Fabrication method of light-emitting substrate, display panel and display device

Abstract

This disclosure provides a method for fabricating a light-emitting substrate, a display panel, and a display device. The method for fabricating the light-emitting substrate includes: providing a substrate, with a plurality of arrayed first electrodes disposed on one side of the substrate; the substrate includes a plurality of arrayed pixel regions, each pixel region including a plurality of sub-regions, and each first electrode located on one sub-region; on one side of the substrate, for each pixel region, sequentially forming a light-emitting device of a target color in each target sub-region; wherein the step of forming the light-emitting device of the target color in the target sub-region includes: on the side of the pixel region where the first electrodes are away from the substrate, sequentially forming a target-color light-emitting functional layer, a second electrode, and a protective sacrificial layer that cover the first electrodes of each sub-region and are integrally connected; and removing the target-color light-emitting functional layer, the second electrode, and the protective sacrificial layer from non-target sub-regions using a photolithography process; the non-target sub-regions being areas in the pixel region other than the target sub-regions.

Description

Technical Field

[0001] This disclosure relates to the field of display technology, specifically to a method for preparing a light-emitting substrate, a display panel, and a display device. Background Technology

[0002] With the development of display technology, large size and high PPI (Pixels Per Inch) have become important parameters for display devices. Among related technologies, the pixel pattern that can be formed by photolithography can reach an accuracy of about 2μm, which means that it is possible to form a display device with 5000 PPI.

[0003] The photolithography process includes the following steps: resist coating, exposure, development, etching, and cleaning. In the cleaning step, since the photoresist itself is an organic material, it dissolves organic solvents based on the principle of "like dissolves like," thus removing the remaining photoresist under the action of the organic solvent. As the above analysis shows, in the fabrication of light-emitting devices, all film layers in the light-emitting functional layer are organic materials, and the resist-removing solvent can also damage the light-emitting functional layer. In summary, during the cleaning of the resist remover (PR), the moisture generated by the organic solvent used for resist removal can cause moisture erosion of the light-emitting functional layer, thereby affecting the light-emitting effect of the device. Summary of the Invention

[0004] This disclosure provides a method for preparing a light-emitting substrate, a display panel, and a display device.

[0005] In a first aspect, the present disclosure provides a method for preparing a light-emitting substrate, comprising: providing a substrate, wherein a plurality of first electrodes arranged in an array are disposed on one side of the substrate, the substrate includes a plurality of pixel regions arranged in an array, each pixel region includes a plurality of sub-regions, and each first electrode is located on one of the sub-regions;

[0006] On one side of the substrate, for each pixel region, a light-emitting device of the target color is sequentially formed in each target sub-region. The light-emitting device includes a light-emitting functional layer of the target color and a second electrode. The colors of the light-emitting devices corresponding to multiple sub-regions in the same pixel region are different.

[0007] The steps of sequentially forming a light-emitting device of the target color in each target sub-region include:

[0008] In the pixel region and on the side of the first electrode away from the substrate, a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer of the target color are sequentially formed, covering the first electrode of each sub-region and connected as a whole; by photolithography, the light-emitting functional layer of the target color, the second electrode, and the protective sacrificial layer of the target color on the non-target sub-region are removed, the non-target sub-region being the area in the pixel region other than the target sub-region.

[0009] In some embodiments, the material of the protective sacrificial layer is acrylic or silicon nitride.

[0010] In some embodiments, the step of removing the light-emitting functional layer, the second electrode, and the protective sacrificial layer of the target color on the non-target sub-region by patterning includes:

[0011] A light-shielding pattern is formed on the side of the target sub-region where the protective sacrificial layer is away from the substrate;

[0012] Based on the light-shielding pattern, the non-target sub-region is etched to remove the light-emitting functional layer of the target color, the second electrode, and the protective sacrificial layer on the non-target sub-region.

[0013] Remove the light-blocking pattern from the target sub-region.

[0014] In some embodiments, the step of forming a light-emitting device of a target color in a target sub-region includes: forming a light-emitting device of the target color and the sacrificial protective layer in the target sub-region;

[0015] After forming a light-emitting device corresponding to the target color and the sacrificial protection layer on each of the sub-regions in the pixel area, the method further includes:

[0016] The protective sacrificial layer on each sub-region within the pixel region is removed by plasma processing.

[0017] In some embodiments, prior to the step of sequentially forming a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer covering each of the sub-regions and integrally connected, the method further includes:

[0018] A pixel defining material film is deposited on the side of the first electrode away from the substrate;

[0019] The pixel defining material film is patterned to form a pixel defining layer, the pixel defining layer including a plurality of arrayed receiving holes, each receiving hole exposing at least a portion of the first electrode.

[0020] In some embodiments, the step of sequentially forming a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer covering the first electrode of each sub-region and integrally connected, in the pixel region, and on the side of the first electrode away from the substrate, includes:

[0021] On the side of the first electrode away from the substrate and in the region corresponding to the entire pixel area, a hole injection layer, a hole transport layer, a light-emitting layer corresponding to the target color, an electron transport layer, and an electron injection layer are sequentially formed to form the light-emitting functional layer.

[0022] The second electrode is formed on the side of the light-emitting functional layer away from the substrate;

[0023] On the side of the second electrode away from the substrate, a protective sacrificial layer is formed based on a thin-film encapsulation process.

[0024] In some embodiments, after the step of removing the protective sacrificial layer by plasma processing on the protective sacrificial layer in each sub-region within the pixel region, the method further includes:

[0025] In the pixel region and on the side of the second electrode away from the substrate, a first conductive material thin film is deposited to form a first conductive layer, the first conductive layer being configured to electrically connect the second electrode in each sub-region.

[0026] In some embodiments, after the step of forming the first conductive layer, the method further includes:

[0027] An optical adjustment layer and an optical protection layer are sequentially deposited in the pixel area on the side of the first conductive layer away from the substrate.

[0028] In some embodiments, after the step of sequentially depositing an optical adjustment layer and an optical protective layer, the method further includes:

[0029] In the pixel area and on the side of the optical protective layer away from the substrate, an encapsulation layer is formed by a thin-film encapsulation process, and the surface of the encapsulation layer away from the substrate is a flat surface.

[0030] In a second aspect, embodiments of this disclosure provide a display panel including a light-emitting substrate, the light-emitting substrate being formed using the preparation method provided in the first aspect.

[0031] Thirdly, embodiments of this disclosure provide a display device, including the display panel provided in the second aspect. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 A schematic flowchart illustrating a method for fabricating a light-emitting substrate according to an embodiment of this disclosure;

[0034] Figure 2 This is a detailed flowchart illustrating step S2' provided in an embodiment of the present disclosure;

[0035] Figure 3 A schematic flowchart illustrating another method for preparing a light-emitting substrate provided in this embodiment of the present disclosure;

[0036] Figure 4 A schematic flowchart illustrating a method for fabricating a light-emitting substrate according to an embodiment of this disclosure;

[0037] Figures 5a-5e To adopt Figure 4 A schematic diagram of the structure of the intermediate product obtained by the preparation method shown.

[0038] Explanation of reference numerals in the attached figures:

[0039] Wafer substrate 10: First electrode ITO, red sub-region R, green sub-region G, blue sub-region B;

[0040] The light-emitting functional layer E consists of: hole injection layer HIL, hole transport layer HTL, electron injection layer ETL, electron transport layer EIL, red light-emitting layer rEML, green light-emitting layer gEML, and blue light-emitting layer bEML.

[0041] Second electrode M, first conductive layer M', first conductive material thin film m1, second conductive material thin film m2, third conductive material thin film m3, fourth conductive material thin film m4;

[0042] Optical adjustment layer CPL, optical protective layer LiF;

[0043] Protective sacrificial layer A, encapsulation layer B, and light-shielding pattern pr. Detailed Implementation

[0044] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0046] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0047] The light-emitting substrate includes multiple pixel units arranged in an array. Each pixel unit includes sub-pixel units of three colors: red, green, and blue. Correspondingly, each sub-pixel unit includes a light-emitting device of the corresponding color. Taking an OLED display device as an example, the light-emitting device in each sub-pixel unit includes an anode layer, a light-emitting functional layer, and a cathode layer. The light-emitting functional layer includes a hole injection layer, a hole transport layer, a light-emitting layer emitting red / green / blue light, an electron transport layer, and an electron injection layer. It should be understood that the materials of each film layer in the light-emitting functional layer are all organic materials.

[0048] Typically, OLED displays employ a side-by-side pixel arrangement to fabricate light-emitting devices of different colors. These devices are formed using masking techniques. Specifically, the masked areas on a photomask are used to block the corresponding areas of two colors within a pixel unit. Then, a film-forming material is deposited onto the unmasked color sub-pixel unit using evaporation or inkjet printing. The resulting pattern serves as the main material for the light-emitting layer of that sub-pixel unit. The same fabrication steps are then repeated to form the light-emitting layers for the other two colors, thus fabricating the entire pixel unit's light-emitting layer. Further, an integrated electron transport layer, electron injection layer, and cathode layer are formed within the pixel unit to complete the fabrication of all light-emitting devices within the pixel unit.

[0049] With the development of display technology, large size and high PPI (Pixels Per Inch) have become important parameters for display devices. At the same time, the patterned areas on the mask used to fabricate the light-emitting devices also need to be further refined, which requires the use of fine metal masks (FMMs).

[0050] However, due to issues such as mask alignment and mask blockage, display devices fabricated using FMM (Foil-Mesh Manufacturing) can only achieve a maximum PPI of 3000. At this point, photolithography has a greater advantage in forming the light-emitting devices within the display device. It has been verified that photolithography can create pixel patterns with an accuracy of approximately 2μm, meaning it can form display devices with a PPI of 5000.

[0051] Specifically, the photolithography process includes the following steps: photoresist coating, exposure, development, etching, and cleaning. Photoresist coating refers to applying photoresist (PR) onto a wafer substrate using a spin-coating method. Exposure refers to the chemical changes in the irradiated portion of the photoresist due to UV light irradiation. Development refers to the reaction and detachment of the irradiated photoresist under the action of a developer, exposing the underlying material, while the unirradiated portions remain unreacted and continue to cover the underlying material. Etching includes both dry etching and wet etching. Dry etching involves reacting the underlying material with a plasma gas to remove that material. Cleaning involves removing the unirradiated PR using an organic solvent, thereby forming a pattern.

[0052] In the aforementioned cleaning steps, since photoresist is an organic material, it dissolves in organic solvents based on the principle of "like dissolves like," thus allowing the remaining photoresist to be removed under the action of the organic solvent. As the above analysis shows, during the fabrication of light-emitting devices, all film layers in the light-emitting functional layer are organic materials; therefore, the photoresist remover solvent will also damage the light-emitting functional layer. In conclusion, during the cleaning of photoresist remover (PR), the moisture generated by the organic solvent used for removal will cause moisture erosion of the light-emitting functional layer, thereby affecting the light-emitting effect of the device.

[0053] To address at least one or more of the aforementioned technical problems, embodiments of this disclosure provide a light-emitting substrate that protects the light-emitting device with a protective sacrificial layer, thereby preventing adverse effects such as moisture erosion on the light-emitting device and ensuring the light-emitting effect of the substrate.

[0054] Figure 1 This is a schematic flowchart illustrating a method for fabricating a light-emitting substrate according to an embodiment of the present disclosure, as shown below. Figure 1 As shown, the method for preparing the light-emitting substrate includes:

[0055] Step S1: A substrate is provided, and a plurality of first electrodes arranged in an array are disposed on one side of the substrate. The substrate includes a plurality of pixel regions arranged in an array, each pixel region includes a plurality of sub-regions, and each first electrode is located on a sub-region.

[0056] It should be understood that the light-emitting devices in the light-emitting substrate of this disclosure are formed based on photolithography. The basic principle of photolithography is to use the photoresist (or photoresist) to form corrosion resistance after photochemical reaction, thereby etching the pattern on the photomask onto the surface to be processed. In order to increase the adhesion between the photoresist and the substrate, the substrate is preferably a wafer substrate.

[0057] In addition, when using wafer substrates, pretreatment of the substrate is required. For example, before applying photoresist, the cleaned substrate surface is coated with an adhesion enhancer or the substrate is heat-treated in an inert gas atmosphere. This treatment is to increase the adhesion between the photoresist and the substrate, prevent the photoresist pattern from peeling off during development, and prevent lateral etching during wet etching.

[0058] Step S2: On one side of the substrate, step S2' is performed on each pixel area: a light-emitting device of the target color is formed sequentially in each target sub-region. The light-emitting device includes a light-emitting functional layer of the target color and a second electrode. The colors of the light-emitting devices corresponding to multiple sub-regions in the same pixel area are different.

[0059] Step S2', in which a light-emitting device of the target color is formed in each target sub-region of the pixel region, includes:

[0060] Step S21: In the pixel area, on the side of the first electrode away from the substrate, a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer of the target color are sequentially formed, covering the first electrode of each sub-region and connected as a whole; Step S22: The light-emitting functional layer of the target color, the second electrode, and the protective sacrificial layer of the target color on the non-target sub-region are removed by photolithography. The non-target sub-region is the area in the pixel area other than the target sub-region.

[0061] The method for fabricating a light-emitting substrate provided in this disclosure involves sequentially forming a first electrode, a light-emitting functional layer, and a second electrode of a light-emitting device on the substrate. A protective sacrificial layer is then formed above the second electrode. This arrangement allows the protective sacrificial layer to isolate the influence of development and etching processes on the light-emitting functional layer during the patterning process when removing the film structure on the non-target sub-region using photolithography. Furthermore, since the protective sacrificial layer covers the first electrode, the light-emitting functional layer, and the second electrode of the light-emitting device, the entire structure of each light-emitting device is independently formed under the protection of the protective sacrificial layer during the sequential fabrication of each light-emitting device in the pixel region. This prevents crosstalk between the light-emitting devices and improves the light-emitting effect of the light-emitting substrate.

[0062] It should also be noted that, in one example, the pixel region comprises three sub-regions: a red sub-region containing a red light-emitting device, a green sub-region containing a green light-emitting device, and a blue sub-region containing a blue light-emitting device. The pixel region also includes multiple spacing regions, which are the areas between any two sub-regions. When fabricating a red light-emitting device, the red sub-region is the target sub-region. In this case, the non-target sub-regions include not only the green and blue sub-regions but also multiple spacing regions, such as the spacing between the red and green sub-regions, and the spacing between the green and blue sub-regions.

[0063] In some embodiments, the material of the protective sacrificial layer is acrylic acid or silicon nitride. Specifically, acrylic acid or silicon nitride is formed on the side of the second electrode away from the substrate by a thin film encapsulation (TFE) process, and a protective sacrificial layer is formed by the TFE process to block moisture or air that may cause insufficient brightness or fatal defects such as black spots in the light-emitting device, thereby ensuring the light-emitting effect of the light-emitting device.

[0064] Figure 2 This is a detailed flowchart illustrating step S2' provided in an embodiment of the present disclosure. In some embodiments, such as... Figure 2 As shown, before step S21, the above step S2' further includes step S20: depositing a pixel defining material film on the side of the first electrode away from the substrate; patterning the pixel defining material film to form a pixel defining layer, the pixel defining layer including a plurality of arrayed receiving holes, each receiving hole exposing at least a portion of the first electrode.

[0065] The pixel defining layer can be made of a polymer material that can block water vapor, such as acrylic material, to prevent water molecules and / or oxygen molecules from penetrating the interior.

[0066] In addition, the receiving holes formed in the pixel defining layer are trapezoidal in the thickness direction of the light-emitting substrate. When the pixel defining layer is fabricated, the trapezoidal shape with isotropic properties can prevent impurities from entering from the environment, thereby protecting the light-emitting device.

[0067] In some embodiments, step S22 may specifically include:

[0068] Step S220: A light-shielding pattern is formed in the target sub-region, on the side of the protective sacrificial layer away from the substrate; the non-target sub-region is etched based on the light-shielding pattern to remove the target color light-emitting functional layer, the second electrode, and the protective sacrificial layer on the non-target sub-region; the light-shielding pattern on the target sub-region is removed.

[0069] Specifically, the material of the aforementioned light-shielding pattern can be photoresist (PR). In one example, PR covering the entire pixel area is first coated over the sacrificial protective layer, and a mask is placed over the photoresist. The PR on the non-target sub-region is irradiated with UV lamp based on the mask pattern. The PR on the non-target sub-region is removed by development to expose the protective sacrificial layer on the non-target sub-region. Further, the protective sacrificial layer, the second electrode, and the light-emitting functional layer of the target color on the non-target sub-region are sequentially etched away. At this time, each film layer on the target sub-region is not affected by etching under the action of PR, so the structure of the target sub-region is preserved. Further, the PR on the target sub-region is removed under the action of an organic solvent. At this time, the protective sacrificial layer on the target sub-region covers the light-emitting device, so the water vapor generated by the organic solvent used to remove PR will not affect the light-emitting functional layer in the light-emitting device.

[0070] Figure 3 This is a schematic flowchart illustrating another method for fabricating a light-emitting substrate provided in this disclosure. In some embodiments, such as... Figure 3 As shown, after a light-emitting device and a sacrificial protective layer of the corresponding target color are formed on each sub-region in the pixel area, the method further includes step S3: performing plasma processing on the protective sacrificial layer on each sub-region in the pixel area to remove the protective sacrificial layer.

[0071] In one example, when light-emitting devices corresponding to the emitted light color are sequentially formed in each sub-region of the pixel area according to the method provided in step S2' above, although the protective sacrificial layer on each target sub-region can protect the light-emitting device it covers, a large number of particles are generated in the protective sacrificial layer retained on the target sub-region during photolithography of the protective sacrificial layer, the second electrode, and the light-emitting functional layer in the non-target sub-regions, resulting in dark spot defects on the pixel area. Based on this, the protective sacrificial layer deposited in each sub-region is removed by plasma dry etching (PLMA) process, thereby eliminating dark spot defects on the pixel area caused by particles.

[0072] In some embodiments, such as Figure 2 As shown, step S21 above may specifically include:

[0073] In step S210, a hole injection layer, a hole transport layer, a light-emitting layer corresponding to the target color, an electron transport layer, and an electron injection layer are sequentially formed on the side of the first electrode away from the substrate and in the region corresponding to the entire pixel area to form a light-emitting functional layer; a second electrode is formed on the side of the light-emitting functional layer away from the substrate; and a protective sacrificial layer is formed on the side of the second electrode away from the substrate based on a thin-film encapsulation process.

[0074] It should be understood that when current flows through the light-emitting device, holes are generated by the first electrode and electrons are generated by the second electrode. Holes are injected into the light-emitting layer through the hole injection layer and the hole transport layer, and electrons are injected into the light-emitting layer through the electron injection layer and the electron transport layer, and excitons are formed in the light-emitting layer to emit light.

[0075] In the embodiments of this disclosure, the light-emitting devices in each sub-region of the pixel region are sequentially fabricated in the accommodating portion corresponding to the pixel defining region. That is, each film layer structure in the light-emitting functional layer corresponding to each light-emitting device is formed independently, and the film layer structures included in the light-emitting functional layer of different light-emitting devices are not shared. This arrangement reduces the risk of pixel crosstalk in different sub-regions and is beneficial to improving the light-emitting effect of the light-emitting substrate.

[0076] In addition, the first electrode can be a transparent electrode made of indium tin oxide, and the second electrode can be a reflective electrode made of metal.

[0077] In some embodiments, such as Figure 3 As shown, after step S3, the method further includes step S4: depositing a first conductive material thin film in the pixel area, on the side of the second electrode away from the substrate, to form a first conductive layer, the first conductive layer being configured to electrically connect the second electrode in each sub-region.

[0078] As can be seen from the above analysis, the second electrodes formed in step S22 are arranged at intervals corresponding to each sub-region, and there is no electrical connection between two second electrodes in adjacent sub-regions. Therefore, after the protective sacrificial layer is removed by the plamasa process, a first conductive layer is formed that is integrated. The second electrodes formed independently in each sub-region and the first conductive layer stacked on top of them form an integrated conductive structure, so that each sub-region can uniformly receive voltage signals during the display stage, providing pixel voltage for each light-emitting device.

[0079] Furthermore, in step S4 above, the first conductive layer is formed directly on the side of the second electrode away from the substrate, rather than being formed only in the area between adjacent sub-regions to connect adjacent second electrodes. In this way, there is no need for patterning, saving on the fabrication process. On the other hand, the first conductive layer is stacked on top of the second electrode, which is equivalent to increasing the thickness of the second electrode, which helps to reduce the resistance on the second electrode and save driving resources.

[0080] In some embodiments, such as Figure 3 As shown, the method for preparing the light-emitting substrate further includes step S5: in the pixel area, and on the side of the first conductive layer away from the substrate, an optical adjustment layer and an optical protective layer are sequentially vapor-deposited.

[0081] The optical adjustment layer has a high refractive index to regulate light emission and form a resonant microcavity, improving the emitted light color. For example, the refractive index of the optical adjustment layer for 460nm wavelength light is greater than 1.8, thereby increasing the light emission angle and improving the light output of the light-emitting device. The optical protective layer located above the optical adjustment layer can be made of lithium fluoride (LiF). On the one hand, the optical protective layer can serve as a high-refractive-index material to improve light extraction efficiency; on the other hand, LiF material provides a certain degree of UV protection, reducing the impact of UV irradiation on the light-emitting device during subsequent processes.

[0082] In the above structure, the optical adjustment layer is located between the optical protective layer and the second electrode. Therefore, the optical adjustment layer is equivalent to inserting a medium with a relative refractive index close to the middle value between two media with a large difference in relative refractive index, in order to increase the critical angle, thereby increasing the incident angle of each medium layer, so that light that could not originally escape can be refracted out.

[0083] In some embodiments, such as Figure 3 As shown, the method for preparing the light-emitting substrate further includes step S6: in the pixel area, and on the side of the optical protective layer away from the substrate, an encapsulation layer is formed by a thin film encapsulation process, and the surface of the encapsulation layer away from the substrate is a flat surface.

[0084] It should be noted that in this embodiment, the encapsulation layer and the protective sacrificial layer are formed using the same materials and processes; that is, the encapsulation layer material includes acrylic acid or silicon nitride. However, after forming the encapsulation layer using the TFE process, there is no need for further processes such as exposure and dry etching to remove the encapsulation material from certain areas, thus preventing the presence of particles. On one hand, the encapsulation layer formed by acrylic acid or silicon nitride can prevent moisture from penetrating the interior of the light-emitting device; on the other hand, its surface away from the substrate is flat, which is beneficial for the subsequent fabrication of the structure.

[0085] The method for preparing the light-emitting substrate in this disclosure will be described in detail below with reference to the accompanying drawings and specific embodiments. Figure 4 This is a schematic flowchart illustrating a method for fabricating a light-emitting substrate according to an embodiment of the present disclosure. Figures 5a-5e To adopt Figure 4 The diagram shows the structure of the intermediate product obtained by the preparation method, which is used to prepare a light-emitting substrate. It should be noted that... Figures 5a-5e The diagram only shows the structure on one pixel region of the light-emitting substrate. This pixel region includes three sub-regions: a red sub-region R containing a red light-emitting device, a green sub-region G containing a green light-emitting device, and a blue sub-region B containing a blue light-emitting device.

[0086] like Figure 4 As shown, the method for preparing the light-emitting substrate includes steps S01-S05, as detailed below.

[0087] See Figure 5a Step S01 includes steps S101-S103, wherein:

[0088] Step S101: A wafer substrate 10 is provided, and a first electrode ITO is formed on one side of the wafer substrate 10 corresponding to the region of each sub-region.

[0089] The light-emitting device in the light-emitting substrate of this disclosure is formed by photolithography. The basic principle of photolithography is to use the photoresist (or photoresist) to form corrosion resistance after photochemical reaction, and to etch the pattern on the photomask onto the surface to be processed. Therefore, it is preferable to use a wafer substrate 10 as the substrate of the light-emitting device.

[0090] Step S102: Deposit an acrylic material thin film pdl0 on the side of the first electrode ITO away from the wafer substrate 10.

[0091] Step S103: The acrylic material thin film pdl0 is patterned using photolithography to form a pixel defining layer. The pixel defining layer includes multiple arrayed receiving holes k, and each receiving hole k exposes at least a portion of the first electrode ITO.

[0092] See Figure 5b Step S02 is used to prepare and form a red light-emitting device, specifically including steps S201-S205, wherein:

[0093] Step S201: Sequentially deposit the hole injection layer HIL, the hole transport layer HTL, the red-emitting layer rEML, the electron transport layer EIL, and the electron injection layer ETL on the pixel area.

[0094] In the above steps, each film layer is an organic material layer to form an organic light-emitting functional layer E.

[0095] Step S202: Deposit a second conductive material thin film m2 on the electron injection layer ETL.

[0096] In step S203, acrylic material or silicon oxide material is deposited on the second conductive material film m2 using a TFE process to form a protective sacrificial layer A.

[0097] Step S204: Coat the protective sacrificial layer A with PR material. After exposure and development, remove the portion of the area outside the red sub-region R, leaving only the PR on the red sub-region R to form the light-shielding pattern pr.

[0098] Step S205 involves removing the hole injection layer HIL, hole transport layer HTL, red-emitting layer rEML, electron transport layer EIL, electron injection layer ETL, and second conductive material film m2 from the area outside the red sub-region R using a dry etching process, and cleaning the light-shielding pattern pr on the red sub-region R.

[0099] At this time, a red light-emitting device is formed on the red sub-region R, and only the second conductive material thin film m2 on the red sub-region R is retained as the second electrode M of the red light-emitting device.

[0100] When forming a red light-emitting device, each film layer on the red sub-region R is not affected by etching under the action of PR, so the structure of the red sub-region R is preserved. Furthermore, the PR on the red sub-region R is removed under the action of organic solvent. At this time, the protective sacrificial layer A on the red sub-region R covers the light-emitting device. Therefore, the water vapor generated by the organic solvent used to remove PR will not affect the light-emitting functional layer E in the light-emitting device.

[0101] Furthermore, based on the same inventive concept as that used to prepare a red light-emitting device in the red sub-region R, a green light-emitting device is prepared in the green sub-region G and a blue light-emitting device is prepared in the blue sub-region B.

[0102] See Figure 5c Step S03 is used to prepare and form a green light-emitting device, specifically including steps S301-S305, wherein:

[0103] Step S301: Sequentially deposit a hole injection layer HIL, a hole transport layer HTL, a green light-emitting layer g, an electron transport layer EIL, and an electron injection layer ETL on the pixel area.

[0104] Step S302: Deposit a third conductive material thin film m3 on the electron injection layer ETL.

[0105] In step S303, acrylic material or silicon oxide material is deposited on the third conductive material thin film m3 by TFE process to form a protective sacrificial layer A.

[0106] Step S304: Coat the protective sacrificial layer A with PR material. After exposure and development, remove the portion of the area outside the green sub-region G, leaving only the PR on the green sub-region G to form the light-shielding pattern pr.

[0107] In step S305, the hole injection layer HIL, hole transport layer HTL, green light-emitting layer gEML, electron transport layer EIL, electron injection layer ETL, and third conductive material film m3 on the area outside the green sub-region G are removed by dry etching. The light-shielding pattern pr on the green sub-region G is also cleaned. At this point, a green light-emitting device is formed on the green sub-region G, with only the third conductive material film m3 remaining on the green sub-region G as the second electrode M of the green light-emitting device.

[0108] See Figure 5d Step S04 is used to prepare and form a blue light-emitting device, specifically including steps S401-S405, wherein:

[0109] Step S401: Sequentially deposit the hole injection layer HIL, the hole transport layer HTL, the light-emitting layer bEML with blue light emission color, the electron transport layer EIL, and the electron injection layer ETL on the pixel area.

[0110] Step S402: Deposit a fourth conductive material thin film m4 on the electron injection layer ETL.

[0111] In step S403, acrylic material or silicon oxide material is deposited on the fourth conductive material thin film m4 using a TFE process to form a protective sacrificial layer A.

[0112] Step S404: Coat the protective sacrificial layer A with PR material. After exposure and development, remove the portion of the area outside the blue sub-region B, leaving only the PR on the blue sub-region B to form the light-shielding pattern PR.

[0113] In step S405, the hole injection layer HIL, hole transport layer HTL, blue light-emitting layer b, electron transport layer EIL, electron injection layer ETL, and fourth conductive material film m4 on the area outside the blue sub-region B are removed by a dry etching process. The light-shielding pattern pr on the blue sub-region B is also cleaned. At this point, a blue light-emitting device is formed on the blue sub-region B, with only the fourth conductive material film m4 remaining on the blue sub-region B as the second electrode M of the blue light-emitting device.

[0114] See Figure 5e Step S05 includes steps S501-S504, wherein:

[0115] Step S501: Remove the protective sacrificial layer A in each sub-region using a plasma process.

[0116] Although the protective sacrificial layer A on each target sub-region can protect the light-emitting device it covers, the photolithography process on the protective sacrificial layer A, the second electrode M, and the light-emitting functional layer E in non-target sub-regions generates a large number of particles in the protective sacrificial layer A retained on the target sub-region, resulting in dark spot defects on the pixel area. Therefore, by using a plasma dry etching (PLMA) process to remove the protective sacrificial layer A deposited in each sub-region, the dark spot defects caused by particles on the pixel area can be eliminated.

[0117] Step S502: Deposit a first conductive material thin film m1 to form a first electrode layer M'.

[0118] In step S503, an optical adjustment layer CPL and an optical protective layer LiF are sequentially formed on the first electrode layer M'.

[0119] The optical adjustment layer (CPL) is used to increase the emission angle of light and improve the light output of the light-emitting device. The optical protective layer (LiF) located above the CPL can be made of lithium fluoride (LiF). On the one hand, the LiF optical protective layer can serve as a high-refractive-index material to improve light extraction efficiency; on the other hand, LiF provides a certain degree of UV protection, which can reduce the impact of UV irradiation on the light-emitting device in subsequent processes.

[0120] In step S504, acrylic acid or silicon oxide is deposited on the optical protective layer LiF using the TFE process to form the encapsulation layer B.

[0121] In the method for fabricating a light-emitting substrate provided in this embodiment, after sequentially forming a first electrode ITO, a light-emitting functional layer E, and a second electrode M on the substrate, a protective sacrificial layer A is formed above the second electrode M. This arrangement allows the protective sacrificial layer A to isolate the influence of development and etching processes on the light-emitting functional layer E during the patterning process when removing the film structure on the non-target sub-region via photolithography. Furthermore, since the protective sacrificial layer A covers the first electrode ITO, the light-emitting functional layer E, and the second electrode M, the entire structure of each light-emitting device in the pixel region is independently formed under the coverage of the protective sacrificial layer A during the sequential fabrication of each device. This prevents crosstalk between the light-emitting devices and improves the light-emitting effect of the substrate.

[0122] In addition, it should be noted that the material thickness of all the above-mentioned film layers can be flexibly adjusted by those skilled in the art, and this disclosure does not limit this aspect.

[0123] Based on the same inventive concept, this disclosure also provides a display panel, including a light-emitting substrate prepared by the preparation method provided in any of the above embodiments.

[0124] This disclosure also provides a display device, including the above-described display panel.

[0125] The aforementioned display device can be any product or component with display function, such as electronic paper, mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigator, and this disclosure does not limit it.

[0126] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for manufacturing a light-emitting substrate, characterized by, The method includes: A substrate is provided, wherein a plurality of first electrodes are arranged in an array on one side of the substrate, the substrate includes a plurality of pixel regions arranged in an array, each pixel region includes a plurality of sub-regions, and each first electrode is located on one of the sub-regions. On one side of the substrate, for each pixel region, a light-emitting device of the target color is sequentially formed in each target sub-region. The light-emitting device includes a light-emitting functional layer of the target color and a second electrode. The colors of the light-emitting devices corresponding to multiple sub-regions in the same pixel region are different. The steps of sequentially forming a light-emitting device of the target color in each target sub-region include: In the pixel region and on the side of the first electrode away from the substrate, a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer of the target color are sequentially formed, covering the first electrode of each sub-region and connected as a whole; by photolithography, the light-emitting functional layer of the target color, the second electrode, and the protective sacrificial layer of the target color on the non-target sub-region are removed, the non-target sub-region being the area in the pixel region other than the target sub-region.

2. The method of claim 1, wherein the light-emitting substrate is prepared by a method comprising: The material of the protective sacrificial layer is acrylic or silicon nitride. ​ 3. The method for preparing a light-emitting substrate according to claim 1, characterized in that, The step of removing the light-emitting functional layer, the second electrode, and the protective sacrificial layer of the target color from the non-target sub-region through patterning processing includes: A light-shielding pattern is formed on the side of the target sub-region where the protective sacrificial layer is away from the substrate; Based on the light-shielding pattern, the non-target sub-region is etched to remove the light-emitting functional layer of the target color, the second electrode, and the protective sacrificial layer on the non-target sub-region. Remove the light-blocking pattern from the target sub-region.

4. The method for preparing a light-emitting substrate according to claim 1, characterized in that, The step of forming a light-emitting device of a target color in a target sub-region includes: forming a light-emitting device of the target color and a sacrificial protective layer in the target sub-region; After forming a light-emitting device corresponding to the target color and the sacrificial protection layer on each of the sub-regions in the pixel area, the method further includes: The protective sacrificial layer on each sub-region within the pixel region is removed by plasma processing.

5. The method for preparing a light-emitting substrate according to claim 1, characterized in that, Before the step of sequentially forming a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer covering each of the sub-regions and integrally connected, the method further includes: A pixel defining material film is deposited on the side of the first electrode away from the substrate; The pixel defining material film is patterned to form a pixel defining layer, the pixel defining layer including a plurality of arrayed receiving holes, each receiving hole exposing at least a portion of the first electrode.

6. The method for preparing a light-emitting substrate according to claim 1, characterized in that, The step of sequentially forming a light-emitting functional layer of the target color, a second electrode, and a protective sacrificial layer covering the first electrode of each sub-region and integrally connected, in the pixel region, and on the side of the first electrode away from the substrate, includes: On the side of the first electrode away from the substrate and in the region corresponding to the entire pixel area, a hole injection layer, a hole transport layer, a light-emitting layer corresponding to the target color, an electron transport layer, and an electron injection layer are sequentially formed to form the light-emitting functional layer. The second electrode is formed on the side of the light-emitting functional layer away from the substrate; On the side of the second electrode away from the substrate, a protective sacrificial layer is formed based on a thin-film encapsulation process.

7. The method for preparing a light-emitting substrate according to claim 4, characterized in that, After the step of removing the protective sacrificial layer by plasma processing on the protective sacrificial layer in each sub-region within the pixel region, the method further includes: In the pixel region and on the side of the second electrode away from the substrate, a first conductive material thin film is deposited to form a first conductive layer, the first conductive layer being configured to electrically connect the second electrode in each sub-region.

8. The method for preparing a light-emitting substrate according to claim 7, characterized in that, After the step of forming the first conductive layer, the method further includes: An optical adjustment layer and an optical protection layer are sequentially deposited in the pixel area on the side of the first conductive layer away from the substrate.

9. The method for preparing a light-emitting substrate according to claim 8, characterized in that, After the steps of sequentially depositing an optical adjustment layer and an optical protective layer, the method further includes: In the pixel area and on the side of the optical protective layer away from the substrate, an encapsulation layer is formed by a thin-film encapsulation process, and the surface of the encapsulation layer away from the substrate is a flat surface.

10. A display panel, characterized in that, It includes a light-emitting substrate, which is formed using the preparation method described in any one of claims 1-9.

11. A display device, characterized in that, Includes the display panel as described in claim 10.

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