CN112164765A - Display panel and manufacturing method - Google Patents

Abstract

The invention provides a display panel and a manufacturing method thereof, wherein the manufacturing method comprises the following steps: manufacturing a pixel definition layer on a substrate, and manufacturing a hole on the pixel definition layer, wherein the hole on the pixel definition layer is used for accommodating a light emitting layer; manufacturing a viscosity-reducing strippable film layer, wherein the viscosity-reducing strippable film layer covers a non-hole area on the pixel defining layer; manufacturing a light emitting layer in the hole on the pixel defining layer by an ink jet printing technology; and removing the viscosity-reducing strippable film layer. The technical scheme can effectively improve the display effect and quality of the display panel and endow the display panel with greater advantages.

Description

Display panel and manufacturing method

Technical Field

The invention relates to the technical field of display, in particular to a display panel and a manufacturing method thereof.

Background

Compared with passive light emitting technology, active light emitting organic electroluminescent technology has many advantages, such as wider viewing angle, self-luminescence without backlight source, reaction time block, high light emitting efficiency, wide color gamut, low operating voltage, etc., and is called as "future final display". The principle of electroluminescence is as follows: by applying a forward voltage, holes and electrons overcome the energy barrier of the interface, and are injected from the anode and the cathode respectively, and under the driving of an external electric field, the electrons and the holes are finally recombined in the organic matter with the light-emitting characteristic to form excitons.

The organic electroluminescent diode display panel comprises a pixel definition layer for defining pixels, holes are arranged on the pixel definition layer, and the holes on the pixel definition layer are used for filling organic light-emitting function layer materials. The existing organic light-emitting functional layer materials have a plurality of preparation modes, such as vacuum thermal evaporation, ink-jet printing, laser thermal transfer imaging technology and the like. When the inkjet printing technology is adopted to prepare the organic light-emitting functional material, due to the precision problem of the inkjet printing equipment, the organic light-emitting functional material cannot be accurately printed in the holes on the pixel definition layer, and the phenomenon of bridging is caused. Meanwhile, as the display field has higher requirements on the picture quality and higher display resolution, and the pixels (holes on the pixel definition layer) are smaller and smaller, the phenomenon of 'bridging' is more and more serious.

Disclosure of Invention

Therefore, it is desirable to provide a display panel and a manufacturing method thereof, which solve the problem that the light-emitting layer cannot be accurately manufactured in the hole on the pixel defining layer by using the inkjet printing technology.

In order to achieve the above object, this embodiment provides a method for manufacturing a display panel, including the following steps:

manufacturing a pixel definition layer on a substrate, and manufacturing a hole on the pixel definition layer, wherein the hole on the pixel definition layer is used for accommodating a light emitting layer;

manufacturing a viscosity-reducing strippable film layer, wherein the viscosity-reducing strippable film layer covers a non-hole area on the pixel defining layer;

manufacturing a light emitting layer in the hole on the pixel defining layer by an ink jet printing technology;

and removing the viscosity-reducing strippable film layer.

Further, the specific steps for removing the viscosity-reducing strippable film layer are as follows:

the viscosity-reducing peelable film layer is heating viscosity-reducing glue, and the heating viscosity-reducing glue is subjected to heating treatment to reduce the viscosity of the heating viscosity-reducing glue;

and stripping the heating and viscosity reducing glue from the pixel defining layer.

Further, the specific steps for removing the viscosity-reducing strippable film layer are as follows:

the anti-adhesion peelable film layer is UV anti-adhesion glue, and the UV anti-adhesion glue is irradiated by UV light and used for weakening the adhesion of the heating anti-adhesion glue;

the UV subtractive adhesive is peeled from the pixel defining layer.

Further, the specific steps of manufacturing the anti-sticking peelable film layer are as follows:

the viscosity-reducing strippable film layer is manufactured in an ink-jet printing or evaporation mode.

Further, before the pixel definition layer is manufactured on the substrate, the method further comprises the following steps:

manufacturing a thin film transistor on a substrate;

manufacturing a planarization layer, and manufacturing a hole on the planarization layer, wherein the bottom of the hole on the planarization layer is a source electrode or a drain electrode of the thin film transistor;

manufacturing an anode layer, wherein the anode layer is connected with a source electrode or a drain electrode through a hole in the planarization layer;

the pixel definition layer is disposed on the anode layer and the planarization layer, and a bottom of the hole on the pixel definition layer is an anode.

Further, after removing the viscosity-reducing strippable film layer, the method also comprises the following steps:

manufacturing an isolation column in a non-hole area on the pixel definition layer;

and manufacturing a cathode layer.

Further, the method also comprises the following steps:

manufacturing a first inorganic layer on the cathode layer;

manufacturing an organic layer;

a second inorganic layer is fabricated.

Further, when the thin film transistor is manufactured on the substrate, the method further comprises the following steps:

and manufacturing a scanning line and a data line, wherein the scanning line is connected with the grid electrode of the thin film transistor, and the data line is connected with the source electrode of the thin film transistor.

The embodiment also provides a display panel, and the display panel is manufactured by the manufacturing method of the display panel in any one of the above embodiments.

Different from the prior art, according to the technical scheme, the viscosity-reducing strippable film layer is manufactured in the non-porous area of the pixel defining layer, and the organic light-emitting functional material printed on the viscosity-reducing strippable film layer can be stripped and removed together with the viscosity-reducing strippable film layer in the subsequent step, so that the phenomenon of bridging of the organic light-emitting functional material in the non-porous area of the pixel defining layer is avoided. The cost for manufacturing the anti-sticking strippable film layer is low, the process steps are not complicated, the display effect and the quality of the display panel can be effectively improved, and the display panel is endowed with greater advantages.

Drawings

Fig. 1 is a flow chart of a manufacturing process of the display panel according to the present embodiment;

FIG. 2 is a schematic cross-sectional view illustrating a thin film transistor array and a planarization layer formed on a substrate according to the present embodiment;

FIG. 3 is a schematic cross-sectional view illustrating an anode layer formed on a substrate according to the present embodiment;

FIG. 4 is a schematic cross-sectional view illustrating a pixel definition layer formed on a substrate according to the present embodiment;

FIG. 5 is a schematic cross-sectional view illustrating the fabrication of a delamination layer on a substrate according to the present embodiment;

FIG. 6 is a schematic cross-sectional view illustrating a light-emitting layer formed on a substrate according to the present embodiment;

FIG. 7 is a schematic cross-sectional view illustrating the removal of the anti-stiction strippable film layer on the substrate according to the present embodiment;

FIG. 8 is a schematic cross-sectional view illustrating the fabrication of an isolation pillar on a substrate according to the present embodiment;

FIG. 9 is a schematic cross-sectional view illustrating a cathode layer formed on a substrate according to the present embodiment;

FIG. 10 is a cross-sectional view illustrating a first inorganic layer formed on a substrate according to the present embodiment;

FIG. 11 is a schematic cross-sectional view illustrating the fabrication of an organic layer on a substrate according to the present embodiment;

fig. 12 is a schematic cross-sectional view illustrating a second inorganic layer formed on a substrate according to the present embodiment.

Description of reference numerals:

10. a substrate;

20. a thin film transistor;

30. a planarization layer;

40. a pixel defining layer;

401. a dam;

402. an aperture on the pixel defining layer;

50. a cathode layer;

60. a first inorganic layer;

70. an organic layer;

80. a second inorganic layer;

90. an anode layer;

100. a tack-reducing peelable film layer;

110. an isolation column;

120. and a light emitting layer.

Detailed Description

To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

Referring to fig. 1 to 12, the present embodiment provides a method for manufacturing a display panel, including the following steps: fabricating the thin film transistor 20 on the substrate 10, see step S1 of fig. 1; the Thin Film Transistor 20 (TFT) is used as a switch to control whether some lines on the display panel are conducted, and the structure is shown in fig. 2. The substrate 10 is a glass substrate or a plastic substrate. The thin film transistor 20 has a top gate structure or a bottom gate structure, and the thin film transistor 20 includes a source electrode, a drain electrode, a gate electrode, and an active layer. For example, in a thin film transistor of a bottom gate structure, a gate electrode is provided at the lowermost portion, and a gate insulating layer is provided on the gate electrode. An active layer is arranged on the gate insulating layer and is arranged right above the gate. A source electrode and a drain electrode are disposed on the active layer. The grid electrode of the thin film transistor with the top grid structure is positioned above the active layer.

When the thin film transistor is manufactured on the substrate, the method also comprises a manufacturing connection circuit, wherein the connection circuit comprises a scanning line and a data line. The scanning lines are used for controlling the on-off of the thin film transistors, and the data lines are used for providing data signals for the thin film transistors. In general, a source of the thin film transistor is connected to a data line, and a gate thereof is connected to a scan line. These connection lines function to connect components inside the display panel.

In order to fill up the unevenness caused by the formation of the thin film transistor on the substrate, a planarization layer 30 is formed; referring to step S1 of fig. 1, in particular, a planarization layer 30 may be formed on the thin film transistor 20 by chemical vapor deposition (cvd) to plate silicon nitride, silicon oxide or other insulating materials, as shown in fig. 2. The planarization layer 30 has certain thickness, the upper surface of planarization layer 30 is comparatively smooth plane, can level and smooth the interior segment difference that causes because of various different layer patterns on the base plate of display device, the good stack of follow-up rete of being convenient for promotes the display effect.

After the planarization layer is manufactured, manufacturing a hole on the planarization layer; referring to step S2 of fig. 1, an etching process may be used to form a hole in the planarization layer, where the bottom of the hole in the planarization layer is a source or a drain of the thin film transistor, as shown in fig. 3. Holes in the planarization layer are used to connect the source (or the drain) to the anode layer, so when anode layer 90 is to connect the source, then holes are etched in planarization layer 30 over the source; when the anode layer 90 is to be connected to the drain, a hole is etched in the planarization layer 30 over the drain.

Manufacturing an anode layer 90, wherein the anode layer 90 is connected with a source electrode or a drain electrode through a hole in the planarization layer; referring to step S1 of fig. 1, specifically, a photoresist is coated and then patterned, that is, the photoresist is exposed and developed, so that the portion of the anode layer to be formed is opened. An anode layer material, such as Indium Tin Oxide (ITO) or the like, is sputtered or evaporated to form an anode layer 90 on the planarization layer, as shown in fig. 3. The anode layer 90 need not cover the entire planarization layer 30. After the anode layer 90 is manufactured, the anode layer is subjected to photoresist stripping and cleaning. Preferably, the anode layer 90 is connected to a drain of the thin film transistor to control electrical properties of the thin film transistor.

Referring to step S2 of fig. 1, a pixel defining layer 40 is fabricated, the pixel defining layer 40 being located over the anode layer 90 and the planarization layer 30. The role of the pixel definition layer 40 is to define each individual sub-pixel element of the display panel, the size of which defines the size of a single display element of the display panel. If holes are formed in the pixel defining layer and the bottom of the holes 402 in the pixel defining layer is the anode layer 90, the pixel defining layer includes the bank 401 and the holes 402 in the pixel defining layer, and the bank 401 is the non-hole region, as shown in fig. 4. The hole in the pixel defining layer may also be made by an etching process. The lower surfaces of the holes 402 on the pixel definition layer are in contact with the upper surface of the anode layer 90, and are in a one-to-one correspondence relationship. When the holes on the pixel definition layer are filled with organic light-emitting functional materials, the organic light-emitting functional materials are in contact with the anode layer of the bottom layer, and the electrical connection is realized.

Due to the printing accuracy of the inkjet printing apparatus itself, the light emitting layer may be printed on the non-porous region (i.e., bank) on the pixel defining layer, and the organic light emitting functional material on the non-porous region of the pixel defining layer may affect the quality of display. Meanwhile, as the display field has higher requirements on the picture quality and higher display resolution, and the pixels (holes on the pixel definition layer) are smaller and smaller, the phenomenon of 'bridging' is more and more serious. To solve this problem, a viscosity-reducing peelable film layer 100 is manufactured, the viscosity-reducing peelable film layer 100 covering a non-porous region (i.e., a bank) on a pixel defining layer; referring to step S3 of fig. 1, specifically, the anti-adhesion peelable film layer 100 is formed on the substrate by inkjet printing or evaporation. Preferably, the anti-adhesion peelable film layer 100 covers the upper surface of the bank 401 of the pixel defining layer, as shown in fig. 5, so that the organic light-emitting functional material that is mistakenly hit on the bank of the pixel defining layer can be removed later, as shown in fig. 6 and 7. The tack-reducing peelable film layer 100 can be a heat tack-reducing adhesive or a UV tack-reducing adhesive. The heating viscose reducing agent is mainly prepared from resin, a curing agent, an organic solvent and the like, and has certain viscosity. The viscosity of the heating viscosity-reducing adhesive is reduced after heating, so that the heating viscosity-reducing adhesive can be peeled off from the pixel defining layer without damaging the pixel defining layer. The UV visbreaking adhesive is mainly prepared from one or more of solvent-type pressure-sensitive adhesives, functional oligomers or multifunctional monomers or a composition thereof, a cross-linking agent, a photoinitiator, a solvent and the like, and also has certain adhesive force. The UV visbreaking adhesive is weakened in viscosity when irradiated by UV light, so that the UV visbreaking adhesive can be peeled off from the pixel defining layer without damaging the pixel defining layer.

After the anti-sticking peelable film layer 100 is manufactured, manufacturing a light-emitting layer 120 in the hole on the pixel defining layer 40 by an ink-jet printing technology; referring to step S4 of fig. 1, the organic light emitting functional material includes, but is not limited to, a hole injection layer, a hole transport layer, an electron blocking layer, an organic light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. The hole injection layer, the hole transport layer, the electron blocking layer, the organic light emitting layer, the hole blocking layer, the electron transport layer and the electron injection layer can be sequentially manufactured by an ink jet printing technology, and the structure is shown in fig. 6 and 7. The light emitting layer 120 is in the hole of the pixel defining layer and connects the anode layer 90 below. Due to the accuracy limitations of the inkjet printing apparatus itself, it inevitably prints to areas outside the holes, i.e. possibly on top of the banks of the pixel definition layer. However, since the anti-adhesion peelable film layer 100 is prepared before this step, the organic light-emitting functional material printed on the anti-adhesion peelable film layer can be peeled off and removed together with the anti-adhesion peelable film layer 100 in a subsequent step, so that the phenomenon that the organic light-emitting functional material bridges at the top of the pixel defining layer can be avoided. The cost for manufacturing the anti-sticking strippable film layer is low, the process steps are not complicated, the display effect and the quality of the display panel can be effectively improved, and the display panel is endowed with greater advantages.

Referring to step S5 of fig. 1, after printing the organic light-emitting functional material in the holes of the pixel defining layer, the viscosity of the anti-adhesion peelable film layer at the dam crest is weakened by heating or UV light, and the anti-adhesion peelable film layer is peeled off, so that the unnecessary organic light-emitting functional material can be taken away, and the structure is shown in fig. 6 and 7.

After the light emitting layer 120 is manufactured, a cathode layer 50 is manufactured; referring to step S7 of fig. 1, specifically, a photoresist is coated, patterned, i.e., exposed and developed, so that the portion where the cathode layer is to be fabricated is opened. Then, a cathode layer material is plated by sputtering or evaporation, and the cathode layer is formed on the light emitting layer 120 and the pixel defining layer 40, and covers the light emitting layer 120, and the structure is shown in fig. 9. The cathode layer 50 is mainly made of a low work function, and can be made of a silver magnesium alloy material mixed in a certain proportion, or lithium fluoride (LiF) or the like. The cathode layer has the main function of providing electrons for the light-emitting functional layer, and adopts a material with low work function as the cathode layer, so that the electron injection efficiency can be improved, the Joule heat generated during the working of the OLED can be reduced, and the service life of the device is prolonged.

In some embodiments, before the cathode layer is fabricated, the isolation pillars 110 may be fabricated in the non-porous region on the pixel definition layer; referring to step S6 of fig. 1, generally, one or more of the pillars 110 may be fabricated and distributed at intervals throughout the light emitting layer 120. The isolation column 110 serves to provide a good support between the substrate and the cover plate, and also to control the thickness and uniformity between the substrate and the cover plate, and the structure is shown in fig. 8. Preferably, the isolation pillar 110 is not connected to the light emitting layer 120, so as to avoid affecting the light emitting effect of the light emitting layer 120. After the isolation pillars 110 are fabricated, the cathode layer directly covers the isolation pillars 110, and the structure diagram is shown in fig. 9.

In some embodiments, the method further includes performing a thin film encapsulation process on the display device having the above components, and forming a first inorganic layer 60 on the cathode layer; referring to step S8 of fig. 1, the first inorganic layer 60 is patterned on the cathode layer by atomic layer deposition or chemical vapor deposition technique, preferably chemical vapor deposition technique. The first inorganic layer 60 covers the cathode layer 50, and the structure is shown in fig. 10. The first inorganic layer 60 may be made of one or more of silicon nitride, silicon oxide, or silicon oxynitride. The first inorganic layer 60 is used to block moisture and oxygen in the environment, and prevent moisture and oxygen from entering the light emitting layer through the cathode layer, and such encapsulation is to improve the lifetime of the display panel. Fabricating an organic layer 70 on the first inorganic layer 60; referring to step S9 of fig. 1, the organic layer 70, which may be Hexamethyldisiloxane (HMDSO), is formed on the first inorganic layer 60 by an inkjet printing technique. The organic layer 70 covers the first inorganic layer 60, and the structure is shown in fig. 11. The organic layer 70 serves to planarize the first inorganic layer 60, covering the problem of pin-hole grain boundaries on the surface of the first inorganic layer 60. Referring to step S10 of fig. 1, a second inorganic layer 80 is formed on the organic layer 70, the material of the second inorganic layer 80 is the same as that of the first inorganic layer 60, and the process for forming the second inorganic layer 80 is the same as that of the first inorganic layer 60. The second inorganic layer 80 covers the organic layer 70, and the structure is shown in fig. 12. The second inorganic layer 80 is used for matching with the first inorganic layer 60 and the organic layer 70, and is used for blocking water vapor and oxygen in the environment through a three-layer thin film packaging structure, so that good water vapor tightness is realized, and the service life of the display panel is further prolonged. Finally, a cover plate may be placed over the second inorganic layer 80.

In the embodiment, the anti-stiction peelable layer can be formed not only on the pixel definition layer of an OLED (organic light-Emitting Diode) display panel, but also on the pixel definition layer of an lcd (liquid Crystal display) display panel.

The embodiment also provides a display panel, and the display panel is manufactured by the manufacturing method of the display panel.

It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.

Claims (9)

1. A manufacturing method of a display panel is characterized by comprising the following steps:

manufacturing a pixel definition layer on a substrate, and manufacturing a hole on the pixel definition layer, wherein the hole on the pixel definition layer is used for accommodating a light emitting layer;

manufacturing a viscosity-reducing strippable film layer, wherein the viscosity-reducing strippable film layer covers a non-hole area on the pixel defining layer;

manufacturing a light emitting layer in the hole on the pixel defining layer by an ink jet printing technology;

and removing the viscosity-reducing strippable film layer.

2. The method for manufacturing a display panel according to claim 1, wherein the step of removing the anti-adhesion peelable film layer comprises:

the viscosity-reducing peelable film layer is heating viscosity-reducing glue, and the heating viscosity-reducing glue is subjected to heating treatment to reduce the viscosity of the heating viscosity-reducing glue;

and stripping the heating and viscosity reducing glue from the pixel defining layer.

3. The method for manufacturing a display panel according to claim 2, wherein the step of removing the anti-adhesion peelable film layer comprises:

the anti-adhesion peelable film layer is UV anti-adhesion glue, and the UV anti-adhesion glue is irradiated by UV light and used for weakening the adhesion of the heating anti-adhesion glue;

the UV subtractive adhesive is peeled from the pixel defining layer.

4. The method for manufacturing a display panel according to claim 1, wherein the specific steps for manufacturing the anti-adhesion peelable film layer are as follows:

the viscosity-reducing strippable film layer is manufactured in an ink-jet printing or evaporation mode.

5. The method of claim 1, further comprising the steps of, before the step of forming the pixel defining layer on the substrate:

manufacturing a thin film transistor on a substrate;

manufacturing a planarization layer, and manufacturing a hole on the planarization layer, wherein the bottom of the hole on the planarization layer is a source electrode or a drain electrode of the thin film transistor;

manufacturing an anode layer, wherein the anode layer is connected with a source electrode or a drain electrode through a hole in the planarization layer;

the pixel definition layer is disposed on the anode layer and the planarization layer, and a bottom of the hole on the pixel definition layer is an anode.

6. The method for manufacturing a display panel according to claim 1, further comprising the following steps after removing the anti-adhesion peelable film layer:

manufacturing an isolation column in a non-hole area on the pixel definition layer;

and manufacturing a cathode layer.

7. The method for manufacturing a display panel according to claim 6, further comprising the steps of:

manufacturing a first inorganic layer on the cathode layer;

manufacturing an organic layer;

a second inorganic layer is fabricated.

8. The method of claim 5, further comprising, when forming the thin film transistor on the substrate:

and manufacturing a scanning line and a data line, wherein the scanning line is connected with the grid electrode of the thin film transistor, and the data line is connected with the source electrode of the thin film transistor.

9. A display panel manufactured by the method of any one of claims 1 to 8.

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