KR102272943B1 - White organic light emitting device - Google Patents

Abstract

The white organic light emitting diode according to the present invention includes a first light emitting part including a first light emitting layer between a first electrode and a second electrode, a second light emitting part including a second light emitting layer on the first light emitting part, and the second light emitting part. and a third light emitting part formed of a third light emitting layer on the portion, and at least one of the first light emitting layer and the third light emitting layer includes dopants doped at different ratios, thereby improving the efficiency of the light emitting layer and improving the lifespan of the device can do it

Description

White organic light emitting device {WHITE ORGANIC LIGHT EMITTING DEVICE}

The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device capable of improving the efficiency of a light emitting layer and improving the lifespan of the device.

Recently, as we enter the information age, the field of display that visually expresses electrical information signals has developed rapidly, and in response to this, various flat display devices with excellent performance such as thinness, light weight, and low power consumption (Flat Display) have been developed. device) is being developed.

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.

In particular, the organic light emitting diode display is a self-luminous device, and has advantages in that the response speed is fast and luminous efficiency, luminance, and viewing angle are large compared to other flat panel displays.

In the organic light emitting diode display, an organic light emitting layer is formed between two electrodes. Electrons and holes are respectively injected from the two electrodes into the organic light emitting layer to generate excitons according to the combination of electrons and holes. And, it is a device using the principle that light is generated when the generated exciton falls from an excited state to a ground state.

1. [White organic light emitting device] (Patent Application No. 10-2009-0092596)

Conventional organic light emitting devices have limitations in light emitting characteristics and lifespan performance due to the material and device structure of the organic light emitting layer, and various methods for improving the lifespan of the organic light emitting device have been proposed.

As one method, there is a method of using the light emitting layer as a single layer. In this method, a white organic light emitting device can be manufactured by using a single material or doping two or more materials. For example, there is a method in which red and green dopants are used in a blue host, or red, green, and blue dopants are added and used in a host material having a large band gap energy. However, this method has problems in that energy transfer to the dopant is incomplete and it is difficult to control the white balance.

In addition, there is a limit to the components of the dopant included in the light emitting layer due to the characteristics of the dopant itself. Also, since it is difficult to block the energy transfer between the dopants, there is a problem in that the luminous efficiency is lowered even when the doping concentration is adjusted.

As another method, there is a method in which two light emitting layers are stacked. However, this structure has problems in that there is a lot of energy transfer between the light emitting layers, and it is difficult to evenly distribute excitons in each light emitting layer, so that it is difficult to obtain high luminous efficiency.

In addition, when one dopant and one host are applied to the emission layer, there is a problem in that luminous efficiency and lifetime of the device cannot be improved at the same time. That is, depending on the material of the dopant or the host, there is a problem that the luminous efficiency is improved but the lifespan of the device is reduced, and the lifespan of the device is improved but the luminous efficiency is lowered.

In addition, the organic light emitting device does not emit light in the entire region of the light emitting layer, but strongly emits light due to recombination occurring at a point where electrons and holes meet each other. Therefore, the luminous efficiency can be improved only when the recombination region is reflected in the design of the organic light emitting diode. However, there is a limit in designing the light emitting region, which is the recombination region, as a desired region in consideration of the characteristics of the light emitting layer.

Accordingly, the inventors of the present invention recognized the above-mentioned problems and conducted various experiments to improve the lifespan of the device. Through various experiments, a white organic light emitting device having a new structure in which the light emitting area of the light emitting layer is improved, the light emitting efficiency is not reduced, and the lifespan of the device can be improved was invented.

An object to be solved according to an embodiment of the present invention is to provide a white organic light emitting device capable of improving the efficiency of a light emitting layer and improving the lifespan of the device.

The problems to be solved according to the embodiment of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A white organic light emitting diode according to an embodiment of the present invention includes a first light emitting part including a first light emitting layer between a first electrode and a second electrode, a second light emitting part including a second light emitting layer on the first light emitting part, and the By including a third light emitting part consisting of a third light emitting layer on the second light emitting part, and at least one of the first light emitting layer and the third light emitting layer includes dopants doped at different ratios, the efficiency of the light emitting layer can be improved, Provided is a white organic light emitting device capable of improving the lifespan of the device.

The first light emitting layer may be one of a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

The second light emitting layer may be composed of a yellow-green light emitting layer or a green light emitting layer.

The third light emitting layer may be one of a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

A ratio of the dopant included in the first emission layer increases from the second electrode to the first electrode.

The ratio of the dopant included in the first light emitting layer may be in the range of 2% to 10%.

A ratio of the dopant included in the third emission layer increases from the first electrode to the second electrode.

The ratio of the dopant included in the third emission layer may be in the range of 2% to 10%.

The details of other embodiments are included in the detailed description and drawings.

In the present invention, by configuring dopants included in the light emitting layer with dopants doped at different ratios, the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

In addition, since the light emitting area of the light emitting layer is made in the entire area of the light emitting layer by dopants doped at different ratios, there is an effect of improving the efficiency of the light emitting layer and improving the lifespan of the device.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

Since the content of the invention described in the problems to be solved above, the means for solving the problems, and the effects do not specify the essential characteristics of the claims, the scope of the claims is not limited by the matters described in the content of the invention.

1 is a schematic cross-sectional view illustrating a white organic light emitting diode according to an embodiment of the present invention.
2 is a schematic cross-sectional view illustrating a white organic light emitting diode according to another exemplary embodiment of the present invention.
3 is a schematic cross-sectional view illustrating a white organic light emitting diode according to another embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are exemplary, and thus the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless otherwise explicitly stated.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between the two parts unless 'directly' is used.

In the case of a description of a temporal relationship, for example, 'immediately' or 'directly' when a temporal relationship is described with 'after', 'following', 'after', 'before', etc. It may include cases that are not continuous unless this is used.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

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

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and examples.

1 is a schematic cross-sectional view illustrating a white organic light emitting diode according to an embodiment of the present invention.

The white organic light emitting diode 100 illustrated in FIG. 1 is a schematic diagram illustrating different configurations of dopant ratios of the first light emitting layer included in the first light emitting part.

The white organic light emitting device 100 includes a first electrode 102 and a second electrode 104 on a substrate 101 , and a first light emitting unit 110 and a second light emitting unit between the first and second electrodes 102 and 104 . The light emitting unit 120 and the third light emitting unit 130 are configured.

The first electrode 102 is an anode for supplying holes, and may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), etc., which are transparent conductive materials such as transparent conductive oxide (TCO), but it must be It is not limited.

The second electrode 104 is a cathode for supplying electrons, and is formed of a metallic material such as gold (Au), silver (Ag), aluminum (Al), molybdenum (Mo), magnesium (Mg), or the like, or It may be formed of an alloy, but is not necessarily limited thereto.

The first electrode 102 and the second electrode 104 may be referred to as an anode or a cathode, respectively. In addition, the first electrode 102 may be referred to as a transflective electrode, and the second electrode 104 may be referred to as a reflective electrode.

Here, a bottom emission method in which the first electrode 102 is a transflective electrode and the second electrode 104 is a reflective electrode will be described.

The first light emitting unit 110 includes a first hole transporting layer (HTL) 112, a first emitting layer (EML) 114 and a first electron transporting layer (HTL) on the first electrode 102. It may include an Electron Transporting Layer (ETL) 116 .

Although not shown in the drawings, the first light emitting unit 110 may additionally include a hole injection layer (HIL). The hole injection layer HIL is formed on the first electrode 102 and serves to smoothly inject holes from the first electrode 102 . The first hole transport layer (HTL) 112 supplies holes from the hole injection layer (HIL) to the first emission layer (EML) 114 . The first electron transport layer (ETL) 116 supplies electrons from the first charge generation layer (CGL) 140 to the first emission layer (EML) 114 .

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

In the first emission layer (EML) 114 , holes supplied through the first hole transport layer (HTL) 112 and electrons supplied through the first electron transport layer (ETL) 116 recombine So light is generated.

The first hole transport layer (HTL) 112 may be formed by applying two or more layers or two or more materials. The first hole transport layer (HTL) 112 is N,N-dinaphthyl-N,N'-diphenylbenzidine (NPD), N,N'-bis-(3-methylphenyl)-N,N'-bis- (phenyl)-benzidine), s-TAD and MTDATA (4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine) may consist of any one or more selected from the group consisting of However, the present invention is not limited thereto.

The first electron transport layer (ETL) 116 may be formed by applying two or more layers or two or more materials. The first electron transport layer (ETL) 116 is tris(8-hydroxyquinolino) aluminum (Alq3), PBD, TAZ, spiro-PBD, BAlq, lithium quinolate (Liq), BMB-3T, PF-6P, TPBI, COT. And it may consist of any one or more selected from the group consisting of SAlq, but is not limited thereto.

A first charge generation layer (CGL) 140 may be further formed between the first light emitting unit 110 and the second light emitting unit 120 . The first charge generation layer (CGL) 140 adjusts the charge balance between the first light emitting unit 110 and the second light emitting unit 120 . The first charge generation layer 140 may include an N-type charge generation layer (N-CGL) and a P-type charge generation layer (P-CGL).

The N-type charge generation layer (N-CGL) is an alkali metal such as lithium (Li), sodium (Na), potassium (K), or cesium (Cs), or magnesium (Mg), strontium (Sr), barium ( Ba) or an organic layer doped with an alkaline earth metal such as radium (Ra), but is not necessarily limited thereto.

The P-type charge generation layer (P-CGL) may be formed of an organic layer including a P-type dopant, but is not limited thereto.

In addition, the first charge generating layer (CGL) 140 may be formed as a single layer.

The first light emitting layer (EML) 114 of the first light emitting unit 110 may be formed of a blue light emitting layer. The first light emitting layer (EML) 114 may include a deep blue light emitting layer or a sky blue light emitting layer in addition to a blue light emitting layer. An emission peak of the emission region of the first emission layer (EML) 114 may be in a range of 440 nm to 480 nm.

The second light emitting unit 120 includes a second hole transporting layer (HTL) 122 , a second emitting layer (EML) 124 , and a second electron transporting layer (ETL) 126 . ) can be included.

Although not shown in the drawings, the second light emitting unit 120 may further include an electron injection layer (EIL) on the second electron transport layer (ETL) 126 . In addition, the second light emitting unit 120 may be configured to additionally include a hole injection layer (HIL).

The second hole transport layer (HTL) 122 may be made of the same material as the first hole transport layer (HTL) 112 , but is not limited thereto.

The second hole transport layer (HTL) 122 may be formed by applying two or more layers or two or more materials.

The second electron transport layer (ETL) 126 may be made of the same material as the first electron transport layer (ETL) 116 , but is not limited thereto.

The second electron transport layer (ETL) 126 may be formed by applying two or more layers or two or more materials.

The second light emitting layer (EML) 124 of the second light emitting unit 120 may include a yellow-green light emitting layer or a green light emitting layer. An emission peak of the emission region of the second emission layer (EML) 124 may be in a range of 510 nm to 580 nm.

The third light emitting unit 130 includes a third electron transporting layer (ETL) 136 , a third emitting layer (EML) 134 , and a third hole transporting layer under the second electrode 104 . (HTL; Hole Transporting Layer) 132 may be included.

Although not shown in the drawings, the third light emitting part 130 may be configured to further include an electron injection layer (EIL) on the third electron transport layer (ETL) 136 . In addition, it may be configured to further include a hole injection layer (HIL; Hole Injecting Layer).

The third hole transport layer (HTL) 132 is TPD (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-bi-phenyl-4,4'-diamine) or It may be made of NPB (N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine), but is not necessarily limited thereto.

The third hole transport layer (HTL) 132 may be formed by applying two or more layers or two or more materials.

The third electron transport layer (ETL) 136 may be made of oxadiazole, triazole, phenanthroline, benzoxazole or benzthiazole, etc. It is not necessarily limited to this.

The third electron transport layer (ETL) 136 may be formed by applying two or more layers or two or more materials.

A second charge generation layer (CGL) 150 may be further formed between the second light emitting unit 120 and the third light emitting unit 130 . The second charge generation layer 150 adjusts the charge balance between the second light emitting unit 120 and the third light emitting unit 130 . The second charge generation layer (CGL) 150 may include an N-type charge generation layer (N-CGL) and a P-type charge generation layer (P-CGL).

The N-type charge generation layer (N-CGL) serves to inject electrons into the second light-emitting unit 120 , and the P-type charge generation layer (P-CGL) serves as the third light-emitting unit 130 . It serves to inject holes. The present invention is not limited thereto, and the second charge generating layer (CGL) 150 may be formed as a single layer.

The N-type charge generation layer (N-CGL) is an alkali metal such as lithium (Li), sodium (Na), potassium (K), or cesium (Cs), or magnesium (Mg), strontium (Sr), barium ( Ba) or an organic layer doped with an alkaline earth metal such as radium (Ra), but is not necessarily limited thereto.

The P-type charge generation layer (P-CGL) may be formed of an organic layer including a P-type dopant, but is not limited thereto. The first charge generation layer (CGL) 140 is made of the same material as the N-type charge generation layer (N-CGL) of the second charge generation layer (CGL) 150 and the P-type charge generation layer (P-CGL) may be made, but is not necessarily limited thereto.

The third light emitting layer (EML) 134 of the third light emitting unit 130 may be formed of a blue light emitting layer. The third light emitting layer (EML) 134 may include a deep blue light emitting layer or a sky blue light emitting layer in addition to the blue light emitting layer. An emission peak of the emission region of the third emission layer (EML) 134 may be in a range of 440 nm to 480 nm.

1 , the first emission layer (EML) 114 has different ratios of dopants included in the first emission layer (EML) 114 . That is, the first light emitting layer (EML) 114 having a first dopant 114a , a second dopant 114b , and a third dopant 114c is formed. The ratio of the first dopant 114a , the second dopant 114b , and the third dopant 114c ranges from 2% to 10% based on the volume of the first light emitting layer (EML) 114 .

The host of the first emission layer (EML) 114 may include an anthracene derivative, for example, TBSA (9,10-bis[(2",7"-di-t-butyl)-9). ',9"-spirobifluorenyl]anthracene), 1-ADN (9,10-di(2-naphyhyl)anthracene) may be used, but is not limited thereto.

In addition, the first dopant 114a , the second dopant 114b , and the third dopant 114c may include an anthracene derivative, a perylene derivative, or a pyrene derivative. It is not limited. Alternatively, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and PPV-based polymers, The present invention is not limited thereto.

In addition, the first dopant 114a , the second dopant 114b , and the third dopant 114c may be formed of the same material, but are not limited thereto.

In addition, the first dopant 114a , the second dopant 114b , and the third dopant 114c may be formed of the same material, and the dopant ratio may be different.

A method of forming the first light emitting layer (EML) 114 will be described as an example. The first emission layer (EML) 114 includes two hosts and one dopant. The apparatus for forming the first light emitting layer (EML) 114 includes a first deposition source and a second deposition source for depositing the two host materials on a substrate, and a third deposition source for depositing a dopant material. is composed The first deposition source, the second deposition source, and the third deposition source are configured as linear sources. The linear source is a method of performing a deposition process by ejecting a deposition material while a linear source moves. As the first deposition source and the second deposition source move, the ratio of the dopant may be adjusted by controlling the two host materials.

An experiment was conducted with a case in which the ratio of the dopant included in the first emission layer (EML) 114 increases toward the first electrode 102 and decreases toward the first electrode 102 .

Table 1 below shows the results of measuring lifetime and efficiency, which are experimental results.

In Table 1, in the comparative example, the ratio of the dopant included in the first light emitting layer (EML) 114 is a constant ratio, and the ratio is 5%.

In Example 1, the ratio of the first dopant 114a included in the first light emitting layer (EML) 114 is 7%, the ratio of the second dopant 114b is 5%, and the ratio of the third dopant 114c is It is made up of 3%. That is, in Example 1, the ratio of the dopant increases toward the first electrode 102 .

In Example 2, the ratio of the first dopant 114a included in the first light emitting layer (EML) 114 is 3%, the ratio of the second dopant 114b is 5%, and the ratio of the third dopant 114c is It is made up of 7%. That is, in Example 2, the dopant ratio is configured to decrease toward the first electrode 102 .

Although the ratio of the dopant in Examples 1 and 2 was 3%, 5%, and 7%, the ratio of the dopant is not limited thereto, and the ratio of the dopant may be configured within the range of 2% to 10%. For example, the ratio of the first dopant 114a may be 2%, the ratio of the second dopant 114b may be 4%, and the ratio of the third dopant 114c may be 6%.

The results in Table 1 compare Examples 1 and 2 when the lifetime and efficiency of the Comparative Example are 100%.

As shown in Table 1, it can be seen that Examples 1 and 2 are maintained compared to Comparative Examples in terms of efficiency. That is, it can be seen that there is no change in efficiency according to the ratio of the dopant. Therefore, it can be seen that the existing problems in that the efficiency is lowered depending on the dopant or the material of the host or the efficiency is lowered depending on the ratio of the dopant does not occur.

And, in terms of life, it can be seen that Example 1 is improved by about 18% compared to Comparative Example. Accordingly, it can be seen that when the ratio of the dopant included in the first light emitting layer (EML) 114 increases toward the first electrode 102 , the lifespan of the device is improved.

Accordingly, it can be seen that, when the ratio of the dopant is configured differently according to another embodiment of the present invention, the efficiency is maintained and the lifespan of the device is improved.

In the comparative example, the emission region of the first emission layer (EML) 114 is biased toward the first electron transport layer (ETL) 116 . In Example 1, by configuring the ratio of the first dopant 114a adjacent to the first hole transport layer (HTL) 112 to be greater than the ratio of the second dopant 114b and the third dopant 114c, holes are formed A large amount of excitons combined with electrons are formed in the first light emitting layer (EML) 114 . And, by configuring the ratio of the first dopant 114a adjacent to the first hole transport layer (HTL) 112 to be greater than the ratio of the second dopant 114b and the third dopant 114c, the first light emitting layer EML ) 114 moves from the first electron transport layer (ETL) 116 to the first hole transport layer (HTL) 112 . Accordingly, since the light emitting area of the first light emitting layer (EML) 114 becomes the entire area of the first light emitting layer (EML) 114 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

In addition, in consideration of the distance from the second electrode 104 to the first light emitting layer (EML) 114 , electrons from the second electrode 104 are included in the first light emitting layer (EML) 114 . It is configured such that the doping amount increases toward the first electrode 102 so as to be transferred to the dopant. Accordingly, since the light emitting area of the first light emitting layer (EML) 114 becomes the entire area of the first light emitting layer (EML) 114 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

The white organic light emitting diode according to an embodiment of the present invention may be applied to a bottom emission method, a top emission method, or a dual emission method.

Also, although not shown, in the organic light emitting diode display including the organic light emitting diode according to the exemplary embodiment of the present invention, a gate line and a data line defining each pixel area crossing each other on a substrate and parallel to any one of them An extended power supply line is positioned, and a switching thin film transistor connected to a gate line and a data line and a driving thin film transistor connected to the switching thin film transistor are positioned in each pixel area. The driving thin film transistor is connected to the first electrode 102 .

2 is a schematic cross-sectional view illustrating a white organic light emitting diode according to another exemplary embodiment of the present invention. In describing the present embodiment, a description of the same or corresponding components as in the previous embodiment will be omitted.

The white organic light emitting diode 200 illustrated in FIG. 2 is a diagram illustrating different configurations of dopants included in the third light emitting layer of the third light emitting part.

In another embodiment of the present invention, the white organic light emitting device 200 includes a first electrode 202 and a second electrode 204 on a substrate 201 , and a first light emitting part between the first and second electrodes 202 and 204 . 210 , a second light emitting unit 220 , and a third light emitting unit 230 are configured.

Here, a bottom emission method in which the first electrode 202 is a transflective electrode and the second electrode 204 is a reflective electrode will be described.

The first light emitting part 210 may include a first hole transport layer (HTL) 212 , a first emission layer (EML) 214 , and a first electron transport layer (ETL) 216 . Although not shown in the drawings, a hole injection layer HIL may be additionally formed on the first electrode 202 . The first light emitting layer (EML) 214 may include a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

The second light emitting part 220 may include a second hole transport layer (HTL) 222 , a second emission layer (EML) 224 , and a second electron transport layer (ETL) 226 . Although not shown in the drawings, an electron injection layer (EIL) may be additionally formed on the second electron transport layer (ETL) 226 . In addition, a hole injection layer (HIL) may be additionally configured. The second emission layer (EML) 224 may include a yellow-green emission layer or a green emission layer.

A first charge generating layer (CGL) 240 may be formed between the first light emitting unit 210 and the second light emitting unit 220 .

The third light emitting part 230 may include a third hole transport layer (HTL) 232 , a third emission layer (EML) 234 , and a third electron transport layer (ETL) 236 . Although not shown in the drawings, an electron injection layer (EIL) may be additionally formed on the third electron transport layer (ETL) 236 . In addition, a hole injection layer (HIL) may be additionally configured.

In addition, a second charge generating layer (CGL) 250 may be formed between the second light emitting unit 220 and the third light emitting unit 230 .

The first light emitting unit 210 , the second light emitting unit 220 , and the third light emitting unit 230 are the same or corresponding components as in the previous embodiment, and thus will be omitted.

In addition, the ratio of the dopant included in the third light emitting layer (EML) 234 of the third light emitting part 230 is configured differently. That is, the third light emitting layer (EML) 234 having a first dopant 234a , a second dopant 234b , and a third dopant 234c is formed. The third light emitting layer (EML) 234 may include a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

The proportion of the dopant is in the range of 2% to 10% based on the volume of the third light emitting layer (EML) 234 .

The host of the third emission layer (EML) 234 may include an anthracene derivative, for example, TBSA (9,10-bis[(2",7"-di-t-butyl)-9). ',9"-spirobifluorenyl]anthracene), 1-ADN (9,10-di(2-naphyhyl)anthracene) may be used, but is not limited thereto.

In addition, the first dopant 234a , the second dopant 234b , and the third dopant 234c may include an anthracene derivative, a perylene derivative, or a pyrene derivative. It is not limited. Alternatively, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and PPV-based polymers, However, the present invention is not limited thereto.

In addition, the first dopant 234a , the second dopant 234b , and the third dopant 234c may be formed of the same material, but are not limited thereto.

In addition, the first dopant 234a , the second dopant 234b , and the third dopant 234c may be formed of the same material, and the dopant ratio may be different.

A method of forming the third light emitting layer (EML) 234 will be described as an example. The third emission layer (EML) 234 includes two hosts and one dopant. The apparatus for forming the third light emitting layer (EML) 234 includes a first deposition source and a second deposition source for depositing the two host materials on a substrate, and a third deposition source for depositing a dopant material. is composed The first deposition source, the second deposition source, and the third deposition source are configured as linear sources. The linear source is a method of performing a deposition process by ejecting a deposition material while a linear source moves. As the first deposition source and the second deposition source move, the ratio of the dopant may be adjusted by controlling the two host materials.

An experiment was conducted with a case in which the ratio of the dopant included in the third light emitting layer (EML) 234 increases toward the second electrode 204 and decreases toward the second electrode 204 .

Table 2 below shows the results of measuring life and efficiency, which are experimental results.

In Table 2, in the comparative example, the ratio of the dopant included in the third light emitting layer (EML) 234 is a constant ratio, and the ratio is 5%.

In Example 3, the ratio of the first dopant 234a included in the third light emitting layer (EML) 234 is 7%, the ratio of the second dopant 234b is 5%, and the ratio of the third dopant 234c is It is made up of 3%. And, in Example 3, the dopant ratio is configured to decrease toward the second electrode 204 .

In Example 4, the ratio of the first dopant 234a included in the third light emitting layer (EML) 234 is 3%, the ratio of the second dopant 234b is 5%, and the ratio of the third dopant 234c is It is made up of 7%. And, in Example 4, the dopant ratio is configured to increase toward the second electrode 204 .

Although the ratio of the dopant in Examples 3 and 4 was 3%, 5%, and 7%, the proportion of the dopant may be configured within the range of 2% to 10% without being limited thereto. For example, the ratio of the first dopant 234a may be 2%, the ratio of the second dopant 234b may be 4%, and the ratio of the third dopant 234c may be 6%.

The results in Table 2 compare Examples 3 and 4 when the lifetime and efficiency of the Comparative Example are 100%.

As shown in Table 2, it can be seen that Examples 3 and 4 are maintained compared to Comparative Examples in terms of efficiency. That is, it can be seen that there is no change in efficiency according to the ratio of the dopant. Accordingly, it can be seen that there is no existing problem that the efficiency is lowered depending on the dopant or the host material or the efficiency is lowered depending on the ratio of the dopant.

And, in terms of life, it can be seen that Example 4 is improved by about 20% compared to the comparative example. Accordingly, it can be seen that when the ratio of the dopant included in the third light emitting layer (EML) 234 increases toward the second electrode 204, the lifespan of the device is improved.

Accordingly, it can be seen that, when the ratio of the dopant is configured differently according to another embodiment of the present invention, the efficiency is maintained and the lifespan of the device is improved.

In the comparative example, the light emitting region of the third light emitting layer (EML) 234 is formed at the interface with the third hole transport layer (HTL) 232 . In the fourth embodiment, by configuring the ratio of the third dopant 234c adjacent to the third electron transport layer (HTL) 236 to be greater than the ratio of the first dopant 234a and the second dopant 234b, the third light emitting layer The emission region of the (EML) 234 moves from the interface of the third hole transport layer (HTL) 232 to the central region. Therefore, since the interfacial deterioration phenomenon between the third hole transport layer (HTL) 232 and the third light emitting layer (EML) 234 is prevented, the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved. have.

In addition, by configuring the ratio of the third dopant 234c adjacent to the third electron transport layer (ETL) 236 to be greater than the ratio of the first dopant 234a and the second dopant 234b, the third light emitting layer (EML) ) 234 is formed in the entire area of the third light emitting layer (EML) 234 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

The white organic light emitting diode according to another embodiment of the present invention may be applied to a bottom emission method, a top emission method, or a dual emission method.

Also, although not shown, in an organic light emitting diode display including an organic light emitting diode according to another exemplary embodiment of the present invention, a gate line and a data line defining each pixel area crossing each other on a substrate and parallel to any one of them An extended power supply line is positioned, and a switching thin film transistor connected to a gate line and a data line and a driving thin film transistor connected to the switching thin film transistor are positioned in each pixel area. The driving thin film transistor is connected to the first electrode 202 .

3 is a schematic cross-sectional view illustrating a white organic light emitting diode according to another embodiment of the present invention. In describing the present embodiment, a description of the same or corresponding components as in the previous embodiment will be omitted.

The white organic light emitting diode 300 illustrated in FIG. 3 is a diagram illustrating different configurations of dopants included in the first light emitting part and the third light emitting part.

A white organic light emitting diode 300 according to another embodiment of the present invention includes a first electrode 302 and a second electrode 304 on a substrate 301 , and a first electrode 302 and a second electrode 304 between the first and second electrodes 302 and 304 . A first light emitting unit 310 , a second light emitting unit 320 , and a third light emitting unit 330 are configured.

Here, a bottom emission method in which the first electrode 302 is a transflective electrode and the second electrode 304 is a reflective electrode will be described.

The first light emitting part 310 may include a first hole transport layer (HTL) 312 , a first emission layer (EML) 314 , and a first electron transport layer (ETL) 316 . Although not shown in the drawing, a hole injection layer HIL may be additionally formed on the first electrode 302 . The first light emitting layer (EML) 314 may include a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

The second light emitting part 320 may include a second hole transport layer (HTL) 322 , a second emission layer (EML) 324 , and a second electron transport layer (ETL) 326 . Although not shown in the drawings, an electron injection layer (EIL) may be additionally formed on the second electron transport layer (ETL) 326 . In addition, a hole injection layer (HIL) may be additionally configured. The second emission layer (EML) 324 may include a yellow-green emission layer or a green emission layer.

In addition, a first charge generation layer (CGL) 340 may be formed between the first light emitting unit 310 and the second light emitting unit 320 .

The third light emitting part 330 may include a third hole transport layer (HTL) 332 , a third emission layer (EML) 334 , and a third electron transport layer (ETL) 336 . Although not shown in the drawings, an electron injection layer (EIL) may be additionally formed on the third electron transport layer (ETL) 336 . In addition, a hole injection layer (HIL) may be additionally configured. The third light emitting layer (EML) 334 may include a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer.

A second charge generation layer (CGL) 350 may be formed between the second light emitting unit 320 and the third light emitting unit 330 .

The first light emitting unit 310 , the second light emitting unit 320 , and the third light emitting unit 330 are the same or corresponding components as in the previous embodiment, and thus will be omitted.

In addition, ratios of dopants included in the first light emitting layer (EML) 314 and the third light emitting layer (EML) 334 of the first light emitting unit 310 and the third light emitting unit 330 are configured differently.

That is, the first light emitting layer (EML) 314 having a first dopant 314a , a second dopant 314b , and a third dopant 314c is formed. The third light emitting layer (EML) 334 having a first dopant 334a , a second dopant 334b , and a third dopant 334c is formed. The ratio of the dopant is in the range of 2% to 10% based on the volume of the first emission layer (EML) 314 and the third emission layer (EML) 334 .

The host of the first emission layer (EML) 314 and the third emission layer 334 may include an anthracene derivative, for example, TBSA (9,10-bis[(2",7"-) di-t-butyl)-9',9"-spirobifluorenyl]anthracene) and 1-ADN (9,10-di(2-naphyhyl)anthracene) may be used, but the present invention is not limited thereto.

In addition, the first dopant 314a , the second dopant 314b , and the third dopant 314c may include an anthracene derivative, a perylene derivative, or a pyrene derivative. It is not limited. Alternatively, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and PPV-based polymers, However, the present invention is not limited thereto. In addition, the first dopant 314a , the second dopant 314b , and the third dopant 314c of the first light emitting layer (EML) 314 may be formed of the same material, but are not limited thereto.

In addition, the first dopant 334a , the second dopant 334b , and the third dopant 334c may include an anthracene derivative, a perylene derivative, or a pyrene derivative. It is not limited. Alternatively, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and PPV-based polymers, However, the present invention is not limited thereto. Also, the first dopant 334a , the second dopant 334b , and the third dopant 334c of the third light emitting layer (EML) 334 may be formed of the same material, but are not limited thereto.

A method of forming the first light emitting layer (EML) 314 and the third light emitting layer (EML) 334 will be described as an example. The first emission layer (EML) 314 and the third emission layer (EML) 334 include two hosts and one dopant. The apparatus for forming the first light emitting layer (EML) 314 and the third light emitting layer (EML) 334 includes a first deposition source and a second deposition source for depositing the two host materials on a substrate; and a third deposition source for depositing a dopant material. The first deposition source, the second deposition source, and the third deposition source are configured as linear sources. The linear source is a method of performing a deposition process by ejecting a deposition material while a linear source moves. As the first deposition source and the second deposition source move, the ratio of the dopant may be adjusted by controlling the two host materials.

In the first light emitting layer (EML) 314 , the ratio of the first dopant 314a adjacent to the first hole transport layer (HTL) 312 is greater than the ratio of the second dopant 314b and the third dopant 314c. By configuring, many excitons in which holes and electrons are combined are formed in the first light emitting layer (EML) 314 . In addition, by configuring the ratio of the first dopant 314a adjacent to the first hole transport layer (HTL) 312 to be greater than that of the second dopant 314b and the third dopant 314c, the first light emitting layer (EML) ) 314 moves from the first electron transport layer (ETL) 316 to the first hole transport layer (HTL) 312 . Accordingly, since the light emitting area of the first light emitting layer (EML) 314 becomes the entire area of the first light emitting layer (EML) 314 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

In addition, in consideration of the distance from the second electrode 304 to the first light emitting layer (EML) 314 , electrons from the second electrode 304 are included in the first light emitting layer (EML) 314 . It is configured such that the doping amount increases toward the first electrode 302 so as to be transferred to the dopant. Accordingly, since the light emitting area of the first light emitting layer (EML) 314 becomes the entire area of the first light emitting layer (EML) 314 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

In the third light emitting layer (EML) 334 , the ratio of the third dopant 334c adjacent to the third electron transport layer (HTL) 336 is greater than the ratio of the first dopant 334a and the second dopant 334b. By configuring, the light emitting region of the third light emitting layer (EML) 334 moves from the interface of the third hole transport layer (HTL) 332 to the central region. Accordingly, since the interfacial deterioration phenomenon between the third hole transport layer (HTL) 332 and the third light emitting layer (EML) 334 is prevented, the efficiency of the light emitting layer can be improved, and the lifespan of the device can be improved. have.

In addition, by configuring the ratio of the third dopant 334c adjacent to the third electron transport layer (ETL) 336 to be greater than the ratio of the first dopant 334a and the second dopant 334b, the third light emitting layer (EML) ) 334 is formed in the entire area of the third light emitting layer (EML) 334 , the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

The white organic light emitting diode according to another embodiment of the present invention may be applied to a bottom emission method, a top emission method, or a dual emission method.

Also, although not shown, in an organic light emitting diode display including an organic light emitting diode according to another exemplary embodiment of the present invention, a gate line and a data line that cross each other on a substrate and define each pixel area, and are parallel to any one of them A power supply line extending to the top is located, and a switching thin film transistor connected to a gate line and a data line and a driving thin film transistor connected to the switching thin film transistor are located in each pixel area. The driving thin film transistor is connected to the first electrode 302 .

As described above, in the present invention, by configuring the dopants included in the light emitting layer with dopants doped at different ratios, the efficiency of the light emitting layer can be improved and the lifespan of the device can be improved.

In addition, since the light emitting area of the light emitting layer is formed in the entire area of the light emitting layer by dopants doped at different ratios, there is an effect of improving the efficiency of the light emitting layer and improving the lifespan of the device.

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 various modifications may be made within the scope without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by 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, 200, 300: white organic light emitting device
101, 201, 301: substrate 102, 202, 302: first electrode
104, 204, 304: second electrode 110, 210, 310: first light emitting part
120, 220, 320: second light-emitting unit 130, 230, 330: third light-emitting unit
140, 240, 340: first charge generation layer 150, 250, 350: second charge generation layer
112, 212, 312: first hole transport layer 122, 222, 322: second hole transport layer
132, 232, 332: third hole transport layer 116, 216, 316: first electron transport layer
126, 226, 326: second electron transport layer 136, 236, 336: third electron transport layer
114, 214, 314: first light emitting layer
124, 224, 324: second light emitting layer
134, 234, 334: third light emitting layer

Claims (10)

a first light emitting part including a first light emitting layer between the first electrode and the second electrode;
a second light emitting unit including a second light emitting layer on the first light emitting unit; and
and a third light emitting unit including a third light emitting layer on the second light emitting unit,
The white organic light-emitting device, characterized in that the ratio of the dopant included in the first emission layer increases from the second electrode to the first electrode. The method of claim 1,
The first light emitting layer is a white organic light emitting device, characterized in that one of a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer. The method of claim 1,
The second light-emitting layer is a white organic light-emitting device, characterized in that composed of a yellow-green light-emitting layer or a green light-emitting layer. The method of claim 1,
The third light emitting layer is a white organic light emitting device, characterized in that one of a blue light emitting layer, a deep blue light emitting layer, or a sky blue light emitting layer. delete The method of claim 1,
A white organic light-emitting device, characterized in that the ratio of the dopant included in the first light-emitting layer is in the range of 2% to 10%. The method of claim 1,
The white organic light emitting device, characterized in that the ratio of the dopant included in the third light emitting layer increases from the first electrode to the second electrode. 8. The method of claim 7,
A white organic light-emitting device, characterized in that the ratio of the dopant included in the third light-emitting layer is in the range of 2% to 10%. a first light emitting part including a first light emitting layer between the first electrode and the second electrode;
a second light emitting unit including a second light emitting layer on the first light emitting unit; and
and a third light emitting unit including a third light emitting layer on the second light emitting unit,
The white organic light emitting device, characterized in that the ratio of the dopant included in the third light emitting layer increases from the first electrode to the second electrode. 10. The method of claim 9,
A white organic light-emitting device, characterized in that the ratio of the dopant included in the third light-emitting layer is in the range of 2% to 10%.

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