Electroluminescent device and display device

Abstract

The present invention discloses an electroluminescent device, which is characterized by comprising: a first encapsulation layer disposed around a light-emitting region; a dam layer disposed on one side of the first encapsulation layer, with grooves formed between the dam layers to expose the light-emitting region; a light-emitting functional body disposed within the light-emitting region; a second encapsulation layer integrally covering the dam layer and the light-emitting functional body; a buffer layer disposed on the side of the second encapsulation layer away from the light-emitting functional body and filled in the grooves; and a third encapsulation layer disposed on the side of the buffer layer away from the second encapsulation layer. In this electroluminescent device, the buffer layer that is coated over the entire surface in the conventional technology is designed as discrete buffer layers, which can reduce the required thickness of the buffer layer. While reducing the thickness of the buffer layer, it can also ensure the overall bend resistance performance of the flexible electroluminescent device.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible device preparation, and in particular to electroluminescent devices, display devices and applications thereof. Background Art

[0002] Traditional flat-panel displays usually have two layers of rigid glass substrates and light-emitting elements and other components located between the rigid glass substrates, and can only display based on a plane. Flexible displays usually replace the rigid glass substrates in traditional displays with flexible substrates and flexible encapsulation layers, and combine improvements in the light-emitting elements and other components therein to achieve flexible or foldable display effects. Such flexible displays can bring richer usage performances and provide more possibilities for the form of electronic devices, and thus have gradually become one of the key research projects of major manufacturers.

[0003] Traditional light-emitting elements are extremely sensitive to water and oxygen and are very likely to fail under the influence of water and oxygen. Therefore, the encapsulation layer needs to have a strong water and oxygen barrier ability, for example, it needs to reach 10 -6 g / cm 2 ·day. Moreover, since the flexible display will face relatively frequent bending operations during actual use, the encapsulation layer in the flexible display will also face frequent bending. On the one hand, in order not to break as much as possible during frequent bending, the internal stress of the encapsulation layer itself should not be too large; on the other hand, frequent bending may also cause local defects in the encapsulation layer, resulting in a reduction in the water and oxygen barrier ability.

[0004] In order to be able to balance both the water and oxygen barrier ability and the anti-bending ability at the same time, in traditional technologies, a structure in which an inorganic water and oxygen barrier layer and an organic buffer layer are alternately laminated is often used as the encapsulation layer. The inorganic water and oxygen barrier layer plays the role of efficiently blocking water and oxygen, and the organic buffer layer plays the role of buffering deformation and minimizing the overall internal stress of the encapsulation layer as much as possible. Limited by the precision of the preparation process, foreign matters or pinhole-like defects often appear locally in the encapsulation layer. The foreign matter or defect will become an intrusion point for water and oxygen and gradually spread, and the deteriorated area in the encapsulation layer will continue to expand and finally evolve into serious quality defects. Therefore, an organic buffer layer is needed to cover the foreign matter and vacuum to provide a flat encapsulation surface for the inorganic water and oxygen barrier layer. The thickness of the organic buffer layer generally needs to reach 10μm - 20μm to achieve effective foreign matter coverage and meet the requirements of the encapsulation yield. However, a relatively thick organic buffer layer also reduces the bending radius and bending tolerance of the flexible display at the same time. For the above reasons, it is often difficult to simultaneously meet the bending performance and the barrier performance of the flexible display. Summary of the Invention

[0005] In view of this, the present invention designs an electroluminescent device with good barrier performance and bending performance, and correspondingly provides a display device.

[0006] According to an embodiment of the present invention, an electroluminescent device includes:

[0007] A first encapsulation layer disposed around a light-emitting region;

[0008] A dam layer disposed on one side of the first encapsulation layer, with grooves formed between the dam layers to expose the light-emitting region;

[0009] A light-emitting functional body disposed within the light-emitting region;

[0010] A second encapsulation layer entirely covering the dam layer and the light-emitting functional body;

[0011] A buffer layer disposed on a side of the second encapsulation layer away from the light-emitting functional body and filling the grooves;

[0012] A third encapsulation layer disposed on a side of the buffer layer away from the second encapsulation layer.

[0013] In one embodiment, there are multiple light-emitting regions, and the multiple light-emitting regions are distributed in multiple columns, and the dam layer is disposed on the first encapsulation layer between the light-emitting regions in adjacent columns.

[0014] In one embodiment, the second encapsulation layer includes multiple sub-encapsulation layers stacked in a direction from the first encapsulation layer to the third encapsulation layer.

[0015] In one embodiment, it further includes a substrate. The first encapsulation layer is disposed on the substrate, the dam layer is disposed on a side of the first encapsulation layer away from the substrate, and the light-emitting functional body includes: a first electrode and a second electrode disposed opposite to each other and a light-emitting functional layer disposed between the first electrode and the second electrode;

[0016] A thin-film transistor and a first electrical connection hole are provided in the substrate, the first electrical connection hole is filled with a first conductor, one end of the first conductor is electrically connected to the drain in the thin-film transistor, and the other end is electrically connected to the first electrode.

[0017] In one embodiment, a common electrode and a second electrical connection hole are provided in the substrate, a third electrical connection hole is provided in the first encapsulation layer, the second electrical connection hole is filled with a second conductor, the third electrical connection hole is filled with a third conductor; the second electrode is electrically connected to the common electrode through the second conductor and the third conductor.

[0018] In one embodiment, the thickness of the first encapsulation layer is 0.5 μm to 2 μm; and / or

[0019] The thickness of the dam layer is 1 μm to 6 μm; and / or

[0020] The thickness of the second encapsulation layer is 0.5 μm to 2 μm.

[0021] In one embodiment, the height difference between the surface of the buffer layer on the side away from the second encapsulation layer and the surface of the second encapsulation layer on the side away from the dam layer is ≤ 0.3 μm.

[0022] In one embodiment, 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 dioxide, zinc oxide, magnesium oxide, and zirconium oxide; and / or

[0023] The material of the dam layer is selected from polyimide; and / or

[0024] The material of the buffer layer is selected from one or more of silicon carbonitride, silicon oxycarbide, fluorinated silicon oxycarbide, fluorinated silicon carbonitride, polydimethylsiloxane, parylene, polypropylene, polystyrene, and polyimide.

[0025] A display device includes the electroluminescent device described in any of the above embodiments.

[0026] In one embodiment, the display device is a mobile phone, a television, a tablet computer, a display screen, a VR device, an AR device, a computer, or a vehicle-mounted display.

[0027] The traditional full-surface encapsulation layer relies on the form of alternating inorganic and organic encapsulation layers to have both barrier properties and bendability while maintaining barrier performance. The organic encapsulation layer releases the stress generated by the inorganic encapsulation layer during bending as much as possible and avoids defects caused by foreign objects.

[0028] The electroluminescent device in the above embodiments is different from the traditional full-surface encapsulation layer and proposes a discrete encapsulation structure. The discrete encapsulation structure designs the structure of the multi-layer encapsulation layer for the structure of the dam layer and corresponding to the light-emitting functional body and its specific manufacturing process, forming a wrapped encapsulation of the light-emitting functional body. In the local area without a buffer layer, even if defects or cracks occur in each encapsulation layer, the intrusion of water and oxygen can be effectively blocked. Moreover, by designing the buffer layer that is integrally coated in the traditional technology into discrete buffer layers, the required thickness of the buffer layer can be reduced. While reducing the thickness of the buffer layer, the overall bend resistance of the flexible electroluminescent device can still be ensured.

[0029] In addition, the buffer layer is changed to a discrete type and filled in the depression between the dam layers, which can ensure the flatness of the flexible electroluminescent device as much as possible and greatly reduce the probability of occurrence of Mura problems. At the same time, the height of the dam layer of the flexible electroluminescent device in the above embodiment can be set relatively high, so as to avoid bad defects such as bridging generated during the printing process of the OLED material. Description of the Drawings

[0030] Figure 1 It is a schematic cross-sectional structure diagram of a flexible electroluminescent device according to an embodiment;

[0031] Figure 2 It is a schematic cross-sectional structure diagram of step S1 in the manufacturing process of the flexible electroluminescent device;

[0032] Figure 3 It is a schematic cross-sectional structure diagram of step S2 in the manufacturing process of the flexible electroluminescent device;

[0033] Figure 4 It is a schematic cross-sectional structure diagram of step S3 in the manufacturing process of the flexible electroluminescent device;

[0034] Figure 5 It is a top view of step S3 in the manufacturing process of the flexible electroluminescent device;

[0035] Figure 6 It is a schematic cross-sectional structure diagram of step S4 in the manufacturing process of the flexible electroluminescent device;

[0036] Figure 7 It is a schematic cross-sectional structure diagram of step S5 in the manufacturing process of the flexible electroluminescent device;

[0037] Figure 8 It is a schematic cross-sectional structure diagram of step S6 in the manufacturing process of the flexible electroluminescent device;

[0038] Figure 9 It is a schematic cross-sectional structure diagram of step S7 in the manufacturing process of the flexible electroluminescent device.

[0039] Among them, the reference numerals of each drawing and their meanings are as follows:

[0040] 110: Substrate; 111: Thin-film transistor; 112: First conductor; 113: Common electrode; 114: Second conductor; 120: First encapsulation layer; 131: First electrode; 132: Light-emitting functional layer; 133: Second electrode; 140: Dam layer; 150: Second encapsulation layer; 160: Buffer layer; 170: Third encapsulation layer; 180: Third electrode. Detailed Embodiments

[0041] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. The term "plurality" used herein means a combination of two or more items. If not explicitly stated or commonly understood by those skilled in the art, concepts such as ratios or concentrations in this application shall be considered as mass ratios or mass concentrations.

[0043] In traditional flexible light-emitting devices, the barrier layer usually adopts a way of alternately laminating organic / inorganic film layers. However, such barrier layers are difficult to balance the bending resistance and barrier performance of flexible devices. In order to improve the barrier performance of the flexible light-emitting device as much as possible while ensuring its bending resistance, an embodiment of the present invention provides a flexible electroluminescent device integrating a barrier layer, which at least includes:

[0044] A first encapsulation layer, which is disposed around the light-emitting area;

[0045] A dam layer, which is disposed on one side of the first encapsulation layer. Grooves are formed between the dam layers to expose the light-emitting area;

[0046] A light-emitting functional body, which is disposed within the light-emitting area;

[0047] A second encapsulation layer, which entirely covers the dam layer and the light-emitting functional body;

[0048] A buffer layer, which is disposed on the side of the second encapsulation layer away from the light-emitting functional body and fills the grooves;

[0049] A third encapsulation layer, which is disposed on the side of the buffer layer away from the second encapsulation layer.

[0050] In one specific example, the first encapsulation layer is disposed on a substrate, and the dam layer is disposed on the side of the first encapsulation layer away from the substrate.

[0051] Specifically, for the convenience of understanding and implementing this embodiment, please refer to Figure 1, a flexible electroluminescent device 10, which includes: a substrate 110, a first encapsulation layer 120, a light-emitting functional body 130, a dam layer 140, a second encapsulation layer 150, a buffer layer 160 and a third encapsulation layer 170.

[0052] Specifically, a patterned first encapsulation layer 120 is provided on the substrate 110. The first encapsulation layer 120 defines a light-emitting area for arranging the light-emitting functional body 130. The light-emitting functional body 130 is disposed on the substrate 110 and within the light-emitting area defined by the first encapsulation layer 120.

[0053] A dam layer 140 is provided on a surface of the first encapsulation layer 120 away from the substrate 110. Grooves are formed between the dam layers 140 to expose the light-emitting area.

[0054] The second encapsulation layer 150 entirely covers the dam layer 140 and the light-emitting functional body 130. Specifically, the second encapsulation layer 150 covers the surface of the dam layer 140 that is not in contact with the first encapsulation layer 120 and extends to cover the surface of the light-emitting functional body 130 away from the substrate 110. Further, the second encapsulation layer 150 covers the entire surface of the substrate 110 having the first encapsulation layer 120, the dam layer 140 and the light-emitting functional body 130.

[0055] The light-emitting functional body 130 is formed within the light-emitting area defined by the first encapsulation layer 120, and the dam layer 140 is disposed on the first encapsulation layer 120. Since grooves are formed between the dam layers 140, the second encapsulation layer 150 covering the light-emitting functional body 130 is lower than the second encapsulation layer 150 covering the dam layer 140, and there are grooves between the second encapsulation layers 150 covering adjacent dam layers 140. Therefore, a buffer layer 160 for filling the grooves is further provided on a surface of the second encapsulation layer 150 away from the light-emitting functional body 130.

[0056] The third encapsulation layer 170 is disposed on a surface of the buffer layer 160 away from the second encapsulation layer 150. Further, in one specific example, when no buffer layer 160 is provided on a surface of the second encapsulation layer 150 away from the dam layer 140, the third encapsulation layer 170 is also disposed on the surface of the second encapsulation layer 150 away from the dam layer 140.

[0057] In one specific example, the light-emitting functional body 130 includes: a first electrode 131, a light-emitting functional layer 132 and a second electrode 133 which are sequentially stacked. Among them, the first electrode 131 is disposed on the substrate 110 and has a portion within the light-emitting area.

[0058] 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 the upper and lower electrodes for driving the movement of the liquid crystal. Also, in one specific example, the light-emitting functional layer 132 may include a light-emitting layer, and the light-emitting layer may be selected from an organic light-emitting layer and a quantum dot light-emitting layer. In this case, the first electrode 131 and the second electrode 133 respectively function to inject holes and electrons.

[0059] In one specific example, the first electrode 131 is an anode and is used to connect to the positive pole of an external power supply.

[0060] In one specific example, the first electrode 131 may be formed of a film layer formed of one of a metal oxide conductive material, an organic conductive material, a conductive metal, and its alloy, or a multilayer film layer structure formed of a plurality of them. The metal oxide conductive material may be selected from ITO (indium tin oxide) and 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, and gold, etc.

[0061] Furthermore, if the light-emitting functional layer 132 is a top-emission structure, that is, light is emitted from the light-emitting region, the first electrode 131 may be an ITO / Ag / ITO stacked structure, where the Ag coating layer acts as a reflective layer to reflect the light emitted by the light-emitting functional layer 132 towards the light-emitting region. The ITO functions to match the work function of the hole injection and transport layers in the light-emitting functional layer 132, enabling holes to be better injected into the light-emitting functional layer 132, which is beneficial to improving the overall efficiency of the light-emitting functional body.

[0062] In one specific example, the second electrode 133 is a cathode. The function of the cathode is similar to that of the anode, playing a role in electrical connection, and electrons are injected into the light-emitting functional layer 132 through the cathode. The second electrode 133 may also be formed of a film layer formed of one of a metal oxide conductive material, an organic conductive material, a conductive metal, and its alloy, or a multilayer film layer structure formed of a plurality of them. The metal oxide conductive material may be selected from ITO (indium tin oxide) and 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, and gold, etc. Furthermore, corresponding to the light-emitting functional layer 132 being a top-emission structure, the second electrode 133 has high transparency, high conductivity, and relatively high stability within its film thickness range.

[0063] In one specific example, the light-emitting functional layer 132 further includes 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.

[0064] In one specific example, the light-emitting functional layer 132 further includes an electron functional layer disposed between the cathode and the light-emitting layer, and the electron functional layer includes at least one of an electron injection layer and an electron transport layer.

[0065] In one specific example, a thin-film transistor 111 and a first electrical contact hole are further provided in the substrate 110. The first electrical contact hole is filled with a first conductor 112. One end of the first conductor 112 is electrically connected to the drain 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 in the thin-film transistor 111 through the first conductor 112. Since the first conductor 112 is disposed inside the substrate 110, the first electrode 131 does not need to be connected to the thin-film transistor through an external lead. Therefore, no additional lead path needs to be formed in the first encapsulation layer 120, which not only saves the manufacturing process but also maintains the integrity of the first encapsulation layer 120.

[0066] In one specific example, a common electrode 113 and a second electrical contact hole are further provided in the substrate 110, and a third electrical contact hole is provided in the first encapsulation layer 120. The second electrical contact hole is filled with a second conductor 114, and the third electrical contact hole is filled with a third conductor 121; the second electrode 133 is electrically connected to the common electrode 113 through the second conductor 114 and the third conductor 121. The common electrode 113 is also disposed inside the substrate 110, and the second electrode 133 is connected to the common electrode 113 through the second conductor 114 and the third conductor 121 inside the device respectively, without forming an additional lead path, which can maintain the integrity of the first encapsulation layer 120 and / or the second encapsulation layer 150.

[0067] In one specific example, a third electrode 180 that contacts the second conductor 114 and the third conductor 121 and is spaced apart from the first electrode 131 is further provided on the substrate 110. The third electrode 180 can serve as a contact point for the second conductor 114 and the third conductor 121, electrically connecting the second conductor 114 and the third conductor 121. Generally, the film-forming region of the second electrode 133 is a whole-surface coating of the display region, and the connection leads thereof to the conductive lines of the thin-film transistor 111 array will be provided outside the display region and connected to the TFT lines through a large-area cathode lap region (including vias and exposed electrode structures), and finally form a loop to light up the light-emitting functional layer 132. In this case, it is necessary to open a channel for the leads in the first encapsulation layer 120 and / or the second encapsulation layer 150, which is equivalent to reserving defective holes, and will cause the flexible electroluminescent device 10 of this embodiment to be unable to achieve a perfect encapsulation. However, the second conductor 114, the third conductor 121, and the common electrode 113 are all provided inside the device. With the help of the second conductor 114 and the third conductor 121, the second electrode 133 can be directly connected to the common electrode 113 through the inside of the device, thus effectively avoiding opening holes communicating with the outside inside the device.

[0068] In one specific example, the first encapsulation layer 120 is a water and oxygen barrier layer, which plays a role in water and oxygen barrier. Materials with too strong hydrophobicity should be avoided for the water and oxygen barrier layer, because the first encapsulation layer 120 with too strong hydrophobicity may prevent the ink from flowing in the light-emitting region, resulting in the ink being unable to flow evenly in the light-emitting region and thus unable to fill the gaps between the first encapsulation layers 120 evenly, leading to the defect of uneven light emission. Specifically, the material of the water and oxygen barrier layer can be selected from inorganic materials. For example, it can be one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium dioxide, hafnium dioxide, zinc oxide, magnesium oxide, and zirconium oxide. More preferably, the material of the water and oxygen barrier layer is selected from silicon oxynitride film layers. The number of oxygen atoms in the silicon oxynitride material can be adjusted, and thus the hydrophilicity and hydrophobicity of the water and oxygen barrier layer can be adjusted. The method for preparing the water and oxygen barrier layer can be plasma chemical vapor deposition, atomic layer deposition, ion beam deposition, or magnetron sputtering deposition, etc. More preferably, the method for preparing the water and oxygen barrier layer is plasma chemical vapor deposition.

[0069] In one specific example, 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 functional layer 132 in the light-emitting functional body 130.

[0070] The dam layer 140 is configured to serve as a partition wall between different light-emitting functional bodies 130. After the dam layer 140 is provided, when preparing each film layer of the light-emitting functional body 130 by a solution method such as inkjet printing, the ejected ink can be confined within the light-emitting region and the light-emitting region by the relatively high dam layer 140.

[0071] In one specific example, a plurality of light-emitting regions are provided on the substrate 110, and the plurality of light-emitting regions are distributed in multiple columns. The dam layer 140 is provided on the first encapsulation layer 120 between the light-emitting regions of adjacent columns. The flexible electroluminescent device 10 includes light-emitting functional bodies 130 distributed in multiple columns. The dam layer 140 is only provided between the light-emitting regions of adjacent columns. Further, the dam layer 140 between the light-emitting regions of adjacent columns is a continuous dam layer 140, that is, a linear dam layer 140. The linear dam layer 140 actually defines a plurality of pixel light-emitting units in one column. The inkjet method can be changed from individual inkjet printing to linear printing, which can reduce the accuracy of the inkjet device in the linear printing direction, reduce the accuracy requirements for the device, and thus reduce the cost.

[0072] In one specific example, the material of the dam layer 140 can be selected from organic materials, such as polyimide. In actual preparation, methods such as spin coating, exposure, and development can be used to achieve the coating and patterning of polyimide.

[0073] On the other hand, in the traditional technology, for the encapsulation layer that needs to be provided on the surface of the flexible device, it is required that the height of the dam layer be as low as possible. This is because the higher the height, the more likely the encapsulation layer is to have a low film thickness at the side walls and corners of the dam layer, and in severe cases, peeling will directly occur, resulting in obvious defects and causing encapsulation failure. However, in the flexible electroluminescent device 10 provided in this embodiment, due to the adoption of a separated encapsulation method, the dam layer 140 can be set higher to prevent the bridging phenomenon between adjacent light-emitting functional bodies 130 caused by ink overflow during printing. This is because a buffer layer 160 is also correspondingly provided in the flexible electroluminescent device 10 of this embodiment. Specifically, after the preparation of the second encapsulation layer 150 is completed, the buffer layer 160 will substantially fill the light-emitting regions between the dam layers 140, which can not only buffer the stress of each encapsulation layer, cover the foreign object defects on the second encapsulation layer 150, but also flatten the surface of the device, enabling the uppermost third encapsulation layer 170 to be deposited on a relatively flat plane, effectively improving the reliability of the encapsulation.

[0074] In one specific example, the thickness of the dam layer is 1 μm to 6 μm. Further, the thickness of the dam layer is 3 μm to 6 μm.

[0075] The second encapsulation layer 150 is a water and oxygen barrier layer. Specifically, the material of the second encapsulation layer 150 can be selected from inorganic materials. For example, it can be one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium dioxide, hafnium dioxide, zinc oxide, magnesium oxide, and zirconium oxide. More preferably, the material of the second encapsulation layer 150 is selected from silicon oxynitride film layers. The method for preparing the water and oxygen barrier layer can be plasma chemical vapor deposition, atomic layer deposition, ion beam deposition, or magnetron sputtering deposition, etc. More preferably, the method for preparing the water and oxygen barrier layer is plasma chemical vapor deposition.

[0076] The second encapsulation layer 150 mainly functions to isolate water and oxygen. At the same time, since the second barrier layer 150 covers the light-emitting functional body 130, its thickness should generally be set relatively thin to have a high visible light transmittance. In one specific example, the thickness of the second encapsulation layer 150 is 0.5 μm to 2 μm. Further, the thickness of the second encapsulation layer 150 is 0.5 μm to 1 μm.

[0077] Since the second encapsulation layer 150 covers both the dam layer 140 and the light-emitting functional body 130, and there are obvious height differences between the dam layer 140 and the light-emitting functional body 130, this water and oxygen barrier layer generally has a large internal stress and is not easy to completely cover the foreign objects on the encapsulation surface. There are easily phenomena such as thinner film thickness and fracture at the tips of foreign objects and the bottoms of steps with a negative slope angle. Especially when applied in flexible displays, the encapsulation film is likely to break, peel off, or crack at the places with foreign objects, resulting in encapsulation failure. Therefore, a buffer layer 160 and a third encapsulation layer 170 are further provided in this embodiment.

[0078] The buffer layer 160 is selected from film layer materials with soft texture and small internal stress to make the device surface as flat as possible. And the buffer layer 160 should also have a high light transmittance at the same time. Its material can be selected from inorganic materials with properties close to organic substances, such as: one or more of silicon carbonitride, silicon oxycarbide, fluorinated silicon oxycarbide, and fluorinated silicon carbonitride; or, its material can also be selected from polymer materials, such as: one or more of polydimethylsiloxane, parylene, polypropylene, polystyrene, and polyimide.

[0079] The main function of the buffer layer 160 is to buffer the stress of the film layers above and below it, so that the overall device can have better reliability and bending resistance. Moreover, the buffer layer 160 can also coat the impurity particles that may adhere during the encapsulation process, making the particle edges and corners more rounded and not easily forming channels for water and oxygen permeation, having a certain water and oxygen barrier performance. Its preparation method can be selective coating techniques such as inkjet printing, nanoimprinting, or coating techniques. More preferably, the buffer layer 160 is prepared by inkjet printing. Using the inkjet printing method, ink is dropped at the space between the dams 170, and the thickness of the formed film layer is controlled to be equivalent to the height of the dam layer.

[0080] In one specific example, the buffer layer 160 can extend to cover the surface of the second encapsulation layer 150 on the dam layer 140.

[0081] In one specific example, the thickness of the buffer layer 160 should be set in coordination with the thickness of the dam layer 140, and the surface of the side of the buffer layer 160 away from the second encapsulation layer 150 should be flush with or slightly higher than the surface of the second encapsulation layer 150 on the dam layer 140. Specifically, the height difference between the surface of the side of the buffer layer 160 away from the second encapsulation layer 150 and the surface of the second encapsulation layer 150 on the dam layer 140 is ≤ 0.3 μm.

[0082] The third encapsulation layer 170 is a water and oxygen barrier layer on the surface, and the material can be selected from inorganic materials. For example, it can be one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, titanium dioxide, hafnium dioxide, 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 method for preparing the water and oxygen barrier layer can be plasma enhanced chemical vapor deposition, atomic layer deposition, ion beam deposition, or magnetron sputtering deposition, etc. More preferably, the method for preparing the water and oxygen barrier layer is plasma enhanced chemical vapor deposition.

[0083] In one specific example, the height fluctuation of the third encapsulation layer 170 on the surface of the flexible electroluminescent device 10 is ≤ 10 nm, and a 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 deposition amount of the third encapsulation layer 170.

[0084] Traditional full-surface encapsulation layers rely on the alternating stacking of inorganic and organic encapsulation layers to combine bendability while maintaining barrier performance. The organic encapsulation layer releases the stress generated by the inorganic encapsulation layer during bending as much as possible and avoids defects caused by foreign objects. The flexible electroluminescent device 10 in the above embodiments is different from traditional full-surface encapsulation layers and proposes a discrete encapsulation structure. The discrete encapsulation structure designs the structure of multiple encapsulation layers for the dam layer 140 and corresponding to the light-emitting functional body 130 and its specific preparation process, forming a wrapped encapsulation of the light-emitting functional body 130. In the local area without the buffer layer 160, even if defects or cracks occur in each encapsulation layer, the intrusion of water and oxygen can be effectively blocked. Moreover, the buffer layer that is coated on the entire surface in the traditional technology is designed as discrete buffer layers 160. While ensuring the protection of the light-emitting functional body 130 in the dam layer 140 by the buffer layer 160, the required thickness of the buffer layer 160 can be reduced, increasing the overall bend resistance of the flexible electroluminescent device 10. In addition, the buffer layer 160 is changed to a discrete type and filled in the depressions between the dam layers 140, which can ensure the flatness of the flexible electroluminescent device 10 as much as possible and greatly reduce the probability of Mura problems. At the same time, the height of the dam layer 140 of the flexible electroluminescent device 10 in the above factual examples can be set relatively high, thereby avoiding defective problems such as bridging generated during the printing process of the OLED material.

[0085] Further, an embodiment of the present invention also provides a preparation method for the flexible electroluminescent device of the above embodiment, which includes the following steps:

[0086] Prepare a patterned first encapsulation layer on the substrate. There is a light-emitting area on the substrate, and the first encapsulation layer is arranged around the light-emitting area on the substrate;

[0087] Prepare a patterned dam layer area on the side of the first encapsulation layer away from the substrate and outside the light-emitting area;

[0088] Form a light-emitting functional body in the light-emitting area on the substrate;

[0089] Prepare a second encapsulation layer covering the dam layer and the light-emitting functional body;

[0090] Prepare a buffer layer filling the light-emitting area on the side of the second encapsulation layer away from the light-emitting functional body in the light-emitting area;

[0091] Prepare a third encapsulation layer on the side of the buffer layer away from the second encapsulation layer and on the side of the second encapsulation layer away from the dam layer.

[0092] More specifically, please refer to Figure 2 , this embodiment is a preparation method for the flexible electroluminescent device 10 of the above embodiment, which includes the following steps.

[0093] Step S1: Provide a substrate 110 with a light-emitting region thereon.

[0094] In one specific example, thin-film transistors 111 are disposed in the substrate 110. As an 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.

[0095] A first electrical contact hole is provided in the substrate 110, and a first conductor 112 is filled in the first electrical contact hole. A first electrode 131 located in the light-emitting region is further provided on the substrate 110. One end of the first conductor 112 is electrically connected to the drain in the thin-film transistor 111, and the other end is electrically connected to the first electrode 131 provided on the substrate 110.

[0096] In one specific example, the material of the first electrode 131 is preferably a composite film layer of ITO / Ag / ITO. The first electrode 131 can be prepared by, for example, magnetron sputtering. After preparing the first electrode 131, it further includes patterning it so that part or all of it is disposed in the light-emitting region. The electrode material of the first conductor 112 can be the same as that of the first electrode 131. Thus, when depositing and preparing the first electrode 131, the material of the first electrode 131 enters the first electrical contact hole to form the first conductor 112, simplifying the manufacturing process.

[0097] Further, a third electrode 180 spaced apart from the first electrode 131 is further provided on the substrate 110. A common electrode 113 and a second electrical contact hole are further provided in the substrate 110. A second conductor 114 is filled in the second electrical contact hole. One end of the second conductor 114 is connected to the common electrode 113, and the other end is connected to the third electrode 180.

[0098] To simplify the process, the third electrode 180 can be prepared simultaneously when preparing the first electrode 131, and the material of the third electrode 180 is the same as that of the first electrode 131. Further, the second conductor 114 can be prepared simultaneously when preparing the third electrode 180, and the material of the second conductor 114 is the same as that of the third electrode 180.

[0099] Specifically, after depositing an ITO / Ag / ITO stacked film on the surface of the substrate 110, it is patterned to form the first electrode 131 and the third electrode 180.

[0100] Step S2: Prepare a patterned first encapsulation layer 120 on the substrate 110, and the first encapsulation layer 120 is disposed around the light-emitting region.

[0101] Specifically, a material for forming a thin film-like first encapsulation layer 120 is formed on the substrate 110, and the first encapsulation layer 120 is patterned so that the first encapsulation layer 120 is disposed around the light-emitting region.

[0102] Furthermore, the method for preparing the first encapsulation layer 120 is selected from evaporation, magnetron sputtering, plasma-enhanced chemical vapor deposition, atomic layer deposition, or molecular layer deposition. More preferably, the plasma-enhanced chemical vapor deposition method is selected, and the material of the first encapsulation layer 120 is selected from silicon oxynitride. In this way, by controlling the flow rates of the respective gas raw materials during deposition, the oxygen content in the deposited silicon oxynitride thin film can be controlled, so that the hydrophilicity type of the first encapsulation layer 120 is adjustable. If the hydrophobicity of the first encapsulation layer 120 is too high, it may cause the ink for printing each layer of the light-emitting functional body to flow unevenly, thereby reducing the uniformity of the light-emitting functional body thin film, affecting the device performance, and even resulting in no OLED material in some pixels.

[0103] In one specific example, when preparing the first encapsulation layer 120, the formation region of the first encapsulation layer 120 is controlled. The method for controlling the formation region of the first encapsulation layer 120 is to first deposit a layer of the material of the first encapsulation layer 120, and then pattern the first encapsulation layer 120 so that the light-emitting region exposes the surface of the first electrode 131 on the side away from the substrate 110. More specifically, a part of the first electrode 131 is exposed to facilitate the preparation of the materials for the subsequent layers.

[0104] In one specific example, during the patterning process of the first encapsulation layer 120, it further includes the step of forming a third electrical connection hole and exposing the third electrode 180, and the third electrical connection hole is used for filling the third conductor 121.

[0105] Step S3, a patterned dam layer 140 is prepared on the side of the first encapsulation layer 120 away from the substrate 110 and outside the light-emitting region.

[0106] The material of the dam layer 140 can be selected from polyimide. The method for preparing the dam layer 140 is, for example: using spin coating or slot coating to form a film layer covering the entire surface of the device, and then patterning the film layer through steps such as exposure, development, and curing to form the dam layer 140.

[0107] In one specific example, the patterned dam layer 140 should expose the opening of the third electrical connection hole on the surface of the first encapsulation layer 120 on the side away from the substrate 110, so as to facilitate the filling of the third conductor 121 and contact the subsequent second electrode 133.

[0108] Please refer to Figure 3, a top view of the semi-finished product obtained in the preparation step. In one specific example, a plurality of light-emitting regions are provided on the substrate 110, and the plurality of light-emitting regions are distributed in multiple columns. The dam layer 140 is patterned so that the dam layer 140 is disposed on the first encapsulation layer 120 between adjacent columns of light-emitting regions. Further, the dam layer 140 between adjacent columns of light-emitting regions is in the form of a continuous line; more preferably, the dam layer 140 is in a straight line.

[0109] The thickness of the linear dam layer 140 can be 1 μm to 6 μm, which is significantly higher and can sufficiently confine the ink during the inkjet printing process. At the same time, the dam layer 140 has a certain hydrophobic ability, so that the ink droplets entering the light-emitting region later are restricted between the dam layers 140, avoiding disadvantages such as bridging.

[0110] Step S4, forming a light-emitting functional body 130 in the light-emitting region.

[0111] In one specific example, the light-emitting functional body 130 includes a first electrode 131, a light-emitting functional layer 132, and a second electrode 133. Since the first electrode 131 has been previously formed on the substrate 110, only the light-emitting functional layer 132 and the second electrode 133 need to be prepared in this step to form the light-emitting functional body 130.

[0112] Specifically, the steps of forming the light-emitting functional body 130 include: preparing the light-emitting functional layer 132 on the side of the first electrode 131 away from the substrate 110, and preparing the second electrode 133 on the side of the light-emitting functional layer 132 away from the first electrode 131, and extending the material of the second electrode 133 and filling it into the third electrical connection hole. The material filled in the third electrical connection hole forms the third conductor 121.

[0113] The method for preparing the light-emitting functional layer 132 is inkjet printing. Specifically, the 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 functional layer 132 includes multiple layers, such as a light-emitting layer, a hole transport layer, an electron transport layer, a hole injection layer, an electron injection layer, etc., the materials of each layer can be sprayed in sequence according to the specific situation and the solvent can be removed multiple times or once to prepare the light-emitting functional layer 132. In one specific example, the height of the light-emitting functional layer 132 after removing the solvent is lower than the height of the first encapsulation layer 120.

[0114] After the light-emitting functional layer 132 is prepared, a second electrode 133 can be formed in the light-emitting region between the dam layers 140 by means of inkjet printing or selective atomic layer deposition and patterned deposition coating. It can be 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. Therefore, the second electrode 133 can directly extend to the third electrical connection hole and be filled in the third electrical connection hole to form a third conductor 121.

[0115] In one specific example, when the light-emitting functional layer 132 is prepared by inkjet printing, the ink of the light-emitting functional layer 132 may be filled in the pre-formed third electrical connection hole at the same time. Therefore, after the light-emitting functional layer 132 is prepared, it further includes a step of laser-etching the light-emitting functional layer 132 to empty the third electrical connection hole.

[0116] Step S5, prepare a second encapsulation layer 150 covering the dam layer 140 and the light-emitting functional body 130.

[0117] The method for preparing the second encapsulation layer 150 can be selected from magnetron sputtering, evaporation coating, plasma-enhanced chemical vapor deposition, atomic layer deposition or molecular layer deposition. When preparing the second encapsulation layer 150, it is only necessary to deposit the material of the second encapsulation layer 150 on the substrate 110 on which the light-emitting functional body 130 is prepared.

[0118] More preferably, a silicon oxynitride film is prepared by plasma-enhanced chemical vapor deposition.

[0119] It can be understood that the second encapsulation layer 150 mainly plays a role in blocking water and oxygen. In addition, it also affects the light extraction of light and the preparation of subsequent layers thereon. In order to improve the blocking ability as much as possible and obtain more beneficial technical effects, the second encapsulation layer 150 can include multiple sub-encapsulation layers. When preparing the multiple sub-encapsulation layers, it is only necessary to repeatedly deposit the material of the second encapsulation layer 150 on the substrate on which the light-emitting functional body 130 is prepared.

[0120] Furthermore, before and after coating, foreign matters will inevitably exist. The encapsulation layer needs to be able to encapsulate these foreign matters as much as possible to prevent water and oxygen from invading the light-emitting functional body 130 through the defects at these foreign matter locations, resulting in failure. However, the second encapsulation layer 150 usually cannot well wrap and encapsulate the foreign matters. Therefore, a buffer layer 160 needs to be further provided.

[0121] Step S6, prepare a buffer layer 160 filling the light-emitting region on the side of the second encapsulation layer 150 in the light-emitting region away from the light-emitting functional body 130.

[0122] Specifically, an inkjet printing method can be adopted to form the material of the buffer layer 160 on the second encapsulation layer 150 in the light-emitting region to prepare the buffer layer 160. The amount of the material of the buffer layer 160 is controlled so that the thickness of the buffer layer 160 is 1 μm to 6 μm.

[0123] In one specific example, the prepared buffer layer 160 is flush with or higher than the second encapsulation layer 150 on the dam layer 140, and the height difference between the buffer layer 160 and the second encapsulation layer 150 on the dam layer 140 is ≤ 0.3 μm.

[0124] In the traditional full-surface encapsulation process, the thickness of the organic buffer layer is usually as high as 8 μm to 12 μm. In contrast, the buffer layer 160 in the flexible electroluminescent device 10 in this embodiment is discrete, and its thickness can be made thinner. While reducing the thickness, the flexible electroluminescent device 10 also maintains good bending performance.

[0125] Step S7, a third encapsulation layer 170 is prepared on the side of the buffer layer 160 away from the second encapsulation layer 150 and on the side of the second encapsulation layer 150 away from the dam layer 140.

[0126] The method for preparing the third encapsulation layer 170 can be selected from magnetron sputtering, evaporation coating, plasma-enhanced chemical vapor deposition, atomic layer deposition or molecular layer deposition methods. When preparing the third encapsulation layer 170, it is only necessary to deposit the material of the third encapsulation layer 170 on the substrate 110 after the buffer layer 160 is prepared.

[0127] Through the above preparation method, the preparation of the flexible electroluminescent device 10 in this embodiment can be completed.

[0128] Furthermore, an embodiment of the present invention also provides a display device, which includes the flexible electroluminescent device described in the above embodiment.

[0129] Specifically, the display device is a mobile phone, a television, a tablet computer, a display screen, a VR device, an AR device, a computer or a vehicle-mounted display.

[0130] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0131] The above embodiments merely represent a preferred implementation mode of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An electroluminescent device, characterized in that, Comprising: A first encapsulation layer disposed around the light-emitting region of the electroluminescent device; A dam layer disposed on one side of the first encapsulation layer, with grooves formed between the dam layers to expose the light-emitting region; A light-emitting functional body disposed within the light-emitting region; A second encapsulation layer covering the dam layer and the light-emitting functional body as a whole; A buffer layer disposed on the side of the second encapsulation layer away from the light-emitting functional body and filling the grooves; A third encapsulation layer disposed on the side of the buffer layer away from the second encapsulation layer; The electroluminescent device further includes a substrate, the first encapsulation layer is disposed on the substrate, the dam layer is disposed on the side of the first encapsulation layer away from the substrate, and the light-emitting functional body includes: a first electrode and a second electrode disposed opposite to each other and a light-emitting functional layer disposed between the first electrode and the second electrode; A thin-film transistor and a first electrical connection hole are provided in the substrate, the first electrical connection hole is filled with a first conductor, one end of the first conductor is electrically connected to the drain in the thin-film transistor, and the other end is electrically connected to the first electrode. A common electrode and a second electrical connection hole are provided in the substrate, a third electrical connection hole is provided in the first encapsulation layer, the second electrical connection hole is filled with a second conductor, and the third electrical connection hole is filled with a third conductor; the second electrode is electrically connected to the common electrode through the second conductor and the third conductor, and the third conductor and the positive projection of the groove overlap.

2. The electroluminescent device according to claim 1, wherein There are multiple light-emitting regions, and the multiple light-emitting regions are distributed in multiple columns, and the dam layer is disposed on the first encapsulation layer between adjacent columns of the light-emitting regions.

3. The electroluminescent device according to claim 1, characterized in that, The second encapsulation layer includes multiple sub-encapsulation layers stacked in the direction from the first encapsulation layer to the third encapsulation layer.

4. The electroluminescent device according to any one of claims 1 to 3, characterized in that, The thickness of the first encapsulation layer is 0.5 μm to 2 μm.

5. The electroluminescent device according to any one of claims 1 to 3, characterized in that, The thickness of the dam layer is 1 μm to 6 μm.

6. The electroluminescent device according to any one of claims 1 to 3, characterized in that, The thickness of the second encapsulation layer is 0.5 μm to 2 μm.

7. The electroluminescent device according to any one of claims 1 to 3, characterized in that, The height difference between the surface of the buffer layer on the side away from the second encapsulation layer and the surface of the second encapsulation layer on the side away from the dam layer is ≤ 0.3 μm.

8. The electroluminescent device according to any one of claims 1 to 3, characterized in that, 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 dioxide, zinc oxide, magnesium oxide, and zirconium oxide; and / or The material of the dam layer is selected from polyimide; and / or The material of the buffer layer is selected from one or more of carbon silicon nitride, carbon silicon oxide, fluorinated carbon silicon oxide, fluorinated carbon silicon nitride, polydimethylsiloxane, parylene, polypropylene, polystyrene, and polyimide.

9. A display device, characterized in that, Comprising the electroluminescent device according to any one of claims 1 to 8.

10. The display device according to claim 9, wherein The display device is a mobile phone, a television, a tablet computer, a display screen, a VR device, an AR device, a computer, or an in-vehicle display.

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