KR102702327B1 - Organic Light Emitting Diode Display Device - Google Patents

Abstract

The present invention relates to an organic light-emitting diode display device. The organic light-emitting diode display device of the present invention includes a substrate, a first electrode positioned in a pixel area on the substrate, a bank covering an edge of the first electrode and exposing the first electrode, a light-emitting layer on the first electrode within the pixel area, and a second electrode on the light-emitting layer, wherein the bank includes a first bank and a second bank on the first bank, the first bank includes a protrusion protruding into the pixel area from a side surface of the second bank, the protrusion of the first bank has a groove surrounding an exposed portion of the first electrode, and the light-emitting layer is formed within the groove.
Accordingly, image quality can be improved by forming a light-emitting layer of uniform thickness through a solution process.

Description

Organic Light Emitting Diode Display Device

The present invention relates to an organic light-emitting diode display device, and more particularly, to a large-area, high-resolution organic light-emitting diode display device capable of providing uniform brightness.

Recently, flat panel displays with excellent characteristics such as thinness, weight reduction, and low power consumption have been widely developed and applied to various fields.

Among flat panel displays, an organic light emitting diode display device (OLED display device), also called an organic electroluminescent display device, is a device that emits light by injecting charges into a light-emitting layer formed between a cathode, which is an electron-injecting electrode, and an anode, which is a hole-injecting electrode, so that electrons and holes form excitons and then radiatively recombine these excitons. Such an organic light emitting diode display device can be formed on a flexible substrate such as plastic, and because it is self-luminous, it has a high contrast ratio, a response time of several microseconds (㎲), so it is easy to implement a moving image, has no limitation on the viewing angle, is stable even at low temperatures, and can be driven at a relatively low voltage of 5 V to 15 V DC, so it has the advantages of easy manufacturing and design of a driving circuit.

The light-emitting layer of an organic light-emitting diode display device is formed by a vacuum thermal evaporation method that selectively deposits an organic light-emitting material using a fine metal mask.

However, this deposition process increases manufacturing costs due to mask preparation, etc., and there are problems in applying it to large-area and high-resolution displays due to mask manufacturing deviation, sagging, shadow effect, etc.

To solve this problem, a method of forming a light-emitting layer by a solution process has been proposed. A conventional organic light-emitting diode display device including a light-emitting layer formed by such a solution process will be described with reference to the drawings.

Figure 1 is a cross-sectional view schematically illustrating a conventional organic light-emitting diode display device, showing one pixel area.

As illustrated in Fig. 1, a first electrode (20) is formed in a pixel area on a substrate (10). A bank (30) covering an edge of the first electrode (20) is formed on top of the first electrode (20). The bank (30) includes a lower bank (32) and an upper bank (34) on top of the lower bank (32).

A light-emitting layer (40) is formed on the upper portion of the first electrode (20) surrounded by a bank (30), and a second electrode (50) is formed substantially on the entire surface of the substrate (10) on the upper portion of the light-emitting layer (40) and the bank (30). The first electrode (20), the light-emitting layer (40), and the second electrode (50) form an organic light-emitting diode (D).

Here, the light-emitting layer (40) is formed through a solution process. More specifically, a solution containing an organic light-emitting material is dropped on the first electrode (20) exposed and surrounded by a bank (30), and then dried to form the light-emitting layer (40). At this time, the bank (30) defines the area where the light-emitting layer (40) is to be formed, and prevents the solution dropped on one pixel area from penetrating into an adjacent pixel area.

However, when forming the light-emitting layer (40) by this solution process, since the solvent does not evaporate uniformly during the drying process of the solution, the light-emitting layer (40) formed within the pixel area has a reduced flatness. That is, when the solution dries, the drying speed of the solvent is different at the center and the edge of the pixel area, so that the height of the light-emitting layer (40) increases from the center to the edge of the pixel area. Accordingly, the thickness of the light-emitting layer (40) increases from the center to the edge of the pixel area, and the light-emitting layer (40) is formed in a U shape.

Meanwhile, the light-emitting layer (40) has a multi-layer structure to increase light-emitting efficiency, and the flatness decreases more severely as it is laminated.

Figure 2 is a drawing schematically illustrating the profile of a light-emitting layer in a conventional organic light-emitting diode display device.

As illustrated in FIG. 2, the emitting layer (40 in FIG. 1) includes a hole injecting layer (HIL), a hole transporting layer (HTL), and an emitting material layer (EML) that are sequentially laminated, and each of the hole injection layer (HIL), the hole transporting layer (HTL), and the emitting material layer (EML) is formed through a solution process. Here, the reference numeral BK1 indicates the first bank.

At this time, the height of the hole injection layer (HIL) is higher at the edge than at the center of the pixel area, and the flatness of the film deteriorates as it goes toward the hole transport layer (HTL) and the light emitting material layer (EML) due to the hole injection layer (HIL). Accordingly, the thickness of the film becomes uneven, and the point where the flatness deteriorates tends to move toward the center of the pixel area.

Organic light-emitting diodes having light-emitting layers of such uneven thickness do not emit light uniformly, and accordingly, the brightness of the display device of the organic light-emitting diode becomes uneven, resulting in a deterioration in image quality.

In order to solve the above problems, the present invention aims to solve the problems of increased manufacturing cost and area and resolution limitations of an organic light-emitting diode display device by a deposition process.

In addition, the present invention seeks to solve the problem of brightness uniformity of an organic light-emitting diode display device.

In order to achieve the above object, an organic light-emitting diode display device according to the present invention includes a substrate, a first electrode positioned in a pixel area on the substrate, a bank covering an edge of the first electrode and exposing the first electrode, a light-emitting layer on the first electrode within the pixel area, and a second electrode on the light-emitting layer, wherein the bank includes a first bank and a second bank on the first bank, the first bank includes a protrusion protruding into the pixel area from a side surface of the second bank, the protrusion of the first bank has a groove surrounding an exposed portion of the first electrode, and the light-emitting layer is formed within the groove.

At this time, the home surrounds the side of the first electrode and can expose the upper surface of the protective film under the first electrode.

Alternatively, the home may be located above the first electrode.

One side of the home may coincide with the side of the second bank.

Here, the first bank may be hydrophilic and the second bank may be hydrophobic.

In the present invention, by forming the light-emitting layer of an organic light-emitting diode by a solution process, the manufacturing cost is reduced and a large-area and high-resolution organic light-emitting diode display device can be provided.

In addition, by forming a groove in the first bank of the bank including the first bank and the second bank so that a light-emitting layer is formed within the groove of the first bank, the flatness of the light-emitting layer can be improved to form a thin film having a uniform thickness. Accordingly, the image quality can be improved.

In addition, it is possible to prevent increased power consumption and reduced lifespan caused by a light-emitting layer of uneven thickness.

Figure 1 is a cross-sectional view schematically illustrating a conventional organic light-emitting diode display device, showing one pixel area.
Figure 2 is a drawing schematically illustrating the profile of a light-emitting layer in a conventional organic light-emitting diode display device.
FIG. 3 is a circuit diagram showing one pixel area of an organic light-emitting diode display device according to an embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view of an organic light-emitting diode display device according to a first embodiment of the present invention.
FIG. 5 is a schematic plan view of an organic light-emitting diode display device according to the first embodiment of the present invention.
FIG. 6 is a drawing schematically illustrating the profile of a light-emitting layer in an organic light-emitting diode display device according to the first embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view of an organic light-emitting diode display device according to a second embodiment of the present invention.

An organic light emitting diode display device according to the present invention comprises: a substrate; a protective film on the substrate; a first electrode positioned in a pixel area on the protective film; a bank covering an edge of the first electrode and exposing the first electrode; an emission layer on the first electrode within the pixel area; and a second electrode on the emission layer, wherein the bank comprises a first bank and a second bank on the first bank, the first bank includes a protrusion protruding from a side surface of the second bank into the pixel area, and the protrusion of the first bank has a groove surrounding an exposed portion of the first electrode.

The above home is spaced apart from the first electrode.

The above groove surrounds a side surface of the first electrode.

The above groove exposes the upper surface of the protective film.

The above home is located above the first electrode.

One side of the above home coincides with the side of the second bank.

The above-mentioned light-emitting layer is also formed within the groove.

The light-emitting layer within the above groove is in contact with the protective film.

The first bank is hydrophilic and the second bank is hydrophobic.

Hereinafter, an organic light-emitting diode display device according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a circuit diagram showing one pixel area of an organic light-emitting diode display device according to an embodiment of the present invention.

As illustrated in FIG. 3, an organic light-emitting diode display device according to an embodiment of the present invention includes gate lines (GL) and data lines (DL) that intersect each other to define pixel areas (P), and in each pixel area (P), a switching thin film transistor (Ts), a driving thin film transistor (Td), a storage capacitor (Cst), and an organic light-emitting diode (D) are formed.

In more detail, the gate electrode of the switching thin film transistor (Ts) is connected to the gate wiring (GL), and the source electrode is connected to the data wiring (DL). The gate electrode of the driving thin film transistor (Td) is connected to the drain electrode of the switching thin film transistor (Ts), and the source electrode is connected to a high potential voltage (VDD). The anode of the organic light emitting diode (D) is connected to the drain electrode of the driving thin film transistor (Td), and the cathode is connected to a low potential voltage (VSS). The storage capacitor (Cst) is connected to the gate electrode and the drain electrode of the driving thin film transistor (Td).

Looking at the image display operation of such an organic light-emitting diode display device, a switching thin film transistor (Ts) is turned on in accordance with a gate signal applied through a gate wiring (GL), and at this time, a data signal applied through a data wiring (DL) is applied to the gate electrode of a driving thin film transistor (Td) and one electrode of a storage capacitor (Cst) through the switching thin film transistor (Ts).

The driving thin film transistor (Td) is turned on according to a data signal and controls the current flowing through the organic light emitting diode (D) to display an image. The organic light emitting diode (D) emits light according to the current of the high potential voltage (VDD) transmitted through the driving thin film transistor (Td).

That is, since the amount of current flowing through the organic light-emitting diode (D) is proportional to the size of the data signal, and the intensity of light emitted by the organic light-emitting diode (D) is proportional to the amount of current flowing through the organic light-emitting diode (D), the pixel area (P) displays different gradations depending on the size of the data signal, and as a result, the organic light-emitting diode display device displays an image.

The storage capacitor (Cst) maintains a charge corresponding to a data signal for one frame, thereby keeping the amount of current flowing through the organic light-emitting diode (D) constant and maintaining the gradation displayed by the organic light-emitting diode (D) constant.

-Example 1-

FIG. 4 is a schematic cross-sectional view of an organic light-emitting diode display device according to a first embodiment of the present invention, and FIG. 5 is a schematic plan view of an organic light-emitting diode display device according to the first embodiment of the present invention, showing one pixel area. For convenience, only a bank and a first electrode are shown in FIG. 5.

As shown in FIGS. 4 and 5, a patterned semiconductor layer (122) is formed on an insulating substrate (110). The substrate (110) may be a glass substrate or a flexible substrate made of a polymer such as polyimide.

The semiconductor layer (122) may be formed of an oxide semiconductor material, in which case a light-shielding pattern (not shown) and a buffer layer (not shown) may be formed under the semiconductor layer (122), and the light-shielding pattern blocks light incident on the semiconductor layer (122) to prevent the semiconductor layer (122) from being deteriorated by light. The buffer layer may be formed of an inorganic insulating material such as silicon oxide or silicon nitride. Alternatively, the semiconductor layer (122) may be formed of polycrystalline silicon, in which case a buffer layer (not shown) may be formed between the substrate (110) and the semiconductor layer (122). In addition, both edges of the semiconductor layer (122) formed of polycrystalline silicon may be doped with impurities.

On top of the semiconductor layer (122), a gate insulating film (130) made of an insulating material is formed substantially on the entire surface of the substrate (110). The gate insulating film (130) may be formed of an inorganic insulating material such as silicon oxide (SiO2). When the semiconductor layer (122) is made of polycrystalline silicon, the gate insulating film (130) may be formed of silicon oxide (SiO2) or silicon nitride (SiNx).

A gate electrode (132) made of a conductive material such as metal is formed on the upper portion of the gate insulating film (130) corresponding to the center of the semiconductor layer (122). In addition, a gate wiring (not shown) and a first capacitor electrode (not shown) may be formed on the upper portion of the gate insulating film (130). The gate wiring extends along one direction, and the first capacitor electrode is connected to the gate electrode (132).

Meanwhile, in the embodiment of the present invention, the gate insulating film (130) is formed on the entire surface of the substrate (110), but the gate insulating film (130) may be patterned in the same shape as the gate electrode (132).

An interlayer insulating film (140) made of an insulating material is formed on the entire surface of the substrate (110) above the gate electrode (132). The interlayer insulating film (140) may be formed of an inorganic insulating material such as silicon oxide (SiO2) or silicon nitride (SiNx), or may be formed of an organic insulating material such as photo acryl or benzocyclobutene.

The interlayer insulating film (140) has first and second contact holes (140a, 140b) that expose upper surfaces on both sides of the semiconductor layer (122). The first and second contact holes (140a, 140b) are positioned on both sides of the gate electrode (132) and spaced apart from the gate electrode (132). Here, the first and second contact holes (140a, 140b) are also formed within the gate insulating film (130). In contrast, when the gate insulating film (130) is patterned in the same shape as the gate electrode (132), the first and second contact holes (140a, 140b) are formed only within the interlayer insulating film (140).

Source and drain electrodes (152, 154) are formed of a conductive material such as metal on the upper portion of the interlayer insulating film (140). In addition, data wiring (not shown), power wiring (not shown), and a second capacitor electrode (not shown) may be formed on the upper portion of the interlayer insulating film (140).

The source and drain electrodes (152, 154) are positioned spaced apart from the gate electrode (132) and contact both sides of the semiconductor layer (122) through the first and second contact holes (140a, 140b), respectively. Although not shown, the data wiring extends in a direction perpendicular to the gate wiring and intersects with the gate wiring to define a pixel area, and the power wiring for supplying a high potential voltage is positioned spaced apart from the data wiring. The second capacitor electrode is connected to the drain electrode (154) and overlaps the first capacitor electrode to form a storage capacitor using an interlayer insulating film (140) therebetween as a dielectric.

Meanwhile, the semiconductor layer (122), the gate electrode (132), and the source and drain electrodes (152, 154) form a thin film transistor. Here, the thin film transistor has a coplanar structure in which the gate electrode (132) and the source and drain electrodes (152, 154) are positioned on one side of the semiconductor layer (122), that is, on the upper side of the semiconductor layer (122).

Alternatively, the thin film transistor may have an inverted staggered structure in which the gate electrode is positioned below the semiconductor layer and the source and drain electrodes are positioned above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Here, the thin film transistor corresponds to a driving thin film transistor of an organic light emitting diode display, and a switching thin film transistor (not shown) having the same structure as the driving thin film transistor is further formed on the substrate (110). The gate electrode (132) of the driving thin film transistor is connected to the drain electrode (not shown) of the switching thin film transistor, and the source electrode (152) of the driving thin film transistor is connected to a power wiring (not shown). In addition, the gate electrode (not shown) and the source electrode (not shown) of the switching thin film transistor are connected to the gate wiring and the data wiring, respectively.

A protective film (160) made of an insulating material is substantially formed on the entire surface of the substrate (110) above the source and drain electrodes (152, 154). The protective film (160) may be formed of an organic insulating material such as benzocyclobutene or photoacrylic. Meanwhile, an inorganic insulating film made of an inorganic insulating material such as silicon oxide (SiO2) or silicon nitride (SiNx) may be further formed below the protective film (160).

The protective film (160) has a drain contact hole (160a) that exposes the drain electrode (154). Here, the drain contact hole (160a) is illustrated as being formed spaced apart from the second contact hole (140b), but the drain contact hole (160a) may be formed directly above the second contact hole (140b).

A first electrode (162) is formed of a conductive material having a relatively high work function in the pixel region on the upper portion of the protective film (160). The first electrode (162) contacts the drain electrode (154) through the drain contact hole (160a). For example, the first electrode (162) may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

A bank (170) is formed with an insulating material on top of the first electrode (162). The bank (170) is positioned between adjacent pixel areas, has a penetration hole (170a) that exposes the first electrode (162), and covers the edge of the first electrode (162).

The bank (170) includes a first bank (172) and a second bank (174) above the first bank (172). Here, the width of the second bank (174) is narrower than the width of the first bank (172), so that the first bank (172) includes a protrusion that protrudes from the side of the second bank (174) into the pixel area. In addition, the protrusion of the first bank (172) has a groove (172a) that surrounds an exposed portion of the first electrode (162).

In more detail, the groove (172a) is spaced apart from the first electrode (162) and surrounds the side surface of the first electrode (162). If the groove (172a) is not spaced apart from the first electrode (162) and surrounds the side surface of the first electrode (162), the groove (172a) exposes the first electrode (162), which causes a problem in that light emission occurs in an undesired area.

The depth of the groove (172a) is the same as the thickness of the first bank (172), so that the groove (172a) can expose the upper surface of the protective film (160) located below the first bank (172). Alternatively, the depth of the groove (172a) can be smaller than the thickness of the first bank (172). Alternatively, the depth of the groove (172a) can be larger than the thickness of the first bank (172), so that the groove (172a) can be formed to extend into the protective film (160).

Additionally, one side of the home (172a) may coincide with a side of the second bank (174). Alternatively, one side of the home (172a) may be spaced apart from the side of the second bank (174).

Here, it is preferable that the penetration hole (170a) exposing the first electrode (160) and the groove (172a) surrounding the exposed portion of the first electrode (160) have the same shape. In FIG. 5, the penetration hole (170a) and the groove (172a) are illustrated as having a rectangular shape, but the shapes of the penetration hole (170a) and the groove (172a) may be changed. For example, the corners of the penetration hole (170a) and the groove (172a) may be formed as curved surfaces. Alternatively, the penetration hole (170a) and the groove (172a) may have a substantially long circular shape having a major axis and a minor axis, or may have a polygonal shape, but are not limited thereto.

Meanwhile, the cross-section of the groove (172a) is illustrated as having a square shape, but the cross-section shape of the groove (172a) is not limited thereto and may be changed. For example, the cross-section shape of the groove (172a) may be a triangle or a semicircle.

The first bank (172) is made of a material having relatively high surface energy to lower the contact angle with the light-emitting layer material formed later, and the second bank (174) is made of a material having relatively low surface energy to increase the contact angle with the light-emitting layer material formed later, thereby preventing the light-emitting layer material from overflowing into the adjacent pixel area. Therefore, the surface energy of the first bank (172) is higher than the surface energy of the second bank (174). For example, the first bank (172) may be made of an inorganic insulating material or an organic insulating material having hydrophilic characteristics, and the second bank (174) may be made of an organic insulating material having hydrophobic characteristics.

Alternatively, the first bank (172) and the second bank (174) may be an integral structure made of the same material, and in this case, the first bank (172) and the second bank (174) may be made of an organic insulating material having hydrophobic properties.

A light-emitting layer (180) is formed on the upper portion of the first electrode (162) exposed through the penetration hole (170a) of the bank (170). This light-emitting layer (180) can be formed through a solution process. As the solution process, a printing method or a coating method using a spray device including a plurality of nozzles can be used, but is not limited thereto. As an example, an inkjet printing method can be used as the solution process.

Here, the light-emitting layer (180) is also formed within the groove (172a) of the first bank (172), and the height of the light-emitting layer (180) is lowered at the edge of the pixel area, thereby improving the flatness of the film. This will be described in detail later.

Although not illustrated, the light-emitting layer (180) may include a hole auxiliary layer, an emitting material layer (EML), and an electron auxiliary layer sequentially laminated from above the first electrode (162). The hole auxiliary layer may include at least one of a hole injecting layer (HIL) and a hole transporting layer (HTL), and the electron auxiliary layer may include at least one of an electron transporting layer (ETL) and an electron injecting layer (EIL).

Here, the hole-assisting layer and the light-emitting material layer are formed only within the transmission hole (170a), and the electron-assisting layer can be formed substantially on the entire surface of the substrate (110). In this case, the hole-assisting layer and the light-emitting material layer can be formed through a solution process, and the electron-assisting layer can be formed through a vacuum deposition process.

A second electrode (192) is formed substantially on the entire surface of the substrate (110) on top of the light-emitting layer (180) using a conductive material having a relatively low work function. Here, the second electrode (192) may be formed of aluminum, magnesium, silver, or an alloy thereof.

The first electrode (162), the light-emitting layer (180), and the second electrode (192) form an organic light-emitting diode (D), with the first electrode (162) acting as an anode and the second electrode (192) acting as a cathode.

Although not shown, an encapsulation film (not shown) may be formed on the second electrode (192) to prevent external moisture from penetrating into the organic light-emitting diode (D). For example, the encapsulation film may have a laminated structure of a first inorganic insulating layer, an organic insulating layer, and a second inorganic insulating layer, but is not limited thereto.

Here, the organic light-emitting diode display device according to the embodiment of the present invention may be a top emission type in which light emitted from the light-emitting layer (180) is output to the outside through the second electrode (192). At this time, the first electrode (162) further includes a reflective layer (not shown) made of an opaque conductive material. For example, the reflective layer may be formed of an aluminum-palladium-copper (APC) alloy, and the first electrode (162) may have a triple-layer structure of ITO/APC/ITO. In addition, the second electrode (192) may have a relatively thin thickness so that light may be transmitted, and the light transmittance of the second electrode (192) may be about 45-50%.

In contrast, the organic light-emitting diode display device according to an embodiment of the present invention may be a bottom emission type in which light emitted from the light-emitting layer (180) is output to the outside through the first electrode (162).

FIG. 6 is a drawing schematically illustrating the profile of a light-emitting layer in an organic light-emitting diode display device according to the first embodiment of the present invention.

As illustrated in FIG. 6, the light-emitting layer (180 in FIG. 4) includes a hole injection layer (HIL), a hole transport layer (HTL), and a light-emitting material layer (EML) that are sequentially laminated, and each of the hole injection layer (HIL), the hole transport layer (HTL), and the light-emitting material layer (EML) is formed through a solution process.

At this time, since the first bank (BK1) at the edge of the pixel area has a groove (172a in FIG. 4), and the hole injection layer (HIL) is also formed within the groove (172a in FIG. 4) of the first bank (BK1), the height of the hole injection layer (HIL) at the edge of the pixel area becomes lower than before. Accordingly, the flatness of the hole injection layer (HIL) is improved, and the flatness of the hole transport layer (HTL) and the light-emitting material layer (EML) laminated on the hole injection layer (HIL) is also improved.

Accordingly, a light-emitting layer (180 in Fig. 4) having a uniform thickness can be formed.

-Example 2-

FIG. 7 is a schematic cross-sectional view of an organic light-emitting diode display device according to a second embodiment of the present invention.

As illustrated in Fig. 7, a first electrode (262) is formed of a conductive material having a relatively high work function in a pixel area on a substrate (210). For example, the first electrode (262) may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

Although not shown, a plurality of insulating films, for example, a gate insulating film, an interlayer insulating film, and a protective film, may be formed between the substrate (210) and the first electrode (262).

In addition, a switching thin film transistor, a driving thin film transistor, a storage capacitor, a gate wiring, a data wiring, and a power wiring may be formed between the substrate (210) and the first electrode (262), and the switching thin film transistor and the driving thin film transistor may have the same structure as the thin film transistor illustrated in FIG. 4.

A bank (270) is formed with an insulating material on the upper portion of the first electrode (262). The bank (270) is positioned between adjacent pixel areas, has a penetration hole (270a) that exposes the first electrode (262), and covers the edge of the first electrode (262).

The bank (270) includes a first bank (272) and a second bank (274) above the first bank (272). Here, the width of the second bank (274) is narrower than the width of the first bank (272), so that the first bank (272) includes a protrusion that protrudes from the side of the second bank (274) into the pixel area. In addition, the protrusion of the first bank (272) has a groove (272a) that surrounds an exposed portion of the first electrode (262).

More specifically, the groove (272a) is spaced apart from the first electrode (262) and is located on the upper portion of the first electrode (262). At this time, the depth of the groove (272a) is preferably smaller than the thickness of the protrusion of the first bank (272) so that the first electrode (262) is not exposed by the groove (272a). If the groove (272a) exposes the first electrode (262), there is a problem that light emission occurs in an undesired area.

Additionally, one side of the home (272a) may coincide with a side of the second bank (274). Alternatively, one side of the home (272a) may be spaced apart from the side of the second bank (274).

Here, it is preferable that the penetration hole (270a) exposing the first electrode (260) and the groove (272a) surrounding the exposed portion of the first electrode (260) have the same shape. For example, the penetration hole (270a) and the groove (272a) may be rectangular, or the corners of the penetration hole (270a) and the groove (272a) may be curved. Alternatively, the penetration hole (270a) and the groove (272a) may be substantially an elongated circular shape having a major axis and a minor axis, or may be a polygonal shape, but are not limited thereto.

Meanwhile, the cross-section of the groove (272a) is illustrated as having a square shape, but the cross-section shape of the groove (272a) is not limited thereto and may be changed. For example, the cross-section shape of the groove (272a) may be a triangle or a semicircle.

The first bank (272) is made of a material having relatively high surface energy to lower the contact angle with the light-emitting layer material formed later, and the second bank (274) is made of a material having relatively low surface energy to increase the contact angle with the light-emitting layer material formed later, thereby preventing the light-emitting layer material from overflowing into the adjacent pixel area. Therefore, the surface energy of the first bank (272) is higher than the surface energy of the second bank (274). For example, the first bank (272) may be made of an inorganic insulating material or an organic insulating material having hydrophilic characteristics, and the second bank (274) may be made of an organic insulating material having hydrophobic characteristics.

Alternatively, the first bank (272) and the second bank (274) may be an integral structure made of the same material, and in this case, the first bank (272) and the second bank (274) may be made of an organic insulating material having hydrophobic properties.

Next, a light-emitting layer (280) is formed on the upper portion of the first electrode (262) exposed through the penetration hole (270a) of the bank (270). This light-emitting layer (280) can be formed through a solution process. As the solution process, a printing method or a coating method using a spray device including a plurality of nozzles can be used, but is not limited thereto. For example, an inkjet printing method can be used as the solution process.

Here, the light-emitting layer (280) is also formed within the groove (272a) of the first bank (272), and accordingly, the height of the light-emitting layer (280) at the edge of the pixel area is lowered, thereby improving the flatness of the film.

Although not illustrated, the light-emitting layer (280) may include a hole-assisting layer, an emission material layer (EML), and an electron-assisting layer sequentially stacked from above the first electrode (262). The hole-assisting layer may include at least one of a hole injection layer (HIL) and a hole transport layer (HTL), and the electron-assisting layer may include at least one of an electron transport layer (ETL) and an electron injection layer (EIL).

Here, the hole-assisting layer and the light-emitting material layer are formed only within the transmission hole (270a), and the electron-assisting layer can be formed substantially on the entire surface of the substrate (210). In this case, the hole-assisting layer and the light-emitting material layer can be formed through a solution process, and the electron-assisting layer can be formed through a vacuum deposition process.

A second electrode (292) is formed on the entire surface of the substrate (210) on top of the light-emitting layer (280) using a conductive material having a relatively low work function. Here, the second electrode (292) may be formed of aluminum, magnesium, silver, or an alloy thereof.

In this way, in the organic light-emitting diode display device according to the present invention, since part or all of the light-emitting layer is formed through a solution process that can be applied to a relatively small area, the manufacturing cost can be reduced by reducing the deposition process, and it can also be applied to a large-area and high-resolution display device.

In addition, by forming a groove in the first bank and forming a light-emitting layer within the groove of the first bank, the flatness of the light-emitting layer can be improved, thereby forming a thin film with a uniform thickness. Accordingly, the brightness can be made uniform, thereby improving the image quality.

In addition, it can improve the efficiency, lifespan, driving voltage, and color characteristics of organic light-emitting diodes.

Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the technical spirit and scope of the present invention as set forth in the claims below.

110: Substrate 122: Semiconductor layer
130: Gate insulator 132: Gate electrode
140: Interlayer insulating film 140a, 140b: First and second contact holes
152: Source electrode 154: Drain electrode
160: Shield 160a: Drain contact hole
162: First electrode 170: Bank
170a: Transmission holes 172, 174: First and second banks
172a: Home 180: Light-emitting layer
192: Second electrode D: Organic light-emitting diode

Claims (10)

substrate and;
A protective film on the above substrate;
A first electrode positioned in a pixel area on the above protective film;
A bank covering an edge of the first electrode and exposing the first electrode;
A light-emitting layer on the upper part of the first electrode within the pixel area;
Second electrode on top of the above light-emitting layer
Including,
The above bank includes a first bank and a second bank above the first bank,
The first bank includes a protrusion protruding from the side of the second bank into the pixel area,
The protrusion of the first bank has a groove surrounding the exposed portion of the first electrode,
The groove is spaced apart from the first electrode and is located above the first electrode, and the depth of the groove is smaller than the thickness of the protrusion of the first bank so that the first electrode is not exposed by the groove.
An organic light-emitting diode display device, wherein the light-emitting layer includes a first portion above the exposed portion of the first electrode and a second portion formed within the groove, and the height of the second portion from the substrate is equal to or less than the height of the first portion.
In the first paragraph,
An organic light-emitting diode display device in which the second part of the light-emitting layer formed within the groove is spaced apart from the first electrode.
In the first paragraph,
An organic light-emitting diode display device wherein the first electrode overlaps the second bank.
delete delete In the first paragraph,
An organic light-emitting diode display device, wherein one side of the above home matches the side of the second bank.
In the first paragraph,
An organic light-emitting diode display device wherein the minimum width of the groove is greater than the maximum depth of the groove.
delete In any one of paragraphs 1, 2, 3, 6, and 7,
An organic light-emitting diode display device, wherein the first bank is made of an organic insulating material having hydrophilic characteristics, and the second bank is made of an organic insulating material having hydrophobic characteristics.
In the first paragraph,
The above light-emitting layer comprises a hole injection layer, a hole transport layer, and a light-emitting material layer that are sequentially laminated,
An organic light-emitting diode display device wherein the heights of the hole injection layer, the hole transport layer and the light-emitting material layer above the exposed portion of the first electrode are equal to or smaller than the heights of the hole injection layer, the hole transport layer and the light-emitting material layer formed within the groove, respectively.

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