CN114078903B

CN114078903B - Electroluminescent devices and display devices

Info

Publication number: CN114078903B
Application number: CN202011642376.4A
Authority: CN
Inventors: 李松举; 孙贤文; 付东
Original assignee: Guangdong Juhua Printing Display Technology Co Ltd
Current assignee: Guangdong Juhua Printing Display Technology Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2025-07-11
Anticipated expiration: 2040-12-31
Also published as: CN114078903A

Abstract

The present invention discloses an electroluminescent device, characterized in that it comprises: a first encapsulation layer, which is arranged around a light-emitting area; a dam layer, which is arranged on one side of the first encapsulation layer, and a groove is formed between the dam layers to expose the light-emitting area; a light-emitting functional body, which is arranged in the light-emitting area; a second encapsulation layer, which covers the dam layer and the light-emitting functional body as a whole; a buffer layer, which is arranged on a side of the second encapsulation layer away from the light-emitting functional body and filled in the groove; and a third encapsulation layer, which is arranged on a side of the buffer layer away from the second encapsulation layer. In the electroluminescent device, the buffer layer coated on the entire surface in the traditional technology is designed as separate buffer layers, which can reduce the required thickness of the buffer layer. While reducing the thickness of the buffer layer, the overall bending resistance of the flexible electroluminescent device can also be ensured.

Description

Electroluminescent device and display device

Technical Field

The invention relates to the technical field of flexible device preparation, in particular to an electroluminescent device, a display device and application.

Background

Conventional flat panel displays typically have two layers of hard glass substrates and light emitting elements and other components located between the hard glass substrates, which are capable of only planar based display. Flexible display screens typically replace the hard glass substrate in conventional display screens with a flexible substrate and flexible encapsulation layers, and incorporate improvements in the light emitting elements and other components therein to enable flexible or foldable display effects. The flexible display screen can bring richer use performance, and provides more possibility for the form of the electronic equipment, so that the flexible display screen gradually becomes one of key projects for research of various manufacturers.

The conventional light emitting elements are extremely sensitive to water and oxygen and are easily affected by water and oxygen to fail, so that the encapsulation layers are required to have a strong water and oxygen blocking capability, for example, 10 ^-6g/cm² ·day is required. In addition, the flexible display screen can face more frequent bending operation in practical application, so that the packaging layer in the flexible display screen also faces frequent bending. On one hand, in order to avoid fracture when frequently bending, the internal stress of the packaging layer is not easy to be too large, and on the other hand, the frequent bending can cause local defects of the packaging layer, so that the water-oxygen barrier capability is reduced.

In order to achieve both the water-oxygen barrier capability and the bending resistance capability, a structure in which inorganic water-oxygen barrier layers and organic buffer layers are alternately stacked is often used as the encapsulation layer in the conventional art. The inorganic water-oxygen barrier layer plays a role in effectively blocking water and oxygen, the organic buffer layer plays a role in buffering deformation, and the internal stress of the whole packaging layer is reduced as much as possible. Due to the precision of the preparation process, foreign matters or pinhole-shaped defects often appear in the packaging layer locally, the foreign matters or defects become invasion points of water and oxygen and gradually diffuse, and a deterioration area in the packaging layer is continuously expanded and finally evolves into serious quality defects. An organic buffer layer is therefore required to cover the foreign matter and vacuum, providing a planar encapsulation surface for the inorganic water-oxygen barrier layer. The thickness of the organic buffer layer is generally required to be 10-20 μm to achieve effective foreign matter coverage and meet the requirement of packaging yield. However, thicker organic buffer layers also reduce the bend radius and bend tolerance of the flexible display screen. For the above reasons, it is often difficult to simultaneously satisfy the bending property and the barrier property of the flexible display screen.

Disclosure of Invention

In view of this, the present invention provides an electroluminescent device with good barrier property and bending property, and correspondingly provides a display device.

According to one embodiment of the present invention, an electroluminescent device includes:

A first encapsulation layer disposed around the light emitting region;

A bank layer disposed at one side of the first encapsulation layer, grooves being formed between the bank layers to expose the light emitting region;

a light-emitting function body disposed within the light-emitting region;

A second encapsulation layer integrally covering the bank layer and the light emitting function body;

The buffer layer is arranged on one side, far away from the luminous functional main body, of the second packaging layer and is filled in the groove;

and the third packaging layer is arranged on one side of the buffer layer away from the second packaging layer.

In one embodiment, the light emitting areas are plural, and the plural light emitting areas are distributed in plural columns, and the dam layer is disposed on the first encapsulation layer between the light emitting areas of adjacent columns.

In one embodiment, the second encapsulation layer includes a plurality of sub-encapsulation layers stacked in a direction from the first encapsulation layer to the third encapsulation layer.

In one embodiment, the LED further comprises a substrate, wherein the first packaging layer is arranged on the substrate, the dykes and dams layer is arranged on one side of the first packaging layer far away from the substrate, and the luminous functional main body comprises a first electrode, a second electrode and a luminous functional layer, wherein the first electrode and the second electrode are oppositely arranged;

The substrate is provided with a thin film transistor and a first electric connection hole, a first electric conductor is filled in the first electric connection hole, one end of the first electric conductor is electrically connected with a drain electrode in the thin film transistor, and the other end of the first electric conductor is electrically connected with the first electrode.

In one embodiment, a common electrode and a second electric connection hole are arranged in the substrate, a third electric connection hole is arranged in the first packaging layer, a second electric conductor is filled in the second electric connection hole, a third electric conductor is filled in the third electric connection hole, and the second electrode is electrically connected to the common electrode through the second electric conductor and the third electric conductor.

In one embodiment, the thickness of the first encapsulation layer is 0.5-2 μm, and/or

The thickness of the dyke layer is 1-6 mu m, and/or

The thickness of the second packaging layer is 0.5-2 mu m.

In one embodiment, the height difference between the surface of the buffer layer on the side far away from the second encapsulation layer and the surface of the second encapsulation layer on the side far away from the dyke layer is less than or equal to 0.3 μm.

In one embodiment, the materials of the first, second and third encapsulation layers are each independently selected from one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium dioxide, hafnium oxide, zinc oxide, magnesium oxide and zirconium oxide, and/or

The material of the dyke layer is selected from polyimide, and/or

The material of the buffer layer is selected from one or more of silicon carbonitride, silicon oxycarbide, fluorinated silicon carbonitride, polydimethylsiloxane, parylene, polypropylene, polystyrene and polyimide.

A display device comprising an electroluminescent device as described in any one of the embodiments above.

In one embodiment, the display device is a cell phone, a television, a tablet, a display screen, a VR device, an AR device, a computer, or an in-vehicle display.

The conventional whole encapsulation layer depends on the form that inorganic encapsulation layers and organic encapsulation layers are alternately laminated so as to have a bendable property while maintaining a barrier property, and the organic encapsulation layer releases stress generated when the inorganic encapsulation layer is bent as much as possible while avoiding defects caused by foreign matters.

The electroluminescent device in the above embodiment is different from the conventional whole-surface encapsulation layer, and a discrete encapsulation structure is proposed. The discrete packaging structure is designed for the structure of the dyke layer and corresponds to the luminous functional main body and the specific preparation process thereof, and the structure of the multi-layer packaging layer is designed to form the package type packaging of the luminous functional main body. In the part without the buffer layer, even if each packaging layer generates defects or cracks, the invasion of water and oxygen can be effectively blocked. In addition, the buffer layer coated on the whole surface in the prior art is designed into separate buffer layers, so that the thickness of the buffer layer can be reduced, and the bending resistance of the whole flexible electroluminescent device can be ensured while the thickness of the buffer layer is reduced.

In addition, the buffer layer is changed into a discrete type and is filled in the concave between the dykes and dams, so that the flatness of the flexible electroluminescent device can be ensured as much as possible, and the probability of occurrence of the Mura problem is greatly reduced. Meanwhile, the height of the bank layer of the flexible electroluminescent device in the above embodiment can be set higher, thereby avoiding bad defects such as bridging and the like generated in the printing process of the OLED material.

Drawings

FIG. 1 is a schematic cross-sectional view of a flexible electroluminescent device according to an embodiment;

fig. 2 is a schematic cross-sectional structure of step S1 in the process of manufacturing a flexible electroluminescent device;

FIG. 3 is a schematic cross-sectional view of step S2 in the process of fabricating a flexible electroluminescent device;

fig. 4 is a schematic cross-sectional structure of step S3 in the process of manufacturing the flexible electroluminescent device;

Fig. 5 is a top view of step S3 in the process of manufacturing a flexible electroluminescent device;

fig. 6 is a schematic cross-sectional structure of step S4 in the process of manufacturing the flexible electroluminescent device;

fig. 7 is a schematic cross-sectional structure of step S5 in the process of manufacturing the flexible electroluminescent device;

fig. 8 is a schematic cross-sectional structure of step S6 in the process of manufacturing the flexible electroluminescent device;

Fig. 9 is a schematic cross-sectional structure of step S7 in the process of manufacturing the flexible electroluminescent device.

Wherein, each reference numeral and meaning are as follows:

110, a substrate; 111, a thin film transistor; 112, a first conductor, 113, a common electrode, 114, a second conductor, 120, a first packaging layer, 131, a first electrode, 132, a light emitting function layer, 133, a second electrode, 140, a dyke layer, 150, a second packaging layer, 160, a buffer layer, 170, a third packaging layer, and 180, a third electrode.

Detailed Description

In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. As used herein, "multiple" means a combination of two or more items. The concept of the ratio or concentration in the present application is considered to be the mass ratio or mass concentration unless explicitly stated or not generally understood by those skilled in the art.

The barrier layer in the conventional flexible light emitting device generally adopts a mode of alternately laminating organic/inorganic film layers, however, such barrier layers are difficult to combine the bending resistance and the barrier performance of the flexible device. In order to enhance the barrier properties of the flexible light emitting device while ensuring the bending resistance properties as much as possible, one embodiment of the present invention provides a flexible electroluminescent device incorporating a barrier layer, which includes at least:

a first encapsulation layer disposed around the light emitting region;

The dykes and dams layer is arranged on one side of the first packaging layer, grooves are formed between the dykes and dams layer, and the luminous area is exposed;

a light-emitting function body disposed in the light-emitting region;

the second packaging layer integrally covers the dyke layer and the luminous functional main body;

the buffer layer is arranged on one side of the second packaging layer far away from the luminous functional main body and is filled in the groove;

And the third packaging layer is arranged on one side of the buffer layer far away from the second packaging layer.

In one specific example, the first encapsulation layer is disposed on the substrate, and the bank layer is disposed on a side of the first encapsulation layer away from the substrate.

Specifically, for ease of understanding and implementation of this embodiment, please refer to FIG. 1, a flexible electroluminescent device 10 includes a substrate 110, a first encapsulation layer 120, a light emitting function body 130, a bank layer 140, a second encapsulation layer 150, a buffer layer 160, and a third encapsulation layer 170.

Specifically, the substrate 110 is provided with a patterned first encapsulation layer 120, and the first encapsulation layer 120 defines a light emitting region for providing the light emitting functional body 130. The light emitting function body 130 is disposed on the substrate 110 and located in a light emitting region defined by the first encapsulation layer 120.

A bank layer 140 is disposed on a side surface of the first encapsulation layer 120 remote from the substrate 110. Grooves are formed between the bank layers 140 to expose the light emitting region.

The second encapsulation layer 150 entirely covers the bank layer 140 and the light emitting function body 130. Specifically, the second encapsulation layer 150 covers the surface of the bank layer 140, which is not disposed in contact with the first encapsulation layer 120, and extends to cover a side surface of the light emitting function body 130, which is remote from the substrate 110. Further, the second encapsulation layer 150 covers the entire surface on the substrate 110 having the first encapsulation layer 120, the bank layer 140, and the light emitting function body 130.

The light emitting function body 130 is formed in a light emitting region defined by the first encapsulation layer 120, the bank layers 140 are disposed on the first encapsulation layer 120, and since grooves are formed between the bank layers 140, the second encapsulation layer 150 covering the light emitting function body 130 is lower than the second encapsulation layer 150 covering the bank layers 140, and grooves are formed between the second encapsulation layers 150 covering adjacent bank layers 140. Thus, a buffer layer 160 filling the recess is further provided on a side surface of the second encapsulation layer 150 remote from the light emitting function body 130.

The third encapsulation layer 170 is disposed on a side surface of the buffer layer 160 remote from the second encapsulation layer 150. Further, in one specific example, the third encapsulation layer 170 is further disposed on a side surface of the second encapsulation layer 150 remote from the bank layer 140, when the buffer layer 160 is not disposed on the side surface of the second encapsulation layer 150 remote from the bank layer 140.

In one specific example, the light emitting function body 130 includes a first electrode 131, a light emitting function layer 132, and a second electrode 133, which are sequentially stacked. The first electrode 131 is disposed on the substrate 110 and has a portion located in the light emitting region.

For example, the light emitting functional layer 132 may include a liquid crystal display layer, and the first electrode 131 and the second electrode 133 are part of upper and lower electrodes that drive liquid crystal movement. As another example, in one specific example, the light emitting functional layer 132 may include a light emitting layer, which may be selected from an organic light emitting layer and a quantum dot light emitting layer, and the first electrode 131 and the second electrode 133 function to inject holes and electrons, respectively.

In one specific example, the first electrode 131 is an anode for connecting to a positive electrode of an external power source.

In one specific example, the first electrode 131 may be selected from a film layer formed of one of a metal oxide conductive material, an organic conductive material, a conductive metal, and an alloy thereof, or a multi-layered film layer structure formed of a plurality of kinds. The metal oxide conductive material may be selected from ITO (indium tin oxide), IZO (indium zinc oxide), etc., the organic conductive material may be selected from PEDOT (3, 4-ethylenedioxythiophene monomer), and the conductive metal may be selected from aluminum, molybdenum, titanium, copper, silver, gold, etc.

Further, if the light emitting functional layer 132 is a top emission structure, i.e., light is emitted from the light emitting region, the first electrode 131 may be an ITO/Ag/ITO laminated structure in which an Ag plating layer serves as a light reflecting layer to reflect light emitted from the light emitting functional layer 132 toward the light emitting region. The ITO serves to match the work functions of the hole injection and transport layers in the light-emitting functional layer 132, so that holes are better injected into the light-emitting functional layer 132, which is advantageous for improving the overall efficiency of the light-emitting functional body.

In one specific example, the second electrode 133 is a cathode, which functions like an anode, functions as an electrical connection, and electrons are injected into the light emitting function layer 132 through the cathode. The second electrode 133 may also be selected from a film layer formed of one of a metal oxide conductive material, an organic conductive material, a conductive metal, and an alloy thereof, or a multi-layer film layer structure formed of a plurality of kinds. The metal oxide conductive material may be selected from ITO (indium tin oxide), IZO (indium zinc oxide), etc., the organic conductive material may be selected from PEDOT (3, 4-ethylenedioxythiophene monomer), and the conductive metal may be selected from aluminum, molybdenum, titanium, copper, silver, gold, etc. Further, the second electrode 133 is a top emission structure corresponding to the light emitting function layer 132, and has high transparency, high conductivity, and relatively stable film thickness.

In one specific example, the light-emitting functional layer 132 further includes therein a hole functional layer disposed between the anode and the light-emitting layer, and the hole functional layer includes at least one of a hole injection layer and a hole transport layer.

In one specific example, the light emitting functional layer 132 further includes therein an electron functional layer disposed between the cathode and the light emitting layer, the electron functional layer including at least one of an electron injection layer and an electron transport layer.

In one specific example, the substrate 110 is further provided with a thin film transistor 111 and a first electrical connection hole, the first electrical connection hole is filled with a first electrical conductor 112, one end of the first electrical conductor 112 is electrically connected to a drain electrode in the thin film transistor 111, and the other end is electrically connected to the first electrode 131. The first electrode 131 is electrically connected to the drain electrode of the thin film transistor 111 through the first conductor 112, and since the first conductor 112 is disposed inside the substrate 110, the first electrode 131 is not required to be connected to the thin film transistor through a lead connected to the outside, so that an additional lead path is not required to be formed in the first packaging layer 120, which saves the manufacturing process and can maintain the integrity of the first packaging layer 120.

In one specific example, the substrate 110 is further provided with a common electrode 113 and a second electrical connection hole, the first encapsulation layer 120 is provided with a third electrical connection hole, the second electrical connection hole is filled with the second electrical conductor 114, the third electrical connection hole is filled with the third electrical conductor 121, and the second electrode 133 is electrically connected to the common electrode 113 through the second electrical conductor 114 and the third electrical conductor 121. The common electrode 113 is also disposed inside the substrate 110, and the second electrode 133 is electrically connected to the common electrode 113 through the second conductor 114 and the third conductor 121 inside the device, respectively, so that the integrity of the first package layer 120 and/or the second package layer 150 can be maintained without forming an additional wiring path.

In one specific example, a third electrode 180 contacting the second conductor 114 and the third conductor 121 and spaced apart from the first electrode 131 is further provided on the substrate 110. The third electrode 180 may serve as a contact for the second conductor 114 and the third conductor 121, electrically communicating the second conductor 114 and the third conductor 121. In general, the film forming region of the second electrode 133 is an overall film coating of the display region, and the connection leads of the film forming region and the array conductive traces of the thin film transistor 111 are disposed at the periphery of the display region, and are connected to the TFT circuit through a large-area cathode overlap region (including via holes and exposed electrode structures), so as to finally form a circuit to light the light emitting functional layer 132. In this case, the first encapsulation layer 120 and/or the second encapsulation layer 150 need to be provided with a channel for the leads, which is equivalent to reserving defect holes, so that the flexible electroluminescent device 10 of this embodiment cannot achieve perfect encapsulation. The second conductor 114, the third conductor 121 and the common electrode 113 are all disposed inside the device, and the second electrode 133 can be directly connected to the common electrode 113 through the inside of the device by means of the second conductor 114 and the third conductor 121, thereby effectively avoiding forming a hole inside the device, which is communicated with the outside.

In one specific example, the first encapsulation layer 120 is a water-oxygen barrier layer that acts as a water-oxygen barrier. The material of the water-oxygen barrier layer should avoid using a material having too high hydrophobicity, because the too high hydrophobicity of the first encapsulation layer 120 may prevent the ink from flowing in the light emitting region, resulting in an uneven flow of the ink in the light emitting region and thus an uneven filling of the material into the gaps between the first encapsulation layers 120, resulting in a defect of uneven light emission. Specifically, the material of the water oxygen barrier layer may be selected from inorganic materials, for example, may be one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, hafnium oxide, zinc oxide, magnesium oxide, and zirconium oxide. More preferably, the material of the water oxygen barrier layer is selected from the group consisting of silicon oxynitride films. The number of oxygen atoms in the silicon oxynitride material can be adjusted, so that the hydrophilicity and hydrophobicity of the water-oxygen barrier layer can be adjusted. The water-oxygen barrier layer may be prepared by plasma chemical vapor deposition, atomic layer deposition, ion beam deposition, magnetron sputtering deposition, or the like. More preferably, the method of preparing the water-oxygen barrier layer is plasma chemical vapor deposition.

In one embodiment, the thickness of the first encapsulation layer 120 is 0.5 μm to 2 μm. Further, the thickness of the first encapsulation layer 120 should be thicker than the thickness of the light emitting function layer 132 in the light emitting function body 130.

The bank layer 140 can be provided as a separate wall between the different light emitting functional bodies 130, and after the bank layer 140 is provided, when each film layer of the light emitting functional body 130 is prepared by a solution method such as ink jet printing, the ejected ink can be limited to a light emitting region and a light emitting region by the higher bank layer 140.

In one specific example, a plurality of light emitting regions are disposed on the substrate 110, and the plurality of light emitting regions are distributed in a plurality of columns, and the bank layer 140 is disposed on the first encapsulation layer 120 between the light emitting regions of adjacent columns. The flexible electroluminescent device 10 comprises a plurality of columns of light-emitting functional bodies 130. The bank layer 140 is disposed only between the light emitting regions of the adjacent columns. Further, the bank layers 140 between the light emitting areas of the adjacent columns are continuous bank layers 140, i.e., line-type bank layers 140. The linear bank layer 140 actually defines a row of a plurality of pixel light emitting units, and the ink-jet manner can be changed from the ink-jet printing one by one to the linear printing, which can reduce the accuracy of the ink-jet device in the linear printing direction, reduce the accuracy requirement for the device, and thus reduce the cost.

In one specific example, the material of the bank layer 140 may be selected from organic materials, such as polyimide. In actual preparation, the polyimide can be coated and patterned by adopting the methods of gluing, exposing and developing.

On the other hand, in the conventional art, the height of the bank layer is required to be as low as possible for the encapsulation layer that needs to be provided on the surface of the flexible device. This is because the higher the height, the more easily the encapsulation layer is subjected to a condition of low film thickness at the side walls and corners of the bank layer, and in severe cases, peeling occurs directly, causing significant defects, leading to package failure. However, in the flexible electroluminescent device 10 provided in the present embodiment, since the separate encapsulation mode is adopted, the bank layer 140 can be set higher, and bridging phenomenon between adjacent light emitting function bodies 130 caused by ink overflow during printing is prevented. This is because the buffer layer 160 is correspondingly provided in the flexible electroluminescent device 10 of the present embodiment. Specifically, after the second encapsulation layer 150 is prepared, the buffer layer 160 substantially fills up the light emitting area between the bank layers 140, which can buffer the stress of each encapsulation layer, and simultaneously cover the foreign object defect on the second encapsulation layer 150, and planarize the surface of the device, so that the third encapsulation layer 170 positioned at the uppermost can be deposited on a relatively flat plane, thereby effectively improving the reliability of the encapsulation.

In one specific example, the thickness of the bank layer is 1 μm to 6 μm. Further, the thickness of the bank layer is 3 μm to 6 μm.

The second encapsulation layer 150 is a water-oxygen barrier layer. Specifically, the material of the second encapsulation layer 150 may be selected from inorganic materials, for example, may be one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, hafnium oxide, zinc oxide, magnesium oxide, and zirconium oxide. More preferably, the material of the second encapsulation layer 150 is selected from silicon oxynitride film. The water-oxygen barrier layer may be prepared by plasma chemical vapor deposition, atomic layer deposition, ion beam deposition, magnetron sputtering deposition, or the like. More preferably, the method of preparing the water-oxygen barrier layer is plasma chemical vapor deposition.

The second encapsulation layer 150 mainly plays a role of isolating water and oxygen. Meanwhile, since the second barrier layer 150 covers the light emitting function body 130, its thickness should be generally set to be thin to have a high visible light transmittance. In one embodiment, the thickness of the second encapsulation layer 150 is 0.5 μm to 2 μm, and further, the thickness of the second encapsulation layer 150 is 0.5 μm to 1 μm.

Since the second encapsulation layer 150 covers both the bank layer 140 and the light emitting function body 130, and there is a relatively remarkable height fluctuation between the bank layer 140 and the light emitting function body 130, the water-oxygen barrier layer generally has a relatively large internal stress, and is not easy to completely cover foreign matters existing on the encapsulation surface. The thin film thickness is easily thinned and broken at the tip of the foreign matter and the bottom of the step with negative slope angle, and especially when the thin film is applied to a flexible display, the packaging thin film is easily broken and peeled off or cracks are generated at the places with the foreign matter, so that the packaging is invalid. The present embodiment is further provided with a buffer layer 160 and a third encapsulation layer 170.

The buffer layer 160 is selected from a soft, low internal stress film material to planarize the device surface as much as possible. In addition, the buffer layer 160 should also have high transmittance. The material may be selected from inorganic materials having properties close to those of organic substances, such as one or more of silicon carbonitride, silicon oxycarbide, fluorinated silicon oxycarbide and fluorinated silicon carbonitride, or the material may be selected from polymeric materials, such as one or more of polydimethylsiloxane, parylene, polypropylene, polystyrene and polyimide.

The main function of the buffer layer 160 is to buffer the stress of the upper and lower layers, so that the device has better reliability and bending resistance. In addition, the buffer layer 160 can also cover impurity particles possibly adhered in the packaging process, so that the edges and corners of the particles are more round, a channel through which water and oxygen permeate is not easy to form, and the water and oxygen barrier performance is certain. The preparation method may be selective coating technology such as ink-jet printing, nano transfer printing, etc. or coating technology, and preferably, the buffer layer 160 is prepared by an ink-jet printing method. Ink is dropped at the spaces between the banks 170 using an inkjet printing method, and the thickness of the formed film layer is controlled to be equivalent to the height of the bank layer.

In one specific example, the buffer layer 160 may extend to cover the surface of the second encapsulation layer 150 on the bank layer 140.

In one specific example, the thickness of the buffer layer 160 should be set to match the thickness of the bank layer 140 such that a surface of the side of the buffer layer 160 remote from the second encapsulation layer 150 is level with the surface of the second encapsulation layer 150 on the bank layer 140 or slightly higher than the surface of the second encapsulation layer 150 on the bank layer 140. Specifically, the height difference between the surface of the buffer layer 160 on the side away from the second encapsulation layer 150 and the surface of the second encapsulation layer 150 on the bank layer 140 is 0.3 μm or less.

The third encapsulation layer 170 is a water-oxygen barrier layer on the surface, and the material may be selected from inorganic materials, for example, one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium oxide, hafnium oxide, zinc oxide, magnesium oxide, and zirconium oxide. More preferably, the material of the third encapsulation layer 170 is selected from silicon nitride film layers. The water-oxygen barrier layer may be prepared by plasma chemical vapor deposition, atomic layer deposition, ion beam deposition, magnetron sputtering deposition, or the like. More preferably, the method of preparing the water-oxygen barrier layer is plasma chemical vapor deposition.

In one specific example, the height fluctuation of the third encapsulation layer 170 on the surface of the flexible electroluminescent device 10 is less than or equal to 10nm, and the flexible electroluminescent device 10 with a flat surface can be obtained as much as possible by controlling the height of the buffer layer 160 and/or the amount of deposition of the third encapsulation layer 170.

The conventional whole encapsulation layer depends on the form that inorganic encapsulation layers and organic encapsulation layers are alternately laminated so as to have a bendable property while maintaining a barrier property, and the organic encapsulation layer releases stress generated when the inorganic encapsulation layer is bent as much as possible while avoiding defects caused by foreign matters. The flexible electroluminescent device 10 of the above embodiment is different from the conventional whole-surface encapsulation layer, and a discrete encapsulation structure is proposed. The discrete package structure designs a structure of a plurality of package layers for the bank layer 140, and the corresponding light emitting function body 130 and a specific manufacturing process thereof, forming a package type package for the light emitting function body 130. In a portion where the buffer layer 160 is not provided, even if defects or cracks occur in each of the encapsulation layers, intrusion of water and oxygen can be effectively blocked. In addition, the buffer layer coated on the whole surface in the prior art is designed into each buffer layer 160 separately, so that the thickness of the buffer layer 160 can be reduced while the buffer layer 160 protects the luminous functional main body 130 in the dykes 140, and the bending resistance of the whole flexible electroluminescent device 10 can be improved. In addition, the buffer layer 160 is changed to be discrete and filled in the recesses between the bank layers 140, so that the flatness of the flexible electroluminescent device 10 can be ensured as much as possible, and the probability of occurrence of the Mura (Mura) problem can be greatly reduced. Meanwhile, the height of the bank layer 140 of the flexible electroluminescent device 10 in the above example may be set higher, thereby avoiding bad defects such as bridging generated during the printing of the OLED material.

Further, an embodiment of the present invention also provides a method for preparing the flexible electroluminescent device of the above embodiment, which includes the following steps:

Preparing a patterned first packaging layer on a substrate, wherein a light-emitting area is arranged on the substrate, and the first packaging layer is arranged around the light-emitting area on the substrate;

preparing a patterned dyke layer domain outside the light-emitting area on one side of the first packaging layer away from the substrate;

Forming a light emitting function body in a light emitting region on a substrate;

preparing a second encapsulation layer covering the bank layer and the light emitting function body;

Preparing a buffer layer filling the light-emitting area on one side of the second packaging layer in the light-emitting area far away from the light-emitting functional main body;

and preparing a third packaging layer on one side of the buffer layer away from the second packaging layer and one side of the second packaging layer away from the dyke layer.

More specifically, referring to fig. 2, this embodiment is a method for preparing the flexible electroluminescent device 10 of the above embodiment, which includes the following steps.

In step S1, a substrate 110 is provided, and the substrate 110 has a light emitting region thereon.

In one specific example, the thin film transistor 111 is provided in the substrate 110. As one example, the thin film transistor 111 includes a patterned semiconductor layer, a gate insulating layer, a gate conductive layer, an intermediate dielectric layer, a source conductive electrode, a drain conductive electrode, and a planarization layer.

The substrate 110 is provided with a first electrical connection hole filled with a first electrical conductor 112, and the substrate 110 is further provided with a first electrode 131 located in the light emitting region. One end of the first conductor 112 is electrically connected to the drain electrode in the thin film transistor 111, and the other end is electrically connected to the first electrode 131 provided on the substrate 110.

In one specific example, the material of the first electrode 131 may be more preferably a composite film layer of ITO/Ag/ITO. The first electrode 131 may be prepared by a method such as magnetron sputtering, and after preparing the first electrode 131, patterning it so that it is partially or entirely disposed in the light emitting region is further included. The electrode material of the first electrical conductor 112 may be the same as the material of the first electrode 131, whereby the material of the first electrode 131 enters the first electrical connection hole to form the first electrical conductor 112 when the first electrode 131 is prepared by deposition, simplifying the preparation process.

Further, a third electrode 180 is disposed on the substrate 110 and spaced from the first electrode 131, a common electrode 113 and a second electrical connection hole are also disposed in the substrate 110, the second electrical connection hole is filled with a second electrical conductor 114, one end of the second electrical conductor 114 is connected to the common electrode 113, and the other end is connected to the third electrode 180.

In order to simplify the process, the third electrode 180 may be simultaneously prepared when the first electrode 131 is prepared, and then the material of the third electrode 180 is the same as that of the first electrode 131. Further, the second conductor 114 may also be prepared at the same time when the third electrode 180 is prepared, and then the material of the second conductor 114 is the same as that of the third electrode 180.

Specifically, after deposition of an ITO/Ag/ITO laminated film on the surface of the substrate 110, it is patterned to form the first electrode 131 and the third electrode 180.

In step S2, a patterned first encapsulation layer 120 is prepared on the substrate 110, and the first encapsulation layer 120 is disposed around the light emitting region.

Specifically, a film-like material of the first encapsulation layer 120 is formed on the substrate 110, and the first encapsulation layer 120 is patterned such that the first encapsulation layer 120 is disposed around the light emitting region.

Further, the method for preparing the first encapsulation layer 120 is selected from evaporation, magnetron sputtering, plasma chemical vapor deposition, atomic layer deposition or molecular layer deposition. Preferably, a plasma chemical vapor deposition method is selected, and the material of the first encapsulation layer 120 is selected from silicon oxynitride, so that the oxygen content in the deposited silicon oxynitride film can be controlled by controlling the flow rate of each gas raw material during deposition, so that the hydrophilicity of the first encapsulation layer 120 can be adjusted. If the hydrophobicity of the first encapsulation layer 120 is too high, the ink of each layer of the light emitting function body of the subsequent printing may not flow uniformly, thereby reducing the uniformity of the light emitting function body film, affecting the device performance, and even resulting in no OLED material in some pixels.

In one specific example, the formation region of the first encapsulation layer 120 is controlled when the first encapsulation layer 120 is prepared. The method for controlling the formation area of the first encapsulation layer 120 is to deposit a layer of material of the first encapsulation layer 120, and then pattern the first encapsulation layer 120, so that the light-emitting area exposes the surface of the first electrode 131 away from the side of the substrate 110. More specifically, portions of the first electrode 131 are exposed to facilitate subsequent preparation of materials for other layers.

In one specific example, the patterning process of the first encapsulation layer 120 further includes a step of forming a third electrical connection hole for filling the third electrical conductor 121 and exposing the third electrode 180.

In step S3, a patterned bank layer 140 is prepared on a side of the first encapsulation layer 120 away from the board 110 and outside the light emitting region.

The material of the bank layer 140 may be selected from polyimide. The bank layer 140 is prepared by, for example, forming a film layer covering the entire surface of the device by spin coating or slit coating, and patterning the film layer by exposing, developing, curing, etc., to form the bank layer 140.

In one specific example, the patterned bank layer 140 should expose an opening of the third electrical contact hole at a side surface of the first encapsulation layer 120 remote from the substrate 110 so that the third electrical conductor 121 fills and contacts the second electrode 133 disposed later.

Referring to fig. 3, a top view of the semi-finished product prepared in the preparation step is shown. In one specific example, a plurality of light emitting regions are disposed on the substrate 110, and the plurality of light emitting regions are distributed in a plurality of columns, and the bank layer 140 is patterned such that the bank layer 140 is disposed on the first encapsulation layer 120 between the light emitting regions of adjacent columns. Further, the bank layers 140 between the light emitting regions of adjacent columns are continuous in a line shape, and preferably, the bank layers 140 are linear in shape.

The thickness of the linear bank layer 140 may be 1 μm to 6 μm, which is significantly high, and can sufficiently limit the ink in the inkjet printing process. Meanwhile, the bank layers 140 have a certain water-repellent ability, so that ink droplets which then enter the light-emitting region are confined between the bank layers 140, avoiding the disadvantages of bridging and the like.

In step S4, the light emitting function body 130 is formed in the light emitting region.

In one specific example, the light emitting function body 130 includes a first electrode 131, a light emitting function layer 132, and a second electrode 133, and since the first electrode 131 has been formed on the substrate 110 in advance, only the light emitting function layer 132 and the second electrode 133 need be prepared in this step to form the light emitting function body 130.

Specifically, the step of forming the light emitting function body 130 includes preparing a light emitting function layer 132 on a side of the first electrode 131 away from the substrate 110, preparing a second electrode 133 on a side of the light emitting function layer 132 away from the first electrode 131, and extending and filling a material of the second electrode 133 into the third electrical connection hole, wherein the material filled into the third electrical connection hole forms the third electrical conductor 121.

The method for preparing the light emitting functional layer 132 is ink jet printing, specifically, ink containing the material of the light emitting functional layer 132 is sprayed into the light emitting region, and the solvent therein is removed to prepare the light emitting functional layer 132. When the light emitting function layer 132 includes a plurality of layers, such as a light emitting layer, a hole transporting layer, an electron transporting layer, a hole injecting layer, an electron injecting layer, and the like, materials of the respective layers may be sequentially sprayed as appropriate and solvents therein may be removed multiple times or once to prepare the light emitting function layer 132. In one specific example, the height of the light emitting functional layer 132 after the solvent is removed is lower than the height of the first encapsulation layer 120.

After the light emitting functional layer 132 is prepared, the second electrode 133 may be formed in the light emitting region between the bank layers 140 using an inkjet printing or selective atomic layer deposition and patterning deposition plating method. It is understood that the opening of the third electrical connection hole on the side of the first encapsulation layer 120 away from the substrate 110 is also located in the light emitting region, so that the second electrode 133 may directly extend to and fill the third electrical connection hole to form the third electrical conductor 121.

In one specific example, when the light emitting function layer 132 is prepared by inkjet printing, the ink of the light emitting function layer 132 may be simultaneously filled in the third electrical connection hole formed in advance, and thus, after the light emitting function layer 132 is prepared, a step of etching the light emitting function layer 132 with laser light to empty the third electrical connection hole is further included.

In step S5, a second encapsulation layer 150 covering the bank layer 140 and the light emitting function body 130 is prepared.

The method of preparing the second encapsulation layer 150 may be selected from the group consisting of magnetron sputtering, evaporation, plasma enhanced chemical vapor deposition, atomic layer deposition, and molecular layer deposition. In preparing the second encapsulation layer 150, the material of the second encapsulation layer 150 is deposited on the substrate 110 on which the light emitting function body 130 is prepared.

Preferably, the silicon oxynitride film is prepared using a plasma enhanced chemical vapor deposition method.

It will be appreciated that the second encapsulation layer 150 mainly plays a role of water-oxygen barrier, and in addition, has an influence on the light emergent and light emergent, and the preparation of subsequent layers thereon, so as to improve the barrier capability as much as possible, and obtain a more beneficial technical effect, the second encapsulation layer 150 may include multiple sub-encapsulation layers. In preparing the multi-layer sub-package layer, the material of the second package layer 150 is deposited on the substrate on which the light emitting function body 130 is prepared repeatedly.

Further, foreign matters inevitably exist before and after the film plating, and the packaging layer needs to be capable of packaging the foreign matters as much as possible, so that water and oxygen cannot invade the luminous functional main body 130 through defects at the foreign matters, and the luminous functional main body is disabled. However, the second encapsulation layer 150 generally cannot well encapsulate the foreign matter, and thus further provision of the buffer layer 160 is required.

In step S6, a buffer layer 160 filling the light emitting region is prepared at a side of the second encapsulation layer 150 in the light emitting region remote from the light emitting function body 130.

Specifically, the material of the buffer layer 160 may be formed on the second encapsulation layer 150 in the light emitting region using an inkjet printing method to prepare the buffer layer 160. The amount of material of the buffer layer 160 is controlled so that the thickness of the buffer layer 160 is 1 μm to 6 μm.

In one specific example, the buffer layer 160 is prepared to be level with the second encapsulation layer 150 on the bank layer 140 or higher than the second encapsulation layer 150 on the bank layer 140, and the difference in height between the buffer layer 160 and the second encapsulation layer 150 on the bank layer 140 is 0.3 μm or less.

In the conventional whole-surface packaging process, the thickness of the organic buffer layer is usually 8-12 μm. In contrast, the buffer layer 160 in the flexible electroluminescent device 10 of the present embodiment is discrete, and the thickness thereof can be made thinner. While reducing the thickness, the flexible electroluminescent device 10 maintains good bending performance.

In step S7, a third encapsulation layer 170 is prepared on a side of the buffer layer 160 away from the second encapsulation layer 150 and a side of the second encapsulation layer 150 away from the bank layer 140.

The method of preparing the third encapsulation layer 170 may be selected from the group consisting of magnetron sputtering, evaporation, plasma enhanced chemical vapor deposition, atomic layer deposition, and molecular layer deposition. In preparing the third encapsulation layer 170, the material of the third encapsulation layer 170 is deposited on the substrate 110 on which the buffer layer 160 is prepared.

The flexible electroluminescent device 10 of this embodiment can be manufactured by the above manufacturing method.

Further, an embodiment of the present invention also provides a display device, which includes the flexible electroluminescent device described in the above embodiment.

Specifically, the display device is a cell phone, a television, a tablet computer, a display screen, a VR device, an AR device, a computer, or a vehicle-mounted display.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The foregoing examples illustrate only a preferred embodiment of the invention, which is described in more detail and is not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. An electroluminescent device, comprising:

a first encapsulation layer disposed around the light emitting region of the electroluminescent device;

a light-emitting function body disposed within the light-emitting region;

The third packaging layer is arranged on one side, away from the second packaging layer, of the buffer layer;

the light-emitting function main body comprises a first electrode, a second electrode and a light-emitting function layer, wherein the first electrode and the second electrode are oppositely arranged, the light-emitting function layer is arranged between the first electrode and the second electrode, a thin film transistor and a first electric connecting hole are arranged in the substrate, a first electric conductor is filled in the first electric connecting hole, one end of the first electric conductor is electrically connected with a drain electrode in the thin film transistor, the other end of the first electric conductor is electrically connected with the first electrode, a public electrode and a second electric connecting hole are arranged in the substrate, a third electric connecting hole is arranged in the first packaging layer, a second electric conductor is filled in the second electric connecting hole, a third electric conductor is filled in the third electric connecting hole, the second electrode is electrically connected with the public electrode through the second electric conductor and the third electric conductor, and the positive projection of the third electric conductor and the groove is overlapped.

2. The electroluminescent device of claim 1, wherein the light emitting areas are plural and the light emitting areas are distributed in plural rows, and the bank layer is disposed on the first encapsulation layer between the light emitting areas of adjacent rows.

3. The electroluminescent device of claim 1, wherein the second encapsulation layer comprises a plurality of sub-encapsulation layers stacked in a direction from the first encapsulation layer to the third encapsulation layer.

4. An electroluminescent device as claimed in any one of claims 1 to 3 wherein the thickness of the first encapsulation layer is 0.5 μm to 2 μm.

5. An electroluminescent device as claimed in any one of claims 1 to 3, wherein the thickness of the bank layer is 1 μm to 6 μm.

6. An electroluminescent device as claimed in any one of claims 1 to 3 wherein the thickness of the second encapsulation layer is 0.5 μm to 2 μm.

7. An electroluminescent device according to any one of claims 1 to 3, wherein a height difference between a surface of the buffer layer on a side away from the second encapsulation layer and a surface of the second encapsulation layer on a side away from the bank layer is not more than 0.3 μm.

8. An electroluminescent device according to any one of claims 1 to 3, wherein the materials of the first encapsulation layer, the second encapsulation layer and the third encapsulation layer are each independently selected from one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium dioxide, hafnium oxide, zinc oxide, magnesium oxide and zirconium oxide, and/or

The material of the dyke layer is selected from polyimide, and/or

9. A display device characterized by comprising an electroluminescent device according to any one of claims 1 to 8.

10. The display device of claim 9, wherein the display device is a cell phone, a television, a tablet, a display screen, a VR device, an AR device, a computer, or an in-vehicle display.