KR102570979B1 - White Organic Light Emitting Device And Display Device Using the Same - Google Patents

Abstract

The present invention relates to a white organic light emitting device using a modified stack structure and a display device using the same, which can improve luminance and color gamut and expand a color gamut.

Description

White organic light emitting device and display device using the same {White Organic Light Emitting Device And Display Device Using the Same}

The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device that improves luminance and color gamut through a change in a stack structure, and at the same time expands a color gamut, and a display device using the same.

Recently, as we entered the full-fledged information age, the display field that visually expresses electrical information signals has developed rapidly. Display Device) has been developed and is rapidly replacing the existing cathode ray tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an organic light emitting display device. (Organic Light Emitting Device: OLED) etc. are mentioned.

Among them, an organic light emitting display device is being considered as a competitive application for miniaturization of the device and vivid color display without requiring a separate light source.

Such an organic light emitting display device requires the formation of an organic light emitting layer, and a conventional deposition method using a shadow mask has been used to form the organic light emitting layer.

However, when the shadow mask has a large area, sagging occurs due to its load, which makes it difficult to use many times and causes defects in organic light emitting layer pattern formation, so an alternative is required.

As one of the methods proposed to replace the shadow mask, it is referred to as a tandem type white organic light emitting device (hereinafter, referred to as a 'white organic light emitting device'), and the white organic light emitting device will be described below. As follows.

A white organic light emitting device is characterized in that each layer between an anode and a cathode is deposited without a mask when forming a light emitting diode, and organic films including an organic light emitting layer are formed by sequentially varying the components and depositing in a vacuum state. In addition, the white organic light emitting device has different light emitting layers emitting light of a plurality of colors between an anode and a cathode, and a charge generation layer is provided between each light emitting layer, and each light emitting layer is used as a basic structure to divide the stack do.

Such a white organic light-emitting device does not emit light using one material, but a plurality of light-emitting layers including light-emitting materials having different PL peaks (Photoluminescence Peak) for each wavelength emit light at different positions in the device, and are combined to emit light. this occurs

However, stack structures known to date do not have sufficient efficiency as a white organic light emitting device, and there is a problem in that color characteristics change when driving for a long time or changing a viewing angle due to differences in efficiency for each color.

In particular, a generally known multi-stack structure is designed by optimizing a green cavity with good visibility. Therefore, when observing the EL spectrum determined by the product of the curve of the outcoupling emittance spectrum optimally matched to green and the unique PL spectrum of the light emitting layers provided in the multi-stack structure, there is a problem in that the luminous efficiency in the region other than green is lowered. there is.

In addition, in display, there is a demand to implement a sufficient color gamut similar to the actual color representation of nature, but white organic light emitting devices that simply consider peak efficiency in a stack structure cannot meet this demand. there is

The present invention has been made to solve the above problems, and by changing the stack structure and the thickness of the first electrode (anode) to improve luminance and color gamut, and at the same time expand the color gamut, a white organic light emitting device and a display device using the same It is about.

A white organic light emitting device and a display device using the same according to the present invention improve the color gamut according to the arrangement of adjacent light emitting stacks in a stack structure and the thickness of the first electrode or whether a light compensation layer is applied without changing the material of the light emitting layer. It is characterized in that the color gamut is expanded.

A white organic light emitting device according to an embodiment of the present invention includes a transparent first electrode, a reflective second electrode opposite to the first electrode, and a plurality of light emitting stacks between the first and second electrodes, and each light emitting device. Consisting of organic stacks including charge generation layers between the stacks, the first light emitting stack in contact with the first electrode and the second light emitting stack adjacent to the first light emitting stack include a first blue light emitting layer and a second blue light emitting layer, respectively. and the first electrode is thicker than any other layer in the organic stack.

Further, the plurality of light emitting stacks include a plurality of light emitting layers that are in contact with the second light emitting stack and emit light of a longer wavelength than blue, and further include a third light emitting stack that is in contact with the second electrode. has first and second organic common layers respectively contacting the lower and upper surfaces of the first blue light-emitting layer, and the second light-emitting stack has third and fourth organic common layers respectively contacting the lower and upper surfaces of the second blue light-emitting layer. , and the third light emitting stack may have fifth and sixth organic common layers respectively contacting the lowermost and uppermost surfaces of the plurality of light emitting layers.

In addition, the plurality of light emitting layers of the third light emitting stack may include stacked red light emitting layers and green light emitting layers, and the green light emitting layer may be closer to the second electrode than the red light emitting layer.

The first blue light emitting layer, the second blue light emitting layer, the red light emitting layer, and the green light emitting layer may each have a thickness of 100 Å to 400 Å, and the green light emitting layer may be thicker than the first blue light emitting layer, the second blue light emitting layer, and the red light emitting layer. there is.

The organic stack may have a total thickness of 3500 Å to 3800 Å, and a distance between the first and second blue light emitting layers and a distance between the second blue light emitting layer and the lowermost surface of the plurality of light emitting layers of the third light emitting stack may be 400 Å to 1200 Å. there is.

The first electrode may have a thickness of 2400 Å to 2700 Å.

The first electrode may be a transparent oxide electrode including at least one of indium, titanium, zinc, tin, and gallium.

The refractive index of the first electrode may be 1.7 to 2.1.

A light compensation layer having a higher refractive index than the first electrode may be further included in contact with a surface of the first electrode that does not contact the organic stack.

A combined thickness of the light compensation layer and the first electrode may be 2400 Å to 2800 Å.

The refractive index of the light compensation layer may be 2.2 to 2.6.

Here, the optical compensation layer may be a transparent oxide electrode including at least one metal of niobium, indium, titanium, zinc, tin, and gallium.

A display device for achieving the same object includes a substrate having a plurality of sub-pixels, at least one of a thin film transistor provided on each of the sub-pixels and connected to the first electrode of the white organic light emitting device described above, and the sub-pixels. It may include a color filter layer provided under the first electrode of the.

The plurality of sub-pixels include a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel, and the color filter layer is divided into first to third color filters and provided in the remaining sub-pixels except for the white sub-pixel. can

The white organic light emitting diode and the display device using the same according to the present invention have the following effects.

First, a double stack having short-wavelength light-emitting layers is provided adjacent to the anode, which is the emission side electrode, and a plurality of long-wavelength light-emitting layers are provided adjacent to the cathode side, which is the opposite electrode, so that the intensity of the EL spectrum does not decrease at a specific wavelength. , it is possible to improve the luminous efficiency evenly for each wavelength of red, green and blue. That is, even if the organic stack in the white organic light emitting unit is configured by optimizing the green cavity, not only the green light emitting efficiency but also the blue light emitting efficiency is realized with the plurality of stacks, and the plurality of adjacent long-wavelength light emitting layers each have optimal light emitting efficiency. By adjusting the position to have , it is possible to increase the area where the outcoupling emittance spectrum curve and the PL spectrum overlap, thereby improving the luminous efficiency at all wavelengths. Therefore, white balance can be maintained.

Second, a white organic light emitting device and a display device using the same of the present invention arrange a plurality of light emitting layers adjacent to a cathode as a green light emitting layer and a red light emitting layer, and the thickness of the emission side electrode is smaller than any other layer in the organic stack between the anode and the cathode. By making it thick, the light extraction effect can be improved and the luminous efficiency can be improved. Accordingly, the luminance of the entire panel may be increased.

Third, it is possible to obtain an even EL spectrum of red, green, and blue wavelengths, so that luminance can be improved in a panel such as a display device, and an effect of expanding a color gamut can be obtained.

1 is a cross-sectional view showing a white organic light emitting device according to a first embodiment of the present invention.
FIG. 2 is a view showing emission positions for each wavelength in each stack of the white organic light emitting diodes of FIG. 1;
3a and 3b are cross-sectional views illustrating white organic light emitting diodes according to first and second comparative examples;
FIG. 4 is a view showing emission positions for each wavelength in each stack of the white organic light emitting diodes of FIG. 3B.
5 is a graph showing emission spectrum characteristics of a second comparative example and a first white organic light emitting device of the present invention.
6 is a cross-sectional view showing a white organic light emitting device according to a second embodiment of the present invention.
FIG. 7 is a view showing emission positions for each wavelength in each stack of the white organic light emitting diodes of FIG. 6;
8 is a graph showing EL spectrum characteristics of the first and second white organic light emitting diodes of Comparative Example 2 and the present invention;
9 is a graph showing BT709, DCI, and BT 2020 color gamuts
10 is a view showing color gamuts of a display device to which a second comparative example is applied and a display device to which a first embodiment of the present invention is applied;
11 is a cross-sectional view of a display device according to a first embodiment of the present invention;
12 is a cross-sectional view of a display device according to a second embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numbers throughout the specification indicate substantially the same elements. In the following description, if it is determined that a detailed description of a technique or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, the component names used in the following description are selected in consideration of the ease of writing the specification, and may be different from the part names of the actual product.

Since the shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining various embodiments of the present invention are exemplary, the present invention is not limited to those shown in the drawings. Like reference numerals designate like elements throughout this specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

In interpreting the components included in various embodiments of the present invention, even if there is no separate explicit description, it is interpreted as including an error range.

In describing various embodiments of the present invention, in the case of describing the positional relationship, for example, 'on ~', '~ on top', '~ on the bottom', '~ next to', etc. When the positional relationship of parts is described, one or more other parts may be located between two parts unless 'immediately' or 'directly' is used.

In describing various embodiments of the present invention, in the case of explaining the temporal relationship, for example, 'after', 'after', 'after', 'before', etc. When is described, it may also include non-continuous cases unless 'immediately' or 'directly' is used.

In describing various embodiments of the present invention, 'first ~', 'second ~', etc. may be used to describe various components, but these terms are only used to distinguish between identical and similar components. am. Therefore, components modified with 'first to' in this specification may be the same as components modified with 'second to' within the technical spirit of the present invention, unless otherwise noted.

Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each of the various embodiments can be implemented independently of each other or together in an association relationship. may be

In this specification, 'doped' refers to a material that occupies most of the weight ratio of a layer, which has different physical properties from the material that occupies most of the weight ratio (different physical properties, for example, N-type and P-type, organic materials and It means that materials with inorganic substances) are added in a weight ratio of less than 10%. In other words, the 'doped' layer means a layer from which the host material and the dopant material of a certain layer can be separated by considering the specific gravity of the weight ratio. And 'undoped' refers to all cases other than the case corresponding to 'doped'. For example, when a layer is composed of a single material or a mixture of materials having the same properties as each other, the layer is included in the 'undoped' layer. For example, if at least one of the materials constituting a certain layer is P-type and all of the materials constituting the layer are not N-type, the layer is included in the 'undoped' layer. For example, if at least one of the materials constituting a certain layer is an organic material and all of the materials constituting the layer are not inorganic materials, the layer is included in the 'undoped' layer. For example, if all of the materials constituting a layer are organic materials, and at least one of the materials constituting the layer is N-type and at least one of the other materials is P-type, the N-type material It is included in the 'doped' layer if this weight ratio is less than 10% or if the weight ratio of P-type material is less than 10%. The doping concentration of a dopant whose doping concentration is not specifically defined in the following specification is limited to less than 10%, and the defined doping concentration conforms to the corresponding description.

In the present specification, the EL (electroluminescence) spectrum refers to (1) a PL (photoluminescence) spectrum reflecting inherent characteristics of a light emitting material such as a dopant material or a host material included in an organic light emitting layer, ( 2) It is calculated as a product of an out-coupling emittance spectrum curve, which is determined according to the structure and optical characteristics of the organic light emitting device including the thickness of organic layers such as an electron transport layer.

In this specification, the stack refers to a unit structure including a hole transport layer, an organic layer including a sperm transport layer, and an organic light emitting layer disposed between the hole transport layer and the electron transport layer. The organic layer may further include a hole injection layer, an electron blocking layer, a hole blocking layer, and an electron injection layer, and other organic layers may be further included depending on the structure or design of the organic light emitting device.

FIG. 1 is a cross-sectional view showing a white organic light emitting device according to a first embodiment of the present invention, and FIG. 2 is a view showing light emission positions for each wavelength in each stack of the white organic light emitting device of FIG. 1 .

As shown in FIG. 1, the white organic light emitting device 1000 according to the first embodiment of the present invention includes a transparent first electrode 110, a reflective second electrode 170 opposite to the first electrode, and the first electrode 110. , a plurality of light-emitting stacks S1, S2, and S3 between the second electrodes, and an organic stack OS including charge generation layers CGL1 and CGL2 between the light-emitting stacks.

In the white organic light emitting device according to the first embodiment of the present invention, a multi-layered organic stack (OS) made of an organic material is formed between the first electrode 110 and the second electrode 170, and the lower first electrode ( 110) as the emission side, the first electrode 110 is made of a transparent electrode, and the light emitted from each of the light emitting stacks S1, S2, and S3 in the organic stack OS is transmitted in both vertical directions, but the upper third The second electrode 170 is made of a reflective electrode and reflects the light transmitted upward to help emit light downward.

The first electrode 110 is made of a transparent oxide electrode containing at least one of indium, titanium, zinc, gallium, and tin. Examples of the first electrode 110 include indium tin oxide (ITO), indium zinc oxide (IZO), and indium gallium zinc oxide (IGZO).

The second electrode 170 is a reflective electrode and is formed of gold (Au), silver (Ag), aluminum (Al), molybdenum (Mo), magnesium (Mg), etc., or an alloy containing at least one of these metals. can In some cases, each or any one of the first and second electrodes 110 and 170 may be a plurality of layers.

In the organic stack OS between the first electrode 110 and the second electrode 170, light is emitted from the light emitting layers in each light emitting stack, and the light is emitted from the interface between the second electrode 170 and the organic stack OS. and the position of each light emitting layer so that the first electrode 110 resonates between the interface facing the organic stack OS and emits light to the outside (lower surface in the drawing) of the first electrode 110 to optimally have a cavity. is adjusted

Specifically, the plurality of light emitting stacks provided include, in order from the bottom, a first light emitting stack S1 in contact with the first electrode 110 and a second light emitting stack S2 adjacent to the first light emitting stack S1. and a third light emitting stack S3 emitting light having a longer wavelength than the first and second light emitting stacks S1 and S2 onto the second light emitting stack S2.

Each of the first to third light emitting stacks S1 to S3 includes an emission layer and an organic common layer on a lower portion and an upper portion thereof. In the white organic light emitting device according to the first embodiment of the present invention, the short wavelength blue light emitting layer is provided in the first and second light emitting stacks S1 and S2 adjacent to the emission side. This is because the entire organic stack (OS) is tailored to the cavity characteristics of green with high visibility, in order to increase the luminous efficiency of blue with relatively low cavity efficiency and low visibility, as shown in FIG. The light emitting stacks S1 and S2 are provided, and a sufficient optical distance is secured in each of the two blue light emitting layers 123 and 142 so that the characteristics of the other color cavities are not affected, thereby sufficiently securing blue light emitting efficiency.

In addition, in the first embodiment of the present invention, the thickness of the first electrode 110 is made thicker than any layer in the organic stack OS, so that the entire thickness in the organic stack OS made of organic materials is 3500 Å to 3800 Å. , It is possible to reduce the amount of organic material deposition required for a white organic light emitting device, thereby reducing the material in the organic stack, which is a major factor in process cost. As shown in FIG. 2, within the reduced total thickness of the organic stack (OS), in the third light-emitting stack (S3) that emits long-wavelength light, a portion having optimal red and green light emitting efficiency is generated gently across the green and red wavelength bands. Therefore, it is possible to set adjacent red light emitting layers 162 and green light emitting layers 163 without loss of light emitting efficiency of a specific wavelength.

Specifically, the configuration in the organic stack (OS) will be described.

The first light emitting stack S1 includes a hole injection layer 121 , a first hole transport layer 122 , a first blue light emitting layer 123 , and a first electron transport layer 124 in order from the bottom. The hole injection layer 121 helps smoothly inject holes from the first light emitting stack S1 into the organic stack OS, and the first hole transport layer 122 transfers the injected holes to the first blue light emitting layer 123. And, the second electron transport layer 124 supplies electrons from the first charge generating layer 130 to the first blue light emitting layer 123 .

On the first light emitting stack S1, the first charge generation layer 130 including an n-type charge generation layer (nCGL) and a p-type charge generation layer (pCGL) is provided. The n-type charge generation layer (nCGL) in the first charge generation layer 130 is involved in the generation of electrons, and the p-type charge generation layer (pCGL) is involved in the generation of holes, so that the adjacent first light emitting stack (S1) and the second 2 Electrons and holes are transferred to the light emitting stack S2.

The second light emitting stack S2 includes the second hole transport layer 141, the second blue light emitting layer 142, and the second electron transport layer similarly to the first light emitting stack S1 except that the hole injection layer is not provided. (143) and is provided on the first charge generating layer (130). The second hole transport layer 141 and the second electron transport layer 143 have the same function as the first hole transport layer 122 and the first electron transport layer 124 described above. Here, the second hole transport layer 141 and the second electron transport layer 143 may be formed of the same material as or a different material from the first hole transport layer 122 and the first electron transport layer 124 described above, and the second To set the optical distance of the blue light emitting layer 142, a thickness different from that of the first hole transport layer 122 and the first electron transport layer 124 may be applied.

A second charge generation layer 150 composed of an n-type charge generation layer (nCGL) and a p-type charge generation layer (pCGL) is provided on the second light emitting stack (S2). The second charge generating layer 130 may have the same thickness and the same material as the first charge generating layer 130 .

Subsequently, a third light emitting stack composed of a third hole transport layer 161, a red light emitting layer 162, a green light emitting layer 163, and a third electron transport layer 164 is sequentially formed on the second charge generation layer 150 ( S3) is formed. The third hole transport layer 161 and the third electron transport layer 164 may be formed of the same material as the above-described first hole transport layer 122 and the first electron transport layer 124 or a different material, and the red light emitting layer 162 ) and a thickness different from that of the first hole transport layer 122 and the first electron transport layer 124 may be applied to set the optical distance of the green light emitting layer 163 .

Subsequently, an electron injection layer 165 and a second electrode 170 are provided on the third light emitting stack S3. The electron injection layer 165 is a thin layer of 10 nm or less, and when an organic material is included in the electron injection layer 165, it is also regarded as a configuration of an organic stack (OS), and an inorganic compound or an inorganic compound and a metal dopant are used. When included, it is also regarded as an outer configuration of the organic stack (OS). In the case of including an inorganic compound, it may be formed using the same mask as the mask for forming the second electrode 170 before forming the second electrode 170 .

Hereinafter, materials and functions of components in the organic stack OS will be described.

The hole injection layer 121 is made of MTDATA (4,4',4"-tris(3-methylphenylphenylamino)triphenylamine), CuPc (copper phthalocyanine), PEDOT/PSS (poly(3,4-ethylenedioxythiphene, polystyrene sulfonate), or the like. It can be made, but is not necessarily limited thereto.

In the first blue light emitting layer 123, since holes supplied through the first hole transport layer (HTL) 112 and electrons supplied through the first electron transport layer (ETL) 116 are recombinated, light is emitted. is created

The first, second, and third hole transport layers 122, 141, and 161 may be formed by applying two or more layers or two or more materials having different component ratios in some cases. The first, second and third hole transport layers 122, 141 and 161 are NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'- dimethylbenzidine), TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine) and Spiro-TAD (2,2'7,7'tetrakis(N,Ndiphenylamino) -9,9'-spirofluorene), but may consist of one or more selected from the group consisting of, but is not limited thereto.

The first, second, and third electron transport layers 124, 143, and 164 may also be formed by applying two or more layers or two or more materials with different component ratios depending on circumstances. The first, second, and third electron transport layers 124, 143, and 164 are PBD (2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), TAZ (3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), BAlq(Bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium), Liq (8-hydroxyquinolinolato-lithium), TPBi (2,2', 2' - (1,3,5-benzinetriyl) -tris (1-phenyl-1-H-benzimidazole) consisting of at least one selected from the group consisting of may, but is not limited thereto.

Between the first blue light emitting layer 123 and the first electron transport layer 124, between the second blue light emitting layer 142 and the second electron transport layer 142, and between the green light emitting layer 163 and the third electron transport layer 164 Any one or any two or both of them may further configure a hole blocking layer (HBL). The hole blocking layer HBL prevents holes injected into the light emitting layers 123 , 142 , 162 , and 163 of each light emitting stack S1 , S2 , and S3 from passing to an adjacent electron transport layer, and blocks holes in the light emitting layer. It is possible to increase the probability of recombination with electrons in the light emitting layer by maintaining it. The material of the hole blocking layer may be the same as that of the above-described electron transport layer, or a specific organic material or metal may be substituted thereto to increase a difference in HOMO level between the light emitting layer and the hole blocking layer.

In addition, between the first blue light emitting layer 123 and the first hole transport layer 122, between the second blue light emitting layer 142 and the second hole transport layer 141, and between the red light emitting layer 162 and the third hole transport layer ( 161), any one or any two or both electron blocking layers (EBL) may be additionally configured. The electron blocking layer EBL prevents electrons injected into the light emitting layers 123, 142, 162, and 163 of each light emitting stack S1, S2, and S3 from passing to the adjacent hole transport layer, and prevents electrons in the light emitting layer. It is possible to increase the probability of recombination with holes in the light emitting layer by maintaining it. The material of the electron blocking layer may be the same as the material of the electron transport layer described above, or a specific organic material or metal may be substituted thereto to increase a LUMO level difference between the light emitting layer and the electron blocking layer.

The first and second blue light emitting layers 123 and 142 emit light having a peak wavelength of 430 nm to 490 nm, and may have different wavelength characteristics depending on dopants. The range of blue may include, in addition to the range generally referred to as blue with a peak wavelength of 440 nm to 480 nm, a lower range of deep blue or an upper range of sky blue. In addition, the first blue light emitting layer 123 and the second blue light emitting layer 142 use the same dopant but vary the dopant content to perform optimal light emission for each optical distance, or use different dopants to achieve a blue wavelength light emitting range. can increase Hosts of the first and second blue light emitting layers 123 and 142 may be composed of a single material or a mixed host composed of mixed materials. Examples of hosts include Alq3 (tris(8-hydroxy-quinolino)aluminum), ADN (9,10-di(naphtha-2-yl)anthracene), BSBF (2-(9,9-spirofluoren-2-yl)- 9,9-spirofluorene) materials or a mixture of two or more can be selected. It is not necessarily limited to this. Dopants of the first and second blue light emitting layers 123 and 142 may be made of pyrene. More specifically, it may consist of a pyrene-based compound in which an aryl amine-based compound is substituted, but is not necessarily limited thereto.

As shown in FIGS. 1 and 2 , the light emitting layer in the third light emitting stack S3 includes a red light emitting layer 162 and a green light emitting layer 163 independently. This is for sufficient color reproduction of each of green and red. Also, here, the reason why the arrangement of the light emitting layers 162 and 163 emitting different colors comes to the third light emitting stack S3 is, as shown in FIG. This is because optimum light emission of green and blue wavelengths can occur in gently adjacent areas, and thus the arrangement of the red light emitting layer 162 and the green light emitting layer 163 can be arranged at adjacent positions each having optimum light emitting efficiency.

Meanwhile, each of the red light emitting layer 162 and the green light emitting layer 163 may be formed by being divided into multiple layers. In this case, the dopant may be made of the same material in each layer for each light emitting color, but the dopant concentration may be different.

Each host of the red light emitting layer 162 and the green light emitting layer 163 may be composed of a single material or a mixed host made of a mixed material. In consideration of the fact that the red light emitting layer 162 assists hole transport with respect to the green light emitting layer 163, only a host having strong hole transport characteristics is used in the red light emitting layer 162, or a first host having hole transport characteristics and electrons are used. It may be provided by increasing the content of the first host among the second hosts having transport characteristics. In this case, the red light emitting layer 162 functions as a hole transport layer for both red light emission and green light emission in the third light emitting unit S3.

For example, the host of the red light emitting layer 162 and the green light emitting layer 163 is CBP (4,4'-bis(carbazol-9-yl)biphenyl), spiro-CBP (2,2',7,7'- It may include one of tetrakis (carbazol-9-yl) -9,9' -spirobifluorene) and TCTA (4,4', 4' -tris (carbazol-9-yl) triphenylamine), but the red light emitting layer (162) For the hole transport function, a host of material different from that of the green light emitting layer 163 may be used. However, it is not necessarily limited thereto.

The dopants of the red light emitting layer 162 each have a peak wavelength at a wavelength of 600 nm to 645 nm, and the green light emitting layer 163 has a peak wavelength at a wavelength of 510 nm to 590 nm. ) series compound, but is not necessarily limited thereto.

The red light emitting layer 162 has a peak wavelength at a wavelength of 600 nm to 645 nm, and the green light emitting layer 163 has a peak wavelength at a wavelength of 510 nm to 590 nm.

In some cases, a buffer layer (not shown) may be further provided between the red light emitting layer 162 and the green light emitting layer 163 . In such a white organic light emitting device, green, which is the center of visible light wavelength, contributes the most to the luminance characteristics. 1, it is thicker than the second blue light emitting layers 123 and 142, and is formed to a thickness of about 250 Å to 450 Å. The first and second blue light emitting layers 123 and 142 and the red light emitting layer 162 are formed thinner than the green light emitting layer 163 by a thickness of 50 Å to 200 Å. Approximately, the thickness of the first and second blue light emitting layers 123 and 142 and the red light emitting layer 162 is in the range of 100 Å to 400 Å. In addition, the dopant content provided in the green light emitting layer 163 is also included in the range of about 7wt% to 20wt%, including the largest among the light emitting layers of each color. On the other hand, the first and second blue light-emitting layers 123 and 142 and the red light-emitting layer 162 are doped in a range of 0.1 wt% to 10 wt%.

The N-type charge generating layer (nCGL) of the first and second charge generating layers 130 and 150 is an alkali metal such as lithium (Li), sodium (Na), potassium (K), or cesium (Cs), or It may be made of an organic layer doped with an alkaline earth metal such as magnesium (Mg), strontium (Sr), barium (Ba), or radium (Ra), but is not necessarily limited thereto. The P-type charge generation layer (pCGL) of the first and second charge generation layers 130 and 150 may be formed of an organic layer containing a P-type dopant, but is not necessarily limited thereto. For example, HATCN may be used as a P-type dopant.

In some cases, the charge generation layer may be formed as a single layer without separating the p-type charge generation layer and the n-type charge generation layer.

The distance L2 between the first and second blue light-emitting layers 123 and 142 in the organic stack OS and the top surface of the plurality of light-emitting layers of the second blue light-emitting layer 142 and the third light-emitting stack, that is, , The distance L1 between the lower surfaces of the red light emitting layer 162 is 400 Å to 1200 Å, respectively, which is the charge generating layer 130 or 150 between the light emitting stacks, the electron transport layer of the previous light emitting stack, and the holes of the next light emitting stack. is the sum of the thicknesses of the transport layer.

In the white organic light emitting device according to the first embodiment of the present invention, the first electrode 110 has a thickness of 2400 Å to 2700 Å, which is thicker than a typical bottom emission type structure, and the second electrode 170 ) has a thickness smaller than that of a general bottom emission type structure. Also, the transparent first electrode 110 has a refractive index of 1.7 to 2.1, and has a refractive index similar to that of organic layers of the organic stack OS having a refractive index of approximately 1.4 to 2.5.

Hereinafter, a white organic light emitting device according to a comparative example will be described and compared with the white organic light emitting device of the present invention.

3A and 3B are cross-sectional views showing white organic light emitting diodes according to the first and second comparative examples, and FIG. 4 is a view showing emission positions for each wavelength in each stack of the white organic light emitting diodes of FIG. 3b.

As shown in FIG. 3A , the white organic light emitting diode according to Comparative Example 1 includes first and second light emitting stacks S1 and S2 with the charge generation layer CGL interposed between the anode and the cathode, and The first light-emitting stack S1 includes a blue light-emitting layer B, and the second light-emitting stack S2 includes a yellow-green light-emitting layer YG.

An organic common layer such as a hole transport layer and an electron transport layer is further provided on the lower and upper surfaces of the light emitting layers B and YG of the first light emitting stack S1 and the second light emitting stack S2.

As shown in FIG. 3B, the white organic light emitting diode according to Comparative Example 2 compensates for the blue efficiency that is insufficient in Comparative Example 1, and includes first and second charge generation layers CGL1 and CGL2 between the anode and the cathode. ) are provided with the first to third light emitting stacks S1, S2, and S3 interposed therebetween, the first light emitting stack S1 includes the first blue light emitting layer B1, and the second light emitting stack S2 includes the first blue light emitting layer B1. The red light emitting layer R and the green light emitting layer G are provided in contact with each other, and the third light emitting stack S3 includes a second blue light emitting layer B2.

An organic common layer such as a hole transport layer and an electron transport layer is further provided on the lower and upper surfaces of the light emitting layers B1, G, and B2 of the first to third light emitting stacks S1, S2, and S3 according to the second comparative example. there is.

Compared to the structure of FIG. 1 (first embodiment of the present invention) described above, in the second comparative example, the thickness of the entire organic stack is 4100 Å or more to match the optimal green cavity in the organic stack, and the thickness of the anode corresponds to a thickness of 1200 Å. Compared to the first embodiment of the present invention, the second comparative example has a difference in arrangement of the second light emitting stack having a second blue light emitting layer and the third light emitting stack having red and green light emitting layers, the first electrode (anode) It has a difference in thickness and the thickness of the entire organic stack, and the material of each layer has the same properties.

As shown in FIG. 3B, in the white organic light emitting device according to Comparative Example 2, the second blue light emitting layer is positioned in the third light emitting stack S3, and the red and green light emitting layers R and G are provided at the R, G, and B emission peaks. When positioned adjacent to the second light emitting stack S2 having a large change, as shown in FIG. 4 , the red light emitting layer R is limited to a position having a low light emitting efficiency, and the red light emitting efficiency is not sufficiently reproduced.

5 is a graph showing emission spectrum characteristics of Comparative Example 2 and the first white organic light emitting device of the present invention.

5, comparing the outcoupling emittance spectrum characteristics between the second comparative example and the white organic light emitting device according to the first embodiment of the present invention, the white organic light emitting device of the second comparative example has cavity characteristics for green light emission The organic stack is adjusted accordingly, and the efficiency of red light emission decreases, and the efficiency of blue light emission of the first and third light-emitting stacks is also observed to be lower than that of green.

On the other hand, in the outcoupling emittance spectrum of the white organic light emitting device according to the first embodiment of the present invention, the green luminous efficiency is slightly lower than that of Comparative Example 2, but the difference is insignificant and is not visible. It can be seen that the luminous efficiency increases in both blue and red. In particular, the emittance curve at the wavelength of 628 nm of red color is 1.96 (a.u.) in the second comparative example, whereas the first embodiment of the present invention is 3.63 (a.u.). And it can be seen that the red luminous efficiency increases by more than two times compared to the second comparative example according to the application of the thickness of the first electrode.

Hereinafter, a white organic light emitting device according to a second embodiment having an efficiency equivalent to or higher than that of the white organic light emitting device according to the first embodiment described above will be described.

6 is a cross-sectional view showing a white organic light emitting device according to a second embodiment of the present invention, and FIG. 7 is a view showing light emission positions for each wavelength in each stack of the white organic light emitting device of FIG. 6 .

6, compared to the first embodiment of FIG. 1, the white organic light emitting device 2000 according to the second embodiment of the present invention further includes a light compensation layer 180 below the first electrode 110. One has a characteristic.

Here, the optical compensation layer 180 is included on a surface of the first electrode 110 that does not contact the organic stack OS, the optical compensation layer 180 is transparent, and the first electrode 110 ) and is closer to the exit side. A refractive index of the light compensation layer 180 may be approximately 2.2 to 2.6. The light compensation layer 180 can improve the amount of light extraction toward the emission side. For example, the optical compensation layer 180 may be a transparent oxide electrode including at least one of niobium (Nb), indium (In), titanium (Ti), zinc (Zn), and tin (Sb).

Here, the combined thickness of the light compensation layer 180 and the first electrode 110 may be 2400 Å to 2900 Å. The intrinsic thickness of the photo-compensation layer 180 is 100 Å or less. When light passes through the photo-compensation layer 180 from the organic stack OS through the first electrode 110, the photo-compensation layer 180 does not absorb the light. and increases the amount of light extraction at the interface with the first electrode 110.

Looking at the light emitting characteristics according to the second embodiment of the present invention through FIG. 7 , the positions of the first and second blue light emitting layers of the first and second light emitting stacks and the positions of the red light emitting layer and the green light emitting layer of the third light emitting stack are It can be seen that the optimal light emitting characteristics are exhibited at almost the same positions as those of the first embodiment.

As a result of multiplying the EL spectrum of the second comparative example and the first and second white organic light emitting diodes in the following experiment, the emission curve of outcoupling shown in FIG. 5 and the PL spectrum characteristic of the dopant of each light emitting layer are multiplied Examine the EL spectrum characteristics.

Meanwhile, the white organic light emitting device 1000 according to the first embodiment and the white organic light emitting device 2000 according to the second embodiment have the same structure (same material, same arrangement of each layer in the organic stack). The difference is only in whether the compensation layer 180 is applied, and the light compensation layer 180 is made of Nb ₂ O ₅ and has a thickness of 100 Å. As described above, in Comparative Example 2, the second light-emitting stack and the third light-emitting stack are displaced (a stack having a long-wavelength light-emitting layer is located in the middle between the two electrodes), and the thickness of the first electrode is different. The same material as that of the corresponding layer in the first and second embodiments was used for each stack in the organic stack, except that the thickness of the organic stack was different.

8 is a graph showing EL spectrum characteristics of the first and second white organic light emitting devices of Comparative Example 2 and the present invention, and FIG. 9 is a display device to which Comparative Example 2 is applied and the first and second embodiments of the present invention. It is a diagram showing the color gamut of the display device to which the example is applied.

As shown in FIG. 8, comparing the white organic light emitting device according to the second comparative example and the first embodiment of the present invention, when the first embodiment of the present invention is applied, the efficiency at the peak wavelength of red is 59 compared to the second comparative example. It can be seen that the increase of more than %. In addition, when the first embodiment of the present invention is applied, there is a slight difference from the second comparative example in green and red, but it can be seen that the change is negligible compared to the change in red. In detail, look at Table 1 below.

Compare Comparative Example 2 Example 1 2nd embodiment Efficiency (Cd/A)
(at full white) R 100% 168% 159% G 100% 98% 105% B 100% 91% 95% W 100% 101% 104% Efficiency (Cd/A)
(at peak wavelength) R 100% 168% 159% G 100% 98% 105% B 100% 91% 95% W 100% 101% 104% color coordinates Rx - 0.01 0.01 Ry - 0.00 0.00 Gx - -0.03 -0.02 Gy - 0.01 0.02 Bx - 0.00 0.00 By - 0.00 0.00 Wx - 0.03 0.02 Wy - 0.02 0.01 color gamut DCI_area 100% 103% 105% DCI_overlap 100% 100% 100% BT2020_area 100% 103% 105% BT2020_Overlap 100% 103% 104% panel luminance FW (RGB) 100% 135% 144% Peak (RGB) 100% 134% 142% FW(WCT) 100% 127% 134% Peak (WCT) 100% 125% 131%

In Table 1, the standards for efficiency (at full white, at peak wavelength), color coordinates, color gamut and panel luminance are the values of the second comparative example, and the first and second examples are compared with the second comparative example. Looking at Table 1 above, the luminous efficiency of red in the first and second examples was improved by more than 59% compared to Comparative Example 2 in terms of full white and peak wavelength respective efficiencies, and green and blue It can be seen that the luminous efficiency of is similar to that of the second comparative example.

In addition, when the first and second embodiments of the present invention are applied in the luminous efficiency of green and blue when white is implemented, there is a slight decrease compared to the second comparative example, but the efficiency of white itself is the first and second embodiments of the present invention 2 It can be seen that all improvements compared to Comparative Example. This means that when the structure of the white organic light emitting device of the present invention is applied, the balance of white color is improved, and no color change is observed when the device is driven for a long time.

On the other hand, the color coordinates in Table 1 are the comparison of the CIEx and CIEy values in R, G, B, and W of the comparative example and the CIEx and CIEy values in R, G, B, and W of the first and second embodiments of the present invention. Referring to 9, it can be seen that the color gamut of red and green is expanded when the first or second embodiment of the present invention is applied.

Hereinafter, the first electrode in the first embodiment and the second embodiment of the present invention is separated by 100 Å from 2300 Å to 2900 Å, respectively, and the efficiency (at full white, at peak wavelength), color coordinates, color gamut and panel luminance characteristics Note the change and the change in at full white, at peak wavelength). This indicates the basis for setting the thickness of the first electrode to 2400 Å to 2700 Å in the embodiments of the present invention.

9 is a graph showing BT709, DCI, and BT 2020 color gamuts, and FIG. 10 is a diagram showing color gamuts of a display device to which the second comparative example is applied and a display device to which the first and second embodiments of the present invention are applied.

Meanwhile, in Tables 2 and 3, WCT represents white color temperature, which means white color temperature.

9 shows the standard ranges of BT 709 (sRGB), DCI, and BT2020 color gamuts, which are defined as triangles with green at the top left, blue at the bottom left, and red at the bottom right, respectively, within the generally known CIE1931. As a current HDTV display color standard, the DCI color gamut has a larger area than BT709, and the BT2020 color gamut has a larger area than BT709. Each DCI represents a color gamut excellent for movie expression, and BT2020 represents a color gamut suitable for UHDTV.

Compare Comparative Example 2 First Embodiment (Variation of First Electrode (ITO) Thickness (Å)) 2300 2400 2500 2600 2700 2800 2900 Efficiency (Cd/A)
(at FW) R 100% 174% 173% 171% 168% 145% 134% 145% G 100% 87% 92% 95% 98% 104% 97% 84% B 100% 91% 90% 100% 91% 100% 101% 89% W 100% 98% 99% 171% 101% 105% 104% 97% Efficiency (Cd/A)
(at peak) R 100% 174% 173% 171% 168% 145% 134% 145% G 100% 87% 92% 95% 98% 104% 97% 84% B 100% 91% 90% 91% 91% 100% 101% 89% W 100% 98% 99% 100% 101% 105% 104% 97% color coordinates Rx - 0.01 0.01 0.01 0.01 0.01 0.01 0.00 Ry - 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Gx - -0.02 -0.03 -0.03 -0.03 -0.01 0.01 -0.01 Gy - 0.00 0.00 0.01 0.01 0.01 -0.01 -0.02 Bx - 0.00 0.00 0.00 0.00 0.00 0.00 0.00 By - 0.01 0.01 0.00 0.00 0.00 0.01 0.01 Wx - 0.05 0.04 0.04 0.03 0.02 0.02 0.04 Wy - 0.02 0.02 0.02 0.02 0.01 0.01 0.02 color gamut DCI area 100% 99% 101% 102% 103% 103% 99% 96% DCI nesting 100% 99% 100% 100% 100% 100% 100% 99% BT2020 area 100% 99% 101% 102% 103% 103% 99% 96% BT2020 nesting 100% 100% 102% 103% 103% 103% 100% 98% panel luminance FW(RGB) 100% 123% 129% 132% 135% 141% 132% 116% Peak (RGB) 100% 97% 109% 117% 127% 134% 125% 102% FW(WCT) 100% 122% 128% 131% 134% 140% 131% 115% Peak (WCT) 100% 98% 108% 116% 125% 132% 123% 101%

In Table 2, as in the first embodiment of the present invention, when the second light emitting stack and the third light emitting stack are replaced with respect to the second comparative example, the red light emitting efficiency increases with all changes in the thickness of the first electrode (2300 Å to 2900 Å). indicates that However, this structural change also causes a change in the luminous efficiency in green or blue, and looking again from the white balance point of view considering all red, blue, and green, the efficiency is equivalent to that of the comparative example at the thicknesses of the first electrode tested (approximately 3 It can be seen that the % difference is regarded as equivalent level considering the error) or rises. However, when the thickness of the first electrode is 2300 Å, which is thinner than the thickness of the first electrode of the present invention, compared to the second comparative example, the DCI area and the DCI overlapping area are 99%, out of the DCI standard by 1%, The BT2020 area is also at the 99% level, and it can be seen that the color gamut is reduced compared to the second comparative example. That is, when the thickness of the first electrode is 2300 Å, the panel luminance has an increased side compared to Comparative Example 2, but the color gamut is reduced, and the full white luminance is reduced by 3% at the color temperature of white compared to Comparative Example 2, and the peak wavelength The luminance is reduced by 2%, which means that the white color property is not excellent in display properties.

In addition, when the thickness of the first electrode is set to 2800 Å to be thicker than the thickness of the first electrode of the present invention, the color coordinate Gy value is reduced compared to the second comparative example, and thus both the DCI area and the BT2020 area are reduced. If the thickness of the first electrode is increased to 2900 Å, the reduction in the color gamut becomes more severe.

Therefore, in the white organic light emitting diode according to the first embodiment of the present invention, the thickness of the first electrode having an excellent range is set to 2400 Å to 2700 Å in consideration of the increase in the color gamut and the overall white efficiency and the panel. In this case, the thickness of the first electrode is such that the first and second light emitting stacks are provided with the first and second blue light emitting layers close to the transparent first electrode as the emission electrode, and the third light emitting stack is close to the second electrode as the reflective electrode. It has an effect in a structure in which a red light emitting layer and a green light emitting layer are arranged in

Compare Comparative Example 2 Second Embodiment (Application of Light Compensation Layer: 100 Å) First electrode (ITO) change [Å] 2200 2300 2400 2500 2600 2700 2800 Efficiency (Cd/A)
(at FW) R 100% 181% 176% 168% 159% 139% 132% 138% G 100% 86% 93% 100% 105% 106% 103% 82% B 100% 91% 90% 91% 95% 103% 105% 91% W 100% 97% 99% 101% 104% 107% 106% 96% Efficiency (Cd/A)
(at peak) R 100% 86% 176% 168% 159% 139% 132% 138% G 100% 87% 93% 100% 105% 106% 103% 82% B 100% 91% 90% 91% 95% 103% 105% 91% W 100% 97% 99% 101% 104% 107% 106% 96% color coordinates Rx - 0.01 0.01 0.01 0.01 0.01 0.01 0.00 Ry - 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Gx - -0.03 -0.03 -0.03 -0.02 -0.01 0.01 0.00 Gy - 0.00 0.01 0.01 0.02 0.01 0.00 -0.02 Bx - 0.00 0.00 0.00 0.00 0.00 0.00 0.00 By - 0.01 0.01 0.00 0.00 0.00 0.00 0.01 Wx - 0.05 0.04 0.03 0.02 0.01 0.01 0.05 Wy - 0.02 0.02 0.02 0.01 0.01 0.01 0.03 color gamut DCI area 100% 98% 101% 102% 103% 103% 99% 96% DCI nesting 100% 99% 100% 100% 100% 100% 100% 99% BT2020 area 100% 98% 101% 102% 103% 103% 99% 96% BT2020 nesting 100% 100% 102% 103% 103% 103% 100% 98% panel luminance FW(RGB) 100% 122% 130% 138% 144% 140% 135% 138% Peak (RGB) 100% 92% 106% 131% 134% 131% 127% 82% FW(WCT) 100% 121% 129% 137% 142% 140% 135% 91% Peak (WCT) 100% 93% 105% 128% 131% 129% 126% 96%

Through the experiments of Table 3 and FIG. 10, in the white organic light emitting diode according to the second embodiment of the present invention, it is preferable that the combined thickness of the light compensation layer and the first electrode is 2400 Å to 2800 Å. In Table 3, in the second embodiment of the present invention, similar to the first embodiment, when the second light emitting stack and the third light emitting stack are replaced with respect to the second comparative example, the red light emitting efficiency is changed in the thickness of the first electrode (2200 Å to 2800 Å) shows an increase in all. However, this structural change also causes a change in the luminous efficiency in green or blue, and looking again from the viewpoint of white balance considering all of red, blue, and green, the experimental example of the second embodiment except for the case where the thickness of the first electrode is 2800 Å , it can be seen that the efficiency is equivalent to that of the comparative example (identified as an equivalent level considering the error of about 3% difference) or rises at the thicknesses of the first electrode tested.

By the way, when the thickness of the first electrode is 2200 Å, which is thinner than the thickness of the first electrode of the present invention, and the sum of the thickness of the 100 Å thick light compensation layer and the first electrode is 2300 Å, DCI compared to the second comparative example Area and DCI overlap area of 98%, which is out of the range of 2% from the DCI standard, and the area of BT2020 is also 98%, indicating that the color gamut is reduced compared to the second comparative example. That is, when 100 Å of the light compensation layer is applied, when the thickness of the first electrode on the top is 2200 Å, the panel luminance has an increased side compared to the second comparative example, but the color gamut is reduced, and the color temperature of white compared to the second comparative example , the full white efficiency decreases by 8% and the peak wavelength efficiency decreases by 7%, which means that white characteristics are not excellent in display characteristics.

In addition, when the thickness of the first electrode is set to 2800 Å and the thickness of the first electrode is thicker than the range of the second embodiment of the present invention, the color coordinate Gy value is reduced by -0.02 compared to the second comparative example, resulting in a DCI area and The BT2020 area will all be reduced. If the thickness of the first electrode is made thicker than this, the reduction of the color gamut becomes more severe.

Therefore, the white organic light emitting diode according to the second embodiment of the present invention preferentially considers the increase in color gamut, and considers the overall white efficiency and the panel together, so that the combined thickness of the first electrode and the light compensation layer has an excellent range. is set to 2400 Å to 2800 Å, the thickness of the first electrode is provided with the first and second blue light emitting layers in the first and second light emitting stacks close to the transparent first electrode as the emission electrode, and the second electrode as the reflective electrode. It has an effect in a structure in which the red light emitting layer and the green light emitting layer are disposed closely to the third light emitting stack.

10 is a comparison of color gamuts between Comparative Example 2 and Example 1 of the present invention. In Comparative Example 2, in the example of FIG. 3B, the thickness of the first electrode was 1200 Å, and the first and second examples In the structure of FIG. 1, as shown in the examples of Tables 1 and 2, the thickness of the first electrode was set to 2600 Å and 2500 Å, respectively.

As shown in FIG. 10, when the first embodiment of the present invention is applied, the color gamut can be expanded compared to the second comparative example, and the color coordinates of white are shifted to the upper right, the color temperature is lowered, and the cool white characteristic is exhibited, under the same current density condition. It has the effect of increasing the amount of light, so it is possible to obtain the effect of increasing the panel luminance, and it is possible to display a white color close to sunlight. The second embodiment can also obtain an extension of the color gamut similar to that of the first embodiment described above.

Hereinafter, a display device to which the white organic light emitting device of the present invention is applied will be described.

11 is a cross-sectional view illustrating a display device according to a first embodiment of the present invention.

As shown in FIG. 11 , the display device according to the first embodiment of the present invention includes a substrate 100 having a plurality of sub-pixels R_SP, G_SP, B_SP, and W_SP, and provided on each of the sub-pixels. A thin film transistor (TFT) connected to the first electrode 110 or the light compensation layer 180 of the white organic light emitting device 1000 according to the embodiment or the white organic light emitting device 2000 according to the second embodiment, and the At least one of the sub-pixels may include color filter layers 109R, 109G, and 109B provided below the first electrode 100 .

The thin film transistor (TFT) includes, for example, a gate electrode 102, a semiconductor layer 104, and a source electrode 106a and a drain electrode 106b connected to both sides of the semiconductor layer 104.

A gate insulating layer 103 is provided between the gate electrode 102 and the semiconductor layer 104 .

The semiconductor layer 104 may be formed of, for example, amorphous silicon, polycrystalline silicon, an oxide semiconductor, or a combination of two or more of these. For example, when the semiconductor layer 104 is an oxide semiconductor, an etch stopper 105 is further provided in direct contact with the semiconductor layer 104 to prevent damage to the channel portion of the semiconductor layer 104. can

In addition, the drain electrode 106b of the thin film transistor TFT may be connected to the first electrode 110 in a contact hole CT area provided in the first and second passivation layers 107 and 108 .

The first passivation layer 107 is primarily provided to protect the thin film transistor TFT, and color filters 109R, 109G, and 109B may be provided thereon.

When the plurality of sub-pixels include a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel, the color filter layer applies first to third color filters to the remaining sub-pixels except for the white sub-pixel W_SP. It is divided into (109R, 109G, 109B), and passes the white light emitted through the first electrode 110 for each wavelength. A second passivation layer 108 is formed under the first electrode 110 to cover the first to third color filters 109R, 109G, and 109B. The first electrode 110 is formed on the surface of the second passivation layer 108 excluding the contact hole CT.

Here, the white organic light emitting device 1000 is formed between the transparent first electrode 110 described in FIG. This refers to a configuration composed of first to third light emitting stacks S1 to S3.

115, which is not described here, indicates a bank, and BH between banks means a bank hole. Light is emitted in an area opened through a bank hole, and the bank hole defines a light emitting part of each sub-pixel.

12 is a cross-sectional view illustrating a display device according to a second exemplary embodiment of the present invention.

As shown in FIG. 12 , the display device according to the second embodiment of the present invention applies the white organic light emitting device 2000 according to the second embodiment, and immediately before forming the first electrode 110, the light compensation layer 180 is formed. As such, the photocompensation layer 180 is also made of a transparent oxide electrode and has conductivity, and the photocompensation layer forming material and the first electrode forming material may be sequentially stacked and patterned using the same mask. In this case, the photo-compensation layer 180 may also function as the first electrode and directly connect to the drain electrode 106b of the thin film transistor through the contact hole CT.

Like the white organic light emitting device described above, the display device of the present invention includes a double stack having a short-wavelength light-emitting layer adjacent to an anode, which is an emitting-side electrode, and a plurality of long-wavelength light-emitting layers adjacent to a cathode, which is a counter electrode. Accordingly, the intensity of the EL spectrum at a specific wavelength does not decrease, and the luminous efficiency can be uniformly improved for each wavelength of red, green, and blue. That is, even if the organic stack in the white organic light emitting unit is configured by optimizing the green cavity, not only the green light emitting efficiency but also the blue light emitting efficiency is realized with the plurality of stacks, and the plurality of adjacent long-wavelength light emitting layers each have optimal light emitting efficiency. By adjusting the position to have , it is possible to increase the area where the outcoupling emittance spectrum curve and the PL spectrum overlap, thereby improving the luminous efficiency at all wavelengths. Therefore, white balance can be maintained.

In addition, the white organic light emitting device and the display device using the same of the present invention arrange a plurality of light emitting layers adjacent to the second electrode (cathode) as a green light emitting layer and a red light emitting layer, and the thickness of the emission side electrode is set to the first electrode (anode) By making the layer thicker than any other layer in the organic stack between the second electrode (cathode), the light extraction effect can be improved and the luminous efficiency can be improved. Accordingly, the luminance of the entire panel may be increased.

In addition, the display device of the present invention can obtain an even EL spectrum of red, green, and blue wavelengths, so that luminance can be improved in a panel such as a display device, and a color gamut can be expanded. there is.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be variously modified and implemented without departing from the technical spirit of the present invention. . Therefore, the various embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the various embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed according to the scope of the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: substrate 110: first electrode
123: first blue light emitting layer 130: first charge generating layer
142: second blue light emitting layer 150: second charge generating layer
162: red light emitting layer 163: green light emitting layer
170: second electrode 180: light compensation layer

Claims (14)

a transparent first electrode and a reflective second electrode facing the first electrode; and
It consists of an organic stack including a first light emitting stack, a first charge generation layer, a second light emitting stack, a second charge generation layer and a third light emitting stack sequentially disposed between the first electrode and the second electrode,
The first light emitting stack is in contact with the first electrode,
The first light emitting stack and the second light emitting stack each have a first blue light emitting layer and a second blue light emitting layer,
the first electrode is thicker than any layer in the organic stack;
The first electrode has a thickness of 2400 Å to 2700 Å. According to claim 1,
The third light-emitting stack includes a plurality of light-emitting layers emitting light of a longer wavelength than blue, and is in contact with the second electrode;
The first light-emitting stack has first and second organic common layers respectively contacting lower and upper surfaces of the first blue light-emitting layer;
The second light emitting stack has third and fourth organic common layers respectively in contact with lower and upper surfaces of the second blue light emitting layer,
The third light emitting stack includes fifth and sixth organic layers respectively contacting lower and uppermost surfaces of the plurality of light emitting layers. According to claim 2,
The plurality of light emitting layers of the third light emitting stack are stacked red light emitting layers and green light emitting layers,
The white organic light emitting device wherein the green light emitting layer is closer to the second electrode than the red light emitting layer. According to claim 3,
The first blue light emitting layer, the second blue light emitting layer, and the red light emitting layer each have a thickness of 100 Å to 400 Å,
The white organic light emitting device of claim 1 , wherein the green light emitting layer is thicker than the first blue light emitting layer, the second blue light emitting layer, and the red light emitting layer. According to claim 2,
The total thickness of the organic stack is 3500 Å to 3800 Å,
A distance between the first and second blue light emitting layers and a distance between the second blue light emitting layer and the lowermost surfaces of the plurality of light emitting layers of the third light emitting stack is 400 Å to 1200 Å.
delete According to claim 1,
The first electrode is a transparent oxide electrode including at least one of indium, titanium, zinc, tin, and gallium. According to claim 1,
The first electrode has a refractive index of 1.7 to 2.1. According to claim 8,
The white organic light emitting device further comprises a light compensation layer having a higher refractive index than the first electrode and electrically connected to the first electrode, on a surface of the first electrode not in contact with the organic stack. According to claim 9,
The combined thickness of the light compensation layer and the first electrode is 2400 Å to 2800 Å. According to claim 9,
The light compensation layer has a refractive index of 2.2 to 2.6. According to claim 9,
The light compensation layer is a transparent oxide electrode containing at least one of niobium, indium, titanium, zinc, tin, and gallium. a substrate having a plurality of sub-pixels;
a thin film transistor provided in each of the sub-pixels and connected to the first electrode of the white organic light emitting diode according to any one of claims 1 to 5 and 7 to 12; and
A display device including a color filter layer provided below the first electrode of at least one of the sub-pixels. According to claim 13,
The plurality of sub-pixels include a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel;
The color filter layer is divided into first to third color filters for the remaining sub-pixels except for the white sub-pixel, and is provided.