A display substrate and a flexible OLED screen comprising the same

Abstract

The application provides a display substrate and a flexible OLED screen comprising the same, the display substrate comprising a display area and a non-display area surrounding the display area; the non-display area comprising an encapsulation area and a non-encapsulation area; the non-encapsulation area comprising a bending trace area and a via protection area arranged at both ends of the bending trace area; a first dam being arranged at a near-encapsulation-area end of the non-encapsulation area, a second dam being arranged at a far-encapsulation-area end of the non-encapsulation area; and an organic coating layer being arranged between the first dam and the second dam. The display substrate realizes effective protection of the circuit in the substrate by designing a dam structure in the non-encapsulation area and introducing an organic coating layer, thereby slowing down the invasion of water and oxygen, improving the yield and reliability of the OLED product, and without the need to increase additional processes in the preparation process, thereby significantly improving the encapsulation reliability of the flexible OLED device.

Description

Technical Field

[0001] This invention belongs to the field of organic display technology, specifically relating to a display substrate and a flexible OLED screen containing the substrate. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have the characteristics of self-illumination, wide viewing angle, high brightness, high contrast, flexibility and low power consumption. In recent years, they have received widespread attention from the industry and scientific community and have become the most promising new generation of display technology. They can be made into low-cost light-emitting devices that are compatible with a variety of existing standards and technologies, and have been widely used in flat panel displays, flexible displays, solid-state lighting and automotive displays.

[0003] With the continuous development of display technology, the size and weight of display panels have become important evaluation indicators in their applications. People desire display panels with the smallest possible bezels and the largest possible screen-to-body ratio to make electronic products more aesthetically pleasing, with larger and thinner display areas. Currently, the commonly used narrow bezel technology is OLB bending technology, which involves bending the non-display area of ​​the substrate in the flexible display panel away from the display panel. This involves overlapping the less flexible film layer vias with the more flexible metal layer, and clearing the inorganic film layer in the bending area, thereby reducing the size of the bezel area of ​​the flexible display panel.

[0004] CN105826350A discloses a display device comprising a flexible substrate and an insulating layer on the flexible substrate. The flexible substrate includes a curved region bent in one direction and a plurality of opening patterns spaced apart from each other at the curved region. The display device also includes a wave-shaped line extending through the plurality of opening patterns and bending and extending along the surface of the insulating layer and the bottom of the plurality of opening patterns. The display device, through the design of the curved region in the flexible substrate, can suppress stress damage to the wiring and insulating layer corresponding to the curved portion; however, the planarization treatment above the metal layer of the curved region results in weak encapsulation capabilities, allowing moisture and oxygen from the external environment to intrude along the curved region, affecting the light-emitting performance of the light-emitting device.

[0005] CN107393931A discloses a display device with a curved region. The display device includes a substrate, a first wiring unit, and a second wiring unit. The substrate includes a curved region located between a first region and a second region. Multiple first wirings of the first wiring unit extend sequentially above the first region, the curved region, and the second region, with the first central axis of each first wiring being separated from each other by a first pitch in the curved region. Multiple second wirings of the second wiring unit extend sequentially above the first region, the curved region, and the second region, with the second central axis of each second wiring being separated from each other by a second pitch greater than the first pitch in the curved region. This display device increases the visibility of the display device from various angles and reduces the area of ​​non-display areas by patterning the metal traces in the curved region. However, the encapsulation capability at the edge of the curved region is weak, and the metal layer is easily corroded by water and oxygen intrusion, leading to encapsulation failure and poor bright lines.

[0006] CN107437555A discloses a display substrate and a display device, including a display device located within an encapsulation area of ​​the display substrate, signal lines extending from the encapsulation area to a non-encapsulation area, and a thin-film encapsulation layer covering the portion of the display device and signal lines located in the encapsulation area. The portion of the signal lines located in the non-encapsulation area has a first edge and a second edge opposite each other in the line width direction, and the first edge has alternating protrusions and depressions facing the second edge. This display panel reduces the probability of defects by adjusting the shape of the signal lines in the non-encapsulation area and by using inkjet printing to prepare an organic thin film in the thin-film encapsulation layer, thereby extending the time for the organic solution to flow to the bonding area of ​​the COF. However, the barrier performance of its non-encapsulation area is weak, causing moisture and oxygen to enter the substrate along the non-encapsulation area, resulting in a degradation of the display substrate performance.

[0007] Therefore, developing a display substrate and its packaging structure to improve the barrier function of the display substrate and avoid the weak packaging capability of the bending structure, the corrosion of the layer structure caused by moisture and oxygen intrusion, and the degradation and failure of display performance are problems that urgently need to be solved in this field. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a display substrate and a flexible OLED screen containing the substrate. By designing a dam structure in the non-encapsulated area and introducing an organic coating layer, effective protection of the circuitry in the substrate is achieved, thereby mitigating water and oxygen intrusion and improving the yield and reliability of OLED products.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a display substrate, the display substrate including a display area and a non-display area surrounding the display area; the non-display area includes an encapsulation area and a non-encapsulation area; the non-encapsulation area includes a bent trace area and via protection areas disposed at both ends of the bent trace area.

[0011] A first dike is provided at the near-encapsulation end of the non-encapsulation area, and a second dike is provided at the far-encapsulation end of the non-encapsulation area; an organic coating layer is provided between the first dike and the second dike.

[0012] The structural schematic diagram of the display substrate provided by this invention is shown below. Figure 1 As shown, it includes a display area A and a non-display area B. A schematic diagram of the non-display area B is shown below. Figure 2 As shown, it includes an encapsulated area B1 and a non-encapsulated area B2, with the encapsulated area B1 located between display A and the non-encapsulated area B2. The non-encapsulated area B2 includes a bent trace area C1 and via protection areas C2 disposed at both ends of the bent trace area C1.

[0013] A first dike 1 is provided at the near-encapsulation end of the unencapsulated area B2, and a second dike 2 is provided at the far-encapsulation end of the unencapsulated area; an organic coating layer 3 is provided between the first dike 1 and the second dike 2.

[0014] The non-encapsulated area of ​​the display substrate of the present invention is provided with a dam structure consisting of a first dam and a second dam, and an organic coating layer is introduced between the dam structures. The introduction of the organic coating layer can effectively protect the circuit, increase the path of water and oxygen intrusion, slow down the corrosion rate of the circuit, and increase the yield and reliability of the product.

[0015] Preferably, the unencapsulated area includes a polyimide substrate, an intermediate layer, a first metal layer, and a first organic layer arranged sequentially.

[0016] Preferably, the middle layer of the bent wiring area is a second organic layer.

[0017] Preferably, the intermediate layer of the via protection area includes a buffer layer, a semiconductor layer, a first insulating layer, a second metal layer, a second insulating layer, a third metal layer, and a third insulating layer arranged sequentially; the third insulating layer is interconnected with the first metal layer.

[0018] Preferably, the buffer layer includes a first buffer layer and a second buffer layer.

[0019] Preferably, the first dike and the second dike each independently include a third organic layer and a fourth organic layer arranged sequentially; the third organic layer is interconnected with the first organic layer.

[0020] Preferably, the width of the fourth organic layer is smaller than the width of the third organic layer.

[0021] Preferably, a first inorganic encapsulation layer is provided on the outer side of the first dike, and the third and fourth organic layers of the first dike are encapsulated on the first organic layer.

[0022] Preferably, a second inorganic encapsulation layer is further provided on the outside of the first inorganic encapsulation layer.

[0023] The structural diagram of the non-encapsulated area B2 is shown below. Figure 3 As shown, the bending trace area C1 includes a polyimide substrate 4-1, a second organic layer, a first metal layer 4-3, and a first organic layer 4-4 arranged sequentially; the via protection area C2 includes a polyimide substrate 4-1, a buffer layer 4-5, a semiconductor layer 4-6, a first insulating layer 4-7, a second metal layer 4-8, a second insulating layer 4-9, a third metal layer 4-10, a third insulating layer 4-11, a first metal layer 4-3, and a first organic layer 4-4 arranged sequentially; the first barrier 1 and the second barrier 2 each independently include a third organic layer 5-1 and a fourth organic layer 5-2 arranged sequentially; a first inorganic encapsulation layer 6 is provided on the outer side of the first barrier 1, and an optional second inorganic encapsulation layer 8 can be provided on the outer side of the first inorganic encapsulation layer 6.

[0024] Preferably, the longitudinal width of the first dike and the second dike is independently 30 to 80 μm, for example 32 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 58 μm, 60 μm, 62 μm, 65 μm, 68 μm, 70 μm, 72 μm, 75 μm or 78 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0025] Preferably, the heights of the first and second dikes are each independently 1 to 8 μm, for example 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, 6.2 μm, 6.5 μm, 6.8 μm, 7 μm, 7.2 μm, 7.5 μm, or 7.8 μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0026] Preferably, the thickness of the organic coating layer is 2 to 15 μm, for example 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 14 μm or 14.5 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range. More preferably, it is 4 to 10 μm.

[0027] Preferably, the material of the organic coating layer is a photocurable encapsulating adhesive.

[0028] As a preferred embodiment of the present invention, the photocurable encapsulant contains antioxidants and materials with strong plasma resistance, which can reduce water and oxygen intrusion and damage during the manufacturing process.

[0029] For example, the photocurable encapsulant is ink material SDI FE-FI001T.

[0030] Preferably, 1 to 18 sub-dikes are provided between the first dike and the second dike, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17, and more preferably 1 to 10.

[0031] Preferably, the structure of each of the sub-dikes is the same as that of the second dike.

[0032] Preferably, the longitudinal width of each sub-dike is independently 30 to 80 μm, for example 32 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 58 μm, 60 μm, 62 μm, 65 μm, 68 μm, 70 μm, 72 μm, 75 μm or 78 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0033] Preferably, the height of each sub-dike is independently 1 to 8 μm, for example 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, 6.2 μm, 6.5 μm, 6.8 μm, 7 μm, 7.2 μm, 7.5 μm or 7.8 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0034] Preferably, a first organic coating layer is provided between adjacent first dikes, sub-dikes and second dikes, and a second organic coating layer is provided between adjacent first organic coating layers.

[0035] For example, four sub-dikes are also provided between the first and second dikes, as shown in the schematic diagram below. Figure 4 As shown, a first organic coating layer 3-1 is provided between adjacent first dikes, four sub-dikes and a second dike; a second organic coating layer 3-2 is provided between adjacent first organic coating layers 3-1.

[0036] Preferably, the thickness of each of the first organic coating layers is independently 2 to 15 μm, for example 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 14 μm or 14.5 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but is further preferably 4 to 10 μm.

[0037] Preferably, the thickness of each of the second organic coating layers is independently 2 to 15 μm, for example 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 14 μm or 14.5 μm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and is further preferably 4 to 10 μm.

[0038] Preferably, the materials of the first organic coating layer and the second organic coating layer are both photocurable encapsulants.

[0039] The first organic coating layer and the second organic coating layer are made of the same material as the organic coating layer, and are used to mitigate water and oxygen intrusion and damage during the manufacturing process.

[0040] Preferably, the encapsulation region includes a polyimide substrate, a buffer layer, a first insulating layer, a second metal layer, a second insulating layer, a third metal layer, a third insulating layer, and a first metal layer arranged sequentially; at least three encapsulation region sub-dikes are provided on the first metal layer; each encapsulation region sub-dike includes a first organic layer, a third organic layer, and a fourth organic layer arranged sequentially, the first organic layer being interconnected with the first metal layer; a first inorganic encapsulation layer is provided on the outer side of each encapsulation region sub-dike, encapsulating the encapsulation region sub-dike on the first metal layer.

[0041] Preferably, an organic encapsulating adhesive layer is further disposed on the outer side of the first inorganic encapsulation layer.

[0042] Preferably, the material of the organic encapsulating adhesive layer is the same as that of the organic coating layer.

[0043] The structural diagram of the encapsulation area B1 is shown below. Figure 5 As shown, the structure includes a polyimide substrate 4-1, a buffer layer 4-5, a first insulating layer 4-7, a second metal layer 4-8, a second insulating layer 4-9, a third metal layer 4-10, a third insulating layer 4-11, and a first metal layer 4-3 arranged sequentially. At least three encapsulation sub-dikes are provided on the first metal layer. Each encapsulation sub-dike includes a first organic layer 4-4, a third organic layer 5-1, and a fourth organic layer 5-2 arranged sequentially. A first inorganic encapsulation layer 6 is provided on the outer side of each encapsulation sub-dike, encapsulating the encapsulation sub-dike on the first metal layer. An organic encapsulating adhesive layer 7 is also provided on the outer side of the first inorganic encapsulation layer 6, the material of which is the same as the organic coating layer of the non-encapsulated area.

[0044] The encapsulated area B1 and the unencapsulated area B2 have the same naming hierarchy, and their materials and preparation methods are the same.

[0045] Preferably, a second inorganic encapsulation layer 8 is provided on the encapsulation area to encapsulate the organic coating layer, the first dam, and the encapsulation area near the encapsulation area end.

[0046] On the other hand, the present invention provides a flexible OLED screen, the flexible OLED screen including the display substrate as described above.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The display substrate provided by this invention improves the structure of the non-encapsulated area in the non-display region. By designing a dam structure and introducing an organic coating layer in the non-encapsulated area, and by patterning the bending area, the resulting stacked structure effectively protects the circuitry in the substrate, thereby mitigating water and oxygen intrusion and improving the yield and reliability of OLED products. The failure time of the display substrate under high temperature and high humidity conditions is 480–550 hours, the terminal area failure-related defect rate is <2%, and no additional processes are required during fabrication, significantly improving the encapsulation reliability of flexible OLED devices. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of the display substrate provided by the present invention;

[0050] Figure 2 This is a schematic diagram of the structure of the non-display area in the display substrate provided by the present invention;

[0051] Figure 3 This is a schematic diagram of the structure of the non-encapsulated area in the non-display area of ​​the display substrate provided by the present invention;

[0052] Figure 4 This is a schematic diagram of the structure of the non-encapsulated area in the non-display area of ​​the display substrate described in Example 2;

[0053] Figure 5 This is a schematic diagram of the structure of the packaging area of ​​the non-display area in the display substrate provided by the present invention;

[0054] Figure 6 This is a schematic diagram of the structure of the non-encapsulated area in the non-display area of ​​the display substrate described in Comparative Example 1;

[0055] Wherein, A-display area, B-non-display area, B1-encapsulation area, B2-non-encapsulation area, C1-bent wiring area, C2-via protection area, 1-first dike, 2-second dike, 3-organic encapsulation layer, 4-1-polyimide substrate, 4-3-first metal layer, 4-4-first organic layer, 4-5-buffer layer, 4-6-semiconductor layer, 4-7-first insulating layer, 4-8-second metal layer, 4-9-second insulating layer, 4-10-third metal layer, 4-11-third insulating layer, 5-1-third organic layer, 5-2-fourth organic layer, 6-first inorganic encapsulation layer, 3-1-first organic encapsulation layer, 3-2-second organic encapsulation layer, 7-organic encapsulating adhesive layer, 8-second inorganic encapsulation layer. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0057] Example 1

[0058] This embodiment provides a display substrate, the structural schematic of which is shown below. Figure 1 As shown, it includes display area A and non-display area B.

[0059] The structural diagram of the non-display area B is shown below. Figure 2 As shown, it includes an encapsulation area B1 and a non-encapsulation area B2; the non-encapsulation area B2 includes a bending trace area C1 and via protection areas C2 disposed at both ends of the bending trace area C1; a first dike 1 (longitudinal width of 55μm and height of 5μm) is disposed near the encapsulation area end of the non-encapsulation area B2, and a second dike 2 (longitudinal width of 55μm and height of 5μm) is disposed far from the encapsulation area end of the non-encapsulation area; an organic coating layer 3 (average thickness of 10μm) is disposed between the first dike 1 and the second dike 2; a second inorganic encapsulation layer 8 is disposed on the encapsulation area, encapsulating the organic coating layer 3, the first dike 1, and the encapsulation area at the near-encapsulation area end.

[0060] The structural diagram of the non-encapsulated area B2 is shown below. Figure 3 As shown, the bending trace area C1 includes a polyimide substrate 4-1, a second organic layer, a first metal layer 4-3, and a first organic layer 4-4 arranged sequentially; the via protection area C2 includes a polyimide substrate 4-1, a buffer layer 4-5, a semiconductor layer 4-6, a first insulating layer 4-7, a second metal layer 4-8, a second insulating layer 4-9, a third metal layer 4-10, a third insulating layer 4-11, a first metal layer 4-3, and a first organic layer 4-4 arranged sequentially; the first barrier 1 and the second barrier 2 each include a third organic layer 5-1 and a fourth organic layer 5-2 arranged sequentially; a first inorganic encapsulation layer 6 is provided on the outer side of the first barrier 1, and a second inorganic encapsulation layer 8 is provided on the outer side of the inorganic encapsulation layer 6.

[0061] The structural diagram of the encapsulation area B1 is shown below. Figure 5 As shown, the enclosure includes a polyimide substrate 4-1, a buffer layer 4-5, a first insulating layer 4-7, a second metal layer 4-8, a second insulating layer 4-9, a third metal layer 4-10, a third insulating layer 4-11, and a first metal layer 4-3 arranged sequentially. At least three encapsulation sub-dikes are provided on the first metal layer. Each encapsulation sub-dike includes a first organic layer 4-4, a third organic layer 5-1, and a fourth organic layer 5-2 arranged sequentially. A first inorganic encapsulation layer 6 is provided on the outer side of each encapsulation sub-dike, encapsulating the encapsulation sub-dike on the first metal layer. An organic encapsulating adhesive layer 7 is provided on the outer side of the first inorganic encapsulation layer 6, and a second inorganic encapsulation layer 8 is provided on the outer side of the organic encapsulating adhesive layer 7.

[0062] The material selection and manufacturing process of the display substrate are shown in Table 1:

[0063] Table 1

[0064]

[0065]

[0066] Example 2

[0067] This embodiment provides a display substrate, which differs from Embodiment 1 only in that the structural schematic diagram of the non-encapsulated area B2 is as shown below. Figure 4 As shown, four sub-dikes are provided between the first dike 1 and the second dike 2; a first organic coating layer 3-1 is provided between adjacent first dikes, four sub-dikes, and second dikes; a second organic coating layer 3-2 is provided between adjacent first organic coating layers 3-1; the material of the first organic coating layer 3-1 and the second organic coating layer 3-2 is both Ink material SDI FE-FI001T. Other layer structures and the materials of each layer are the same as in Example 1.

[0068] Comparative Example 1

[0069] This comparative example provides a display substrate, which differs from Embodiment 1 only in that the structural schematic diagram of the non-encapsulated region B2 is as shown below. Figure 6 As shown, it does not contain the first dike, the second dike, and the organic coating layer; the first metal layer 4-3 in the non-encapsulated area is sequentially provided with the first organic layer 4-4, the third organic layer 5-1, and the fourth organic layer 5-2; the other layer structures and the materials of each layer are the same as in Example 1.

[0070] Performance testing:

[0071] The display substrates in Examples 1, 2, and Comparative Example 1 were compared in terms of product yield and the differences in failure time of different stacked products were characterized in reliability testing (high temperature and high humidity operation). The specific methods are as follows:

[0072] (1) Failure Rate Related to Terminal Area Failures: Related defects mainly include localized pixel defects in the display area of ​​the terminal area (caused by water and oxygen intrusion leading to failure of the light-emitting device) and bright lines appearing when the screen is lit. These defects are detected through visual inspection after the screen is lit. The failure modes corresponding to these defects include cracks in the thin-film encapsulation of the terminal area, corrosion of the metal traces in the terminal area, and cracks in the metal traces in the bending area and bending transition area after bending. These defects are discovered through optical microscopy and further corroborated by scanning electron microscopy combined with focused ion beam analysis. The defect rate is calculated as the ratio of the number of displays with the above defects to the total number of displays put into use.

[0073] (2) High temperature and high humidity operation test failure time: The test conditions are 60℃ and 90% humidity (90% RH). The specific test method is as follows:

[0074] Test conditions

[0075] 240 hours, 60℃, 90% RH; if it passes 240 hours, continue testing by adding 120 hours at a time until the first failure screen appears, and record the failure time.

[0076] Temperature tolerance: ±2℃;

[0077] Humidity tolerance: ±3% RH;

[0078] All samples must be powered on during the testing process;

[0079] Condensation is not allowed on the samples during the testing process;

[0080] Sample quantity: 32pcs

[0081] Test steps:

[0082] 1) Inspect the appearance and function of the sample before testing. For TP, check the electrical performance (capacitance and uniformity testing, short-circuit testing, etc.). Record any appearance, mechanical, or functional defects; if these samples are replaced with new ones, this should also be recorded.

[0083] 2) Place the sample inside the incubator, avoiding placing the sample near the door and inner walls of the incubator;

[0084] 3) All samples were powered on during the test;

[0085] 4) Temperature and humidity increase phase: Within 0.6 hours, the temperature increases from 25℃ to 60℃; maintain 60℃ for 0.5 hours, and then within 0.5 hours, the humidity increases from 50% RH to 90% RH;

[0086] 5) Temperature and humidity maintenance phase: Maintain 60℃ and 90% RH conditions for 240 hours, and after 240 hours, switch to 120 hours / cycle;

[0087] 6) Dehumidification and cooling stage: After 240h / 120h damp heat test, the humidity is reduced from 90% RH to 25% RH within 1 hour; then the temperature is reduced from 60℃ to 25℃ within 0.6h (before starting the cooling, it is necessary to check for functional problems such as screen flickering or distorted display every 24 hours in the temperature chamber. If any problems are found, they should be recorded and reported).

[0088] 7) After the temperature drops to 25℃, open the incubator, take out the sample, and allow it to recover at room temperature for 2 hours;

[0089] 8) After restoring at room temperature for 2 hours, perform appearance and function checks and record the test results.

[0090] Qualification Criteria

[0091] During the high temperature and high humidity test and after returning to normal temperature for 2 hours, the display screen functions normally. The display screen sample should meet the normal performance defined in its specifications; no appearance, mechanical or functional defects are allowed.

[0092] The test results are shown in Table 2.

[0093] Table 2

[0094]

[0095] According to the performance test results in Table 2, compared with Comparative Example 1, Embodiments 1 and 2 of the present invention, by designing a dam structure and introducing an organic coating layer in the non-encapsulated area and performing a graphic design on the bending area, form a stacked structure that can effectively protect the circuits in the substrate, reduce water and oxygen intrusion, and enable the display substrate to achieve a failure time of 480-550 hours in a high temperature and high humidity environment, with a terminal area failure-related defect rate of <2%, and significantly improved yield and packaging reliability.

[0096] The applicant declares that the present invention is illustrated through the above embodiments to provide a display substrate and a flexible OLED screen comprising the same, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A display substrate, characterized in that, The display substrate includes a display area and a non-display area surrounding the display area; the non-display area includes a packaging area and a non-packaging area; the non-packaging area includes a bent trace area and via protection areas disposed at both ends of the bent trace area; A first dike is provided at the near-encapsulation end of the non-encapsulation area, and a second dike is provided at the far-encapsulation end of the non-encapsulation area; an organic coating layer is provided between the first dike and the second dike. The unencapsulated area includes a polyimide substrate, an intermediate layer, a first metal layer, and a first organic layer arranged sequentially. The first and second dikes each independently include a third organic layer and a fourth organic layer arranged sequentially; the third organic layer is connected to the first organic layer.

2. The display substrate according to claim 1, characterized in that, The middle layer of the bent wiring area is the second organic layer.

3. The display substrate according to claim 1, characterized in that, The intermediate layer of the via protection area includes a buffer layer, a semiconductor layer, a first insulating layer, a second metal layer, a second insulating layer, a third metal layer, and a third insulating layer arranged sequentially; the third insulating layer is interconnected with the first metal layer.

4. The display substrate according to claim 3, characterized in that, The buffer layer includes a first buffer layer and a second buffer layer.

5. The display substrate according to claim 1, characterized in that, The width of the fourth organic layer is smaller than the width of the third organic layer.

6. The display substrate according to claim 1, characterized in that, The outer side of the first dike is provided with a first inorganic encapsulation layer, which encapsulates the third and fourth organic layers of the first dike on the first organic layer.

7. The display substrate according to claim 6, characterized in that, A second inorganic encapsulation layer is also provided on the outside of the first inorganic encapsulation layer.

8. The display substrate according to claim 1, characterized in that, The longitudinal width of the first and second dikes is independently 30–80 μm.

9. The display substrate according to claim 1, characterized in that, The heights of the first and second dikes are each 1–8 μm.

10. The display substrate according to claim 1, characterized in that, The thickness of the organic coating layer is 2–15 μm.

11. The display substrate according to claim 10, characterized in that, The thickness of the organic coating layer is 4–10 μm.

12. The display substrate according to claim 1, characterized in that, The organic coating layer is made of a photocurable encapsulating adhesive.

13. The display substrate according to claim 1, characterized in that, There are 1 to 18 sub-dikes between the first and second dikes.

14. The display substrate according to claim 13, characterized in that, There are 1 to 10 sub-dikes between the first and second dikes.

15. The display substrate according to claim 13, characterized in that, The structure of each of the sub-dikes is the same as that of the second dike.

16. The display substrate according to claim 13, characterized in that, Each of the sub-dikes has a longitudinal width of 30–80 μm.

17. The display substrate according to claim 13, characterized in that, The height of each of the sub-dikes is independently 1 to 8 μm.

18. The display substrate according to claim 13, characterized in that, A first organic coating layer is provided between adjacent first dikes, sub-dikes and second dikes, and a second organic coating layer is provided between adjacent first organic coating layers.

19. The display substrate according to claim 18, characterized in that, The thickness of each of the first organic coating layers is independently 2–15 μm.

20. The display substrate according to claim 19, characterized in that, The thickness of each of the first organic coating layers is independently 4–10 μm.

21. The display substrate according to claim 18, characterized in that, The thickness of each of the second organic coating layers is independently 2–15 μm.

22. The display substrate according to claim 21, characterized in that, The thickness of each of the second organic coating layers is independently 4–10 μm.

23. The display substrate according to claim 18, characterized in that, The materials for both the first organic coating layer and the second organic coating layer are photocurable encapsulants.

24. The display substrate according to claim 1, characterized in that, The encapsulation region includes a polyimide substrate, a buffer layer, a first insulating layer, a second metal layer, a second insulating layer, a third metal layer, a third insulating layer, and a first metal layer arranged sequentially. At least three encapsulation sub-dikes are provided on the first metal layer. Each encapsulation sub-dike includes a first organic layer, a third organic layer, and a fourth organic layer arranged sequentially, with the first organic layer connected to the first metal layer. A first inorganic encapsulation layer is provided on the outside of each encapsulation sub-dike, encapsulating the encapsulation sub-dike on the first metal layer.

25. The display substrate according to claim 24, characterized in that, An organic encapsulation layer is also provided on the outside of the first inorganic encapsulation layer.

26. The display substrate according to claim 25, characterized in that, The material of the organic encapsulating adhesive layer is the same as that of the organic coating layer.

27. The display substrate according to claim 1, characterized in that, A second inorganic encapsulation layer is provided on the encapsulation area to encapsulate the organic coating layer, the first dam, and the encapsulation area near the encapsulation area end.

28. A flexible OLED screen, characterized in that, The flexible OLED screen includes a display substrate as described in any one of claims 1 to 27.

Images