A method for preparing high-resolution full-color qled devices by transfer printing

Abstract

The application provides a method for preparing a high-resolution full-color QLED device by transfer printing, and the preparation process of the full-color light-emitting layer is as follows: firstly, a small-period strip-shaped PDMS template is used to transfer a barrier layer material in the horizontal and vertical directions respectively by transfer printing to form a grid-shaped barrier layer; secondly, a large-period strip-shaped PDMS template with a period twice that of the small-period strip-shaped PDMS template is used to transfer a first quantum dot and a second quantum dot in the horizontal and vertical directions respectively; and finally, a third quantum dot is spin-coated to obtain a high-resolution full-color light-emitting layer. The method can realize pixel separation and accurate positioning of the red, green and blue quantum dots in the high-resolution full-color QLED device, and improve the color saturation and display effect of the device. The method is simple and efficient, and can be widely applied in the fields of display devices, optoelectronic devices and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quantum dot display, and particularly relates to a method for preparing a high-resolution full-color QLED device through transfer printing. BACKGROUND

[0002] At present, the requirement for rich colors in the fields of color displays and optoelectronic devices is increasing. Traditional color image preparation methods are often complex, expensive and limit the resolution and color range of preparation. Therefore, developing a simple and efficient high-resolution full-color device preparation method will have broad potential and application prospects. Quantum dots are a new type of luminescent material that can achieve high-brightness and high-saturation color display effects. However, when preparing a high-resolution full-color QLED device, how to accurately position the red, green and blue quantum dot pixel units in the device is a problem to be solved. SUMMARY

[0003] In view of the pixel separation and positioning of different color pixel units of the high-resolution full-color QLED display device, the application provides a method for preparing a high-resolution full-color QLED device through transfer printing, which accurately positions the red, green and blue quantum dot pixel units on the substrate through the use of different size strip-shaped PDMS templates and transfer printing technology, and solves the problem of quantum dot positioning difficulty in the preparation process of traditional high-resolution full-color QLED devices.

[0004] In the core design, the preparation process of the luminescent layer is provided as follows:

[0005] First, a small-period strip-shaped PDMS template is used to transfer a barrier layer material in the horizontal and vertical directions once to form a grid-shaped barrier layer, then a large-period strip-shaped PDMS template with a size twice that of the small-period template is used to transfer the first quantum dots and the second quantum dots in the horizontal and vertical directions, respectively, and finally the third quantum dots are spin-coated to obtain a high-resolution full-color luminescent layer.

[0006] The application can realize pixel separation and accurate positioning of red, green and blue quantum dots in a high-resolution full-color QLED device, improve the color saturation and display effect of the device. The method of the application is simple and efficient, and can be widely applied in the fields of displays, optoelectronic devices and the like.

[0007] The application solves the technical problems by adopting the following technical solutions:

[0008] A method for preparing a high-resolution full-color QLED device through transfer printing,

[0009] The preparation process of the full-color luminescent layer is as follows:

[0010] Firstly, a small-period strip-shaped PDMS template is used to transfer a barrier layer material in horizontal and vertical directions to form a grid-shaped barrier layer by using a transfer technology, and then a large-period strip-shaped PDMS template twice the small period is used to transfer first and second quantum dots in horizontal and vertical directions, respectively, and finally, a third quantum dot is spin-coated to obtain a high-resolution full-color light-emitting layer.

[0011] The above-mentioned transfer technology can be LB-TP (pulling film-transferring) technology, intaglio transfer technology, relief transfer technology, etc.

[0012] Further, firstly, a small-period strip-shaped PDMS template is used to transfer a barrier layer material in horizontal and vertical directions on a substrate to form a grid-shaped barrier layer by using a transfer technology;

[0013] Then, a large-period strip-shaped PDMS template twice the small period is used to transfer a first quantum dot in horizontal direction on the substrate by using a transfer technology;

[0014] Then, a large-period strip-shaped PDMS template is used to transfer a green quantum dot in vertical direction on the substrate processed in the previous step by using a transfer technology, and finally, a blue quantum dot light-emitting layer is prepared on the obtained substrate by using a solution processing method;

[0015] After annealing and curing treatment, a stable high-resolution full-color quantum dot light-emitting layer structure is obtained.

[0016] Further, the preparation of QLED includes the following steps:

[0017] S1: Pretreatment of cleaning and surface treatment of the substrate with anode;

[0018] S2: Prepare a hole injection layer on the pretreated substrate by using a solution processing method, and perform annealing treatment on a heating table;

[0019] S3: Prepare a hole transport layer: prepare a hole transport layer on the annealed substrate by using a solution processing method, and perform annealing treatment on a heating table;

[0020] S4: Perform preparation of a light-emitting layer;

[0021] S5: Prepare an electron transport layer by using a solution processing method, and perform annealing treatment on a heating table;

[0022] S6: After forming the electron transport layer, evaporate a metal cathode, and perform electrode evaporation on a vacuum film plating machine.

[0023] In terms of materials, the hole injection layer material can be one or more of PEDOT:PSS, MoO3 or NiO;

[0024] The hole transport layer material can be one or more of TFB, PVK, Poly:TPD;

[0025] The quantum dot material can be one or more of CdSe, InP, ZnSe, etc.

[0026] The electron transport layer material can be one or more of ZnO nanoparticles, ZnO nanoparticles doped with metal cations, or a mixture of a polymer and ZnO nanoparticles.

[0027] The metal cathode material can be one or more of Ag or Al.

[0028] Further, the first quantum dots, the second quantum dots, and the third quantum dots correspond to three primary colors, respectively. Specifically, the order of the transferred quantum dot lines and the solution-processed quantum dots can be adjusted to be any one of red, green, and blue quantum dots.

[0029] The small-period and large-period template sizes can be adjusted according to actual needs.

[0030] Further, after the metal cathode is evaporated in step S6, the light-emitting diode structure is encapsulated to protect the quantum dots and improve the overall performance.

[0031] Further, the material of the barrier layer is one of blue quantum dots, rare earth quantum dots, or black pigment, which can be used to adjust the light emission of the device. It can also be a general semiconductor material, an insulating material, etc.

[0032] Further, the barrier layer is formed by transferring quantum dots in the horizontal and vertical directions once to form a grid-shaped barrier layer, or by using a grid-shaped template to transfer and directly form a grid-shaped barrier layer.

[0033] Further, the concentration of different color quantum dots is adjusted to optimize the light emission efficiency and color performance of the device.

[0034] In addition, a high-resolution full-color QLED includes, from bottom to top, ITO, a hole injection layer, a hole transport layer, a full-color light-emitting layer, an electron transport layer, and a metal cathode, and is prepared by the method described above.

[0035] A full-color light-emitting layer structure applied to a high-resolution full-color QLED is prepared by the method described above.

[0036] Compared with the prior art, the present application and the preferred embodiments thereof have at least the following outstanding features and advantages:

[0037] 1. By using different sizes of strip-shaped PDMS templates and LB-TP technology, the precise positioning of red, green and blue quantum dots is achieved, which to some extent solves the positioning problem of high-resolution full-color QLED devices.

[0038] 2. The preparation process is simple, without complex photolithography or inkjet printing process, which reduces the cost of device preparation.

[0039] 3. The introduction of the grid-shaped barrier layer effectively avoids the crosstalk between different color pixel units, which is conducive to realizing high-resolution full-color display.

[0040] 4. By adjusting the concentration of different color quantum dots, the luminous efficiency and color performance of the device can be optimized.

[0041] The method uses LB-TP technology combined with solution processing method to realize the preparation of grid-shaped barrier layer and light-emitting layer. The high-resolution full-color QLED device prepared by transfer printing technology has the advantages of high resolution and precise patterning, and the transfer printing technology can accurately control the deposition of quantum dots on the micron or even nanometer scale, which is crucial for realizing high-resolution QLED display. By precisely controlling the position of quantum dots, the quality of individual pixels and overall image can be effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0042] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0043] Figure 1 is a schematic diagram of the preparation process of the full-color light-emitting layer of the embodiment of the present application;

[0044] Figure 2 is a schematic diagram of the transfer printing barrier layer of the embodiment of the present application;

[0045] Figure 3 is a schematic diagram of the transfer printing light-emitting layer of the embodiment of the present application;

[0046] Figure 4 is a schematic diagram of the device structure prepared in the example of the present application. DETAILED DESCRIPTION

[0047] In order to make the features and advantages of the patent more obvious and easy to understand, the following examples are described in detail as follows:

[0048] It should be pointed out that the following detailed description is exemplary and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0049] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0050] As shown in Figures 1-4 The embodiment provides a method for preparing high-resolution full-color QLED devices by transfer printing, first, a hole injection layer and a hole transport layer are prepared on an ITO substrate by using a solution processing technology, then a light-emitting layer is prepared: a grid-shaped barrier layer is formed by transferring a barrier layer material in horizontal and vertical directions on the substrate by using LB-TP technology once, then a red quantum dot light-emitting layer is transferred in the horizontal direction by using a large-period strip-shaped PDMS template, and a green quantum light-emitting layer is transferred in the vertical direction; then a blue quantum dot light-emitting layer is prepared by using a solution processing method, to obtain a high-resolution full-color light-emitting layer; then an electron transport layer is prepared by using a solution processing method, finally, a metal cathode is prepared by using a vacuum evaporation method, to obtain a high-resolution full-color QLED device.

[0051] In the embodiment of the application, the hole injection layer material can be PEDOT:PSS, MoO3, NiO or the like.

[0052] In the embodiment of the application, the hole transport layer material can be TFB, PVK, Poly:TPD, PTAA or the like.

[0053] In the embodiment of the application, the material of the quantum dot can be CdSe, InP, carbon quantum dot or the like.

[0054] In the embodiment of the application, the material of the electron transport layer can be ZnO nanoparticles, ZnO nanoparticles doped with metal cations or a mixture of a polymer and ZnO nanoparticles or the like.

[0055] In the embodiment of the application, the material of the metal cathode can be Ag or Al or the like.

[0056] In the embodiment of the application, the material of the grid-shaped barrier layer can be blue quantum dots, rare earth quantum dots, melanin, a semiconductor material, an insulating material or the like.

[0057] The application is further described below by a more specific example:

[0058] In this example, the LB-TP technology is used to prepare the grid-shaped barrier layer and the light-emitting layer, realizing high-resolution full-color display of quantum dot light-emitting diodes: the key scheme is to use a 1-micron strip-shaped PDMS template to transfer a low-concentration blue quantum dot film in the horizontal and vertical directions on the substrate by LB-TP technology to form a grid-shaped barrier layer, and then use a 2-micron strip-shaped PDMS template to transfer a red quantum dot light-emitting layer in the horizontal direction and a green quantum dot light-emitting layer in the vertical direction; finally, spin-coat high-concentration blue quantum dots to obtain a high-resolution full-color light-emitting layer. After annealing and curing treatment, a stable grid-shaped barrier layer and light-emitting layer structure is obtained.

[0059] The following is introduced according to the overall preparation process:

[0060] Preparation of the substrate: select a suitable substrate with an anode for transfer, and clean and surface treat it.

[0061] Preparation of the hole injection layer: use a solution processing method to prepare the hole injection layer on the pretreated substrate, and perform annealing treatment on the heating table.

[0062] Preparation of the hole transport layer: use a solution processing method to prepare the hole transport layer on the annealed substrate, and perform annealing treatment on the heating table.

[0063] Preparation of the grid-shaped barrier layer: use a 1-um strip-shaped PDMS template to transfer a low-concentration blue quantum dot in the horizontal and vertical directions by LB-TP technology to form a grid-shaped barrier layer, and perform annealing treatment on the heating table after processing.

[0064] Red line transfer: use a 2-um strip-shaped PDMS template to transfer red quantum dots on the substrate obtained in the previous step by LB-TP technology to obtain the required line shape. Perform annealing treatment on the heating table after processing

[0065] Green line transfer: use a 2-um strip-shaped PDMS template to transfer green quantum dots on the substrate obtained in the previous step by LB-TP technology to obtain the required line shape. Perform annealing treatment on the heating table after processing

[0066] Preparation of the electron transport layer: use a solution processing method to prepare the electron transport layer material on the annealed substrate in the previous step, and perform annealing treatment on the heating table.

[0067] Evaporation of the metal cathode: perform evaporation of the Ag electrode on the vacuum coating machine, with a thickness of 100 nm.

[0068] Curing and packaging: perform curing treatment on the transferred quantum dots to enhance their stability and adhesion. Then, use polymers, glass, or other transparent materials to package the light-emitting diode structure to protect the quantum dots and improve overall performance.

[0069] The above merely describes preferred embodiments of the present application, but is not intended to limit the present application in other forms. Any person skilled in the art can make changes or modifications to the above disclosed technical contents to obtain equivalent embodiments. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution of the present application and according to the technical essence of the present application still falls within the protection scope of the present application.

[0070] The present application is not limited to the above preferred embodiments, and anyone can derive other various forms of a transfer printing method for preparing a high-resolution full-color QLED device under the inspiration of the present application. Any equivalent change and modification made within the scope of the present application should be covered by the present application.

Claims

1. A method for preparing high-resolution full-color QLED devices by transfer printing, characterized in that: the preparation process of the full-color light-emitting layer is as follows: firstly, a small-period strip-shaped PDMS template is used to transfer a barrier layer material in the horizontal and vertical directions on the substrate by transfer printing to form a grid-shaped barrier layer; then, a large-period strip-shaped PDMS template twice as large as the small-period one is used to transfer the first quantum dots in the horizontal direction on the substrate by transfer printing; then, a large-period strip-shaped PDMS template is used to transfer the second quantum dots in the vertical direction on the substrate after the previous step by transfer printing; finally, a solution processing method is used to prepare the third quantum dot light-emitting layer on the obtained substrate; after annealing and curing treatment, a stable high-resolution full-color quantum dot light-emitting layer structure is obtained. 2.A method for preparing high-resolution full-color QLED devices by transfer printing according to claim 1, characterized in that: the QLED preparation comprises the following steps: S1: pretreatment of cleaning and surface treatment of the substrate with an anode; S2: using a solution processing method to prepare a hole injection layer on the pretreated substrate, and performing annealing treatment on a heating table; S3: preparing a hole transport layer: using a solution processing method to prepare a hole transport layer on the annealed substrate, and performing annealing treatment on a heating table; S4: preparing a light-emitting layer; S5: using a solution processing method to prepare an electron transport layer, and performing annealing treatment on a heating table; S6: after forming the electron transport layer, evaporating a metal cathode on a vacuum coating machine to evaporate the electrode.

3. The method of claim 1, wherein the method is a method of preparing high-resolution full-color QLED devices by transfer printing. The first, second and third quantum dots correspond to three primary colors respectively.

4. The method for preparing a high-resolution full-color QLED device by transfer printing according to claim 2, characterized in that: After step S6, the metal cathode is evaporated, and the light-emitting diode structure is encapsulated.

5. The method of claim 1, wherein the method is a method of preparing high-resolution full-color QLED devices by transfer printing. The material of the barrier layer is one of blue quantum dots, rare earth quantum dots or black pigment.

6. The method of claim 1, wherein the method is a method of preparing high resolution full-color QLED devices by transfer printing. The barrier layer is prepared by transferring quantum dots in the horizontal and vertical directions to form a grid-shaped barrier layer, or by using a grid-shaped template to transfer to directly form a grid-shaped barrier layer.

7. The method of claim 1, wherein the method is a method of preparing high resolution full-color QLED devices by transfer printing. By adjusting the concentration of quantum dots of different colors, the light-emitting efficiency and color performance of the device are optimized.

8. A high resolution full color QLED, characterized in that: From bottom to top, it comprises ITO, hole injection layer, hole transport layer, full-color light-emitting layer, electron transport layer and metal cathode, and is prepared by the method of any one of claims 1-7. 9.A full-color light-emitting layer structure applied to a high-resolution full-color QLED, characterized in that: It is prepared by the method of claim 1.

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