WO2020029365A1

WO2020029365A1 - Preparation method for display device, and organic light-emitting display device

Info

Publication number: WO2020029365A1
Application number: PCT/CN2018/105150
Authority: WO
Inventors: 张育楠; 史婷; 艾娜
Original assignee: 深圳市华星光电半导体显示技术有限公司
Priority date: 2018-08-10
Filing date: 2018-09-12
Publication date: 2020-02-13
Also published as: CN109166966A

Abstract

Disclosed are a preparation method for a display device, and an organic light-emitting display device. The preparation method comprises: providing a substrate; forming an anode metal layer on a surface of the substrate; performing ink-jet printing on the surface, which is away from the substrate, of the anode metal layer to sequentially form a hole injection layer, a hole transport layer and a light-emitting layer which are laminated; performing vacuum baking processing on the substrate after ink-jet printing; and sequentially forming an electron transport layer and a cathode metal layer on the surface, which is away from the hole transport layer, of the light-emitting layer of the substrate after vacuum baking.

Description

Method for preparing display device and organic light emitting display device

Technical field

The present application relates to the technical field of display manufacturing, and in particular, to a method for manufacturing a display device and an organic light emitting display device.

Background technique

In the existing organic light emitting display (Organic Light Emitting Display, OLED), an inkjet printing process is usually used to form a hole injection layer, a hole transport layer, and a light emitting layer. In the process of inkjet printing, in order to improve the coffee ring effect and improve the stability of the ink, a high boiling point solvent is generally added to the ink. On the other hand, in order to improve the compatibility of the ink and the printer, it is also added to the ink. Auxiliary components such as viscosity additives and surface tension additives. However, in the subsequent process, if the residual high-boiling solvents or additives in the organic thin film cannot be effectively removed, the lifetime of the OLED device will be greatly affected.

technical problem

The technical problem mainly solved in this application is how to remove the high boiling point solvents or additives in the OLED device and extend the life of the OLED device.

Technical solutions

In a first aspect, the present application provides a method for manufacturing a display device, including: providing a substrate; forming an anode metal layer on a surface of the substrate; and forming the hole injection layer on a surface of the anode metal layer remote from the substrate. And curing the hole injection layer by vacuum drying and baking; forming the hole transport layer on a surface of the hole injection layer away from the anode metal layer, and curing the cavity by vacuum drying and baking Hole transport layer; forming the light emitting layer on the surface of the hole transport layer away from the hole injection layer, and curing the light emitting layer by vacuum drying and baking; The substrate of the injection layer, the hole transport layer, and the light emitting layer is baked, and the temperature of the baking is lower than that of the substrate when any one of the hole injection layer, the hole transport layer, and the light emitting layer is formed. Temperature; and an electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking.

In a method for manufacturing a display device provided in the present application, a pressure in the vacuum baking device is less than 7 × 10 ^-4 Pa.

In a method for manufacturing a display device provided in the present application, a baking temperature of the vacuum baking device does not exceed 180 degrees Celsius.

In a method for manufacturing a display device provided in this application, the step of forming an anode metal layer on a surface of the substrate includes:

A magnetron sputtering process is used to sputter an indium tin oxide film layer on the surface of the substrate to form the anode metal layer.

In a method for manufacturing a display device provided in the present application, an electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking. Steps, including:

On the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, the electron transport layer and the cathode metal layer are sequentially formed by a vacuum evaporation process.

In a method for manufacturing a display device provided in the present application, an electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking. After the steps, it also includes:

A protective layer and an encapsulating layer are sequentially formed on a surface of the cathode metal layer remote from the electron transport layer.

In a method for manufacturing a display device provided in the present application, the cathode metal layer is made of a metal with a low work function or the composite metal with a low work function.

In a method for manufacturing a display device provided in the present application, the anode metal layer is made of a material with a high work function and a high light transmittance.

In a second aspect, the present application provides a method for manufacturing a display device, including: providing a substrate; forming an anode metal layer on a surface of the substrate; and forming a stacked hole injection layer and an air hole in order by inkjet printing on the surface of the anode metal layer away from the substrate A hole transport layer and a light emitting layer; vacuum baking the substrate after the inkjet printing; forming an electron transport layer and a cathode metal layer on the surface of the light emitting layer of the substrate after the vacuum baking away from the hole transport layer in order.

In a method for manufacturing a display device provided in the present application, the step of vacuum-baking the substrate after inkjet printing includes:

Placing the substrate after inkjet printing in a vacuum baking device for 30 to 180 minutes, and the pressure in the vacuum baking device is less than 7 × 10 ^-4 Pa; and

The baking temperature of the vacuum baking device is lower than the baking temperature when forming any one of the hole injection layer, the hole transport layer, and the light emitting layer, and the baking temperature of the vacuum baking device No more than 180 degrees Celsius.

In a method for manufacturing a display device provided in the present application, the step of sequentially forming a stacked hole injection layer, a hole transport layer, and a light emitting layer by inkjet printing on a surface of the anode metal layer remote from the substrate. include:

Forming the hole injection layer on the surface of the anode metal layer away from the substrate by inkjet printing, and curing the hole injection layer by vacuum drying and baking;

Forming the hole transport layer by inkjet printing on a surface of the hole injection layer remote from the anode metal layer, and curing the hole transport layer by vacuum drying and baking; and

The light emitting layer is formed by inkjet printing on a surface of the hole transporting layer remote from the hole injection layer, and the light emitting layer is cured by vacuum drying and baking.

In a method for manufacturing a display device provided in the present application, an electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking. The steps include:

According to a third aspect, the present application provides an organic light emitting display device. The organic light emitting display device is prepared by the method for manufacturing a display device as described above, and includes: a substrate;

An anode metal layer formed on the substrate;

The hole injection layer is formed on the surface of the substrate by means of inkjet printing, and the hole injection layer is far from the anode metal layer;

A hole transport layer is formed on the hole injection layer by inkjet printing, and the hole transport layer is far from the anode metal layer;

The light-emitting layer is formed on the hole-transporting layer by inkjet printing;

An electron transport layer formed on the light emitting layer after the substrate is vacuum baked, the electron transport layer being far from the hole transport layer; and

A cathode metal layer is formed on the electron transport layer, and the cathode metal layer is far from the hole transport layer.

An organic light emitting display device provided in the present application further includes:

A protective layer formed on a surface of the cathode metal layer remote from the electron transport layer; and

An encapsulation layer is formed on the protection layer.

Beneficial effect

The beneficial effects of the present application are: different from the prior art, in some embodiments of the present application, an anode metal layer is formed on the surface of the substrate; and a stacked hole injection layer is sequentially formed on the surface of the anode metal layer away from the substrate by inkjet printing. , Hole transport layer and light emitting layer; vacuum baking the substrate after inkjet printing; forming an electron transport layer and a cathode metal layer in sequence on the surface of the light emitting layer of the substrate after vacuum baking away from the hole transport layer After the layers requiring inkjet printing are formed, the vacuum baking process can be used to remove the high boiling point solvents or additives remaining in the film layer formed by inkjet printing, thereby reducing the degradation factors of the life of the display device and extending the display device life.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic flowchart of a method for manufacturing a display device according to an embodiment of the present application;

FIG. 2 is a detailed flowchart of each step of the method for manufacturing the display device shown in FIG. 1; FIG.

3 is a schematic diagram of a process for preparing a display device by using the method for manufacturing a display device shown in FIG. 1;

FIG. 4 is a schematic diagram of the process of using the inkjet printing of the HIL layer, the HTL layer, and the EML layer in FIG. 3; FIG.

5 is a schematic structural diagram of an organic light emitting display device according to an embodiment of the present application;

FIG. 6 is another schematic structural diagram of an organic light emitting display according to an embodiment of the present application.

Embodiments of the invention

In the following, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

As shown in FIG. 1, FIG. 1 is a schematic flowchart of a method for manufacturing a display device according to an embodiment of the present application. The method includes:

11: Provide a substrate.

The substrate is a base substrate, which may be a glass substrate or a flexible substrate, such as a flexible printed circuit (FPC), or a structure in which a flexible substrate is provided on the surface of a glass substrate. The type selection is not limited here.

12: An anode metal layer is formed on the substrate surface.

Among them, the anode metal layer needs to use a high work function and a high light transmittance material, such as indium tin oxide (ITO), to form a high work function, stable and transparent ITO transparent conductive film layer.

In some embodiments, please refer to FIG. 2. FIG. 2 is a schematic diagram illustrating specific steps of the method for manufacturing the display device shown in FIG. 1. Step 12 may include:

A magnetron sputtering process can be used to magnetron sputter a layer of indium tin oxide film on the surface of the glass substrate to form an anode metal layer.

Of course, in other embodiments, other processes or other materials may be used to form the anode metal layer, which is not specifically limited herein.

13: Inkjet printing is performed on the surface of the anode metal layer away from the substrate to form a stacked hole injection layer, a hole transport layer, and a light emitting layer in this order.

The hole injection layer can effectively improve the injection of hole carriers, which can improve the performance of the display device. The material of the hole injection layer can be selected according to the type of the display device. For example, the metal oxide is molybdenum trioxide or metal oxide. Combinations of substances and other substances are not specifically limited here.

Since the light-emitting layer material has an electron-transporting shape, a hole-transporting layer is required to adjust the rate of injection of holes and electrons into the light-emitting layer. The hole-transporting layer can also play a role of blocking electrons, so that the injected electrons and holes are at the light-emitting layer Compounding occurs.

Please refer to FIG. 2 and FIG. 4. In the process of forming a hole injection layer (HIL), a hole transport layer (HTL), and a light emitting layer (EML) using an inkjet printing process , Can be carried out in three steps: inkjet printing, vacuum drying and baking. Step 13 includes:

131: Ink-jet printing is performed on the surface of the anode metal layer away from the substrate to form a hole injection layer, and the hole injection layer is cured by vacuum drying and baking.

132: Ink-jet printing is performed on the surface of the hole injection layer away from the anode metal layer to form a hole transport layer, and the hole transport layer is cured by vacuum drying and baking.

133: Ink-jet printing is performed on the surface of the hole-transport layer away from the hole-injection layer to form a light-emitting layer, and the light-emitting layer is cured by vacuum drying and baking.

In the process of inkjet printing, in order to improve the coffee ring effect and improve the stability of the ink, a high boiling point solvent is generally added to the ink. On the other hand, in order to improve the compatibility between the ink and the printer, auxiliary components such as viscosity additives and surface tension additives are also added to the ink. However, if the high boiling point solvents and / or additives are not removed, the life of the display device will be caused. shorten. Because the materials of the HIL layer and the HTL layer have better heat resistance, and the temperature of the hot baking used in the preparation process is relatively high, there are few residual solvents and / or additives. However, the material of the EML layer is relatively inferior in heat resistance, and the hot baking temperature that can be used is not high, so there are many residual solvents and / or additives in the EML layer. In addition, because the HIL layer and the HTL layer are not only used to remove residual solvents during the hot baking process, but also need to undergo other chemical reactions during the heating process of the HIL layer and the HTL layer, in order to meet the needs of display device preparation, which shows that The device may be an OLED device. This chemical reaction cannot proceed in a vacuum environment. Therefore, in this embodiment, in order to remove residual solvents and / or additives in the film layer formed by inkjet printing, especially to remove residual solvents and / or additives in the EML layer, a vacuum baking process is performed after the EML layer is completed in inkjet printing. The hole injection layer, the hole transport layer, and the light-emitting layer are vacuum-dried and baked in a vacuum baking device 16.

14: Vacuum baking the substrate after inkjet printing.

Because the solvent's intermolecular binding force in the vacuum is reduced and the molecular gap is increased, the substrate after the inkjet printing is vacuum-baked, which can make it easier for the residual solvent and / or additives in the film to evaporate out of the film. Layer, thereby reducing the degradation factors of the life of the display device and extending the life of the display device.

In some embodiments, please refer to FIG. 2 and FIG. 3. Step 14 specifically includes:

141: Put the substrate after the inkjet printing into the vacuum baking device 16 and bake for 30 to 180 minutes.

The vacuum baking device 16 may be a vacuum baking furnace or the like. The environment in the vacuum baking device 16 is approximately vacuum, and its pressure may be less than 7 × 10 ^-4 Pa. Meanwhile, in order not to damage the structure of the formed film layer, the baking temperature of the vacuum baking device 16 should be lower than the baking temperature when forming any one of the HIL layer, the HTL layer and the EML layer. In this embodiment, the baking temperature may be set to not more than 180 degrees Celsius, such as 120 degrees Celsius.

15: An electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking.

Among them, the cathode metal layer usually uses metals such as silver (Ag), aluminum (Al), calcium (Ca), indium (In), lithium (Li), and magnesium (Mg), or composite metals with low work function. Made of, for example, magnesium-silver (such as Mg-Ag).

In some embodiments, please refer to FIG. 2 and FIG. 3. Step 15 includes:

151: On the surface of the light-emitting layer of the substrate that is far from the hole transport layer after the vacuum baking, a vacuum evaporation process is used to sequentially form an electron transport layer and a cathode metal layer.

After vacuum baking, the residual solvent and / or additives in the film layer formed by inkjet printing on the surface of the substrate are greatly reduced. At this time, other processes such as vacuum evaporation process can be used to form other organic film layers, as shown in Figure 2 Electron Transport Layer (ETL) and Al layer.

After the above steps 11 to 15, the main functional layer of the display device has been prepared, but in order to improve the service life and effect of the display device and prevent water vapor and other devices from eroding the device, a protective layer may be continuously prepared on the surface of the cathode metal layer.

Specifically, as shown in FIG. 2, in some embodiments, after step 15, the method further includes:

161: A protective layer and an encapsulating layer are sequentially formed on the surface of the cathode metal layer away from the electron transport layer.

The protective layer and the encapsulation layer may be made of an inorganic material that blocks water vapor. In order to improve the flexibility of the display device and facilitate bending, a structure in which inorganic and organic materials are laminated may also be used. It can be set according to actual needs, and is not specifically limited here.

In this embodiment, after all the film layers that require inkjet printing are formed, and before other film layers are formed by vacuum evaporation, the substrate subjected to inkjet printing is subjected to vacuum baking. The high boiling point solvents or additives remaining in the film layer formed by inkjet printing can be removed, thereby reducing the degradation factors of the life of the display device and extending the life of the display device.

Ink-jet printing (IJP) red light devices are taken as an example. In this application, two types of inkjet printing red light devices with and without vacuum baking treatment are compared experimentally. The results are shown in Table 1. As shown.

Table 1 is a comparison table of IJP red light device data with and without vacuum baking.

Among them, the above-mentioned experiment adopts a vacuum thermal baking with a baking time of 60 minutes, a vacuum pressure of less than 7 × 10 ^-4 Pa, and a temperature of 120 degrees Celsius.

In the above Table 1, the device efficiency (cd / A) is expressed by the luminous flux per unit area, and the brightness is attenuated to 95%, such as 950 nits, under the condition of the initial brightness test of the device at 1000 nits. As shown in Table 1, after the vacuum baking process is performed on an IJP red light device with a chromaticity abscissa of CIEx of 0.66 and a chromaticity ordinate of CIEy of 0.34, the efficiency Eff is compared with that of a device without vacuum baking, Small increases, such as 8% efficiency. However, the device life LT95 has been greatly improved, extending 89%. It can be clearly seen from the above experimental results that the manufacturing method used in this embodiment can significantly prolong the life of the display device.

As shown in FIG. 5, in an embodiment of the organic light emitting display device of the present application, the organic light emitting display device 50 includes: a substrate 501, an anode metal layer 502, a hole injection layer 503, a hole transport layer 504, and light Layer 505, electron transport layer 506, and cathode metal layer 507.

Wherein, the content of residual solvents and / or additives in the hole injection layer 503, the hole transport layer 504, and the light emitting layer 505 is less than a preset threshold.

The preset threshold is a preset value, which can be set according to actual needs, and is not specifically limited here.

For the manufacturing process of the organic light emitting device 50, reference may be made to the manufacturing method of the display device of the present application, which will not be repeated here. Because in the process of preparing the organic light emitting device 50, after all the film layers that require inkjet printing, such as the hole injection layer 503, the hole transport layer 504, and the light emitting layer 505, are formed, and other film layers are formed by vacuum evaporation For example, before the electron transport layer 506 and the cathode metal layer 507. Vacuum baking the substrate after inkjet printing can remove high boiling point solvents or additives remaining in the film layer formed by inkjet printing, thereby reducing the degradation factor of the lifetime of the organic light emitting display device 50 and extending the organic light emitting display. The lifetime of the device 50.

In some embodiments, as shown in FIG. 5, the organic light emitting display device 50 further includes a protective layer 508 and a packaging layer 509 formed on a surface of the cathode metal layer 507 away from the electron transport layer 506.

Of course, in other embodiments, the organic light emitting display device may further include other film layers or components according to requirements, which is not specifically limited herein.

As shown in FIG. 6, in another schematic structural diagram of the organic light emitting display provided in the embodiment of the present application, the organic light emitting display 60 includes: an organic light emitting device 601, and for the structure of the organic light emitting device 601, refer to the organic light emitting device provided in the embodiment of the present application. The structure provided by another structural schematic diagram of the light-emitting display will not be repeated here.

In this embodiment, during the preparation of the organic light emitting display device, after all film layers requiring inkjet printing are formed, and before other film layers are formed by vacuum evaporation. The substrate subjected to inkjet printing is subjected to a vacuum baking process, thereby removing high boiling point solvents or additives remaining in the film layer formed by inkjet printing, reducing the degradation factors of the life of the organic light emitting display device, and thereby extending the life.

The above is only an implementation of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present application, or directly or indirectly applied to other related technologies The fields are equally included in the patent protection scope of this application.

Claims

A method for manufacturing a display device, including:

Providing a substrate;

Forming an anode metal layer on a surface of the substrate;

Forming the hole injection layer on a surface of the anode metal layer remote from the substrate, and curing the hole injection layer by vacuum drying and baking;

Forming the hole transport layer on a surface of the hole injection layer remote from the anode metal layer, and curing the hole transport layer by vacuum drying and baking;

Forming the light emitting layer on a surface of the hole transport layer remote from the hole injection layer, and curing the light emitting layer by vacuum drying and baking;

The substrate provided with the anode metal layer, the hole injection layer, the hole transport layer, and the light emitting layer is baked, and the baking temperature is lower than the temperature at which the hole injection layer, the hole transport layer, and the substrate are formed. Said baking temperature at any one of the light-emitting layers; and

An electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking.
The method according to claim 1, wherein the pressure in the vacuum baking equipment is less than 7 × 10 -4 Pa.
The preparation method according to claim 1, wherein a baking temperature of the vacuum baking device does not exceed 180 degrees Celsius.
The method of claim 1, wherein the step of forming an anode metal layer on a surface of the substrate comprises:

A magnetron sputtering process is used to sputter an indium tin oxide film layer on the surface of the substrate to form the anode metal layer.
The manufacturing method according to claim 1, wherein the step of sequentially forming an electron transport layer and a cathode metal layer on the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, include:

On the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, the electron transport layer and the cathode metal layer are sequentially formed by a vacuum evaporation process.
The method according to claim 1, wherein after the step of sequentially forming an electron transport layer and a cathode metal layer on the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, ,Also includes:

A protective layer and an encapsulating layer are sequentially formed on a surface of the cathode metal layer remote from the electron transport layer.
The method according to claim 1, wherein the cathode metal layer is made of a metal having a low work function or the composite metal having a low work function.
The method according to claim 1, wherein the anode metal layer is made of a material with a high work function and a high light transmittance.
An organic light emitting display device, including:

Substrate

An anode metal layer formed on the substrate;

The hole injection layer is formed on the surface of the substrate by means of inkjet printing, and the hole injection layer is far from the anode metal layer;

A hole transport layer is formed on the hole injection layer by inkjet printing, and the hole transport layer is far from the anode metal layer;

The light-emitting layer is formed on the hole-transporting layer by inkjet printing;

An electron transport layer formed on the light emitting layer after the substrate is vacuum baked, the electron transport layer being far from the hole transport layer; and

A cathode metal layer is formed on the electron transport layer, and the cathode metal layer is far from the hole transport layer.
The organic light emitting display device according to claim 9, further comprising:

A protective layer formed on a surface of the cathode metal layer remote from the electron transport layer; and

An encapsulation layer is formed on the protection layer.
A method for manufacturing a display device, including:

Providing a substrate;

Forming an anode metal layer on a surface of the substrate;

Inkjet printing on the surface of the anode metal layer away from the substrate to sequentially form a stacked hole injection layer, a hole transport layer, and a light emitting layer;

Vacuum baking the substrate after inkjet printing;

An electron transport layer and a cathode metal layer are sequentially formed on a surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking.
The manufacturing method according to claim 11, wherein the step of subjecting the substrate subjected to inkjet printing to a vacuum baking process comprises:

The substrate after inkjet printing is placed in a vacuum baking device and baked for 30 minutes to 180 minutes.
The method according to claim 12, wherein the pressure in the vacuum baking equipment is less than 7 × 10 -4 Pa.
The preparation method according to claim 12, wherein a baking temperature of the vacuum baking device is lower than a baking temperature when forming any one of the hole injection layer, the hole transport layer, and the light emitting layer. temperature.
The preparation method according to claim 14, wherein the baking temperature of the vacuum baking device does not exceed 180 degrees Celsius.
The method according to claim 11, wherein the step of forming an anode metal layer on the surface of the substrate comprises:

A magnetron sputtering process is used to sputter an indium tin oxide film layer on the surface of the substrate to form the anode metal layer.
The manufacturing method according to claim 11, wherein the step of sequentially forming a stacked hole injection layer, a hole transport layer, and a light emitting layer by inkjet printing on a surface of the anode metal layer remote from the substrate comprises:

Forming the hole injection layer on the surface of the anode metal layer away from the substrate by inkjet printing, and curing the hole injection layer by vacuum drying and baking;

Forming the hole transport layer by inkjet printing on a surface of the hole injection layer remote from the anode metal layer, and curing the hole transport layer by vacuum drying and baking; and

The light emitting layer is formed by inkjet printing on a surface of the hole transporting layer remote from the hole injection layer, and the light emitting layer is cured by vacuum drying and baking.
The method according to claim 11, wherein the step of sequentially forming an electron transport layer and a cathode metal layer on the surface of the light-emitting layer of the substrate far from the hole transport layer after the vacuum baking, include:

On the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, the electron transport layer and the cathode metal layer are sequentially formed by a vacuum evaporation process.
The method according to claim 11, wherein after the step of sequentially forming an electron transport layer and a cathode metal layer on the surface of the light emitting layer of the substrate far from the hole transport layer after the vacuum baking, ,Also includes:

A protective layer and an encapsulating layer are sequentially formed on a surface of the cathode metal layer remote from the electron transport layer.