WO2023035415A1

WO2023035415A1 - Oled packaging method and oled package structure

Info

Publication number: WO2023035415A1
Application number: PCT/CN2021/132556
Authority: WO
Inventors: 何文双; 吴炜钦; 罗武峰; 蔡晓义
Original assignee: 信利（惠州）智能显示有限公司
Priority date: 2021-09-07
Filing date: 2021-11-23
Publication date: 2023-03-16
Also published as: CN114094033A

Abstract

The present invention relates to an OLED packaging method, comprising the following steps: step S1, providing a substrate, and forming a display function layer on the substrate; step S2, forming, on the substrate, a first barrier layer surrounding the display function layer, and patterning the first barrier layer to form a plurality of flow channels located on the first barrier layer; step S3, forming, on the substrate, a second barrier layer surrounding the first barrier layer; step S4, forming, on the substrate, a third barrier layer surrounding the second barrier layer; step S5, forming a first inorganic package layer on the substrate; step S6, forming an organic package layer on the first inorganic package layer; and step S7, forming a second inorganic package layer on the organic package layer. The present invention also relates to an OLED package structure.

Description

OLED encapsulation method and OLED encapsulation structure

technical field

The invention relates to the field of display technology, in particular to an OLED packaging method and an OLED packaging structure.

Background technique

Organic Light-Emitting Diode (OLED) has the characteristics of self-illumination, high brightness, wide viewing angle, high contrast, flexibility, and low energy consumption. Therefore, OLED display technology is widely used in mobile phone screens, computer monitors, Color TV etc. OLEDs generally include: a substrate, an anode on the substrate, a hole injection layer on the anode, a hole transport layer on the hole injection layer, a light-emitting layer on the hole transport layer, and a light-emitting layer on the light-emitting layer. An electron transport layer on the electron transport layer, an electron injection layer on the electron transport layer, and a cathode on the electron injection layer. The light-emitting principle of OLED devices is that semiconductor materials and organic light-emitting materials are driven by an electric field to cause light emission through carrier injection and recombination. Specifically, OLED devices usually use indium tin oxide (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. Layer, electrons and holes migrate to the light-emitting layer through the electron-transport layer and hole-transport layer respectively, and meet in the light-emitting layer to form excitons and excite light-emitting molecules, which emit visible light through radiation relaxation. OLED can realize flexible display by using a bendable plastic substrate as a carrier, and then cooperate with a thin film packaging process to realize a bendable flexible OLED display.

Organic light-emitting devices of OLEDs are susceptible to degradation caused by intrinsic factors (e.g., degradation of electrodes and light-emitting layers caused by oxygen, degradation caused by reactions between light-emitting layers and interfaces) and deterioration caused by external factors (e.g., external Moisture, oxygen, UV rays and manufacturing conditions). Therefore, encapsulation is a crucial link in the OLED manufacturing process, and the quality of the encapsulation directly affects its airtightness, which in turn leads to major changes in the service life and quality of the product.

The encapsulation layer prepared in the existing OLED encapsulation process includes an inorganic layer and an organic layer. The encapsulation effect is achieved by stacking several layers. Generally, the inorganic layer is prepared by vacuum deposition, and the organic layer is prepared by inkjet printing. Because there will be gaps between inkjet printing nozzles, the organic layer after inkjet printing is generally flattened into the device by static leveling to form a covering package.

The technical problem existing in the existing encapsulation process is that it is difficult to ensure the uniformity and linearity of the film thickness of the organic layer, which affects the uniformity and linearity of the film thickness of the encapsulation layer, which has a great impact on the OLED encapsulation quality and display effect.

Definition of Terms

The "display function layer" described in the present invention includes an anode layer provided on a substrate (the anode layer includes an anode provided on the substrate, a hole injection layer provided on the anode, and a hole injection layer provided on the hole injection layer. Transport layer), light-emitting layer (light-emitting layer is arranged on the hole transport layer), cathode layer (the cathode layer includes the electron-transport layer arranged on the light-emitting layer, the electron-injection layer arranged on the electron-transport layer and the electron-injection layer arranged on the on the cathode).

The "display area" described in the present invention refers to the area covered by the projection of the display function layer along the direction perpendicular to the substrate.

Contents of the invention

Aiming at the technical problems in the prior art, the present invention provides an OLED encapsulation method, which is more conducive to the leveling of organic layer materials, thereby improving the film thickness uniformity of the encapsulation layer.

In one aspect, the present invention provides an OLED packaging method. Including the following steps:

Step S1, providing a substrate, and forming a display function layer on the substrate;

Step S2, forming a first barrier layer surrounding the display function layer on the substrate, and patterning the first barrier layer to form a plurality of flow channels on the first barrier layer;

Step S3, forming a second barrier layer surrounding the first barrier layer on the substrate;

Step S4, forming a third barrier layer surrounding the second barrier layer on the substrate;

Step S5, forming a first inorganic encapsulation layer on the substrate;

Step S6, forming an organic encapsulation layer on the first inorganic encapsulation layer;

Step S7, forming a second inorganic encapsulation layer on the organic encapsulation layer.

Wherein, the first inorganic encapsulation layer, the organic encapsulation layer and the second inorganic encapsulation layer stacked sequentially from bottom to top constitute the encapsulation layer.

Wherein, the height value of the second barrier layer is not less than the height value of the first barrier layer, the height value of the third barrier layer is greater than the height value of the second barrier layer, and the sum of the height values of the encapsulation layer and the display function layer is greater than the third barrier layer The height value of the layer. Therefore, the third barrier layer is prevented from increasing the thickness of the OLED after encapsulation.

In the present invention, printing techniques can be used to manufacture (eg, deposit or pattern) the organic encapsulation layer. For example, the organic encapsulant material can be dissolved or otherwise suspended in a carrier fluid (e.g., a solvent), and the organic encapsulant layer comprising the organic encapsulant material can be printed by inkjet printing followed by evaporation of the carrier fluid to provide a patterned layer. form. For example, the organic encapsulation layer material can be inkjet printed onto the substrate in a certain pattern as a liquid mixture of organic compounds, the patterned organic layer coats at least a portion of the display area fabricated on the substrate and is then passed through a curing process (e.g., Cured by UV illumination) to cause a cross-linking reaction, thereby forming a patterned solid layer. In another approach, the solid-phase organic encapsulation layer material can be thermally vaporized for deposition onto the substrate via spraying. In yet another method, the organic encapsulation material can be dissolved or otherwise suspended in a carrier fluid, and the organic encapsulation layer comprising the organic encapsulation material can be formed by dispensing a continuous fluid stream from a nozzle to the substrate above to form lines and then evaporate the carrier fluid to provide a line patterned layer. Such methods can generally be referred to as organic "printing" techniques and can be implemented using printing systems.

The present inventors have realized that the key to improving the uniformity of the film thickness of the packaging layer in the display area is to improve the uniformity of the film thickness of the organic packaging layer in the display area. The organic packaging layer material is dissolved or otherwise suspended in the carrier fluid, Then, the carrier fluid is applied to the substrate through organic "printing" technology. At this time, the carrier fluid completely covers the display area, and the carrier fluid can perform flow or dispersion operations to improve the planarization or uniformity of the organic packaging layer. The duration of the flow or dispersion operation can usually be longer than the duration of the solidification of the organic encapsulation layer material. Therefore, before the organic encapsulation layer material is solidified to form an organic encapsulation layer, in order to ensure the uniformity and linearity of the organic encapsulation layer film thickness, it is necessary to suppress the carrier fluid. Spill and flow velocity into the non-display area.

The inventors have unexpectedly discovered that the combination of the first barrier layer, the second barrier layer, and the third barrier layer can improve the uniformity of the encapsulation layer in the display area by reducing or minimizing unevenness or other visible defects. The setting of the first barrier layer through the flow channel can increase the contact area with the carrier fluid during the flow or dispersion operation, thereby inhibiting the flow velocity of the carrier fluid to the non-display area, and the setting of the second barrier layer and the third barrier layer can Spillage of the carrier fluid to the area of the non-display area is inhibited by physical contact with the carrier fluid.

In another aspect, the present invention provides an OLED packaging structure, comprising:

Substrate;

a display function layer arranged on the substrate;

Surrounding the first barrier layer of the display function layer, a plurality of flow channels are arranged on the first barrier layer;

a second barrier layer surrounding the first barrier layer, the gap between the first barrier layer and the second barrier layer being a first buffer zone;

a third barrier layer surrounding the second barrier layer, and the gap between the second barrier layer and the third barrier layer is a second buffer zone;

The encapsulation layer arranged on the display function layer, the encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked sequentially from bottom to top, wherein both the first inorganic encapsulation layer and the second inorganic encapsulation layer cover the display The functional layer, the first barrier layer, the first buffer zone, the second barrier layer, the second buffer zone, and the third barrier layer, and the organic encapsulation layer covers the display function layer, the first barrier layer, and the first buffer zone.

Wherein, both the second barrier layer and the third barrier layer are closed surrounding structures, the height value of the second barrier layer is not less than the height value of the first barrier layer, and the height value of the third barrier layer is greater than the height value of the second barrier layer , the sum of the heights of the encapsulation layer and the display function layer is greater than the height of the third barrier layer.

Preferably, the vertical cross-sections of the second barrier layer and the third barrier layer are both trapezoidal structures.

Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

1. The first barrier can improve the uniformity and linearity of the organic encapsulation layer prepared in the OLED encapsulation process, thereby improving the encapsulation effect and improving product quality and yield;

2. In the preparation process of the organic encapsulation layer, after the carrier fluid is organically "printed" on the substrate, the carrier fluid coats more areas, or when the linearity is not good during the flow or dispersion operation, the second barrier layer and the third barrier layer can prevent the carrier fluid from overflowing to the outside of the third barrier layer so that the carrier fluid cannot completely cover the display area and thus the package fails.

The following will be described in conjunction with specific embodiments.

Description of drawings

The accompanying drawings further illustrate the present invention, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention.

FIG. 1 is a schematic diagram of an OLED packaging structure provided by an embodiment of the present invention;

2 is a top view of the OLED packaging structure provided by an embodiment of the present invention after removing the packaging layer;

FIG. 3 is an enlarged view of part A in FIG. 2 .

Wherein, reference signs are: 1. substrate; 2. display function layer; 31. first barrier layer; 311. rectangular block; 312. flow channel; 32. second barrier layer; 33. third barrier layer; 41. The first inorganic encapsulation layer; 42. The second inorganic encapsulation layer; 5. The organic encapsulation layer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

For reference and clarity, descriptions, abbreviations or abbreviations of technical terms used in the following text are summarized as follows:

OLED: Organic Light-Emitting Diode organic light-emitting diode;

TFE: Thin Film encapsulation;

PECVD: Plasma Enhanced Chemical Vapor Deposition Plasma Enhanced Chemical Vapor Deposition;

UV: Ultravioletray ultraviolet light.

As shown in Figure 1-2, this embodiment provides an OLED packaging structure, including:

Substrate 1;

a display function layer 2 disposed on the substrate 1;

Surrounding the first barrier layer 31 of the display function layer, the first barrier layer 31 is provided with a plurality of flow channels 312;

The second barrier layer 32 surrounding the first barrier layer 31, the gap between the first barrier layer 31 and the second barrier layer 32 is a first buffer zone;

A third barrier layer 33 surrounding the second barrier layer 32, the gap between the second barrier layer 32 and the third barrier layer 33 is a second buffer zone;

The encapsulation layer arranged on the display function layer 2, the encapsulation layer includes a first inorganic encapsulation layer 41, an organic encapsulation layer 5, and a second inorganic encapsulation layer 42 stacked sequentially from bottom to top, wherein the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer The encapsulation layer 42 all covers the display function layer 2, the first barrier layer 31, the first buffer zone, the second barrier layer 32, the second buffer zone, and the third barrier layer 33, and the organic encapsulation layer 5 covers the display function layer 2, the first barrier layer Barrier layer 31, the first buffer zone.

In this embodiment, the height value of the first barrier layer 31 is smaller than the height value of the second barrier layer 32, the height value of the second barrier layer 32 is smaller than the height value of the third barrier layer 33, the height of the packaging layer and the display function layer 2 The sum of the values is greater than the height value of the third barrier layer 31 .

As shown in Figure 3, in this embodiment, the first barrier layer 31 includes several independent rectangular blocks 311, the rectangular blocks 311 are arranged in two rows, there are gaps between adjacent barrier blocks 311, and the adjacent gaps form a Straight flow channel 312 .

The encapsulation layer in this embodiment can be prepared by using the TFE process in the prior art.

This embodiment also provides an OLED packaging method. Including the following steps:

Step S1, providing a substrate 1 on which a display function layer 2 is formed;

Step S2, forming a first barrier layer 31 surrounding the display function layer 2 on the substrate 1, and patterning the first barrier layer 31 to form a plurality of flow channels on the first barrier layer 31;

Step S3, forming a second barrier layer 32 surrounding the first barrier layer 31 on the substrate 1;

Step S4, forming a third barrier layer 33 surrounding the second barrier layer 32 on the substrate 1;

Step S5, forming a first inorganic encapsulation layer 41 on the substrate 1;

Step S6, forming an organic encapsulation layer 5 on the first inorganic encapsulation layer 41;

Step S7 , forming a second inorganic encapsulation layer 42 on the organic encapsulation layer 5 .

In this embodiment, the substrate 1 is a flexible plastic substrate. In step S1, the existing technical solution can be used to prepare the display function layer 2 on the plastic substrate. The specific structure of the display function layer 2 is: from bottom to top, it includes anode , an organic luminescent material layer, and a cathode.

In this embodiment, the specific process of forming the first barrier layer 31, the second barrier layer 32, and the third barrier layer 33 is as follows:

Step 1, coating the black polystyrene material on the substrate 1 using the prior art;

Step 2, using the first half-tone mask to form the first barrier layer 31 through the exposure process, the first half-tone mask is provided with a first light-transmitting area, and the first light-transmitting area is provided with a pattern. Under the irradiation of UV light, the ultraviolet light passes through the first light-transmitting area and irradiates the area on the substrate 1 where the first barrier layer 31 is formed, and the coated black polystyrene material located in this area is cured to form a corresponding pattern (that is, a plurality of independent Rectangular block 311), the uncured polystyrene material in this region exposes the substrate 1 and forms the flow channel 312 after subsequent removal;

Step 3, using a second half-tone mask to form a second barrier layer 32 through an exposure process, and the second half-tone mask is provided with a second light-transmitting region;

Step 4, using a third half-tone mask to form a third barrier layer 33 through an exposure process, and a third light-transmitting region is provided on the third half-tone mask;

Step five, removing the uncured polystyrene material on the substrate 1 .

Among them, the third light transmission area and the light transmission are sufficient, and the first light transmission area and the second light transmission area are relatively low in light transmission. If the light transmittance is higher, the black polystyrene material coated in the corresponding area is cured more completely. Therefore, the height difference between the first barrier layer 31 , the second barrier layer 32 and the third barrier layer 33 is formed by controlling the light transmittance of the first light transmission area, the second light transmission area, and the third light transmission area.

In order to miniaturize the packaged OLED, the gap between the first barrier layer 31 and the display function layer 2 should be as small as possible without affecting the display effect.

In this embodiment, the encapsulation layer includes a first inorganic encapsulation layer 41, an organic encapsulation layer 5, and a second inorganic encapsulation layer 42 stacked sequentially from bottom to top. Encapsulation layer 42 wraps. Wherein, the organic encapsulation layer material for preparing the organic encapsulation layer 5 can generally be organic materials such as methyl methacrylate, epoxy resin, polycarbonate, polystyrene, phenolic resin, etc., and the refractive index is usually between 0.4-1.3; The composition of the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer 42 can generally be inorganic materials such as silicon nitride, silicon oxide, silicon oxycarbide, aluminum oxide, etc., and the refractive index is between 1.9-2.5. When the light generated by the display function layer 2 is emitted from the first inorganic encapsulation layer 41 (optical dense medium) to the interface with the organic encapsulation layer 5 (optical thinning medium), the incident angle of the light in the first inorganic encapsulation layer 41 As the angle of refraction in the organic encapsulation layer 5 increases continuously, it increases to 90° prior to the incident angle. At this time, if the incident angle is further increased, all the light is reflected back to the first inorganic encapsulation layer 41, resulting in Total reflection reduces the luminous brightness and efficiency of OLED. Therefore, if the number of organic and inorganic encapsulation layers of the encapsulation layer is increased, although the encapsulation effect will be indicated, the number of total reflections will increase and the light output rate will be lower. The OLED light output rate directly affects the display effect. Therefore, considering the OLED light output rate and Encapsulation effect, the encapsulation layer is arranged as the structure of the first inorganic encapsulation layer 41 , the organic encapsulation layer 5 , and the second inorganic encapsulation layer 42 stacked sequentially from bottom to top, which can significantly improve the ability to block water and oxygen.

In this embodiment, the material for preparing the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer 42 is preferably SiN _x . The process for preparing the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer 42 is preferably a PECVD deposition process. Preferably, the film thicknesses of the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer 42 are both 200-800 nm, and the refractive indices of the first inorganic encapsulation layer 41 and the second inorganic encapsulation layer 42 are between 1.9-2.5 .

In this embodiment, methyl methacrylate (MMA) is used to prepare the organic encapsulation layer 5; MMA is dissolved in organic solvents such as toluene, and a photoinitiator is added to form a suspension with good uniformity; then inkjet printing The suspension is coated on the first inorganic encapsulation layer 41 in the same way, and the organic encapsulation layer 5 is formed after drying and UV light curing. Preferably, the thickness of the organic encapsulation layer 5 is 2-10um. After the suspension is coated on the first inorganic encapsulation layer 41 by means of inkjet printing, the suspension covers the display area and is concentrated in the first barrier layer 31, and then the suspension performs a flow or dispersion operation, at this time The suspension will flow to the first buffer zone through the channel 312 of the first barrier layer 31. Due to the bent structure of the channel 312 and the distribution structure of the multi-channel 312, the flow velocity of the suspension through the first barrier layer 31 is significantly It reduces and is more conducive to leveling, and improves the film thickness uniformity of the organic encapsulation layer 5 in the display area, thereby improving the light emitting uniformity of the OLED. The width of the channel 312 is the width of the gap between adjacent rectangular blocks 311 , and the depth of the channel 312 is the thickness of the first barrier layer 31 minus the thickness of the first inorganic encapsulation layer 41 . The flow velocity of the suspension can be further reduced by controlling the width and depth of the flow channel 312 .

The first buffer zone is used to accommodate part of the suspension that overflows from the first barrier layer 31, and the overflow of the suspension is suppressed by setting the second barrier layer 32, and the second buffer zone is used to accommodate a small amount of overflow from the second barrier layer 32 The third barrier layer 33 prevents the suspension from overflowing to the outside of the third barrier layer 33 so that the suspension cannot completely cover the display area. The suspension is also cured by UV light during the flow or dispersion operation, so the suspension will gradually solidify into the organic encapsulation layer 5 during the flow or dispersion operation. The width of the second buffer is smaller than the width of the first buffer. Preferably, the width of the second buffer zone is 1/3 of the width of the first buffer zone, which can take into account both the miniaturization of the OLED and the accommodation effect for the suspension.

In the OLED packaging method of the present invention, a plurality of flow channels 312 are obtained by patterning the first barrier layer formed on the OLED device, and a second barrier layer and a third barrier layer are arranged on the periphery of the first barrier layer, so that the organic packaging The flow or dispersion operation of the layer material is suppressed, which is more conducive to leveling and improves the uniformity of the film thickness of the organic packaging layer 5, thereby improving the uniformity and linearity of the film thickness of the packaging layer.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims

A kind of OLED encapsulation method, is characterized in that, comprises the steps:

Step S1, providing a substrate, and forming a display function layer on the substrate;

Step S2, forming a first barrier layer surrounding the display function layer on the substrate, and patterning the first barrier layer to form a plurality of flow channels on the first barrier layer;

Step S3, forming a second barrier layer surrounding the first barrier layer on the substrate;

Step S4, forming a third barrier layer surrounding the second barrier layer on the substrate;

Step S5, forming a first inorganic encapsulation layer on the substrate;

Step S6, forming an organic encapsulation layer on the first inorganic encapsulation layer;

Step S7, forming a second inorganic encapsulation layer on the organic encapsulation layer.
The OLED encapsulation method according to claim 1, wherein the material for preparing the first inorganic encapsulation layer and the second inorganic encapsulation layer is SiN x .
The OLED encapsulation method according to claim 2, characterized in that the first inorganic encapsulation layer and the second inorganic encapsulation layer are prepared by using a PECVD deposition process.
The OLED encapsulation method according to claim 2, characterized in that the material for preparing the organic encapsulation layer is methyl methacrylate.
The OLED encapsulation method according to claim 4, characterized in that, the methyl methacrylate is dissolved in toluene, and a photoinitiator is added to make a suspension, and then inkjet printing is used on the first inorganic The suspension is coated on the encapsulation layer, and the organic encapsulation layer is formed through drying and UV light curing.
The OLED packaging method according to claim 1, wherein the substrate is a bendable plastic substrate.
An OLED encapsulation structure, characterized in that it comprises:

Substrate;

a display function layer disposed on the substrate;

Surrounding the first barrier layer of the display function layer, the first barrier layer is provided with a plurality of flow channels;

a second barrier layer surrounding the first barrier layer, the gap between the first barrier layer and the second barrier layer being a first buffer zone;

a third barrier layer surrounding the second barrier layer, and the gap between the second barrier layer and the third barrier layer is a second buffer zone;

The encapsulation layer arranged on the display function layer, the encapsulation layer includes a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked in sequence from bottom to top, the first inorganic encapsulation layer and the second inorganic encapsulation layer Both inorganic encapsulation layers cover the display function layer, the first barrier layer, the first buffer zone, the second barrier layer, the second buffer zone, the third barrier layer, the organic The encapsulation layer covers the display function layer, the first barrier layer, and the first buffer zone.
The OLED encapsulation structure according to claim 7, wherein the second barrier layer and the third barrier layer are closed surrounding structures.
The OLED packaging structure according to claim 7, characterized in that: the first barrier layer comprises several independent rectangular blocks, the rectangular blocks are arranged in two rows, and there are gaps between adjacent barrier blocks, The adjacent gaps form the non-linear flow channel.
The OLED encapsulation structure according to claim 7, wherein the height of the second barrier layer is not less than the height of the first barrier layer, and the height of the third barrier layer is greater than that of the second barrier layer. The height value of the layer, the sum of the height values of the encapsulation layer and the display function layer is greater than the height value of the third barrier layer.