A method for fabricating high-resolution full-color quantum dot light-emitting diodes with barrier layers

Abstract

The application provides a method for preparing a high-resolution full-color quantum dot light-emitting diode with a barrier layer. A full-color light-emitting layer is prepared by the following method: first, forming a strip-shaped groove by hot nano-imprinting polymer, and depositing a non-light-emitting material into the polymer groove by a solution method to form a stripe; then, depositing a first quantum dot into the gap between the stripes by a solution method, and then longitudinally transferring the shaped quantum dot to a substrate; then, immersing the substrate into a hot solvent to wash away the polymer, so as to leave the first quantum dot stripe wrapped by the non-light-emitting stripe; then, transversely transferring a second quantum dot stripe by the same method; finally, depositing a third quantum dot into the blank position of the cross stripe of the first and second quantum dots by a solution method, so as to form a full-color quantum dot array blocked by the non-light-emitting stripe.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of light emitting diode, and particularly relates to a method for preparing high-resolution full-color quantum dot light emitting diode with barrier layer. BACKGROUND

[0002] There is no method in the prior art that can well realize high-resolution full-color quantum dot light emitting diode. The traditional technology such as photolithography will greatly reduce the performance of quantum dots, the traditional transfer has too low accuracy in pixel point alignment, and inkjet printing will face great difficulties in generating pixels below several microns, so it is difficult to realize the manufacture of high-resolution devices. SUMMARY

[0003] In view of the defects and deficiencies of the prior art, the present application proposes a method for preparing high-resolution full-color quantum dot light emitting diode with barrier layer, and proposes the concept of isolating quantum dot pixels to solve the alignment problem between different color pixels.

[0004] In the design of the scheme, first, a strip-shaped groove is formed by thermal nanoimprint polymer, a non-light-emitting material is deposited into the polymer groove by solution method, and a quantum dot stripe is formed by self-assembly driven by capillary effect;

[0005] Then, red quantum dots are deposited into the gap between the non-light-emitting material stripes by solution method, and then transferred longitudinally to the substrate and immersed in hot solvent to wash away the polymer, so as to leave the red quantum dot stripes sandwiched by the non-light-emitting material stripes;

[0006] Then, green quantum dot stripes are transferred transversely by the same method;

[0007] Finally, blue quantum dots are deposited into the blank position in the red-green cross stripe by solution method to form a full-color quantum dot array.

[0008] The deposition sequence of the above red, green and blue quantum dots can be arbitrarily changed. The polymer herein includes PVB, PS, PMMA and other materials with good thermoplasticity; the light-emitting quantum dots include cadmium quantum dots, indium phosphide quantum dots and other solution-processable light-emitting materials; the non-light-emitting materials include rare earth quantum dots, PS nanospheres, silica nanoparticles, alumina nanoparticles and other solution-processable non-light-emitting metal and polymer nanoparticles, and also include black pigment and other light-absorbing materials.

[0009] The method is simple to operate, has high yield, and is suitable for large-scale industrial production of high-resolution full-color quantum dot light emitting diode; and also indicates the direction for related research.

[0010] The technical scheme specifically adopted by the present application to solve its technical problems is:

[0011] A method for preparing high-resolution full-color quantum dot light-emitting diodes with barrier layers, the full-color light-emitting layer of which is prepared by the following method:

[0012] First, bar-shaped grooves are formed by thermal nano-imprinting of a polymer, and a non-light-emitting material is deposited into the polymer grooves by a solution method to form stripes;

[0013] Then, first quantum dots are deposited into the gaps between the stripes by a solution method, and then the shaped quantum dots are transferred longitudinally onto a substrate, after which the substrate is immersed in a hot solvent to wash away the polymer, leaving first quantum dot stripes sandwiched by non-light-emitting stripes; second quantum dot stripes are prepared by the same method of transverse transfer;

[0014] Finally, third quantum dots are deposited into the blank positions of the intersecting stripes of the first and second quantum dots by a solution method, forming a full-color quantum dot array blocked by non-light-emitting stripes.

[0015] Further, a full-color quantum dot light-emitting diode is prepared according to the structure of substrate-hollow injection layer-hollow transport layer-full-color light-emitting layer-electron transport layer-metal electrode.

[0016] Further, in the transfer process, the non-light-emitting material is self-assembled by capillary effect to form stripes in the polymer grooves, and each groove has a stripe on each of the two inner walls, and then the light-emitting quantum dots are deposited into the gaps between the non-light-emitting stripes by a solution method and transferred onto a substrate.

[0017] Further, the first, second and third quantum dots correspond to three primary colors respectively.

[0018] Further, the polymer material adopts thermoplastic materials including PVB, PMMA, PS, etc.

[0019] Further, the non-light-emitting material includes solution-processable non-light-emitting metals and polymer nanoparticles, such as rare earth quantum dots, PS nanospheres, silica nanoparticles, alumina nanoparticles, and light-absorbing materials such as melanin.

[0020] Further, the red quantum dots, green quantum dots and blue quantum dots adopt solution-processable light-emitting materials including cadmium quantum dots and indium phosphide quantum dots.

[0021] Further, the preparation process includes the following steps:

[0022] 1) Surface cleaning and treatment of the substrate to ensure smoothness;

[0023] 2) Spin coating of a hollow injection layer on the substrate and annealing treatment;

[0024] 3) depositing hole transport layer material on the hole injection layer by spin-coating to form an organic semiconductor film;

[0025] 4) preparing polymer grooves by thermal nano-imprinting;

[0026] 5) forming stripes of non-emissive material on the polymer film by self-assembly;

[0027] 6) transferring first quantum dots to the substrate by transfer printing to form vertical stripes of the first color;

[0028] 7) transferring second quantum dots to the substrate by transfer printing to form horizontal stripes of the second color;

[0029] 8) depositing third quantum dots on the substrate by solution method to form a full-color light-emitting layer with regular arrangement of three colors;

[0030] 9) spin-coating an electron transport layer and performing annealing treatment;

[0031] 10) evaporating silver electrodes;

[0032] 11) encapsulating the device using polymer, glass or other transparent materials to protect and fix the circuit and provide moisture-proof and environmental isolation effect.

[0033] Further, the specific method of step 4) is as follows: first, dissolve the polymer in a solvent, then deposit the polymer film on a smooth PDMS surface by solution method, then cover the nano-silicon template on the polymer film surface, apply a certain pressure, and perform imprinting on a heating table 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 film with groove microstructure.

[0034] Further, the specific method of step 5) is as follows: first, dissolve the non-emissive material in a solvent, then deposit it into the polymer grooves by solution method, and flow to the inner walls of the grooves on both sides under the driving of capillary effect to form non-emissive stripes.

[0035] Further, the specific method of step 6) is as follows: first, dissolve the first quantum dots in a solvent, then deposit them between the non-emissive stripes in the polymer grooves by solution method, then transfer the formed film vertically to the substrate, and finally immerse the substrate in the solvent to wash away the polymer, forming vertical stripes of the first quantum dots arranged vertically;

[0036] The specific method of step 7) is as follows: first, dissolve the second quantum dots in a solvent, then deposit them between the non-emissive stripes in the polymer grooves by solution method, then transfer the formed film horizontally to the substrate, and finally immerse the substrate in the solvent to wash away the polymer, forming horizontal stripes of the second quantum dots arranged horizontally;

[0037] The specific method of step 8) is to dissolve the third quantum dots in an organic solvent and deposit on the substrate by solution method.

[0038] Also, a high-resolution full-color quantum dot light-emitting diode has a structure of substrate-holes injection layer-holes transport layer-full-color light-emitting layer-electron transport layer-metal electrode and is prepared by the method as described above.

[0039] A full-color light-emitting layer structure applied to a high-resolution full-color quantum dot light-emitting diode is prepared by the method as described above.

[0040] Compared with the prior art, the present application and the preferred schemes thereof have at least the following outstanding features and advantages:

[0041] 1. Optimizing the arrangement of quantum dots: using the method of preparing red quantum dots in vertical arrangement and green quantum dots in horizontal arrangement, the alignment problem in the preparation of traditional full-color devices is avoided, and the resolution and stability of the light-emitting layer are improved.

[0042] 2. The non-light-emitting material coated on both sides of the light-emitting quantum dots serves as a barrier material, which blocks the leakage current and avoids the light crosstalk between pixels.

[0043] 3. Superior environmental performance: compared with the traditional chip preparation process, the present application uses chemical synthesis technology and imprinting and transfer printing technology, which reduces the required chemicals and produces relatively less waste during the preparation process, thus having better environmental performance.

[0044] 4. Batch production: the thermal transfer method used in the present application can greatly improve the transfer speed and accuracy of quantum dots, and also increase the robustness and repeatability of the preparation process. BRIEF DESCRIPTION OF DRAWINGS

[0045] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0046] Fig. 1 is a schematic diagram of the deposition process of the non-light-emitting material and the light-emitting quantum dots in the embodiments of the present application;

[0047] Fig. 2 is a schematic diagram of the structure of the full-color light-emitting layer in the embodiments of the present application;

[0048] Fig. 3 is a schematic diagram of the composition structure of the high-resolution full-color quantum dot light-emitting diode in the embodiments of the present application. DETAILED DESCRIPTION

[0049] In order to make the features and advantages of the present patent more obvious and easy to understand, the following embodiments are described in detail as follows: In order to make the features and advantages of the present patent more obvious and easy to understand, the following embodiments are described in detail as follows:

[0050] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0051] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0052] like Figs. 1-3 As shown, this embodiment provides a method for fabricating a high-resolution full-color quantum dot light-emitting diode with a blocking layer. The full-color quantum dot light-emitting diode is fabricated in the following order: substrate - hole injection layer - hole transport layer - full-color light-emitting layer - electron transport layer - metal electrode. The fabrication method of the full-color light-emitting layer is as follows: First, striped trenches are formed by thermal nanoimprinting of polymer. Non-luminescent material is deposited into the polymer trenches using a solution method and self-assembled through capillary effect to form stripes. Then, red quantum dots are spin-coated into the gaps between the non-luminescent stripes. Next, they are longitudinally transferred onto the substrate, and the substrate is immersed in a hot solvent to wash away the polymer, leaving red quantum dot stripes sandwiched between the non-luminescent stripes. Green quantum dot stripes are then transversely transferred using the same method. Finally, blue quantum dots are spin-coated into the blank positions in the red-green cross stripes to form a full-color quantum dot array. The above process is for illustrative purposes only; in practice, the deposition order of red, green, and blue quantum dots can be arbitrarily interchanged.

[0053] During the transfer process, the non-luminescent material forms stripes in the polymer trenches through capillary-driven self-assembly. Each trench has one stripe on each side of its inner wall. Red quantum dots are spin-coated into the gaps between the non-luminescent stripes and then longitudinally transferred onto the substrate. The substrate is then immersed in a hot solvent to wash away the polymer, leaving the red quantum dot stripes sandwiched between the non-luminescent stripes. Green quantum dot stripes are then transferred laterally using the same method. Finally, blue quantum dots are spin-coated into the blank positions within the red-green cross stripes to form a full-color quantum dot array.

[0054] The fabrication method of a high-resolution full-color quantum dot light-emitting diode with a blocking layer specifically includes the following steps:

[0055] 1) Prepare the substrate: Select a suitable substrate (ITO glass is used in this embodiment) and perform surface cleaning and treatment to ensure a smooth surface.

[0056] 2) Spin-coating hole injection layer (HIL): spin-coating hole injection layer material on the processed substrate, and annealing on the heating table. In this embodiment, the hole injection layer material is PEDOT:PSS, and the thickness is about 30 nm.

[0057] 3) Spin-coating hole transport layer: using spin-coating technology to deposit hole transport layer material, such as TFB, on the hole injection layer to generate organic semiconductor thin film, and the thickness is about 50 nm.

[0058] 4) Preparing polymer groove by thermal nano-imprinting; the specific method is as follows: first, dissolving the polymer in a solvent, then spin-coating the thin film on the smooth PDMS surface, then covering the nano-silicon template on the polymer thin film surface, and applying a certain pressure, and imprinting on the heating table above the glass transition temperature of the polymer, and finally removing the pressure after the temperature is lowered to below the glass transition temperature, and taking off the silicon template, to obtain the polymer thin film with groove microstructure.

[0059] 5) Forming non-emitting material stripes on the polymer thin film by solution method; the specific method is as follows: first, dissolving the non-emitting material in a solvent, then spin-coating into the polymer groove, and self-assembling to form non-emitting stripes under the driving of capillary effect;

[0060] 6) Transferring red quantum dots to the substrate by transfer method to form red horizontal lines; the specific method is as follows: first, dissolving the red quantum dots in a solvent, then spin-coating between the non-emitting stripes in the polymer groove, then transferring the formed film longitudinally to the substrate, and finally immersing the substrate in the solvent to wash away the polymer, to form the vertically arranged red quantum dot vertical lines;

[0061] 7) Transferring green quantum dots to the substrate by transfer method to form green horizontal lines; the specific method is as follows: first, dissolving the green quantum dots in a solvent, then spin-coating between the non-emitting stripes in the polymer groove, then transferring the formed film horizontally to the substrate, and finally immersing the substrate in the solvent to wash away the polymer, to form the horizontally arranged green quantum dot horizontal lines;

[0062] 8) Spin-coating blue quantum dots on the substrate to form a full-color light-emitting layer with regular arrangement of red, green and blue colors; the specific method is as follows: dissolving the blue quantum dots in an organic solvent, and depositing on the substrate by spin-coating method, and optimizing the structure and performance of the quantum dots;

[0063] 9) Spin-coating electron transport layer (ETL): spin-coating electron transport layer material, such as ZnO, ZMO solution, etc., on the above-mentioned annealed substrate, and annealing. The thickness of this layer is about 80 nm.

[0064] 10) Evaporating silver electrode: evaporating Ag electrode on the evaporation machine; the thickness of the Ag electrode is 100 nm.

[0065] 11) Encapsulation: encapsulating the device using a polymer, glass, or other transparent material to protect and secure the circuitry and provide moisture and environmental isolation.

[0066] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application in other forms, any skilled in the art can use the disclosed technical content to make changes or modifications as equivalent embodiments. But any simple modification, equivalent change and modification of the above embodiments without departing from the technical solution of the present application, according to the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

[0067] The patent is not limited to the above best mode, anyone can derive other various forms of a method for preparing high-resolution full-color quantum dot light-emitting diode with barrier layer under the inspiration of the patent, any equivalent change and modification made according to the scope of the patent application shall be covered by the patent.

Claims

1. A method for preparing a high-resolution full-color quantum dot light-emitting diode with a barrier layer, characterized in that: a full-color light-emitting layer thereof is prepared by the following method: first, a strip-shaped groove is formed by thermal nano-imprinting of a polymer, and a non-light-emitting material is deposited into the polymer groove by a solution method to form a stripe; then, a first quantum dot is deposited into the gap between the stripes by a solution method, and then the formed quantum dot is transferred longitudinally to a substrate, after which the substrate is immersed in a hot solvent to wash away the polymer, so as to leave the first quantum dot stripe wrapped by the non-light-emitting stripe; a second quantum dot stripe is prepared by the same method in a transverse direction; finally, a third quantum dot is deposited into the blank position of the cross stripe of the first and second quantum dots by a solution method, so as to form a full-color quantum dot array blocked by the non-light-emitting stripe; the preparation process comprises the following steps: 1) surface cleaning and treatment of the substrate to ensure smoothness; 2) spin coating of a hole injection layer on the substrate and annealing treatment; 3) deposition of a hole transport layer material on the hole injection layer by a spin coating technique to form an organic semiconductor thin film; 4) preparation of a polymer groove by thermal nano-imprinting; 5) formation of a stripe of a non-light-emitting material on the polymer thin film by a self-assembly method; 6) transfer of a first quantum dot to the substrate by a transfer method to form a first color vertical line; 7) transfer of a second quantum dot to the substrate by a transfer method to form a second color horizontal line; 8) deposition of a third quantum dot on the substrate by a solution method to form a full-color light-emitting layer with regular arrangement of three colors; 9) spin coating of an electron transport layer and annealing treatment; 10) evaporation of a silver electrode; 11) packaging of the device. 2.The method of claim 1, wherein the method further comprises: forming a barrier layer on the first electrode layer and the second electrode layer. A full-color quantum dot light-emitting diode is prepared according to the structure of substrate-hole injection layer-hole transport layer-full-color light-emitting layer-electron transport layer-metal electrode. 3.The method of claim 1, wherein the method further comprises: forming a barrier layer on the first electrode layer and the second electrode layer. In the transfer process, the non-light-emitting material is self-assembled by capillary effect to form a stripe in the polymer groove, and each groove has a stripe on each of the two inner walls. After the light-emitting quantum dot is deposited into the gap between the non-light-emitting stripes by a solution method, it is transferred to the substrate. 4.The method of claim 1, wherein the method further comprises: forming a barrier layer on the first electrode layer and the second electrode layer. The first, second and third quantum dots correspond to three primary colors, respectively.

5. The method of claim 1, wherein the method further comprises: depositing a barrier layer on the first electrode and the second electrode. The specific method of step 4) is as follows: first, the polymer is dissolved in a solvent, and then deposited into a smooth PDMS surface by a solution method to form a thin film, then a nano-silicon template is covered on the surface of the polymer thin film, and a certain pressure is applied, and the imprinting is performed on a heating table with a temperature higher than the glass transition temperature of the polymer, finally the temperature is lowered to below the glass transition temperature, the pressure is removed, and the silicon template is taken off, to obtain a polymer thin film with a groove microstructure. 6.The method of claim 1, wherein the method further comprises: forming a barrier layer on the first electrode layer and the second electrode layer. The specific method of step 5) is as follows: first, the non-light-emitting material is dissolved in a solvent, and then deposited into the polymer groove by a solution method, and flows and accumulates on the two inner walls of the groove under the driving of capillary effect, to form a non-light-emitting stripe.

7. The method according to claim 1, characterized in that: The specific method of step 6) is: first, dissolving the first quantum dots in a solvent, then depositing between the non-emitting stripes in the polymer groove by solution method, then longitudinally transferring the formed film to a substrate, and finally immersing the substrate in the solvent to wash away the polymer, forming longitudinally arranged first quantum dot vertical lines; The specific method of step 7) is: first, dissolving the second quantum dots in a solvent, then depositing between the non-emitting stripes in the polymer groove by solution method, then transversely transferring the formed film to a substrate, and finally immersing the substrate in the solvent to wash away the polymer, forming transversely arranged second quantum dot horizontal lines; The specific method of step 8) is: dissolving the third quantum dots in an organic solvent, and depositing on the substrate by solution method.

8. A high resolution full color quantum dot light emitting diode, characterized in that: The structure of substrate-hollow injection layer-hollow transmission layer-full color light emitting layer-electron transmission layer-metal electrode is adopted, and is prepared by the method as claimed in any one of claims 1-7.

9. A full-color light-emitting layer structure applied to a high-resolution full-color quantum dot light-emitting diode, characterized in that: It is prepared by the method as claimed in claim 1.

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