Thin film and preparation method thereof, photoelectric device and display device

Abstract

The invention discloses a thin film and a preparation method thereof, a photoelectric device and a display device, the material of the thin film comprises an N-type inorganic semiconductor or a P-type inorganic semiconductor, and a plurality of holes are formed in the thin film. According to the thin film provided by the technical scheme of the invention, a porous structure is formed, and the charge transfer capability of the thin film can be adjusted to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a thin film and a preparation method thereof, an optoelectronic device and a display device. BACKGROUND

[0002] Semiconductor material is a kind of electronic material with semiconductor performance, which can be used to make semiconductor devices and integrated circuits. Thin films made of semiconductor materials are widely used in the field of optoelectronic technology. SUMMARY

[0003] Therefore, the present application provides a thin film and a preparation method thereof, an optoelectronic device and a display device.

[0004] The present application is implemented as follows:

[0005] In a first aspect, the present application provides a thin film, wherein the material of the thin film comprises an N-type inorganic semiconductor or a P-type inorganic semiconductor, and the thin film is formed with a plurality of pores.

[0006] In a second aspect, the present application provides a preparation method of a thin film, comprising the following steps:

[0007] providing a mixed solution containing a host material, an additive and a solvent;

[0008] after depositing the mixed solution, performing a first heat treatment in a first humidity environment to obtain a thin film;

[0009] wherein the host material comprises any one of an N-type inorganic semiconductor and a P-type inorganic semiconductor, and the additive comprises one or more of urea and ammonium salt.

[0010] In a third aspect, the present application provides an optoelectronic device, comprising a stacked anode, one or more functional layers and a cathode, wherein the one or more functional layers comprise one or more of a hole functional layer and an electron functional layer, one of the hole functional layer or the electron functional layer comprises the thin film or the thin film prepared by the preparation method; when the electron functional layer comprises the thin film, the material of the electron functional layer comprises the N-type inorganic semiconductor, and when the hole functional layer comprises the thin film, the material of the hole functional layer comprises the P-type inorganic semiconductor.

[0011] In a fourth aspect, the present application provides a display device comprising the optoelectronic device.

[0012] The thin film provided by the technical scheme of the present application is formed with a porous structure, and the charge transport capability thereof can be adjusted to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on these drawings also belong to the protection scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain and illustrate the present application, and should not be used to limit the present application. In the present application, the orientation words such as "upper" and "lower" are the directions of the drawing surface. In addition, in the description of the present application, the term "comprising" means "comprising but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit to the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers in the range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in the present application, it means that any quoted number (fraction or integer) in the indicated range is included.

[0014] Figure 1 is a flowchart of a method for preparing a thin film according to an embodiment of the present application;

[0015] Figure 2 is a schematic diagram of a structure of an optoelectronic device according to an embodiment of the present application;

[0016] The drawings are as follows: optoelectronic device 100; anode 10; cathode 20; electron transport layer 30; light emitting layer 40, hole injection layer 50, hole transport layer 60. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain and illustrate the present application, and should not be used to limit the present application. In the present application, the orientation words such as "upper" and "lower" are the directions of the drawing surface. In addition, in the description of the present application, the term "comprising" means "comprising but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit to the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers in the range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in the present application, it means that any quoted number (fraction or integer) in the indicated range is included.

[0018] In the present application, the association relationship of the associated objects is described as "and / or", which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following cases: only A exists, A and B exist at the same time, and only B exists. Wherein A and B can be singular or plural.

[0019] In this application, "at least one" means one or more, and "more than one" 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 or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0020] In a first aspect, embodiments of this application propose a thin film, the material of which includes an N-type inorganic semiconductor or a P-type inorganic semiconductor, and the thin film having a plurality of pores.

[0021] The pores can be distributed on the surface of the film, inside the film, or both. This application does not limit their specific distribution location.

[0022] The thin film provided by this application has a porous structure inside, which can reduce its charge transport capability to a certain extent and can be applied to application scenarios that require thin films with different charge transport capabilities.

[0023] Depending on the materials used in the thin film, the resulting thin film has different properties, thus allowing it to be applied in different directions.

[0024] When the material is an N-type inorganic semiconductor, it possesses electron transport or electron injection properties. Correspondingly, the resulting thin film also possesses electron transport or electron injection properties and can be used to fabricate the electronic functional layer of an optoelectronic device 100. In some embodiments, the N-type inorganic semiconductor may include, but is not limited to, at least one of metal oxides and doped metal oxides. The metal oxides include at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3. The doped metal oxides include at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3. The doping element includes at least one of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, B, Ca, Cu, Zn, and F. Its molecular formula can be expressed as Q. 1-y E y O, where Q is selected from one of Zn, Ti, Sn, Ga, and Al, and E is selected from one or more of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, B, Ca, Cu, Zn, and F. Q and E are not the same, and 0.5 ≥ y > 0.

[0025] In some embodiments, the average particle size of the N-type inorganic semiconductor is 3–8 nm; for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, or any range between two of the above values. In this document, the average particle size can be obtained by measuring the sample using a transmission electron microscope (TEM) at an accelerating voltage of 100 kV.

[0026] N-type inorganic semiconductors, such as metal oxides or doped metal oxides, possess excellent electron transport properties and high electron mobility. However, their compatibility with current mainstream light-emitting layer materials and organic hole transport materials is poor, easily leading to carrier imbalance within the device and resulting in a shorter device lifetime. The thin film with N-type inorganic semiconductors as the main material provided in this application has a porous internal structure, which can adjust the electron transport capability to a certain extent, avoiding the carrier imbalance problem caused by excessive electrons and extending the device's lifespan.

[0027] The thin film with N-type inorganic semiconductor as the main material provided in this application has an electron mobility of 10. -3 ~1cm 2 / (V·s).

[0028] When the material is a P-type inorganic semiconductor, it possesses hole transport or hole injection properties. Correspondingly, the resulting thin film also possesses hole transport or hole injection properties and can be used to fabricate the hole functional layer of the optoelectronic device 100. The hole functional layer includes one or both of a hole transport layer 60 and a hole injection layer 50. In some embodiments, the P-type inorganic semiconductor includes at least one of nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0029] In some embodiments, the average particle size of the P-type inorganic semiconductor is 3 to 8 nm; for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, or any two of the above values.

[0030] In some devices, there may be a problem where hole injection is greater than electron injection. For such devices, this application introduces a thin film with P-type inorganic semiconductor as the main material, which has a porous structure inside. This can reduce the hole transport capacity to a certain extent, avoid the problem of device carrier imbalance caused by excessive holes, and extend the device life.

[0031] The hole mobility of the thin film with P-type inorganic semiconductor as the main material provided in this application is 10. -5 ~10 -2 cm 2 / (V·s).

[0032] In some embodiments, the thin film contains hydroxyl groups dispersed on the surface of an N-type or P-type inorganic semiconductor. For example, some hydroxyl groups may be connected to the N-type or P-type inorganic semiconductor. Uncoordinated metal atoms exist on the surface of the N-type or P-type inorganic semiconductor, and the hydroxyl groups can connect to these metal atoms. When the thin film is used as a functional layer of an optoelectronic device 100, the introduction of hydroxyl groups that can react with the metal electrode interface facilitates the formation of a stable interface and improves device stability. In some cases, the thin film is prepared using solution-based processes such as inkjet printing. When high-boiling-point solvents are used, the coordination of these solvents may alter the surface state of the material and the stability of its interface with the electrode, thereby affecting device performance. The thin film proposed in this application, by introducing active hydroxyl groups, can promote the recovery of the performance of the ink film after deposition, reducing the adverse effects of high-boiling-point solvents. This helps reduce the difficulty of solvent selection, thereby expanding the range of compatible solvents and reducing the difficulty of ink optimization.

[0033] In some embodiments, the mass percentage of hydroxyl groups in the film is 5% to 25%; for example, it can be 5%, 8%, 10%, 13%, 15%, 18%, 20%, 22%, 25%, or any two of the above values. It is understood that the mass percentage of hydroxyl groups refers to the percentage of the mass of hydroxyl groups in the film relative to the total mass of the film. In actual testing, thermogravimetric analysis (TGA), a commonly used method in the art, can be used. For example, the film can be heated by a programmed temperature increase, and the change in film mass during temperature changes can be analyzed. The mass of the film before and after hydroxyl group detachment is recorded, and the percentage of the mass difference relative to the initial mass of the film before weight loss is the mass percentage of hydroxyl groups. Specifically, the temperature range of the programmed temperature increase can be from room temperature (20–40°C) to 700°C. In some embodiments, the temperature range in which hydroxyl groups detach is approximately in the range of 100–270°C.

[0034] In some embodiments, the porosity of the thin film is 8.5% to 50%; for example, it can be 8.5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range between two of the above values. The porosity refers to the percentage of pore volume in the thin film. The porosity can be tested using the BET test method (specific surface area measurement method). By adjusting the porosity of the thin film, it is helpful to precisely control the charge transport capability of the thin film, enabling it to have suitable electron / hole mobility.

[0035] In some embodiments, the average pore size of the pores in the thin film is 3–15 nm; for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or any range between two of the above values. The average pore size can be tested using the BET test method.

[0036] In some embodiments, the surface roughness Rq of the thin film is 3–10 nm; for example, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, and any two of the above values. The surface roughness Rq refers to the root mean square surface roughness, which can be measured by atomic force microscopy (AFM).

[0037] The thin film can take many forms. For example, in some embodiments, the thin film may include a first thin film with a porosity in the range of 20% to 50%, exhibiting a relatively large pore structure and having a relatively low electron / hole mobility.

[0038] In the first thin film, the average pore size is 10–15 nm; for example, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, and any two of the above values. The average pore size can be tested using the BET test method.

[0039] The surface roughness Rq1 of the first thin film is 7–10 nm; for example, 7 nm, 8 nm, 9 nm, 10 nm, and any two of the above values. The surface roughness Rq1 refers to the root mean square surface roughness, which can be measured by atomic force microscopy (AFM).

[0040] In other embodiments, the thin film may include a second thin film, the material of which further includes a dopant material, and the porosity of the second thin film is 8.5% to 20%. The porosity of the second thin film is lower than that of the first thin film, but at least one of the pores in the second thin film is filled with a dopant material. By filling with a dopant material, the energy levels and conductivity of the thin film can be further fine-tuned to obtain more suitable electrical properties.

[0041] In the second thin film, the average pore size is 3–7 nm; for example, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, or any two of the above values. The average pore size can be tested using the BET test method.

[0042] The surface roughness Rq2 of the second thin film is 3–6 nm; for example, 3 nm, 4 nm, 5 nm, 6 nm, and any two of the above values. The surface roughness Rq1 refers to the root mean square surface roughness, which can be tested by AFM.

[0043] The doping material may include, but is not limited to, one or more of metal oxides, metal halide salts, metal carbonates, and metal sulfates. The surface of the doping material has defects, such as anion vacancies or cation vacancies, which can bond with defects on the surface of N-type or P-type inorganic semiconductors, achieving connection. In some embodiments, the metal ions in the doping material can connect with oxygen atoms in the N-type or P-type inorganic semiconductor. By filling a porous film with doping material, not only can the energy levels and conductivity of the film be controlled, but it also helps to effectively increase and precisely control the doping amount. In other embodiments, hydroxyl groups may also connect with the doping material during the doping process; for example, hydroxyl groups may connect with uncoordinated metal atoms on the surface of the doping material.

[0044] In some embodiments, the molar amount of metal atoms (referring to metal atoms in the doped material) in the thin film can reach 18% to 50% of the total molar amount of metal atoms and inorganic semiconductors. By flexibly controlling the doping amount and the type of doping material, precise control of energy levels and conductivity can be effectively achieved. For example, doping ZnO with aluminum (Al), silver (Ag), indium (In), tungsten (W), molybdenum (Mo), tin (Sn), vanadium (V), iron (Fe), etc., can promote electron injection; doping with magnesium (Mg), cobalt (Co), boron (B), calcium (Ca), copper (Cu), zinc (Zn), fluorine (F), etc., can reduce electron injection. In some embodiments, the metal element in the metal oxide, the metal element in the metal halide, the metal element in the metal carbonate, and the metal element in the metal sulfate are each independently selected from one or more of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, Ca, Cu, and Zn.

[0045] In some embodiments, the doped material can be deposited on a thin film using a physical vapor deposition method; for example, it can be achieved through methods such as evaporation, sputtering, ion implantation, plasma vapor deposition, and ion irradiation. Specifically, the metal oxide can be doped by evaporation or sputtering of elemental metals or metal oxides, the metal halide can be doped by sputtering, ion implantation, or plasma vapor deposition, and the metal carbonate and metal sulfate can be doped by ion implantation or plasma vapor deposition.

[0046] Secondly, this application also proposes a method for preparing a thin film; please refer to [link to relevant documentation]. Figure 1The preparation method includes the following steps:

[0047] S10 provides a mixed solution containing a main material, additives, and solvent;

[0048] S20, after depositing the mixed solution, a first heat treatment is performed under a first humidity environment to obtain a thin film;

[0049] The main material includes any one of N-type inorganic semiconductors and P-type inorganic semiconductors, and the additives include one or more of urea and ammonium salts.

[0050] The ammonium salt may include, but is not limited to, one or more of ammonium halides, ammonium carbonate, ammonium nitrate, ammonium bicarbonate, ammonium citrate, ammonium acetate, ammonium sulfate, and ammonium phosphate. The ammonium halides include one or more of ammonium fluoride, ammonium chloride, ammonium bromide, and ammonium iodide.

[0051] The first heat treatment is carried out under a first humidity environment, which refers to an environment containing water vapor. During the first heat treatment, the additive reacts with water and decomposes. The decomposition products can, on the one hand, form hydroxyl groups that adsorb onto the surface of the host material, promoting the interfacial reaction between the thin film and the metal electrode and improving interfacial stability; on the other hand, they can also generate gas. This gas can help form a thin film with multiple pores, which can reduce the conductivity of the film layer. For example, when the additive is urea, under a thermal environment, urea and water can react to produce carbon dioxide and ammonia. When the additive is an ammonium salt, it can also react to produce carbon dioxide, ammonia, and other products.

[0052] To better control the porosity of the film, the amount of additive can be adjusted. In some embodiments, the mass ratio of the additive to the main material is 1:4 to 20; for example, it can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, or any range between any two of the above values.

[0053] In other embodiments, the concentration of the additive in the mixed solution is 0.5–5 mg / mL; for example, it can be 0.5 mg / mL, 0.6 mg / mL, 0.7 mg / mL, 0.8 mg / mL, 0.9 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, and any range between two of the above values.

[0054] The solvent includes at least one of C1-C7 straight-chain alcohols, C2-C4 polyols, C2-C6 alcohol ether compounds, and polyethylene glycol. The C1-C7 straight-chain alcohols include one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol. The C2-C6 alcohol ether compounds include one or more of ethylene glycol monobutyl ether and methoxybutanol. The C2-C4 polyols include one or more of glycerol, ethylene glycol, diethylene glycol, dipropylene glycol, and glycerol.

[0055] The temperature of the first heat treatment is 100 to 140°C; for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C, or any two of the above values. Controlling it within this range can accelerate the decomposition of additives and ensure the crystallinity of the film itself, which is beneficial for the formation of a porous network.

[0056] The time for the first heat treatment is 2 to 30 minutes; for example, it can be 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or any two of the above values.

[0057] In some embodiments, the humidity of the first humidity environment is 10% to 50%. For example, it can be 10%, 20%, 30%, 40%, 50%, or any two of the above values. Controlling it within this range can provide a suitable reaction environment for the decomposition of additives and prevent the film from being eroded.

[0058] In some embodiments, the first heat treatment step may be performed under an inert atmosphere, which may include, but is not limited to, one or more of nitrogen, helium, and argon.

[0059] In some embodiments, the deposition of the mixed solution can be carried out by various methods such as spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating. After the liquid film is deposited, the solvent-formed film layer can be removed by allowing it to stand in a vacuum environment, and then the film layer can be subjected to a subsequent first heat treatment.

[0060] The thin film can be a first thin film or a second thin film. Based on this, in some embodiments, step S20 may specifically include: depositing the mixed solution, and then performing a first heat treatment under a first humidity environment to obtain a first thin film with multiple pores. In other embodiments, step S20 may specifically include: depositing the mixed solution, and then performing a first heat treatment under a first humidity environment to obtain a first thin film with multiple pores; providing a dopant material source, placing the dopant material source on the first thin film, and then performing a second heat treatment to obtain a second thin film doped with the dopant material; wherein, in the second thin film, at least one of the pores is filled with the dopant material, the dopant material is connected to the N-type inorganic semiconductor or the P-type inorganic semiconductor, and the dopant material includes one or more of metal oxides, metal halide salts, metal carbonates, and metal sulfates. By placing the dopant source on the first thin film and contacting the dopant source with the first thin film having a porous structure, the dopant material can be filled into the pores of the first thin film, and the energy level and conductivity of the thin film can be flexibly controlled to obtain a second thin film. On this basis, further heat treatment of the thin film can also promote ion rearrangement and bonding in the porous film layer, induce solid-phase reaction of dissolution and recrystallization in the porous film layer, promote doping uniformity and film layer stability, and improve the film formation effect.

[0061] In some embodiments, the porosity of the first film is greater than or equal to the porosity of the film doped with metal atoms.

[0062] In some embodiments, the porosity of the first film is 20-50%.

[0063] In some embodiments, the porosity of the second film is 8.5 to 20%.

[0064] Metal oxides are typically prepared using solution precipitation. Elemental doping usually involves adding a dopant source to the reaction solution during oxide synthesis. However, this doping process is not highly controllable; the content and type of doped elements are often limited by ion size, solvent, and salt composition. Doping concentrations are typically low, and the resulting side reaction impurities are difficult to remove during cleaning, thus affecting device performance. For example, in some cases, the doping concentration of Mg in ZnO can reach up to that of Zn. 0.85 Mg 0.15However, further increasing the amount of magnesium source can easily lead to problems such as solution turbidity and difficulty in separation. Furthermore, if a doping process involving first preparing a ZnO thin film and then depositing Mg onto it is used, most of the Mg will deposit as elemental on the film surface, resulting in a low effective doping level for the ZnO film. Additionally, the elemental Mg layer is easily oxidized to form an insulating oxide film, which negatively impacts device performance. In this application, a porous first thin film is formed first, followed by elemental doping. These pores provide space for the doped material, improving doping efficiency and effective doping level, allowing the doping level γ to reach 0.50.

[0065] In some embodiments, the temperature of the second heat treatment is 60 to 120°C; for example, it can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any two of the above values. This can promote the continued dissolution and recrystallization of the porous film, thereby reducing its porosity to a certain extent and forming a doped dense film.

[0066] The second heat treatment time is 5 to 60 minutes; for example, it can be 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or any two of the above values.

[0067] The second heat treatment is carried out in a second humidity environment, the humidity of which is 10% to 50%. For example, it can be 10%, 20%, 30%, 40%, 50%, or any two of the above values. Controlling the humidity within this range can provide a suitable reaction environment for the dissolution and recrystallization process, introduce hydroxyl ligands, and at the same time avoid introducing too many quenching centers.

[0068] In some embodiments, the second heat treatment step may be carried out under an inert atmosphere, which may include, but is not limited to, one or more of nitrogen, helium, and argon.

[0069] The doping material source includes one or more of elemental E and E-containing compounds, wherein the E-containing compounds include one or more of E-containing oxides, E-containing halide salts, E-containing sulfates, and E-containing carbonates, and E is selected from at least one of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, Ca, Cu, and Zn.

[0070] In some embodiments, the step of disposing of the dopant material source on the first thin film includes: depositing the dopant material source on the first thin film by physical vapor deposition. The physical vapor deposition method may be evaporation, sputtering, ion irradiation, ion implantation, plasma vapor deposition, etc.

[0071] Thirdly, this application also proposes a composition comprising a host material, additives, and a solvent. The host material comprises any one of N-type and P-type inorganic semiconductors, and the additives comprise one or more of urea and ammonium salts. The composition can be used to fabricate thin films. Specifically, after depositing the composition to form a liquid film, a first heat treatment is performed to obtain a thin film with multiple pores inside. For details, please refer to the embodiments of the above-described thin film preparation method, which will not be elaborated here. The thin film thus formed has a porous structure, which can reduce its charge transport capability to a certain extent. It is suitable for applications requiring thin films with different charge transport capabilities. Furthermore, depending on the semiconductor material in the thin film, the resulting thin film can have different properties, thus allowing it to be applied to different film layers of the optoelectronic device 100.

[0072] In some embodiments, the concentration of the additive in the composition is 0.5 to 5 mg / mL; for example, it can be 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, and any range between two of the above values.

[0073] The solvent includes at least one of C1-C7 straight-chain alcohols, C2-C4 polyols, C2-C6 alcohol ether compounds, and polyethylene glycol. The C1-C7 straight-chain alcohols include one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol. The C2-C6 alcohol ether compounds include one or more of ethylene glycol monobutyl ether and methoxybutanol. The C2-C4 polyols include one or more of glycerol, ethylene glycol, diethylene glycol, dipropylene glycol, and glycerol.

[0074] In the composition, the mass ratio of the additive to the main material is 1:4 to 20; for example, it can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, and any range between any two of the above values.

[0075] The ammonium salt may include, but is not limited to, one or more of ammonium halides, ammonium carbonate, ammonium nitrate, ammonium bicarbonate, ammonium citrate, ammonium acetate, ammonium sulfate, and ammonium phosphate. The ammonium halides include one or more of ammonium fluoride, ammonium chloride, ammonium bromide, and ammonium iodide.

[0076] Fourthly, this application also proposes an optoelectronic device 100, including but not limited to organic light-emitting diodes, quantum dot light-emitting diodes, photovoltaic cells, and photodetectors. The optoelectronic device 100 can be a positively oriented device or an inverted device. Please refer to [link to relevant documentation]. Figure 2 The optoelectronic device 100 includes a stacked anode 10, one or more functional layers, and a cathode 20. At least one of the functional layers includes one or more hole functional layers and electron functional layers. One of the hole functional layers and the electron functional layer comprises the thin film described above, or a thin film prepared by the preparation method described above, or a thin film prepared from the composition described above. The material of the electron functional layer includes the N-type inorganic semiconductor, and the material of the hole functional layer includes the P-type inorganic semiconductor. In other words, at least one functional layer in the optoelectronic device 100 uses a thin film containing an N-type inorganic semiconductor and having a plurality of pores as the electron functional layer, or at least one functional layer uses a thin film containing a P-type inorganic semiconductor and having a plurality of pores as the hole functional layer.

[0077] The thin film has adjustable charge transport capability, which can meet the needs of optoelectronic devices 100 with different film layer requirements. It can be matched with other film layer structures more flexibly to construct devices with better carrier balance and stability, so that the devices have high luminous efficiency and long lifetime.

[0078] In addition to the anode 10 and cathode 20, the optoelectronic device 100 may also have other functional layers, such as including but not limited to a hole functional layer, an electron functional layer, and a light-emitting layer 40. The hole functional layer includes one or both of a hole injection layer 50 and a hole transport layer 60, and the electron functional layer includes one or both of an electron injection layer and an electron transport layer 30. When the one or more functional layers are composed of a hole transport layer 60, a hole injection layer 50, an electron transport layer 30, and an electron injection layer, and the optoelectronic device 100 also includes a light-emitting layer 40, the film structure of the optoelectronic device 100 is as follows: the anode 10, hole injection layer 50, hole transport layer 60, light-emitting layer 40, electron transport layer 30, electron injection layer, and cathode 20 are stacked sequentially; or, the cathode 20, electron injection layer, electron transport layer 30, light-emitting layer 40, hole transport layer 60, hole injection layer 50, and anode 10 are stacked sequentially. It is understood that when one or more of the above-mentioned functional layers are omitted, the remaining layers are still arranged in the above-mentioned stacking order. For example, when the optoelectronic device 100 does not include the electron transport layer 30 and the electron injection layer, the remaining layers are stacked in the following order: anode 10, hole injection layer 50, hole transport layer 60, light-emitting layer 40, and cathode 20 are stacked in sequence, or cathode 20, light-emitting layer 40, hole transport layer 60, hole injection layer 50, and anode 10 are stacked in sequence.

[0079] To improve the luminous efficiency and lifetime of the optoelectronic device 100, at least one of these film structures can be selected from the aforementioned thin films. For example, the aforementioned thin film with P-type inorganic semiconductor as the main material can be used as the hole functional layer, and the aforementioned thin film with N-type inorganic semiconductor as the main material can be used as the electron functional layer. For ease of description, such film layers using the aforementioned thin films are referred to as porous film layers. It is understood that, in addition to porous film layers, some functional layers may not use the aforementioned thin films. For such functional layers, the film layers can be prepared using conventional preparation methods in the art, and the film layer materials can also be commonly used film layer materials in the art. For example, in some embodiments, the hole functional layer is a porous film layer, and the electronic functional layer is prepared using conventional preparation methods in the art. The material of the electronic functional layer can be the electron injection material or electron transport material commonly used in optoelectronic devices 100 in the art. The electron transport material can include, but is not limited to, the above-mentioned N-type inorganic semiconductor, and the electron injection material can include, but is not limited to, at least one of LiF, MgP, MgF2, Al2O3, Ga2O3, LiF / Yb, ZnO, Cs2CO3, RbBr, and Rb2CO3.In other embodiments, the electronic functional layer is a porous film layer, and the hole functional layer is prepared using conventional methods in the art. The material of this hole functional layer can be a hole injection material or a hole transport material commonly used in optoelectronic devices. The hole transport material can include, but is not limited to, 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)](TFB), and 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), N,N'-Bis(3-methylphenyl)-N,N'-Bis(phenyl)-spiro(spiro-TPD), N,N'-Di(4-(N,N'-diphenyl-amino)phenyl)-N,N'-Diphenylbenzidine (DNTPD), Tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), Poly(p-)phenylethyleneethylene (PPV) ), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MOMO-PPV), 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS, poly(N-vinylcarbazole) (PVK), polymethacrylate, poly(9,9-octylfluorene), N,N'-di(naphthyl-1-yl)-N One or more of N'-diphenylbenzidine (NPB) and spiroNPB; the hole injection material may include, but is not limited to, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethyl ether, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0080] In some embodiments, the optoelectronic device 100 includes a light-emitting layer 40 disposed between the hole functional layer and the cathode 20, or between the electron functional layer and the anode 10. The material of the light-emitting layer 40 includes one or more of organic light-emitting materials and quantum dot light-emitting materials. The organic light-emitting materials include one or more of 4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III), 4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium(III), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescence materials, TTA materials, thermally activated delayed materials, polymers containing BN covalent bonds, hybrid localized charge transfer excited-state materials, and excitocomplex light-emitting materials.The quantum dot luminescent material comprises at least one of a single-structure quantum dot, a core-shell quantum dot, and a perovskite semiconductor material. The shell of the core-shell quantum dot comprises one or more layers. The material of the single-structure quantum dot, the core material of the core-shell quantum dot, and the shell material of the core-shell quantum dot each comprise at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds. The group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, and Cd. At least one of the following: SeS, 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 include SnS, SnS At least one of e, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the III-V compound includes at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNA. At least one of the following: s, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the group I-III-VI compounds include at least one of CuInS2, CuInSe2, and AgInS2.As an example, the core-shell structured quantum dots may be selected from, but are not limited to, at least one of CdZnSe / CdZnSe / ZnSe / CdZnS / ZnS, CdZnSe / CdZnSe / CdZnS / ZnS, CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS. It should be noted that for the aforementioned materials of single-structure quantum dots, or materials of the core of core-shell quantum dots, or materials of the shell of core-shell quantum dots, the provided chemical formulas only indicate the elemental composition, not the content of each element. For example, CdZnSe only indicates that it is composed of three elements: Cd, Zn, and Se. If the content of each element were indicated, it would correspond to Cd. x Zn 1-x Se, 0 <x<1。

[0081] The perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs. + Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is RMX3, wherein R is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of them.

[0082] The anode 10 and the cathode 20 are each independently selected from doped metal oxide particle electrodes, metal-metal oxide composite electrodes, graphene electrodes, carbon nanotube electrodes, metal electrodes, or alloy electrodes. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, and ITO / Ag. The metal electrode material is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba; where " / " indicates a stacked structure. For example, the composite electrode AZO / Ag / AZO represents a three-layer stacked composite structure consisting of an AZO layer, an Ag layer, and an AZO layer.

[0083] It is understood that the optoelectronic device 100 may also be provided with some functional layers that are conventionally used in optoelectronic devices 100 and help to improve the performance of optoelectronic devices 100, such as electron blocking layer, hole blocking layer, interface modification layer, etc.

[0084] It is understood that the materials of each layer of the optoelectronic device 100 can be adjusted according to the actual needs of the optoelectronic device 100.

[0085] It is understood that the optoelectronic device 100 may further include an encapsulation layer (not shown) to isolate water and oxygen (e.g., to reduce the concentration of oxygen and water to below 0.1 ppm), thereby improving the performance stability of the optoelectronic device 100. Specifically, the encapsulation material used to form the encapsulation layer may be selected from at least one of UV adhesive, metal film, and glass adhesive. In one specific embodiment, the encapsulation material may be acrylic resin or epoxy resin.

[0086] Based on the aforementioned optoelectronic device 100, a method for fabricating the optoelectronic device 100 is further proposed. The fabrication method includes: sequentially fabricating multiple film layers according to a predetermined film layer order to obtain the optoelectronic device 100; wherein the multiple film layers include an anode 10, a cathode 20, and one or more functional layers; when fabricating one or more functional layers, at least one of the functional layers is fabricated using the aforementioned thin film fabrication method. The predetermined film layer order refers to the order in which the optoelectronic device 100 is stacked from bottom to top.

[0087] The methods for forming the various film layers can be chemical or physical. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include physical deposition or solution processing. Physical deposition methods include thermal evaporation deposition (CVD), electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition (PVD), atomic layer deposition, and pulsed laser deposition. Solution processing methods include spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating. Those skilled in the art can prepare the various film layers of the optoelectronic device 100 of this application embodiment according to the known methods for preparing optoelectronic devices 100, which will not be elaborated further here.

[0088] Fourthly, this application also relates to a display device, which includes the optoelectronic device 100 provided in this application. The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0089] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0090] Thin Film Example 1

[0091] (1) Disperse ZnO and urea in ethanol to form a mixed solution. The mass ratio of ZnO to urea in the solution is 20:1, the concentration of ZnO is 20 mg / mL, and the concentration of urea is 1 mg / mL.

[0092] (2) Take a glass substrate, drop the mixed solution onto the substrate, spin coat at 4000 rpm for 30s, let it stand in a vacuum environment to form a solid film, and then heat at 120°C for 5min in a nitrogen atmosphere with a humidity of 30% to obtain a ZnO thin film with a thickness of 35nm.

[0093] Thin Film Example 2

[0094] The scheme in this embodiment is basically the same as that in embodiment 1, except that step (3) is also included in this embodiment:

[0095] Step (3): Place the semi-finished film prepared in step (2) into a vacuum coating machine and evacuate the vacuum to 3×10. - 4 Mg was deposited at a rate of 0.1 Å / s for 300 s using mbar, followed by heating at 80 °C for 10 min in a nitrogen atmosphere with 30% humidity to obtain a thin film filled with MgO in the pores. The molar ratio of Mg to Zn in the film was y:1-y.

[0096] Thin Film Example 3

[0097] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0098] In step (2), the humidity is 10%.

[0099] Thin Film Example 4

[0100] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0101] In step (2), the humidity is 50%.

[0102] Thin Film Example 5

[0103] The scheme in this embodiment is basically the same as that in embodiment 2, except that in this embodiment:

[0104] In step (2), the humidity is 55%.

[0105] Thin Film Example 6

[0106] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0107] In step (2), the temperature is 100℃.

[0108] Thin Film Example 7

[0109] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0110] In step (2), the temperature is 140℃.

[0111] Thin Film Example 8

[0112] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0113] In step (2), the temperature is 75℃.

[0114] Thin Film Example 9

[0115] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0116] In step (2), the temperature is 150℃.

[0117] Thin Film Example 10

[0118] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0119] In step (1), urea is replaced with ammonium chloride.

[0120] Thin Film Example 11

[0121] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0122] In step (1), urea is replaced with ammonium bicarbonate.

[0123] Thin Film Example 12

[0124] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0125] In step (1), the mass ratio of ZnO to urea is 15:1, and the corresponding concentration of urea is 1.33 mg / mL.

[0126] Thin Film Example 13

[0127] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0128] In step (1), the mass ratio of ZnO to urea is 4:1, and the corresponding concentration of urea is 6.25 mg / mL.

[0129] Thin Film Example 14

[0130] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0131] In step (3), the humidity is 10%.

[0132] Thin Film Example 15

[0133] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0134] In step (3), the humidity is 50%.

[0135] Thin Film Example 16

[0136] The scheme in this embodiment is basically the same as that in embodiment 2, the only difference being that in this embodiment:

[0137] In step (3), the humidity is 60%.

[0138] Thin Film Example 17

[0139] The scheme in this embodiment is basically the same as that in embodiment 2, except that in this embodiment, step (3) is changed to:

[0140] The semi-finished film prepared in step (2) was placed in a sputtering chamber and sputtered with MgF2 using magnetron sputtering. The sputtering conditions were set as follows: vacuum degree of 0.01 Pa, argon partial pressure of 1 Pa, sputtering voltage of 600 V (frequency of 13.56 MHz), sputtering current of 0.2 A, sputtering power of 100 W, self-bias voltage of -720 V, average deposition rate of film of approximately 0.25 nm / s, and sputtering time of 30 s. Subsequently, the film was heated at 80 °C for 10 min in a nitrogen atmosphere with 30% humidity to obtain a film with MgF2 filling the pores. The molar ratio of Mg to Zn in the film was y:1-y.

[0141] Thin Film Example 18

[0142] The scheme in this embodiment is basically the same as that in embodiment 1, except that in this embodiment:

[0143] In step (1), ZnO is replaced with NiO and the solvent is replaced with chlorobenzene.

[0144] Thin Film Comparative Example 1

[0145] This comparative example is basically the same as Example 1, except that the preparation method of this comparative example is as follows:

[0146] Remove urea in step (1);

[0147] Step (2) is changed to: take a glass substrate, drop the mixed solution onto the substrate, spin coat at 4000 rpm for 30s, and let it stand in a vacuum environment to remove the solvent, and obtain a ZnO film with a thickness of 35nm.

[0148] Thin Film Comparative Example 2

[0149] This comparative example is basically the same as Example 2, except that the preparation method of this comparative example is changed to:

[0150] (1) Disperse ZnO in ethanol to form a mixed solution. The concentration of ZnO in the solution is 20 mg / mL.

[0151] (2) Take a glass substrate, drop the mixed solution onto the substrate, spin coat at 4000 rpm for 30s, and let it stand in a vacuum environment to remove the solvent, and obtain a ZnO film with a thickness of 35 nm.

[0152] (3) Place the semi-finished film prepared in step (2) into a vacuum coating machine and evacuate the vacuum to 3×10⁻⁶. -4 Mg was deposited at a rate of 0.1 Å / s for 300 s using mbar, followed by heating at 80 °C for 10 min in a nitrogen atmosphere with 30% humidity to obtain a MgO-doped film.

[0153] Thin Film Comparative Example 3

[0154] This comparative example is basically the same as Example 18, except that urea is removed in step (1) of this comparative example.

[0155] Device Example 1

[0156] The device structure is ITO / PEDOT:PSS(20nm) / TFB(25nm) / QD(30nm) / ETL(35nm) / Al.

[0157] (1) First, the substrate coated with ITO was ultrasonically cleaned with acetone and ethanol for 15 min, then cleaned with deionized water and dried, then dried on a heating plate at 150°C for 10 min, and then irradiated with ultraviolet light (UV) for 20 min.

[0158] (2) Spin-coat PEDOT:PSS material (mass fraction 2.8%) onto the anode at 3000 rpm for 30 s, then heat it with a heating plate and treat it at 150°C for 20 min to obtain a hole injection layer with a thickness of 20 nm.

[0159] (3) The substrate obtained in step (2) is transferred to a nitrogen atmosphere. Take 8 mg / ml of chlorobenzene TFB solution and drop it onto the surface of the hole injection layer. Spin coat it at 3000 rpm for 30 s. Then heat it with a heating plate and treat it at 150°C for 20 min to obtain a hole transport layer with a thickness of 25 nm.

[0160] (4) A hexane solution of quantum dots (CdZnSe / ZnSe / CdZnS / ZnS) was spin-coated onto the hole transport layer at a speed of 2000 rpm for 30 s, and then heated on a heating plate at 80 ℃ for 5 min to obtain a light-emitting layer with a thickness of 30 nm.

[0161] (5) Following the method of Thin Film Example 1, a thin film was prepared on the light-emitting layer to obtain an electron transport layer with a thickness of 35 nm.

[0162] (6) Place the semi-finished device prepared in step (5) into a vacuum coating machine and evacuate the vacuum to 3×10⁻⁶. -4 mbar, with Al was deposited at a rate of 1000s to obtain a cathode with a thickness of 100nm, which was then packaged to obtain a QLED device.

[0163] Device Examples 2 to 17

[0164] Device embodiment n is basically the same as device embodiment 1, except that in step (5) of device embodiment n, a thin film is prepared on the light-emitting layer to form a corresponding electron transport layer, referring to the method of thin film embodiment n. n is any integer from 2 to 17.

[0165] Device Example 18

[0166] The scheme in this embodiment is basically the same as that in device embodiment 1, except that the device structure in this embodiment is: ITO / PEDOT:PSS(20nm) / NiO(25nm) / QD(30nm) / TiO2(35nm) / Ag.

[0167] Accordingly, the preparation steps are adjusted as follows:

[0168] In step (3), a thin film with a thickness of 25 nm is prepared on the hole injection layer according to the method of thin film Example 18 to form a corresponding hole transport layer.

[0169] Step (5) is changed to spin-coating a TiO2 ethanol solution with a concentration of 20 mg / mL onto the light-emitting layer to obtain an electron transport layer with a thickness of 35 nm.

[0170] In step (6), the vapor deposition material is changed to Ag.

[0171] Device Comparison Example 1

[0172] The comparative example scheme of this device is basically the same as that of device example 1, except that the electron transport layer reference thin film is prepared in comparative example 1 in this comparative example.

[0173] Device Comparison Example 2

[0174] The comparative example scheme of this device is basically the same as that of device example 1, except that the electron transport layer reference thin film is prepared in comparative example 2 in this comparative example.

[0175] Device Comparison Example 3

[0176] The comparative scheme of this device is basically the same as that of device embodiment 18, except that the hole transport layer reference thin film of comparative embodiment 3 is prepared in this comparative embodiment.

[0177] Experimental Example

[0178] (I) The films prepared in the above-mentioned film examples and comparative examples were tested for their properties. The results are shown in Tables 1-1 and 1-2. The testing method is as follows:

[0179] (1) The thin film was tested by the BET method to detect the porosity and average pore size of the thin film. The porosity BET test method is as follows: the thin film sample is pretreated at 100-140℃ (not higher than the processing temperature when the thin film is prepared for the device) and 10Pa for 10min to remove the originally adsorbed gas molecules; then the adsorption-desorption test is performed in the range of 0.01-500kPa, and the test system directly reads the required data.

[0180] (2) The surface roughness Rq of the thin film was detected by AFM.

[0181] (3) Thermogravimetric analysis was used to detect the hydroxyl content in the film.

[0182] (4) The doping concentration ratio was semi-quantitatively estimated using energy dispersive spectroscopy (EDS) of thin films, and the doping concentration result was characterized as the y value.

[0183] (5) The conductivity of the material was measured by the four-probe method.

[0184] Table 1-1

[0185]

[0186]

[0187] Table 1-2

[0188]

[0189] Please refer to the table above to see:

[0190] Examples 1 to 18 all exhibit high porosity, average pore size, and hydroxyl groups, indicating that the thin film proposed in this application has a porous structure and is rich in hydroxyl groups; Examples 2 to 17 all exhibit high doping levels, indicating that the method proposed in this application can increase the doping level and flexibly control the doping.

[0191] Examples 1 to 17 have lower electron mobility than Comparative Example 1, and Example 18 has lower hole mobility than Comparative Example 3, indicating that by introducing a porous structure, the charge transport performance of the thin film can be reduced to a certain extent. In addition, comparing Examples 1 to 17, it can be found that by performing element doping, adjusting the type and amount of additives and reaction conditions, the surface roughness can be reduced, the film formation effect can be improved, and the conductivity of the thin film can be flexibly controlled.

[0192] Furthermore, Comparative Example 2 also exhibited a lower electron mobility than Comparative Example 1, indicating that magnesium doping can reduce electron mobility. However, the electron mobility of the film in Comparative Example 2 was extremely low, reaching 10-1. -6 The order of magnitude is insufficient to meet the conductivity requirements of thin films for devices, indicating that the elemental doping method in Comparative Example 2 is not conducive to the preparation of thin films suitable for optoelectronic devices.

[0193] (II) The devices prepared in the above-mentioned device embodiments and device comparison examples were subjected to performance testing. The results are recorded in Table 2. The test methods are as follows:

[0194] (1) The brightness (L) of each optoelectronic device was measured using a Fostar FPD optical characteristic measurement system (including a Marine Optics USB2000, a LabVIEW-controlled QE-PRO spectrometer, a Keithley 2400, a high-precision digital source meter Keithley 6485, an optical fiber with an inner diameter of 50μm, device test probes and fixtures, various connecting cables and data cards, an efficiency test cassette, and a data acquisition system). max ).

[0195] (2) The test method for service life is as follows: Under constant current (2mA) driving, the electroluminescence life analysis of each optoelectronic device is performed using a 128-channel QLED life test system. The time required for each optoelectronic device to decay from the maximum brightness to 95% (T95,h) is recorded. The time required for each optoelectronic device to decay from 100% to 95% at a brightness of 1000nit (T95@1000nit,h) is calculated by the decay fitting formula.

[0196] Table 2

[0197]

[0198]

[0199] Please refer to Table 2, which shows that:

[0200] Examples 1 to 17 have higher L values ​​than Comparative Examples 1 and 2. max T95 and T95@1000nit, Example 18 has a higher L than Comparative Example 3.max The values ​​of T95 and T95@1000nit demonstrate that introducing a porous structure helps improve the luminescence performance and lifespan of the device.

[0201] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A thin film, characterized in that, The thin film is made of N-type inorganic semiconductor or P-type inorganic semiconductor, and the thin film has multiple pores.

2. The thin film according to claim 1, characterized in that, The porosity of the film is 8.5% to 50%; and / or, The average particle size of the N-type inorganic semiconductor is 3–8 nm; and / or, The average particle size of the P-type inorganic semiconductor is 3–8 nm; and / or, The surface roughness Rq of the thin film is 3–10 nm; and / or, The average pore size is 3–15 nm; and / or, The N-type inorganic semiconductor or the P-type inorganic semiconductor is connected to a hydroxyl group.

3. The thin film according to claim 2, characterized in that, In the film, the mass percentage of hydroxyl groups is 5% to 25%.

4. The thin film according to claim 1, characterized in that, The N-type inorganic semiconductor includes one or more of metal oxides and doped metal oxides, wherein the metal oxides include one or more of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the molecular formula of the doped metal oxide is Q. 1-y E y O, where Q is selected from one of Zn, Ti, Sn, Ga, and Al, and E is selected from one or more of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, B, Ca, Cu, Zn, and F. Q and E are not the same, 0.5 ≥ y > 0; and / or, The P-type inorganic semiconductor includes at least one of nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

5. The thin film according to claim 1, characterized in that, The film includes a first film having a porosity of 20% to 50%; or, The thin film includes a second thin film, the material of which further includes a doped material, and the porosity of the second thin film is 8.5% to 20%.

6. The thin film according to claim 5, characterized in that, In the first thin film, the average pore size is 10–15 nm; and / or, The surface roughness Rq1 of the first thin film is 7-10 nm.

7. The thin film according to claim 5, characterized in that, In the second thin film, the average pore size is 3–7 nm; and / or, The surface roughness Rq2 of the second thin film is 3–6 nm; and / or, In the second thin film, at least one of the pores is filled with the doped material, and the doped material is connected to the N-type inorganic semiconductor or the P-type inorganic semiconductor; wherein, the doped material includes one or more of metal oxides, metal halide salts, metal carbonates, and metal sulfates; optionally, the metal element in the metal oxide, the metal element in the metal halide, the metal element in the metal carbonate, and the metal element in the metal sulfate are each independently selected from one or more of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, Ca, Cu, and Zn.

8. A method for preparing a thin film, characterized in that, Includes the following steps: Provide a mixed solution containing the main material, additives and solvent; After depositing the mixed solution, a first heat treatment is performed under a first humidity environment to obtain a thin film; The main material includes any one of N-type inorganic semiconductors and P-type inorganic semiconductors, and the additives include one or more of urea and ammonium salts.

9. The preparation method according to claim 8, characterized in that, In the mixed solution, the concentration of the additive is 0.5–5 mg / mL; and / or, The mass ratio of the additive to the main material is 1:4 to 20; and / or, The ammonium salt includes one or more of ammonium halides, ammonium carbonate, ammonium nitrate, ammonium bicarbonate, ammonium citrate, ammonium acetate, ammonium sulfate, and ammonium phosphate; and / or, The solvent includes at least one of C1-C7 straight-chain alcohols, C2-C4 polyols, C2-C6 alcohol ether compounds, and polyethylene glycol; the C1-C7 straight-chain alcohols include one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, and heptanol; the C2-C6 alcohol ether compounds include one or more of ethylene glycol monobutyl ether and methoxybutanol; the C2-C4 polyols include one or more of glycerol, ethylene glycol, diethylene glycol, dipropylene glycol, and glycerol; and / or, The temperature of the first heat treatment is 100–140°C; and / or, The first heat treatment lasts for 2 to 30 minutes; and / or, The humidity of the first humidity environment is 10% to 50%.

10. The preparation method according to claim 8 or 9, characterized in that, The film may include a first film or a second film; The steps of depositing the mixed solution and then performing a first heat treatment under a first humidity environment to obtain a thin film include: After depositing the mixed solution, a first heat treatment is performed under a first humidity environment to obtain a first thin film with multiple pores; or, After depositing the mixed solution, a first heat treatment is performed under a first humidity environment to obtain a first thin film with multiple pores; a doping material source is provided, the doping material source is disposed on the first thin film, and then a second heat treatment is performed to obtain a second thin film doped with doped material; wherein, in the second thin film, at least one of the pores is filled with doping material, the doping material is connected to the N-type inorganic semiconductor or the P-type inorganic semiconductor, and the doping material includes one or more of metal oxides, metal halide salts, metal carbonates, and metal sulfates.

11. The preparation method according to claim 10, characterized in that, The temperature of the second heat treatment is 60–120°C; and / or, The second heat treatment lasts for 5 to 60 minutes; and / or, The second heat treatment is carried out in a second humidity environment, wherein the humidity of the second humidity environment is 10% to 50%; and / or, The doping material source includes elemental E and one or more E-containing compounds, wherein the E-containing compounds include one or more E-containing oxides, E-containing halide salts, E-containing sulfates, and E-containing carbonates, and E is selected from at least one of Al, Ag, In, W, Mo, Sn, V, Fe, Mg, Co, Ca, Cu, and Zn; and / or, The step of disposing the dopant material source on the first thin film includes: depositing the dopant material source on the first thin film by physical vapor deposition; and / or, The porosity of the first film is 20-50%; and / or, In the first thin film, the average pore size is 10–15 nm; and / or, The surface roughness Rq1 of the first thin film is 7–10 nm; and / or, The porosity of the second film is 8.5–20%; and / or, The porosity of the first film is greater than or equal to the porosity of the second film; and / or, In the second thin film, the average pore size is 3–7 nm; and / or, The surface roughness Rq2 of the second thin film is 3 to 6 nm.

12. An optoelectronic device, characterized in that, The device comprises an anode, one or more functional layers, and a cathode stacked together. The one or more functional layers include one or more hole functional layers and electronic functional layers. One of the hole functional layers or electronic functional layers comprises the thin film according to any one of claims 1 to 7, or the thin film prepared by the preparation method according to any one of claims 8 to 11. When the electronic functional layer comprises the thin film, the material of the electronic functional layer comprises the N-type inorganic semiconductor. When the hole functional layer comprises the thin film, the material of the hole functional layer comprises the P-type inorganic semiconductor.

13. The optoelectronic device according to claim 12, characterized in that, The anode and the cathode are each independently selected from doped metal oxide particle electrodes, metal-metal oxide composite electrodes, graphene electrodes, carbon nanotube electrodes, metal electrodes, or alloy electrodes. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from 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, and ZnS / Al / ZnS. The material of the metal electrode is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba; and / or, The optoelectronic device further includes a light-emitting layer disposed between the hole functional layer and the cathode, or between the electron functional layer and the anode. The material of the light-emitting layer includes one or more of organic light-emitting materials and quantum dot light-emitting materials. The organic light-emitting materials include 4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III), 4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium(III), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, and TBPe fluorescent materials. The quantum dot luminescent material comprises one or more of the following: TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, polymer containing BN covalent bonds, hybrid localized charge transfer excited state material, and exciton complex luminescent material. The quantum dot luminescent material includes at least one of single-structure quantum dots, core-shell quantum dots, and perovskite semiconductor materials. The shell of the core-shell quantum dot comprises one or more layers. The material of the single-structure quantum dot, the core material of the core-shell quantum dot, and the shell material of the core-shell quantum dot respectively include group II-VI compounds, IV-V compounds, etc. At least one of Group I, Group III-V, and Group I-III-VI compounds; wherein the Group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, The compounds are at least one of CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI compounds include at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe.The III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, and AlN P, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInN At least one of P, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI group compounds include at least one of CuInS2, CuInSe2, and AgInS2; the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is RMX3, wherein R is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of them.

14. A display device, characterized in that, Including the optoelectronic devices as described in claim 12 or 13.

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