KR20170080445A - Organic Light Emitting Diode Display Device - Google Patents

Abstract

The organic light emitting diode display of the present invention comprises a substrate having red, green and blue sub-pixel regions defined therein, a first electrode located in each of the red, green and blue sub-pixel regions, Second and third light emitting layers respectively located on the first, second and third sub-pixel regions, and blue sub-pixel regions, and second electrodes on the first, second and third light emitting layers, Green, and blue color filters, respectively, wherein the first and second light emitting layers include a yellow light emitting material having two emission peaks, and the thickness of the hole assist layer of the first light emitting layer is different from that of the second light emitting layer Is less than the thickness of the hole assist layer.

Description

[0001] The present invention relates to an organic light emitting diode (OLED) display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting diode display, and more particularly to an organic light emitting diode display capable of improving lifetime.

2. Description of the Related Art Flat panel displays having excellent characteristics such as thinning, lightening, and low power consumption have been widely developed and applied to various fields.

Among the flat panel display devices, an organic light emitting diode (OLED) display device, also referred to as an organic electroluminescent display device or organic electroluminescent display device, An electron injecting charge is injected into the light emitting layer formed between the anode which is the injection electrode, and the electron and the hole are paired, and then the light is emitted while disappearing. Such an organic light emitting diode display device can be formed not only on a flexible substrate such as a plastic but also because it has a large contrast ratio and response time of several microseconds since it is a self- And the viewing angle is not limited.

The organic light emitting diode display device can be classified into a passive matrix type and an active matrix type according to a driving method. An active type organic light emitting diode display device capable of low power consumption, fixed size, and large size is widely used in various display devices. .

The organic light emitting diode display device includes a plurality of pixels for displaying various colors, and each pixel includes red, green, and blue sub-pixels. Green, and blue organic light emitting diodes are formed in the red, green, and blue sub-pixel regions, respectively.

Each of the red, green, and blue organic light emitting diodes includes red, green, and blue light-emitting material layers, and the light emitting material layer is formed by using a fine metal mask And is difficult to apply to a large-area and high-resolution display device due to fabrication deviation, deflection, shadow effect, etc. of a mask.

To solve this problem, a method of forming a light emitting material layer by a solution process has been proposed. In the solution process, a bank layer surrounding the pixel region is formed, a nozzle of the injector is scanned in a predetermined direction to drop a light emitting material in a pixel region in the bank layer, and then the light emitting material layer is cured . At this time, the hole injecting layer and the hole transporting layer may also be formed by a solution process.

However, the red, green and blue light emitting materials have properties. Particularly, the efficiency of the red light emitting material is low and the life of the green light emitting material is low, so it is difficult to secure red, green, and blue light emitting materials having uniform lifetime and efficiency, do.

On the other hand, the organic light emitting diode display device has a problem in that the reflection of external light is significant, the luminance of the black state is increased due to reflection of external light, and the contrast ratio is lowered. Therefore, the cost is increased by using at least one polarizing plate for blocking external light reflection.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to solve the problem of degrading the lifetime of an organic light emitting diode display.

The present invention also aims at solving the problem of cost increase of the organic light emitting diode display device.

According to an aspect of the present invention, there is provided an organic light emitting diode display comprising: a substrate having red, green, and blue sub-pixel regions defined therein; a first electrode disposed in each of the red, Second, and third light emitting layers located in the red, green, and blue sub-pixel regions above the first electrode, a second electrode on the first, second, and third light emitting layers, Green, and blue sub-pixels corresponding to the red, green, and blue sub-pixel regions, respectively, and the first and second light emitting layers include yellow light emitting materials having two emission peaks And the thickness of the hole-assist layer of the first light-emitting layer is smaller than the thickness of the hole-assist layer of the second light-emitting layer.

The third light emitting layer includes a blue light emitting material, and the thickness of the hole assist layer of the third light emitting layer is smaller than the thickness of the hole assist layer of the first light emitting layer.

In the present invention, the lifetime of the organic light emitting diode display device can be improved by implementing red light and green light using a yellow light emitting material having a relatively long lifetime, a micro cavity effect, and a color filter.

In addition, since the polarizing plate can be omitted in the organic light emitting diode display device of the present invention, the cost can be reduced.

1 is a circuit diagram of one pixel region of an organic light emitting diode display according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing an organic light emitting diode display device according to an embodiment of the present invention.
3 is a schematic view illustrating red, green and blue sub-pixels of an organic light emitting diode display according to an embodiment of the present invention.
4 is a cross-sectional view schematically illustrating light emitted from an organic light emitting diode display according to an exemplary embodiment of the present invention.
FIG. 5A is a view showing a spectrum of light emitted from an organic light emitting diode in red and green sub-pixel regions of an organic light emitting diode display according to an embodiment of the present invention. FIG. And the spectrum of light output from the red and green sub-pixel regions of the display device.
FIG. 6A is a view showing the CIE x color coordinate according to the thickness of the hole assist layer, FIG. 6B is a diagram showing the CIE y color coordinates according to the thickness of the hole assist layer, FIG. Fig.

The organic light emitting diode display device of the present invention includes a substrate having red, green and blue sub-pixel regions defined therein, a first electrode positioned in each of the red, green and blue sub-pixel regions, First, second and third light emitting layers respectively located in the red, green and blue sub-pixel regions, a second electrode on the first, second and third light emitting layers, and a second electrode on the second electrode, Green, and blue color filters corresponding to red, green, and blue sub-pixel regions, respectively, wherein the first and second light emitting layers include a yellow light emitting material, and the thickness of the first light emitting layer is Is less than the thickness.

The yellow light emitting material has a first emission peak in a wavelength range of 530 nm to 555 nm and a second emission peak in a wavelength range of 590 nm to 620 nm.

The yellow luminescent material was prepared by reacting 4,4'-N, N'-dicarbazole-biphenyl (CBP) with bis [2- (4-tertbutylphenyl) benzothiazolato- N , C 2 '] iridium (acetylactonate) ) 2Ir (acac).

Each of the first and second light emitting layers includes a hole assist layer, a light emitting material layer, and an electron assist layer. The thickness of the hole assist layer of the first light emitting layer is smaller than the thickness of the hole assist layer of the second light emitting layer.

The thickness of the hole-assist layer of the first light-emitting layer is 250 nm to 280 nm, and the thickness of the hole-assist layer of the second light-emitting layer is 310 nm to 330 nm.

The third light emitting layer includes a blue light emitting material, and the thickness of the third light emitting layer is smaller than the thickness of the first light emitting layer.

The third light emitting layer includes a hole assist layer, a light emitting material layer, and an electron assist layer. The thickness of the hole assist layer of the third light emitting layer is smaller than the thickness of the hole assist layer of the first light emitting layer.

The thickness of the hole-assist layer of the third light-emitting layer is 30 nm to 70 nm.

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

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

1, an organic light emitting diode display device according to an embodiment of the present invention includes a gate line GL and a data line DL that define pixel regions P to intersect with each other, A switching thin film transistor Ts, a driving thin film transistor Td, a storage capacitor Cst, and an organic light emitting diode De are formed in the region P.

More specifically, the gate electrode of the switching thin film transistor Ts is connected to the gate wiring GL and the source electrode thereof 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 thereof is connected to the high potential voltage VDD. The anode of the organic light emitting diode De is connected to the drain electrode of the driving thin film transistor Td and the cathode is connected to the 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.

The switching TFTs turn on according to the gate signal applied through the gate line GL and the data line DL is turned on at this time. Is applied to the gate electrode of the driving thin film transistor Td and the one electrode of the storage capacitor Cst through the switching thin film transistor Ts.

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

That is, the amount of current flowing through the organic light emitting diode De is proportional to the size of the data signal, and the intensity of light emitted by the organic light emitting diode De is proportional to the amount of current flowing through the organic light emitting diode De, The region P displays different gradations according to the size of the data signal, and as a result, the organic light emitting diode display displays an image.

The storage capacitor Cst maintains the charge corresponding to the data signal for one frame so that the amount of current flowing through the organic light emitting diode De is kept constant and the gradation displayed by the organic light emitting diode De is maintained constant .

However, the organic light emitting diode display according to the embodiment of the present invention is not limited to the illustrated example, and each pixel region may further include a thin film transistor, a signal line, and / or a capacitor for compensation.

2 is a cross-sectional view schematically showing an organic light emitting diode display device according to an embodiment of the present invention, and shows a structure corresponding to one pixel region.

As shown in FIG. 2, a patterned semiconductor layer 122 is formed on an insulating substrate 110. The substrate 110 may be a glass substrate or a plastic substrate. In this 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 may be formed on the semiconductor layer 122 And prevents the semiconductor layer 122 from being deteriorated by light. Alternatively, the semiconductor layer 122 may be made of polycrystalline silicon. In this case, impurities may be doped on both edges of the semiconductor layer 122.

A gate insulating layer 130 made of an insulating material is formed on the entire surface of the substrate 110 on the semiconductor layer 122. The gate insulating film 130 may be formed of an inorganic insulating material such as silicon oxide (SiO ₂ ). When the semiconductor layer 122 is made of polycrystalline silicon, the gate insulating layer 130 may be formed of silicon oxide (SiO ₂ ) or silicon nitride (SiNx).

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

In the embodiment of the present invention, the gate insulating layer 130 is formed on the entire surface of the substrate 110, but the gate insulating layer 130 may be patterned to have the same shape as the gate electrode 132.

An interlayer insulating layer 140 made of an insulating material is formed on the entire surface of the substrate 110 on the gate electrode 132. The interlayer insulating film 140 may be formed of an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN x) or an organic insulating material such as photo acryl or benzocyclobutene .

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

On the interlayer insulating layer 140, source and drain electrodes 142 and 144 are formed of a conductive material such as a metal. A data line (not shown), a power supply line (not shown), and a second capacitor electrode (not shown) may be formed on the interlayer insulating layer 140 in the second direction.

The source and drain electrodes 142 and 144 are spaced around the gate electrode 132 and contact the two sides of the semiconductor layer 122 through the first and second contact holes 140a and 140b, respectively. Although not shown, the data wiring extends along the second direction and crosses the gate wiring to define each pixel region, and the power wiring for supplying the high potential voltage is located apart from the data wiring. The second capacitor electrode is connected to the drain electrode 144, and overlaps the first capacitor electrode to form a storage capacitor with the dielectric interlayer 140 between the two.

On the other hand, the semiconductor layer 122, the gate electrode 132, and the source and drain electrodes 142 and 144 constitute 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 142 and 144 are located on one side of the semiconductor layer 122, that is, above the semiconductor layer 122.

Alternatively, the thin film transistor may have an inverted staggered structure in which a gate electrode is positioned below the semiconductor layer and source and drain electrodes are located 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 corresponding to each pixel region. 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 142 of the driving thin film transistor is connected to the power supply wiring (not shown). In addition, a gate electrode (not shown) and a source electrode (not shown) of the switching thin film transistor are connected to the gate wiring and the data wiring, respectively.

A first passivation layer 152 and a second passivation layer 154 are sequentially formed on the entire surface of the substrate 110 as insulating materials on the source and drain electrodes 142 and 144. The first passivation layer 152 may be formed of an inorganic insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN x), and the second passivation layer 154 may be formed of an organic insulating material such as photoacryl or benzocyclobutene And the upper surface of the second protective film 154 may be flat.

The first passivation layer 152 and the second passivation layer 154 have drain contact holes 156 exposing the drain electrodes 144. Here, the drain contact hole 156 is formed directly on the second contact hole 140b, but may be formed apart from the second contact hole 140b.

One of the first protective film 152 and the second protective film 154 may be omitted. For example, the first protective film 152 made of an inorganic insulating material may be omitted.

A first electrode 162 is formed on the second protective film 154 with a conductive material having a relatively high work function. The first electrode 162 is formed for each pixel region and contacts the drain electrode 144 through the drain contact hole 156. 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 layer 170 is formed of an insulating material on the first electrode 162. The bank layer 170 is located between adjacent pixel regions and has an opening exposing the first electrode 162 and covers the edge of the first electrode 162. [

Here, the bank layer 170 has a single-layer structure, but is not limited thereto. In one example, the bank layer may have a bilayer structure. That is, the bank layer includes the first bank and the second bank above the first bank, and the width of the first bank may be wider than the width of the second bank. In this case, the first bank may be formed of an inorganic insulating material or an organic insulating material having a hydrophilic property, and the second bank may be formed of an organic insulating material having a hydrophobic property.

A light emitting layer 180 is formed on the first electrode 162 exposed through the opening of the bank layer 170. The light emitting layer 180 includes a hole assistant layer 182, a light-emitting material layer (EML) 184, and an electron assistant layer 186 sequentially positioned from above the first electrode 162.

The hole-assist layer 182, the light-emitting material layer 184 and the electron-assist layer 186 are made of an organic material and can be formed through a solution process. Thus, the process can be simplified and a display device with a large area and high resolution can be provided. As the solution process, a spin coating method, an inkjet printing method, or a screen printing method may be used.

Alternatively, the hole-assist layer 182 and the emissive material layer 184 and the electron-assisted layer 186 may be formed through vacuum deposition.

Alternatively, the hole-assist layer 182 and the light-emitting material layer 184 and the electron-assisted layer 186 may be formed by a combination of a solution process and a vacuum deposition.

The hole assist layer 182 may include at least one of a hole injecting layer (HIL) and a hot transporting layer (HTL), and the electron assist layer 186 may include at least one of an electron injecting layer : EIL) and an electron transporting layer (ETL).

A second electrode 192 is formed on the entire surface of the substrate 110 with a conductive material having a relatively low work function on the electron assist layer 186. Here, the second electrode 192 may be formed of aluminum, magnesium, silver, or an alloy thereof.

The first electrode 162 and the emission layer 180 and the second electrode 192 form an organic light emitting diode De and the first electrode 162 serves as an anode and the second electrode 192 serves as an anode. Serves as a cathode.

Here, the active matrix type organic light emitting diode display device according to the embodiment of the present invention includes a top emission type in which light emitted from the light emitting material layer 184 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. Also, the second electrode 192 may have a relatively thin thickness to transmit light, and the second electrode 192 may have a light transmittance of about 45-50%.

The organic light emitting diode display according to an embodiment of the present invention includes a plurality of pixels, each pixel including red, green, and blue sub-pixels, and the red, green, and blue sub- A transistor and an organic light emitting diode are formed.

At this time, the organic light emitting diodes of the red, green, and blue sub-pixel regions have different device thicknesses. This will be described in more detail with reference to the drawings.

3 is a schematic view illustrating red, green and blue sub-pixels of an organic light emitting diode display according to an embodiment of the present invention.

3, red, green, and blue sub-pixel regions Pr, Pg, and Pb are defined on the substrate 110, and organic light emitting diodes De ). The organic light emitting diode De of each of the sub pixel regions Pr, Pg and Pb includes a first electrode 162, a light emitting layer 180, and a second electrode 192.

The first electrode 162 may be an anode and may be made of a conductive material having a relatively large work function value. The first electrode 162 may include a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). In addition, the first electrode 162 may further include a reflective layer at the bottom.

The first electrode 162 is connected to the red, green, and blue sub-pixel regions Pr, Pg, and Pb, Pg, Pb).

The light emitting layer 180 is disposed on the first electrode 162 of each of the sub pixel regions Pr, Pg and Pb and the light emitting layer 180 is formed on the light emitting layer 184, (186).

Here, the light emitting material layer 184 of the red and green sub pixel regions Pr and Pg includes a yellow light emitting material, the light emitting material layer 184 of the blue sub pixel region Pb includes blue light, Emitting material.

The light emitting material layer 184 may be formed through a soluble process. Alternatively, the light emitting material layer 184 may be formed through a solution process and a deposition process, wherein the light emitting material layer 184 of the red and green sub-pixel regions Pr and Pg is formed through a solution process, The light emitting material layer 184 of the pixel region Pb may be formed through a deposition process.

The hole-assist layer 182 may include a hole injection layer (HIL) and a hole transport layer (HTL). At this time, the hole-assist layer 182 of the red, green, and blue sub-pixel regions Pr, Pg, and Pb have different thicknesses. More specifically, the thickness of the hole assisting layer 182 of the red sub-pixel region Pr is smaller than the thickness of the hole assisting layer 182 of the green sub-pixel region Pg, Is greater than the thickness of layer (182).

The hole assist layer 182 may be formed through a solution process, and the thickness may be adjusted by varying the amount of the solution to be dropped.

On the other hand, the electron assist layer 186 may include an electron transport layer (ETL), and the electron assist layer 186 may further include an electron injection layer on the electron transport layer (ETL). The electron assist layer 186 may be formed through a deposition process.

A second electrode 192, which is a cathode, is positioned above the light emitting layer 180 of each of the sub-pixel regions Pr, Pg, and Pb. The second electrode 192 may be formed of aluminum, magnesium, silver, or an alloy thereof, and the second electrode 192 may have a relatively thin thickness to allow light to pass therethrough.

An encapsulating layer 200 is formed on the organic light emitting diode De to protect the organic light emitting diode De from moisture or oxygen from the outside. The sealing layer 200 may be an ultraviolet curing sealant (UV sealant) or a frit sealant, or alternatively may have a structure in which an inorganic film and an organic film are alternately laminated.

The color filter layer 220 is disposed on the sealing layer 200. The color filter layer 220 includes red, green, and blue color filters Rc, Gc, and Bc corresponding to the red, green, and blue subpixels Pr, Pg, and Pb, respectively. Here, the blue color filter Bc may be omitted.

An overcoat layer (not shown) for protecting and planarizing the color filter layer 220 may be further formed between the sealing layer 200 and the color filter layer 220.

An opposing substrate 210 is positioned above the color filter layer 220. The counter substrate 210 may be a glass substrate or a plastic substrate.

Here, the color filter layer 220 may be formed on the counter substrate 210, and the counter substrate 210 on which the color filter layer 220 is formed may be adhered to the substrate 110 including the organic light emitting diode De have.

The organic light emitting diode display according to an embodiment of the present invention may be a top emission type in which light from the light emitting layer 180 is output to the outside through the second electrode 192.

As described above, in the organic light emitting diode display according to the embodiment of the present invention, the organic light emitting diodes De of the red, green and blue sub-pixel regions Pr, Pg and Pb have different device thicknesses. That is, the organic light emitting diodes De of the red, green and blue sub-pixel regions Pr, Pg and Pb have a distance from the bottom surface of the first electrode 162 to the bottom surface of the second electrode 192, The element thickness of the organic light emitting diode De of the red sub pixel region Pr is smaller than the element thickness of the organic light emitting diode De of the green sub pixel region Pg, De).

At this time, by changing the thickness of the light emitting layer 182, more specifically, the thickness of the hole auxiliary layer 182, the device thicknesses of the organic light emitting diodes De of the red, green, and blue sub pixel regions Pr, Pg, Can be different. The thickness of the hole auxiliary layer 182 of the red sub pixel region Pr is made smaller than the thickness of the hole auxiliary layer 182 of the green sub pixel region Pg, (182).

The thickness of the hole assist layer 182 can be determined in consideration of the microcavity effect.

FIG. 6A shows the CIE x color coordinates according to the thickness of the hole assist layer, FIG. 6B shows the CIE y color coordinates according to the thickness of the hole assist layer, FIG. 6C shows the current efficiency according to the hole assist layer thickness . 6A to 6C, the thickness of the hole auxiliary layer 182 of the red sub-pixel region Pr is set to be smaller than the thickness of the hole auxiliary layer 182 of the green sub-pixel region Pg in order to satisfy the required color coordinates while the efficiency is high. The thickness of the hole auxiliary layer 182 in the red sub pixel region Pr is selected to be smaller than the thickness of the layer 182 and the thickness corresponding to the second order cavity condition is selected, The hole assist layer 182 of the region Pg preferably has a thickness corresponding to a third order cavity condition.

More specifically, in order to increase the color reproduction rate, the larger the x coordinate of red is, and the smaller the y coordinate is, the better, and the smaller the x coordinate of green is, the better, and the larger the y coordinate is, the better.

6A and 6B, when the hole assist layer 182 of the red sub-pixel region Pr has a thickness corresponding to the first order cavity condition, the x and y coordinates of red , But it can be seen that the efficiency is not sufficient according to Fig. 6C. On the other hand, when the hole auxiliary layer 182 of the red sub-pixel region Pr has a thickness corresponding to the second-order cavity condition, according to FIGS. 6A and 6B, the x and y coordinates of red satisfy the required color coordinates 6C, the efficiency is also increased compared to the first-order cavity condition. Therefore, it is preferable to select the thickness corresponding to the secondary cavity condition of the hole assist layer 182 of the red sub-pixel region Pr.

On the other hand, when the hole auxiliary layer 182 in the green sub pixel region Pg has a thickness corresponding to the first-order cavity condition, according to FIGS. 6A and 6B, the x and y coordinates of green satisfy the required color coordinates I can not. When the hole auxiliary layer 182 of the green sub pixel region Pg has a thickness corresponding to the secondary cavity condition, the x coordinate of green according to Fig. 6A satisfies the required color coordinate, but according to Fig. 6B The y coordinate of the green does not satisfy the required color coordinate. On the other hand, when the hole auxiliary layer 182 of the green sub pixel region Pg has a thickness corresponding to the third-order cavity condition, according to FIGS. 6A and 6B, the x and y coordinates of the green satisfy the required color coordinates , It can be seen that the efficiency is also relatively high according to Fig. 6C. Therefore, it is preferable to select the thickness corresponding to the third-order cavity condition in the hole auxiliary layer 182 of the green sub pixel region Pg.

As described above, the hole assist layer 182 includes at least one of a hole injection layer and a hole transport layer, and the total thickness of the hole injection layer and the hole transport layer is the thickness of the hole assist layer 182. Therefore, in the red sub-pixel region Pr, the total thickness of the hole injection layer and the hole transport layer corresponds to the secondary cavity condition. In the green sub-pixel region Pg, the total thickness of the hole injection layer and the hole transport layer corresponds to the third- . When the hole auxiliary layer 182 of the red sub-pixel region Pr has a thickness corresponding to a lower order cavity condition, the efficiency is low and the lifetime of the organic light emitting diode may be degraded. When the hole assist layer 182 has a thickness corresponding to a higher order cavity condition, the driving voltage can be increased. For example, the thickness of the hole-assist layer 182 in the red sub-pixel region Pr is 250 nm to 280 nm, the thickness of the hole sub-layer 182 in the green sub-pixel region Pg is 310 nm to 330 nm . At this time, when the thickness of the hole assist layer 182 of the red and green sub pixel regions Pr and Pg is out of the range, yellow light is mixed and emitted in the red and green sub pixel regions Pr and Pg, .

On the other hand, the thickness of the hole assist layer 182 in the blue sub pixel region Pb may be 30 nm to 70 nm.

At this time, the thickness of the hole assist layer 182 may be varied by controlling the thickness of the hole injection layer (HIL) and / or the hole transport layer (HTL) of the red, green and blue sub-pixel regions Pr, Pg and Pb. Generally, since the charge mobility of the hole transport layer (HTL) is larger than that of the hole injection layer (HIL), it is preferable to reduce the thickness variation of the hole transport layer (HTL).

Meanwhile, as mentioned above, the light emitting material layer 184 of the organic light emitting diode of the red and green sub-pixel regions Pr and Pg includes a yellow light emitting material. Such a yellow light emitting material has a relatively long lifetime and can emit yellowish red light or yellowish green light due to the micro-cavity effect.

Therefore, in the organic light emitting diode display device according to the embodiment of the present invention, red and green light can be realized by using a yellow light emitting material, a micro cavity effect, and a color filter.

4A and 4B are cross-sectional views schematically illustrating light emitted from the organic light emitting diode display according to an exemplary embodiment of the present invention. FIG. 5A is a cross- FIG. 5B is a diagram illustrating a spectrum of light output from the red and green sub-pixel regions of the organic light emitting diode display according to the embodiment of the present invention.

As shown in FIGS. 4 and 5A and 5B, the light emitting material layer 184 of the red and green sub-pixel regions Pr and Pg includes a yellow light emitting material, and the yellow light emitting material includes first and second light emitting It has a peak. At this time, the yellow light emitting material has a first emission peak in a wavelength range of 530 nm to 555 nm and a second emission peak in a wavelength range of 590 nm to 620 nm. For example, the yellow luminescent material may be bis [2- (4-tertbutylphenyl) benzothiazolato- N , C 2 '] iridium (acetylactonate) [(t) 4,4'-N, N'-dicarbazole- -bt) 2Ir (acac)].

Here, in the red sub-pixel region Pr, the light emitting material layer 184 including the yellow light emitting material emits orange light, that is, yellowish red light Ry by the micro-cavity effect . The yellowish red light Ry passes through the red color filter Rc and is output as deep red light R.

Further, in the green sub-pixel region Pg, the light emitting material layer 184 including the yellow light emitting material emits yellowish green light Gy by the micro-cavity effect. The yellowish green light Gy passes through the green color filter Gc and is output as deep green light G. [

On the other hand, in the blue sub pixel region Pb, the light emitting material layer 184 contains a blue light emitting material and emits blue light (B). The blue light B passes through the blue color filter Bc and is output as deep blue light B.

As described above, the organic light emitting diode display according to the embodiment of the present invention applies a yellow light emitting material having a relatively long lifetime to the red and green sub-pixel regions Pr and Pg, Red and green light can be realized. Accordingly, the lifetime of the organic light emitting diodes of the red and green sub-pixel regions Pr and Pg can be improved.

Further, the organic light emitting diode display device according to the embodiment of the present invention can omit the polarizing plate by the micro-cavity effect, so that the cost can be reduced.

Although the structure of the upper emission type has been described in the above embodiment, the present invention is also applicable to the structure of the lower emission type.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims. And changes may be made without departing from the spirit and scope of the invention.

110: substrate 122: semiconductor layer
130: gate insulating film 132: gate electrode
140: interlayer insulating film 140a, 140b: first and second contact holes
142: source electrode 144: drain electrode
152, 154: first and second protective films 156: drain contact holes
162: Substrate electrode 170: Bank layer
180: light emitting layer 182: hole assist layer
184: luminescent material layer 186: electron assist layer
192: second electrode

Claims (8)

A red, green, and blue sub-pixel regions are defined;
A first electrode located in each of the red, green and blue sub-pixel regions;
First, second and third emission layers respectively located in the red, green and blue sub-pixel regions of the first electrode;
A second electrode on the first, second, and third light emitting layers;
Green, and blue sub-pixel regions corresponding to the red, green, and blue sub-pixel regions, respectively,
/ RTI >
Wherein the first and second light emitting layers include a yellow light emitting material,
Wherein a thickness of the first light emitting layer is smaller than a thickness of the second light emitting layer.
The method according to claim 1,
Wherein the yellow light emitting material has a first emission peak in a wavelength region of 530 nm to 555 nm and a second emission peak in a wavelength region of 590 nm to 620 nm.
3. The method of claim 2,
The yellow luminescent material was prepared by reacting 4,4'-N, N'-dicarbazole-biphenyl (CBP) with bis [2- (4-tertbutylphenyl) benzothiazolato- N , C 2 '] iridium (acetylactonate) ) 2Ir (acac)].
The method according to claim 1,
Wherein each of the first and second light emitting layers includes a hole assist layer, a light emitting material layer, and an electron assist layer, and the thickness of the hole assist layer of the first light emitting layer is less than the thickness of the hole assist layer of the second light emitting layer. Diode display.
5. The method of claim 4,
Wherein the thickness of the hole-assist layer of the first light-emitting layer is 250 nm to 280 nm, and the thickness of the hole-assist layer of the second light-emitting layer is 310 nm to 330 nm.
5. The method of claim 4,
Wherein the third light emitting layer includes a blue light emitting material, and the third light emitting layer has a thickness smaller than that of the first light emitting layer.
The method according to claim 6,
Wherein the third light emitting layer includes a hole assist layer, a light emitting material layer, and an electron assist layer, and the thickness of the hole assist layer of the third light emitting layer is smaller than the thickness of the hole assist layer of the first light emitting layer.
8. The method of claim 7,
And the thickness of the hole-assist layer of the third light-emitting layer is 30 nm to 70 nm.

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