A method for preparing high-resolution quantum dot light-emitting diodes based on capillary effect driven quantum dot self-assembly

Abstract

The application relates to a method for preparing a high-resolution quantum dot light-emitting diode based on a capillary effect driven quantum dot self-assembly, and belongs to the technical field of light-emitting diodes and other light-emitting devices. The high-resolution quantum dot light-emitting diode is prepared in the order of a substrate-hollow injection layer-hollow transmission layer-light-emitting layer-electron transmission layer-metal electrode, wherein the preparation method of the light-emitting layer is as follows: firstly, a strip-shaped groove is formed in a polymer through hot nano-imprinting; quantum dots are deposited into the polymer groove through a solution method; under the driving of a capillary effect, the quantum dots move to the inner wall of the polymer groove and are accumulated into quantum dot strips; after the polymer substrate with the quantum dot array deposited thereon is transferred to the substrate, the substrate is immersed in a hot solvent to remove the polymer, and the light-emitting quantum dot array is left. The method is simple to operate, high in yield, and suitable for large-scale industrial production of high-resolution quantum dot light-emitting diodes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of light-emitting devices such as light-emitting diodes, and particularly relates to a method for preparing a high-resolution quantum dot light-emitting diode based on capillary effect driving quantum dot self-assembly. BACKGROUND

[0002] Currently, high-resolution quantum dot pixel arrays are mainly prepared by methods such as photolithography, inkjet printing, and transfer printing. Traditional technologies such as photolithography greatly reduce the performance of quantum dots, inkjet printing faces great difficulties in producing pixels below several microns, and transfer printing cannot guarantee the image quality when preparing sub-micron pixels. SUMMARY

[0003] The application aims to overcome the problems in the background art and provide a method for preparing a high-resolution quantum dot light-emitting diode based on capillary effect driving quantum dot self-assembly, which is simple to operate, has high yield, and is suitable for large-scale industrial production of high-resolution quantum dot light-emitting diodes.

[0004] To achieve the above-mentioned purpose, the technical scheme of the application is as follows: a method for preparing a high-resolution quantum dot light-emitting diode based on capillary effect driving quantum dot self-assembly, which prepares a high-resolution quantum dot light-emitting diode in the order of substrate-hole injection layer-hole transport layer-light-emitting layer-electron transport layer-metal electrode.

[0005] In an embodiment of the application, the preparation method of the light-emitting layer is as follows: first, form a strip-shaped polymer groove by thermal nanoimprint polymerization, deposit quantum dots into the polymer groove by a solution method, under the driving of capillary effect, the quantum dots move to the inner wall of the polymer groove and accumulate into quantum dot stripes, and then transfer the polymer substrate with the deposited quantum dot stripes to the substrate, immerse the substrate in a hot solvent to remove the polymer, and leave the light-emitting quantum dot array.

[0006] In an embodiment of the application, in the transfer process, the quantum dots form quantum dot stripes in the polymer groove through capillary effect driving self-assembly, and each polymer groove has a quantum dot stripe on each of the two inner walls.

[0007] In an embodiment of the application, in the transfer process, the external temperature needs to be heated to be higher than the glass transition temperature of the polymer.

[0008] In an embodiment of the application, the polymer includes materials such as PVB, PS, and PMMA that have good thermoplasticity.

[0009] In an embodiment of the application, the quantum dots include solution-processable light-emitting materials such as cadmium quantum dots and indium phosphide quantum dots.

[0010] In an embodiment of the present application, the method comprises the following steps:

[0011] 1) Select a substrate and perform surface cleaning and treatment to ensure smooth surface;

[0012] 2) Spin-coat a hole injection layer on the substrate and perform annealing treatment;

[0013] 3) Deposit a hole transport layer material on the hole injection layer by spin-coating to form an organic semiconductor thin film;

[0014] 4) Prepare a polymer trench by thermal nano-imprinting;

[0015] 5) Deposit quantum dots on the polymer thin film by solution method to form a light-emitting quantum dot array; specifically, first dissolve the light-emitting quantum dots in a solvent, then deposit them into the polymer trench by solution method, and the quantum dots flow and stack on the inner walls of the polymer trench on both sides under the driving of capillary effect to form a light-emitting quantum dot array;

[0016] 6) Transfer the light-emitting quantum dot array to the substrate;

[0017] 7) Spin-coat an electron transport layer and perform annealing treatment;

[0018] 8) Evaporate a silver electrode.

[0019] In an embodiment of the present application, in step 4), the specific method for preparing a polymer trench by thermal nano-imprinting is as follows: first dissolve the polymer in a solvent, then deposit it on a smooth PDMS surface to form a polymer thin film by solution method, then cover a nano-silicon template on the surface of the polymer thin film and apply pressure, perform imprinting on a heating device with a temperature higher than the glass transition temperature of the polymer, and finally remove the pressure after the temperature is lowered to below the glass transition temperature, take off the silicon template, and obtain a polymer thin film with trench microstructure, i.e., a polymer trench.

[0020] In an embodiment of the present application, in step 6), the specific method for transferring the light-emitting quantum dot array to the substrate is as follows: cover the polymer thin film on the PDMS on the substrate, perform transfer on a heating device with a temperature higher than the glass transition temperature of the polymer, after the transfer is completed, immerse the substrate in a hot solvent to remove the polymer thin film, and leave the light-emitting quantum dot array.

[0021] In an embodiment of the present application, it further comprises step 9), i.e., encapsulating the device using a polymer, glass or other transparent material to protect and fix the circuit and provide moisture-proof and environmental isolation effect.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) The present application solves the problem of high cost in preparing sub-micron pixels.

[0024] (2) The method is low in cost, suitable for batch production and high in yield, and is suitable for large-scale industrial production of high-resolution quantum dot light emitting diodes.

[0025] (3) The method avoids damage to quantum dots, protects the electrical properties and stability of the quantum dots, and effectively prolongs the service life of the device. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the deposition process of the luminescent quantum dots in the embodiment of the application;

[0027] Figure 2 is a schematic diagram of the structure of the luminescent layer in the embodiment of the application;

[0028] Figure 3 is a schematic diagram of the composition structure of the high-resolution quantum dot light emitting diode in the embodiment of the application. DETAILED DESCRIPTION

[0029] The technical solutions of the application will be described in detail below with reference to the drawings.

[0030] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0031] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0032] The embodiment provides a method for preparing a high-resolution quantum dot light emitting diode based on capillary effect driven self-assembly of quantum dots, which is prepared in the order of substrate-hollow injection layer-hollow transport layer-luminescent layer-electron transport layer-metal electrode, wherein the preparation method of the luminescent layer is as follows: first, a strip-shaped groove is formed by hot nano-imprinting polymer, quantum dots are deposited into the polymer groove by spin coating, under the driving of capillary effect, the quantum dots move to the inner wall of the polymer groove and accumulate into quantum dot stripes, and after the polymer substrate with quantum dot array deposited thereon is transferred to the substrate, the substrate is immersed in a hot solvent to remove the polymer, leaving a luminescent quantum dot array.

[0033] The present application relates to the manufacture of high-resolution light-emitting diodes by the method of thermal nanoimprint and thermal transfer printing, which provides a direction for the current research in this field. In the transfer printing process, the formation of stripes of luminescent quantum dots in the polymer grooves is driven by the self-assembly of capillary effect, and each groove has a stripe on each of the two inner walls.

[0034] The present application relates to the manufacture of high-resolution light-emitting diodes by the method of thermal nanoimprint and thermal transfer printing, which provides a direction for the current research in this field. In the transfer printing process, the formation of stripes of luminescent quantum dots in the polymer grooves is driven by the self-assembly of capillary effect, and each groove has a stripe on each of the two inner walls.

[0035] 1) Preparation of substrate: select a suitable substrate (ITO glass is used in this embodiment) and perform surface cleaning and treatment to ensure smoothness.

[0036] 2) Spin-coating hole injection layer (HIL): spin-coat hole injection layer material on the treated substrate and perform annealing treatment on the heating table. In this embodiment, the hole injection layer material is PEDOT:PSS, and the thickness is about 30 nm.

[0037] 3) Spin-coating hole transport layer: use spin-coating technology to deposit hole transport layer material, such as TFB, on the hole injection layer to form an organic semiconductor thin film with a thickness of about 50 nm.

[0038] 4) Preparation of polymer grooves by thermal nanoimprint: first dissolve the polymer in a solvent, then spin-coat it onto a smooth PDMS surface to form a thin film, then cover the nano-silicon template onto the polymer thin film surface and apply a certain pressure, and perform imprinting on a heating device with a temperature higher than the glass transition temperature of the polymer. Finally, remove the pressure after the temperature is lowered to below the glass transition temperature, and take off the silicon template to obtain a polymer thin film with groove microstructure.

[0039] 5) Forming a stripe array of luminescent quantum dots on the polymer thin film by spin-coating: first dissolve the luminescent quantum dots in a solvent, then spin-coat them into the polymer grooves, and under the driving of capillary effect, flow and stack along the two inner walls of the grooves to form a luminescent quantum dot array.

[0040] 6) Transfer printing of quantum dot film to the substrate: cover the polymer on the PDMS onto the substrate, perform transfer printing on a heating device with a temperature higher than the glass transition temperature of the polymer, and after transfer printing is completed, immerse the substrate in a hot solvent to remove the polymer thin film, leaving the quantum dot array.

[0041] 7) Spin-coating electron transport layer (ETL): spin-coat electron transport layer material, such as ZnO, ZMO solution, etc., on the above-mentioned annealed substrate and perform annealing treatment. The thickness of this layer is about 80 nm.

[0042] 8) Evaporate silver electrode: Evaporate Ag electrode on the evaporation machine; the thickness of the Ag electrode is 100 nm.

[0043] 9) Encapsulation: encapsulate the device using polymers, glass or other transparent materials to protect and fix the circuit and provide moisture-proof and environmental isolation effects.

[0044] Technical advantages and innovations of the present application:

[0045] 1. Low cost: The present application adopts a quantum dot self-assembly method to form a sub-micron quantum dot pattern array on a micron-level line width template, and the materials used are very low in price.

[0046] 2. Superior environmental performance: Compared with traditional chip preparation processes, the present application adopts chemical synthesis technology and imprinting and transfer printing technology, which reduces the required chemicals and relatively less waste is generated during the preparation process, thus having better environmental performance.

[0047] 3. Batch production: The hot transfer method used in the present application can greatly improve the quantum dot transfer speed and transfer precision, and also increase the robustness and repeatability of the preparation process.

[0048] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to obtain equivalent embodiments. However, any simple modification, equivalent change and modification of the above embodiments without departing from the technical solution of the present application, and according to the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A method for preparing high-resolution quantum dot light-emitting diodes based on capillary effect driven self-assembly of quantum dots, characterized in that, A high-resolution quantum dot light-emitting diode is prepared in the order of substrate-hole injection layer-hole transport layer-light-emitting layer-electron transport layer-metal electrode; the preparation method of the light-emitting layer is as follows: first, a strip-shaped polymer groove is formed by hot nano-imprinting polymerization, quantum dots are deposited into the polymer groove by a solution method, under the driving of capillary effect, the quantum dots move to the inner wall of the polymer groove and are stacked into quantum dot stripes, after the polymer substrate with the deposited quantum dot stripes is transferred to the substrate, the substrate is immersed in a hot solvent to remove the polymer, leaving a light-emitting quantum dot array; in the transfer process, the quantum dots form quantum dot stripes in the polymer groove through self-assembly driven by capillary effect, and there is a quantum dot stripe beside each inner wall of the polymer groove; in the transfer process, the temperature needs to be heated to be higher than the glass transition temperature of the polymer.

2. The method for preparing high-resolution quantum dot light-emitting diodes based on self-assembly of quantum dots driven by capillary effect according to claim 1, characterized in that, The polymer includes PVB, PS, PMMA and the like which are materials with good thermoplasticity.

3. The method for fabricating high-resolution quantum dot light-emitting diodes based on capillary effect-driven quantum dot self-assembly according to claim 1, characterized in that, The quantum dots include cadmium quantum dots, indium phosphide quantum dots and the like which are solution-processable light-emitting materials.

4. The method for fabricating high-resolution quantum dot light-emitting diodes based on capillary effect-driven quantum dot self-assembly according to claim 1, characterized in that, The method includes the following steps: 1) selecting a substrate and performing surface cleaning and treatment to ensure smooth surface; 2) spin-coating a hole injection layer on the substrate and performing annealing treatment; 3) depositing a hole transport layer material on the hole injection layer by spin-coating technology to generate an organic semiconductor thin film; 4) preparing a polymer groove by hot nano-imprinting; 5) depositing quantum dots on the polymer thin film by a solution method to form a light-emitting quantum dot array; specifically, first, dissolving light-emitting quantum dots in a solvent, then depositing into the polymer groove by a solution method, under the driving of capillary effect, the quantum dots flow to the inner wall of the polymer groove and are stacked to form a light-emitting quantum dot array; 6) transferring the light-emitting quantum dot array to the substrate; 7) spin-coating an electron transport layer and performing annealing treatment; 8) evaporating a silver electrode.

5. The method of claim 4, wherein the method comprises the following steps: 1) preparing a quantum dot solution; 2) preparing a substrate; 3) preparing a cap layer; 4) preparing a quantum dot self-assembly layer; 5) preparing a quantum dot light-emitting diode; and 6) preparing a quantum dot light-emitting diode with high resolution. In step 4), the specific method for preparing the polymer groove by hot nano-imprinting is as follows: first, dissolving the polymer in a solvent, then depositing onto a smooth PDMS surface to form a polymer thin film by a solution method, then covering a nano-silicon template onto the surface of the polymer thin film and applying pressure, performing imprinting on a heating device with a temperature higher than the glass transition temperature of the polymer, and finally removing the pressure and taking off the silicon template after the temperature is lowered to be lower than the glass transition temperature, to obtain a polymer thin film with groove microstructure, i.e., a polymer groove.

6. The method for fabricating high-resolution quantum dot light-emitting diodes based on capillary effect-driven quantum dot self-assembly according to claim 5, characterized in that, In step 6), the specific method for transferring the light-emitting quantum dot array to the substrate is as follows: covering the polymer thin film on the PDMS onto the substrate, performing transfer on a heating device with a temperature higher than the glass transition temperature of the polymer, and after the transfer is completed, immersing the substrate in a hot solvent to remove the polymer thin film, leaving a light-emitting quantum dot array.

7. The method for fabricating high-resolution quantum dot light-emitting diodes based on capillary effect-driven quantum dot self-assembly according to claim 4, characterized in that, Step 9) is further included, i.e., using a polymer or glass transparent material to encapsulate the device, to protect and fix the circuit and provide moisture-proof and environmental isolation effect.

Images