Display device and method for producing display device

Abstract

Provided is a display device (1) comprising a plurality of light-emitting elements (2R, 2G, 2B). A second electrode (4) is a part of a common electrode (8) shared by light-emitting elements (2R, 2G, 2B). A charge transport layer is a part of a common layer (9). Included are a first region (13) having an end (13a) positioned outside an end (12a) of a display region (12) which is provided with the light-emitting elements (2R, 2G, 2B); a second region (14) provided outside the first region (13) and including a connection portion (17) in which a conductive layer (16) that is a layer the same as or lower than that of a first electrode (3) is connected to the common electrode (8); and a third region (15) provided between the first region (13) and the second region (14). An end of the common layer (9) is positioned outside the display region (12). The third region (15) is provided with a protrusion (18) which is in a layer that is lower than the common layer (9) and due to which the end of the common layer (9) is positioned either further inward than the third region (15) or inside the third region (15).

Description

Display device and method for manufacturing the same

[0001] The present invention relates to a display device in which a charge transport layer of a light-emitting element is uniformly formed over the entire display area by, for example, an inkjet device, and a method for manufacturing the display device.

[0002] In a display device having a display area in which OLED (organic light emitting diode) elements are provided and a frame area surrounding the periphery of the display area, a configuration is disclosed in which first and second banks are provided in the frame area to dam up the ink material by stopping the flow of the ink material used in a sealing layer that seals the OLED elements (Patent Document 1).

[0003] International Publication No. 2020 / 194736 Brochure

[0004] When a uniform film is formed over the entire display area of ​​a display device using an inkjet device, unevenness occurs at the boundaries of the coating area because the film thickness differs from that at the center.

[0005] In order to improve this unevenness, if the boundary of the application area is moved outside the display area so that the film thickness within the display area is uniform, the ink will spread and form a film on the cathode contact located outside the display area immediately after application.

[0006] If the space between the display area and the cathode contact is designed to be large in order to prevent the film from being deposited on the cathode contact, the frame area of ​​the display device will become large.

[0007] Therefore, there is a need for a structure that can suppress the spreading of liquid in the display area during inkjet coating, for example, without widening the area between the display area and the cathode contact.

[0008] A display device according to one aspect of the present disclosure includes a plurality of light-emitting elements each having a first electrode, a second electrode that is a layer above the first electrode, and a light-emitting layer and a charge transport layer that are provided between the first electrode and the second electrode, wherein the second electrode is part of a common electrode formed in common for the plurality of light-emitting elements, and the charge transport layer is part of a common layer formed in common for the plurality of light-emitting elements, and includes a display area in which the plurality of light-emitting elements are provided, and includes a first region having an end located outside the end of the display area in a planar view, and a connection portion electrically connecting the common electrode to a conductive layer that is in the same layer as the first electrode or a layer below the first electrode, a second region provided outside the first region, and a third region provided between the first region and the second region, wherein the end of the common layer is located outside the display area, and the third region is provided with a formation area defining portion that is lower than the common layer and that positions the end of the common layer at least one of inside the third region and within the third region.

[0009] A manufacturing method of a display device according to one aspect of the present disclosure includes steps of forming a plurality of light-emitting elements, including a first step of forming a plurality of first electrodes, a second step of forming one of an emissive layer and a charge-transporting common layer, a third step of forming the other of the emissive layer and the charge-transporting common layer, and a fourth step of forming a second electrode which is a common electrode, and also includes a step of forming a conductive layer outside a display area in which the plurality of light-emitting elements are provided, at or before the first step, and a step of providing a formation area defining portion, before the step of forming the charge-transporting common layer, such that an end of the common layer formed in the step of forming the charge-transporting common layer is positioned at least one of between the display area and the formation area defining portion and on the formation area defining portion.

[0010] According to one aspect of the present disclosure, it is possible to provide a display device that can suppress the spreading of liquid in the display area during, for example, inkjet coating, without widening the area between the display area and the cathode contact.

[0011] 1. A plan view of a display device according to embodiment 1. A cross-sectional view taken along line II-II shown in FIG. 1. A partial plan view of the display device. A cross-sectional view taken along line IV-IV shown in FIG. 3. A cross-sectional view of a display device according to embodiment 2. A partial plan view of the display device. A cross-sectional view taken along line VII-VII shown in FIG. 6. A cross-sectional view of a display device according to embodiment 3. A partial plan view of the display device. A cross-sectional view taken along line X-X shown in FIG. 9.

[0012] (Embodiment 1) Fig. 1 is a plan view of a display device 1 according to embodiment 1. Fig. 2 is a cross-sectional view taken along line II-II shown in Fig. 1. Fig. 3 is a partial plan view of the display device 1. Fig. 4 is a cross-sectional view taken along line IV-IV shown in Fig. 3.

[0013] The display device 1 includes a plurality of light-emitting elements 2R (e.g., light-emitting elements emitting red light), a plurality of light-emitting elements 2G (e.g., light-emitting elements emitting green light), and a plurality of light-emitting elements 2B (e.g., light-emitting elements emitting blue light). Each of the light-emitting elements 2R, 2G, and 2B includes a first electrode 3, a second electrode 4 located above the first electrode 3, and light-emitting layers 5R, 5G, and 5B, a first charge transport layer 10, and a second charge transport layer 11 provided between the first electrode 3 and the second electrode 4. The second electrode 4 is part of a common electrode 8 formed in common for the plurality of light-emitting elements 2R, 2G, and 2B. The first charge transport layer 10 and the second charge transport layer 11 are part of a common layer 9 formed in common for the plurality of light-emitting elements 2R, 2G, and 2B. The display device 1 includes a display area 12 in which the plurality of light-emitting elements 2R, 2G, and 2B are provided. The display device 1 includes a first region 13 having an end 13a located outside an end 12a of the display region 12 in a plan view, a connection portion 17 electrically connecting a common electrode 8 to a conductive layer 16 that is in the same layer as the first electrode 3 or a layer lower than the first electrode 3, a second region 14 located outside the first region 13, and a third region 15 located between the first region 13 and the second region 14. The end of the common layer 9 is located outside the display region 12. The third region 15 is provided with a protrusion 18 (formation region defining portion) that is lower than the common layer 9 and positions the end of the common layer 9 at least one of inside the third region 15 and within the third region 15. In this way, in order to suppress the spreading of the liquid during inkjet coating in the region without widening the region between the display region 12 and the connection portion 17, the protrusion 18 is formed between the display region 12 and the connection portion 17. This prevents the ink from being deposited on the cathode contact during inkjet coating, and allows a uniform film to be deposited within the display area 12 by inkjet coating.

[0014] The end 13a of the first region 13 and the inner end 15a of the third region 15 are in contact with each other. The outer end 15b of the third region 15 and the inner end 14a of the second region 14 are in contact with each other. The protrusion 18 is formed higher than the film thickness of the common layer 9. The end 13a of the first region 13 is formed so as to surround the end 12a of the display region 12. The third region 15 is formed so as to surround the first region 13. The second region 14 is formed so as to surround the third region 15. The protrusion 18 is formed so as to surround the end 13a of the first region 13. The protrusion 18 can be formed, for example, by photolithography using an organic photosensitive material or a material that forms a silicon nitride film.

[0015] The height of the protrusion 18 is preferably 1 μm or more and 3 μm or less. The shortest distance between the inner end 18a of the protrusion 18 and the outer end 18b of the protrusion 18 is preferably 100 μm or more and 300 μm or less, and more preferably 100 μm or more and 200 μm or less. The display device 1 includes a bank 7 that exposes the center of the first electrode 3 and covers the end of the first electrode 3. The protrusion 18 and the bank 7 may be in the same layer and made of the same material. In this way, the protrusion 18 can be fabricated in the same layer as the bank 7 that defines the size of the pixel in the display area 12.

[0016] The shortest distance between the edge 12 a of the display area 12 and the inner edge 14 a of the second area 14 is preferably 0.5 mm or more and 1 mm or less, so that the frame area surrounding the display area 12 can be narrowed.

[0017] The common layer 9 includes at least one of a first charge transport layer 10 formed on the first electrode 3 side of the light-emitting layers 5R, 5G, and 5B and a second charge transport layer 11 formed on the second electrode 4 side of the light-emitting layers 5R, 5G, and 5B. In this embodiment, since the first electrode 3 is an anode and the second electrode 4 is a cathode, the first charge transport layer 10 is preferably at least one of a hole injection layer and a hole transport layer. The second charge transport layer 11 is preferably at least one of an electron injection layer and an electron transport layer. The first charge transport layer 10 may be at least one of an electron injection layer and an electron transport layer, and the second charge transport layer 11 may be at least one of a hole injection layer and a hole transport layer. The first charge transport layer 10 and the second charge transport layer 11 contain ink in which charge-transporting nanoparticles or a charge-transporting resin are dissolved. The light-emitting layer 5 preferably contains quantum dots or an organic light-emitting material. However, the light-emitting layer 5 is not limited to a configuration containing quantum dots.

[0018] In this way, the protrusions 18 are formed so as to be positioned in the following order from the inside of the display device 1: the boundary of the display area 12, the boundary of the inkjet printing area, the protrusions 18, and the connection areas 17. The inkjet film is then formed so that the inkjet film formed after drying does not exceed the protrusions 18. As a result, the film thickness unevenness 21 of the common layer 9 that occurs at the boundary of the inkjet printing area does not exist within the display area 12, and the inkjet liquid does not penetrate and form a film in the cathode contact area of ​​the conductive layer 16. The distance D from the display area 12 to the connection areas 17 is preferably 0.5 mm or more and 1 mm or less.

[0019] The first bank and second bank in Patent Document 1 are provided in the frame region outside the cathode contact, but the protrusions 18 according to this embodiment are not provided in the frame region outside the cathode contact, but are provided inside the cathode contact just outside the display region 12. This allows the protrusions 18 to have the effect of preventing the inkjet-deposited film from spreading when the common layer 9 of the functional material that constitutes the device is deposited by inkjet.

[0020] The "functional material" formed by inkjet printing refers to the charge transport layer common to each color other than the light-emitting layers 5R, 5G, and 5B that constitute the OLED, etc. The charge transport layer includes a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer. The structure of the protrusions 18 and the like outside the display area 12 in this embodiment is effective when these charge transport layers are applied by inkjet printing in a so-called solid manner, that is, when they are applied uniformly over the entire display area 12. It is difficult to achieve the effect with a printing method that applies a charge transport layer separately for each pixel rather than in a solid manner.

[0021] In the present embodiment, if the protrusion 18 is too high, there is a risk of a step being generated when forming the common electrode 8 including the second electrode 4 that serves as the cathode, and therefore it is preferable to limit the height to 1-3 μm.

[0022] The manufacturing method of the display device 1 according to the embodiment includes steps of forming a plurality of light-emitting elements 2R, 2G, and 2B, including a first step of forming a plurality of first electrodes 3, a second step of forming one of the light-emitting layer 5 and the charge-transporting common layer 9, a third step of forming the other of the light-emitting layer 5 and the charge-transporting common layer 9, and a fourth step of forming the second electrode 4, which is the common electrode 8.

[0023] The manufacturing method of the display device 1 further includes, in the first step or prior to the first step, a step of forming a conductive layer 16 outside a display region 12 in which a plurality of light-emitting elements 2R, 2G, and 2B are provided, and a step of providing a protrusion 18 (a formation region defining portion) before the step of forming a charge-transporting common layer 9, such that an end of the common layer 9 formed in the step of forming the charge-transporting common layer 9 is positioned at least one of between the display region 12 and the protrusion 18 (a formation region defining portion) and on the protrusion 18 (a formation region defining portion). In the step of providing the formation region defining portion, it is preferable to provide the protrusion 18 having a thickness higher than the film thickness of the common layer 9. (Embodiment 2) FIG. 5 is a cross-sectional view of a display device 1A according to embodiment 2. FIG. 6 is a partial plan view of the display device 1A. FIG. 7 is a cross-sectional view taken along line VII-VII shown in FIG. 6. Components similar to those described above are designated by the same reference numerals. Detailed descriptions of these components will not be repeated.

[0024] The display device 1A includes a liquid-repellent portion 19 (formation region defining portion) that repels the material forming the common layer 9. The end 13a of the first region 13 is formed to surround the end 12a of the display region 12. The third region 15 is formed to surround the first region 13. The second region 14 is formed to surround the third region 15. The liquid-repellent portion 19 is formed to surround the end 13a of the first region 13. The liquid-repellent portion 19 preferably contains a fluorine-based material or a silicon-based material. In this way, by forming the surface of the region between the display region 12 and the conductive layer 16 into the liquid-repellent portion 19 made of a liquid-repellent material, penetration of liquid from the display region 12 to the conductive layer 16 is suppressed.

[0025] Fluorine-based or silicon-based materials can be used as the material for the liquid-repellent portion 19. The distance D from the display area 12 to the connection portion 17 is preferably 0.5 mm or more and 1 mm or less.

[0026] In this way, the liquid-repellent portion 19 is formed so that the positions of the boundary of the display area 12, the boundary of the printing area, the liquid-repellent portion 19, and the connection portion 17 are in this order from the inside of the display device 1A. Although inkjet printing can be performed on the liquid-repellent portion 19, the printed ink is repelled by the liquid-repellent portion 19 and printed so as to form a film on the display area 12 side. As a result, the unevenness in film thickness that occurs at the boundary of the printing area does not exist within the display area 12, and the liquid does not penetrate and form a film in the cathode contact region of the conductive layer 16.

[0027] According to the second embodiment, unlike the first embodiment, there is no protrusion 18 in the region between the display region 12 and the conductive layer 16, so there is no risk of the common electrode 8 being disconnected.

[0028] The shortest distance between the inner end 19a of the liquid-repellent portion 19 and the outer end 19b of the liquid-repellent portion 19 is preferably 100 μm or more and 300 μm or less. The display device 1A includes a bank 7 that exposes a central portion of the first electrode 3 and covers the end of the first electrode 3. The liquid-repellent portion 19 may be provided in an opening in a layer formed of the same material as the bank 7. In the step of providing the formation region defining portion, it is preferable to provide a liquid-repellent portion 19 that repels the material that forms the common layer 9. (Embodiment 3) FIG. 8 is a cross-sectional view of a display device 1B according to embodiment 3. FIG. 9 is a partial plan view of the display device 1B. FIG. 10 is a cross-sectional view taken along line X-X shown in FIG. 9. Components similar to those described above are designated by the same reference numerals. Detailed descriptions of these components will not be repeated.

[0029] The display device 1B includes a groove 20 in a layer below the common layer 9. In this way, the groove 20 is provided as a recess between the display area 12 and the conductive layer 16. This groove 20 may be formed in advance using an organic photosensitive material or the like before creating the circuit of the display area 12 on the backplane substrate. The groove 20 is formed so that, from the inside of the display device 1B, it is positioned in the following order: the boundary of the display area 12, the boundary of the printing area, the groove 20, and the connection portion 17. As a result, the unevenness in film thickness that occurs at the boundary of the printing area does not exist within the display area 12, and the liquid does not penetrate and form a film in the cathode contact area of ​​the conductive layer 16.

[0030] The end 13a of the first region 13 is formed to surround the end 12a of the display region 12. The third region 15 is formed to surround the first region 13. The second region 14 is formed to surround the third region 15. The groove 20 is formed to surround the end 13a of the first region 13. The display device 1B includes a bank 7 that exposes the center of the first electrode 3 and covers the end of the first electrode 3. The layer below the common layer 9 in which the groove 20 is formed and the bank 7 may be the same layer made of the same material. A plurality of grooves 20 may be formed in the layer below the common layer 9. In the step of providing the formation region defining portion, the groove 20 is preferably formed in the layer below the common layer 9. The width of the groove 20 is preferably 100 μm or more and 500 μm or less. The distance D from the display region 12 to the connection portion 17 is preferably 0.5 mm or more and 1 mm or less.

[0031] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0032] REFERENCE SIGNS LIST 1 display device 2R, 2G, 2B light-emitting element 3 first electrode 4 second electrode 5R, 5G, 5B light-emitting layer 10 first charge transport layer 11 second charge transport layer 12 display region 13 first region 14 second region 15 third region 16 conductive layer 17 connection portion 18 protrusion (formation region defining portion) 19 liquid-repellent portion (formation region defining portion) 20 groove (formation region defining portion)

Claims

1. A display device comprising a plurality of light-emitting elements each comprising a first electrode, a second electrode that is a layer higher than the first electrode, and a light-emitting layer and a charge transport layer that are provided between the first electrode and the second electrode, the second electrode being a part of a common electrode formed in common to the plurality of light-emitting elements, the charge transport layer being a part of a common layer formed in common to the plurality of light-emitting elements, a first region including a display region in which the plurality of light-emitting elements are provided and having an end located outside an end of the display region in a planar view, a second region including a connection portion electrically connecting the common electrode to a conductive layer that is in the same layer as the first electrode or is lower than the first electrode, and being provided outside the first region, and a third region provided between the first region and the second region, an end of the common layer being located outside the display region, and the third region being provided with a formation region defining portion that is a layer lower than the common layer and that positions the end of the common layer at least one of inside the third region and within the third region.

2. The display device according to claim 1, wherein an end of the first region and an inner end of the third region are in contact with each other, and an outer end of the third region and an inner end of the second region are in contact with each other.

3. The display device according to claim 1 or 2, wherein the formation region defining portion is a protrusion formed higher than a film thickness of the common layer.

4. The display device of claim 3, wherein an end of the first region is formed so as to surround an end of the display region, the third region is formed so as to surround the first region, the second region is formed so as to surround the third region, and the protrusion portion is formed so as to surround the end of the first region.

5. The display device according to claim 3 or 4, wherein the height of the protrusion is not less than 1 μm and not more than 3 μm.

6. The display device according to claim 3, wherein the shortest distance between the inner end of the protrusion and the outer end of the protrusion is 100 μm or more and 300 μm or less.

7. A display device according to any one of claims 3 to 6, further comprising a bank exposing a central portion of the first electrode and covering an end portion of the first electrode, the protrusion and the bank being the same layer of the same material.

8. The display device according to claim 1, wherein the formation region defining portion is a liquid-repellent portion that repels a material that forms the common layer.

9. The display device of claim 8, wherein an end of the first region is formed so as to surround an end of the display region, the third region is formed so as to surround the first region, the second region is formed so as to surround the third region, and the liquid-repellent portion is formed so as to surround the end of the first region.

10. The display device according to claim 8 or 9, wherein the liquid repellent portion contains a fluorine-based material or a silicon-based material.

11. The display device according to claim 8, wherein the shortest distance between the inner end of the liquid repellent portion and the outer end of the liquid repellent portion is 100 μm or more and 300 μm or less.

12. A display device as described in any one of claims 8 to 11, comprising a bank exposing a central portion of the first electrode and covering an end portion of the first electrode, the liquid-repellent portion being provided in an opening in a layer formed of the same material as the bank and the same layer.

13. The display device according to claim 1 or 2, wherein the formation region defining portion is a groove in a layer below the common layer.

14. The display device of claim 13, wherein an end of the first region is formed so as to surround an end of the display region, the third region is formed so as to surround the first region, the second region is formed so as to surround the third region, and a groove in a layer lower than the common layer is formed so as to surround the end of the first region.

15. A display device as described in claim 13 or 14, further comprising a bank exposing the center of the first electrode and covering the end of the first electrode, wherein the layer below the common layer in which the groove is formed and the bank are the same layer made of the same material.

16. The display device according to any one of claims 13 to 15, wherein a plurality of the grooves are provided in a layer below the common layer.

17. The display device according to any one of claims 1 to 16, wherein the shortest distance between an edge of the display region and an inner edge of the second region is 0.5 mm or more and 1 mm or less.

18. A display device described in any one of claims 1 to 17, wherein the common layer includes at least one of a first charge transport layer formed on the first electrode side of the light-emitting layer and a second charge transport layer formed on the second electrode side of the light-emitting layer.

19. The display device according to claim 18, wherein the first charge transport layer is at least one of a hole injection layer and a hole transport layer, and the second charge transport layer is at least one of an electron injection layer and an electron transport layer.

20. The display device according to claim 18, wherein the first charge transport layer is at least one of an electron injection layer and an electron transport layer, and the second charge transport layer is at least one of a hole injection layer and a hole transport layer.

21. The display device according to claim 18, wherein the first charge transport layer and the second charge transport layer contain ink in which charge transport nanoparticles or a charge transport resin is dissolved.

22. The display device of claim 1, wherein the light-emitting layer comprises quantum dots or an organic light-emitting material.

23. A method for manufacturing a display device, comprising steps of forming a plurality of light-emitting elements, the steps including a first step of forming a plurality of first electrodes, a second step of forming one of a light-emitting layer and a charge-transporting common layer, a third step of forming the other of the light-emitting layer and the charge-transporting common layer, and a fourth step of forming a second electrode which is a common electrode, the method comprising: forming a conductive layer outside a display area in which the plurality of light-emitting elements are provided, during or prior to the first step; and providing a formation area defining portion, prior to the step of forming the charge-transporting common layer, for positioning an end of the common layer formed in the step of forming the charge-transporting common layer at least one of between the display area and the formation area defining portion and on the formation area defining portion.

24. The method of manufacturing a display device according to claim 23, wherein in the step of providing the formation region defining portion, a protruding portion having a thickness greater than that of the common layer is provided.

25. The method for manufacturing a display device according to claim 23, wherein in the step of providing the formation region defining portion, a liquid-repellent portion that repels the material that forms the common layer is provided.

26. The method of manufacturing a display device according to claim 23, wherein in the step of providing the formation region defining portion, a groove is provided in a layer below the common layer.

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