Electroluminescent display device

Abstract

To provide an electroluminescent display device which is fabricated by a solution process and furthermore enables prevention of flowing of a light emission stack of any one subpixel to another subpixel.SOLUTION: The present disclosure provides an electroluminescent display device including: a substrate including a first subpixel and a second subpixel which are arranged in a first direction; first electrodes which are provided in the first subpixel and the second subpixel, respectively; a bank which is provided in a boundary between the first subpixel and the second subpixel on the substrate; light emission stacks which are provided on the first electrode and the bank, respectively; and a second electrode which is provided in the light emission stack. The bank includes a first bank and a second bank provided in the first bank. The light emission stack is provided in a first layer provided in each of the first subpixel and the second subpixel, and on the first layer, and includes a second layer continuous to the second subpixel from the first subpixel. The first bank is provided on a lower side of the second layer, and the second bank is provided on the second layer.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electroluminescent display device, and more particularly to an electroluminescent display device that can be manufactured using a solution process.

Background Art

[0002] An electroluminescent display device includes a first electrode, a second electrode, and a light-emitting stack provided between the first electrode and the second electrode, and an image is displayed by the light-emitting stack emitting light by an electric field between the two electrodes.

[0003] The light-emitting stack may include an organic substance that emits light while excitons disappear due to recombination of electrons and holes. Excitons are electrically neutral particles including electrostatically bound electrons and holes. When the organic substance absorbs light having an energy higher than its band gap, excitons are generated, and at this time, electrons are excited from the valence band to the conduction band. When the conduction band electrons in the exciton recombine with the holes in the valence band, the exciton disappears, and the energy of the exciton can be converted into light.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The light-emitting stack can be formed by a vacuum deposition process. In this case, however, an expensive vacuum deposition apparatus is required, and the manufacturing cost may increase. Particularly in the case of a large-sized electroluminescent display device, the size of the mask for pattern formation and the vacuum deposition apparatus becomes even larger, and the productivity decreases during mass production.

[0005] Therefore, in order to reduce the manufacturing cost, a scheme has been proposed to form the light-emitting stack by a solution process using an inkjet device or the like.

[0006] However, when forming the light-emitting stack in a solution process, for example, there may occur a problem that a solution for forming a red light-emitting stack flows from a red sub-pixel to an adjacent green sub-pixel, deteriorating the image quality of the green sub-pixel.

[0007] An object of the present invention is to provide an electroluminescent display device capable of preventing a light-emitting stack of one sub-pixel from flowing to another sub-pixel while utilizing a solution process.

Means for Solving the Problems

[0008] To achieve the above object, the present invention includes a substrate including a first sub-pixel and a second sub-pixel arranged in a first direction, a first electrode provided on each of the first sub-pixel and the second sub-pixel on the substrate, a bank provided at a boundary between the first sub-pixel and the second sub-pixel on the substrate, a light-emitting stack provided on the first electrode and the bank, and a second electrode provided on the light-emitting stack. The bank includes a first bank and a second bank provided on the first bank. The light-emitting stack includes a first layer provided on each of the first sub-pixel and the second sub-pixel, and a second layer provided on the first layer and continuous from the first sub-pixel to the second sub-pixel. The first bank is provided under the second layer, and the second bank is provided on the second layer, and provides an electroluminescent display device.

[0009] The present invention also provides an electroluminescent display device including a substrate including a plurality of first sub-pixels and a plurality of second sub-pixels, a boundary between the plurality of first sub-pixels and the plurality of second sub-pixels, a boundary between the plurality of first sub-pixels, and a first bank provided at a boundary between the plurality of second sub-pixels, a second bank provided in a linear structure continuous along a boundary between the plurality of first sub-pixels and the plurality of second sub-pixels, and a third bank provided in a discontinuous linear structure at a boundary between the plurality of first sub-pixels and a boundary between the plurality of second sub-pixels.

Effects of the Invention

[0010] According to the present invention as described above, there are the following effects.

[0011] According to one embodiment of the present invention, the first layer of the light-emitting stack that needs to be separated by sub-pixel is formed by a solution process such as an inkjet process, but by being cut off by the first bank for each sub-pixel, it becomes discontinuous for adjacent sub-pixels.

[0012] According to one embodiment of the present invention, the second layer and the fourth layer of the light-emitting stack that do not need to be separated by sub-pixel can be formed without a mask by a vacuum evaporation method such as an evaporation method.

[0013] According to one embodiment of the present invention, by further forming a second bank on the second layer of the light-emitting stack, while forming the third layer of the light-emitting stack that needs to be separated by sub-pixel by a solution process such as an inkjet process, it is cut off by the second bank and becomes discontinuous for adjacent sub-pixels.

[0014] According to another embodiment of the present invention, a third bank is formed at the boundary between one sub-pixel that emits light of the same hue and another adjacent sub-pixel, but by securing a predetermined space for the movement of the ink, the fluidity of the light-emitting stack is improved, and the problem of mottling occurring in a specific sub-pixel can be prevented.

Brief Description of the Drawings

[0015]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0016] The advantages and features of the present invention, and the method for achieving them, will become apparent by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but is embodied in various different forms, and the present embodiments are merely provided to complete the disclosure of the present invention and to fully inform those with ordinary knowledge in the technical field to which the present invention pertains of the scope of the invention. The present invention is defined only by the scope of the claims.

[0017] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the figures for explaining the embodiments of the present invention are exemplary, and the present invention is not limited to the matters shown in the figures. Throughout the specification, the same reference numerals refer to the same components. Further, in the description of the present invention, when it is determined that a specific description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description thereof is omitted. When terms such as "including", "having", "consisting of", etc. are used in this specification, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes the case of including a plurality unless otherwise explicitly stated.

[0018] In interpreting a component, it is interpreted as including an error range even without a separate explicit description.

[0019] In the case of an explanation of a positional relationship, for example, when the positional relationship between two parts is explained by "on", "above", "below", "next to", etc., one or more other parts can be located between the two parts unless "immediately" or "directly" is used.

[0020] In the case of an explanation of a time relationship, for example, when the time front and back relationship is explained by "after", "subsequent to", "next to", "before", etc., it can include the case of not being continuous unless "immediately" or "directly" is used.

[0021] First, second, etc. are used to explain various components, but these components are not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, the first component mentioned below can be the second component within the technical idea of the present invention.

[0022] The features of each of some examples of this application can be partially or wholly combined or combined with each other, various linkages and drives are technically possible, each embodiment can be implemented independently of each other, and they can also be implemented together in relation to each other.

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0024] FIG. 1 is a schematic plan view of an electroluminescent display device according to an embodiment of the present invention.

[0025] As can be seen from FIG. 1, an electroluminescent display device according to an embodiment of the present invention includes a substrate 100, a plurality of sub-pixels (SP1, SP2, SP3) provided on the substrate 100, a first electrode 300 provided for each of the plurality of sub-pixels (SP1, SP2, SP3), and banks 410, 420 provided in a boundary region between the plurality of sub-pixels (SP1, SP2, SP3).

[0026] The plurality of sub-pixels (SP1, SP2, SP3) may include a first sub-pixel (SP1), a second sub-pixel (SP2), and a third sub-pixel (SP3) arranged in a first direction, for example, the X-axis direction.

[0027] In the first sub-pixel (SP1), light of a first hue may be emitted, in the second sub-pixel (SP2), light of a second hue may be emitted, and in the third sub-pixel (SP3), light of a third hue may be emitted.

[0028] The plurality of first sub-pixels (SP1) can be arranged in a second direction intersecting the first direction, for example, the Y-axis direction. Similarly, the plurality of second sub-pixels (SP2) and the plurality of third sub-pixels (SP3) can also be arranged in the second direction.

[0029] The array structure of such a plurality of sub-pixels (SP1, SP2, SP3) can be changed into various forms known in the art.

[0030] The first electrode 300 can function as an anode of the electroluminescent display device, is patterned for each of the plurality of sub-pixels (SP1, SP2, SP3), and can be surrounded by the banks 410, 420.

[0031] The banks 410 and 420 are provided in a boundary region between the plurality of sub-pixels (SP1, SP2, SP3), and can individually define sub-pixel (SP1, SP2, SP3) regions.

[0032] The banks 410 and 420 include a first bank 410 and a second bank 420.

[0033] The first bank 410 can be formed in a mesh structure in a boundary region between the plurality of sub-pixels (SP1, SP2, SP3). Specifically, the first bank 410 is formed in a boundary region between a first sub-pixel (SP1), a second sub-pixel (SP2), and a third sub-pixel (SP3) arranged in the first direction, and can also be formed in boundary regions between the plurality of first sub-pixels (SP1) arranged in the second direction, between the plurality of second sub-pixels (SP2), and between the plurality of third sub-pixels (SP3).

[0034] The second bank 420 can be formed in a pattern different from that of the first bank 410. Specifically, the second bank 420 is formed in a boundary region between a first sub-pixel (SP1), a second sub-pixel (SP2), and a third sub-pixel (SP3) arranged in the first direction, but may not be formed in boundary regions between the plurality of first sub-pixels (SP1) arranged in the second direction, between the plurality of second sub-pixels (SP2), and between the plurality of third sub-pixels (SP3). Therefore, the second bank 420 can be formed in a stripe structure that extends long in the second direction and is spaced apart at a predetermined interval in the first direction.

[0035] FIG. 2 is a schematic cross-sectional view of an electroluminescent display device according to an embodiment of the present invention, which corresponds to a cross-section taken along line A-B in FIG. 1. That is, FIG. 2 is a cross-sectional view including a boundary region between a first sub-pixel (SP1), a second sub-pixel (SP2), and a third sub-pixel (SP3) that emit light of different hues.

[0036] As can be seen from FIG. 2, an electroluminescent display device according to an embodiment of the present invention includes a substrate 100, a circuit element layer 200, a first electrode 300, banks 410 and 420, a light-emitting stack 500, a second electrode 600, a sealing layer 700, a color filter 800, a light-shielding layer 850, and a protective layer 900.

[0037] The substrate 100 can be made of glass or transparent plastic, but is not necessarily limited thereto, and can also be made of a semiconductor material such as a silicon wafer. When the electroluminescent display device according to an embodiment of the present invention is of a top emission type, not only a transparent material but also an opaque material can be used as the material of the substrate 100. However, when the light emitted by the electroluminescent display device according to an embodiment of the present invention is of a bottom emission type, a transparent material is used as the material of the substrate 100.

[0038] The circuit element layer 200 is formed on the substrate 100.

[0039] The circuit element layer 200 includes a driving thin film transistor.

[0040] The driving thin film transistor includes an active layer 210 provided on the substrate 100, a gate insulating film 220 provided on the active layer 210, a gate electrode 230 provided on the gate insulating film 220, an interlayer insulating film 240 provided on the gate electrode 230, and a source electrode 251 and a drain electrode 252 provided on the interlayer insulating film 240 and connected to the active layer 210 through holes provided in the interlayer insulating film 240 and the gate insulating film 220. The figure shows a driving thin film transistor having a top gate structure in which the gate electrode 230 is provided on the active layer 210, but the present invention can include a driving thin film transistor having a bottom gate structure in which the gate electrode 230 is provided under the active layer 210.

[0041] The circuit element layer 200 may further include a passivation layer 260 and a planarization layer 270 provided on the driving thin film transistor. The passivation layer 260 is provided on the source electrode 251 and the drain electrode 252, and the planarization layer 270 is provided on the passivation layer 260.

[0042] The passivation layer 260 and the planarization layer 270 are provided with contact holes, and the first electrode 300 can be connected to the drain electrode 252 through the contact holes. In some cases, the first electrode 300 can also be connected to the source electrode 251 through the contact holes.

[0043] On the other hand, in addition to the driving thin film transistor, the circuit element layer 200 may further include various signal wirings including gate wirings, data wirings, power supply wirings, and reference wirings, various thin film transistors including switching thin film transistors and sensing thin film transistors, and capacitors.

[0044] The switching thin film transistor is switched by a gate signal supplied to the gate wiring and serves to supply a data voltage supplied from the data wiring to the driving thin film transistor.

[0045] The driving thin film transistor is switched by a data voltage supplied from the switching thin film transistor and serves to generate a data current from a power supply supplied by the power supply wiring and supply it to the first electrode 300.

[0046] The sensing thin film transistor serves to sense a threshold voltage deviation of the driving thin film transistor that causes image quality degradation, and supplies the current of the driving thin film transistor to the reference wiring in response to a sensing control signal supplied from the gate wiring or a separate sensing wiring.

[0047] The capacitor serves to maintain the data voltage supplied to the driving thin-film transistor for one frame, and is connected to the gate terminal and the source terminal of the driving thin-film transistor, respectively.

[0048] Each of the switching thin-film transistor, the driving thin-film transistor, and the sensing thin-film transistor can be changed to various structures known in the art, such as a bottom gate structure or a top gate structure.

[0049] In addition, the circuit element layer 200 may further include a passivation layer for protecting the switching thin-film transistor, the driving thin-film transistor, and the sensing thin-film transistor, and a planarization layer provided on the passivation layer.

[0050] The first electrode 300 is formed on the circuit element layer 200 separately for each sub-pixel (SP1, SP2, SP3). The first electrode 300 can function as an anode of the electroluminescent display device. Such a first electrode 300 may include a transparent electrode when the electroluminescent display device according to the present invention is a bottom emission type, and may include a reflective electrode when the electroluminescent display device according to the present invention is a top emission type.

[0051] The banks 410 and 420 are provided on the circuit element layer 200 and include a first bank 410 and a second bank 420.

[0052] The first bank 410 is formed on the circuit element layer 200 so as to cover both ends of the first electrode 300, and is formed at the boundary between a plurality of sub-pixels (SP1, SP2, SP3).

[0053] The first bank 410 can be formed in a two-layer structure of a lower bank layer 410a and an upper bank layer 410b.

[0054] The lower bank layer 410a can be formed to be in contact with the first electrode 300 and the circuit element layer 200. The lower bank layer 410a can be formed with a thickness thinner than that of the upper bank layer 410b and a width wider than that of the upper bank layer 410b. The lower bank layer 410a can be made of a hydrophilic substance, but is not necessarily limited thereto, and may be made of a hydrophobic substance in some cases.

[0055] The upper bank layer 410b is patterned on the lower bank layer 410a. The upper bank layer 410b is formed at the boundary between the first sub-pixel (SP1) and the second sub-pixel (SP2) and at the boundary between the second sub-pixel (SP2) and the third sub-pixel (SP3). As can be seen from FIG. 7 described later, the boundaries between a plurality of first sub-pixels (SP1), the boundaries between a plurality of second sub-pixels (SP2), and the boundaries between a plurality of third sub-pixels (SP3) may not be formed.

[0056] The upper bank layer 410b can be patterned by a photolithography process after applying a solution in which a hydrophobic substance such as fluorine is mixed with a hydrophilic organic insulator. By the light irradiated during the photolithography process, a hydrophobic substance such as fluorine can move to the upper side of the upper bank layer 410b, whereby the upper part of the upper bank layer 410b can have hydrophobic properties and other parts can have hydrophilic properties. That is, the lower part of the upper bank layer 410b in contact with the lower bank layer 410a can have hydrophilic properties, and the upper part of the upper bank layer 410b can have hydrophobic properties. However, it is not necessarily limited thereto, and the entire part of the upper bank layer 410b can be provided to have hydrophobic properties. In this way, the problem that the solution for forming the light-emitting stack 500, particularly the first layer 510, spreads and mixes between adjacent sub-pixels (SP1, SP2, SP3) can be prevented by the upper part of the upper bank layer 410b having hydrophobic properties.

[0057] The second bank 420 is formed at the boundary between a plurality of sub-pixels (SP1, SP2, SP3) above the first bank 410. A second layer 520 of the light-emitting stack 500 is provided between the second bank 420 and the first bank 410, and thus the second bank 420 is provided so as not to contact the first bank 410. The width of the second bank 420 can be formed smaller than the width of the first bank 410, but is not necessarily limited thereto. The light-emitting stack 500 can include a plurality of layers made of different materials, some of which may emit light and some of which may not emit light, but light emission can be facilitated by other layers within the light-emitting stack 500. As an example, the light-emitting stack 500 can include one or more organic light-emitting stacks. Further, the light-emitting stack 500 can include at least one layer among a hole injection layer, a hole transport layer, a charge generation layer, an electron transport layer, and / or an electron injection layer.

[0058] The second bank 420 can be formed of the same material as the upper bank layer 410b through the same process, whereby the lower part of the second bank 420 can have hydrophilic properties and the upper part of the second bank 420 can have hydrophobic properties. Also, the entire portion of the second bank 420 can be provided to have hydrophobic properties. In this way, the upper part of the second bank 420 having hydrophobic properties can prevent a problem in that a solution for forming the third layer 530 of the light-emitting stack 500 spreads and mixes between adjacent sub-pixels (SP1, SP2, SP3).

[0059] The light-emitting stack 500 is formed on the first electrode 300 and the banks 410, 420. The light-emitting stack 500 includes a first layer 510, a second layer 520, a third layer 530, and a fourth layer 540 stacked in order.

[0060] The first layer 510 is formed on the first electrode 300 by a solution process using an inkjet device or the like. The first layer 510 includes a light-emitting layer of an organic substance that causes light emission.

[0061] The first layer 510 is patterned within a plurality of sub-pixels (SP1, SP2, SP3) and is discontinuous and interrupted between the plurality of sub-pixels (SP1, SP2, SP3). That is, the first layer 510 within the first sub-pixel (SP1), the first layer 510 within the second sub-pixel (SP2), and the first layer 510 within the third sub-pixel (SP3) are interrupted without being connected to each other, thereby preventing light emission from occurring in the boundary region between the sub-pixels (SP1, SP2, SP3).

[0062] Since the upper part of the upper bank layer 410b has a hydrophobic property, the first layer 510 does not spread to the upper part of the upper bank layer 410b and is patterned in a discontinuous and interrupted state within a plurality of sub-pixels (SP1, SP2, SP3).

[0063] The first layer 510 is formed to be in contact with the lower bank layer 410a of the first bank 410. Although not shown in detail in the figure, it can extend to the upper bank layer 410b of the first bank 410 and also be in contact with the side surface of the upper bank layer 410b.

[0064] The second layer 520 can be formed on the first layer 510 by a vapor deposition process such as a evaporation method. The second layer 520 does not include a light-emitting stack of an organic substance that causes light emission. Instead, it can include a functional layer that injects or transports electrons or a functional layer that generates charges.

[0065] The second layer 520 can be formed to be continuous without interruption throughout the internal regions and boundary regions of the plurality of sub-pixels (SP1, SP2, SP3). Therefore, the second layer 520 in the first sub-pixel (SP1), the second layer 520 in the second sub-pixel (SP2), and the second layer 520 in the third sub-pixel (SP3) are connected to each other without being disconnected. In other words, the second layer 520 is continuous from the first sub-pixel (SP1) to the third sub-pixel (SP3). The second layer 520 can cover the entire upper surface of the first bank 410.

[0066] The third layer 530 is formed on the second layer 520 by a solution process using an inkjet device or the like. The third layer 530 includes an emitting stack of an organic substance that causes light emission.

[0067] The third layer 530 is patterned within the plurality of sub-pixels (SP1, SP2, SP3) and is disconnected without being continuous between the plurality of sub-pixels (SP1, SP2, SP3). That is, the third layer 530 in the first sub-pixel (SP1), the third layer 530 in the second sub-pixel (SP2), and the third layer 530 in the third sub-pixel (SP3) are disconnected from each other without being connected, thereby preventing light emission from occurring in the boundary regions between the sub-pixels (SP1, SP2, SP3).

[0068] According to an embodiment of the present invention, in order for the third layer 530 to be disconnected without being continuous between the plurality of sub-pixels (SP1, SP2, SP3), before forming the third layer 530, the second bank 420 is further formed on the upper surface of the second layer 520.

[0069] Specifically, although the second layer 520 is formed to be continuous at the boundary regions between a plurality of sub-pixels (SP1, SP2, SP3), the upper surface of the second layer 520 cannot have hydrophobic properties. Therefore, if the third layer 530 is formed on the upper surface of the second layer 520 by a solution process without further forming the second bank 420, the third layer 530 may flow out to the boundary regions between the plurality of sub-pixels (SP1, SP2, SP3). In that case, since the third layer 530 is formed to be continuous between adjacent sub-pixels (SP1, SP2, SP3), a problem may occur where light emission occurs at the boundary regions between the plurality of sub-pixels (SP1, SP2, SP3).

[0070] Therefore, in one embodiment of the present invention, the second bank 420 is further formed on the upper surface of the second layer 520, and by making the upper part of the second bank 420 have hydrophobic properties, when the third layer 530 is formed by a solution process such as an inkjet process, the third layer 530 cannot spread on the upper surface of the second bank 420. As a result, the third layer 530 is pattern-formed in a state of being discontinuous within the plurality of sub-pixels (SP1, SP2, SP3) without being continuous, and the problem of light emission occurring at the boundary regions between the plurality of sub-pixels (SP1, SP2, SP3) can be prevented.

[0071] The fourth layer 540 can be formed on the third layer 530 by a deposition process such as an evaporation method. The fourth layer 540 does not include a light-emitting stack of an organic substance that causes light emission, and instead may include a functional layer that injects or transports electrons. The fourth layer 540 can be formed to be continuous without interruption throughout the internal regions and their boundary regions of the plurality of sub-pixels (SP1, SP2, SP3). Therefore, the fourth layer 540 in the first sub-pixel (SP1), the fourth layer 540 in the second sub-pixel (SP2), and the fourth layer 540 in the third sub-pixel (SP3) are connected to each other without being interrupted. In other words, the fourth layer 540 is continuous from the first sub-pixel (SP1) to the third sub-pixel (SP3). The fourth layer 540 can cover the entire upper surface of the second bank 420.

[0072] Figure 3 is a schematic cross-sectional view of a light-emitting stack 500 according to an embodiment of the present invention. The light-emitting stack 500 can include a plurality of layers, as well as the plurality of different stacks and sub-stacks from each other. Various embodiments of the light-emitting stack 500 will be described below.

[0073] As can be seen from FIG. 3, a light-emitting stack 500 according to an embodiment of the present invention includes a first stack (1 st Stack) that emits light of a first hue, a second stack (2 nd Stack) that emits light of a second hue, and charge generation layers (N-CGL, P-CGL) provided between the first stack and the second stack. The first hue light emitted from the first stack (1 st Stack) and the second hue light emitted from the second stack (2 nd Stack) can be mixed to emit white light from the light-emitting stack 500.

[0074] The first stack (1 st Stack) includes a hole injection layer (HIL), a first hole transport layer (1 st HTL), a first light-emitting stack (1 st EML), and a first electron transport layer (1 st ETL). The second stack (2 nd Stack) can include a second hole transport layer (2 nd HTL), a second light-emitting stack (2 nd EML), a second electron transport layer (2 nd ETL), and an electron injection layer (EIL).

[0075] The first light-emitting stack (1 st EML) emits blue light, and the second light-emitting stack (2 nd EML) can emit yellow-green light. Also, the first light-emitting stack (1 st EML) can emit yellow-green light, and the second light-emitting stack (2 nd EML) can emit blue light.

[0076] The charge generation layer (N-CGL, P-CGL) includes an N-type charge generation layer (N-CGL) and a P-type charge generation layer (P-CGL). The N-type charge generation layer (N-CGL) is formed on the first stack (1 st Stack) and provides electrons to the first stack (1 st Stack). The P-type charge generation layer (P-CGL) is formed on the N-type charge generation layer (N-CGL) and provides holes to the second stack (2 nd Stack).

[0077] Referring to FIG. 2 described above, the first layer 510 formed in the solution process may include some layers of the first stack (1 st Stack). Specifically, it may include the hole injection layer (HIL), the first hole transport layer (1 st HTL), and the first emission stack (1 st EML).

[0078] The second layer 520 formed in the vapor deposition process may include the remaining layers of the first stack (1 st Stack) and the charge generation layer (N-CGL, P-CGL). Specifically, it may include the first electron transport layer (1 st ETL), the N-type charge generation layer (N-CGL), and the P-type charge generation layer (P-CGL).

[0079] The third layer 530 formed in the solution process may include some layers of the second stack (2 nd Stack). Specifically, it may include the second hole transport layer (2 nd HTL) and the second emission stack (2 nd EML).

[0080] The fourth layer 540 formed in the vapor deposition process may include the remaining layers of the second stack (2 nd Stack). Specifically, it may include the second electron transport layer (2 nd ETL) and the electron injection layer (EIL).

[0081] When forming the upper layer of the first light-emitting stack (1 st EML) by a solution process, the first light-emitting stack (1 st EML) may be adversely affected by the solvent in the solution. Therefore, the upper layer of the first light-emitting stack (1 st EML) may preferably be formed by a vapor deposition process. Similarly, the upper layer of the second light-emitting stack (2 nd EML) may also preferably be formed by a vapor deposition process. For such reasons, the second layer 520 and the fourth layer 540 can be formed by a vapor deposition process instead of a solution process.

[0082] Referring to FIG. 2 again, the second electrode 600 is formed on the light-emitting stack 500. The second electrode 600 can be formed to be continuous without interruption throughout the internal regions and boundary regions of the plurality of sub-pixels (SP1, SP2, SP3). The second electrode 600 can function as the cathode of the electroluminescent display device. Such a second electrode 600 can be composed of a transparent electrode or a semi-transparent electrode when the electroluminescent display device according to the present invention is an upper emission type, and can be composed of a reflective electrode when the electroluminescent display device according to the present invention is a lower emission type.

[0083] The encapsulation layer 700 is formed on the second electrode 600 and serves to prevent external moisture or oxygen from penetrating into the light-emitting stack 500.

[0084] The color filter 800 and the light-shielding layer 850 can be formed on the encapsulation layer 700. The color filter 800 may include a red (R) color filter provided in the first sub-pixel (SP1), a green (G) color filter provided in the second sub-pixel (SP2), and a blue (B) color filter provided in the third sub-pixel (SP3). The light-shielding layer 850 can be formed in the region between the red (R) color filter, the green (G) color filter, and the blue (B) color filter, that is, in the boundary region between the plurality of sub-pixels (SP1, SP2, SP3).

[0085] When the electroluminescent display device according to an embodiment of the present invention is of the top emission type, as shown in the figure, the color filter 800 and the light shielding layer 850 can be formed on the upper surface of the sealing layer 700. However, when the electroluminescent display device according to an embodiment of the present invention is of the bottom emission type, the color filter 800 and the light shielding layer 850 can be formed below the light emitting stack 500, for example, in the circuit element layer 200.

[0086] The protective layer 900 is formed on the color filter 800 and the light shielding layer 850 and can serve to protect the internal components from external impacts.

[0087] Figs. 4 to 6 are schematic cross-sectional views of electroluminescent display devices according to various embodiments of the present invention.

[0088] Fig. 4 is different from the electroluminescent display device according to Fig. 2 described above in that the configuration of the upper bank layer 411b of the first bank 410 is changed.

[0089] As can be seen from Fig. 4, a home (H) is provided on the upper surface of the upper bank layer 411b of the first bank 410. Thereby, the second layer 521 of the light emitting stack 500 formed on the upper bank layer 411b extends along the inner surface of the home (H), and the lower part of the second bank 421 formed on the second layer 521 is provided so as to fill the home (H). The second layer 521 is formed by a vapor deposition process.

[0090] According to the structure of Fig. 4, the anode of this embodiment, which is a conductive layer, is formed by a vapor deposition process, an organic light emitting stack is formed by an inkjet printing process immediately above it, a second conductive layer is formed by a vapor deposition process immediately above it, and a second organic light emitting stack can be formed by an inkjet printing process immediately above it.

[0091] According to the structure as shown in FIG. 4, the current path of the second layer 521 of the light-emitting stack 500 is increased by the home (H) formed on the upper surface of the upper bank layer 411b, and there is an advantage that the generation of leakage current between the third sub-pixel (SP3) and the second sub-pixel (SP2) is reduced.

[0092] FIG. 5 is different from the electroluminescent display device according to FIG. 4 described above in that the structure of the home (H) formed on the upper surface of the upper bank layer 412b is changed.

[0093] According to FIG. 4 described above, the home (H) formed on the upper surface of the upper bank layer 411b is formed without penetrating the upper bank layer 411b. As a result, the second layer 521 of the light-emitting stack 500 only contacts the upper bank layer 411b in the region corresponding to the home (H), and does not contact the lower bank layer 410a below it.

[0094] On the other hand, according to FIG. 5, the home (H) formed on the upper surface of the upper bank layer 412b is formed so as to penetrate the upper bank layer 412b. As a result, the second layer 522 of the light-emitting stack 500 contacts the lower bank layer 410a in the region corresponding to the home (H), and the lower part of the second bank 422 formed on the second layer 522 is provided so as to fill the home (H).

[0095] The structure according to FIG. 5 has an advantage that the current path of the second layer 522 of the light-emitting stack 500 in the home (H) region is increased and the generation of leakage current between the third sub-pixel (SP3) and the second sub-pixel (SP2) is reduced as compared with the structure according to FIG. 4.

[0096] FIG. 6 is different from the electroluminescent display device according to FIG. 5 described above in that the structure of the second bank 423 is changed.

[0097] According to FIG. 5 described above, the upper surface of the second bank 422 has a structure provided at a height higher than the upper surface of the second layer 522.

[0098] In contrast, according to FIG. 6, the upper surface of the second bank 423 has a structure provided at the same height as the upper surface of the second layer 522. Even if the upper surface of the second bank 423 is provided at the same height as the upper surface of the second layer 522, since the upper surface of the second bank 423 has hydrophobic properties, when forming the third layer 530 in the solution process, the third layer 530 can be made discontinuous and interrupted on the upper surface of the second bank 423.

[0099] FIG. 7 is a schematic cross-sectional view of an electroluminescent display device according to an embodiment of the present invention, which corresponds to the cross-section taken along line C-D of FIG. 1. That is, FIG. 7 is a cross-sectional view including a boundary region between one first sub-pixel (SP1) that emits light of the same hue as each other and another adjacent first sub-pixel (SP1).

[0100] As can be seen from FIG. 7, an electroluminescent display device according to an embodiment of the present invention includes a substrate 100, a circuit element layer 200, a first electrode 300, a lower bank layer 410a of the first bank 410, a light-emitting stack 500, a second electrode 600, a sealing layer 700, a color filter 800, a light-shielding layer 850, and a protective layer 900.

[0101] The configurations of the substrate 100, the circuit element layer 200, the first electrode 300, the second electrode 600, the sealing layer 700, the color filter 800, the light-shielding layer 850, and the protective layer 900 are the same as those in FIG. 2 described above, so repeated explanations will be omitted.

[0102] According to an embodiment of the present invention, only the lower bank layer 410a of the first bank 410 is formed in the boundary region between one first sub-pixel (SP1) and another adjacent first sub-pixel (SP1), and the upper bank layer 410b of the first bank 410 and the second bank 420 are not formed.

[0103] In one first sub-pixel (SP1) and another first sub-pixel (SP1) adjacent thereto, since light of the same hue is emitted from each other, even if the first layer 510 of the light-emitting stack 500 and the third layer 530 of the light-emitting stack 500 are continuous between one first sub-pixel (SP1) and another first sub-pixel (SP1), it does not have a significant adverse effect on the image quality. Therefore, in the boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1) adjacent thereto, the upper bank layer 410b and the second bank 420 can be omitted.

[0104] Thereby, in the boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1), the second layer 520 of the light-emitting stack 500 comes into contact with the entire upper surface of the lower bank layer 410a. Also, in the boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1), the fourth layer 540 of the light-emitting stack 500 comes into contact with the upper surface of the second layer 520 of the light-emitting stack 500. The fourth layer 540 can be formed by a deposition process such as sputtering.

[0105] FIG. 8 is a schematic plan view of an electroluminescent display device according to another embodiment of the present invention. FIG. 8 is the same as the electroluminescent display device according to FIG. 1 described above, except that it further includes a third bank 430. Therefore, only the different configurations will be described below.

[0106] As can be seen from FIG. 8, the third bank 430 is formed in the boundary region between one first sub-pixel (SP1) that emits light of the same hue and another first sub-pixel (SP1) adjacent thereto. Also, the third bank 430 is formed in the boundary region between one second sub-pixel (SP2) that emits light of the same hue and another second sub-pixel (SP2) adjacent thereto. Also, the third bank 430 is formed in the boundary region between one third sub-pixel (SP3) that emits light of the same hue and another third sub-pixel (SP3) adjacent thereto.

[0107] Therefore, the third bank 430 has a linear structure extending in the first direction, for example, the X-axis direction. Here, the third bank 430 does not have a continuous linear structure in the first direction, but has a discontinuous linear structure in the first direction. That is, the third bank 430 provided at the boundary between two adjacent first sub-pixels (SP1) is not connected to the third bank 430 provided at the boundary between two adjacent second sub-pixels (SP2). The third bank 430 can be discontinuous, including a separated part and another part. This example will be understood with reference to FIGS. 8 to 12.

[0108] Also, the third bank 430 is not connected to the second bank 420. Thereby, the third bank 430 is separated from the second bank 420 on one side (for example, the left side) and the other side (for example, the right side) with a predetermined space (S1) therebetween. In other words, the third bank 430 is formed in the region of the boundary region between two adjacent first sub-pixels (SP1) excluding the predetermined space (S1), while corresponding to the region between two second banks 420 on one side and the other side.

[0109] The third bank 430 can be made of the same material as the second bank 420, but is not necessarily limited thereto, and can also be made of a material different from the second bank 420.

[0110] FIG. 9 is a schematic cross-sectional view of an electroluminescent display device according to another embodiment of the present invention, which corresponds to the cross-section taken along the line E-F in FIG. 8. That is, FIG. 9 is a cross-sectional view including a boundary region between one first sub-pixel (SP1) that emits light of the same hue and another adjacent first sub-pixel (SP1).

[0111] As can be seen from FIG. 9, an electroluminescent display device according to another embodiment of the present invention includes a substrate 100, a circuit element layer 200, a first electrode 300, a lower bank layer 410a, a third bank 430, a light-emitting stack 500, a second electrode 600, a sealing layer 700, a color filter 800, a light-shielding layer 850, and a protective layer 900.

[0112] The configurations of the substrate 100, the circuit element layer 200, the first electrode 300, the second electrode 600, the sealing layer 700, the color filter 800, the light shielding layer 850, and the protective layer 900 are the same as those in FIG. 7 described above, so repeated descriptions will be omitted.

[0113] According to another embodiment of the present invention, the lower bank layer 410a of the first bank 410 and the third bank 430 are formed in a boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1) adjacent thereto.

[0114] Here, the third bank 430 is provided between the second layer 520 and the fourth layer 540 of the light emitting stack 500, similarly to the second bank 420 described above.

[0115] Thereby, in the boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1) adjacent thereto, the second layer 520 of the light emitting stack 500 comes into contact with the entire upper surface of the lower bank layer 410a. Also, in the boundary region between one first sub-pixel (SP1) and another first sub-pixel (SP1) adjacent thereto, the fourth layer 540 of the light emitting stack 500 comes into contact with the upper surface of the third bank 430.

[0116] Therefore, the third layer 530 of the light emitting stack 500 formed in one first sub-pixel (SP1) can be prevented from spreading into another first sub-pixel (SP1) adjacent thereto by the third bank 430. For this purpose, the upper surface of the third bank 430 can have hydrophobic properties. However, it is also possible to form the upper surface of the third bank 430 to have hydrophilicity.

[0117] Referring to FIG. 8 again, according to another embodiment of the present invention, the third bank 430 is configured to be separated from the second bank 420 with a predetermined space (S1) therebetween. This is because, during the solution process for forming the third layer 530 of the light-emitting stack 500, the solution can move smoothly through the predetermined space (S1), thereby preventing the generation of streaks.

[0118] More specifically, by forming the third bank 430, the third layer 530 of the light-emitting stack 500 can be separated between two adjacent first sub-pixels (SP1). Here, if the third bank 430 is formed in a straight-line structure that is continuous in the first direction while being in contact with the second bank 420, the solution for forming the third layer 530 of the light-emitting stack 500 will be confined within each first sub-pixel (SP1) and cannot move between adjacent first sub-pixels (SP1). In this case, if the amount of the solution ejected from the inkjet cannot be precisely adjusted, the amount of the solution may be more or less in a specific first sub-pixel (SP1), and streaks may occur.

[0119] In another embodiment of the present invention, by configuring the third bank 430 to be spaced apart from the second bank 420 with a predetermined space (S1) therebetween, the problem of streak generation can be prevented. Specifically, even if the amount of the solution ejected by the inkjet cannot be accurately adjusted, the solution can move between adjacent first sub-pixels (SP1) through the predetermined space (S1), eliminating the problem of the amount of the solution being more or less in a specific first sub-pixel (SP1), thereby preventing the problem of streak generation.

[0120] FIGS. 10 to 12 are schematic plan views of an electroluminescent display device according to various embodiments of the present invention, which are different from the electroluminescent display device according to FIG. 8 described above in that the configuration of the third bank 430 and the predetermined space (S2) is changed.

[0121] Similar to FIG. 8 described above, in the cases of FIGS. 10 to 12 as well, while corresponding to the region between two second banks 420 on one side and the other side, among the boundary regions between two adjacent first sub-pixels (SP1), the third bank 430 is formed in the region excluding a predetermined space (S2).

[0122] Here, according to FIG. 10, the third bank 430a on one side (for example, the left side) extends from the second bank 420 on one side (for example, the left side) in the other side direction (for example, the right side direction), and the third bank 430b on the other side (for example, the right side) extends from the second bank 420 on the other side (for example, the right side) in the one side direction (for example, the left side direction), and the third bank 430a on the one side is separated from the third bank 430b on the other side with a predetermined space (S) therebetween.

[0123] According to FIG. 11, a plurality of third banks 430 are separated from each other with a predetermined space (S3) therebetween, and the third banks 430 arranged on the outermost one side (for example, the left side) and the outermost other side (for example, the right side) are separated from the second bank 420 with a predetermined space (S4) therebetween.

[0124] According to FIG. 12, the third bank 430 extends from the second bank 420 on one side (for example, the left side) in the other side direction (for example, the right side direction), and the third bank 430 is not connected to the second bank 420 on the other side (for example, the right side) and is separated with a predetermined space (S5) therebetween.

[0125] As described above, the positions of the predetermined spaces (S1, S2, S3, S4, S5) in the boundary region between two adjacent first sub-pixels (SP1) can be changed in various ways.

[0126] The embodiments of the present invention have been described in more detail with reference to the accompanying drawings above. However, the present invention is not necessarily limited to such embodiments, and various modifications can be made and implemented within the scope not departing from the technical idea of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to explain it, and the scope of the technical idea of the present invention is not limited by such embodiments. Therefore, it must be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention must be interpreted according to the scope of the claims, and all technical ideas within the equivalent scope shall be construed as being included in the scope of the rights of the present invention.

Explanation of Reference Numerals

[0127] 100: Substrate 200: Circuit Element Layer 300: First Electrode 410: First Bank 420: Second Bank 430: Third Bank 500: Light-Emitting Stack 510, 520, 530, 540: First, Second, Third, Fourth Layers 600: Second Electrode 700: Encapsulation Layer 800: Color Filter 850: Light-Shielding Layer 900: Protection Layer

Claims

1. a substrate including first and second sub-pixels arranged in a first direction; a first electrode provided on the substrate for each of the first sub-pixel and the second sub-pixel; a bank provided on the substrate at a boundary between the first sub-pixel and the second sub-pixel; a light-emitting stack disposed on the first electrode; a second electrode disposed on the light emitting stack; the bank includes a first bank and a second bank provided on the first bank; the light-emitting stack includes a first layer provided in each of the first sub-pixel and the second sub-pixel, and a second layer provided on the first layer and continuous from the first sub-pixel to the second sub-pixel; the first bank is provided under the second layer, and the second bank is provided over the second layer; the substrate further includes another first sub-pixel disposed adjacent to the first sub-pixel in a second direction and emitting light of the same color as the first sub-pixel; a third bank is further provided at a boundary between the first sub-pixel and the another first sub-pixel; The third bank is provided in a boundary region between the first sub-pixel and the another first sub-pixel except for a predetermined space.

2. The electroluminescent display device of claim 1 , wherein the first bank and the second bank are vertically spaced apart from each other with the second layer therebetween and not in contact with each other.

3. the luminescent stack comprising: a third layer provided on the second layer and provided in each of the first sub-pixel and the second sub-pixel; The electroluminescent display device of claim 1 , further comprising: a fourth layer disposed on the third layer and continuous from the first sub-pixel to the second sub-pixel.

4. the first layer provided in the first sub-pixel and the first layer provided in the second sub-pixel are spaced apart from each other with the first bank therebetween; The electroluminescent display device of claim 3 , wherein the third layer provided in the first sub-pixel and the third layer provided in the second sub-pixel are spaced apart from each other with the second bank interposed therebetween.

5. The electroluminescent display device of claim 3 , wherein the second layer and the fourth layer are spaced apart from each other above and below the second bank without contacting each other.

6. The luminescent stack comprises: a first stack emitting light of a first hue; a second stack emitting light of a second hue; a charge generating layer disposed between the first stack and the second stack; the first stack includes the first layer; The electroluminescent display device according to claim 3, wherein the second stack includes the third layer.

7. the first stack includes a hole injection layer, a first hole transport layer, a first light emitting stack, and a first electron transport layer; the second stack includes a second hole transport layer, a second light emitting stack, a second electron transport layer, and an electron injection layer; the charge generation layer includes an N-type charge generation layer and a P-type charge generation layer; the first layer includes the hole injection layer, the first hole transport layer, and the first light-emitting stack; the second layer includes the first electron transport layer, the N-type charge generation layer, and the P-type charge generation layer; the third layer comprises the second hole transport layer and the second light-emitting stack; The electroluminescent display device of claim 6 , wherein the fourth layer comprises the second electron transport layer and the electron injection layer.

8. the lower portion of the first bank has hydrophilic properties; The electroluminescent display device of claim 1 , wherein the top surface of the first bank and the top surface of the second bank have hydrophobic properties.

9. 2 . The electroluminescent display device of claim 1 , wherein a hole is provided on an upper surface of the first bank, the second layer extends along an inner side surface of the hole, and the second bank is provided to fill the hole.

10. The electroluminescent display device according to claim 1 , wherein the height of the upper surface of the second bank is higher than the height of the upper surface of the second layer.

11. The luminescent stack comprises: a third layer provided on the second layer and disposed in each of the first sub-pixel and the second sub-pixel; a fourth layer disposed on the third layer and continuous from the first sub-pixel to the second sub-pixel; the third layer provided in the first sub-pixel and the third layer provided in the other first sub-pixel are spaced apart from each other with the third bank therebetween, The electroluminescent display device of claim 1 , wherein the second layer and the fourth layer are spaced apart from each other above and below the third bank without contacting each other.

12. the first bank is further provided at a boundary between the first sub-pixel and the another first sub-pixel, a first bank provided at a boundary between the first sub-pixel and the second sub-pixel includes a lower bank layer and an upper bank layer; The electroluminescence display device of claim 1 , wherein the first bank provided at the boundary between the first sub-pixel and the another first sub-pixel includes only the lower bank layer.

Images