Full-color QLED device and manufacturing method therefor

Abstract

The present invention relates to a full-color QLED device and a manufacturing method therefor. The device comprises: a substrate; pixel isolation unit banks, which are distributed on the substrate in an array; a full-color QD array, any QD functional unit in the full-color QD array being arranged in a corresponding pixel isolation unit bank; a photoresist protection layer, which is arranged on the full-color QD array; and a transparent electrode, which is arranged above the photoresist protection layer, wherein the QD function units are loaded in the pixel isolation unit banks by means of successive photolithography cleaning. According to the present invention, the photoresist protection layer is prepared on the full-color QD array in the pixel isolation unit banks by means of multiple photolithography-assisted processes, to protect the full-color QD array, thereby achieving a full-color QLED device having high pixel density, reducing electron injection, achieving electron-hole injection balance, and improving the performance of the full-color QLED device.

Description

Full-color QLED device and preparation method thereof

[0001] Related applications

[0002] This application claims priority to Chinese invention patent application No. 202410153584.X filed on February 2, 2024, entitled “Full-color QLED device and its preparation method”. Technical Field

[0003] The present disclosure relates to the field of optoelectronic technology, and in particular to a full-color QLED device and a preparation method thereof. Background Art

[0004] Quantum dot light-emitting diode (QLED) is a new type of electroluminescent device that uses charge injection to activate quantum dots to emit light. It has the characteristics of wide color gamut, high brightness, and low cost of solution processing, which can meet the application requirements of display.

[0005] Existing methods for achieving full-color QLED devices include transfer printing, inkjet printing, and quantum dot lithography. In inkjet printing, a patterned display device can be fabricated by first preparing a pixel isolation unit bank and then printing ink. For example, Chinese invention patent publication number CN 106876566 B discloses a technical solution for first preparing a functional high-thermal-conductivity pixel isolation bank, depositing an optical layer within the pixel area, and then preparing an electrode layer to complete the QLED device. However, this solution can only produce monochrome QLED devices and cannot meet the requirements of full-color QLED displays.

[0006] Moreover, inkjet printing solutions are difficult to achieve pixel units below 20 microns on a large scale. They have problems such as low efficiency and coffee rings, making them difficult to apply to the preparation of high-pixel density display devices.

[0007] Summary of the Invention

[0008] The present invention innovatively proposes a full-color QLED device and a preparation method thereof. Based on the inkjet printing scheme, a photoresist protective layer is prepared by multiple photolithography-assisted methods to protect the quantum dot light-emitting layers of different colors in the full-color QD array, thereby realizing the efficient preparation of full-color QLED devices with high pixel density. Moreover, the quantum dots do not need to undergo ligand exchange, and there is no organic polymer barrier between the QDs, which does not affect the photoelectric performance and stability of the QDs. The method is compatible with the preparation method of traditional QLEDs and is simple.

[0009] According to a first aspect of the present invention, a full-color QLED device is provided, comprising: a substrate; a pixel isolation unit bank, the pixel isolation unit bank being distributed in an array on the substrate; a full-color QD array, any QD functional unit in the full-color QD array being arranged in the pixel isolation unit bank; a photoresist protective layer, the photoresist protective layer being arranged above the full-color QD array; and a transparent electrode, the transparent electrode being arranged above the photoresist protective layer, wherein the QD functional units in the full-color QD array are filled in the pixel isolation unit bank by successive photolithographic cleaning.

[0010] In some optional embodiments, the QD functional unit includes a hole injection layer, a hole transport layer and a quantum dot light-emitting layer from bottom to top, wherein the colors of the quantum dot light-emitting layers in two adjacent QD functional units are different along the length and / or width direction of the substrate.

[0011] In some optional embodiments, it further includes: an electron transport layer, wherein the electron transport layer is arranged between the photoresist protection layer and the transparent electrode, or the electron transport layer is arranged between the photoresist protection layer and the full-color QD array.

[0012] In some optional embodiments, the QD functional unit includes an electron transport layer and a quantum dot light-emitting layer from bottom to top, wherein the colors of the quantum dot light-emitting layers in two adjacent QD functional units are different along the length direction and / or width direction of the substrate; the device also includes: a hole transport layer, wherein the hole transport layer is arranged above the photoresist protective layer; and a hole injection layer, wherein the hole injection layer is arranged between the hole transport layer and the transparent electrode.

[0013] In some optional implementations, the size of the pixel isolation unit bank is 0.1 micrometer to 2000 micrometers.

[0014] In some optional embodiments, the material of the photoresist protection layer is a photoresist containing a hole semiconductor material.

[0015] According to a second aspect of the present invention, a method for preparing a full-color QLED device is provided, comprising: preparing a plurality of pixel isolation units (banks) distributed in an array above a substrate; sequentially preparing functional layers of different colors within the plurality of pixel isolation units (banks) by repeatedly utilizing a photolithography cleaning method; and preparing a transparent electrode above the functional layers of different colors, wherein the process of preparing the functional layer using the photolithography cleaning method each time comprises: depositing a functional layer of a current color within the pixel isolation unit bank and applying photoresist; shielding and exposing the functional layer using a current light shielding plate having patterned slits to generate a photoresist protective layer above the functional layer in an unshielded area; and cleaning the functional layer and re-depositing a functional layer of the next color within the cleaned pixel isolation unit bank.

[0016] In some optional embodiments, the process of preparing the functional layer includes at least: sequentially depositing a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light-emitting layer.

[0017] In some optional embodiments, the method further includes depositing an electron transport layer above the quantum dot light-emitting layer.

[0018] In some optional embodiments, the method further includes depositing an electron transport layer between the photoresist protection layer and the transparent electrode.

[0019] In some optional embodiments, the process of preparing the functional layer includes at least: sequentially depositing an electron transport layer and a quantum dot light-emitting layer in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light-emitting layer.

[0020] In some optional implementations, the method further includes: sequentially depositing a hole transport layer and a hole injection layer on top of the photoresist protection layer.

[0021] In some optional embodiments, the photoresist is applied by spin coating or spray coating, and the photoresist is a photoresist containing a hole semiconductor material.

[0022] In some optional implementations, the method further includes: cleaning the surface of the substrate on which the pixel isolation unit bank is prepared.

[0023] In some optional embodiments, the patterned gaps in the light shielding plate used to shield the functional layer at any two times are different.

[0024] In some optional embodiments, the functional layers in two adjacent pixel isolation units bank have different colors along the length direction and / or width direction of the substrate.

[0025] Compared with the prior art, one or more embodiments of the above scheme have at least the following advantages or beneficial effects: The present invention innovatively combines multiple lithography-assisted methods with inkjet printing schemes in full-color QLED devices and their preparation. A photoresist protective layer is prepared after each completion of the quantum dot light-emitting layer to protect the quantum dot light-emitting layer so as to clean off the unprotected part and prepare for the deposition of a quantum dot light-emitting layer of another color, thereby realizing the efficient preparation of high-pixel-density full-color QLED devices. Moreover, quantum dots do not require ligand exchange, and there is no organic polymer barrier between QDs, which does not affect the photoelectric performance and stability of QDs. It is compatible with traditional QLED preparation methods and the method is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. It should be noted that for the sake of clarity, the components illustrated in the accompanying drawings are not necessarily drawn to scale.

[0027] FIG. 1 is a schematic diagram of a full-color QLED device according to an embodiment of the present invention.

[0028] FIG. 2 is a partial cross-sectional schematic diagram of a full-color QLED device according to an embodiment of the present invention.

[0029] FIG3 is a flow chart of a method for preparing a full-color QLED device according to an embodiment of the present invention.

[0030] FIG. 4 is a schematic diagram of a UV irradiation treatment process according to an embodiment of the present invention.

[0031] FIG. 5 is a schematic diagram of a product after cleaning according to an embodiment of the present invention.

[0032] FIG. 6 is a schematic diagram of redepositing a second functional layer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings and examples, so that the present invention can fully understand how to apply technical means to solve technical problems and achieve technical effects, and thus implement the invention accordingly. It should be noted that, as long as no conflict exists, the various embodiments of the present invention and the various features of the embodiments can be combined with each other, and the resulting technical solutions are all within the scope of protection of the present invention.

[0034] Meanwhile, in the following description, for the purpose of explanation, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be implemented without using the specific details herein or the particular manner described.

[0035] The present invention innovatively proposes a full-color QLED device. FIG1 is a schematic diagram of a full-color QLED device according to an embodiment of the present invention. FIG2 is a partial cross-sectional schematic diagram of a full-color QLED device according to an embodiment of the present invention. As shown in FIG1 and FIG2, the full-color QLED device may include: a substrate 31; a pixel isolation unit bank 26, wherein a plurality of pixel isolation units bank 26 are arrayed on the substrate 31; a full-color QD array, wherein any QD functional unit 25 in the full-color QD array is arranged in the pixel isolation unit bank 26; a photoresist protection layer 24, wherein the photoresist protection layer 24 is arranged above the full-color QD array; a transparent electrode 28, wherein the transparent electrode 28 is arranged above the photoresist protection layer 24, wherein each QD functional unit in the full-color QD array is sequentially filled between the pixel isolation unit banks by successive photolithography cleaning.

[0036] In the embodiment of the present invention, the substrate 31 serves as a driving circuit substrate and is the anode electrode of the full-color QLED device. Correspondingly, the transparent electrode 28 serves as the cathode electrode of the full-color QLED device.

[0037] In the embodiment of the present invention, the pixel isolation unit bank 26 may be prepared by a lift-off method, and the photoresist polymer used may include: polyacrylic acid, polyimide, thiol-ene and other photocurable adhesive polymers.

[0038] It should be noted that the QLED device structure includes two types: an upright QLED structure and an inverted QLED structure. The upright QLED structure is composed of, from bottom to top: a hole injection layer (HIL), a hole transport layer (HTL), a quantum dot (QD) light-emitting layer, an electron transport layer (ETL), and a transparent electrode; the inverted QLED structure is composed of, from bottom to top: an electron transport layer (ETL), a quantum dot (QD) light-emitting layer, a hole transport layer (HTL), a hole injection layer (HIL), and a transparent electrode. The luminous color of the QLED device is mainly determined by the quantum dot light-emitting layer. Therefore, the position of the photoresist protective layer 24 can be determined based on the quantum dot light-emitting layer. Combined with the sequential photolithography cleaning method, quantum dot light-emitting layers with different colors are used as light-emitting areas of different colors to form an array of QD functional units, which are sequentially filled between the pixel isolation unit banks (each photolithography cleaning completes the filling of a color light-emitting layer, and different color light-emitting layers or light-emitting areas are arranged at regular intervals).

[0039] Taking the upright QLED structure as an example, after preparing the pixel isolation unit bank 26 on the substrate 31, UV irradiation and plasma treatment can be performed to clean the surface to prepare multiple pixel isolation units 26 distributed in an array. Therefore, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer can be deposited in sequence on the substrate within the pixel isolation unit bank 26 to form a QD functional unit 25 in each pixel isolation unit bank 26, forming a full-color QD array.

[0040] It should be noted that the preparation methods of the hole injection layer, hole transport layer, and quantum dot light-emitting layer in the full-color QD array can be chemical methods or physical methods, among which the physical methods include but are not limited to spraying, spin coating, roll coating, printing, printing, inkjet, thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, and multi-arc ion plating; chemical methods include but are not limited to chemical vapor deposition, continuous ion layer adsorption and reaction, anodization, electrolytic deposition, and co-precipitation.

[0041] Afterwards, photoresist is applied on the quantum dot light-emitting layer deposited this time by spin coating or spraying semiconductor polymer photoresist, and is blocked and exposed using a light shield with gaps to solidify the photoresist in the unblocked area to form a photoresist protection layer 24. During cleaning, the hole injection layer, hole transport layer, and quantum dot light-emitting layer below it are protected to form a type of QD functional unit 25 (one color); while the photoresist in the blocked part is still liquid, and can be removed together with the hole injection layer, hole transport layer, and quantum dot light-emitting layer below it by cleaning.

[0042] Therefore, by re-depositing the hole injection layer, hole transport layer, and quantum dot light-emitting layer (of different colors) on the cleaned substrate, applying photoresist, blocking, exposing, and cleaning again, another type of QD functional unit 25 (of another color) can be formed. Therefore, by repeating the above process multiple times, QD functional units 25 of multiple colors can be prepared to form a full-color QD array.

[0043] At the same time, by adjusting the shape and position of the slit of the light shield each time, different positions of the substrate 31 can be blocked to prepare full-color QD arrays with different patterns. The specific process will not be repeated here.

[0044] For example, a full-color QLED device is prepared based on the three colors of red, green and blue, with every three columns as a cycle, as shown in Figure 1. First, a hole injection layer, a hole transport layer, and a red quantum dot light-emitting layer are deposited on the entire substrate 31, and a light shielding plate with gaps in the 1st column, the 4th column, the 7th column, ... is used for shielding. After exposure and cleaning, a red QD functional unit 32 can be formed at the corresponding position; then, the hole injection layer, the hole transport layer and the green quantum dot light-emitting layer are re-deposited, and a light shielding plate with gaps in the 2nd column, the 5th column, the 8th column, ... is used for shielding. After exposure and cleaning, a green QD functional unit 33 can be formed at the corresponding position; repeat the above process, and a blue QD functional unit 34 can be formed in the 3rd column, the 6th column, the 9th column, ... to form a full-color QD array.

[0045] Subsequently, the electron transport layer 27 and the transparent electrode 28 are deposited to complete the preparation of the full-color QLED device.

[0046] Based on the inkjet printing solution, the present invention uses multiple photolithography-assisted methods to prepare a photoresist protective layer to protect QD functional units deposited at different times, and prepares QD functional units of different colors in batches to form a full-color QD array, thereby obtaining a full-color QLED device. This realizes the efficient preparation of full-color QLED devices with high pixel density, and the quantum dots do not require ligand exchange, and there is no organic polymer barrier between QDs, which does not affect the photoelectric performance and stability of QDs.

[0047] In an embodiment of the present invention, for an upright QLED structure, the QD functional unit 25 includes, from bottom to top, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer, wherein, along the length direction and / or width direction of the substrate 31, the colors of the quantum dot light-emitting layers in two adjacent QD functional units 25 are different, and the quantum dot light-emitting layers of each color are arranged side by side. The color types of the QD functional unit 25 include at least three, which are the three primary colors: red, green, and blue, and can also be set to other colors according to actual needs.

[0048] In an embodiment of the present invention, the device further includes an electron transport layer 27 , which is disposed between the photoresist protection layer 24 and the transparent electrode 28 , or between the photoresist protection layer 24 and the full-color QD array.

[0049] In an embodiment of the present invention, for an inverted QLED structure, the QD functional unit includes, from bottom to top, an electron transport layer and a quantum dot light-emitting layer, wherein, along the length direction and / or width direction of the substrate, the colors of the quantum dot light-emitting layers in two adjacent QD functional units are different, and the quantum dot light-emitting layers of each color are arranged side by side; the device also includes: a hole transport layer, the hole transport layer is arranged above the photoresist protective layer; and a hole injection layer, the hole injection layer is arranged between the hole transport layer and the transparent electrode.

[0050] It should be noted that the preparation process of the full-color QLED device with an inverted QLED structure is similar to that of the upright QLED structure and will not be repeated here.

[0051] In the embodiment of the present invention, since the pixel isolation unit bank 26 can be prepared by the lift-off method, the size of the pixel isolation unit bank 26 can be adjusted according to actual needs. The size of the pixel isolation unit bank 26 is 0.1 microns to 2000 microns. Combined with the photoresist protection layer 24 prepared by spraying photoresist, the unprotected area is cleaned and QD functional units of different colors are re-deposited. Therefore, the inkjet printing solution can be used to achieve large-scale preparation of QD functional units (pixel units) below 20 microns.

[0052] In the embodiment of the present invention, the material of the photoresist protection layer 24 is a photoresist containing a hole semiconductor material, such as TFB, poly TPD, PEDOT:PSS, polyaniline, polypyrrole, etc.

[0053] The present invention also proposes a method for preparing a full-color QLED device. FIG3 is a flow chart of a method for preparing a full-color QLED device according to an embodiment of the present invention. As shown in FIG3 , the method for preparing a full-color QLED device may include:

[0054] S301: preparing a plurality of pixel isolation units (banks) distributed in an array above a substrate; for example, the pixel isolation units may be prepared by a lift-off method, and the types of photolithographic polymers used may include: polyacrylic acid, polyimide, thiol-ene and other photocurable adhesive polymers.

[0055] S302: Repeating the photolithography cleaning method in a plurality of pixel isolation units (banks) to sequentially prepare functional layers of different colors; wherein, the process of preparing the functional layer in any one time using the photolithography cleaning method includes: depositing a functional layer of the current color in the pixel isolation unit bank and applying photoresist; shielding and exposing the functional layer using the current light shielding plate with patterned slits to form a photoresist protective layer above the functional layer in the unshielded area; cleaning the functional layer, and re-depositing the functional layer of the next color in the cleaned pixel isolation unit bank.

[0056] S303: Prepare transparent electrodes on functional layers of different colors.

[0057] It should be noted that the QLED device structure includes two types: an upright QLED structure and an inverted QLED structure. The upright QLED structure is composed of, from bottom to top: a hole injection layer (HIL), a hole transport layer (HTL), a quantum dot light-emitting layer (QD layer), an electron transport layer (ETL), and a transparent electrode; the inverted QLED structure is composed of, from bottom to top: an electron transport layer (ETL), a quantum dot light-emitting layer (QD layer), a hole transport layer (HTL), a hole injection layer (HIL), and a transparent electrode. The luminous color of the QLED device is mainly determined by the quantum dot light-emitting layer. Therefore, the position of the photoresist protective layer 24 can be determined based on the quantum dot light-emitting layer.

[0058] Taking the upright QLED structure as an example, after preparing multiple pixel isolation banks arranged in an array on a substrate, inkjet printing is used to sequentially deposit a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer (one color) on the substrate within the pixel isolation bank, serving as the current functional layers. Photoresist is then applied to the entire surface above the current functional layers.

[0059] Afterwards, as shown in FIG4 , a light shield with patterned slits is used for shielding and exposure, so that the photoresist in the unblocked area is solidified to form a photoresist protection layer, and the hole injection layer, hole transport layer, and quantum dot light-emitting layer (current functional layer) thereunder are protected during cleaning, that is, a functional layer of one color can be formed in the pixel isolation unit bank in the unblocked area; while the photoresist in the blocked part is still liquid, and can be removed together with the hole injection layer, hole transport layer, and quantum dot light-emitting layer thereunder by cleaning, as shown in FIG5 .

[0060] Then, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer (of another color) are re-deposited in the cleaned pixel isolation unit bank as the next functional layer. The above process is repeated, and photoresist is applied, masking, exposure, and cleaning are performed again to form a functional layer 65 of another color, as shown in Figure 6. Therefore, functional layers of different colors can be prepared by repeating the above process multiple times.

[0061] Finally, an electron transport layer and a transparent electrode are prepared on top of the functional layer to complete the preparation of a full-color QLED device with an upright QLED structure.

[0062] It should be noted that when blocking any two colors of functional layers, the patterned gaps in the light shielding plate used are different, that is, by adjusting the gap shape and position of the light shielding plate each time, different positions of the substrate can be blocked to prepare full-color QD arrays with different patterns. The specific process will not be repeated here.

[0063] In the embodiment of the present invention, along the length direction and / or width direction of the substrate, the functional layers in two adjacent pixel isolation units (bank) have different colors.

[0064] In an embodiment of the present invention, for an upright QLED structure, the process of preparing the functional layer includes at least: sequentially depositing a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light-emitting layer. The color types of the quantum dot light-emitting layer include at least three primary colors: red, green, and blue, and can also be set to other colors according to actual needs.

[0065] In an embodiment of the present invention, the method further includes: depositing an electron transport layer above the quantum dot light-emitting layer.

[0066] In an embodiment of the present invention, the method further includes depositing an electron transport layer between the photoresist protective layer and the transparent electrode. Specifically, after depositing the quantum dot light-emitting layer, photoresist is sprayed on the layer, and various functional layers are formed by combining shielding, exposure, and cleaning. After all functional layers are formed, the electron transport layer and the transparent electrode are sequentially deposited. This eliminates the need for multiple electron transport layer depositions, saving material.

[0067] In an embodiment of the present invention, for an inverted QLED structure, the process of preparing the functional layer includes at least: sequentially depositing an electron transport layer and a quantum dot light-emitting layer in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light-emitting layer. The specific preparation process is similar to that of the upright QLED structure and will not be repeated here.

[0068] In an embodiment of the present invention, the material of the quantum dot light-emitting layer may be at least one of a II-VIA compound, a IV-VIA compound, or a III-VA compound, including quantum dots such as CdTe, CdS, CdSe, CdSeS, ZnSe, InP, PbS, CuInS, ZnSe, ZnCdSe, and CdZnSeS, as well as derivative structures coated with one or more layers of core-shell structures, such as at least one of perovskite quantum dot materials, organic-inorganic perovskite quantum dots, and all-inorganic perovskite quantum dots.

[0069] In an embodiment of the present invention, for an inverted QLED structure, the corresponding preparation method further includes: sequentially depositing a hole transport layer and a hole injection layer on top of the photoresist protection layer.

[0070] Among them, the hole injection layer material includes one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN), copper phthalocyanine (CuPc), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane (F4-TCNQ), polythiophene-thiophene (PTT) doped with poly(perfluoroethylene-perfluoroether sulfonic acid) (PFFSA), MoO3, V2O5, WO3 or ReO3, etc.

[0071] The hole transport layer material includes one or more of (9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4"-tris(carbazol-9-yl)aniline (TCTA), 4,4'-bis(9-carbazol)biphenyl (CBP), N,N'-diphenyl-N,N'(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), etc.

[0072] The transparent electrode can be a reflective electrode (bottom emission type) or a transparent electrode (top emission type) depending on the light emitting type of the quantum dots. The material of the reflective electrode is a highly conductive metal film such as Al or Ag, and the material of the transparent electrode is a conductive metal oxide such as ITO, IZO, or a highly conductive organic conductive material such as graphene and conductive polymers.

[0073] In the embodiment of the present invention, the photoresist is applied by spin coating or spray coating, and the photoresist is a photoresist containing a hole semiconductor material.

[0074] In an embodiment of the present invention, the method further comprises: cleaning the surface of the substrate on which the pixel isolation unit bank is prepared.

[0075] In the embodiment of the present invention, the size of the pixel isolation unit bank is 0.1 micrometer to 2000 micrometers.

[0076] Example 1:

[0077] Taking the preparation of an upright patterned full-color QLED device as an example, the preparation method in the embodiment of the present invention includes:

[0078] Step 1: Clean the substrate and place it in deionized water, ethanol, acetone, and ethanol in sequence for ultrasonic treatment. The ultrasonic treatment time for each time is 10 minutes.

[0079] Step 2: Apply photoresist and perform exposure and development to prepare a pixel isolation unit bank with a length and width of 15*10 microns as a pixel unit.

[0080] Step 3: Prepare the QD functional layer. During the preparation process, the entire surface is spray-coated with PEDOT:PSS as a hole injection layer and dried at 130°C for 20 minutes to a thickness of approximately 40nm. Then, the entire surface is spray-coated with TFB as a hole transport layer and dried at 130°C for 20 minutes to a thickness of approximately 30nm. Finally, the entire surface is deposited with red CdSe quantum dots to a thickness of 30nm.

[0081] Step 4: spraying a photoresist containing a PEDOT:PSS polymer, shielding it with a light shield of a specific pattern, and exposing it to solidify only the specific (unshielded) position, and developing it to prepare a patterned pixel unit.

[0082] Step 5: Clean and repeat steps 3 to 4 to complete the preparation of the three-color (red, green, and blue) full-color QD functional layer.

[0083] Step 6: Spray ZnO solution on the entire surface and bake it at 100°C for 10 minutes, with a thickness of 50nm, as an electron transport layer; evaporate ITO cathode layer to form a transparent electrode with a thickness of 50nm.

[0084] Complete the production of patterned, full-color QLED devices.

[0085] Example 2:

[0086] Taking the preparation of an upright patterned full-color QLED device as an example, the preparation method in the embodiment of the present invention includes:

[0087] Step 1: Clean the substrate and place it in deionized water, ethanol, acetone, and ethanol in sequence for ultrasonic treatment. The ultrasonic treatment time for each time is 10 minutes.

[0088] Step 2: Apply photoresist and perform exposure and development to prepare a pixel isolation unit bank with a length and width of 20*50 microns or 100*500 microns as a pixel unit.

[0089] Step 3: Prepare the QD functional layer. During the preparation process, the entire surface is sprayed with PEDOT:PSS as a hole injection layer and dried at 130°C for 20 minutes to a thickness of approximately 40nm. Then, the entire surface is sprayed with TFB as a hole transport layer and dried at 130°C for 20 minutes to a thickness of approximately 30nm. Then, the entire surface is deposited with red light CdSe quantum dots to a thickness of 30nm. Finally, the entire surface is sprayed with ZnO solution and baked at 100°C for 10 minutes to a thickness of 50nm as an electron transport layer.

[0090] Step 4: spraying a photoresist containing a PEDOT:PSS polymer, shielding it with a light shield of a specific pattern, and exposing it to solidify only the specific (unshielded) position, and developing it to prepare a patterned pixel unit.

[0091] Step 5: Clean and repeat steps 3 to 4 to complete the preparation of the three-color (red, green, and blue) full-color QD functional layer.

[0092] Step 6: Evaporate an ITO cathode layer to form a transparent electrode with a thickness of 50 nm.

[0093] Complete the production of patterned, full-color QLED devices.

[0094] The present invention innovatively reuses the photolithography cleaning method in full-color QLED devices and their preparation. On a substrate prepared with pixel isolation unit banks, a photoresist protective layer is formed by exposing photoresist at designated positions multiple times to protect the functional layer formed by inkjet printing. The unprotected area is cleaned, and a functional layer of another color is inkjet printed again, and photoresist is applied again. This process is repeated to achieve efficient preparation of full-color QLED devices with high pixel density. In addition, quantum dots do not require ligand exchange, and there is no organic polymer barrier between QDs, which does not affect the photoelectric performance and stability of QDs. The method is compatible with the traditional QLED inkjet printing preparation method and is simple.

[0095] It should be understood that the embodiments disclosed herein are not limited to the specific processing steps or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0096] The "embodiment" mentioned in the specification means that a particular feature or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0097] Although the embodiments disclosed herein are as described above, the contents described herein are merely embodiments for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art may make any modifications and variations in the form and details of the embodiments without departing from the spirit and scope of the present invention. However, the scope of protection of the present invention shall remain subject to the scope defined by the appended claims.

Claims

1. A full-color QLED device, comprising: substrate; Pixel isolation units bank, the pixel isolation units bank are distributed in an array on the substrate; A full-color QD array, wherein any QD functional unit in the full-color QD array is disposed in the pixel isolation unit bank; A photoresist protective layer, the photoresist protective layer being disposed above the full-color QD array; A transparent electrode is provided above the photoresist protection layer. The QD functional units in the full-color QD array are filled in the pixel isolation unit bank by sequential photolithography and cleaning.

2. The device according to claim 1, wherein the QD functional unit comprises, from bottom to top, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer. in, Along the length direction and / or width direction of the substrate, the colors of the quantum dot light-emitting layers in two adjacent QD functional units are different.

3. The device according to any one of claims 1 to 2, further comprising: an electron transport layer, the electron transport layer being disposed between the photoresist protection layer and the transparent electrode, or The electron transport layer is arranged between the photoresist protection layer and the full-color QD array.

4. The device according to claim 1, wherein the QD functional unit comprises an electron transport layer and a quantum dot light-emitting layer in order from bottom to top, wherein: Along the length direction and / or width direction of the substrate, the colors of the quantum dot light-emitting layers in two adjacent QD functional units are different; The device further comprises: a hole transport layer, the hole transport layer being disposed above the photoresist protection layer; A hole injection layer is provided between the hole transport layer and the transparent electrode.

5. The device according to claim 1, wherein The pixel isolation unit bank has a size of 0.1 micrometer to 2000 micrometers.

6. The device according to claim 1, wherein The material of the photoresist protection layer is a photoresist containing a hole semiconductor material.

7. A method for preparing a full-color QLED device, comprising: A plurality of pixel isolation units (banks) are prepared in an array above the substrate; Repeating photolithography and cleaning to sequentially prepare functional layers of different colors within the plurality of pixel isolation units bank; Transparent electrodes are prepared on top of functional layers of different colors. The process of preparing the functional layer by using the photolithography cleaning method at any time includes: Depositing a functional layer of a current color in the pixel isolation unit bank and applying photoresist; Using the current light shielding plate provided with patterned slits, the functional layer is shielded and exposed to light to form a photoresist protection layer above the functional layer in the unshielded area; The functional layer is cleaned, and a functional layer of the next color is re-deposited in the cleaned pixel isolation unit bank.

8. The method according to claim 7, wherein: The process of preparing the functional layer at least includes: A hole injection layer, a hole transport layer and a quantum dot light emitting layer are sequentially deposited in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light emitting layer.

9. The method according to claim 8, further comprising: An electron transport layer is deposited on top of the quantum dot light-emitting layer.

10. The method according to claim 8, further comprising: An electron transport layer is deposited between the photoresist protection layer and the transparent electrode.

11. The method according to claim 7, wherein: The process of preparing the functional layer at least includes: An electron transport layer and a quantum dot light-emitting layer are sequentially deposited in the pixel isolation unit bank, wherein the color of the functional layer is determined by the color of the quantum dot light-emitting layer.

12. The method according to claim 11, further comprising: A hole transport layer and a hole injection layer are sequentially deposited on the photoresist protection layer.

13. The method according to claim 7, wherein: The photoresist is applied by spin coating or spray coating, and the photoresist is a photoresist containing a hole semiconductor material.

14. The method according to claim 7, further comprising: The surface of the substrate on which the pixel isolation unit bank is prepared is cleaned.

15. The method according to claim 7, wherein: The patterned gaps in the light shielding plate used to shield the functional layer at any two times are different.

16. The method according to claim 7, wherein Along the length direction and / or width direction of the substrate, the functional layers in two adjacent pixel isolation units (bank) have different colors.

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