KR102249192B1 - Organic light emitting diode display device and fabricating method thereof - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic light emitting diode display device.
The method of manufacturing an organic light emitting diode display device according to the present invention includes forming a first electrode for each subpixel in the display area on a substrate, forming a hole injection layer on the entire surface of the display area on the first electrode, and , Forming a first hole transport layer on the entire surface of the display area on the hole injection layer, and forming a film using a red-green shadow mask having openings corresponding to each of the adjacent red and green subpixels on the first hole transport layer. Simultaneously forming a second hole transport layer having the same thickness on each of the red and green subpixels, and blue on the first and second hole transport layers respectively corresponding to the blue, green, and red subpixels. , Forming a light emitting material layer emitting green and red light, forming an electron transport layer on the entire display area on the light emitting material layer, and forming a second electrode on the entire display area on the electron transport layer. Includes.

Description

Organic light emitting diode display and manufacturing method thereof {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE AND FABRICATING METHOD THEREOF}

The present invention relates to an improved organic light-emitting diode display device and a method of manufacturing the same.

Recently, in the era of full-scale information, the field of display that visually expresses electrical information signals has rapidly developed, and a liquid crystal display device (LCD) with excellent performance of thinner, lighter, and low power consumption, and organic light-emitting diodes. A display device such as an organic light emitting diode (OLED) display device has been developed and is widely used.

Among these display devices, the organic light-emitting diode display device has the advantage of being able to implement a light-weight and thin-type, compared to a liquid crystal display device that requires a separate light source, a backlight unit, by using a self-luminous device.

In addition, the organic light-emitting diode display device has an advantage in that it is easier to manufacture and design a driving circuit because it has a comparatively superior viewing angle and contrast ratio compared to a liquid crystal display device, has a fast response speed, consumes low power consumption, and can drive a direct current low voltage.

In addition, since the internal components are solid, they are resistant to external impact and have a wide range of operating temperatures.

Such an organic light-emitting diode display device includes a display panel including an organic light-emitting layer made of an organic light-emitting material for self-emission and an organic light-emitting diode made of first and second electrodes for emitting the organic light-emitting layer.

Accordingly, in the organic light emitting diode display, when a voltage is applied to the first electrode and the second electrode, electrons and holes respectively injected from the first electrode and the second electrode are combined in the organic light emitting layer to generate excitons, It uses the principle of emitting light while the generated excitons fall from the excited state to the ground state.

This organic light emitting diode display will be described with reference to the drawings.

1 is a plan view illustrating one pixel of a general organic light emitting diode display device.

As shown, in the organic light emitting diode display 1, one pixel P has three subs of red, green, and blue (R, G, B) having a vertically long stripe-shaped slit structure. Pixels SP1, SP2, and SP3 are arranged and configured along the horizontal direction.

These pixels P are repeatedly arranged along rows and columns.

Here, in order to form an organic light emitting layer of a color corresponding to each of red, green, and blue (R, G, B) in the subpixels SP1, SP2, SP3, a shadow mask including an opening and a blocking portion is formed. in need.

To further explain this, first, the shadow mask is aligned on the substrate to form a red organic light emitting layer on the substrate. At this time, the openings are made to correspond to the subpixel areas forming the red organic light emitting layer, and the red subpixel area By arranging the blocking portion to correspond to the area except for the organic material passing through the opening to form a red organic light emitting layer, the organic material is blocked by the blocking portion in the remaining areas. Each of the green organic emission layers and the blue organic emission layers is formed by repeating this method.

Meanwhile, the organic light emitting layer is an example of a plurality of layers rather than a single layer in order to improve luminous efficiency, and may be formed of a hole injection layer, a hole transport layer, a light emitting material layer, and an electron transport layer.

FIG. 2 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in the organic light emitting diode display device of FIG. 1.

As shown, the organic light emitting diode 5 includes a first electrode 11 and a second electrode 35 facing each other, and a plurality of layers between the first electrode 11 and the second electrode 35. It is composed of a composed organic light-emitting layer.

Here, the first electrode 11 is formed for each of the sub-pixels SP1, SP2, and SP3.

The organic light emitting layer has a structure in which a hole injection layer (HIL, 13), a hole transport layer (HTL, 16), a light emitting material layer 24 and an electron transport layer (ETL, 30) are stacked.

In this case, the hole injection layer 13 is formed to have the same thickness over the entire display area.

The hole transport layer 16 has a first hole transport layer 16a formed with the same thickness over the entire display area, and a second and second hole transport layer 16a having different thicknesses corresponding to each of the green and red subpixels SP2 and SP1. It consists of 3 hole transport layers 16b and 16c.

Forming the hole transport layer 16 in this way is because the light emitting material layers 24a, 24b, and 24c emitting each color have different characteristics and different luminous efficiency. This is to implement a microcavity effect that improves light efficiency by forming second and third hole transport layers 16b and 16c having different thicknesses corresponding to the red subpixels SP2 and SP1.

In the organic light emitting diode display device 10 having such a configuration, film formation is performed in the following order.

First, an electron transport layer 13 and a first hole transport layer 16a are sequentially formed over the first electrode 11 by using an open shadow mask having an opening in the entire display area.

Thereafter, a second hole transport layer 16b is formed on the green subpixel SP2 by using a shadow mask for a green subpixel having an opening corresponding to the green subpixel SP2, and the red subpixel SP1 is red. A third hole transport layer 16c is formed on the red subpixel SP1 by using a shadow mask for a red subpixel corresponding to the subpixel SP1 and having an opening.

Next, blue, green, and red subpixels (SP3, SP2, SP1) are formed in the order of blue, green, and red using a shadow mask for a blue subpixel, a shadow mask for a green subpixel, and a shadow mask for a red subpixel. Red light-emitting material layers 24a, 24b, and 24c are formed, respectively.

Then, the electron transport layer 30 and the second electrode 35 are sequentially formed over the blue, green, and red light emitting material layers 24a, 24b, and 24c using an open shadow mask on the entire display area.

In order to form the second electrode 35 from the hole injection layer 13 in this way, 9 mask processes are performed in each of the 9 chambers. There is a problem that occurs. This serves as a cause of failure of the organic light emitting diode 5 and the organic light emitting diode display device.

In addition, as the second and third hole transport layers 16b and 16c are respectively formed in the green and red subpixels SP2 and SP1, the material cost is increasing because the sum of the thicknesses of the material is consumed.

In recent years, organic light-emitting diode displays are being studied to be applied not only to portable computers, but also to desktop computer monitors and wall-mounted televisions. It's going on.

An object of the present invention to solve the above problems is to reduce the number of mask processes by forming a hole transport layer in common in red and green subpixels, to reduce material cost, and to prevent mask defects that may occur during film formation. It is to provide a possible organic light emitting diode display and a method of manufacturing the same.

Another object of the present invention is to provide an organic light emitting diode display device capable of improving the performance of the organic light emitting diode and a method of manufacturing the same.

Through this, there is another object to provide an organic light emitting diode display device having high performance and price competitiveness.

In order to achieve the above object, a method of manufacturing an organic light emitting diode display according to an embodiment of the present invention defines three subpixels each emitting red, green, and blue light as one pixel, and includes a plurality of pixels. A method of manufacturing an organic light emitting diode display device including one display area, the method comprising: forming a first electrode for each subpixel in the display area on a substrate, and forming a hole injection layer on the entire surface of the display area on the first electrode. Forming, forming a first hole transport layer on the entire surface of the display area on the hole injection layer, and a red-green shadow mask having openings corresponding to each of the adjacent red and green subpixels on the first hole transport layer Simultaneously forming a second hole transport layer having the same thickness in each of the red and green subpixels by performing film formation, and the first and second hole transport layers corresponding to each of the blue, green, and red subpixels Forming a light emitting material layer on the light emitting material layer that emits blue, green, and red light, forming an electron transport layer on the entire display area on the light emitting material layer, and a second electrode on the entire display area on the electron transport layer And forming.

Here, each of the red and green subpixels has a horizontally long slit shape and is arranged along a vertical direction, and the blue subpixels have a vertically long slit shape and are disposed on one side of the red and green subpixels. do.

On the other hand, it characterized in that it further comprises the step of forming a capping layer on the second electrode.

In addition, the forming of the electron transport layer includes forming a first electron transport layer corresponding to one of the red, green, and blue subpixels, and a second electron transport layer on the first electron transport layer and the remaining light emitting material layer. It characterized in that it comprises the step of forming a transport layer.

Alternatively, the forming of the electron transport layer may include forming a first electron transport layer over the display area on the light-emitting material layer, and forming a second electron transport layer over the display area over the first electron transport layer. It characterized in that it comprises a.

And before forming the light emitting material layer, it characterized in that it further comprises the step of forming a blocking layer corresponding to the entire display area or one of the red, green, and blue subpixels.

Or, after forming the light emitting material layer, forming a blocking layer corresponding to the entire display area or one of the red, green, and blue subpixels.

Meanwhile, in the organic light emitting diode display according to an exemplary embodiment of the present invention, three subpixels each emitting red, green, and blue light are defined as one pixel, and on a substrate including a display area including a plurality of pixels. A first electrode formed for each subpixel in the display area, a hole injection layer formed on the first electrode over the display area, a first hole transport layer formed over the display area on the hole injection layer, and the first A second hole transport layer formed to have the same thickness in each of the adjacent red and green subpixels on the hole transport layer, and a blue formed corresponding to each of the blue, green, and red subpixels on the first hole transport layer and the second hole transport layer. , A green and red light-emitting material layer, an electron transport layer formed on the entire display area on the light-emitting material layer, and a second electrode formed on the entire display area on the electron transport layer, and each of the red and green subpixels The formed second hole transport layer is characterized in that it is formed of the same material.

Here, each of the red and green subpixels has a horizontally long slit shape and is arranged along a vertical direction, and the blue subpixels have a vertically long slit shape and are disposed on one side of the red and green subpixels. do.

In addition, it characterized in that it further comprises a capping layer formed on the second electrode.

In addition, the electron transport layer is characterized in that it is composed of a first electron transport layer formed corresponding to one of the red, green, and blue subpixels, and a second electron transport layer formed on the first electron transport layer and the remaining light emitting material layer. .

Alternatively, the electron transport layer may include a first electron transport layer and a second electron transport layer sequentially formed over the display area.

In addition, it characterized in that it further comprises a blocking layer formed in contact with the entire blue, green, and red light emitting material layer or a lower surface of one of them.

Or, it characterized in that it further comprises a blocking layer formed in contact with the entire blue, green, red light emitting material layer or an upper surface of one of them.

The first electron transport layer has a first LUMO level, and the second electron transport layer has a second LUMO level smaller than the first LUMO level.

According to the organic light emitting diode display device and its manufacturing method according to the present invention, a mask defect is prevented by applying a pixel structure in a modified structure instead of a conventional slit structure to widen a rip area in the mask.

In addition, by simultaneously forming a hole transport layer on the red and green subpixels, the number of chamber and mask processes can be reduced, and material cost can be reduced.

At this time, by simultaneously forming a hole transport layer on the red and green subpixels, the remaining chamber can be used to form a film for improving the performance of the organic light emitting diode.

1 is a plan view showing one pixel in a general organic light emitting diode display device.
FIG. 2 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in the organic light emitting diode display device of FIG. 1.
3 is a circuit diagram of one pixel of an organic light emitting diode display according to an exemplary embodiment of the present invention.
4 is a schematic cross-sectional view of a part of an organic light emitting diode display device according to an exemplary embodiment of the present invention.
5 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in the organic light emitting diode display according to the first embodiment of the present invention.
6 is a plan view showing one pixel in the OLED display device according to the first embodiment of the present invention.
7 is a view showing masks applied to a manufacturing process of an organic light emitting diode display device according to the first embodiment of the present invention.
8 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in an organic light emitting diode display according to a second embodiment of the present invention.
9 is a graph for explaining a life change according to a cross-sectional structure of an organic light emitting diode according to a second embodiment of the present invention.
10 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in an organic light emitting diode display according to a third embodiment of the present invention.
11A to 11C are graphs for explaining changes in lifespan of red, green, and blue subpixels according to the cross-sectional structure of the organic light emitting diode according to the third embodiment of the present invention. A diagram showing a change in luminance.
12 illustrates red, green, and blue organic light-emitting materials provided in red, green, and blue subpixels, respectively, and LUMOs of first and second electron transport layers in the organic light emitting diode display according to the third embodiment of the present invention. (lowest unoccupied molecular orbital) energy level comparison.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

3 is a circuit diagram of one pixel of an organic light emitting diode display according to an exemplary embodiment of the present invention.

As shown in FIG. 3, a switching thin film transistor STr, a driving thin film transistor DTr, and a storage capacitor StgC are included in one sub-pixel SP of the OLED display device 100. , And an organic light-emitting diode (E).

Here, a gate line GL is formed in the first direction, and a data line DL defining the pixel region P is formed together with the gate line GL in a second direction crossing the first direction. , A power line PL for applying a power voltage is formed, separated from the data line DL.

A switching thin film transistor STr is formed at a portion where the data line DL and the gate line GL intersect, and a driving thin film transistor DTr electrically connected to the switching thin film transistor STr is formed.

The gate electrode of the switching thin film transistor STr is connected to the gate line GL, and the source electrode and the drain electrode are connected to the data line DL and the gate electrode of the driving thin film transistor DTr, respectively.

The switching thin film transistor STr is turned on or off according to the scan signal applied from the gate line GL, and when turned on, the data signal applied through the data line DL is transmitted. Print it out.

The source electrode and the drain electrode of the driving thin film transistor DTr are connected to the power wiring PL for applying a power voltage and the organic light emitting diode E, respectively. At this time, the storage capacitor StgC is connected between the gate electrode and the source electrode of the driving thin film transistor DTr.

The storage capacitor StgC temporarily stores a data signal applied through the data line DL when the switching thin film transistor STr is turned on, and provides the temporarily stored data signal to the driving thin film transistor DTr when the switching thin film transistor STr is turned off.

Accordingly, when a signal is applied through the gate line GL, the switching thin film transistor STr is turned on, and the signal of the data line DL is transmitted to the gate electrode of the driving thin film transistor DTr, thereby Since the transistor DTr is turned on, light is output through the organic light emitting diode E. At this time, when the driving thin film transistor DTr is turned on, the level of the current flowing from the power wiring PL to the organic light emitting diode E is determined. gray scale), and the storage capacitor (StgC) serves to keep the gate voltage of the driving thin film transistor (DTr) constant when the switching thin film transistor (STr) is off. Even if STr) is turned off, the level of the current flowing through the organic light emitting diode E can be kept constant until the next frame.

4 is a schematic cross-sectional view of a part of an organic light emitting diode display device according to a first embodiment of the present invention.

As shown in FIG. 4, in the organic light emitting diode display device 100, first and second substrates 110 and 170 are disposed to face each other.

Here, the first and second substrates 110 and 170 may be divided into a display area AA for displaying an image and a non-display area (not shown) formed along the edge of the display area AA.

In the display area AA on the first substrate 110, a plurality of subpixels SP1 and SP2 are formed by a gate line (not shown) and a data line (not shown) formed along a first direction and a second direction perpendicular thereto. , SP3) are distinguished. In addition, a power wiring (not shown) is formed parallel to the data wiring (not shown).

A switching and driving thin film transistor (not shown, DTr) is formed in each of the plurality of subpixels SP1, SP2, and SP3, and a first electrode 147 connected to the driving thin film transistor DTr is formed.

In addition, a red, green, and blue organic emission layer 155 that emits red, green, and blue light is formed on the first electrode 147 in correspondence to each subpixel, and a second electrode ( 158) is formed. At this time, the first electrode 147, the organic light emitting layer 155, and the second electrode 158 sequentially stacked on each subpixel form the organic light emitting diode 105.

In response to the first substrate 110 having such a structure, the second substrate 170 for encapsulation faces, and a seal pattern formed on the inner non-display area of the first or second substrates 110 and 170 The first substrate 110 and the second substrate 170 are bonded together by (not shown).

On the other hand, in the embodiment of the present invention, the second substrate 170 is provided to perform encapsulation of the organic light emitting diode 105, but instead of the second substrate 170, the upper portion of the organic light emitting diode 105 A transparent film (not shown) is attached to the film, or an encapsulation ray line film (not shown) made of an organic material or an inorganic material is formed, so that these components can perform encapsulation of the organic light-emitting diode E.

Hereinafter, red, green, and blue subpixels and cross-sectional structures in the display area AA of the organic light emitting diode display device 100 having the above-described configuration will be described with reference to the drawings.

FIG. 5 is a simplified diagram illustrating a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in the organic light emitting diode display device according to the first embodiment of the present invention. A diagram for explaining the structure of a shadow mask applied to a manufacturing process of an organic light emitting diode display device.

The organic light-emitting diode 105 of the organic light-emitting diode display device according to the first embodiment of the present invention includes a first electrode 147 and a second electrode 158 facing each other, and a first electrode as shown in FIG. 5. It includes an organic light emitting layer 155 composed of a plurality of layers between the electrode 147 and the second electrode 158. In this case, a capping layer (CPL) 159 formed on the second electrode 158 may be further included.

Here, the first electrodes 147 are shown as being connected to each other, but are substantially divided and formed for each of the sub-pixels SP1, SP2, and SP3.

The first electrode 147 has a double-layer structure of a first layer made of a metal material having excellent reflectivity and a second layer made of a transparent conductive material having a high work function value, or a first layer made of a transparent conductive material. It may be formed of a triple-layer structure of a second layer made of a metal material having excellent hyperreflectivity and a third layer made of a transparent conductive material having a high work function value. At this time, the metal material having excellent reflectivity may be any one of aluminum (Al), aluminum alloy (AlNd), and silver (Ag), and the transparent conductive material is indium-tin-oxide (ITO) or indium-zinc-oxide ( IZO) can be used.

An organic light emitting layer 155 composed of a plurality of layers is formed on the first electrode 147, and the organic light emitting layer 155 includes a hole injection layer (HIL, 148), a hole transport layer (HTL, 149), and a light emitting material. It may include a layer 150 and an electron transport layer (ETL, 152).

Here, the hole transport layer 149 has a first thickness corresponding to the first hole transport layer 149a formed with the same thickness on the entire display area and the adjacent red and green subpixels SP1 and SP2, and has a common thickness. It is characterized by being composed of the formed second hole transport layer (149b). This will be described in more detail later.

A second electrode 158 is formed on the organic emission layer 155 and on the entire display area.

Here, the second electrode 158 is a metal material having a low work function value, for example, aluminum (Al), silver (Ag), magnesium (Mg), magnesium-aluminum alloy (Mg:Al), magnesium-silver (Mg). :Ag) can be formed to have a relatively thin thickness of about 20 Å to 200 Å, so that light can be transmitted.

A capping layer (CPL) 159 may be further formed on the entire display area over the second electrode 158, and the capping layer 159 is an organic layer implemented in an upper emission method according to an embodiment of the present invention. The light emitting diode collects light emitted from the second electrode 158 so that the light has straightness, thereby increasing the light efficiency of the organic light emitting diode.

The capping layer 159 may use an organic material having a relatively large refractive index in the range of 1.8 to 2.0, for example, in order to improve light efficiency.

One pixel P of an organic light emitting diode display device having such a structure is composed of three subpixels SP1, SP2, and SP3 of red, green, and blue (R, G, B) as shown in FIG. 6. The red subpixel (SP1) and the green subpixel (SP2) have a horizontally long slit shape and are arranged along the vertical direction, and the blue subpixel (SP3) has a vertically long slit shape, and the red and green subpixels It is characterized in that it is disposed on one side of (SP1, SP2).

By having such a pixel structure, when the hole transport layer 149 is formed in common for the red and green subpixels SP1 and SP2, the mask rip area is small and the mask may be twisted or twisted. This can be prevented. In more detail, in the pixel structure according to the present invention, unlike the conventional slit structure, since the aperture ratio ratio between the red and green subpixels and the blue subpixel is similar, or the aperture ratio of the blue subpixel is high, a film is formed on the red and green subpixels Even if it proceeds at the same time, the mask defect does not occur because the remaining lip area is large. In particular, it is advantageous to apply the modified structure according to the present invention when implementing the organic light emitting diode display device with high resolution and large screen.

A film formation procedure of the organic light emitting diode display device according to the first embodiment of the present invention having such a configuration will be described with reference to the shadow mask shown in FIG. 7. Here, for convenience of description, each of the shadow masks is illustrated as having a size corresponding to one pixel.

First, the first and second mask processes are performed using an open mask (MK1) having an opening (op) on the entire display area over the first electrode 147 formed for each sub-pixel (SP1, SP2, SP3). Thus, the hole injection layer 148 and the first hole transport layer 149a are sequentially formed.

Thereafter, a third mask process is performed using a shadow mask for red and green sub-pixels (MK2) having two openings (op) corresponding to each of the red and green sub-pixels SP1 and SP2. A second hole transport layer 149b simultaneously formed of the same material is formed on each of (SP1, SP2).

Accordingly, the hole transport layer 149 has a double-layer structure of the first hole transport layer 149a and the second hole transport layer 149b.

Next, in the blue sub-pixel (SP3), a fourth mask process is performed using a shadow mask (MK3) for a blue sub-pixel (MK3) having an opening (op) corresponding to the blue sub-pixel (SP3) over the first hole transport layer 149a. A shadow mask for a green subpixel having an opening op corresponding to the green subpixel SP2 above the second hole transport layer 149b in the green subpixel SP2 by proceeding to form the blue light emitting material layer 150a The green light-emitting material layer 150b is formed by performing the fifth mask process using (MK4), and in the red sub-pixel SP1, the opening corresponding to the red sub-pixel SP1 is above the second hole transport layer 149b. The red light-emitting material layer 150c is formed by performing a sixth mask process using the red sub-pixel shadow mask MK5 having (op). At this time, each of the green and red light-emitting material layers 150b and 150c formed on the second hole transport layer 149b are formed to have different thicknesses, and the red light-emitting material layer 150c is formed thicker than the green light-emitting material layer 150b. Can be.

Next, the electron transport layer 152 is formed by performing a seventh mask process using an open mask (MK1) having an opening (op) on the entire display area over the blue, green, and red light emitting material layers 150a, 150b, 150c. And then proceed with the 8th mask process using an open mask (MK1), for example, a metal material having a low work function value, such as aluminum (Al), silver (Ag), magnesium (Mg), and magnesium-aluminum alloy. The organic light-emitting diode 105 is completed by forming the second electrode 158 having a thickness of about 20 Å to 200 Å in any one of (Mg:Al) and magnesium-silver (Mg:Ag).

Here, the capping layer 159 may be further formed by performing a ninth mask process using an off-mask MK1 having an opening op over the entire display area over the second electrode 158.

By configuring the organic light emitting layer 155 as described above, the thicknesses between the first electrode 147 and the second electrode 158 can be different for each of the blue, green, and red subpixels. In more detail, since the blue, green, and red light-emitting material layers 150a, 150b, and 150c have different characteristics and different luminous efficiency, the distance between the first electrode 147 and the second electrode 158 By varying the thickness of the cavity defined as, it is possible to implement a micro cavity effect that improves light efficiency.

In order to realize the effect of a micro cavity, the longest optical distance of light emitted from a red luminous material is usually required, followed by green and blue luminous materials.

Accordingly, it can be seen that the organic light emitting diode display device (100 in FIG. 4) according to the first embodiment of the present invention satisfies the conditions for implementing a micro-cavity effect.

In addition, the biggest feature of the organic light emitting diode display device (100 in FIG. 4) according to the first embodiment of the present invention is that the hole transport layer 149 for the red and green subpixels SP1 and SP2 is simultaneously formed. And, compared to the method of forming the hole transport layer for each of the green subpixels, less organic material is used, material cost is reduced, and the number of mask processes is reduced. In particular, since the organic material is formed in a vacuum chamber due to the nature of the organic material, a chamber corresponding to each mask process must be provided, and the hole transport layer 149 for the red and green subpixels SP1 and SP2 is provided. As they are formed at the same time, there is an advantage that the number of chambers can be reduced. That is, in order to form the hole injection layer 149 to the second electrode 158, 9 mask processes have been performed in each of the 9 chambers in the prior art, but according to the first embodiment of the present invention, 8 times in each of the 8 chambers. It can be formed through a mask process.

In addition, this is possible because a mask defect that may occur in the mask process is prevented by applying a deformation structure different from the conventional slit structure to the pixel.

Meanwhile, in the organic light emitting diode 105 according to the first embodiment of the present invention having the above-described structure, the number of mask processes is reduced and the number of chambers for the mask process can be reduced. 105) can be added to improve the performance. The additionally formed organic light emitting diode display device is used as the second and third embodiments of the present invention, and will be described below with reference to the drawings.

FIG. 8 is a simplified view showing a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in an organic light emitting diode display according to a second embodiment of the present invention. 2 is a graph for explaining the change in life span according to the cross-sectional structure of the organic light emitting diode according to the embodiment. Here, since the structure except for the electron transport layer is the same as that of FIG. 5, a detailed description of the same configuration will be omitted.

As shown in FIG. 8, the organic light emitting diode 205 of the organic light emitting diode display device includes a first electrode 247 and a second electrode 258 facing each other, and a first electrode 247 and a second electrode ( It includes an organic light emitting layer 255 composed of a plurality of layers between the 258.

Here, the organic light emitting layer 255 is composed of a hole injection layer 248, a hole transport layer 249, a light emitting material layer 250, and an electron transport layer 252, wherein the electron transport layer 252 is a first electron transport layer 252a ) And a second electron transport layer 252b to extend the life of the organic light emitting diode 205. In this case, as shown in FIG. 8, the electron transport layer 252 in the green subpixel SP2 includes first and second electron transport layers 252a and 252b, and the light emitting material layer of the red subpixel SP1 ( The thickness of 250c) is larger than the sum of the thickness of the light emitting material layer 250b of the green subpixel SP2 and the thickness of the first electron transport layer 252a.

As in FIG. 5, the hole injection layer 248, the hole transport layer 249 composed of the first and second hole transport layers 249a and 249b, and light emission are performed by performing each of the first to six mask processes using each mask. The material layer 250 is sequentially formed.

Next, in the green subpixel SP2, the first electron transport layer 252a is formed by performing a seventh mask process on the green light emitting material layer 250b using a shadow mask for a green subpixel.

In addition, in the red, green, and blue subpixels (SP1, SP2, SP3), the second electron transport layer 252b is formed on the entire display area by performing an eighth mask process using an open mask. By performing the ninth mask process, the second electrode 258 is formed on the entire surface of the display area to complete the organic light emitting diode display.

In this way, when the electron transport layer 252 is formed in a double-layer structure, there is an advantage in that the driving voltage is reduced and the lifespan of the organic light emitting diode 205 is increased.

This will be described with reference to FIG. 9 and Table 1.

Here, the first embodiment is the structure of the organic light emitting diode of the organic light emitting diode display device according to the first embodiment of FIG. 5, and the second embodiment is the structure of the organic light emitting diode according to the second embodiment of FIG. 8.

Condition volt cd/A life span Green Example 1 4.1 101.2 225hr Example 2 4.3 105.0 410hr

9 and Table 1, there is no significant difference in driving voltage between Example 1 and Example 2, but it was found that Example 2 in which the electron transport layer has a double-layer structure has an 82% increase in lifetime compared to Example 1. I can. That is, it is possible to increase the lifespan by improving the green performance through the electron transport layer.

Meanwhile, referring to FIG. 8, the drawing shows that the first electron transport layer 252a is formed corresponding to the green subpixel SP2, but is not limited thereto, and the first electron transport layer is formed corresponding to the red or green subpixel. In addition, the first electron transport layer may be formed in the entire display area corresponding to the red, green, and blue subpixels.

On the other hand, it is possible to improve the performance of the organic light emitting diode by forming a layer other than the electron transport layer or forming a structure of another layer in a double layer structure.

For example, a first blocking layer is formed between the first electrode 247 and the light-emitting material layer 250 so as to be in contact with the light-emitting material layer 250, or between the second electrode 258 and the light-emitting material layer 250. A second blocking layer may be formed in contact with the light emitting material layer 250. Here, the first blocking layer may serve as an electron blocking layer (EBL) preventing electrons introduced from the second electrode 258 from being injected toward the hole transport layer 249 through the light-emitting material layer 250, and , The second blocking layer may serve as a hole blocking layer HBL that prevents holes introduced from the first electrode 247 from flowing into the electron transport layer 252 through the light-emitting material layer 250.

Like the first electron transport layer, the first blocking layer or the second blocking layer may be formed corresponding to each of the red, green, and blue subpixels, or the entire display area corresponding to the red, green, and blue subpixels. Can be formed in When the first blocking layer or the second blocking layer is formed in this way, the efficiency of the organic light emitting diode is improved.

The organic light emitting diode display device according to the second embodiment of the present invention having such a structure has an advantage of improving performance without increasing the number of processes of a chamber and a mask.

This is possible by simultaneously forming a hole transport layer for the red and green subpixels. In particular, it is implemented by modifying the pixel structure to prevent mask defects that may occur during the mask process.

10 is a simplified view showing a cross-sectional structure of an organic light emitting diode for red, green, and blue subpixels in the organic light emitting diode display device according to the third embodiment of the present invention, and FIGS. 11A to 11C are A graph for explaining a change in lifetime according to a cross-sectional structure of an organic light emitting diode according to a third embodiment of the present invention, and is a view showing a change in luminance of red, green, and blue subpixels with time. Here, the structure excluding the electron transport layer is the same as the organic light emitting diode display device according to the first embodiment of the present invention disclosed in FIG. 5 or the organic light emitting diode according to the second embodiment of the present invention disclosed in FIG. Detailed description of this will be omitted.

As shown in FIG. 10, the organic light emitting diode 305 of the organic light emitting diode display device includes a first electrode 347 and a second electrode 358 facing each other, and a first electrode 347 and a second electrode ( It includes an organic light emitting layer 355 composed of a plurality of layers between the 358.

Here, the organic light emitting layer 355 is composed of a hole injection layer 348, a hole transport layer 349, a light emitting material layer 350, and an electron transport layer 352.

Meanwhile, as the most characteristic feature of the organic light emitting diode display according to the third embodiment of the present invention, the electron transport layer 352 in each of the red, green, and blue subpixel regions SP1, SP2, and SP3 is the first. It is composed of an electron transport layer 352a and a second electron transport layer 352b, and more precisely, the first and second electron transport layers 352a and 352b are formed to correspond to the entire display area. It is characterized by extending the life of the organic light emitting diode 305.

In this case, the second electron transport layer 352b is made of a material having a smaller electron mobility compared to the first electron transport layer 352a. More precisely, the mobility of electrons in the electron transport layer is proportional to the LUMO level of the first and second electron transport layers 352a and 352b to some extent, so the LUMO level of the first electron transport layer 352a is It is characterized by having a value greater than the LUMO level of the transport layer 352b.

12 illustrates red, green, and blue organic light-emitting materials provided in red, green, and blue subpixels, respectively, and LUMOs of first and second electron transport layers in the organic light emitting diode display according to the third embodiment of the present invention. (lowest unoccupied molecular orbitals) is a diagram comparing the levels.

As shown, when comparing the LUMO levels of the organic light-emitting materials 350c, 350b, and 350a emitting red, green, and blue light and the first and second electron transport layers 352a, 352b, the red, green, and blue light-emitting materials It can be seen that (350c, 350b, 350a) have similar LUMO levels, but due to the characteristics of materials that emit different red, green, and blue colors, these red, green, and blue organic light-emitting materials 350c, 350b, and 350a It can be seen that) does not have the exact same LUMO level value.

In the drawing, the blue organic light-emitting material 350a is red and the LUMO level is the lowest compared to the green organic light-emitting materials 350c and 350b, but this is only an example, and the red or green organic light-emitting material 350c, The LUMO level of 350b) may have a higher value than that of the blue organic light emitting material 350a.

In this case, as the most characteristic configuration in the organic light emitting diode display according to the third embodiment of the present invention, the LUMO of the first electron transport layer 352a formed on the red, green, and blue organic light emitting layer and directly contacts the red, green, and blue organic light emitting layer. The level has an LUMO level smaller than the lowest LUMO level value among the red, green, and blue organic light emitting materials 350c, 350b, and 350a.

In addition, as another characteristic configuration, the LUMO level of the second electron transport layer 352b provided in contact with the upper portion of the first electron transport layer 352a is smaller than the LUMO level of the first electron transport layer 352a. It is characterized by having a level value. At this time, as shown in FIG. 12, the difference between the lowest LUMO level value among the blue, green, and red light emitting material layers 350c, 350b, and 350a and the LUMO level value of the first electron transport layer 352a is the first electron transport layer. It may be smaller than the difference between the LUMO level value of 352a and the LUMO level value of the second electron transport layer 352b.

The first electron transport layer 352a may be formed of Alq ₃ or Bebq ₂ , for example, and the second electron transport layer 352b may be formed of a compound containing Liq. The compound may be an anthracene derivative. That is, the second electron transport layer 352b is characterized in that it is a compound composed of Liq and an anthracene derivative.

In addition, the first and second electron transport layers 352a and 352b are characterized by having a thickness of about 100 to 400 Å, respectively.

A method of manufacturing an organic light emitting diode display device according to a third embodiment of the present invention having such a configuration will be briefly described with reference to FIG. 8.

First, the hole injection layer 348 and the first and second hole transport layers 349a and 349b are formed by performing each of the first to six mask processes using each mask in the same manner as described with reference to FIGS. 5 and 7. The configured hole transport layer 349 and the light emitting material layer 350 are sequentially formed.

Next, by using an open mask (MK1 in Fig. 7) having an opening (op in Fig. 7) over the light emitting material layer formed for each of the sub-pixels (SP1, SP2, SP3) with respect to the entire display area, the seventh mask process is performed. For example, the first electron transport layer 352a is formed _{of Alq 3} or Bebq _{2 and has a first LUMO level value.}

Thereafter, the first LUMO level is made of a compound containing Liq on the first electron transport layer 352a by using an open mask (MK1 of Fig. 7) having an opening (op of Fig. 7) over the entire display area. A second electron transport layer 352b having a second LUMO level value smaller than the value is sequentially formed.

Next, by performing the ninth mask process using the open mask (MK1), metal materials having a low work function value on the entire display area, for example, aluminum (Al), silver (Ag), magnesium (Mg), magnesium- An organic light-emitting diode display according to the third embodiment of the present invention by forming a second electrode 358 having a thickness of about 20 Å to 200 Å of any one of aluminum alloy (Mg:Al) and magnesium-silver (Mg:Ag) Complete the device 300.

In this case, although not shown in the drawing, a capping layer (not shown) may be further provided over the second electrode 358 on the entire display area.

Meanwhile, as described above, for the red, green, and blue subpixels SP1, SP2, and SP3, the electron transport layer 352 is formed in a double layer structure, that is, a first electron transport layer 352a having a first LUMO level and In the case of forming a structure having a second electron transport layer 352b having a second LUMO level smaller than the first LUMO level, there is an advantage of reducing the driving voltage of the organic light emitting diode display device 300 and increasing the lifespan at the same time. have.

This will be described with reference to FIGS. 11A to 11C and Table 2.

11A to 11C are graphs for explaining changes in lifetime of red, green, and blue subpixels according to the cross-sectional structure of the organic light emitting diode display device according to the third embodiment of the present invention. It is a diagram showing the luminance change according to In this case, Embodiment 1 (indicated as 1 ETL in the drawing) relates to the organic light emitting diode display device according to FIG. 5, and in Embodiment 3 (indicated as 2 ETL in the drawing) is based on the third embodiment of the present invention described above. The present invention relates to an organic light emitting diode display device according to the present invention.

Condition volt cd/A life span Red Example 1 4.4 44.0 620hr Example 3 4.8 50.5 1300hr Green Example 1 4.1 112.8 167hr Example 3 4.3 124.6 275hr Blue Example 1 4.2 4.8 158hr Example 3 4.2 5.6 225hr

(Life is measured based on the time until the average luminance reaches 96% of the initial luminance)

Referring to FIGS. 11A to 11C and Table 2, there is no significant difference in the driving voltage (volt) between Example 1 and Example 3, but an example in which the electron transport layer has a double layer structure in red, green, and blue subpixels. It can be seen that the lifespan of 3 is significantly increased compared to Example 1 having a single layer structure.

That is, in the case of a red subpixel, it was found that Example 1 had a lifespan of about 620 hr until the luminance reached 96%, whereas Example 2 had an effect of increasing the life by about 110% by becoming about 1300 hr. I can.

In addition, in the case of green subpixels, it was found that Example 1 had a lifespan of about 167 hr until the luminance reached 96%, whereas Example 2 had an effect of increasing the life by about 65% by becoming about 275 hr. I can.

In addition, in the case of the blue subpixel, it was found that Example 1 had a lifespan of about 158 hr until the luminance reached 96%, whereas Example 2 had an effect of increasing the life by about 42% by becoming about 225 hr. I can.

In view of this, in the organic light emitting diode display according to the third embodiment of the present invention, the first and second hole transport layers are formed for red and green subpixels, and further, the electron transport layer is the first electron having a first LUMO level. By constructing to have a double-layer structure of the transport layer and the second electron transport layer having a second LUMO level smaller than the first LUMO level, red, green, and blue colors do not increase the number of processes of the conventional organic light emitting diode display device ground chamber and mask. It is possible to increase the lifespan while improving the performance of the product.

Other components are the same as those of the organic light emitting diode display device according to the second embodiment of the present invention described above, and thus descriptions thereof will be omitted.

The embodiments of the present invention described above are merely exemplary, and those of ordinary skill in the art to which the present invention pertains can freely modify within the scope of the gist of the present invention. Accordingly, the scope of protection of the present invention includes modifications of the present invention within the scope of the appended claims and equivalents thereto.

105: organic light-emitting diode
147: first electrode
148: hole injection layer
149(149a, 149b): hole transport layer (1st and 2nd hole transport layer)
150 (150a, 150b, 150c): light-emitting material layer (blue, green, blue light-emitting material layer)
152: electron transport layer
158: second electrode

Claims (16)

In a method of manufacturing an organic light emitting diode display device including three subpixels each emitting red, green, and blue light as one pixel, and including a display area including a plurality of pixels,
Forming a first electrode for each subpixel in the display area on a substrate;
Forming a hole injection layer over the display area on the first electrode;
Forming a first hole transport layer over the display area on the hole injection layer;
A second hole transport layer having the same thickness is simultaneously formed in each of the red and green subpixels by performing film formation using a shadow mask having an opening corresponding to each of the adjacent red and green subpixels on the first hole transport layer. And;
Forming a light emitting material layer emitting blue, green, and red light on the first and second hole transport layers, respectively, corresponding to the blue, green, and red subpixels;
Forming an electron transport layer over the display area on the light-emitting material layer;
Forming a second electrode on the entire surface of the display area on the electron transport layer,
The step of forming the electron transport layer,
Forming a first electron transport layer corresponding to the green subpixels excluding the red subpixels and the blue subpixels,
And forming a second electron transport layer on the first electron transport layer, the light-emitting material layer of the red sub-pixel, and the light-emitting material layer of the blue sub-pixel. .
The method of claim 1,
Each of the red and green subpixels has a horizontally long slit shape and is arranged along a vertical direction, and the blue subpixels have a vertically long slit shape and are disposed on one side of the red and green subpixels. Method of manufacturing a light emitting diode display device.
The method of claim 1,
And forming a capping layer on the second electrode.
delete delete The method of claim 1,
Before forming the light-emitting material layer,
And forming a blocking layer corresponding to the entire display area or one of the red, green, and blue subpixels.
The method of claim 1,
After forming the light-emitting material layer,
And forming a blocking layer corresponding to the entire display area or one of the red, green, and blue subpixels.
A first electrode that defines three subpixels each emitting red, green, and blue light as one pixel, and is formed for each subpixel in the display area on the substrate including the display area including a plurality of pixels;
A hole injection layer formed over the display area on the first electrode;
A first hole transport layer formed over the display area on the hole injection layer;
A second hole transport layer formed to have the same thickness in each of the adjacent red and green subpixels on the first hole transport layer;
Blue, green, and red light emitting material layers formed in correspondence with the blue, green, and red subpixels on the first hole transport layer and the second hole transport layer;
An electron transport layer formed over the display area on the light-emitting material layer;
A second electrode formed on the entire surface of the display area on the electron transport layer,
The second hole transport layer formed on each of the red and green subpixels is formed of the same material,
The electron transport layer is composed of a first electron transport layer and a second electron transport layer sequentially formed over the display area,
The first electron transport layer has a first LUMO level, the second electron transport layer has a second LUMO level smaller than the first LUMO level, and has a lowest LUMO level value among the blue, green, and red light emitting material layers. The light emitting material layer has a third LUMO level greater than that of the first electron transport layer,
The organic light emitting diode display device, wherein a difference between the first LUMO level value and the third LUMO level value is smaller than a difference between the first LUMO level value and the second LUMO level value.
The method of claim 8,
Each of the red and green subpixels has a horizontally long slit shape and is arranged along a vertical direction, and the blue subpixels have a vertically long slit shape and are disposed on one side of the red and green subpixels. Light-emitting diode display.
The method of claim 8,
An organic light emitting diode display device, further comprising a capping layer formed on the second electrode.
delete delete The method of claim 8,
And a blocking layer formed in contact with the entire blue, green, and red light emitting material layer or a lower surface of one of them.
The method of claim 8,
And a blocking layer formed in contact with the entire blue, green, and red light emitting material layers or an upper surface of one of them.
delete The method of claim 1,
The method of manufacturing an organic light emitting diode display, wherein the thickness of the light emitting material layer of the red subpixel is greater than the sum of the thickness of the light emitting material layer of the green subpixel and the thickness of the first electron transport layer.

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