Functional film layer, preparation method thereof and light-emitting device

Abstract

The invention belongs to the technical field of display, and relates to a functional film layer, a preparation method thereof and a light-emitting device. The functional film layer comprises a functional material and a P-type doped material; wherein the difference value between the HOMO energy level absolute value of the functional material and the LUMO energy level absolute value of the P-type doped material is 0.1 eV to 1 eV. As the difference value between the HOMO energy level absolute value of the functional material and the LUMO energy level absolute value of the P-type doped material is 0.1 eV to 1eV, electrons in a conduction band of the P-type doped material can be relaxed to a valence band of the functional material according to a photovoltaic effect, so that the valence band of the functional material has a large number of freely movable holes, the conductivity of the functional film layer is further improved, and the photoelectric conversion efficiency is improved. And the service life of the functional film layer is prolonged.

Description

Technical Field

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

[0002] Optical display effect refers to the effect of presenting information to the observer in the form of light in a light-emitting device, including brightness, contrast, response speed, etc. Functional film layers such as hole transport layers prepared by the preparation method of functional film layers in the prior art have low conductivity and unbalanced carriers, resulting in poor performance of light-emitting devices. Summary of the invention

[0003] The technical problem to be solved by the embodiments of the present application is the technical problem that the light emitting devices in the prior art have high driving voltage, poor optical display effect and short device life.

[0004] In order to solve the above technical problems, the embodiment of the present application provides a functional film layer, and the functional film layer adopts the following technical solution:

[0005] A functional film layer, wherein the material of the functional film layer comprises a functional material and a P-type doping material;

[0006] Wherein, the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1 eV to 1 eV.

[0007] Furthermore, the absolute value of the LUMO energy level of the P-type doping material is ≥5 eV; and / or,

[0008] The absolute value of the HOMO energy level of the functional material is 5.1 eV to 6 eV.

[0009] Further, the P-type doping material is at least one of Cu2O, CuSCN, MoO3, WoO3, NiO, CuO, and V2O5; and / or,

[0010] The P-type doping material includes phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO 3 、V 2 At least one of O5 and WO3.

[0011] Accordingly, the present application also provides a method for preparing a functional film layer, the method comprising:

[0012] Provide base film, functional material precursor, P-type doping material, and solvent;

[0013] Mixing the functional material precursor, the P-type doping material, and the solvent to obtain a mixed solution;

[0014] placing the mixed solution on the base film and performing a solvent removal process to obtain the functional film layer;

[0015] The functional film layer includes a functional material formed by transformation of a functional material precursor, and the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1 eV to 1 eV.

[0016] Further, the functional material precursor includes any one of doped or undoped metal oxides, doped or undoped metal sulfides, doped or undoped metal selenides or a combination thereof; and / or,

[0017] The absolute value of the LUMO energy level of the P-type doping material is ≥5eV; and / or,

[0018] The absolute value of the HOMO energy level of the functional material is 5.1 eV to 6 eV.

[0019] Furthermore, before the step of placing the mixed solution on the base film, the following steps are also included:

[0020] The functional material precursor, the P-type doping material and the solvent are mixed to prepare the mixed solution, wherein the mass ratio of the functional material precursor to the P-type doping material is (50:1) to (1:1).

[0021] Further, the functional material precursor includes any one or a combination of nickel chloride, nickel acetylacetonate, nickel acetate, nickel nitrate, and nickel sulfate;

[0022] And / or, the P-type doping material includes phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO 3 、V 2 Either O5 or WO3.

[0023] Further, the step of removing the solvent comprises:

[0024] The base film containing the mixed solution is placed in an oxygen-containing environment for baking treatment, the baking temperature is 200° C. to 250° C., and the solvent removal treatment time is 30 min to 60 min.

[0025] Furthermore, after the step of obtaining the functional film layer, the following steps are also included:

[0026] Immersing the functional film layer in a silsesquioxane derivative solution;

[0027] The functional film layer is subjected to light treatment to form a SiO2 passivation layer on the surface of the functional film layer.

[0028] Furthermore, the silsesquioxane derivative solution includes any one of PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl, PSS-octa[2-(p-carboxyphenyl)ethyl], octa[2-(4-carboxy-1,1-biphenyl)ethyl], PSS-(3-mercapto)propyl-heptaisobutyl or a combination thereof.

[0029] Furthermore, the light energy density of the light treatment is 1mW / cm 2 ~500mW / cm 2 and / or,

[0030] The wavelength of the light used in the illumination treatment is 200nm to 380nm; and / or,

[0031] The light irradiation time of the light treatment is 5 minutes to 100 minutes.

[0032] Furthermore, the base film includes a hole injection layer film, and the material of the hole injection layer film includes phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, CuSCN, nickel oxide, cuprous iodide, and any one or a combination of nanoparticles of MoO3, V2O5 or WO3.

[0033] Accordingly, the present application provides a light-emitting device, which includes a bottom electrode, a hole functional layer, a light-emitting layer, an electron functional layer, and a top electrode;

[0034] Wherein, the hole functional layer is the functional film layer as described above, or is prepared by any of the preparation methods of the functional film layer as described above.

[0035] Furthermore, the light emitting device further comprises a light emitting layer and a SiO2 passivation layer, wherein the SiO2 passivation layer is arranged between the light emitting layer and the hole transport layer, and the thickness of the SiO2 passivation layer is 0.5 nm to 3 nm.

[0036] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0037] Since the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1eV to 1eV, according to the photovoltaic effect, the electrons in the conduction band of the P-type doping material will relax to the valence band of the functional material, so that the valence band of the functional material has a large number of freely movable holes, thereby improving the conductivity of the functional film layer, and thus improving the life of the functional film layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the solutions in the present application or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 is a flow chart of a method for preparing a functional film layer according to an embodiment of the present application;

[0040] Figure 2 Structural diagram of a light-emitting device according to an embodiment of the present application.

[0041] Reference numerals:

[0042] Substrate 100 , electrode 200 , hole injection layer 300 , hole transport layer 400 , SiO 2 passivation layer 500 , light emitting layer 600 , electron transport layer 700 , cathode 800 . DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple, respectively.

[0047] 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.

[0048] The embodiment of the present application provides a functional film layer, wherein the material of the functional film layer includes a functional material and a P-type doping material; wherein the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1eV to 1eV. Since the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1eV to 1eV, according to the photovoltaic effect, the electrons in the conduction band of the P-type doping material will relax to the valence band of the functional material, so that the valence band of the functional material has a large number of holes that can move freely, thereby improving the conductivity of the functional film layer, and thereby improving the life of the functional film layer.

[0049] Further, the absolute value of the LUMO energy level of the P-type doping material is ≥5eV; and / or the absolute value of the HOMO energy level of the functional material is 5.1eV to 6eV. It is understood that the absolute value of the HOMO energy level of the functional material can be any one of 5.1eV, 5.2eV, 5.3eV, 5.4eV, 5.5eV, 5.6eV, 5.7eV, 5.8eV, 5.9eV, and 6eV, or a range formed by any two of the values.

[0050] Further, the P-type doping material is at least one of Cu2O, CuSCN, MoO3, WoO3, NiO, CuO, and V2O5; and / or, the P-type doping material includes phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO3 、V 2 At least one of O5 and WO3.

[0051] The technical solution of this application is as follows:

[0052] Please refer to Figure 1 The present invention provides a method for preparing a functional film layer, comprising the following steps:

[0053] S100, providing base film, functional material precursor, P-type doping material, and solvent;

[0054] S200, mixing a functional material precursor, a P-type doping material, and a solvent to obtain a mixed solution;

[0055] S300, placing the mixed solution on the base film, performing a desolventizing treatment, and obtaining a functional film layer.

[0056] Among them, the functional film layer includes a functional material formed by the transformation of the functional material precursor, and the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1eV~1eV. First, the ratio of the absolute value of the HUMO energy level of the functional material of the present application to the absolute value of the LUMO energy level of the P-type doping material is 0.1eV~1eV. Therefore, when the embodiment of the present application uses the functional material precursor and the P-type doping material to form a mixed material body, a quasi-oxidation doping reaction occurs between the P-type doping material and the functional material precursor, but precipitation, acid oxidation and other phenomena will not occur between the two materials, and ink can be configured to form, and at the same time, it can improve the balance of carriers. Therefore, this embodiment can improve the conductivity of the functional film layer and balance the carriers, thereby reducing the driving voltage of the light-emitting device and improving the optical display effect of the light-emitting device. It can be understood that the quasi-oxidation doping reaction process is to form a functional material for the functional material precursor during the desolvation process. At this time, the P-type doping material reacts with the functional material, and an electron in the valence band of the functional material is transferred to the conduction band of the P-type doping material.

[0057] Further, the P-type doping material is an inorganic P-type doping material. At this time, compared with the organic P-type doping material, the advantages of this embodiment are as follows: good stability, not easily affected and degraded by the external environment, good carrier balance, and the crystal structure of the inorganic P-type doping material is orderly and tight, which is conducive to the efficient transmission of holes. Secondly, the mixing of inorganic P-type doping materials and organic hole transport materials (such as polyvinyl carbazole, N'-diphenyl-N, C60) will not cause acidic oxidation and / or precipitation between the two components. The organic p-doping material, as an acid or oxidant, will catalyze the cross-linking of the organic hole transport material, and this cross-linking reaction can usually occur at room temperature, resulting in the organic P-type doping material and the organic hole transport material. It is impossible to configure the ink, or, although some organic P-type dopants will not undergo such catalytic cross-linking, the doping effect is insufficient and the carrier balance effect cannot be achieved. In summary, when the P-type doping material of the present application is an inorganic P-type doping material, it can further improve the conductivity of the functional film layer and balance the carriers, thereby reducing the driving voltage of the light-emitting device and improving the optical display effect of the light-emitting device.

[0058] Understandably, please refer to Figure 2 , the functional film layer of the embodiment of the present application can be used as an electron transport layer. At this time, the light-emitting device including the functional film layer can also include structures such as an electrode 200, a hole injection layer 300, a light-emitting layer 600, and a cathode 700. The hole transport layer 400 can be formed on the electrode 200, the hole transport layer 400, and the light-emitting layer 600. Structures such as the hole injection layer 300, the hole transport layer 400, and the light-emitting layer 600 can be prepared by spraying, front coating, spin coating, and printing. The steps mentioned in this application, such as "arranging the mixed solution on the base film", etc., which involve processes for treating the base film, should all be understood as treating the substrate 100 and / or the remaining structures on the substrate 100 (such as the electrode 200, the hole injection layer 300, the hole transport layer 400, the SiO2 passivation layer, 500, the light-emitting layer 600 and other film layers).

[0059] When the electrode 200 needs to be prepared, the electrode 200 on the substrate 100 can be cleaned before step S100 and treated under UV (ultraviolet) conditions for 10 minutes to 15 minutes to increase the work function and wettability of the electrode 200. The treatment time under UV (ultraviolet) conditions can be any one of 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, and 15 minutes, or a range formed by any two of the values. The electrode includes an anode or a cathode, and its material includes one or more of metal, carbon material and metal oxide, the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene and carbon fiber; the metal oxide includes doped or undoped metal oxide, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO and AMO, or includes a composite electrode with metal sandwiched between doped or undoped transparent metal oxides, and 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, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2 and TiO2 / Al / TiO2. The manufacturing process includes but is not limited to thin film deposition, photolithography, printing, and plasma etching. It is preferred to use a top-emitting reflective electrode, such as a laminated structure of conductive metals and conductive metal oxides such as ITO / Ag / ITO and IZO / Ag / IZO.

[0060] When the hole injection layer 300 needs to be prepared, the material of the hole injection layer 300 includes at least one of TFB, CuPc, PEDOT:PSS, F4-TCNQ, HATCN, transition metal oxides, transition metal sulfides, transition metal tinides, doped graphene, undoped graphene and C60.

[0061] When it is necessary to prepare the light-emitting layer 600, the material of the light-emitting layer 600 includes at least one of a single structure quantum dot and a core-shell structure quantum dot, and the material of the single structure quantum dot, the core material of the core-shell structure quantum dot and the shell material of the core-shell structure quantum dot are respectively selected from at least one of a II-VI group compound, a IV-VI group compound, a III-V group compound and a I-III-VI group compound, wherein the II-VI group compound includes but is not limited to 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, and Group IV-VI compounds include but are not limited to SnS, SnSe, SnTe, PbS , PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe, and III-V compounds include but are not limited to GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlN One or more of Sb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; and Group I-III-VI compounds include but are not limited to at least one of CuInS2, CuInSe2 and AgInS2.

[0062] In the mixed solution, if the content of functional material precursor is too high relative to the P-type doping material, it will lead to the following problems: the P-type doping material is diluted, thereby reducing the conductivity of holes; increasing the energy band barrier of the hole transport layer; increasing the resistance of the hole transport layer, resulting in an increase in the current transmission resistance of the device, affecting the conductivity and response speed of the device. At the same time, insufficient relative content of functional material precursor may lead to the following problems: the concentration of P-type doping is not high enough, which may lead to increased recombination of electrons and holes, reduce the transmission efficiency of holes, and thus affect the long-term performance stability of the device. Therefore, when preparing a mixed solution, it is necessary to consider the mass ratio of functional material precursor and P-type doping material.

[0063] In some embodiments. The functional material precursor includes any one or a combination of doped or undoped metal oxides, doped or undoped metal sulfides, doped or undoped metal selenides; and / or, the absolute value of the LUMO energy level (the absolute value of the lowest unoccupied molecular orbital energy level) of the P-type doping material is ≥5eV; and / or, the absolute value of the HOMO energy level of the functional material is 5.1eV to 6eV. It can be understood that the absolute value of the HOMO energy level of the functional material can be any one of 5.1eV, 5.2eV, 5.3eV, 5.4eV, 5.5eV, 5.6eV, 5.7eV, 5.8eV, 5.9eV, and 6eV, or the range formed by any two values. At this time, the bandgap width of the conduction band of the functional material and the P-type doping material is narrow, and the efficiency of electron transfer from the valence band of the functional material to the P-type doping material is high, so the functional material precursor doped with the P-type doping material can make the hole transport layer 400 have good electron transport performance, stability and durability.

[0064] In summary, after the functional material precursor is doped with a P-type doping material to form a mixed material body, the functional film layer has a large number of holes / electrons that can move freely, and the conductivity can be improved. It does not have the effect of blocking carriers or excitons. The functional film layer (such as a hole transport layer) will achieve carrier balance, high conductivity, and good optical display effects. When the absolute value of the HOMO energy level of the functional material is 5.1eV to 6eV, it can improve the efficiency and number of electron transfer on the final functional material oxide, thereby improving the external quantum efficiency and service life of the final functional film layer.

[0065] It is understood that the doped or undoped metal oxide, doped or undoped metal sulfide, doped or undoped metal selenide includes any one of CrOx, CuO, NiOx, MoSx, MoSex, WSx, WSex, CuSx, MoSx or a combination thereof, wherein 1≤x≤3; wherein the doping method includes but is not limited to aluminum doping, gallium doping, indium doping, magnesium doping, copper doping, yttrium doping oxygen, cobalt doping, manganese doping, cadmium doping, lithium doping or a combination thereof. The absolute value of the LUMO energy level of the P-type doping material may be greater than or equal to 5eV, greater than or equal to 5.2eV, greater than or equal to 5.4eV, greater than or equal to 5.6eV, greater than or equal to 5.8eV, greater than or equal to 6eV, greater than or equal to 6.2eV, greater than or equal to 6.4eV, greater than or equal to 6.6eV, greater than or equal to 6.8eV, greater than or equal to 7eV.

[0066] In some embodiments, before step S200, the following steps are also included: mixing a functional material precursor, a P-type doping material and a solvent to prepare a mixed solution, in which the mass ratio of the functional material precursor and the P-type doping material is (50:1) to (1:1). At this time, the driving voltage of the hole transport layer 400 is low, the conductivity is high, and the device life is long. It is understandable that the mass ratio of the functional material precursor and the P-type doping material can be equal to any value of 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 2, 1 or a range formed by any two values. Because the mixed solution of this embodiment is prepared by a precursor, the mixed solution can be evenly dispersed, and the concentration and viscosity of the mixed solution can be adjusted to make it suitable for a specific coating process, and the crystal structure and morphology of the material can also be controlled to achieve the effect of optimizing the performance of the material and the electronic transmission characteristics.

[0067] It is understandable that the above solvent includes any one or a combination of water, methanol, ethanol, isopropanol, n-butanol, tert-butanol, n-hexanol, n-heptanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, acetonitrile, cyclohexanone, dioxane, dimethyl sulfoxide, tetrahydrofuran, and chloroform.

[0068] In some embodiments, the functional material precursor includes any one or a combination of nickel chloride, nickel acetylacetonate, nickel acetate, nickel nitrate, and nickel sulfate; and / or, the P-type doping material includes any one or a combination of phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO3, V2O5, and WO3. At this time, nickel oxide has high chemical stability and thermal stability under normal conditions, and can maintain good performance and electron transport characteristics, and the above-mentioned P-type doping materials will not react with nickel oxide to cause acidic oxidation, precipitation, and other adverse reactions that affect the display effect of the light-emitting device. Therefore, when the functional material precursor, P-type doping material, and solvent are mixed to form a mixed solution, the present embodiment can avoid adverse reactions inside the mixed solution, thereby improving the conductivity and optical display effect of the hole transport layer 400 finally made.

[0069] In some embodiments, the step of performing a desolventizing treatment includes: placing the base film containing the mixed solution in an oxygen-containing environment for baking treatment, the baking temperature is 200°C to 250°C, and the baking time is 30min to 60min. Therefore, the drying temperature of the mixed solution in the embodiment of the present application can make the solvent in the mixed solution volatilize at an appropriate rate, and the functional material precursor and the P-type doping material can be fully gathered on the substrate 100 to form a compact film structure, ensuring the conductive performance and stability of the hole transport layer 400. At the same time, it can avoid the substrate 100, the electrode 200, the hole transport layer 400 and other structures in the base film from pyrolysis or oxidation reaction, resulting in changes in the properties of the light-emitting device, and even affecting the stability and performance of the device. Further, the baking time of the present application can ensure that the solvent is fully volatilized, so that the functional material precursor and the P-type doping material are evenly distributed on the substrate 100, forming a uniform film, improving the conductive performance and optical display effect. Avoid excessive sintering of the hole transport layer 400, forming an overly dense film, affecting the transmission of holes, and reducing device performance. Finally, because the inorganic hole material precursor of the mixed solution of the embodiment of the present application needs to form a metal oxide, the drying needs to be carried out in an environment with oxygen, such as an air environment, nitrogen oxygen, or ozone environment.

[0070] It is understood that the baking temperature may be any one of 200° C., 205° C., 210° C., 215° C., 220° C., 225° C., 230° C., 235° C., 240° C., 245° C., and 250° C., or a range formed by any two of the above-mentioned values. The baking time may be any one of 30 min., 32 min., 34 min., 36 min., 38 min., 40 min., 42 min., 44 min., 46 min., 48 min., 50 min., 52 min., 54 min., 56 min., 58 min., and 60 min., or a range formed by any two of the above-mentioned values.

[0071] In some embodiments, after step S300, the following steps are also included: immersing the functional film layer in a silsesquioxane derivative solution; at this time, the end groups in the silsesquioxane derivative solution interact with the surface of the functional film layer to self-assemble. The substrate is then subjected to light treatment to form a SiO2 passivation layer on the surface of the functional film layer. Since there are usually defects on the surface of the functional film layer, the light-emitting layer may be quenched, thereby affecting the life of the light-emitting device. Therefore, the SiO2 passivation layer of the embodiment of the present application can form an insulating layer between the light-emitting layer and the hole transport layer, which can prevent the light-emitting layer 600 from being quenched. At the same time, the embodiment of the present application adopts a self-assembly method to prepare a SiO2 passivation layer on the surface of the functional film layer, which can reduce the thickness of the SiO2 passivation layer and avoid the excessively thick SiO2 passivation layer causing the conductivity of the light-emitting device to decrease, the current to decrease, and the driving voltage to increase. It can be understood that the substrate mentioned in the present application

[0072] In some embodiments, the silsesquioxane derivative solution includes any one of PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl, PSS-octa[2-(p-carboxyphenyl)ethyl], octa[2-(4-carboxy-1,1'-biphenyl)ethyl], PSS-(3-mercapto)propyl-heptaisobutyl or a combination thereof. The silsesquioxane derivative solution is a precursor solution of the SiO2 passivation layer, so the composition of the silsesquioxane derivative solution will affect the self-assembly ability and film thickness controllability of the SiO2 passivation layer. The embodiment of the present application uses the above-mentioned silsesquioxane derivative solution containing the above-mentioned materials to form a uniform and dense SiO2 passivation layer 500 on the surface of the hole transport layer material, and at the same time, the concentration and treatment time of the silsesquioxane derivative solution can be adjusted to more accurately form a SiO2 passivation layer of a preset thickness.

[0073] In some embodiments, the light energy density of the light treatment is 1 mW / cm 2 ~500mW / cm 2 ; and / or, the wavelength includes 200nm~380nm; and / or, the irradiation time includes 5min~100min. The energy density, wavelength and irradiation time of the light will affect the structural stability and formation speed of the SiO2 passivation layer 500. Therefore, the light in this embodiment can prevent the hole transport layer 400 (functional film layer) and the SiO2 passivation layer 500 from excessive damage or thermal damage, avoid the slow formation speed of the SiO2 passivation layer 500, the failure of the precursor molecules to be fully excited, resulting in poor quality of the SiO2 passivation layer 500, and avoid the degradation of the internal materials and performance of the light-emitting device, that is, improve the stability and service life of the light-emitting device.

[0074] It is understood that the above light energy density can be 1mW / cm 2 、50mW / cm 2, 100mW / cm 2 、150mW / cm 2 , 200mW / cm 2 , 250mW / cm 2 、300mW / cm 2 、350mW / cm 2 , 400mW / cm 2 、450mW / cm 2 The wavelength may be 200nm, 250nm, 300nm, 350nm, or 380nm. The irradiation time may be 5min, 10min, 20min, 30min, 40min, 50min, 60min, 70min, 80min, 90min, or 100min, or a range formed by any two of the above values.

[0075] In some embodiments, before step 200, the following steps are also included: the base film includes a hole injection layer film, and the preparation step of the hole injection layer film is: coating the hole injection layer material on the substrate to form a hole injection layer film. The material of the hole injection layer film includes any one or a combination of nanoparticles of phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, CuSCN, nickel oxide, cuprous iodide, and MoO3-, V2O5 or WO3. At this time, the material of the hole injection layer 300 can assist with the material of the hole transport layer 400 to optimize the charge transfer and charge injection process, thereby improving the efficiency, stability and photoelectric conversion performance of the light-emitting device. At the same time, because the hole injection layer 300 uses the above-mentioned materials, it can avoid the effects of solvent penetration and adverse reactions on the hole injection layer when covering the mixed solution on the hole injection layer 300 and treating the mixed solution.

[0076] It can be understood that the step of coating the hole injection layer material on the substrate to form a hole injection layer film specifically includes: spin coating a 40nm to 60nm thick solution containing the hole injection layer material on the substrate, baking in an air atmosphere, the baking time is 100°C to 200°C, and the baking time is 15min to 25min, so that the hole injection layer material forms an oxide, thereby completing the preparation of the hole injection layer 300. The thickness of the solution containing the hole injection layer material can be 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, 52nm, 54nm, 56nm, 58nm, and 60nm, any one of which or a range formed by any two of the values; the baking time can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, and 200°C, any one of which or a range formed by any two of the values; the 15min to 25min should be understood to include but not be limited to the range formed by any one of which or any two of the values ​​of 15min, 17min, 19min, 21min, 23min, and 25min.

[0077] The embodiment of the present application also provides a light-emitting device, which is prepared by the above-mentioned method for preparing a functional film layer; the light-emitting device includes a stacked substrate 100, a bottom electrode, a hole injection layer 300, a hole transport layer 500, a light-emitting layer 600, an electron transport layer 700 and a top electrode. The bottom electrode can be an anode 200, and the top electrode can be a cathode 800. The hole functional layer includes a hole transport layer and a hole injection layer. The hole transport layer 400 and the light-emitting layer 600; the mixed solution includes a functional material precursor and a P-type doping material; wherein the functional material precursor and the P-type doping material form a mixed material body. The embodiment of the present application uses a functional material precursor and a P-type doping material to form a mixed material body, and precipitation, acidic oxidation and the like will not occur between the two materials. Therefore, the present embodiment can improve the conductivity of the hole transport layer 400 and balance the carriers, thereby reducing the driving voltage of the light-emitting device and improving the optical display effect of the light-emitting device.

[0078] It is understood that the light emitting device is a quantum dot light emitting diode or an organic light emitting diode. The light emitting device can be used in 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, wherein the smart wearable device can be, for example, a smart bracelet, a smart watch, a virtual reality (VR) helmet, etc. The light emitting device may also include an electrode 200 (anode), a hole injection layer 300 disposed between the electrode 200 and the hole transport layer 400, an electron transport layer 700 disposed on the side of the light emitting layer 600 away from the hole transport layer 400, and a cathode 800 disposed on the electron transport.

[0079] In some embodiments, the light-emitting device further includes a SiO2 passivation layer 500, which is disposed between the light-emitting layer 600 and the hole transport layer 400, and the thickness of the SiO2 passivation layer 500 includes 0.5nm to 3nm. The SiO2 passivation layer 500 can form an insulating layer between the light-emitting layer 600 and the hole transport layer 400, which can prevent the light-emitting layer from being quenched. At the same time, the SiO2 passivation layer 500 of the embodiment of the present application is relatively thin, which can prevent the excessively thick SiO2 passivation layer 500 from causing the conductivity of the excited light device to decrease, the current to decrease, and the driving voltage to increase. The thickness of the SiO2 passivation layer 500 can be any one of 0.5nm, 1.0nm, 1.5nm, 2.0nm, 2.5nm, 3.0nm, 3.5nm, 4.0nm, 4.5nm, and 5.0nm, or a range formed by any two of the values.

[0080] 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.

[0081] Example 1

[0082] The present invention provides a method for preparing a light-emitting device. The method is as follows:

[0083] Providing a substrate with an ITO anode, cleaning the substrate; treating the substrate under UV (ultraviolet) conditions for 15 minutes to increase the work function and wettability of the substrate;

[0084] Spin-coat 50 nm thick ammonium molybdate on the substrate and bake it in air at 150°C for 20 min to form a MoO3 hole injection layer;

[0085] A mixed solution (composition includes ethanol solvent, nickel acetylacetonate and phosphomolybdic acid in a mass ratio of 10:1) is spin-coated on the hole injection layer with a thickness of 30 nm, and the substrate is baked in air at a baking temperature of 250° C. for 30 min to form a hole transport layer;

[0086] After the substrate is cooled, the substrate is immersed in a silsesquioxane derivative solution (a 1 mol PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl aqueous solution) for 30 min, and then the substrate is washed with ethanol and subjected to light treatment in an ultraviolet ozone environment for 30 min to form a SiO2 passivation layer on the hole transport layer;

[0087] A 30nm thick green QDs functional ink was spin-coated on the SiO2 passivation layer and baked at 100℃ for 10min to form a light-emitting layer; a 30nm thick 5% Mg-doped ZnO was spin-coated and annealed at 80℃ for 10min to form an electron transport layer; a 100nm thick Al was vacuum evaporated and annealed at 100℃ for 30min to form a cathode.

[0088] Example 2

[0089] This embodiment is basically the same as the embodiment 1, except that the ratio of nickel acetylacetonate to phosphomolybdic acid is 50:1.

[0090] Example 3

[0091] This embodiment is basically the same as the embodiment 1, except that the ratio of nickel acetylacetonate to phosphomolybdic acid is 100:1.

[0092] Example 4

[0093] This embodiment is basically the same as the embodiment 1, except that the ratio of nickel acetylacetonate to phosphomolybdic acid is 1:1.

[0094] Example 5

[0095] This embodiment is basically the same as the embodiment 1, except that the ratio of nickel acetylacetonate to phosphomolybdic acid is 1:1.5.

[0096] Example 6

[0097] This embodiment is basically the same as the embodiment 1, except that the silsesquioxane derivative solution is PSS-octa[2-(p-carboxyphenyl)ethyl].

[0098] Example 7

[0099] This embodiment is substantially the same as Embodiment 1, except that the components of the mixed solution include an ethanol solvent, nickel chloride and phosphomolybdic acid in a mass ratio of 10:1.

[0100] Example 8

[0101] This embodiment is substantially the same as Embodiment 1, except that the components of the mixed solution include an ethanol solvent, nickel chloride and phosphotungstic acid in a mass ratio of 10:1.

[0102] Comparative Example 1

[0103] This comparative example is basically the same as Example 1, except that: the mixed solution is not doped with P-type doping material, and no SiO2 passivation layer is formed between the hole transport layer and the light-emitting layer.

[0104] Comparative Example 2

[0105] This comparative example is basically the same as Example 1, except that: the mixed solution is not doped with P-type doping material, and the silsesquioxane derivative solution is PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl

[0106] Comparative Example 3

[0107] This comparative example is basically the same as Example 1, except that the steps of forming the SiO2 passivation layer are not performed.

[0108] The performance of the light-emitting devices of Examples 1 to 6 and Comparative Examples 1 to 3 was tested using IVL equipment, with the voltage at a current density of 10 mA / cm2 (J10) being used as a driving voltage indicator, the current efficiency at a brightness of 1000 nit being used as a current efficiency indicator, and the time it takes for the brightness to decay to 95% from an initial brightness of 1000 nit under constant current conditions being used as a life evaluation indicator for the light-emitting device. The test results are shown in Table 1.

[0109] Table 1:

[0110]

[0111]

[0112] From Table 1, we can see that:

[0113] The hole transport layers of Examples 1 to 6 are doped with P-type doping materials, and their driving voltage is effectively reduced compared with the hole transport layer not doped with P-type doping materials (Comparative Example 1). According to the results of Examples 1 to 5, when the mass ratio of nickel acetylacetonate to phosphomolybdic acid in the mixed solution is 10:1, the driving voltage of the light-emitting device is the lowest, the current efficiency is the highest, and the device life is the longest.

[0114] According to Example 1 and Comparative Example 3, it can be seen that the SiO2 passivation layer can effectively improve the device life and current efficiency. According to Example 6 and Example 1, when the component of the silsesquioxane derivative solution is PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl, the current efficiency is the highest.

[0115] It can be seen from Example 1, Example 7 and Example 8 that the P-type doping materials involved in the present application can balance carriers, improve current efficiency and device life, and reduce driving voltage.

[0116] The functional film layer, its preparation method and the light-emitting device provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article 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 method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A functional film layer, characterized in that: The material of the functional film layer includes functional material and P-type doping material; Wherein, the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1 eV to 1 eV.

2. The functional film layer according to claim 1, characterized in that: The absolute value of the LUMO energy level of the P-type doping material is ≥5eV; and / or, The absolute value of the HOMO energy level of the functional material is 5.1 eV to 6 eV.

3. The functional film layer according to claim 1, characterized in that: The P-type doping material is at least one of Cu2O, CuSCN, MoO3, WoO3, NiO, CuO, and V2O5; and / or, The P-type doping material includes at least one of phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO3, V2O5 and WO3.

4. A method for preparing a functional film layer, characterized in that: The method comprises: Provide base film, functional material precursor, P-type doping material, and solvent; Mixing the functional material precursor, the P-type doping material, and the solvent to obtain a mixed solution; placing the mixed solution on the base film and performing a desolventizing treatment to obtain the functional film layer; The functional film layer includes a functional material transformed from the functional material precursor, and the difference between the absolute value of the HOMO energy level of the functional material and the absolute value of the LUMO energy level of the P-type doping material is 0.1 eV to 1 eV.

5. The method for preparing a functional film layer according to claim 4, characterized in that: The functional material precursor includes any one of doped or undoped metal oxides, doped or undoped metal sulfides, doped or undoped metal selenides or a combination thereof; and / or, The absolute value of the LUMO energy level of the P-type doping material is ≥5eV; and / or, The absolute value of the HOMO energy level of the functional material is 5.1 eV to 6 eV.

6. The method for preparing a functional film layer according to claim 4, characterized in that: Before the step of placing the mixed solution on the base film, the following steps are also included: The functional material precursor, the P-type doping material and the solvent are mixed to prepare the mixed solution, wherein the mass ratio of the functional material precursor to the P-type doping material is (50:1) to (1:1).

7. The method for preparing a functional film layer according to claim 6, characterized in that: The functional material precursor includes any one of nickel chloride, nickel acetylacetonate, nickel acetate, nickel nitrate, and nickel sulfate, or a combination thereof; And / or, the P-type doping material includes any one of phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, MoO3, V2O5 and WO3.

8. The method for preparing a functional film layer according to claim 6, characterized in that: The step of desolventizing comprises: The base film containing the mixed solution is placed in an oxygen-containing environment for baking treatment, the baking temperature is 200° C. to 250° C., and the solvent removal treatment time is 30 min to 60 min.

9. The method for preparing a functional film layer according to claim 4, characterized in that: After the step of obtaining the functional film layer, the following steps are also included: Immersing the functional film layer in a silsesquioxane derivative solution; The functional film layer is subjected to light treatment to form a SiO2 passivation layer on the surface of the functional film layer.

10. The method for preparing a functional film layer according to claim 9, characterized in that: The silsesquioxane derivative solution includes any one of PSS-[3-(2-aminoethyl)amino]propyl-substituted heptaisobutyl, PSS-octa[2-(p-carboxyphenyl)ethyl], octa[2-(4-carboxy-1,1-biphenyl)ethyl], PSS-(3-mercapto)propyl-heptaisobutyl or a combination thereof.

11. The method for preparing a functional film layer according to claim 9, characterized in that: The light energy density of the light treatment is 1mW / cm 2 ~500mW / cm 2 and / or, The wavelength of the light used in the illumination treatment is 200nm to 380nm; and / or, The light irradiation time of the light treatment is 5 minutes to 100 minutes.

12. The method for preparing a functional film layer according to claim 4, characterized in that: The base film includes a hole injection layer film, and the material of the hole injection layer film includes any one or a combination of phosphomolybdic acid, phosphotungstic acid, ammonium metatungstate, ammonium metavanadate, ammonium molybdate, CuSCN, nickel oxide, cuprous iodide, and nanoparticles of MoO3, V2O5 or WO3.

13. A light emitting device, characterized in that: The light-emitting device comprises a bottom electrode, a hole functional layer, a light-emitting layer, an electron functional layer, and a top electrode; Wherein, the hole functional layer is the functional film layer described in claims 1 to 3 above, or is prepared by the preparation method of the functional film layer according to any one of claims 4 to 12 above.

14. The light emitting device according to claim 13, characterized in that: The light emitting device further comprises a light emitting layer and a SiO2 passivation layer, wherein the SiO2 passivation layer is arranged between the light emitting layer and the hole transport layer, and the thickness of the SiO2 passivation layer is 0.5 nm to 3 nm.

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