Ink, thin film, and light emitting device

Abstract

The invention discloses ink, a thin film and a light-emitting device. The ink comprises a light-emitting material, a polymer thickening agent and a solvent. The polymer thickening agent is added into the ink disclosed by the invention, and the polymer thickening agent has relatively good capability of inhibiting precipitation and layering, so that the ink has relatively high stability.

Description

Technical Field

[0001] The present application relates to the field of luminescent materials, and in particular to an ink, a film and a luminescent device. Background Art

[0002] The solution method for preparing thin films is widely used in the preparation of thin films, such as the preparation of luminescent thin films, due to its simple process and good film-forming effect.

[0003] The solution method for preparing thin films usually uses ink to prepare thin films, wherein the stability of the ink directly affects its film-forming effect.

[0004] However, the stability of existing inks is poor and needs to be further improved. Summary of the invention

[0005] In view of this, the present application provides an ink, aiming to improve the problem of poor stability of existing inks.

[0006] The embodiment of the present application is implemented as follows: an ink includes a luminescent material, a polymer thickener and a solvent.

[0007] Optionally, in some embodiments, the polymer thickener includes one or more of a cellulose thickener, a polyacrylic thickener, and an associative polyurethane thickener;

[0008] And / or, based on the total mass of the luminescent material and the polymer thickener, the content of the polymer thickener in the total mass is 0.1 wt% to 10 wt%.

[0009] Optionally, in some embodiments, the cellulose thickener includes one or more of methyl cellulose, ethyl cellulose, benzyl cellulose, phenyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, and benzyl cyanoethyl cellulose;

[0010] And / or, the polyacrylic thickener includes one or more of polymethacrylic acid, polymethyl methacrylate, sodium polymethacrylate, and polyacrylate;

[0011] And / or, the associative polyurethane thickener includes one or more of polyether polyurethane, polyester polyurethane, and ethylene oxide polyurethane (HEUR).

[0012] Optionally, in some embodiments, the luminescent material includes one or more of an organic luminescent material and an inorganic luminescent material, and the organic luminescent material includes CBP: Ir(mppy)34,4'-bis(N-carbazole)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine iridium(III), 4,4',4"-tris(carbazole-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine iridium, diaromatic anthracene derivatives, distilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBP e fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescent material, TTA material, thermally activated delayed material, polymer containing BN covalent bond, hybrid localized charge transfer excited state material, exciplex luminescent material, polyacetylene and its derivatives, polyparaphenylene and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives, the anthracene thermal exciton material includes one or more of PABPP, PAC, mPAC, PAIDO, PABP, PATPA;The inorganic luminescent material includes one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials. 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 are independently selected from 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 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, and the general structural formula of the inorganic perovskite semiconductor is AMX3, wherein A is Cs; + ions, M is a divalent metal cation, including Pb 2+ Sn 2+ , Cu 2+ 、Ni2+ 、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 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 .

[0013] Optionally, in some embodiments, the luminescent material is an organic luminescent material, and the concentration of the organic luminescent material in the ink is 5 to 20 mg / mL;

[0014] And / or, the luminescent material is an inorganic luminescent material, and the concentration of the inorganic luminescent material in the ink is 5 to 40 mg / mL;

[0015] and / or, the viscosity of the ink is 1 to 20 cP;

[0016] And / or, the surface tension of the ink is 20-40 mN / m, preferably, the surface tension of the ink is 29-35 mN / m;

[0017] And / or, the solvent includes one or more of chloroform, dichloromethane, formamide, trifluoroacetic acid, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, hexamethylphosphoramide, methanol, acetic acid, ethanol, isopropanol, pyridine, tetramethylethylenediamine, acetone, triethylamine, n-butanol, dioxane, tetrahydrofuran, methyl formate, tributylamine, methyl ethyl ketone, ethyl acetate, chloroform, trioctylamine, dimethyl carbonate, ethyl ether, isopropyl ether, n-butyl ether, trichloroethylene, diphenyl ether, ethylene dichloride, benzene, toluene, carbon tetrachloride, carbon disulfide, cyclohexane, and hexane.

[0018] Accordingly, the embodiment of the present application further provides a thin film, wherein the thin film is prepared from the ink through a film-forming process;

[0019] Alternatively, the material of the film includes a light-emitting material and the polymer thickener.

[0020] Optionally, in some embodiments,

[0021] The thickness of the film is 10 to 40 nm;

[0022] And / or, the surface roughness of the film is 0.1 to 0.5 nm;

[0023] And / or, in the film, the content of the polymer thickener is 0.1 wt% to 10 wt%.

[0024] Optionally, in some embodiments, the polymer thickener includes one or more of a cellulose thickener, a polyacrylic thickener, and an associative polyurethane thickener, wherein:

[0025] The cellulose thickener includes one or more of methyl cellulose, ethyl cellulose, benzyl cellulose, phenyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, and benzyl cyanoethyl cellulose;

[0026] And / or, the polyacrylic thickener includes one or more of polymethacrylic acid, polymethyl methacrylate, sodium polymethacrylate, polyacrylate, etc.;

[0027] And / or, the associative polyurethane thickener includes one or more of polyether polyurethane, polyester polyurethane, and ethylene oxide polyurethane (HEUR).

[0028] Correspondingly, an embodiment of the present application further provides a light-emitting device, comprising an anode, a light-emitting layer and a cathode stacked in sequence, wherein the light-emitting layer is prepared by a film-forming process using the ink or is the thin film.

[0029] Optionally, in some embodiments, the anode and the cathode independently include a doped metal oxide electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode or an alloy electrode, and the material of the doped metal oxide 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, aluminum-doped magnesium oxide, and cadmium-doped zinc oxide; the composite electrode includes 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, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al or BaF2 / Ca / Al, the material of the metal single substance electrode includes one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg and Ba, and the alloy electrode includes Au:Mg alloy electrode or Ag:Mg alloy electrode;

[0030] And / or, the light-emitting device further comprises a hole transport layer between the anode and the light-emitting layer, and 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 One or more of fragrant 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;

[0031] And / or, the light-emitting device further comprises a hole injection layer between the anode and the light-emitting layer, and 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

[0032] 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.

[0033] Correspondingly, an embodiment of the present application further provides a display device, comprising the light-emitting device.

[0034] The polymer thickener is added to the ink described in the present application. The polymer thickener has a good ability to inhibit precipitation and stratification, so that the ink has higher stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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.

[0036] Figure 1 is a schematic structural diagram of a light-emitting device provided in an embodiment of the present application;

[0037] Figure 2 is a schematic structural diagram of another light-emitting device provided in an embodiment of the present application;

[0038] Figure 3 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0039] Figure 4 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0040] Figure 5 is a structural schematic diagram of another light-emitting device provided in an embodiment of the present application;

[0041] Figure 6 are AFM images of the light-emitting layers of Examples 1 to 12 and Comparative Examples 1 to 3 of the present application;

[0042] Figure 7 External quantum efficiency-current density curves of the light-emitting devices of Examples 1 to 12 of the present application and Comparative Examples 1 to 3.

[0043] Reference numerals:

[0044] 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

[0045] 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.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0047] 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.

[0048] 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.

[0049] In the present application, "at least one" means one or more, and "plurality" 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 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.

[0050] 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.

[0051] 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 are applicable regardless of what. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0052] Light-emitting diodes, such as organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs), have become key technologies in the display and lighting fields. Light-emitting diodes have many advantages, such as high contrast, fast response time, and wide viewing angle. Therefore, they are widely used in TVs, mobile phones, tablets, and lighting products. In the manufacture of light-emitting diode screens, the preparation of the light-emitting layer has an important impact on the display quality and device performance.

[0053] There are two main methods for preparing the light-emitting layer of light-emitting diodes: vacuum thermal evaporation and inkjet printing. The vacuum thermal evaporation method is to heat and evaporate the organic light-emitting material under vacuum conditions, and then deposit it on a glass substrate through a metal mask (FMM) to form a light-emitting layer. This method has the advantages of high preparation accuracy, good uniformity, and high material utilization, but it also has disadvantages such as high equipment cost, easy loss of the mask, and difficulty in achieving large areas and flexible substrates.

[0054] The inkjet printing method uses an inkjet print head to spray the light-emitting layer ink in the form of droplets onto a glass substrate to form a light-emitting layer. This method has the advantages of low equipment cost, no need for a mask plate, easy realization of large areas and flexible substrates, but it also has the disadvantages of low preparation accuracy, poor uniformity, and low material utilization.

[0055] The concentration of the light-emitting layer ink used in the inkjet printing method is a key parameter, which directly affects the fluidity and coating uniformity of the ink during the film-forming process. In order to improve the preparation effect of the inkjet printing method, the concentration of the light-emitting layer ink needs to be reasonably adjusted. The concentration of the light-emitting layer ink is mainly determined by the solid content of the organic light-emitting material and the type and proportion of the solvent. If the concentration of the light-emitting layer ink is too high, the viscosity of the droplets will be too high, which is not conducive to spraying and spreading, and it is easy to produce a coffee ring effect, affecting the uniformity and photoelectric performance of the light-emitting layer; if the concentration of the light-emitting layer ink is too low, the viscosity of the droplets will be too low, which is not conducive to the stability and formation of the droplets, and it is easy to cause the merging and overflow of the droplets, affecting the accuracy and resolution of the light-emitting layer.

[0056] In order to obtain the best inkjet printing effect, it is necessary to select the appropriate concentration of the luminescent layer ink according to different luminescent materials and solvents, as well as different print heads and substrates. At present, the commonly used methods for adjusting the concentration of the luminescent layer ink are as follows: changing the solid content of the organic luminescent material. Generally speaking, the higher the solid content, the higher the ink concentration, and vice versa. However, the change in solid content will also affect the physical properties of the ink such as rheology, surface tension and drying rate. Therefore, it is necessary to comprehensively consider various factors and select the appropriate solid content range; changing the type and proportion of the solvent. Generally speaking, the boiling point, viscosity and other parameters of the solvent will affect the concentration of the ink. The higher the boiling point, the greater the viscosity and the higher the ink concentration, and vice versa. Therefore, the purpose of adjusting the ink concentration can be achieved by mixing different solvents and adjusting their proportions; additives. Generally speaking, the role of additives is to improve the rheology, wettability and drying properties of the ink, thereby improving the ink jetting and spreading performance.

[0057] However, the film-forming property of existing luminescent layer inks is still relatively poor and needs to be further improved.

[0058] The technical solution of this application is as follows:

[0059] In a first aspect, an embodiment of the present application provides an ink, which is mainly used to prepare a light-emitting layer. The ink includes a light-emitting material, a polymer thickener and a solvent, wherein the polymer thickener includes one or more of a cellulose thickener, a polyacrylic thickener and an associative polyurethane thickener.

[0060] The cellulose thickener includes, but is not limited to, one or more of methylcellulose, ethylcellulose, benzyl cellulose, phenyl cellulose, hydroxypropyl methylcellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, and benzyl cyanoethyl cellulose.

[0061] The polyacrylic thickener includes, but is not limited to, one or more of polymethacrylic acid (PMA), polymethyl methacrylate, sodium polymethacrylate (PMAS), and polyacrylate.

[0062] The associative polyurethane thickener includes, but is not limited to, one or more of polyether polyurethane, polyester polyurethane, and ethylene oxide polyurethane (HEUR).

[0063] The polymer thickener is added to the ink described in the present application, and the polymer thickener has good film-forming properties, rheological properties adjustment ability, ability to inhibit precipitation and stratification, and the characteristics of improving coating uniformity. On the one hand, the polymer thickener has better film-forming properties when forming a film, so that the polymer thickener can be more evenly distributed in the luminescent layer and form a more stable and uniform film after coating; on the other hand, the polymer thickener can adjust the rheological properties of the ink, making it easier to control, which is very important for ensuring the uniformity and stability of the ink during coating; on the other hand, the polymer thickener can also more effectively inhibit the precipitation and stratification of particles in the ink to a certain extent, which helps to maintain the uniform dispersion and stability of the various components in the ink, thereby ensuring the consistency of the luminescent layer and improving the stability of the device preparation process; on the other hand, although the polymer thickener can effectively increase the viscosity of the ink, it can still maintain uniform coating, because the polymer thickener can form a network structure in the ink without excessively increasing the viscosity of the ink, and this property is very important for improving the coating uniformity. In addition, by using the polymer thickener, waste and defective rate due to uneven coating can be reduced, and the efficiency and productivity of light emitting device manufacturing can be improved.

[0064] Based on the total mass of the luminescent material and the polymer thickener, the content of the polymer thickener in the total mass is 0.1wt% to 10wt%, for example, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, etc. It depends on the type of ink, printing method, substrate and other factors. Generally speaking, the higher the mass ratio of the luminescent material, the better the luminescent effect of the ink, but it will also increase the cost and viscosity of the ink and reduce the fluidity and printability of the ink: the higher the mass ratio of the polymer thickener, the better the viscosity and stability of the ink, but it will also affect the rheology and thixotropy of the ink, causing problems such as ink sagging or line breakage. Therefore, it is necessary to select a suitable mass ratio according to the specific situation to achieve the best ink performance. The polymer thickener can also more effectively inhibit the precipitation and stratification of particles in the ink to a certain extent, which helps to maintain the uniform dispersion and stability of the components in the ink, thereby ensuring the consistency of the luminescent layer and improving the stability of the device manufacturing process.

[0065] The light-emitting material includes, but is not limited to, one or more of an organic light-emitting material and an inorganic light-emitting material.

[0066] The organic light-emitting material may include, but is not limited to, CBP:Ir(mppy)3(4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridine iridium(III)), TCTX:Ir(mmpy)(4,4',4"-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridine iridium), diaromatic anthracene derivatives, distilbene 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 delay) materials, polymers containing BN covalent bonds, HLCT (hybrid localized Charge transfer excited state) materials, Exciplex (exciplex) luminescent materials, polyacetylene and its derivatives, polyparaphenylene and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives. In some embodiments, the anthracene-based thermal exciton materials include but are not limited to one or more of PABPP (CAS: 2639255-13-1), PAC (CAS: 2414547-46-7), mPAC (CAS: 2376325-67-4), PAIDO (CAS: 2378287-85-3), PABP (CAS: 2378287-83-1), PATPA (CAS: 2420454-95-9), etc.

[0067] The chemical structure of the anthracene-based thermoexciton material is as follows:

[0068]

[0069] The inorganic luminescent material may include but is not limited to one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials. 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 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. 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 Pb2 + 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 .

[0070] The solvent includes, but is not limited to, one or more of chloroform, dichloromethane, formamide, trifluoroacetic acid, dimethyl sulfoxide (DMSO), acetonitrile, N,N-dimethylformamide (DMF), hexamethylphosphoramide, methanol, acetic acid, ethanol, isopropanol, pyridine, tetramethylethylenediamine, acetone, triethylamine, n-butanol, dioxane, tetrahydrofuran, methyl formate, tributylamine, methyl ethyl ketone, ethyl acetate, chloroform, trioctylamine, dimethyl carbonate, ethyl ether, isopropyl ether, n-butyl ether, trichloroethylene, diphenyl ether, ethylene dichloride, benzene, toluene, carbon tetrachloride, carbon disulfide, cyclohexane, and hexane.

[0071] In some embodiments, the luminescent material is an organic luminescent material, and in the ink, the concentration of the organic luminescent material is 5 to 20 mg / mL, for example, 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, etc. Within the concentration range, the spreadability of the ink can be effectively improved, which is conducive to preparing a luminescent layer with good spreadability and forming a uniform and stable thin film, thereby improving the performance and quality of the device.

[0072] In some embodiments, the luminescent material is an inorganic luminescent material, and in the ink, the concentration of the inorganic luminescent material is 5 to 40 mg / mL, for example, 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, 40 mg / mL, 45 mg / mL, 50 mg / mL, etc. Within the concentration range, the spreadability of the ink can be effectively improved, which is conducive to preparing a luminescent layer with good spreadability and forming a uniform and stable film, thereby improving the performance and quality of the device.

[0073] The viscosity of the ink described in the present application is 1 to 20 cP, for example, 1 cP, 5 cP, 10 cP, 15 cP, 20 cP, etc. Within the viscosity range, when the ink is used to form a film, it can effectively prevent the ink from flowing too fast or unevenly, improve the uniformity of the printing, achieve uniform coverage, and use different print heads and substrates.

[0074] The surface tension of the ink described in the present application is 20-40 mN / m, for example, 20 mN / m, 25 mN / m, 30 mN / m, 35 mN / m, 40 mN / m, etc. Within the range of the surface tension, the ink can have better jetting performance and spreading performance. In at least one preferred embodiment, the surface tension of the ink is 29-35 mN / m.

[0075] The present application uses a light-emitting layer ink containing a thickener, which can flexibly adjust the concentration of the ink according to different organic light-emitting materials and solvents with thinner viscosity and better solubility, as well as different print heads and substrates, thereby achieving optimal jetting and spreading performance.

[0076] By selecting a thickener with good thickening effect and low toxicity, the viscosity of the ink can be effectively increased while ensuring the solvent has good solubility, preventing the merging and overflow of droplets, and improving the stability and film-forming properties of the ink without adversely affecting the organic light-emitting materials and solvents.

[0077] In a second aspect, an embodiment of the present application further provides a method for preparing an ink, comprising: providing a luminescent material, a polymer thickener and a solvent, and mixing them to obtain the ink.

[0078] The types and proportions of the luminescent material, thickener and solvent are as described above and will not be described in detail here.

[0079] In a third aspect, the present application also provides a film, which is prepared from the ink described above by a film-forming process. In other words, the film includes the luminescent material and the polymer thickener.

[0080] In the film, the content of the polymer thickener is 0.1wt% to 10wt%, for example, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% and the like.

[0081] In some embodiments, the film has a thickness of 10 to 40 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, etc.

[0082] The surface roughness of the film is 0.1-0.5 nm.

[0083] In at least some embodiments, the film is a light-emitting film.

[0084] Fourth, please refer to Figure 1 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 prepared by the ink through a film forming process or is the thin film.

[0085] See also Figure 2 In one embodiment, 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.

[0086] See also Figure 3 In one embodiment, 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.

[0087] See also Figure 4 In one embodiment, 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 which are stacked in sequence.

[0088] See also Figure 5In one embodiment, the light emitting device 100 further includes a hole injection layer 60 located between the anode 10 and the hole transport layer 40. In other words, the light emitting device 100 includes the anode 10, the hole injection layer 60, the hole transport layer 40, the light emitting layer 20, the electron transport layer 50 and the cathode 30 stacked in sequence.

[0089] The anode 10 and the cathode 30 are electrodes for light-emitting devices known in the art, for example, they can be independently and independently include but are not limited to doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, metal single substance electrodes or alloy electrodes. The material of the doped metal oxide electrode can be but is 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), aluminum doped magnesium oxide (AMO), and cadmium doped zinc oxide. The composite electrode is an electrode formed by stacking two or more layers of conductive materials, 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, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc., wherein " / " represents a stacked structure, for example, AZO / Ag / AZO represents a composite electrode including a sequentially stacked AZO layer, an Ag layer and an AZO layer. The material of the metal single substance electrode may include but is not limited to one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg and Ba. The alloy electrodes include but are not limited to Au:Mg alloy electrodes and Ag:Mg alloy electrodes.

[0090] In some embodiments, the anode is an electrode with a relatively high work function, for example, it may include but is not limited to a doped metal oxide electrode with a relatively high work function, a metal single substance electrode with a relatively high work function, and a carbon nanotube electrode. The metal single substance electrode with a relatively high work function may be selected from but is not limited to Ni, Pt, Au, Ag, Ir, etc.

[0091] In some embodiments, the cathode is an electrode with a relatively low work function, for example, it may include but is not limited to a metal single substance electrode with a relatively low work function, a composite electrode with a relatively low work function, and an alloy electrode with a relatively low work function. The metal single substance electrode with a relatively low work function may be Ca, Ba, Al, Mg, etc. The composite electrode with a relatively low work function may be Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. The alloy electrode with a relatively low work function may be Au:Mg and Ag:Mg, etc.

[0092] The material of the hole transport layer 40 can be a material known in the art for a hole transport layer, for example, can be selected from but 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), N (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.

[0093] The material of the electron transport layer 50 is a material known in the art for an electron transport layer, for example, it can be selected from but not limited to one or more of an inorganic electron transport material and an organic electron transport material.

[0094] The inorganic electron transport material includes, but is not limited to, one or more of doped metal oxide particles, non-doped metal oxide particles, ceramic semiconductor materials, IIB-VIA semiconductor materials, IIIA-VA semiconductor materials, and IB-IIIA-VIA semiconductor materials. The metal oxide in the non-doped metal oxide particles includes, but is not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxide in the doped metal oxide includes, but is not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the doped metal oxide include, but are not limited to, one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, and Sn. As an example, the doped metal oxide can be aluminum zinc oxide (AZO), lithium-doped zinc oxide (LZO), magnesium-doped zinc oxide (MZO), tin-doped zinc oxide (Sn-ZnO), etc. The ceramic semiconductor material includes, but is not limited to, barium titanate. The IIB-VIA semiconductor materials include but are not limited to one or more of ZnS, ZnSe, and CdS. The IIIA-VA semiconductor materials include but are not limited to one or more of InP and GaP. The IB-IIIA-VIA semiconductor materials include but are not limited to one or more of CuInS and CuGaS.

[0095] The organic electron transport material includes but is not limited to 8-hydroxyquinoline aluminum (Alq3), diphenyl [4- (triphenylsilyl) phenyl] phosphine oxide (TSPO1), 1,3,5-tris ((3-pyridyl)-3-phenyl) benzene (TmPyPB), 2- (4-biphenyl) -5-phenyl oxadiazole (PBD), bis (10-hydroxybenzo [h] quinolinol) beryllium (Bebq2) (CAS: 148896-39-3), 3- (biphenyl-4-yl) -5- (4-tert-butylphenyl) -4-phenyl -4H-1,2,4-triazole (TAZ), 2,7-bis (diphenylphosphinyl) -9,9'-spirobis [fluorene] (S PPO13), 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI), 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine (B3PYMPM), 4,7-diphenyl-1,10-phenanthroline (BPhen), 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2,9-dimethyl-4,7-diphenyl-1,10-o-phenanthroline, 4,7-diphenyl-1,10-o-phenanthroline, bis(2-methyl-8-hydroxyquinoline-N1,O8)-1,1'-biphenyl-4-hydroxy)aluminum or more.

[0096] 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.

[0097] The material of the electron injection layer 70 may be a material known in the art for an electron injection layer, for example, may be selected from but not limited to at least one of Li, cesium carbonate, cesium fluoride, cesium azide and lithium fluoride.

[0098] 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.

[0099] 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 .

[0100] 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 .

[0101] 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.

[0102] 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.

[0103] The light-emitting layer 20 of the light-emitting device 100 includes the quantum dots described in the present application, thereby having higher light-emitting efficiency and longer lifespan.

[0104] The present application also relates to a display device, which includes the light-emitting device 100 .

[0105] 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.

[0106] The present application is described in detail below by means of specific examples, which are only partial examples of the present application and are not intended to limit the present application. The raw materials used in the following examples are all commercially available products unless otherwise specified.

[0107] Example 1

[0108] The transparent conductive film ITO is used as the anode, and the thickness of the anode is 50nm;

[0109] Depositing a PEDOT:PSS material on the anode by a solution method to obtain a hole injection layer with a thickness of 30 nm;

[0110] Depositing PVK material on the hole injection layer by a solution method to obtain a hole transport layer with a thickness of 20 nm;

[0111] Depositing ink on the hole transport layer by a solution method, the ink comprising PAC (luminescent material), methyl cellulose (thickener) and solvent chloroform, wherein the mass ratio of the luminescent material to the thickener is 99:1, the concentration of the luminescent material PAC is 10 mg / mL, and a luminescent layer with a thickness of 35 nm is obtained;

[0112] Depositing SPPO13 material on the light-emitting layer by evaporation to obtain an electron transport layer with a thickness of 30 nm;

[0113] Depositing Li material on the electron transport layer by evaporation to obtain an electron injection layer with a thickness of 100 nm;

[0114] Depositing Al material on the electron injection layer by evaporation to obtain a cathode with a thickness of 100 nm;

[0115] The light emitting device OLED is obtained by packaging.

[0116] Example 2

[0117] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 98:2.

[0118] Example 3

[0119] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 97:3.

[0120] Example 4

[0121] This embodiment is substantially the same as Embodiment 1, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 96:4.

[0122] Example 5

[0123] This embodiment is substantially the same as Embodiment 1, except that the thickener in this embodiment is hydroxypropyl methylcellulose.

[0124] Example 6

[0125] This embodiment is basically the same as Embodiment 5, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 98:2.

[0126] Example 7

[0127] This embodiment is basically the same as Embodiment 5, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 97:3.

[0128] Example 8

[0129] This embodiment is basically the same as Embodiment 5, except that, in this embodiment, the mass ratio of the luminescent material to the thickener is 96:4.

[0130] Example 9

[0131] This embodiment is substantially the same as Embodiment 1, except that the thickener of this embodiment is a polyacrylic thickener, polymethacrylic acid.

[0132] Example 10

[0133] This embodiment is substantially the same as Embodiment 1, except that the thickener in this embodiment is ethylene oxide polyurethane (HEUR).

[0134] Embodiment 11

[0135] This embodiment is basically the same as Embodiment 1, except that the luminescent material of this embodiment is PABP.

[0136] Example 12

[0137] This embodiment is basically the same as Embodiment 1, except that the luminescent material of this embodiment is PATPA.

[0138] Comparative Example 1

[0139] This comparative example is basically the same as Example 2, except that the preparation method of the light-emitting layer in this comparative example includes:

[0140] Ink was deposited on the hole transport layer by a solution method. The ink included PAC (luminescent material) and solvent chloroform. The concentration of the luminescent material PAC was 10 mg / mL, and a luminescent layer with a thickness of 35 nm was obtained.

[0141] That is, the luminescent material of this comparative example is PAC.

[0142] Comparative Example 2

[0143] This comparative example is basically the same as Example 2, except that the thickener in this comparative example is GPP shown in formula (1-1):

[0144]

[0145] Comparative Example 3

[0146] This comparative example is basically the same as Example 2, except that the thickener in this comparative example is PNDOF shown in formula (1-2):

[0147]

[0148] Ink performance test:

[0149] The inks of Examples 1 to 12 and Comparative Examples 1 to 3 were tested for stability, viscosity, and surface tension. The test results are shown in Table 1.

[0150] The ink stability test method is to place the ink for 60 days to test whether the ink has precipitation and stratification. The viscosity of the ink is measured by a viscometer. The surface tension of the ink is measured by a surface tension measuring instrument.

[0151] Table 1:

[0152]

[0153]

[0154] From Table 1 we can see that:

[0155] The inks of Examples 1 to 12 had no stratification and no precipitation after being placed for 60 days, while the inks of Comparative Examples 1 to 3 had stratification and precipitation after being placed for 60 days. It can be seen that the inks of the present application have good stability, which may be due to the fact that the polymer thickener of the present application has a good ability to inhibit precipitation and stratification;

[0156] Compared with the ink of comparative examples 1 to 3, the ink of examples 1 to 12 has higher viscosity and higher surface tension. The reason may be that the ink of examples 1 to 12 contains the polymer thickener described in the present application, and the polymer thickener described in the present application can adjust the rheological properties of the ink and increase the viscosity of the ink.

[0157] Device performance test:

[0158] The light-emitting layers of Examples 1 to 12 and Comparative Examples 1 to 3 were tested by AFM, and the results were Figure 6 The AFM image shown in the figure shows the surface roughness of the light-emitting layer. The test results are shown in Table 2 and Figure 6 .

[0159] The driving voltage, external quantum efficiency and lifespan T95 test were performed on the light emitting devices of Examples 1 to 12 and Comparative Examples 1 to 3, respectively, and the V@10mA / cm 2 ,EQE@10mA / cm 2 、T95@1000cd / m 2 , where V@10mA / cm 2 Indicates that the current density is 10mA / cm 2 The corresponding driving voltage is EQE@10mA / cm 2 Indicates that the current density is 10mA / cm 2 Corresponding EQE: T95@1000cd / m 2 It means that the device has an initial brightness of 1000cd / m2 When the brightness decays to 95% of the initial brightness (here 950cd / m 2 ) is the time it takes to complete the test. The test results are shown in Table 2 and Figure 7 .in, Figure 7 This is the external quantum efficiency-current density curve.

[0160] The driving voltage of the light-emitting device is 10 mA / cm 2 The corresponding driving voltage.

[0161] The test method for the external quantum efficiency EQE of a light-emitting device is: the ratio of the number of electron-hole pairs injected into quantum dots to the number of emitted photons, in %, which is an important parameter for measuring the quality of electroluminescent devices and can be obtained by measuring with an EQE optical test instrument. The specific calculation formula is as follows:

[0162]

[0163] Where ηe is the light output coupling efficiency, ηr is the ratio of the number of recombined carriers to the number of injected carriers, χ is the ratio of the number of excitons that generate photons to the total number of excitons, and K R is the radiation process rate, K NR is the rate of the non-radiative process.

[0164] The test method for the lifespan T95 of a light-emitting device is: the time required for the brightness of the device to decrease to a certain proportion of the maximum brightness when the device is driven by a constant current of 2mA. The time when the brightness drops to 95% of the maximum brightness is defined as T95, and this lifespan is the measured lifespan. In order to shorten the test cycle, the device lifespan test is usually carried out at high brightness by accelerating device aging, and the lifespan at high brightness is obtained by fitting the extended exponential decay brightness attenuation fitting formula. For example, the lifespan at 1000nit is calculated as T95@1000nit. The specific calculation formula is as follows:

[0165]

[0166] Among them, T95 L For lifespan at low brightness, T95 H is the measured lifetime under high brightness, L H To accelerate the device to the highest brightness, L L is 1000nit, A is the acceleration factor, and this experiment measured the lifespan of several groups of green OLED devices at rated brightness and obtained an A value of 1.7.

[0167] The environmental conditions of the above test are: carried out at room temperature and air humidity is 30-60%.

[0168] Table 2:

[0169]

[0170]

[0171] From Table 2 and Figure 6 It can be seen that:

[0172] Compared with the surface roughness of the light-emitting layer of comparative examples 1 to 3, the surface roughness of the light-emitting layer of embodiments 1 to 12 is significantly lower. The reason may be that the ink of the present application has good film-forming properties, rheological properties adjustment ability, ability to inhibit precipitation and stratification, and improved coating uniformity.

[0173] From Table 2 and Figure 7 It can be seen that:

[0174] Compared with the devices of comparative examples 1 to 3, the devices of embodiments 1 to 12 have lower driving voltage, higher luminous efficiency and longer life. It can be seen that the use of the ink of the present application to prepare the light-emitting layer of the light-emitting device can effectively reduce the driving voltage during the period, and improve the luminous efficiency and life of the device. The reason may be that the ink of the present application has good film-forming properties, rheological properties adjustment capabilities, the ability to inhibit precipitation and stratification, and the characteristics of improving coating uniformity, so that the prepared light-emitting layer can have good film-forming properties, lower roughness and higher stability.

[0175] 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. An ink, characterized in that: It includes a luminescent material, a polymer thickener and a solvent.

2. The ink according to claim 1, characterized in that: Based on the total mass of the luminescent material and the polymer thickener, the content of the polymer thickener accounts for 0.1 wt% to 10 wt% of the total mass.

3. The ink according to claim 1, characterized in that: The polymer thickener includes one or more of a cellulose thickener, a polyacrylic thickener, and an associative polyurethane thickener.

4. The ink as claimed in claim 3, characterized in that: The cellulose thickener includes one or more of methyl cellulose, ethyl cellulose, benzyl cellulose, phenyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, and benzyl cyanoethyl cellulose; And / or, the polyacrylic thickener includes one or more of polymethacrylic acid, polymethyl methacrylate, sodium polymethacrylate, and polyacrylate; And / or, the associative polyurethane thickener includes one or more of polyether polyurethane, polyester polyurethane, and ethylene oxide polyurethane.

5. The ink according to claim 1, characterized in that: The luminescent material includes one or more of an organic luminescent material and an inorganic luminescent material, wherein: The organic light-emitting material includes 4,4'-bis(N-carbazole)-1,1'-biphenyl:tri[2-(p-tolyl)pyridine iridium(III), 4,4',4"-tri(carbazole-9-yl)triphenylamine:tri[2-(p-tolyl)pyridine iridium, diaromatic anthracene derivatives, distilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescent materials, TTA materials, thermally activated delayed materials, polymers containing BN covalent bonds, hybrid localized charge transfer excited state materials, exciplex light-emitting materials, polyacetylene and its derivatives, polyparaphenylene and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives, and the anthracene-based thermal exciton material includes one or more of PABPP, PAC, mPAC, PAIDO, PABP, and PATPA; And / or, the inorganic luminescent material includes one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials, 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 are independently selected from 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, One or more of ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound includes SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSe The III-V group compound includes 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, GaA lNAs, 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 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 .

6. The ink according to any one of claims 1 to 4, characterized in that: The luminescent material is an organic luminescent material, and in the ink, the concentration of the organic luminescent material is 5 to 30 mg / mL; And / or, the luminescent material is an inorganic luminescent material, and the concentration of the inorganic luminescent material in the ink is 5 to 40 mg / mL; and / or, the viscosity of the ink is 1 to 20 cP; And / or, the surface tension of the ink is 20-40 mN / m, preferably, the surface tension of the ink is 29-35 mN / m; And / or, the solvent includes one or more of chloroform, dichloromethane, formamide, trifluoroacetic acid, dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, hexamethylphosphoramide, methanol, acetic acid, ethanol, isopropanol, pyridine, tetramethylethylenediamine, acetone, triethylamine, n-butanol, dioxane, tetrahydrofuran, methyl formate, tributylamine, methyl ethyl ketone, ethyl acetate, chloroform, trioctylamine, dimethyl carbonate, ethyl ether, isopropyl ether, n-butyl ether, trichloroethylene, diphenyl ether, ethylene dichloride, benzene, toluene, carbon tetrachloride, carbon disulfide, cyclohexane, and hexane.

7. A film, characterized in that: The film is prepared by a film-forming process using the ink described in any one of claims 1 to 6; Alternatively, the material of the film includes a light-emitting material and a polymer thickener.

8. The film according to claim 7, characterized in that: The thickness of the film is 10 to 40 nm; And / or, the surface roughness of the film is 0.1 to 0.5 nm; And / or, in the film, the content of the polymer thickener is 0.1 wt% to 10 wt%.

9. The film according to claim 7, characterized in that: The polymer thickener includes one or more of a cellulose thickener, a polyacrylic thickener, and an associative polyurethane thickener, wherein: The cellulose thickener includes one or more of methyl cellulose, ethyl cellulose, benzyl cellulose, phenyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, and benzyl cyanoethyl cellulose; And / or, the polyacrylic thickener includes one or more of polymethacrylic acid, polymethyl methacrylate, sodium polymethacrylate, polyacrylate, etc.; And / or, the associative polyurethane thickener includes one or more of polyether polyurethane, polyester polyurethane, and ethylene oxide polyurethane.

10. A light emitting device, characterized in that: The invention comprises an anode, a light-emitting layer and a cathode which are stacked in sequence, wherein the light-emitting layer is prepared by a film-forming process using the ink described in any one of claims 1 to 6 or is a film described in any one of claims 7 to 9.

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