阅读说明：本技术 显示装置及显示装置的制造方法 (Display device and method for manufacturing display device ) 是由 兼弘昌行 仲西洋平 今林弘毅 于 2019-03-06 设计创作，主要内容包括：一种显示装置,具备显示区域及其周围的边框区域,包括:TFT层；发光元件层,其分别包括第一电极、发光层及第二电极,形成有发光颜色相互不同的多个发光元件；以及密封层,其包括有机膜,密封所述发光元件层,第二电极(25)为所述多个发光元件共用的电极,包括网格状的金属纳米线(NW)。(A display device having a display region and a frame region around the display region includes a TFT layer; a light-emitting element layer including a first electrode, a light-emitting layer, and a second electrode, and having a plurality of light-emitting elements having different emission colors; and a sealing layer including an organic film sealing the light emitting element layer, wherein the second electrode (25) is an electrode common to the plurality of light emitting elements and includes metal Nanowires (NW) in a mesh shape.)

1. A display device including a display area and a frame area around the display area, the display device comprising:

a TFT layer;

a light-emitting element layer including a first electrode, a functional layer, and a second electrode, and having a plurality of light-emitting elements with different emission colors;

a sealing layer which includes an organic film and seals the light emitting element layer,

the second electrode is common to the plurality of light emitting elements and includes an electrode of a metal nanowire in a mesh shape.

2. The display device of claim 1,

a planarization film is contained in the TFT layer,

in the frame region, a trench is formed on the planarization film,

outside the trench, a bank portion defining an end of the organic film is disposed.

3. The display device according to claim 2, wherein the convex portion between the groove and the bank is formed in a frame shape so as to surround the display region in a plan view,

the convex portion defines an end portion of the second electrode.

4. A display device according to claim 3, comprising a photo spacer located between the convex portion and the bank portion in a plan view.

5. The display device according to claim 4, wherein the convex portion is smaller than a film thickness of the photo spacer.

6. The display device according to any one of claims 3 to 5,

the light emitting element layer includes an edge covering film covering an edge of the first electrode,

the convex part and the edge covering film are in the same layer and made of the same material.

7. The display device according to any one of claims 2 to 6,

a conductive film of the same layer and formed of the same material as the first electrode is provided across the trench,

the conductive film and the second electrode are in contact within the trench.

8. The display device according to any one of claims 2 to 7, wherein in the frame region, a main wiring is provided below the planarization film,

in the planarization film, a contact groove for exposing the main wiring is provided on the display region side of the bank portion,

the second electrode is electrically connected to the main wiring.

9. A display device as claimed in claim 2, wherein the banks define ends of the second electrodes.

10. The display device of claim 2, wherein the trench defines an end of the second electrode.

11. The display device according to claim 10, wherein the groove is provided in a frame shape so as to surround the entire circumference of the display region.

12. The display device according to claim 3, wherein a terminal portion including a plurality of terminals is provided in the bezel region,

the groove is provided to surround a part of four sides of the display area along one side of the terminal portion and all of the other three sides,

for a portion along the one side in the end portion of the second electrode, a part is defined by the convex portion, and another part is defined by the groove,

a portion of the end portion of the second electrode along the three sides is defined by the groove.

13. The display device according to any one of claims 1 to 12, wherein a terminal portion including a plurality of terminals is provided in the bezel region,

the length of the metal nanowire is smaller than the distance between adjacent terminals.

14. The display device according to any one of claims 1 to 13, wherein the organic film is formed over the second electrode.

15. The display device according to any one of claims 1 to 14, wherein the light-emitting layer is a quantum dot layer.

16. The display device according to any one of claims 1 to 15, wherein the light-emitting layer is an organic layer.

17. The display device according to any one of claims 1 to 16, wherein a light transmittance of the second electrode is 80% or more.

18. The display device according to any one of claims 1 to 17, wherein the metal nanowires contain at least one of Ag, Au, Al, and Cu.

19. The display device according to any one of claims 1 to 18, wherein the first electrode is an anode, the second electrode is a cathode,

the second electrode includes an electron transport material.

20. The display device according to claim 19, wherein the second electrode is in contact with the light-emitting layer.

21. The display device of claim 19 or 20, wherein the electron transport material is zinc oxide nanoparticles.

22. The display device according to claim 21, wherein a volume ratio of the metal nanowires to the zinc oxide nanoparticles is 1/49 to 1/9.

23. A method of manufacturing a display device, the display device comprising:

a TFT layer;

a light-emitting element layer in which a plurality of light-emitting elements having different emission colors and including a first electrode, a functional layer, and a second electrode are formed; and

a sealing layer which includes an organic film and seals the light emitting element layer,

the manufacturing method of the display device includes:

and a step of forming the second electrode by applying an ink in which the metal nanowires are dispersed in a solvent and removing the solvent.

Technical Field

The invention relates to a display device and a method of manufacturing the display device.

Background

Patent document 1 discloses a top emission type organic EL display device in which a semi-transparent metal thin film of magnesium-silver alloy or the like or a transparent metal oxide thin film of ITO or the like is used as a second electrode (cathode) as an upper electrode.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication "2017-183510 (published 10/5/2017)"

Disclosure of Invention

Problems to be solved by the invention

In the structure of patent document 1, when a semi-transparent metal thin film such as a magnesium-silver alloy is used, the transmittance of light is low, and a cavity effect may occur due to partial light reflection, thereby causing a problem of deterioration in viewing angle characteristics. On the other hand, when a thin film of a light-transmitting metal oxide such as ITO is used, there is a problem that damage to a light-emitting layer or the like occurs during the sputtering deposition, for example, and the light-emitting characteristics are degraded.

Means for solving the problems

A display device according to an embodiment of the present invention includes a display region and a frame region around the display region, and includes a TFT layer; a light-emitting element layer including a first electrode, a functional layer, and a second electrode, and having a plurality of light-emitting elements with different emission colors; and a sealing layer including an organic film sealing the light emitting element layer, the second electrode being an electrode common to the plurality of light emitting elements and including a mesh-like metal nanowire.

Effects of the invention

According to one embodiment of the present invention, a display device in which the viewing angle characteristics can be improved while preventing the light emission characteristics from being degraded can be realized.

Drawings

Fig. 1 (a) is a schematic diagram showing the structure of the display device of the first embodiment, fig. 1(b) is a sectional diagram showing the structure of the display device of the first embodiment, and fig. 1 (c) is a sectional diagram showing the structure of the functional layer.

Fig. 2 (a) is a photograph showing the structure of the second electrode, fig. 2 (b) is a perspective view showing the structure of the second electrode, and fig. 2 (c) is a schematic view showing the length of the metal nanowire.

Fig. 3 is a graph showing the effect of the first embodiment.

Fig. 4(a) and (b) are graphs showing the effect of the 2 nd electrode (metal nanowire electrode) when the light-emitting element has a quantum dot light-emitting layer.

Fig. 5 is a flowchart illustrating a method of manufacturing a display device.

Fig. 6 (a) is a plan view showing the structure of the display device of the first embodiment, and fig. 6 (b) is a sectional view of an edge.

Fig. 7 (a) is a plan view showing a first modification of fig. 6, and fig. 7 (b) is a sectional view of an edge.

Fig. 8(a) is a plan view showing a second modification of fig. 6, and fig. 8 (b) is a sectional view of an edge.

Fig. 9(a) is a plan view showing a third modification of fig. 6, and fig. 9 (b) is a sectional view of an edge.

Fig. 10 (a) is a schematic perspective view showing the structure of the second electrode in the second embodiment, fig. 10 (b) is a schematic cross-sectional view showing the structure of the light-emitting element in the second embodiment, and fig. 10 (c) is a graph showing the effects of the structures of fig. 10 (a) and (b).

Detailed Description

[ first embodiment ]

Hereinafter, "same layer" means a layer formed of the same material in the same process (film forming process), "lower layer" means a layer formed in a process earlier than a comparison object layer, and "upper layer" means a layer formed in a process later than the comparison object layer.

Fig. 1 (a) is a schematic diagram showing the structure of the display device of the first embodiment, fig. 1(b) is a sectional diagram showing the structure of the display device of the first embodiment, and fig. 1 (c) is a sectional diagram showing the structure of the functional layer.

In the display device 2, a barrier layer 3, a TFT layer 4, a top emission type light emitting element layer 5, and a sealant layer 6 are sequentially provided on a substrate 12, and a plurality of subpixels SP are formed in a display region DA. The frame area NA surrounding the display area DA is formed of 4 edges Fa to Fd, and a terminal portion TA for mounting an electronic circuit board (an IC chip, an FPC, or the like) is formed at the edge Fd. The terminal portion TA includes a plurality of terminals TM1, TM 2. A drive circuit (not shown) may be formed at each of the edges Fa to Fd.

The base material 12 may be a glass substrate or a flexible substrate including a resin film such as polyimide. The flexible substrate may be formed of two resin films and an inorganic insulating film interposed therebetween. A film such as PET may be attached to the lower surface of the base material 12. The flexible substrate is used as the base material 12, and the display device 2 having flexibility (flexible) may be formed.

The barrier layer 3 is a layer for preventing foreign substances such as water and oxygen from entering the TFT layer 4 and the light-emitting element layer 5, and may be formed of, for example, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film formed by a CVD method, or a laminated film of these layers.

As shown in fig. 1(b), the TFT (thin film transistor) layer 4 includes a semiconductor layer (including a semiconductor film 15) on the upper layer than the barrier layer 3, an inorganic insulating film 16 (gate insulating film) on the upper layer than the semiconductor layer, a first metal layer (including a gate electrode GE) on the upper layer than the inorganic insulating film 16, an inorganic insulating film 18 on the upper layer than the first metal layer, a second metal layer (including a capacitance electrode CE) on the upper layer than the inorganic insulating film 18, an inorganic insulating film 20 on the upper layer than the second metal layer, a third metal layer (including a data signal line DL) on the upper layer than the inorganic insulating film 20, and a planarization film 21 on the upper layer than the third metal layer.

The semiconductor layer is made of, for example, amorphous silicon, LTPS (low temperature polysilicon), or an oxide semiconductor, and the thin film transistor TR is configured to include the gate electrode GE and the semiconductor film 15.

In the display area DA, a light-emitting element X and a pixel circuit are provided for each sub-pixel SP, and the pixel circuit and a wiring connected thereto are formed in the TFT layer 4. Examples of the wiring lines connected to the pixel circuits include a scanning signal line GL and an emission control line EM formed in a first metal layer, an initialization power line IL formed in a second metal layer, and a data signal line DL and a high-voltage power line PL formed in a third metal layer. The pixel circuit includes a driving transistor which controls a current of the light emitting element, a writing transistor electrically connected to the scanning signal line, a light emission control transistor electrically connected to the light emission control line, and the like.

The first metal layer, the second metal layer, and the third metal layer are formed of, for example, a single-layer film or a multilayer film of a metal containing at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper.

The inorganic insulating films 16, 18, and 20 may be formed of, for example, a silicon oxide (SiOx) film or a silicon nitride (SiNx) film formed by a CVD method, or a stacked film thereof. The planarization film 21 can be made of a coatable organic material such as polyimide or acrylic resin.

The light-emitting element layer 5 includes a first electrode (anode) 22 on the upper layer of the planarization film 21, an insulating edge cover film 23 covering the edge of the first electrode 22, an EL (electroluminescence) layer 24 on the upper layer of the edge cover film 23, and a second electrode 25 on the upper layer of the functional layer 24. The edge cover film 23 is formed by, for example, coating an organic material such as polyimide or acrylic resin and then patterning the coating by photolithography.

In the light-emitting element layer 5, a light-emitting element Xr (red), a light-emitting element Xg (green), and a light-emitting element Xb (blue) having different emission colors are formed, and each light-emitting element includes an island-shaped first electrode 22, a functional layer 24 (including a light-emitting layer), and a second electrode 25. The second electrode 25 is a common electrode of a whole shape common to the plurality of light emitting elements.

The light-emitting element Xr · Xg · Xb may be, for example, an OLED (organic light-emitting diode) including an organic layer as a light-emitting layer, or a QLED (quantum dot light-emitting diode) including a quantum dot layer as a light-emitting layer.

As shown in fig. 1 (c), the functional layer 24 is formed by stacking a hole injection layer 24a, a Hole Transport Layer (HTL)24b, a light-emitting layer 24c, an Electron Transport Layer (ETL)24d, and an electron injection layer 24e in this order from the lower layer side. An electron blocking layer and a hole blocking layer may be provided on the functional layer 24. The light-emitting layer 24c is formed in an island shape in the opening (for each sub-pixel) of the edge cover film 23 by vapor deposition, ink jet, or photolithography. The other layers are formed in an island shape or in a whole (common layer). Further, one or more layers (described later) of the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer may not be formed.

Fig. 1 shows a configuration in which the anode (first electrode 22), the functional layer 24, and the cathode (second electrode 25) are provided in this order from the TFT layer 4 side, but the present invention is not limited to this. The cathode, the functional layer 24, and the anode may be provided in this order from the TFT layer 4 side. In this case, the functional layer 24 is formed by stacking an electron injection layer 24e, an electron transport layer 24d, a light-emitting layer 24c, a hole transport layer 24b, and a hole injection layer 24a in this order from the lower layer side.

When an organic layer (light emitting layer) of the OLED is formed by evaporation, FMM (fine metal mask) is used. The FMM is a sheet (e.g., made of invar steel material) having a large number of openings, and island-shaped light-emitting layers (corresponding to one sub-pixel) are formed of an organic substance passing through one opening.

A quantum dot layer (light-emitting layer) of a QLED can be formed into an island-shaped quantum dot layer (corresponding to one sub-pixel) by, for example, applying a solution in which quantum dots are dispersed in a solvent and patterning the quantum dot layer by an inkjet method or a photolithography method.

The first electrode 22 is formed of a laminate of, for example, ITO (Indium Tin Oxide) and Ag (silver) or an alloy containing Ag, and has light reflectivity. The second electrode 25 (cathode) is configured to include a metal nanowire (e.g., silver nanowire) and have high light transmittance, as described later.

In the case where the light-emitting element Xr · Xg · Xb is an OLED, holes and electrons are recombined in the light-emitting layer by a driving current between the first electrode 22 and the second electrode 25, and light is emitted in a process in which excitons thus generated are transferred to a base state. Since the second electrode 25 has high light transmittance and the first electrode 22 has light reflectivity, light emitted from the functional layer 24 is emitted upward as a top emission.

When the light emitting element Xr · Xg · Xb is a QLED, holes and electrons are recombined in the light emitting layer by a driving current between the first electrode 22 and the second electrode 25, and excitons generated thereby emit light (fluorescence) in a process of converting from a conduction band level (conduction band) to a valence band level (valence band) of the quantum dots.

In the light-emitting element layer 5, light-emitting elements (inorganic light-emitting diodes, etc.) other than the above-described OLED and QLED may be formed.

The sealing layer 6 has light transmittance and includes an inorganic sealing film 26 directly formed on the second electrode 25 (in contact with the second electrode 25), an organic film 27 on the upper layer than the inorganic sealing film 26, and an inorganic sealing film 28 on the upper layer than the organic film 27. The sealing layer 6 covering the light emitting element layer 5 prevents foreign substances such as water and oxygen from penetrating into the light emitting element layer 5.

The organic film 27 has a flattening effect and light transmittance, and can be formed using an organic material that can be applied, for example, by inkjet application. The inorganic sealing films 26 and 28 are inorganic insulating films, and may be formed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminate film thereof formed by CVD.

The functional film 39 has at least one of an optical compensation function, a touch sensor function, and a protection function, for example.

Fig. 2 (a) is a photograph showing the structure of the second electrode, fig. 2 (b) is a perspective view showing the structure of the second electrode, and fig. 2 (c) is a schematic view showing the length of the metal nanowire. Fig. 3 is a graph showing the effect of the present embodiment.

In the present embodiment, since the second electrode 25 as the upper electrode is formed of the mesh-like silver nanowires as shown in fig. 2 (a) and (b), it is understood that the light transmittance (CA) of the second electrode 25 (the diameter of the silver nanowire is 25nm, and the maximum number of superposed layers is 5 layers) is higher than the light transmittance (CA) of the silver thin film electrode (thickness 20nm) as the comparison object in the wavelength region of 380(nm) to 780(nm) and exceeds 80% in the wavelength region of 400(nm) to 780(nm), as shown in fig. 3. It is also found that the light Reflectance (RB) of the second electrode 25 is lower than the light Reflectance (RB) of the silver thin film electrode as a comparison target in the wavelength region of 380(nm) to 780(nm), and is less than 15% in the wavelength region of 400(nm) to 780 (nm).

As described above, by forming the second electrode 25 as the common electrode by the silver nanowires NW having a mesh shape, it is possible to improve the light extraction efficiency in the top emission structure and obtain good viewing angle characteristics.

In addition, the number of the silver nanowire overlapping layers of the second electrode 25 is 2 to 8, preferably 3 to 6. The diameter (phi) of the silver nanowires is 5 to 100(nm), preferably 10 to 80(nm), and more preferably 20 to 50 (nm). The length (track length) of the silver nanowires is 1 to 100 (mu m), preferably 5 to 50 (mu m), and more preferably 8 to 30 (mu m). These values can be obtained by observation with a scanning electron microscope or the like. The silver nanowires have a resistance (surface resistance) of 5 to 200(Ω/Sq), preferably 10 to 100(Ω/Sq), and more preferably 10 to 50(Ω/Sq).

As shown in fig. 2 c, the length (average track length) of the metal nanowire such as the silver nanowire NW is preferably smaller than the distance (terminal gap width) Pc between the adjacent terminals TM1 and TM2 of the terminal portion. In this way, even if the metal nanowire is mixed into the terminal portion when the second electrode is formed, the occurrence of short circuit between the terminals TM1 and TM2 due to the metal nanowire can be prevented.

In the first embodiment, Ag is used as the material of the metal nanowire of the second electrode, but the present invention is not limited thereto. The nanowire may be a single metal nanowire composed of any one of Au, Al, and Cu, or may be a nanowire including an alloy of 2 or more of Ag, Au, Al, and Cu.

Fig. 4(a) and (b) are graphs showing the effect of the second electrode (metal nanowire electrode) when the light-emitting element has a quantum dot light-emitting layer. As shown in fig. 4(a), with respect to the characteristics of the polar angle and the normalized light emission intensity, it is found that the light distribution characteristics FS (the thicknesses of the carrier injection layer, the carrier transport layer, and the light emitting layer are shared between colors) are close to Lambertian among all the three colors, compared with the characteristics (the characteristics FR of red, the characteristics FG of green, and the characteristics FB of blue) when the light emitting layer as the quantum dot layer and the second electrode (metal nanowire electrode) 25 are combined and the characteristics (the characteristics FR of red, the characteristics FG of green, and the characteristics FB of blue) when the light emitting layer as the quantum dot layer and the silver thin film electrode are combined. The lambertian orientation characteristic is an ideal light distribution characteristic in which the radiation intensity in the angle θ direction is expressed by cos θ times of the radiation intensity on the optical axis, with the vertical front surface set to 0 °.

As shown in fig. 4b, in the red light emission characteristic Ka after the combination of the light emitting layer (red light emission, for example, PL peak wavelength of 620nm and half width of 25nm) as the quantum dot layer and the silver thin film electrode having a large light reflectance, a cavity effect (resonance effect) between the electrodes adversely affects that the peak wavelength shifts to the long wavelength side and exceeds 630nm and the half width increases to 32nm, but in the red light emission characteristic Ka after the combination of the light emitting layer (red light emission) as the quantum dot layer and the second electrode (metal nanowire electrode), the peak wavelength is at an appropriate position (about 620nm) and the half width is about 25nm and hardly changes.

Thus, in the case of using the metal nanowire having high transmittance for the second electrode, the cavity effect is not substantially exhibited. Therefore, by applying to the QLED which has an adverse effect due to the cavity effect, a greater effect (i.e., an effect of improving the viewing angle characteristic) can be obtained. Further, as shown in fig. 4(a), since the cavity effect is hardly exhibited, even if the film thickness of each layer between the first electrode 22 and the second electrode 25 does not match the optimum value among the light emitting elements Xr, Xg, Xb, it is possible to approximate lambertian light distribution and to make the film thickness of each layer common. This makes it possible to easily manufacture the display device 2 having excellent viewing angle characteristics.

Fig. 5 is a flowchart illustrating a manufacturing method of the display device 2. In step S1, the barrier layer 3 and the TFT layer 4 are formed on the base material 12. In step S2, the first electrode 22 is formed on the planarization film 21 using sputtering and photolithography. In step S3, the edge cover film 23 is formed. In step S4, an HTL layer (hole transport layer) is formed. In step S5, a light-emitting layer (e.g., a quantum dot layer) is formed. In step S6, an ETL layer (electron transport layer, e.g., zinc oxide nanoparticle layer) is formed. In step S7, a silver nanowire ink in which silver nanowires are dispersed in a solvent is coated on the ETL layer. The silver nanowire ink may contain a binder, a dispersant, and other additives. In step S8, the silver nanowire ink is applied and dried (solvent is removed), and a second electrode 25 including silver nanowires NW in a mesh shape is formed on the ETL layer as shown in fig. 2. In step S9, the material (precursor) of the organic film 27 is ink-jet coated and cured so as to directly cover the second electrode 25, thereby forming the organic film 27. In step S10, the inorganic sealing film 28 is formed on the upper layer of the organic film 27.

In the first embodiment, since the second electrode 25 is formed by coating and drying the silver nanowire ink, there is an advantage that the influence on the light-emitting layer (for example, quantum dot light-emitting layer) is small as compared with the case of using the sputtering method or the evaporation method. As a result, the light emission characteristics of the display device 2 can be prevented from being degraded.

The second electrode 25 made of the mesh-like silver nanowires NW is more flexible than a general Ag film and the like, and is therefore preferable as a common electrode of the flexible display device 2.

Fig. 6 (a) is a plan view showing the structure of the display device according to the first embodiment, and fig. 6 (b) is a sectional view of an edge. As shown in fig. 6, in the frame area NA, a groove TN is formed in the planarization film 21, and bank portions BK1 and BK2 defining the end portions of the organic film 27 are provided on the outer side of the groove TN.

In fig. 6, a conductive film AW formed in the same layer and of the same material as the first electrode 22 of fig. 1 crosses the trench TN and overlaps the bank portions BK2 on the outer side. In the trench TN, the edge cover film 23 penetrates, and the second electrode 25 is in contact with (electrically connected to) the conductive film AW. The power supply main wirings MW (on the same layer as the source wiring SH in fig. 1) included in the third metal layer are formed so as to overlap the banks BK1 and BK 2.

In a plan view, the grooves TN surround the display region DA, the bank portions BK1 surround the grooves TN, and the bank portions BK2 surround the bank portions BK 1. The bank BK1 is formed of the planarizing film 21 and the edge cover film 23, and is a liquid barrier structure for blocking droplets during the formation of the organic film 27. The bank BK2 is a member for blocking liquid droplets that exceed the bank BK 1.

Frame-shaped projections Qa and Qb (double structure) formed of the same material as the edge cover film 23 in the same layer are provided between the trench TN and the bank BK1 in plan view; and a plurality of photo spacers PS located outside the projections Qa, Qb, the projections Qb defining the end portions of the second electrode 25. That is, when the silver nanowire ink, which is a material of the second electrode 25, is applied, the convex portion Qb becomes a liquid barrier portion. Further, the inner convex portion Qa may define an end portion (which becomes a liquid blocking portion) of the second electrode 25. The photo spacer PS is formed of the edge cover film 23, and has a film thickness larger than the projections Qa and Qb. The upper surface of the photo spacer PS serves as a mask contact surface (the projections Qa and Qb do not contact the mask) when the vapor deposited film is formed on the first electrode 22 (see fig. 1). The frame-shaped projection is not limited to the double structure, and may be a single structure.

A contact groove CM1 penetrating the edge cover film 23 and the planarization film 21 is formed inside the bank BK1, a contact groove CM2 penetrating the edge cover film 23 and the planarization film 21 is formed between the bank BK1 and the bank BK2, and the power supply main wiring MW is exposed in the contact grooves CM1 and CM2 and is in contact with the conductive film AW (the power supply main wiring MW is electrically connected to the conductive film AW). The cathode power supply voltage (ELVSS) is supplied from the power supply main wiring MW to the second electrode 25 via the conductive film AW.

Fig. 7 (a) is a plan view showing a first modification of fig. 6, and fig. 7 (b) is a sectional view of an edge. As shown in fig. 7, the end portions of the second electrodes 25 may be defined for the banks BK 1. That is, the bank BK1 serves as a liquid barrier when the silver nanowire ink is applied. The edge of the organic film 27 is defined by the bank BK1, but is not limited thereto, and the edge of the organic film 27 may also be defined by the bank BK 2. Further, a frame-shaped bank surrounding the bank BK2 may be provided outside (on the panel edge side) the bank BK 2.

Fig. 8(a) is a plan view showing a second modification of fig. 6, and fig. 8 (b) is a sectional view of an edge. As shown in fig. 8, the end portion of the second electrode 25 may be defined for the groove TN. That is, when the silver nanowire ink is applied, the groove TN is filled with the silver nanowire ink, and becomes a liquid barrier.

Fig. 9(a) is a plan view showing a third modification of fig. 6, and fig. 9 (b) is a sectional view of an edge. As shown in fig. 9, of the four edges surrounding the display area DA, the central portion including the edge Fd of the terminal portion TA may be provided with no groove, and the convex portions Qa and Qb defining the end portion of the second electrode 25 may be provided, and the groove TN may define the end portion of the second electrode 25 on the remaining three edges.

That is, the groove TN is provided so as to surround a part of the four sides of the display area DA along one side of the terminal section TA and all of the other three sides, and a part of the end portion of the second electrode 25 along the one side is defined by the convex section Qb, and another part is defined by the groove TN, and a part of the end portion of the second electrode 25 along the three sides is defined by the groove TN.

[ second embodiment ]

Fig. 10 (a) is a schematic perspective view showing the structure of the second electrode in the second embodiment, fig. 10 (b) is a schematic cross-sectional view showing the structure of the light-emitting element in the second embodiment, and fig. 10 (c) is a graph showing the effects of the structures of fig. 10 (a) and (b). As shown in fig. 10 (a), the second electrode 25 may be configured to include silver nanowires and zinc oxide (ZnO) nanoparticles as an electron transport material. The second electrode 25 in which the silver nanowires and the zinc oxide nanoparticles are mixed is obtained by mixing the silver nanowire dispersion and the zinc oxide nanoparticle dispersion at a desired ratio, and applying and drying the stirred mixture. Specifically, the silver nanowires NW are randomly arranged in three dimensions, and the silver nanowires NW pass through gaps between the zinc oxide nanoparticles NP (average particle diameter of 1 to 30 nm). The light-emitting element according to the second embodiment has a structure in which a first electrode 22 (anode), an HTL layer 24b, a light-emitting layer 24c (for example, a quantum dot light-emitting layer), and a second electrode (common cathode) are provided in this order as shown in fig. 10 (b).

In the structure of fig. 10 a, since the contact area between the silver nanowire NW and the zinc oxide nanoparticles NP as the electron transport material is increased in the second electrode 25, as shown in fig. 10 c, the external quantum effect UB (normalized value with respect to the reference value) of the light-emitting element of the second embodiment is significantly improved in the range of the current density of 0 to 50[ milliamperes/square centimeter ] as compared with the external quantum effect UA (the reference value of each current density is 1) of the light-emitting element having the silver nanowire layer as the second electrode formed on the ETL layer (zinc oxide nanoparticle layer) and the normalized external quantum efficiency UA (normalized value with respect to the reference value) of the light-emitting element having the cathode of a general silver thin film in the structure shown in fig. 2 b.

In addition, the number of steps can be reduced as compared with the case where the ETL layer and the second electrode (common cathode) are formed in different steps.

If the number of the metal nanowires NW is too large, the electron transport ability to the light-emitting layer decreases, and if the number of the metal nanowires NW is too small, the resistance value increases. Therefore, the volume ratio of the metal nanowire NW to the ZnO nanoparticle NP is preferably 1/49 to 1/9, and more preferably 1/25 to 1/15.

The above embodiments are provided for illustrative and descriptive purposes and not for limiting purposes. Based on these illustrations and descriptions, those skilled in the art should appreciate that many variations are possible.

[ conclusion ]

[ means 1]

A display device comprises a display region and a peripheral frame region, including a TFT layer;

a light-emitting element layer including a first electrode, a functional layer, and a second electrode, and having a plurality of light-emitting elements with different emission colors;

a sealing layer including an organic film sealing the light emitting element layer,

the second electrode is common to the plurality of light emitting elements and includes an electrode of a metal nanowire in a mesh shape.

[ means 2]

Such as the display device described in the mode 1,

a planarization film is contained in the TFT layer,

in the frame region, a trench is formed on the planarization film,

outside the trench, a bank portion defining an end of the organic film is disposed.

[ means 3]

Such as the display device described in the mode 2,

a convex portion located between the trench and the bank portion is formed in a frame shape so as to surround the display region in a plan view;

the convex portion defines an end portion of the second electrode.

[ means 4]

For example, the display device according to mode 3 includes a photo spacer positioned between the convex portion and the bank portion in a plan view.

[ means 5]

For example, in the display device according to mode 5, the convex portion is smaller in thickness than the photo spacer.

[ means 6]

Such as the display device described in any one of modes 3 to 5,

the light emitting element layer includes an edge covering film covering an edge of the first electrode,

the convex part and the edge covering film are in the same layer and made of the same material.

[ means 7]

Such as the display device described in any one of modes 2 to 6,

a conductive film of the same layer and formed of the same material as the first electrode is provided across the trench,

the conductive film and the second electrode are in contact within the trench.

[ means 8]

Such as the display device described in any one of modes 2 to 7,

in the frame region, a main wiring is provided below the planarization film,

in the planarization film, a contact groove for exposing the main wiring is provided on the display region side of the bank portion,

the second electrode is electrically connected to the main wiring.

[ means 9]

For example, in the display device described in mode 2, the bank defines an end portion of the second electrode.

[ means 10]

For example, in the display device described in mode 2, the groove defines an end portion of the second electrode.

[ means 11]

For example, in the display device described in mode 10, the groove is provided in a frame shape so as to surround the entire periphery of the display region.

[ means 12]

For example, in the display device according to mode 3, a terminal portion including a plurality of terminals is provided in the frame region,

the groove is provided to surround a part of four sides of the display area along one side of the terminal portion and all of the other three sides,

for a portion along the one side in the end portion of the second electrode, a part is defined by the convex portion, and another part is defined by the groove,

a portion of the end portion of the second electrode along the three sides is defined by the groove.

[ means 13]

For example, in the display device according to any one of modes 1 to 12, a terminal portion including a plurality of terminals is provided in the frame region,

the length of the metal nanowire is smaller than the distance between adjacent terminals.

[ means 14]

For example, in the display device described in any one of modes 1 to 13, the organic film is formed over the second electrode.

[ means 15]

For example, in the display device according to any one of modes 1 to 14, the light-emitting layer is a quantum dot layer.

[ means 16]

For example, in the display device according to any one of modes 1 to 15, the light-emitting layer is an organic layer.

[ means 17]

For example, in the display device according to any one of modes 1 to 16, the light transmittance of the second electrode is 80% or more.

[ means 18]

For example, the display device according to any one of modes 1 to 17, wherein the metal nanowire includes at least one of Ag, Au, Al, and Cu.

[ means 19]

For example, the display device described in any one of modes 1 to 18, wherein the first electrode is an anode,

the second electrode is a cathode and is a cathode,

the second electrode includes an electron transport material.

[ means 20]

For example, in the display device of mode 19, the second electrode is in contact with the light-emitting layer.

[ means 21]

For example, in the display device of mode 19 or 20, the electron transport material is zinc oxide nanoparticles.

[ means 22]

For example, in the display device described in mode 21, the volume ratio of the metal nanowires to the zinc oxide nanoparticles is 1/49 to 1/9.

[ means 23]

A method of manufacturing a display device includes a TFT layer; a light-emitting element layer in which a plurality of light-emitting elements having different emission colors and including a first electrode, a functional layer, and a second electrode are formed; and a sealing layer that includes an organic film and seals the light-emitting element layer, wherein the method for manufacturing the display device includes:

and a step of forming the second electrode by applying an ink in which the metal nanowires are dispersed in a solvent and removing the solvent.

2 display device

4 TFT layer

5 light-emitting element layer

21 planarizing film

22 first electrode

23 edge cover film

24 EL layer (including luminescent layer)

25 second electrode

BK1 BK2 dyke

Xr, Xg, Xb light emitting element

Convex part of Qa and Qb

PS photo spacer

TN groove

CM contact groove

AW conductive film

MW power supply main wiring

NW silver nanowires

NP zinc oxide nanoparticles

DA display area

And (5) an NA frame area.