OLED display panel and preparation method thereof

Abstract

The present invention provides a method for preparing an OLED display panel, the method comprising: step S1, providing a substrate, the substrate comprising TFT devices arranged in an array, anodes arranged in an array on the substrate, the anodes being electrically connected to the TFT devices; an auxiliary layer being arranged on the anodes; step S2, forming a pixel definition layer on the substrate, the anodes and the auxiliary layer being arranged in a pixel opening of the pixel definition layer; step S3, removing the auxiliary layer in the pixel opening and dust particles accidentally falling on the auxiliary layer, and then preparing a light-emitting material layer and a cathode layer in the pixel opening; since the present invention reduces the risk of organic particles contaminating the surface of the anode during the process, the risk of a short circuit between the cathode and the anode in the OLED device is avoided, the probability of dark spots and vanishing spots is reduced, thereby improving the display quality of the display panel.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to an OLED display panel and a method for preparing the same. Background Art

[0002] Organic Light Emitting Display (OLED) has many advantages such as self-luminescence, low driving voltage, high luminous efficiency, short response time, high clarity and contrast, nearly 180° viewing angle, wide operating temperature range, flexible display and large-area full-color display, etc. It is recognized by the industry as the display device with the most development potential.

[0003] OLED display panels usually include: a substrate, an anode arranged on the substrate, a hole injection layer arranged on the anode, a hole transport layer arranged on the hole injection layer, a light-emitting layer arranged on the hole transport layer, an electron transport layer arranged on the light-emitting layer, an electron injection layer arranged on the electron transport layer, and a cathode arranged on the electron injection layer. The light-emitting principle of OLED display devices is that semiconductor materials and organic light-emitting materials emit light through carrier injection and recombination under the drive of an electric field. Specifically, OLED display devices usually use ITO pixel electrodes and metal electrodes as the anode and cathode of the device respectively. Under a certain voltage drive, electrons and holes are injected from the cathode and anode into the electron transport layer and the hole transport layer respectively. Electrons and holes migrate to the light-emitting layer through the electron transport layer and the hole transport layer respectively, and meet in the light-emitting layer to form excitons and excite the light-emitting spectra. The latter emits visible light after radiation relaxation.

[0004] like Figure 1 As shown, since the pixel definition layer in the OLED display panel is formed by curing a hydrophobic material solution, there are ink droplets falling onto the anode 11 during the inkjet printing and curing process, and the organic particles of the residual pixel definition layer will cause particles on the surface of the anode. After magnification by OM (optical microscope) or SEM (scanning electron microscope), it is found that the foreign protruding particles 12 appear as small black spots in the early stage. Figure 2 As shown, after the light-emitting device in the OLED display panel is prepared, during the high temperature and high pressure test, the protruding foreign particles 12 cause the anode and cathode at that position to short-circuit, and the light-emitting device 13 here does not emit light, affecting the display quality of the display panel, which needs to be improved. Summary of the invention

[0005] Based on the existing technical problems, the present application provides an OLED display panel and a preparation method thereof, which can solve the technical problem in the prior art that in the preparation process of the OLED display panel, when ink droplets of a hydrophobic material solution whose pixel definition layer falls onto the anode, the residual organic particles on the surface will cause a short circuit between the cathode and the anode, which will initially appear as small black spots and later form vanishing spots.

[0006] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0007] An embodiment of the present invention provides a method for preparing an OLED display panel, the method comprising:

[0008] Step S1, providing a substrate, wherein the substrate includes TFT devices arranged in an array, anodes are arranged in an array on the substrate, and the anodes are electrically connected to the TFT devices; and an auxiliary layer is arranged on the anodes;

[0009] Step S2, forming a pixel definition layer on the substrate, wherein the anode and the auxiliary layer are arranged in a pixel opening of the pixel definition layer;

[0010] Step S3, removing the auxiliary layer located in the pixel opening and dust particles accidentally falling on the auxiliary layer, and then preparing a light-emitting material layer and a cathode layer in the pixel opening.

[0011] According to a preferred embodiment of the present invention, step S1 specifically includes: step S11, sputtering and depositing a transparent ITO layer on the surface of the substrate as an anode layer; depositing a metal layer on the anode layer; step S12, etching the metal layer to form a required auxiliary layer, and using the auxiliary layer as a barrier layer, further etching the anode layer to form the required anode.

[0012] According to a preferred embodiment of the present invention, the material of the metal layer is copper, the material for etching the metal layer is cupric acid, and the material for etching the anode layer is silver acid.

[0013] According to a preferred embodiment of the present invention, the auxiliary layers are distributed in a grid shape; viewed from the light emitting direction of the OLED display panel, the auxiliary layers are all located on the anode and do not exceed the boundary of the anode.

[0014] According to a preferred embodiment of the present invention, in step S3, copper acid is used to perform full-surface etching to remove the auxiliary layer and residual dust particles thereon.

[0015] According to a preferred embodiment of the present invention, the dust particles that fall on the auxiliary layer by mistake are hydrophobic materials of the pixel definition layer; the hydrophobic material is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0016] According to a preferred embodiment of the present invention, the auxiliary layer in step S1 is a transparent ITO material layer.

[0017] According to a preferred embodiment of the present invention, the auxiliary layer in step S1 is a polymer conductive film.

[0018] According to a preferred embodiment of the present invention, the TFT device in step S1 includes a substrate, a light-shielding layer located on the substrate and a buffer layer covering the light-shielding layer, an active layer located on the buffer layer, a gate located on the active layer and an interlayer insulating layer covering the gate, a source and a drain located on the interlayer insulating layer, and a planarization layer located on the source and the drain, the anode is electrically connected to the drain through a via hole in the planarization layer; wherein the drain is also electrically connected to the light-shielding layer through via holes in the interlayer insulating layer and the buffer layer.

[0019] According to the method for manufacturing a display panel of the above embodiment, the present invention further provides a display panel, and the display panel is manufactured by the method for manufacturing a display panel of the above embodiment.

[0020] Beneficial effects of the present invention: An embodiment of the present invention provides a method for preparing an OLED display panel, the method comprising: step S1, providing a substrate, the substrate comprising TFT devices arranged in an array, anodes arranged in an array on the substrate, the anodes being electrically connected to the TFT devices; an auxiliary layer being arranged on the anodes; step S2, forming a pixel definition layer on the substrate, the anodes and the auxiliary layer being arranged in a pixel opening of the pixel definition layer; step S3, removing the auxiliary layer in the pixel opening and dust particles accidentally falling on the auxiliary layer, and then preparing a light-emitting material layer and a cathode layer in the pixel opening. Since the present invention reduces the risk of organic particles contaminating the surface of the anode during the process, the risk of short circuits between the cathode and the anode in the OLED device is avoided, and the probability of dark spots and vanishing spots is reduced, thereby improving the display quality of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 and Figure 2 This is an enlarged schematic diagram of organic particles remaining on the anode of a conventional OLED display panel.

[0023] Figures 3 to 16 The present invention provides a structural schematic diagram of a preparation process of an OLED display panel. DETAILED DESCRIPTION

[0024] The following descriptions of the embodiments are made with reference to the attached diagrams to illustrate specific embodiments in which the present invention may be implemented. The directional terms mentioned in the present invention, such as [up], [down], [front], [back], [left], [right], [inside], [outside], [side], etc., are only with reference to the directions of the attached diagrams. Therefore, the directional terms used are used to illustrate and understand the present invention, rather than to limit the present invention. In the figures, units with similar structures are represented by the same reference numerals, and the dotted lines in the figures represent those that do not exist in the structure and only illustrate the shape and position of the structure.

[0025] The present invention aims to solve the technical problem in the prior art that in the preparation process of OLED display panels, when ink drops of a hydrophobic material solution in the pixel definition layer fall onto the anode, the residual organic particles on the surface will cause a short circuit between the cathode and the anode, which will initially appear as small black spots and later form vanishing spots. The present invention can solve the above technical defects.

[0026] In order to solve the above technical problems, an embodiment of the present invention provides a method for preparing an OLED display panel, the method comprising: step S1, providing a substrate, the substrate comprising an array of TFT devices, an array of anodes on the substrate, the anodes being electrically connected to the TFT devices; an auxiliary layer being arranged on the anodes; step S2, forming a pixel definition layer on the substrate, the anodes and the auxiliary layer being arranged in a pixel opening of the pixel definition layer; step S3, removing the auxiliary layer in the pixel opening and dust particles that fall on the auxiliary layer by mistake, and then preparing a light-emitting material layer and a cathode layer in the pixel opening. Since the present invention reduces the risk of organic particles contaminating the surface of the anode during the process, the risk of short circuits between the cathode and the anode in the OLED device is avoided, and the probability of dark spots and vanishing spots is reduced, thereby improving the display quality of the display panel.

[0027] Preferably, step S1 specifically includes: step S11, sputtering and depositing a transparent ITO layer on the surface of the substrate as an anode layer; depositing a metal layer on the anode layer; step S12, etching the metal layer to form a required auxiliary layer, and using the auxiliary layer as a barrier layer, further etching the anode layer to form a required anode. Preferably, the material of the metal layer is copper, the material for etching the metal layer is cupric acid, and the material for etching the anode layer is silver acid. Preferably, the auxiliary layers are distributed in a grid shape; viewed from the light emitting direction of the OLED display panel, the auxiliary layers are all located on the anode and do not exceed the boundary of the anode. Preferably, in step S3, cupric acid is used to etch the entire surface to remove the auxiliary layer and residual dust particles thereon.

[0028] Preferably, the dust particles that fall on the auxiliary layer by mistake are hydrophobic materials of the pixel definition layer; the hydrophobic material is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. Preferably, the auxiliary layer in step S1 is a transparent ITO material layer. Preferably, the auxiliary layer in step S1 is a polymer conductive film.

[0029] The base of the OLED display panel in the present invention includes an array-arranged TFT device, which includes a substrate, a light-shielding layer located on the substrate and a buffer layer covering the light-shielding layer, an active layer located on the buffer layer, a gate located on the active layer and an interlayer insulating layer covering the gate, a source and a drain located on the interlayer insulating layer, and a planarization layer located on the source and the drain, the anode is electrically connected to the drain through a via hole in the planarization layer; the drain is also electrically connected to the light-shielding layer through signal vias in the interlayer insulating layer and the buffer layer.

[0030] Specifically, Figures 3 to 16 The present invention provides a structural schematic diagram of the preparation process of an OLED display panel. In step S1, the substrate includes TFT devices arranged in an array, such as Figure 3 As shown, a substrate 101 is provided. The substrate 101 is usually a glass substrate, but can also be a substrate of other materials, which is not limited here. A metal layer is deposited on the substrate 101 as a light shielding layer 102. For example, the material of the light shielding layer 102 is copper (Cu), aluminum (Al), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), chromium (Cr), etc. Figure 4 As shown, a buffer layer 103 covering the light shielding layer 102 is prepared on the substrate 101, wherein the buffer layer 103 is a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or a composite film formed by alternately stacking silicon oxide films and silicon nitride films. Figure 5 As shown, an active layer 104 is prepared on the buffer layer 103, and the material of the active layer 104 is one or more materials selected from indium gallium zinc oxide, indium zinc tin oxide, and indium gallium zinc tin oxide; the active layer 104 is deposited on the buffer layer 103 by a method selected from magnetron sputtering, metal organic chemical vapor deposition, or pulsed laser evaporation. After the active layer 104 is deposited, an annealing treatment is performed, and the annealing treatment can be performed at 400° C. in a dry air atmosphere for about 0.5 hours. After the annealing treatment is completed, the active layer 104 is etched by a wet etching process or a dry etching process using oxalic acid as an etching solution. After the etching process, the entire metal oxide film of the active layer 104 is patterned to form an island-shaped metal oxide semiconductor layer.

[0031] like Figure 6As shown, a gate insulating layer 105 is formed on the active layer 104, and a gate electrode 106 is formed on the gate insulating layer 105, wherein the material of the gate insulating layer 105 is generally silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiON), or a sandwich structure of the three; the material of the gate electrode 106 is a metal material, such as copper (Cu), aluminum (Al), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), chromium (Cr), etc. The gate electrode 106 is formed on the gate insulating layer 105 by a physical vapor deposition method, and then a photolithography process is performed to form a gate pattern.

[0032] like Figure 7 and Figure 8 As shown, an interlayer dielectric layer 107 covering the gate 106 and the active layer 104 is prepared on the buffer layer 103, and the interlayer dielectric layer 107 is preferably made of an inorganic insulating material. A signal via is opened on the interlayer dielectric layer 107 and the buffer layer 103 corresponding to the light shielding layer 102 using a fluorine-based oxidizing gas, a source contact hole is opened on the interlayer dielectric layer 107 corresponding to the source doping region using a fluorine-based oxidizing gas, and a drain contact hole is opened on the interlayer dielectric layer 107 corresponding to the drain doping region using a fluorine-based oxidizing gas. A source 108 and a drain 109 are prepared on the interlayer dielectric layer 107, wherein the source 108 is electrically connected to the source doping region through the source contact hole in the interlayer dielectric layer 107, and the drain 109 is electrically connected to the drain doping region through the drain contact hole in the interlayer dielectric layer 107, and at the same time, the drain 109 and the light shielding layer 102 are electrically connected through the signal via.

[0033] like Fig. 9 As shown, a planarization layer 110 covering the source 108 and the drain 109 is prepared on the interlayer dielectric layer 107 , and a pattern of the planarization layer 110 is formed by a wet etching process, using an oxalic acid-based solution as an etchant for the planarization layer 110 .

[0034] Figures 10 to 16 FIG. 1 is a schematic diagram of the structure of preparing an OLED light-emitting device on a substrate according to the present invention. Fig.10 and Fig.11 As shown, an anode layer 111 is deposited on the planarization layer 110, and an auxiliary layer 112 is deposited on the anode layer 111. Fig.12 and Fig.13 As shown, the auxiliary layer 112 is etched to form the required auxiliary layer 113, and the anode layer 111 is further etched to form the required anode 114. The material of the anode 114 is preferably transparent ITO, the auxiliary layer 113 is preferably copper, the material for etching the auxiliary layer 112 is copper acid, and the material for etching the anode layer 111 is silver acid. The auxiliary layer 113 of this example is distributed in a grid shape; from the light emitting direction of the OLED display panel, the auxiliary layer 113 is all located on the anode 114 and does not exceed the boundary of the anode 114.

[0035] like Fig.14 As shown, a pixel definition layer is formed on the substrate, the anode 114 and the auxiliary layer 113; the thickness of the pixel definition layer is 3μm-5μm, and the solvent of the hydrophobic material solution of the pixel definition layer is at least one of N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide. Pixel openings are formed on the pixel definition layer corresponding to the multiple anodes and on the auxiliary layer 113 located on the multiple anodes 114; for example, pixel definition layer 115 and pixel definition layer 116. Fig.15 and Fig.16 As shown, the auxiliary layer 113 and the particles covering it in the pixel opening are removed, and then the light-emitting material layer 117 and the cathode layer 118 are sequentially prepared in the pixel opening. In other embodiments, the anode 114 can also be a light-shielding metal, such as copper and molybdenum; the cathode layer 118 is preferably a transparent metal, such as an ITO electrode. The light-emitting device in the pixel opening of this embodiment also includes a hole injection layer and a hole transport layer located between the anode 114 and the light-emitting material layer 117, and an electron transport layer and an electron injection layer located between the light-emitting material layer 117 and the cathode layer 118.

[0036] According to the method for preparing the OLED display panel in the above embodiment, the present invention further provides an OLED display panel, which is prepared by the method for preparing the display panel in the above embodiment.

[0037] The present invention provides a method for preparing an OLED display panel, the method comprising: step S1, providing a substrate, the substrate comprising an array of TFT devices, an array of anodes on the substrate, the anodes being electrically connected to the TFT devices; an auxiliary layer being arranged on the anodes; step S2, forming a pixel definition layer on the substrate, the anodes and the auxiliary layer being arranged in a pixel opening of the pixel definition layer; step S3, removing the auxiliary layer in the pixel opening and dust particles that fall on the auxiliary layer by mistake, and then preparing a light-emitting material layer and a cathode layer in the pixel opening. Since the present invention reduces the risk of organic particles contaminating the surface of the anode during the process, the risk of short circuits between the cathode and the anode in the OLED device is avoided, and the probability of dark spots and vanishing spots is reduced, thereby improving the display quality of the display panel.

[0038] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for preparing an OLED display panel, characterized in that: The method comprises: Step S1, providing a substrate, wherein the substrate includes TFT devices arranged in an array, anodes are arranged in an array on the substrate, and the anodes are electrically connected to the TFT devices; and an auxiliary layer is arranged on the anodes; Step S2, forming a pixel definition layer on the substrate, wherein the anode and the auxiliary layer are arranged in a pixel opening of the pixel definition layer; Step S3, removing the auxiliary layer located in the pixel opening and dust particles accidentally falling on the auxiliary layer, and then preparing a light-emitting material layer and a cathode layer in the pixel opening; Step S1 specifically includes: step S11, sputtering and depositing a transparent ITO layer on the surface of the substrate as an anode layer; depositing a metal layer on the anode layer; step S12, etching the metal layer to form a required auxiliary layer, and using the auxiliary layer as a barrier layer, further etching the anode layer to form a required anode; The material of the metal layer is copper, the material for etching the metal layer is copper acid, and the material for etching the anode layer is silver acid; In step S3, copper acid is used to etch the entire surface to remove the auxiliary layer and the residual dust particles thereon.

2. The method for preparing an OLED display panel according to claim 1, characterized in that: The auxiliary layers are distributed in a grid shape; when viewed from the light emitting direction of the OLED display panel, the auxiliary layers are all located on the anode and do not exceed the boundary of the anode.

3. The method for preparing an OLED display panel according to claim 1, characterized in that: The dust particles that fall on the auxiliary layer by mistake are the hydrophobic material of the pixel definition layer; the hydrophobic material is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

4. The method for preparing an OLED display panel according to claim 1, wherein: The auxiliary layer in step S1 is a transparent ITO material layer.

5. The method for preparing an OLED display panel according to claim 1, characterized in that: The auxiliary layer in step S1 is a polymer conductive film.

6. The method for preparing an OLED display panel according to claim 1, characterized in that: The TFT device in step S1 includes a substrate, a light shielding layer located on the substrate and a buffer layer covering the light shielding layer, an active layer located on the buffer layer, a gate located on the active layer and an interlayer insulating layer covering the gate, a source and a drain located on the interlayer insulating layer, and a planarization layer located on the source and the drain, and the anode is electrically connected to the drain through a via hole in the planarization layer; The drain electrode is also electrically connected to the light shielding layer through the signal via holes of the interlayer insulating layer and the buffer layer.

7. An OLED display panel, characterized in that: The OLED display panel is manufactured by the method for manufacturing an OLED display panel according to any one of claims 1 to 6.

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