Thin film and preparation method thereof, light-emitting device and display device

Abstract

The invention discloses a thin film and a preparation method thereof, a light-emitting device and a display device, and the preparation method comprises the steps: providing a quantum solution, and forming a film layer through a film forming technology; according to the preparation method of the thin film, plasma treatment is carried out on the film layer through plasmas, the thin film is obtained, and the plasmas comprise water plasmas. The OH free radicals and the O free radicals can fully oxidize and separate the long-chain ligands on the surfaces of the quantum dots, so that the long-chain ligands on the surfaces of the quantum dots are removed, further, after the long-chain ligands on the surfaces of the quantum dots are removed, the defects on the surfaces of the quantum dots are increased, and the OH free radicals and the O free radicals can passivate the surface defects, so that the defects on the surfaces of the quantum dots are reduced. And the quantum dots are activated, so that the thin film with relatively high electroluminescent brightness is prepared.

Description

Technical Field

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

[0002] Quantum dots refer to semiconductor nanocrystals with a particle size smaller than the Bohr radius of their material. The particle size is generally between 1 and 10 nm. Since electrons and holes are quantum confined, the continuous energy band structure becomes a discrete energy level structure with molecular characteristics, and can emit fluorescence after being excited. Therefore, quantum dots of different sizes can be excited simultaneously with a single wavelength light source. Changing the particle size of quantum dots can adjust its emission wavelength and Stokes shift, and the fluorescence spectrum is narrow and symmetrical, so that quantum dots with various fluorescence spectral characteristics can be prepared.

[0003] Quantum dots have the advantages of adjustable emission spectrum with particle size and composition, high fluorescence quantum yield, narrow emission spectrum, wide excitation spectrum, and good optical stability, which makes the film have excellent application prospects in many fields such as field effect transistors, light-emitting diodes, photoresistors, solar cells, biological characterization, and photoelectric sensors.

[0004] However, the electroluminescent brightness of existing films is relatively low and needs to be further improved. Summary of the invention

[0005] In view of this, the present application provides a method for preparing a thin film, aiming to improve the problem of low electroluminescent brightness of the existing thin film.

[0006] The embodiment of the present application is implemented as follows: a method for preparing a thin film comprises the following steps:

[0007] Provide quantum solution and form a film layer through film forming process;

[0008] The film layer is subjected to plasma treatment by using plasma to obtain a thin film, wherein the plasma includes water plasma.

[0009] Optionally, in some embodiments, the flow rate of the plasma is 50 to 2000 L / h; and / or

[0010] The plasma treatment time is 2 to 30 minutes.

[0011] Optionally, in some embodiments, the plasma also includes oxygen plasma.

[0012] Optionally, in some embodiments, the molar ratio of O radicals to OH radicals in the plasma is greater than 1:1 and less than or equal to 10:1.

[0013] Optionally, in some embodiments, the plasma further comprises one or more of salt plasma and acid plasma.

[0014] Optionally, in some embodiments, the salt plasma includes one or more of halide plasma, sulfide plasma, sulfate plasma, nitrate plasma, carbonate plasma, and acetate plasma; and / or

[0015] The acid plasma includes one or more of hydrogen halide plasma, acetic acid plasma, nitric acid plasma, and sulfuric acid plasma.

[0016] Optionally, in some embodiments, the carrier gas of the plasma is an inert gas.

[0017] Optionally, in some embodiments, the method for preparing the plasma includes: using a plasma generating device to plasma-treat a plasma source to obtain plasma, wherein the plasma source includes a water-containing inert gas, and the water-containing inert gas includes water vapor and an inert gas.

[0018] Optionally, in some embodiments, the relative humidity of the water-containing inert gas is 20% to 80%; and / or

[0019] The inert gas includes one or more of nitrogen, helium, argon, neon and xenon.

[0020] Optionally, in some embodiments, the plasma source also includes oxygen or air.

[0021] Optionally, in some embodiments, the volume concentration of oxygen or air in the plasma source is 20% to 70%; and / or

[0022] The relative humidity of the water-containing inert gas is 10% to 50%.

[0023] Optionally, in some embodiments, the plasma source further includes one or more of a metal salt and an acid.

[0024] Optionally, in some embodiments, the acid includes one or more of hydrogen halide, acetic acid, nitric acid, and sulfuric acid; and / or

[0025] The metal salt includes one or more of halogen salts, sulfonates, sulfates, nitrates, carbonates, and acetates; and / or

[0026] The molar ratio of the salt to the water vapor is (0.001-1):55.6; and / or

[0027] The molar ratio of the acid to the water vapor is (0.001-1):55.6.

[0028] Optionally, in some embodiments, after forming the film layer, the process further comprises: drying the film layer, wherein the drying temperature is 60 to 100° C. and the drying time is 2 to 60 minutes.

[0029] Optionally, in some embodiments, the quantum dots include one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials, wherein the material of the single structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots can respectively include one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds, and the II-VI group compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, Z One or more of CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound includes SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe ... bSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, the III-V group compound includes 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, Ga One or more of AlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, the I-III-VI group compound comprises one or more of CuInS2, CuInSe2 and AgInS2, the perovskite semiconductor material comprises a doped or undoped inorganic perovskite semiconductor, or an organic-inorganic hybrid perovskite semiconductor, the inorganic perovskite semiconductor has a general structural formula of AMX3, wherein A is Cs + ions, M is a divalent metal cation, including Pb 2 + Sn2+ , Cu 2+ 、Ni 2+ 、Cd 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, X is a halogen anion, including Cl - Br - ,I - One or more of the organic-inorganic hybrid perovskite semiconductor has a general structural formula of BMX3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including 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, X is a halogen anion, including Cl - Br - ,I - One or more of; and / or

[0030] The surface of the quantum dot is connected to a ligand with a main chain atom number greater than or equal to 6, and the ligand with a main chain atom number greater than or equal to 6 includes at least one of an acid ligand, a thiol ligand, an amine ligand, a (oxygen) phosphine ligand, a phospholipid, a soft phosphine, polyvinyl pyridine, etc. The acid ligand includes at least one of decadecanoic acid, undecenoic acid, tetradecanoic acid, oleic acid, and stearic acid; the thiol ligand includes at least one of octadecyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan; the amine ligand includes at least one of oleylamine, octadecylamine, and octaamine; the (oxygen) phosphine ligand includes at least one of trioctylphosphine and trioctylphosphine oxide.

[0031] Correspondingly, an embodiment of the present application also provides a film, which is prepared by the above preparation method.

[0032] Correspondingly, an embodiment of the present application further provides a light-emitting device, comprising a stacked anode, a light-emitting layer and a cathode, wherein the light-emitting layer is prepared by the above-mentioned preparation method.

[0033] Optionally, in some embodiments, the anode and the cathode independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode or an alloy electrode, the material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide, the composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS or ZnS / Al / ZnS, and the material of the metal element electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba; and / or

[0034] The light-emitting device further comprises a hole transport layer between the anode and the light-emitting layer, wherein the material of the hole transport layer comprises 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 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, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), 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'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4- 4'-diamine, spiro NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-)phenylene vinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines , 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped P-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or

[0035] The light-emitting device further comprises a hole injection layer between the anode and the light-emitting layer, wherein the material of the hole injection layer comprises one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide and copper oxide; and / or

[0036] The light-emitting device further comprises an electron transport layer between the cathode and the light-emitting layer, wherein the material of the electron transport layer comprises one or more of an inorganic electron transport material and an organic electron transport material, wherein the inorganic electron transport material comprises one or more of a metal oxide, a doped metal oxide, a IIB-VIA semiconductor material, a IIIA-VA semiconductor material and an IB-IIIA-VIA semiconductor material, wherein the metal oxide comprises one or more of ZnO, TiO2, SnO2, ZrO2 and Ta2O5; wherein the metal oxide in the doped metal oxide comprises ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O 3, the dopant in the doped metal oxide includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, and Sn; the IIB-VIA semiconductor material includes one or more of ZnS, ZnSe, and CdS; the IIIA-VA semiconductor material includes one or more of InP and GaP; the IB-IIIA-VIA semiconductor material includes one or more of CuInS and CuGaS; the organic electron transport material includes one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene compounds, and hydroxyquinoline compounds.

[0037] Correspondingly, an embodiment of the present application further provides a display device, comprising the above-mentioned light-emitting device.

[0038] The method for preparing the thin film described in the present application uses water plasma to perform plasma treatment on the film layer. The water is rich in highly active OH radicals and O radicals. The OH radicals and O radicals can fully oxidize and detach the long-chain ligands on the surface of the quantum dots, thereby removing the long-chain ligands on the surface of the quantum dots. Furthermore, when the long-chain ligands on the surface of the quantum dots are removed, the defects on the surface of the quantum dots will increase, and the OH radicals and O radicals can passivate these surface defects and activate the quantum dots, thereby preparing a thin film with higher electroluminescent brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 is a flow chart of a quantum dot purification method provided in an embodiment of the present application;

[0041] Figure 2 is a schematic structural diagram of a light-emitting device provided in an embodiment of the present application;

[0042] Figure 3 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present application;

[0043] Figure 4 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0044] Figure 5 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0045] Figure 6 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0046] Figure 7 is a current density-voltage curve diagram of the light-emitting devices of Examples 1 to 3 of the present application and Comparative Example 1;

[0047] Figure 8 is a current density-voltage curve diagram of the light-emitting devices of Example 18 and Comparative Example 2 of the present application;

[0048] Fig. 9 is a current density-voltage curve diagram of the light-emitting devices of Example 19 and Comparative Example 3 of the present application;

[0049] Fig.10 is a current efficiency-brightness curve diagram of the light-emitting devices of Examples 1 to 3 of the present application and Comparative Example 1;

[0050] Fig.11 is a current efficiency-brightness curve diagram of the light-emitting devices of Example 18 and Comparative Example 2 of the present application;

[0051] Fig.12 It is a current efficiency-brightness curve diagram of the light-emitting devices of Example 19 and Comparative Example 3 of the present application.

[0052] Reference numerals

[0053] Light-emitting device 100 ; anode 10 ; light-emitting layer 20 ; cathode 30 ; hole transport layer 40 ; electron transport layer 50 ; hole injection layer 60 . DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0055] In this application, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order.

[0056] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0057] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0058] In the present application, when a layer is formed "on" another layer, the so-called "on" is a broad concept, which may indicate that the formed another layer is adjacent to the certain layer, or may indicate that there are other spacing structural layers between the another layer and the certain layer. For example, when a second electrode is formed "on" the first carrier functional layer, the so-called "on" may indicate that the formed second electrode is adjacent to the first carrier functional layer, or may indicate that there are other spacing structural layers between the second electrode and the first carrier functional layer, such as a light-emitting layer.

[0059] Various embodiments of the present application may be presented 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 understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0060] Quantum dots (QDs) are only a few to tens of nanometers in size, so long-chain ligands are required to ensure the monodispersity of QDs, both during the synthesis process and to form the final QDs. Long-chain ligands can also passivate imperfect lattice defects on the QD surface and passivate dangling bonds on the QD surface, making QDs have higher fluorescence efficiency. When QDs are used as photoluminescent materials, long-chain ligands significantly improve the stability and luminous efficiency of the film layer. However, when QDs are used as electroluminescent materials for electroluminescence, long-chain ligands usually have poor conductivity. Therefore, some researchers have exchanged ligands on QDs after film formation, replacing long-chain ligands with short-chain ligands, reducing the QD spacing, reducing the carrier transmission distance, and improving the carrier transmission rate and injection capacity. However, on the one hand, such ligand exchange usually uses solvent to elute the solid QD film layer, which will cause the QD film layer to be washed by the solvent, affecting the surface uniformity of the QD film layer, increasing the surface roughness of the QD film layer, and affecting the device performance; on the other hand, due to the wettability problem, it is difficult for the solvent to completely elute the long-chain ligands inside the QD film layer, which makes the ligand exchange incomplete and affects the improvement of QD performance.

[0061] The technical solution of this application is as follows:

[0062] See also Figure 1 The present invention provides a method for preparing a thin film, comprising the following steps:

[0063] Step S11, providing a quantum solution, and forming a film layer through a film forming process;

[0064] Step S12, performing plasma treatment on the film layer to obtain a thin film, wherein the plasma includes water plasma.

[0065] The quantum dot solution includes a solvent and quantum dots dispersed in the solvent, and the surface of the quantum dots is connected with a long-chain ligand, which is a ligand known to exist on the surface of the quantum dots.

[0066] In some embodiments, the number of main chain atoms of the long-chain ligand is greater than or equal to 6.

[0067] In some embodiments, the long-chain ligand includes but is not limited to at least one of an acid ligand, a thiol ligand, an amine ligand, a (oxygen) phosphine ligand, a phospholipid, a soft phosphine, a polyvinyl pyridine, etc. As an example, the acid ligand includes but is not limited to at least one of decadecanoic acid, undecylenic acid, tetradecanoic acid, oleic acid, and stearic acid; the thiol ligand includes but is not limited to at least one of octadecyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan; the amine ligand includes but is not limited to at least one of oleylamine, octadecylamine, and octadecylamine; the (oxygen) phosphine ligand includes but is not limited to at least one of trioctylphosphine and trioctylphosphine oxide.

[0068] It should be noted that due to the presence of quantum dot surface ligands in the film layer and the inherent morphology of the quantum dot particles, there are gaps between the quantum dots in the film layer. Therefore, when the film layer is subjected to plasma treatment, the plasma can enter the film layer and react with the quantum dots in the film layer.

[0069] Water plasma is rich in highly active OH radicals (·OH) and O radicals (O·), which can fully oxidize and detach the long-chain ligands on the surface of quantum dots, thereby removing the long-chain ligands on the surface of quantum dots. Furthermore, when the long-chain ligands on the surface of quantum dots are removed, the defects on the surface of quantum dots will increase, and the OH radicals and O radicals can passivate these surface defects and activate the quantum dots, thereby preparing a film with higher electroluminescent brightness.

[0070] The flow rate of the plasma is 50 to 2000 L / h, for example, 100 L / h, 200 L / h, 300 L / h, 400 L / h, 500 L / h, 600 L / h, 700 L / h, 800 L / h, 900 L / h, 1000 L / h, 1100 L / h, 1200 L / h, 1300 L / h, 1400 L / h, 1500 L / h, 1600 L / h, 1700 L / h, 1800 L / h, 1900 L / h, etc., and the treatment time is 2 to 30 min, for example, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0071] In some embodiments, the plasma further includes oxygen plasma, in other words, the plasma includes water plasma and oxygen plasma. Thus, adding oxygen plasma to the plasma can increase the proportion of O radicals in the plasma, and when the film layer is subjected to plasma treatment, the long-chain ligands on the surface of the quantum dots can be more effectively oxidized and detached, thereby more effectively removing the long-chain ligands on the surface of the quantum dots.

[0072] In at least some embodiments, in the plasma, the molar ratio of O radicals to OH radicals is greater than 1:1 and less than or equal to 10:1, for example, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc. Within the ratio range, the long-chain ligands on the surface of the quantum dots can be effectively oxidized and detached more effectively, thereby more effectively removing the long-chain ligands on the surface of the quantum dots.

[0073] In some embodiments, the plasma further comprises one or more of salt plasma and acid plasma. The active groups (free radicals) in the salt plasma and the acid plasma can further passivate the defects on the surface of the quantum dots, thereby improving the stability of the quantum dots.

[0074] It can be understood that the salt plasma described in the present application refers to plasma formed by salts, and the acid plasma described in the present application refers to plasma formed by acids.

[0075] The salt plasma includes, but is not limited to, one or more of halide plasma, sulfur salt (metal sulfide) plasma, sulfate plasma, nitrate plasma, carbonate plasma, and acetate plasma.

[0076] Wherein, the halide plasma includes but is not limited to one or more of sodium halide plasma, potassium halide plasma, lithium halide plasma, and zinc halide plasma; the sulfide plasma includes but is not limited to one or more of sodium sulfide plasma, potassium sulfide plasma, lithium sulfide plasma, and zinc sulfide plasma; the nitrate plasma includes but is not limited to one or more of sodium nitrate plasma, potassium nitrate plasma, lithium nitrate plasma, and zinc nitrate plasma; the carbonate plasma includes but is not limited to one or more of sodium carbonate plasma, potassium carbonate plasma, lithium carbonate plasma, and zinc carbonate plasma; the acetate plasma includes but is not limited to one or more of sodium acetate plasma, potassium acetate plasma, lithium acetate plasma, and zinc acetate plasma.

[0077] The acid plasma includes, but is not limited to, one or more of hydrogen halide plasma, acetic acid plasma, nitric acid plasma, and sulfuric acid plasma.

[0078] The hydrogen halide plasma includes but is not limited to one or more of hydrogen chloride plasma, hydrogen bromide plasma, hydrogen fluoride plasma, and hydrogen iodide plasma.

[0079] The halogen salt plasma and the hydrogen halide plasma contain halogen free radicals, such as F free radicals, Cl free radicals, Br free radicals, I free radicals, etc., the sulfide salt plasma contains S2-free radicals, the sulfate plasma and the sulfuric acid plasma contain SO2-free radicals, the nitrate plasma and the nitric acid plasma contain NO-free radicals, the carbonate plasma contains CO2-free radicals, and the acetate plasma and the acetic acid plasma contain CHCOO-free radicals. The free radicals can further passivate the defects on the surface of the quantum dots, thereby improving the stability of the quantum dots.

[0080] In some embodiments, the carrier gas of the plasma is an inert gas.

[0081] The plasma is prepared by a known method. In some embodiments, the method for preparing the plasma includes: using a plasma generator to perform plasma treatment on a plasma source.

[0082] The plasma source includes a water-containing inert gas, which includes water vapor and an inert gas, and it is understandable that the inert gas is a carrier of the water vapor.

[0083] In some embodiments, the relative humidity of the water-containing inert gas is 20% to 80%, for example, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc.

[0084] The inert gas may include, but is not limited to, one or more of nitrogen, helium, argon, neon, and xenon.

[0085] The method for treating the water-containing inert gas by the plasma generating device includes but is not limited to one or more of dielectric barrier discharge, microwave discharge, glow discharge, and corona discharge.

[0086] In some embodiments, the plasma source further includes oxygen or air. The oxygen and air can generate oxygen plasma in a plasma generator, so that the content of O free radicals in the generated plasma can be increased, thereby improving the effect of fully oxidizing and detaching the long-chain ligands on the surface of the quantum dots. In addition, the addition of oxygen or air can also reduce the amount of inert gas used, thereby reducing costs.

[0087] In the plasma source, the volume concentration of the oxygen or air is 20% to 70%. It is understood that the addition of oxygen or air will reduce the relative humidity of the water-containing inert gas. At this time, the relative humidity of the water-containing inert gas is 10% to 50%.

[0088] In some embodiments, the plasma source further comprises one or more of a metal salt and an acid. The metal salt and the acid can generate corresponding salt plasma and acid plasma in a plasma generating device.

[0089] The acid includes, but is not limited to, one or more of hydrogen halide, acetic acid, nitric acid, and sulfuric acid. The hydrogen halide includes, but is not limited to, one or more of hydrogen chloride, hydrogen bromide, hydrogen fluoride, and hydrogen iodide.

[0090] The metal salt may include, but is not limited to, one or more of halogen salts, sulfonates (metal sulfides), sulfates, nitrates, carbonates, and acetates. The halogen salts include, but are not limited to, one or more of sodium halides, potassium halides, lithium halides, and zinc halides; the sulfonates include, but are not limited to, one or more of sodium sulfide, potassium sulfide, lithium sulfide, and zinc sulfide; the nitrates include, but are not limited to, one or more of sodium nitrate, potassium nitrate, lithium nitrate, and zinc nitrate; the carbonates include, but are not limited to, one or more of sodium carbonate, potassium carbonate, lithium carbonate, and zinc carbonate; and the acetates include, but are not limited to, one or more of sodium acetate, potassium acetate, lithium acetate, and zinc acetate.

[0091] It is understood that the metal salt and the acid in the plasma source are in gaseous state.

[0092] When the plasma source further includes salts, the molar ratio of the salts to the water vapor is (0.001-1):55.6, for example, 0.001:55.6, 0.008:55.6, 0.01:55.6, 0.015:55.6, 0.016:55.6, 0.018:55.6, 0.02:55.6, 0.03:55.6, 0.04:55.6, 0.05:55.6, 0.06:55.6, 0.07:55.6, 0.08:55.6, 0.1:55.6, 0.12:55.6, 0.14:55.6, 0.15:55.6, 0.18:55.6, 0.2:55.6, 0.25:55.6, 0.3:55.6, 0.35:55.6, 0.4:55.6, 0.45:55.6, 0.5:55.6, 0.55:55.6, 0.6:55.6, 0.65:55.6, 0.7:55.6, 0.75:55.6, 0.8:55.6, 0.85:55.6, 0.9:55.6, 0.95:55.6, etc.

[0093] When the plasma source further includes an acid, the molar ratio of the acid to the water vapor is (0.001-1):55.6, for example, 0.001:55.6, 0.008:55.6, 0.01:55.6, 0.015:55.6, 0.016:55.6, 0.018:55.6, 0.02:55.6, 0.03:55.6, 0.04:55.6, 0.05:55.6, 0.06:55.6, 0.07:55.6, 0.08:55.6, 0.1:55.6, 0. .12:55.6、0.14:55.6、0.15:55.6、0.18:55.6、0.2:55.6、0.25:55.6、0.3:55.6、0.35:55.6、0.4:55.6、0.45:55.6、0.5:55.6、0.55:55.6、0.6:55.6、0.65:55.6、0.7:55.6、0.75:55.6、0.8:55.6、0.85:55.6、0.9:55.6、0.95:55.6, etc.

[0094] In some embodiments, in step S11, after forming the film layer, the step further includes: drying the film layer.

[0095] It can be understood that the drying can be any one of vacuum drying, reduced pressure drying, freeze drying and heating drying.

[0096] In at least one embodiment, the drying is heat drying, and the temperature of the heat drying is 60 to 100° C. and the time is 2 to 60 minutes.

[0097] The quantum dots may include, but are not limited to, one or more of single structure quantum dots, core-shell structure quantum dots, and perovskite type semiconductor materials.

[0098] The material of the single structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots may respectively include but are not limited to one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds. The II-VI group compounds may include, 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 include, 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 III-V group compound may include, but is 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 I-III-VI group compound may include, but is not limited to, one or more of CuInS2, CuInSe2, and AgInS2.

[0099] It is understandable that the core material and the shell material of the core-shell structured quantum dot may be the same or different. In at least one embodiment, the core material and the shell material of the core-shell structured quantum dot are different.

[0100] As an example, the core-shell structured quantum dots may include but are not limited to one or more of CdSe / ZnSe, CdTe / ZnSe, CdZnSe / ZnSe, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / ZnS, CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnSe / ZnSCdZnTe / ZnSe, CdSe / CdZnSe / ZnSe, CdSe / CdZnSeS / ZnS, CdTe / CdZnTe / ZnSe, CdTe / CdZnSe / ZnSe and InP / ZnSe / ZnS.

[0101] The perovskite semiconductor material may include but is not limited to doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors. The inorganic perovskite semiconductor has a general structural formula of AMX3, wherein A is Cs + ions, M is a divalent metal cation, including 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, X is a halogen anion, including Cl - Br - ,I - The general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including 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, X is a halogen anion, including Cl - Br - ,I - One or more of .

[0102] The solvent is a solvent known in the art for preparing or dispersing quantum dots, and may include one or more of a coordinating solvent and a non-coordinating solvent. The coordinating solvent may include, but is not limited to, one or more of saturated or unsaturated fatty acids having a carbon number greater than or equal to 5, and saturated or unsaturated amines having a carbon number greater than or equal to 6, and the non-coordinating solvent may include, but is not limited to, one or more of alkane compounds having a carbon number greater than or equal to 10, olefin compounds having a carbon number greater than or equal to 10, ether compounds having a carbon number greater than or equal to 10, and aromatic compounds having a carbon number greater than or equal to 10. As an example, the first solvent may include, but is not limited to, one or more of n-hexane, n-octane, toluene, tetradecene, hexadecene, octadecene, eicosene, and paraffin oil.

[0103] It is understood that the concentration of the quantum dot solution to be purified is not limited, and any concentration of quantum dot solution can be purified by the purification method of the present application. In at least some embodiments, the mass concentration of quantum dots in the quantum dot solution to be purified is 30 to 50 mg / mL, for example, 32 to 40 mg / mL, 34 to 42 mg / mL, 36 to 44 mg / mL, 38 to 46 mg / mL, 39 to 48 mg / mL, etc.

[0104] In a second aspect, an embodiment of the present application further provides a film prepared by the preparation method described above.

[0105] The surfaces of the quantum dots in the film are connected with OH radicals and O radicals.

[0106] In some implementations, the surface of the quantum dots in the film is connected to one or more of halogen radicals, S2-radicals, SO2-radicals, NO-radicals, CO2-radicals, and CHCOO-radicals.

[0107] Third, see Figure 2 The embodiment of the present application further provides a light emitting device 100, comprising an anode 10, a light emitting layer 20 and a cathode 30 stacked in sequence. The light emitting layer 20 is the thin film described above.

[0108] See also Figure 3 In some embodiments, the light emitting device 100 further includes a hole transport layer 40 between the anode 10 and the light emitting layer 20. In other words, the light emitting device 100 includes the anode 10, the hole transport layer 40, the light emitting layer 20 and the cathode 30 stacked in sequence.

[0109] See also Figure 4 In some embodiments, the light emitting device 100 further includes an electron transport layer 50 between the light emitting layer 20 and the cathode 30. In other words, the light emitting device 100 includes an anode 10, a light emitting layer 20, an electron transport layer 50 and a cathode 30 stacked in sequence.

[0110] See also Figure 5 In some embodiments, the light-emitting device 100 includes an anode 10, a hole transport layer 40, a light-emitting layer 20, an electron transport layer 50 and a cathode 30 stacked in sequence.

[0111] See also Figure 6 In some embodiments, the light emitting device 100 further includes a hole injection layer 60 located between the anode 10 and the hole transport layer 40 .

[0112] The anode 10 and the cathode 30 are anodes and cathodes for light-emitting devices known in the art, and can be independently, but not limited to, doped metal oxide particle electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, metal single-substance electrodes or alloy electrodes. The material of the doped metal oxide particle electrode can be, but not limited to, one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO) and aluminum-doped magnesium oxide (AMO). The composite electrode is a composite electrode in which metal is sandwiched between doped or undoped transparent metal oxide particles, such as AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, etc., wherein " / " represents a stacked structure, for example, AZO / Ag / AZO represents a composite electrode including an AZO layer, an Ag layer and an AZO layer stacked in sequence. The material of the metal single substance electrode may include but is not limited to one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba.

[0113] The material of the hole transport layer 40 may also be a material known in the art for a hole transport layer, for example, it may include but is not limited to 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine (α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), N ...1-naphthyl)-1,1'-biphenyl-4,4"-diamine (α-NPD), (3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4'-tri(N-carbazolyl)-triphenylamine (TCTA), 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl -1,1'-biphenyl-4-4'-diamine (NPB), spiro NPB, poly(phenylene vinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MOMO-PPV), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-omeTAD), 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), 1,3-bis(carbazol-9-yl)benzene (MCP ), polyaniline, polypyrrole, poly(p-)phenylene vinylene, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped P-type gallium nitride, doped or undoped CrO3, doped or undoped CuO. One or more.

[0114] The material of the electron transport layer 50 is a material known in the art for electron transport layers, for example, it may include but is not limited to one or more of inorganic electron transport materials and organic electron transport materials. The inorganic electron transport material includes one or more of metal oxides, doped metal oxides, IIB-VIA semiconductor materials, IIIA-VA semiconductor materials and IB-IIIA-VIA semiconductor materials, the metal oxide includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5; the metal oxide in the doped metal oxide includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3, and the dopant in the doped metal oxide includes Al, Mg, Li , Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Sn one or more; the IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, CdS; 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; the organic electron transport material includes one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene compounds, hydroxyquinoline compounds.

[0115] The material of the hole injection layer 60 can be a material known in the art for a hole injection layer, for example, it can be selected from but not limited to one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3 (PEDOT:PSS:s-MoO3), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), tetracyanoquinodimethane (F4-TCQN), copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide and copper oxide.

[0116] It is understandable that the light emitting device 100 may also be further provided with some functional layers conventionally used in light emitting devices to help improve the performance of the light emitting device, such as an electron blocking layer, a hole blocking layer, an electron injection layer, an interface modification layer, etc.

[0117] It can be understood that the materials of each layer of the light-emitting device 100 can be adjusted according to the light-emitting requirements of the light-emitting device 100 .

[0118] In some embodiments, the light emitting device 100 further includes a substrate, and the substrate is disposed on a side of the anode 10 away from the light emitting layer 20 , or the substrate is disposed on a side of the cathode 30 away from the light emitting layer 20 .

[0119] The substrate may be a rigid substrate or a flexible substrate. In some embodiments, the material of the substrate may include but is not limited to one or more of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide and polyether sulfone.

[0120] It can be understood that the light emitting device 100 can be an upright light emitting device or an inverted light emitting device. The light emitting device 100 can be a quantum dot light emitting device or an organic light emitting device.

[0121] The light-emitting layer 20 of the light-emitting device 100 includes quantum dots purified by the purification method described in the present application, and thus has higher light-emitting efficiency and longer lifespan.

[0122] In a fourth aspect, an embodiment of the present application further provides a display device, which includes the light-emitting device 100 .

[0123] The display device can be any electronic product with a display function, including but not limited to smart phones, tablet computers, laptops, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, car displays, televisions or e-book readers, among which smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0124] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0125] Example 1

[0126] Providing an ITO substrate, ultrasonically cleaning the ITO substrate with acetone and ethanol for 15 minutes, then cleaning with deionized water and then drying with air, then drying on a hot plate at 150° C. for 10 minutes, and then irradiating with ultraviolet light for 20 minutes to increase the work function of ITO;

[0127] A cleaned ITO substrate was spin-coated with a PEDOT:PSS material having a mass fraction of 2.8% at a speed of 3000 rpm for 30 seconds, and then heated on a hot plate at 150°C for 20 minutes to obtain a hole injection layer with a thickness of 20 nm.

[0128] In an inert atmosphere, a TFB material with a concentration of 8 mg / mL was spin-coated on the hole injection layer at a rotation speed of 3000 rpm for 30 seconds, and then heated on a heating plate at 170° C. for 20 minutes to obtain a hole transport layer with a thickness of 15 nm;

[0129] Spin-coat the CdZnSe / ZnSe / CdZnS / ZnS blue quantum dot material with a concentration of 30 mg / mL on the hole transport layer at a rotation speed of 2000 rpm for 30 seconds, and then heat on a hot plate at 80° C. for 5 minutes to obtain a film layer with a thickness of 40 nm;

[0130] The film layer is placed 5 cm below the plasma nozzle, and the film layer is treated with water plasma under the condition that the ambient pressure is atmospheric pressure, wherein the flow rate of the water plasma is 200 L / h, the treatment time is 10 min, wherein the atmosphere used in the plasma generating device is argon atmosphere, and the relative humidity is 40%, to obtain a thin film, i.e., a light-emitting layer;

[0131] Spin-coat Mg-doped ZnO colloid (Mg mass percentage is 15%) with a concentration of 30 mg / mL on the light-emitting layer at a rotation speed of 4000 rpm for 30 seconds, and then evacuate at a low pressure of 0.001-10 Pa for 5-20 minutes to obtain an electron transport layer with a thickness of 40 nm;

[0132] Ag is evaporated on the electron transport layer, wherein the vacuum degree is not higher than 3x10 -4 Pa, the evaporation rate is 1 Å / s, the time is 1000 s, and the cathode with a thickness of 100 nm is obtained;

[0133] Packaging to obtain a light-emitting device.

[0134] Example 2

[0135] This embodiment is basically the same as Embodiment 1, except that, in the thin film preparation process of this embodiment, the atmosphere used by the plasma generating device also includes oxygen, wherein the volume fraction of oxygen is 50%, and the relative humidity of the argon atmosphere is 20%.

[0136] Example 3

[0137] This embodiment is basically the same as Embodiment 1, except that, in the thin film preparation process of this embodiment, the argon atmosphere is obtained by heating an aqueous solution of NaF in an argon atmosphere containing oxygen, wherein the concentration of NaF in the aqueous solution of NaF is 0.1 mol / L, and the atmosphere used in the plasma generating device of this embodiment includes water, NaF, oxygen, and argon, the volume fraction of oxygen is 50%, and the relative humidity of the argon atmosphere is 20%.

[0138] Example 4

[0139] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the flow rate of the water plasma is 50 L / h.

[0140] Example 5

[0141] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the flow rate of the water plasma is 2000 L / h.

[0142] Example 6

[0143] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the treatment time of water plasma is 2 minutes.

[0144] Example 7

[0145] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the treatment time of water plasma is 30 minutes.

[0146] Example 8

[0147] This embodiment is substantially the same as Embodiment 2, except that, in this embodiment, the volume concentration of oxygen is 20%.

[0148] Example 9

[0149] This embodiment is substantially the same as Embodiment 2, except that, in this embodiment, the volume concentration of oxygen is 70%.

[0150] Example 10

[0151] This embodiment is substantially the same as Embodiment 2, except that, in this embodiment, the relative humidity of the argon atmosphere is 10%.

[0152] Embodiment 11

[0153] This embodiment is substantially the same as Embodiment 2, except that, in this embodiment, the relative humidity of the argon atmosphere is 50%.

[0154] Example 12

[0155] This embodiment is substantially the same as embodiment 3, except that, in this embodiment, the concentration of NaF is 0.001 mol / L.

[0156] Embodiment 13

[0157] This embodiment is substantially the same as Embodiment 3, except that, in this embodiment, the concentration of NaF is 1 mol / L.

[0158] Embodiment 14

[0159] This embodiment is substantially the same as Embodiment 3, except that, in this embodiment, sodium acetate is used to replace NaF in Embodiment 3.

[0160] Embodiment 15

[0161] This embodiment is substantially the same as embodiment 3, except that, in this embodiment, sodium nitrate is used to replace NaF in embodiment 3.

[0162] Example 16

[0163] This embodiment is substantially the same as Embodiment 3, except that, in this embodiment, sodium sulfate is used to replace NaF in Embodiment 3.

[0164] Embodiment 17

[0165] This embodiment is substantially the same as Embodiment 3, except that, in this embodiment, sodium carbonate is used to replace NaF in Embodiment 3.

[0166] Embodiment 18

[0167] This embodiment is basically the same as Embodiment 3, except that, in this embodiment, CdZnSe / ZnSe / CdZnS / ZnS red quantum dots are used to replace the CdZnSe / ZnSe / CdZnS / ZnS blue quantum dots in Embodiment 1.

[0168] Embodiment 19

[0169] This embodiment is basically the same as Embodiment 3, except that, in this embodiment, CdZnSe / ZnSe / CdZnS / ZnS green quantum dots are used to replace the CdZnSe / ZnSe / CdZnS / ZnS blue quantum dots in Embodiment 1.

[0170] Comparative Example 1

[0171] This comparative example is basically the same as Example 1, except that in this comparative example, the film layer is not subjected to water plasma treatment, and the prepared film layer is the light-emitting layer.

[0172] Comparative Example 2

[0173] This comparative example is basically the same as Example 18, except that in this comparative example, the film layer is not subjected to water plasma treatment, and the prepared film layer is the light-emitting layer.

[0174] Comparative Example 3

[0175] This comparative example is basically the same as Example 19, except that in this comparative example, the film layer is not subjected to water plasma treatment, and the prepared film layer is the light-emitting layer.

[0176] The light emitting devices of device embodiments 1 to 3, 18, 19 and device comparative examples 1 to 3 were heated on a 120° C. heating plate for 20 min, and then subjected to JVL data testing, and the results were respectively Figures 7 to 9 The current density-voltage curve shown in Figures 10-12 The current efficiency-brightness curve is shown.

[0177] Depend on Figure 7 It can be seen that under the same voltage, the current density of the light-emitting devices of Examples 1 to 3 is higher than the current density of the light-emitting device of Comparative Example 1; Figure 8 It can be seen that under the same voltage, the current density of the light-emitting device of Example 18 is higher than the current density of the light-emitting device of Comparative Example 2; Fig. 9 It can be seen that, under the same voltage, the current density of the light-emitting device of Example 19 is higher than that of the light-emitting device of Comparative Example 3. It can be seen that the light-emitting device prepared by the preparation method of the present application can have a higher current density.

[0178] Depend on Fig.10 It can be seen that under the same current efficiency, the external quantum efficiency of the light-emitting devices of Examples 1 to 3 is higher than the external quantum efficiency of the light-emitting device of Comparative Example 1; Fig.11 It can be seen that under the same current efficiency, the external quantum efficiency of the light-emitting device of Example 18 is higher than the external quantum efficiency of the light-emitting device of Comparative Example 2; Fig.12 It can be seen that, at the same current efficiency, the external quantum efficiency of the light-emitting devices of Examples 1 to 3 is higher than that of the light-emitting device of Comparative Example 3. It can be seen that the light-emitting device prepared by the preparation method of the present application can have a higher luminous efficiency.

[0179] The light emitting devices of device examples 1 to 19 and device comparative examples 1 to 3 were heated on a heating plate at 120° C. for 20 min, and then the maximum brightness L max Test, life T95 test, life T95@1000nit test, the results are shown in Table 1.

[0180] Among them, the JVL test method is: measured by LabView controlling the efficiency test system built by QE PRO spectrometer, Keithley 2400, and Keithley6485, with a driving voltage of 0-8V and a step size of 0.1V, and drawing the current density-voltage curve and the current efficiency-brightness curve;

[0181] Maximum brightness L maxThe test method is: using FSD FPD optical characteristic measurement equipment, controlling the efficiency test system built by QE PRO spectrometer, Keithley 2400, and Keithley 6485 through LabView, measuring parameters such as voltage, current, brightness, and luminous spectrum, and recording the maximum brightness L max ;

[0182] The test method for life span T95 and life span T95@1000nit is: in CDA gas, under constant current drive, measure the time taken for the device brightness to decay to a certain proportion of the maximum brightness, and the time taken for the brightness to decay to 95% of the maximum brightness is defined as T95, and the life span is the measured life span. In order to shorten the life span test cycle, the device life span test is usually carried out at high brightness by accelerating device aging, and the life span at low brightness is obtained by fitting the decay fitting formula. For example, the life span at 1000nits is recorded as T95@1000nits, and the calculation formula is:

[0183]

[0184] Among them, T95 L The lifespan under low brightness, generally 1000nits, T95 H is the lifespan under high brightness, that is, the measured lifespan, L H is the maximum brightness that the device is accelerated to, L L Generally, it is 1000nits, A is the acceleration factor, which is 1.7. The constant current is 2mA.

[0185] Table 1:

[0186] <![CDATA[L max (cd / m 2 )]]> T95(h) T95@1000nits(h) Example 1 5789 2.17 42.95 Example 2 7129 2.23 62.87 Example 3 8155 2.54 90.16 Example 4 4600 2.46 32.88 Example 5 5519 1.9 34.63 Example 6 4712 2.31 32.24 Example 7 4567 1.56 20.63 Example 8 6950 2.12 57.32 Example 9 6814 2.14 55.79 Example 10 6412 2.3 54.17 Embodiment 11 7276 1.6 46.57 Example 12 7937 2.944 80.85 Embodiment 13 8639 2.12 82.81 Embodiment 14 8322 2.07 75.91 Embodiment 15 8753 2.29 91.43 Example 16 9080 2.29 97.58 Embodiment 17 8596 2.06 79.93 Embodiment 18 16950 76.01 7038.58 Embodiment 19 74583 13.68 13561.56 Comparative Example 1 3712 1.48 13.77 Comparative Example 2 9546 45.57 1684.19 Comparative Example 3 45841 8.54 3885.65

[0187] From Table 1 we can see that:

[0188] Compared with the blue light emitting device of comparative example 1, the blue light emitting devices of embodiments 1 to 17 have higher maximum brightness and longer life. It can be seen that the light emitting device prepared by the preparation method described in the present application can effectively improve the maximum brightness and life of the light emitting device. The reason may be that the light emitting layer of the light emitting device of embodiments 1 to 17 is prepared by the thin film preparation method described in the present application, which can effectively improve the luminous efficiency and stability of the thin film.

[0189] Compared with the red light emitting device of comparative example 2, the red light emitting device of example 18 has a higher maximum brightness and a longer lifespan. It can be seen that the light emitting device prepared by the preparation method described in the present application can effectively improve the maximum brightness and lifespan of the light emitting device. The reason may be that the light emitting layer of the light emitting device of examples 1 to 17 is prepared by the thin film preparation method described in the present application, which can effectively improve the luminous efficiency and stability of the thin film.

[0190] Compared with the green light-emitting device of comparative example 3, the green light-emitting device of example 19 has a higher maximum brightness and a longer lifespan. It can be seen that the light-emitting device prepared by the preparation method described in the present application can effectively improve the maximum brightness and lifespan of the light-emitting device. The reason may be that the light-emitting layer of the light-emitting device of examples 1 to 17 is prepared by the thin film preparation method described in the present application, which can effectively improve the luminous efficiency and stability of the thin film.

[0191] The technical solutions provided by the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a thin film, characterized in that: The steps include: Provide quantum solution and form a film layer through film forming process; The film layer is subjected to plasma treatment by using plasma to obtain a thin film, wherein the plasma includes water plasma.

2. The preparation method according to claim 1, characterized in that The plasma flow rate is 50 to 2000 L / h; and / or The plasma treatment time is 2 to 30 minutes.

3. The preparation method according to claim 1, characterized in that: The plasma also includes oxygen plasma.

4. The preparation method according to claim 3, characterized in that: The molar ratio of O radicals to OH radicals in the plasma is greater than 1:1 and less than or equal to 10:

1.

5. The preparation method according to claim 1, characterized in that: The plasma further comprises one or more of salt plasma and acid plasma.

6. The preparation method according to claim 5, characterized in that: The salt plasma includes one or more of halide plasma, sulfide plasma, sulfate plasma, nitrate plasma, carbonate plasma, and acetate plasma; and / or The acid plasma includes one or more of hydrogen halide plasma, acetic acid plasma, nitric acid plasma, and sulfuric acid plasma.

7. The preparation method according to claim 1, characterized in that: The carrier gas of the plasma is an inert gas.

8. The preparation method according to claim 1, characterized in that: The plasma preparation method comprises: using a plasma generating device to plasma-treat a plasma source to obtain plasma, wherein the plasma source comprises a water-containing inert gas, and the water-containing inert gas comprises water vapor and an inert gas.

9. The preparation method according to claim 8, characterized in that: The relative humidity of the water-containing inert gas is 20% to 80%; and / or The inert gas includes one or more of nitrogen, helium, argon, neon and xenon.

10. The preparation method according to claim 8, characterized in that: The plasma source also includes oxygen or air.

11. The preparation method according to claim 10, characterized in that: In the plasma source, the volume concentration of oxygen or air is 20% to 70%; and / or The relative humidity of the water-containing inert gas is 10% to 50%.

12. The preparation method according to claim 8, characterized in that: The plasma source also includes one or more of a metal salt and an acid.

13. The preparation method according to claim 12, characterized in that: The acid includes one or more of hydrogen halide, acetic acid, nitric acid, and sulfuric acid; and / or The metal salt includes one or more of halogen salts, sulfonates, sulfates, nitrates, carbonates, and acetates; and / or The molar ratio of the salt to the water vapor is (0.001-1):55.6; and / or The molar ratio of the acid to the water vapor is (0.001-1):55.

6.

14. The preparation method according to claim 1, characterized in that: After the film layer is formed, the method further comprises: drying the film layer, wherein the drying temperature is 60 to 100° C. and the drying time is 2 to 60 minutes.

15. The preparation method according to claim 1, characterized in that: The quantum dots include one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials, wherein the material of the single structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots can respectively include one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds, and the II-VI group compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnS Te, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound includes SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, P bSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, the III-V group compound includes 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, GaAlN As, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, the I-III-VI group compound includes one or more of CuInS2, CuInSe2 and AgInS2, the perovskite semiconductor material includes a doped or undoped inorganic perovskite semiconductor, or an organic-inorganic hybrid perovskite semiconductor, the inorganic perovskite semiconductor has a general structural formula of AMX3, wherein A is Cs + ions, M is a divalent metal cation, including 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, X is a halogen anion, including Cl - Br - ,I - One or more of the organic-inorganic hybrid perovskite semiconductor has a general structural formula of BMX3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including 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, X is a halogen anion, including Cl - Br - ,I - One or more of; and / or The surface of the quantum dot is connected to a ligand with a main chain atom number greater than or equal to 6, and the ligand with a main chain atom number greater than or equal to 6 includes at least one of an acid ligand, a thiol ligand, an amine ligand, a (oxygen) phosphine ligand, a phospholipid, a soft phosphine, polyvinyl pyridine, etc. The acid ligand includes at least one of decadecanoic acid, undecenoic acid, tetradecanoic acid, oleic acid, and stearic acid; the thiol ligand includes at least one of octadecyl mercaptan, dodecyl mercaptan, and octadecyl mercaptan; the amine ligand includes at least one of oleylamine, octadecylamine, and octaamine; the (oxygen) phosphine ligand includes at least one of trioctylphosphine and trioctylphosphine oxide.

16. A film, characterized in that: The film is prepared by the preparation method according to any one of claims 1 to 15.

17. A light emitting device comprising a stacked anode, a light emitting layer and a cathode, characterized in that: The light-emitting layer is prepared by the preparation method according to any one of claims 1 to 15.

18. The light emitting device according to claim 17, characterized in that: The anode and the cathode independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal single substance electrode or an alloy electrode, the material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide, the composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS or ZnS / Al / ZnS, and the material of the metal single substance electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba; and / or The light-emitting device further comprises a hole transport layer between the anode and the light-emitting layer, wherein the material of the hole transport layer comprises 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 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, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), 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'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4- 4'-diamine, spiro NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-)phenylene vinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines , 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped P-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or The light-emitting device further comprises a hole injection layer between the anode and the light-emitting layer, wherein the material of the hole injection layer comprises one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide and copper oxide; and / or The light-emitting device further comprises an electron transport layer between the cathode and the light-emitting layer, wherein the material of the electron transport layer comprises one or more of an inorganic electron transport material and an organic electron transport material, wherein the inorganic electron transport material comprises one or more of a metal oxide, a doped metal oxide, a IIB-VIA semiconductor material, a IIIA-VA semiconductor material and an IB-IIIA-VIA semiconductor material, wherein the metal oxide comprises one or more of ZnO, TiO2, SnO2, ZrO2 and Ta2O5; wherein the metal oxide in the doped metal oxide comprises ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O 3, the dopant in the doped metal oxide includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, and Sn; the IIB-VIA semiconductor material includes one or more of ZnS, ZnSe, and CdS; the IIIA-VA semiconductor material includes one or more of InP and GaP; the IB-IIIA-VIA semiconductor material includes one or more of CuInS and CuGaS; the organic electron transport material includes one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene compounds, and hydroxyquinoline compounds.

19. A display device, characterized in that: A light-emitting device comprising any one of claims 17 to 18.

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