming properties of the film 10, and reduce the loss of ionic liquid.

[0096] Thirdly, please refer to Figure 3 This application also provides an optoelectronic device 100, which includes an anode 20, a functional layer and a cathode 40 stacked together. The functional layer includes the thin film 10 described above, or includes the thin film 10 prepared by the above preparation method.

[0097] In some embodiments, please refer to Figure 4 The functional layer includes a hole functional layer 11, which includes the above-described thin film 10, or includes the thin film 10 prepared by the above-described preparation method.

[0098] In some embodiments, please refer to Figure 5 The functional layer includes an electronic functional layer 12, which includes the thin film 10 described above, or includes the thin film 10 prepared by the above preparation method.

[0099] It is understood that the functional layer may also include both a hole functional layer 11 and an electron functional layer 12, wherein the hole functional layer 11 and the electron functional layer 12 are the aforementioned thin films.

[0100] In some embodiments, the functional layer further includes an active layer 30, the hole functional layer 11 is located between the anode 20 and the active layer 30, and the electron functional layer 12 is located between the active layer 30 and the cathode 40.

[0101] The optoelectronic device 100 provided in this application has an ionic liquid in the thin film 10 that can effectively improve the defects of inorganic nanoparticles, avoid quenching of charge carriers after they enter the active layer 30, and improve the efficiency and stability of the optoelectronic device 100.

[0102] The hole functional layer 11 includes one or more of a hole injection layer and a hole transport layer.

[0103] The electronic functional layer 12 includes one or more of an electron injection layer and an electron transport layer.

[0104] It should be noted that when the hole functional layer 11 includes the aforementioned thin film 10, the inorganic nanoparticles in the thin film 10 are P-type inorganic nanoparticles; when the electron functional layer 12 includes the aforementioned thin film 10, the inorganic nanoparticles in the thin film 10 are N-type inorganic nanoparticles.

[0105] It should also be noted that when the hole functional layer 11 includes the aforementioned thin film 10, the material of the electronic functional layer 12 can be N-type inorganic nanoparticles; in other words, the material in the electronic functional layer 12 does not contain ionic liquids. When the electronic functional layer 12 includes the aforementioned thin film 10, the material of the hole functional layer 11 can be P-type inorganic nanoparticles or P-type organic semiconductors. The P-type organic semiconductors include 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, and N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent materials, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diphenylbenzidine] [4,4'-(N-(4-sec-butylphenyl)diphenylamine)], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-)phenylenevinylene, poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], copper phthalocyanine, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4 One or more of the following: '-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthyl-1-yl)-N,N'-diphenylbenzidine, spironolactone (NPB), microcrystalline cellulose, and tetracyanoquinone dimethylethane.

[0106] In some embodiments, the active layer 30 includes a light-emitting layer, the material of which includes a light-emitting material, and the light-emitting material includes one or more of organic light-emitting materials and quantum dot light-emitting materials.

[0107] The organic light-emitting material may be selected from, but is not limited to, one or more of the following: CBP:Ir(mppy)3(4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III)]), TCTX:Ir(mmpy)(4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium(III)]), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescent materials, TTA materials, TADF (thermally activated delayed) materials, polymers containing BN covalent bonds, HLCT (hybrid local charge transfer excited state) materials, and Exciplex (excitoplex) light-emitting materials.

[0108] The quantum dot luminescent material may be selected from, but is not limited to, one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite quantum dots.

[0109] The materials for the single-structure quantum dots, the core material of the core-shell quantum dots, and the shell material of the core-shell quantum dots can be selected from, but are not limited to, one or more compounds from group II-VI, group IV-VI, group III-V, and group I-III-VI. The shell of the core-shell quantum dots may consist of one or more layers. The group II-VI compounds may be selected from, but are not limited to, one or more of 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, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The IV-VI group compounds may be selected from, but are not limited to, one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The group III-V compounds may be selected from, but are not limited to, one or more of 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. The group I-III-VI compounds may be selected from, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2.

[0110] As an example, the core-shell structured quantum dots can be selected from, but are not limited to, one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS. In the above descriptions of CdSe / ZnS, etc., the " / " indicates that the material after the " / " (as the shell) covers the material before the " / " (as the core).

[0111] The materials used for the perovskite quantum dots can be selected from, but are not limited to, doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors. The general structural formula of the inorganic perovskite semiconductor is AMX"3, where A is Cs. + Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2 + Yb 2+ Eu 2+ One or more of the following, where "X" is a halide anion selected from Cl... - ,Br - I - One or more of the following. The general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX"3, where B is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2 + Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where "X" is a halide anion selected from Cl... -,Br - I - One or more of them.

[0112] In some embodiments, the anode 20 and the cathode 40 each independently comprise one or more of a metal, a carbon material, and a metal oxide; the metal comprises one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material comprises one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxide comprises a metal oxide electrode or a composite electrode in which a metal is disposed between doped or undoped transparent metal oxides, the material of the metal oxide electrode comprising one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO; the composite electrode comprises one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. In this context, " / " indicates a stacked structure. For example, AZO / Ag / AZO represents a composite electrode consisting of sequentially stacked AZO, Ag, and AZO layers.

[0113] This application embodiment also provides a display device, which includes the above-described optoelectronic device 100.

[0114] The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0115] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0116] Example 1

[0117] This embodiment provides a thin film, prepared by the following method:

[0118] An ethanol dispersion of ZnO is provided, with a ZnO mass concentration of 20 mg / mL. Zinc acetate is used as the zinc source and ethanol as the organic solvent in the ZnO synthesis process, resulting in organic impurities attached to the ZnO surface (the mass fraction of organic impurities was 4 wt% according to thermogravimetric analysis). The ethanol dispersion of ZnO is spin-coated at a speed of 4000 rpm for 30 s to form the first film layer.

[0119] The first film layer was irradiated with an ultraviolet excimer lamp at a wavelength of 172 nm and an intensity of 50 mW / cm². 2 The irradiation time was 30 min to form a thin film (thermogravimetric analysis showed that the mass fraction of organic impurities on the ZnO surface in the thin film was 0.05 wt%).

[0120] Example 2

[0121] This embodiment is basically the same as Embodiment 1, except that the film formed in Embodiment 1 is an intermediate film. The method for forming the film further includes: adding an ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to the intermediate film, wherein the volume ratio of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to ethanol is 1:50, wetting for 60 seconds, then removing the excess ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate at 8000 rpm, and annealing at 80°C for 5 minutes to obtain the film.

[0122] Example 3

[0123] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-ethyl-3-methylimidazoline bis(trifluoromethanesulfonyl)imine.

[0124] Example 4

[0125] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide.

[0126] Example 5

[0127] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-ethyl-3-methylimidazolium diaminonitrile in this embodiment.

[0128] Example 6

[0129] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-methyl-3-octylimidazolium tetrafluoroborate.

[0130] Example 7

[0131] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium tetrachloroferrate in this embodiment.

[0132] Example 8

[0133] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium hexafluorophosphate in this embodiment.

[0134] Example 9

[0135] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium hexafluoroantimonate.

[0136] Example 10

[0137] This embodiment is basically the same as Embodiment 2, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with bis(trifluoromethanesulfonyl)diimide diethylmethyl(2-methoxyethyl)ammonium.

[0138] Example 11

[0139] This embodiment is basically the same as Embodiment 2, except that the intensity of ultraviolet irradiation in this embodiment is 200mW / cm². 2 The time is 10 minutes.

[0140] Example 12

[0141] This embodiment is basically the same as Embodiment 2, except that the intensity of ultraviolet irradiation in this embodiment is 20mW / cm². 2 The time is 50 minutes.

[0142] Example 13

[0143] This embodiment is basically the same as Embodiment 2, except that the annealing temperature in this embodiment is 90°C and the time is 2 minutes.

[0144] Example 14

[0145] This embodiment is basically the same as Embodiment 2, except that the annealing temperature in this embodiment is 50°C and the time is 10 minutes.

[0146] Example 15

[0147] This embodiment provides a thin film, prepared by the following method:

[0148] An ethanol dispersion of NiO with a mass concentration of 20 mg / mL is provided. The mixture is then spin-coated at a speed of 4000 rpm for 30 seconds to form the first film layer.

[0149] The first film layer was irradiated with an ultraviolet excimer lamp at a wavelength of 172 nm and an intensity of 50 mW / cm². 2 The irradiation time is 30 minutes to form a thin film.

[0150] Example 16

[0151] This embodiment is basically the same as that of embodiment 15, except that the film formed in embodiment 15 is an intermediate film. The method for forming the film further includes: adding an ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to the intermediate film, wherein the volume ratio of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to ethanol is 1:50, wetting for 60 seconds, then removing the excess ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate at 8000 rpm, and annealing at 80°C for 5 minutes to obtain the film.

[0152] Example 17

[0153] This embodiment is basically the same as Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine.

[0154] Example 18

[0155] This embodiment is basically the same as that of Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imide.

[0156] Example 19

[0157] This embodiment is basically the same as that of Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-ethyl-3-methylimidazolium diaminonitrile in this embodiment.

[0158] Example 20

[0159] This embodiment is basically the same as Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-methyl-3-octylimidazolium tetrafluoroborate in this embodiment.

[0160] Example 21

[0161] This embodiment is basically the same as that of Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium tetrachloroferrate in this embodiment.

[0162] Example 22

[0163] This embodiment is basically the same as that of Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium hexafluorophosphate in this embodiment.

[0164] Example 23

[0165] This embodiment is basically the same as Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with 1-n-butyl-3-methylimidazolium hexafluoroantimonate.

[0166] Example 24

[0167] This embodiment is basically the same as Embodiment 16, except that 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is replaced with bis(trifluoromethanesulfonyl)diimide diethylmethyl(2-methoxyethyl)ammonium.

[0168] Comparative Example 1

[0169] This comparative example provides a thin film, which is the first film layer of Example 1.

[0170] Comparative Example 2

[0171] This comparative example is basically the same as Example 2, except that the first film layer was not subjected to ultraviolet irradiation treatment in this comparative example, and the ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was directly added to the first film layer.

[0172] Comparative Example 3

[0173] This comparative example provides a thin film, which is the first film layer of Example 15.

[0174] Comparative Example 4

[0175] This comparative example is basically the same as Example 16, except that the first film layer was not subjected to ultraviolet irradiation treatment in this comparative example, and the ethanol dispersion of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was directly added to the first film layer.

[0176] The carrier mobility of the thin films in Examples 1-24 and Comparative Examples 1-4 was tested respectively, where Examples 1-14 and Comparative Examples 1-2 were electron mobility, and Examples 15-24 and Comparative Examples 3-4 were hole mobility. The results are shown in Table 1.

[0177] The carrier mobility test method is as follows: The current density-voltage curve of the optoelectronic device (single carrier transport thin film device HOD / EOD) is measured. The EOD structure is anode / quantum dot emitting layer / electron transport layer (thin films of Examples 1-14 and Comparative Examples 1-2) / cathode, and the HOD structure is anode / hole transport layer (thin films of Examples 15-24 and Comparative Examples 3-4) / quantum dot emitting layer / cathode. The space charge confinement current (SCLC) region in the current density-voltage curve is obtained, and then the value is calculated according to the formula J = (9 / 8)ε. r ε0μ e V 2 / d 3 Calculate the electron / hole mobility, where J represents the current density in mA / cm². -2 ;ε r ε₀ represents the relative permittivity, and μ represents the vacuum permittivity. e Electron / hole mobility is expressed in cm. 2 V -1 s -1 V represents the driving voltage, with units of V; d represents the film thickness, with units of m.

[0178] Table 1

[0179]

[0180]

[0181] From Table 1, we can obtain:

[0182] As can be seen from Examples 1-14 and Comparative Examples 1-2, ultraviolet irradiation treatment of the first film layer made of N-type inorganic nanoparticles can significantly improve the electron mobility of the film. Adding ionic liquid to the film alone will slightly decrease the electron mobility of the film. Adding ionic liquid to the film after ultraviolet irradiation treatment can significantly improve the electron mobility compared to Comparative Example 1.

[0183] As can be seen from Examples 15-24 and Comparative Examples 3-4, ultraviolet irradiation treatment of the first film layer made of P-type inorganic nanoparticles can significantly improve the hole mobility of the film. Adding ionic liquid to the film alone will slightly decrease the hole mobility of the film. Adding ionic liquid to the film after ultraviolet irradiation treatment can significantly improve the hole mobility compared to Comparative Example 3.

[0184] Device Example 1

[0185] This embodiment provides an optoelectronic device, the fabrication method of which is as follows:

[0186] The ITO conductive glass was cleaned with a cleaning agent to initially remove the stains on the surface. Then, it was ultrasonically cleaned for 20 minutes each in deionized water, acetone, anhydrous ethanol, and deionized water to remove the impurities on the surface. Finally, it was dried with high-purity nitrogen to form an ITO anode with a thickness of 100 nm.

[0187] An ethanol dispersion of NiO was spin-coated onto an ITO anode at a speed of 3000 rpm for 30 seconds, followed by baking at 150°C for 20 minutes to form a hole transport layer.

[0188] An octane dispersion of CdSe / ZnS core-shell quantum dots with a concentration of 20 mg / mL was spin-coated onto the hole transport layer at a speed of 3000 rpm for 30 s, followed by baking at 100 °C for 5 min to form a luminescent layer.

[0189] A thin film was prepared on the light-emitting layer as described in Example 1 to form an electron transport layer;

[0190] Ag was thermally evaporated onto the electron transport layer at a vacuum level not exceeding 3 × 10⁻⁶. -4 Pa, velocity of 1 angstrom / second, time of 1000s, forming a cathode with a thickness of 100nm;

[0191] Packaging yields optoelectronic devices.

[0192] Device Examples 2-14

[0193] Device Examples 2-14 are basically the same as Device Example 1, except that thin films are prepared in Device Examples 2-14 respectively to form electron transport layers.

[0194] Device Example 15

[0195] Device Example 15 is basically the same as Device Example 1, except that in Device Example 15, a thin film is prepared in accordance with Example 15 to form a hole transport layer;

[0196] The method for preparing the electron transport layer includes: spin-coating an ethanol dispersion of ZnO at a spin speed of 3000 rpm for 30 s, followed by baking at 80°C for 30 min to form the electron transport layer.

[0197] Device Examples 16-24

[0198] Device Examples 16-24 are basically the same as Device Example 1, except that thin films are prepared in Device Examples 16-24 respectively to form hole transport layers.

[0199] Device Example 25

[0200] Device Example 25 is basically the same as Device Example 1, except that in Device Example 25, a thin film is prepared in accordance with Example 16 to form a hole transport layer.

[0201] Device Example 26

[0202] Device Example 26 is basically the same as Device Example 1, except that in Device Example 26, a thin film is prepared in accordance with Example 15 to form a hole transport layer.

[0203] Device Example 27

[0204] Device Example 27 is basically the same as Device Example 1, except that in Device Example 27, a thin film is prepared in accordance with Example 17 to form a hole transport layer.

[0205] Device Comparison Examples 1-2

[0206] The devices in Comparative Examples 1 and 2 are basically the same as those in Device Example 1, except that thin films are prepared in Comparative Examples 1 and 2 respectively to form electron transport layers.

[0207] Device Comparison Example 3

[0208] Device Comparative Example 3 is basically the same as Device Example 16, except that in Device Comparative Example 3, a thin film is prepared in accordance with Comparative Example 4 to form a hole transport layer.

[0209] Device Comparison Example 4

[0210] Device Comparative Example 4 is basically the same as Device Comparative Example 2, except that in Device Comparative Example 4, a thin film is prepared in accordance with Comparative Example 4 to form a hole transport layer.

[0211] The transient fluorescence lifetime of quantum dots in the optoelectronic devices of Device Examples 1-27 and Device Comparative Examples 1-4 were tested respectively, as well as the external quantum efficiency EQE and lifetime T95@1000nit of the optoelectronic devices. The results are shown in Table 2.

[0212] The transient fluorescence lifetime of the quantum dots was measured using an FLS 980 steady-state / transient fluorescence spectrometer.

[0213] External quantum efficiency (EQE) is measured as the ratio of electron-hole pairs injected into a quantum dot to the number of emitted photons, expressed as a percentage (%). It is an important parameter for evaluating the quality of electroluminescent devices and can be obtained using an EQE optical testing instrument. The specific calculation formula is as follows:

[0214]

[0215] Where, η e For optical output coupling efficiency, η rχ is the ratio of recombination carriers to injected carriers, and K is the ratio of excitons producing photons to the total number of excitons. R K is the radiation process rate. NR This represents the rate of a non-radiative process.

[0216] Test conditions: Conducted at room temperature with an air humidity of 30-60%.

[0217] The measurement method for lifetime T95@1000nit is as follows: Under constant current or voltage drive, the time required for the brightness of the device to decrease to a certain percentage of its maximum brightness is defined as T95. This lifetime is the measured lifetime. To shorten the testing cycle, device lifetime testing is usually performed at high brightness by accelerating device aging, and the lifetime at high brightness is obtained by fitting an extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000nit is measured as T95@1000nit. The specific calculation formula is as follows:

[0218]

[0219] Among them, T95 L For longer lifespan at low brightness, T95 H For the measured lifetime under high brightness, L H To accelerate the device to its maximum brightness, L L The value is 1000 nits, and A is the acceleration factor. In this experiment, the lifetime of several groups of QLED devices under rated brightness was measured, and the value of A was found to be 1.7.

[0220] Table 2

[0221]

[0222]

[0223] As shown in Table 2:

[0224] As can be seen from Device Examples 1-14 and Device Comparative Examples 1-4, although ultraviolet irradiation can significantly improve the electron mobility of thin films containing N-type inorganic nanoparticles, it also leads to an increase in defects in the N-type inorganic nanoparticles, causing fluorescence quenching and resulting in a sharp decrease in the transient fluorescence lifetime of quantum dots. In this application, after improving the electron mobility of the thin film by ultraviolet treatment, an ionic liquid is further added, which effectively improves the defects caused by ultraviolet treatment, improves the overall performance of the thin film, and thus improves the external quantum efficiency and lifespan of optoelectronic devices.

[0225] As can be seen from Device Examples 15-24 and Device Comparative Examples 1-4, although ultraviolet irradiation can significantly improve hole mobility in thin films containing P-type inorganic nanoparticles, it also leads to an increase in defects in the P-type inorganic nanoparticles, causing fluorescence quenching and resulting in a sharp decrease in the transient fluorescence lifetime of quantum dots. This application improves hole mobility by ultraviolet treatment of the thin film and then further incorporates an ionic liquid, which effectively improves the defects caused by ultraviolet treatment, improves the overall performance of the thin film, and thus improves the external quantum efficiency and lifespan of optoelectronic devices.

[0226] As can be seen from device examples 25-27 and device comparative examples 1-4, simultaneously irradiating both the electron functional layer and the hole functional layer in the optoelectronic device with ultraviolet light and adding an ionic liquid can significantly improve the defects of the charge carrier thin film, enhance the overall performance of the charge carrier thin film, reduce fluorescence quenching, promote the effective recombination of holes and electrons, improve the transient fluorescence lifetime of quantum dots, improve the external quantum efficiency of the optoelectronic device, and extend the service life of the optoelectronic device.

[0227] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A thin film, characterized in that, The material of the film includes inorganic nanoparticles and organic impurities, wherein the mass fraction of the organic impurities is less than or equal to 1 wt%.

2. The thin film as described in claim 1, characterized in that, The material of the thin film also includes ionic liquids; Optionally, the cation in the ionic liquid has a structural formula including one or more of the structures shown in the following formulas: Where n1 and n2 are each independent integers from 1 to 3; R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Each of the following groups is independently selected from one or more of hydrogen, deuterium, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C6-C20 aryl, and substituted or unsubstituted C5-C20 heteroaryl; when substituted, each substituent is independently selected from one or more of deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, mercapto, cyano, C1-C8 alkyl, C1-C8 alkoxy, and C6-C20 aryl; X' is selected from O or S; and / or The anions in the ionic liquid include F. - Cl - ,Br - I - I3 - BF4 - PF6 - SbF6 - AsF6 - NO2 - NO3 - SCN - CN - HCO3 - HSO4 - H2PO4 - HCOO - CH3COO - CF3COO - CF3SO3 - C4F9SO3 - CF3(C6H4)SO3 - CH3(C6H4)SO3 - (CF3SO2)2N - FeCl4 - (CN)2N - And one or more of 7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate.

3. The thin film as described in claim 2, characterized in that, In the thin film, the mass ratio of the inorganic nanoparticles to the volume of the ionic liquid is (5-20) mg:1 mL; and / or The melting point of the ionic liquid is less than or equal to 25°C; and / or R1 and R2 may be the same or different; and / or R3 and R4 may be the same or different; and / or R9 and R 10 Same or different; and / or R 12 and R 13 Same or different; and / or R 14 and R 15 Same or different; and / or R6 and R 17 Same or different; and / or R1, R2, R3, R4, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Each is independently selected from C1 to C10 alkyl groups; and / or R5 is selected from one or more of C5-C10 alkyl, C6-C12 aryl, and C5-C10 heteroaryl; and / or R6, R7, and R8 are each independently selected from C1 to C4 alkyl groups; and / or The anions in the ionic liquid are selected from CF3SO3. - (CF3SO2)2N - BF4 - FeCl4 - PF6 - SbF6 - (CN)2N - One or more of them.

4. The thin film as described in claim 2, characterized in that, The ionic liquid is selected from one or more of imidazole ionic liquids, pyrrolidine ionic liquids, and quaternary ammonium salt ionic liquids; Optionally, the imidazole ionic liquid is selected from one or more compounds having the following structural formula: Optionally, the pyrrolidine ionic liquid is selected from compounds having the following structural formula: Optionally, the quaternary ammonium salt ionic liquid is selected from compounds having the following structural formula:

5. The thin film as claimed in claim 1, characterized in that, In the film, the mass fraction of the organic impurities is less than or equal to 0.1 wt%; and / or The thickness of the thin film is 20 nm to 80 nm; and / or The inorganic nanoparticles have an average particle size of 2 nm to 15 nm; and / or The inorganic nanoparticles include N-type inorganic nanoparticles or P-type inorganic nanoparticles; and / or The inorganic nanoparticles are inorganic nanoparticles that have undergone ultraviolet irradiation treatment.

6. The thin film as described in claim 5, characterized in that, The N-type inorganic nanoparticles include one or more of the following: first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The first undoped metal oxide particles are composed of one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles are composed of one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles are composed of one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials are composed of one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials are composed of one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials are composed of one or more of CuInS and CuGaS; and / or The p-type inorganic nanoparticles include one or more of the following: second-doped metal oxide particles, second-undoped metal oxide particles, metal sulfides, metal selenides, and metal nitrides. The metal oxides in the second-doped and second-undoped metal oxide particles each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, and V2O5. The doping element in the second-doped metal oxide particles includes one or more of Mo, W, Ni, Cr, Cu, and V. The metal sulfide includes one or more of CuS, MoS3, and WS3. The metal selenide includes one or more of MoSe3 and WSe3. The metal nitride includes p-type gallium nitride; and / or The wavelength of the ultraviolet irradiation is 172 nm; and / or The intensity of the ultraviolet irradiation was 20 mW / cm². 2 ~200mW / cm 2 The time is 10 min to 50 min.

7. A method for preparing a thin film, characterized in that, Includes the following steps: Provide a first film layer comprising inorganic nanoparticles; The first film layer was subjected to ultraviolet irradiation to obtain a thin film.

8. The preparation method according to claim 7, characterized in that, After subjecting the first film layer to ultraviolet irradiation treatment, an intermediate film is obtained; after obtaining the intermediate film and before obtaining the thin film, the method further includes: providing an ionic liquid and disposing the ionic liquid on the intermediate film; wherein... The cations in the ionic liquid have structural formulas including one or more of the following: Where n1 and n2 are each independent integers from 1 to 3; R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 Each of the following groups is independently selected from one or more of hydrogen, deuterium, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C6-C20 aryl, and substituted or unsubstituted C5-C20 heteroaryl; when substituted, each substituent is independently selected from one or more of deuterium, amino, halogen, hydroxyl, carboxyl, nitro, sulfonic acid, mercapto, cyano, C1-C8 alkyl, C1-C8 alkoxy, and C6-C20 aryl; X' is selected from O or S; and / or The anions in the ionic liquid include F. - Cl - ,Br - I - I3 - BF4 - PF6 - SbF6 - AsF6 - NO2 - NO3 - SCN - CN - HCO3 - HSO4 - H2PO4 - HCOO - CH3COO - CF3COO - CF3SO3 - C4F9SO3 - CF3(C6H4)SO3 - CH3(C6H4)SO3 - (CF3SO2)2N - FeCl4 - (CN)2N - And one or more of 7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate; and / or The material of the first film layer also includes organic impurities, wherein the mass fraction of the organic impurities is 1 wt% to 5 wt%; and / or The first film layer is a wet film; and / or The wavelength of the ultraviolet irradiation is 165±10nm; and / or The intensity of the ultraviolet irradiation was 20 mW / cm². 2 ~200mW / cm 2 The time is 10 min to 50 min; and / or The ultraviolet irradiation treatment is performed under vacuum conditions; and / or The step of setting the ionic liquid on the intermediate membrane includes: providing an ionic liquid dispersion, the ionic liquid dispersion comprising an ionic liquid and a second solvent; and setting the ionic liquid dispersion on the intermediate membrane to obtain a thin film.

9. The preparation method according to claim 8, characterized in that, In the ionic liquid dispersion, the volume ratio of the ionic liquid to the second solvent is 1: (10–200); and / or The second solvent comprises one or more of the following: chlorobenzene, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol; and / or After the ionic liquid dispersion is placed on the intermediate membrane, the time for the ionic liquid to permeate into the intermediate membrane is 20s to 90s; and / or After the ionic liquid dispersion is placed on the intermediate membrane, the process further includes annealing; the annealing temperature is 50℃~90℃ and the time is 2min~10min.

10. An optoelectronic device, characterized in that, It includes an anode, a functional layer, and a cathode stacked together, wherein the functional layer includes a thin film as described in any one of claims 1 to 6, or a thin film prepared by the preparation method as described in any one of claims 7 to 9.

11. The optoelectronic device as described in claim 10, characterized in that, The functional layer includes a hole-functional layer, the hole-functional layer includes the thin film, and the inorganic nanoparticles in the thin film are p-type inorganic nanoparticles; and / or The functional layer includes an electronic functional layer, which includes the thin film, wherein the inorganic nanoparticles in the thin film are N-type inorganic nanoparticles.

12. The optoelectronic device as described in claim 11, characterized in that, The functional layer includes an active layer, the hole functional layer is located between the anode and the active layer, and the electron functional layer is located between the active layer and the cathode; the active layer includes a light-emitting layer, the material of which includes one or more of organic light-emitting materials and quantum dot light-emitting materials; the organic light-emitting material is selected from 4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III)], 4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium(III)], diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene Derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescence materials, TTA materials, TADF materials, polymers containing BN covalent bonds, HLCT materials, and Exciplex luminescent materials are selected from one or more of the following: The quantum dot luminescent material is selected from one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite quantum dots; the material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are respectively selected from group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I- One or more of group III-VI compounds; the shell of the core-shell quantum dot comprises one or more layers; the group II-VI compound is selected from 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, HgZnS, HgZnSe, HgZnTe The compounds are selected from one or more of the following: CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI compounds are selected from one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe.The III-V compounds are selected from one or more of 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. The I-III-VI group compounds are selected from one or more of CuInS2, CuInSe2, and AgInS2; the core-shell quantum dots are selected from one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS; the perovskite quantum dots are made of doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX"3, where A is Cs; + Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where "X" is a halide anion selected from Cl... - ,Br - I - One or more of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX"3, where B is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2 + Yb 2+ Eu 2+ One or more of the following, where "X" is a halide anion selected from Cl... - ,Br - I - One or more of the following; and / or The anode and the cathode each independently comprise one or more of a metal, a carbon material, and a metal oxide; the metal comprises one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material comprises one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxide comprises a metal oxide electrode or a composite electrode in which a metal is disposed between doped or undoped transparent metal oxides; the material of the metal oxide electrode comprises one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO; the composite electrode comprises one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2.

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