WO2020019566A1

WO2020019566A1 - Flexible display apparatus and preparation method therefor

Info

Publication number: WO2020019566A1
Application number: PCT/CN2018/113577
Authority: WO
Inventors: 谢华飞
Original assignee: 深圳市华星光电半导体显示技术有限公司
Priority date: 2018-07-25
Filing date: 2018-11-02
Publication date: 2020-01-30
Also published as: CN109166881B; CN109166881A

Abstract

A flexible display apparatus and a preparation method therefor. The preparation method comprises the steps of: providing a glass substrate; forming a graphene layer or a graphene oxide layer on the glass substrate by means of transfer printing technology; forming a thin film transistor on the graphene layer or the graphene oxide layer; preparing an organic light emitting device on the thin film transistor; packaging the thin film transistor and the organic light emitting device; and removing the glass substrate to obtain the flexible display apparatus.

Description

Flexible display device and preparation method thereof

Technical field

The present invention relates to the field of flexible display technology, and in particular, to a flexible display device and a manufacturing method thereof.

Background technique

As a new generation of display devices, flexible displays have a wide range of applications in personal digital products, automotive displays, and military fields due to their advantages such as portability, light weight, and resistance to breakage. At present, the main technical difficulty of flexible displays lies in the manufacture of flexible substrates. The existing flexible substrates are thicker, the preparation process is more complicated, and the flexibility and stability are difficult to meet the requirements of flexible displays.

Therefore, the prior art needs to be improved.

technical problem

The invention provides a flexible display device and a method for preparing the same. Using graphene or graphene oxide as a substrate of a flexible display device reduces the difficulty of the manufacturing process, reduces the thickness of the substrate, and realizes the thinning of the flexible display device.

Technical solutions

The invention provides a method for manufacturing a flexible display device. The method includes:

Providing a glass substrate;

Forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology;

Forming a thin film transistor on the graphene layer or the graphene oxide layer;

Preparing an organic light emitting device on the thin film transistor;

Encapsulating the thin film transistor and the organic light emitting device;

The glass substrate is removed to obtain the flexible display device.

In a preferred embodiment, before the graphene layer or the graphene oxide layer is formed on the glass substrate by a transfer technology, the preparation method further includes: surface-treating the glass substrate.

In a preferred embodiment, the surface treatment of the glass substrate specifically includes:

Cleaning the glass substrate;

Surface modification of the cleaned glass substrate;

An initiator is grown on the surface of the glass substrate after the modification treatment.

In a preferred embodiment, cleaning the glass substrate specifically includes:

Etching the glass substrate;

Glass substrate after immersion etching;

Wash and dry the soaked glass substrate.

In a preferred embodiment, the surface modification treatment of the cleaned glass substrate specifically includes:

Glass substrate after immersion cleaning;

The soaked glass substrate was washed with toluene and acetone in this order and dried.

In a preferred embodiment, the glass substrate surface growth initiator after the modification treatment specifically includes:

Rinse the modified glass substrate;

The washed glass substrate was washed with toluene, acetone / water mixed solution, and acetone in this order and dried under vacuum.

In a preferred embodiment, the forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology specifically includes:

Growing a graphene layer or a graphene oxide layer on a transfer substrate;

Spin coating a resin material on the graphene layer or the graphene oxide layer to form an adhesive layer;

Bonding a glass substrate to the adhesive layer;

Remove the transfer substrate.

In a preferred embodiment, the transfer substrate is copper foil, and the resin material is polymethyl methacrylate mixed with cuprous chloride, bipyridine, and a-bromoisobutyric acid ethyl ester.

In a preferred embodiment, removing the glass substrate to obtain the flexible display device includes: immersing and washing with acetone to separate the glass substrate from the graphene layer or graphene oxide layer to obtain the flexible display device.

The present invention further provides a flexible display device, which is prepared by using the aforementioned method.

The present invention further provides a method for manufacturing a flexible display device. The method includes:

Providing a glass substrate and subjecting the glass substrate to surface treatment;

Preparing an organic light emitting device on the thin film transistor;

A surface of the thin film transistor and the organic light emitting device is covered with a protective layer;

Using a packaging structure to package the thin film transistor and the organic light emitting device;

The glass substrate is removed to obtain the flexible display device.

Growing a graphene layer or a graphene oxide layer on a transfer substrate;

Bonding a glass substrate to the adhesive layer;

Remove the transfer substrate.

In a preferred embodiment, nitrogen is filled between the packaging structure and the protective layer.

Beneficial effect

The flexible display device proposed by the present invention uses graphene or graphene oxide as a flexible substrate, which reduces the thickness of the substrate and realizes the thinning of the flexible display device. Since graphene or graphene oxide has better flexibility, stability, and thermal expansion It is beneficial to simplify the manufacturing process of the flexible display device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a flexible display device;

2 is a schematic structural diagram of a thin film transistor;

3a to 3h are flowcharts of a method for manufacturing a flexible display device.

Best Mode of the Invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand various embodiments of the invention and various modifications as are suited to a particular intended application. In the drawings, the same reference numerals will always be used to represent the same elements.

Referring to FIG. 1, the flexible display device in this embodiment includes a flexible substrate 1, a thin film transistor 2, an organic light emitting device 3, and a packaging structure 4. The material of the flexible substrate 1 is graphene or graphene oxide. The thin film transistor 2 is provided on the flexible substrate 1, the organic light emitting device 3 is provided on the thin film transistor 2, and the packaging structure 4 is used for packaging the thin film transistor 2 and the organic light emitting device 3.

2, specifically, the thin film transistor 2 includes a substrate 21, a buffer layer 22, a gate 23, a gate insulating layer 24, an active layer 25, a source 26, a drain 27, a passivation layer 28, and a pixel electrode layer 29. . The flexible substrate 1 is the substrate 21 of the thin film transistor 2. The buffer layer 22 is provided on the flexible substrate 1. Among them, the structure of the thin film transistor 2 is a bottom gate structure, the gate 23 is provided on the buffer layer 22, and the gate insulating layer 24 covers The gate 23 and the active layer 25 are provided on the gate insulating layer 24 and corresponding to the gate 23. The source 26 and the drain 27 are located at two ends of the active layer 25 and are connected to the active layer 25 respectively, as shown in FIG. 1. As shown, the source electrode 26 is located at one end of the active layer 25 and covers the edge of the active layer 25, and the drain electrode 27 is located at the other end of the active layer 25 and covers the edge of the active layer 25. The passivation layer 28 is disposed on the source electrode 26 and the drain electrode 27 and covers the source electrode 26 and the drain electrode 27. The passivation layer 28 protects the source electrode 26 and the drain electrode 27. The pixel electrode layer 29 is disposed on the passivation layer 28 and is connected to the drain electrode 27 through a via hole. The material of the pixel electrode layer 29 is ITO.

Referring again to FIG. 1, the organic light emitting device 3 includes a first electrode 31, a hole injection layer 32, a hole transport layer 33, a light emitting layer 34, an electron transport layer 35, an electron injection layer 36, and a second electrode 37. The pixel electrode layer 29 serves as the first electrode 31 of the organic light emitting device 3, and the hole injection layer 32, the hole transport layer 33, the light emitting layer 34, the electron transport layer 35, the electron injection layer 36, and the second electrode 37 move away from the first The directions of the electrodes 31 are sequentially stacked on the first electrode 31.

The flexible display device in this embodiment further includes a protective layer 5. The protective layer 5 has a function of blocking water vapor and oxygen, and covers the surfaces of the thin film transistor 2 and the organic light emitting device 3. The protective layer 5 is mainly used to protect the thin film transistor 2. The film layer of the middle buffer layer 22 or more, and therefore, the protective layer 5 covers the surface of the film layer above the buffer layer 22. The protective layer 5 may be formed by alternately stacking inorganic and organic materials.

The packaging structure 4 is covered outside the protective layer 5, and a protective gas is filled between the packaging structure 4 and the protective layer 5. The protective gas in this embodiment is nitrogen.

Referring to FIGS. 3a to 3h, this embodiment further provides a method for manufacturing the foregoing flexible display device. The method includes the following steps:

S1, providing a glass substrate 10;

S2. A graphene layer or a graphene oxide layer is formed on the glass substrate 10 by a transfer technology, and the graphene layer or the graphene oxide layer is the flexible substrate 1, as shown in FIGS. 3a to 3d;

S3. A thin film transistor is formed on the graphene layer or the graphene oxide layer to obtain a thin film transistor 2, as shown in FIG. 3e;

S4. An organic light emitting device 3 is prepared on the thin film transistor 2, as shown in FIG. 3f;

S5. Package the thin film transistor 2 and the organic light emitting device 3, as shown in FIG. 3g;

S6. The glass substrate 10 is removed to obtain a flexible display device, as shown in FIG. 3h.

Specifically, step S2 includes:

S21. A graphene layer or a graphene oxide layer is grown on the transfer substrate 20, as shown in FIG. 3a;

S22. Spin-coat a resin material on the graphene layer or the graphene oxide layer to form an adhesive layer 30, as shown in FIG. 3b;

S23. Bond the glass substrate 10 and the adhesive layer 30, as shown in FIG. 3c;

S24. Remove the transfer substrate 20, as shown in FIG. 3d.

Preferably, the transfer substrate 20 is a copper foil, the process used to grow the graphene layer or the graphene oxide layer is a chemical vapor deposition (CVD) process, and the resin material is mixed with cuprous chloride (CuCl), bipyridine, a-bromoisobutyric acid polymethyl methacrylate (PMMA), the glass substrate 10 and the adhesive layer 30 are adhered by a heat curing process, so that the glass substrate 10 and the graphene layer are adhered by the adhesive layer 30 Or the graphene oxide layer is adhered.

In step S24, the transfer substrate 20 is dissolved by a copper etching solution, and the glass substrate 10 on which the graphene layer or the graphene oxide layer is formed is taken out and rinsed with water to dry, thereby the graphene layer or the graphene oxide layer is dried. Transfer onto the glass substrate 10.

In order to enable better adhesion between the glass substrate 10 and the adhesive layer 30, before step S2, the preparation method further includes:

S20. Surface treatment is performed on the glass substrate 10.

Specifically, step S20 includes:

S201, cleaning the glass substrate 10;

S202. Perform surface modification treatment on the cleaned glass substrate;

S203. A growth initiator on the surface of the glass substrate after the modification treatment.

Step S201 specifically includes: etching the glass substrate, wherein the etching solution is a 5% hydrofluoric acid solution, and the etching time is 5-20 minutes; and then immersing the etched glass substrate, the soaking solution is a 20% hydrochloric acid solution, and the soaking time is 1 ~ 2h; Finally, the soaked glass substrate is washed and dried.

Step S202 specifically includes: immersing and cleaning the glass substrate, wherein the immersion solution is a mixed solution of toluene and y-aminopropyltriethoxysilane (KH550), the immersion temperature is 100 to 120 ° C, and the immersion time is 2 to 4 hours ; Wash and dry the soaked glass substrate with toluene, acetone in order.

Step S203 specifically includes: rinsing the modified glass substrate; rinsing against light; the rinsing solution is a mixed solution of toluene, a-bromoisobutyryl bromide, and triethylamine; the rinsing time is 2 to 4 hours; The washed glass substrate was washed with acetone / water mixture, acetone and vacuum dried.

In step S3, SiNx / SiO2 is sequentially grown as a buffer layer 22 on the graphene layer or the graphene oxide layer, that is, the substrate 21 by a CVD process, and a first metal is deposited on the buffer layer 22 by a physical vapor deposition (PVD) process. Layer (not shown), apply photoresist on the first metal layer, obtain the pattern of the gate electrode 23 through exposure and development processes, and then use an acid etching solution to obtain the gate electrode 23, and then the gate electrode 23 The photoresist is peeled off; the gate insulating layer 24 and the semiconductor material layer (not shown) are sequentially deposited on the gate electrode 23; the semiconductor material layer is patterned to obtain the active layer 25; and a second metal layer is deposited on the active layer 25 (Not shown), a photoresist is coated on the second metal layer, and the patterns of the source 26 and the drain 27 are obtained through exposure and development processes, and then the source 26 and the drain are obtained by etching with an acid etching solution 27, and then remove the photoresist on source 26 and drain 27; passivation layer 28 and pixel electrode layer 29 are sequentially deposited on source 26 and drain 27, and pixel electrode layer 29 passes through via and drain 27 Connected, thereby obtaining a thin film transistor 2.

In step S4, a hole injection layer 32, a hole transport layer 33, a light emitting layer 34, an electron transport layer 35, an electron injection layer 36, a second electrode 37, a protective layer 5, and a pixel electrode are sequentially deposited on the pixel electrode layer 29. The layer 29 is the first electrode 31, so that the organic light emitting device 3 is obtained.

In step S5, a package structure 4 is provided on the outside of the thin film transistor 2 and the organic light emitting device 3. The package structure 4 is covered on the outside of the protective layer 5, and a protective gas is filled between the package structure 4 and the protective layer 5, thereby achieving flexibility. For the packaging of the display device, the protective gas in this embodiment is nitrogen.

In step S6, the method used to remove the glass substrate 10 is a chemical method, specifically, soaking the flexible display device in step S5 by immersion in acetone, and the adhesive layer 30 between the glass substrate 10 and the graphene layer or graphene oxide layer. It is dissolved in acetone, so that the glass substrate 10 is separated from the graphene layer or the graphene oxide layer, and then taken out and dried, and finally a flexible display device using the graphene layer or the graphene oxide layer as a substrate is obtained. Compared with laser peeling or mechanical peeling methods, chemical peeling can effectively reduce the damage to the flexible display device caused by laser peeling or mechanical peeling.

The flexible display device proposed in this embodiment uses graphene or graphene oxide as the flexible substrate 1, which reduces the thickness of the substrate and realizes the thinning of the flexible display device. Furthermore, since graphene or graphene has better flexibility and stability, Properties and thermal expansion properties, thereby reducing the thickness of the flexible display device and simplifying the manufacturing process of the flexible display device.

In summary, although the present invention has been disclosed as above with preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications without departing from the spirit and scope of the present invention. This kind of modification and retouching, therefore, the protection scope of the present invention is subject to the scope defined by the claims.

Claims

A method for manufacturing a flexible display device. The method includes:

Providing a glass substrate;

Forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology;

Forming a thin film transistor on the graphene layer or the graphene oxide layer;

Preparing an organic light emitting device on the thin film transistor;

Encapsulating the thin film transistor and the organic light emitting device;

The glass substrate is removed to obtain the flexible display device.
The method according to claim 1, wherein before the graphene layer or the graphene oxide layer is formed on the glass substrate by a transfer technology, the method further comprises: surface-treating the glass substrate.
The method according to claim 2, wherein the surface-treating the glass substrate comprises:

Cleaning the glass substrate;

Surface modification of the cleaned glass substrate;

An initiator is grown on the surface of the glass substrate after the modification treatment.
The method according to claim 3, wherein the cleaning the glass substrate comprises:

Etching the glass substrate;

Glass substrate after immersion etching;

Wash and dry the soaked glass substrate.
The method according to claim 3, wherein the surface modification treatment of the cleaned glass substrate specifically comprises:

Glass substrate after immersion cleaning;

The soaked glass substrate was washed with toluene and acetone in this order and dried.
The preparation method according to claim 3, wherein the glass substrate surface growth initiator after the modification treatment specifically comprises:

Rinse the modified glass substrate;

The washed glass substrate was washed with toluene, acetone / water mixed solution, and acetone in this order and dried under vacuum.
The method according to claim 1, wherein the forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology specifically comprises:

Growing a graphene layer or a graphene oxide layer on a transfer substrate;

Spin coating a resin material on the graphene layer or the graphene oxide layer to form an adhesive layer;

Bonding a glass substrate to the adhesive layer;

Remove the transfer substrate.
The method according to claim 7, wherein the transfer substrate is copper foil, and the resin material is polymethacrylic acid mixed with cuprous chloride, bipyridine, and a-bromoisobutyric acid ethyl ester Methyl ester.
The method according to claim 8, wherein removing the glass substrate and obtaining the flexible display device comprises: immersing and washing with acetone to separate the glass substrate from the graphene layer or graphene oxide layer to obtain the Flexible display device.
A flexible display device, wherein the flexible display device is prepared by the method according to claim 1.
A method for manufacturing a flexible display device. The method includes:

Providing a glass substrate and subjecting the glass substrate to surface treatment;

Forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology;

Forming a thin film transistor on the graphene layer or the graphene oxide layer;

Preparing an organic light emitting device on the thin film transistor;

A surface of the thin film transistor and the organic light emitting device is covered with a protective layer;

Using a packaging structure to package the thin film transistor and the organic light emitting device;

The glass substrate is removed to obtain the flexible display device.
The method according to claim 11, wherein the forming a graphene layer or a graphene oxide layer on a glass substrate by a transfer technology specifically comprises:

Growing a graphene layer or a graphene oxide layer on a transfer substrate;

Spin coating a resin material on the graphene layer or the graphene oxide layer to form an adhesive layer;

Bonding a glass substrate to the adhesive layer;

Remove the transfer substrate.
The method according to claim 12, wherein the transfer substrate is copper foil, and the resin material is polymethacrylic acid mixed with cuprous chloride, bipyridine, and a-bromoisobutyric acid ethyl ester. Methyl ester.
The method of claim 11, wherein nitrogen is filled between the package structure and the protective layer.