KR101373370B1 - Organic light emitting diodes device and method of fabricating the same - Google Patents

Abstract

The present invention relates to an organic light emitting diode device and a method of manufacturing the organic light emitting diode device further comprises an auxiliary light emitting layer between the first charge transport layer and the organic light emitting layer, by moving the main light emitting region to the interface between the auxiliary light emitting layer and the organic light emitting layer In addition to improving the luminous efficiency and lifetime of the organic light emitting diode device, the color coordinates could be improved.

Luminous Efficiency, Lifetime, Color Coordinates, Secondary Light Emitting Layer, Host

Description

Organic light emitting diode device and its manufacturing method {ORGANIC LIGHT EMITTING DIODES DEVICE AND METHOD OF FABRICATING THE SAME}

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

2 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode device according to a first experimental example.

3 is a cross-sectional view of an organic light emitting layer showing a formation position of a doped layer among various organic light emitting diode devices manufactured by the manufacturing method according to the first experimental example.

FIG. 4 is a diagram illustrating light emission efficiencies of organic light emitting diode devices in which a doped layer is changed in an organic light emitting layer.

FIG. 5 is a view illustrating emission spectra of organic light emitting diode devices manufactured according to Examples 2 and 4 and Comparative Examples. FIG.

      DESCRIPTION OF THE REFERENCE NUMERALS (S)

 100 substrate 110 first electrode

 120: first charge injection layer 130: first charge transport layer

 140: auxiliary light emitting layer 150: organic light emitting layer

 160: second charge transport layer 170: second charge injection layer

 180: second electrode

The present invention relates to an organic light emitting diode device and a method for manufacturing the same, and more particularly to an organic light emitting diode device and a method for manufacturing the same that can improve the characteristics.

Recently, as the size of the display device increases, the demand for a flat display device having less space is increasing. As one of the flat display devices, the technology of the organic light emitting diode device is rapidly developing.

The organic light emitting diode device basically has an organic light emitting layer interposed between the anode and the cathode. At this time, when a forward voltage is applied to the organic light emitting diode, holes and electrons are injected into the organic light emitting layer from the anode and the cathode, respectively. Holes and electrons injected from the organic light emitting layer recombine to form excitons having high energy, and the excitons fall to a ground state (ie, low energy) to generate light.

Thus, unlike the liquid crystal display, the organic light emitting diode device generates light by itself without providing a backlight, thereby providing an image to a user. As a result, the organic light emitting diode can be manufactured to be light and thin, and the manufacturing cost can be reduced. In addition, the organic light emitting diode device can be applied to a flexible display.

However, organic light emitting diode devices have many improvements, such as low luminous efficiency, short lifetime, and low color coordinates, compared to the liquid crystal display device.

An object of the present invention is to provide an organic light emitting diode device that can improve the luminous efficiency, lifetime and color coordinates at the same time.

Still another object of the present invention is to provide a method of manufacturing the organic light emitting diode device.

One aspect of the present invention to achieve the above technical problem provides an organic light emitting diode device. The organic light emitting diode device includes a first electrode, a first charge injection layer disposed on the first electrode, a first charge transport layer disposed on the first charge injection layer, and an auxiliary light emitting layer disposed on the first charge transport layer, An organic light emitting layer disposed on the auxiliary light emitting layer and having a higher luminous efficiency than the auxiliary light emitting layer, and a second electrode disposed on the organic light emitting layer.

Another aspect of the present invention to achieve the above technical problem provides a method of manufacturing an organic light emitting diode device. The manufacturing method comprises the steps of forming a first electrode on a substrate, forming a first charge injection layer on the first electrode, forming a first charge transport layer on the first charge injection layer, and the first Forming an auxiliary light emitting layer on the charge transport layer, forming an organic light emitting layer having a higher luminous efficiency than the auxiliary light emitting layer on the auxiliary light emitting layer, and forming a second electrode on the organic light emitting layer.

Hereinafter, with reference to the drawings of the organic light emitting diode device according to the present invention will be described in detail. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of an apparatus may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

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

Referring to FIG. 1, the organic light emitting diode device includes a first electrode 110, a second electrode 180, and an organic light emitting layer 150 interposed between the first and second electrodes.

The first electrode 110 may be an anode and the second electrode 180 may be a cathode. As a result, the first electrode 110 may be formed of a conductive material having a higher work function than the second electrode 180. For example, the first electrode 110 may be made of indium tin oxide (ITO) or indium zinc oxide (IZO). The second electrode 180 may be made of aluminum (Al), calcium (Ca), magnesium (Mg), silver (Ag), or the like.

The organic light emitting layer 150 emits first light as excitons formed by recombination of the first and second charges provided from the first electrode 110 and the second electrode 120 fall into a ground state.

The organic light emitting layer 150 may be formed of a mixture of a host and a dopant. At this time, recombination of the first and second charges occurs in the host molecule so that the host first becomes an excited state, and the energy of the excited state is transferred to the dopant molecule. Thus, the dopant molecules generate light while falling into a stable ground state after being excited. That is, as the host transfers energy so that the dopant can emit light, the dopant having a higher luminous efficiency than the host emits light, thereby improving luminous efficiency.

The organic light emitting layer 150 may emit light in various colors such as blue, green, and blue depending on the material of the host and the dopant. For example, when the organic light emitting layer 150 emits blue light, the dopant may be 2,5,8,11-tetra-3-butylperylene. In addition, the host may be made of materials that do not violate the inherent color of the dopant. Thus, the host is 4,4'-bis (2,2-diphenyl-ethen-1-yl) -diphenyl (4,4'-bis (2,2-diphenyl-ethene-1-yl) -diphenyl DPVBi), spiro-DPVBi, and DPVBi derivatives.

In addition, when the organic light emitting layer 150 emits green light, the dopant may be quinacridone or coumarin. In addition, the host may be aluminum tris (8-hydroxyquinoline; Alq3).

In addition, when the organic light emitting layer 150 emits red light, the dopant is 2-methyl-6- (2- (2,3,6,7, tetrahydro-1H, 5H-benzoquinolizine-9-). (L) ethenyl) -4H-pyran-4-ylidene) propane-nitrile) (2-metyle-6- (20 (2,3,6,7-tetrahydro-1H, 5H-benzo quinolizin-9-yl ) ethenyl) -4H-pyran-4-ylidene) propane-dinitrile (DCM2) or rubrene. The host material is (N, N-bis (naphthalen-1-yl) phenyl-N, N'-bis (phenyl) benzidiine (N, N'-bis (naphthanlen-1-yl-phenyl) -N, N'-bis (phenyl) benzidine; NPB).

In this case, the first charge injection layer 120 and the first charge transport layer 130 are further interposed between the first electrode 110 and the organic light emitting layer 150. Here, the first charge injection layer 120 serves to easily release the first charge from the first electrode 110 to the first charge transport layer 130. In this case, in order for the first charge injection layer 120 to easily release holes to the first electrode 110, the first charge injection layer 120 is made of a material having a small work function difference from the first electrode 110. . In this case, an example of a material for forming the first charge injection layer 120 is 4,4 ', 4 "-tris (3-methylphenyl-N-phenylamino) triphenylamine) (4,4', 4" -tris ( 3-methylphenyl-N-phenylamino) triphenylamine; m-MTDATA) or copper phthalocyanine (CuPc).

In addition, the first charge transport layer 130 serves to transport the first charge provided from the first electrode 110 to the organic light emitting layer 150. Examples of the material for forming the first charge transport layer 130 are N, N-bis (naphthalen-1-yl) phenyl-N, N-bis (phenyl) benzidine (N, N'-bis (naphthalen-1-ul) or a benzidine derivative such as phenyl) -N, N'-bis (phenyl) benzidine; NPB).

As a result, the first charge may be smoothly provided to the organic light emitting layer 150 to improve the luminous efficiency.

However, there is a limit in improving the luminous efficiency of the organic light emitting diode device, and also there is a problem in that the color purity and life are reduced.

Such a problem was able to determine the cause through Experimental Example 1.

Experimental Example  One

2 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode device according to a first experimental example.

Referring to FIG. 2, an organic light emitting diode device basically includes an anode 210, a hole injection layer 220, a hole transport layer 230, an organic light emitting layer 240, an electron transport layer 250, and an electron on a substrate 200. The injection layer 260 and the cathode 270 were sequentially formed.

At this time, in order to form the organic light emitting layer 240, the host is first deposited on the hole transport layer 230 to a thickness of 250 Å. Thereafter, a dopant layer 240b is formed by doping a dopant in a portion of the host. Here, the doped layer 240b is formed to a thickness of 120 kPa. Therefore, the organic light emitting layer 240 is divided into a host layer 240b and a doped layer 240a.

3 is a cross-sectional view of an organic light emitting layer showing a formation position of a doped layer among various organic light emitting diode devices manufactured by the manufacturing method according to the first experimental example.

 As shown in FIG. 3, based on the interface 300 of the hole transport layer 230 and the organic light emitting layer 240. At this time, the thickness of the organic light emitting layer 240 was formed to 250 Å.

That is, the organic light emitting layer of the first organic light emitting diode device a is formed only of the doped layer 240a. In the second organic light emitting diode device (b), a doping layer 240a is formed from the interface 300 of the hole transport layer 230 and the organic light emitting layer 240, and a host layer 240b is formed on the doping layer 240a. Is formed. The third to fifth organic light emitting diode elements c, d, and e are formed of a doped layer 240a at intervals of 40 mW, 80 mW, and 120 mW from the interface 300 among the organic light emitting layers, respectively.

FIG. 4 is a diagram illustrating light emission efficiencies of organic light emitting diode devices in which a doped layer is changed in an organic light emitting layer.

As shown in FIG. 4, as the doping layer moves away from the interface between the hole transport layer and the organic light emitting layer, the light emission efficiency may be lowered. In addition, when comparing the light emission efficiency of the first organic light emitting diode device (a) and the second organic light emitting diode device (b), it was confirmed that about 70% of the total light emission at the interface between the hole transport layer and the organic light emitting layer.

This is because light is generated as the first and second charges are mainly recombined at the interface between the hole transport layer 230 and the organic light emitting layer 240. At this time, the excitation energy of the organic light emitting layer 240 is transferred to the hole transport layer 230 at the interface between the hole transport layer 230 and the organic light emitting layer 240 to emit light to the hole transport layer 230 may lower the luminous efficiency and color coordinates In addition, the hole transport layer 150 may be degraded to shorten the lifespan of the organic light emitting diode device.

Therefore, through Experimental Example 1, since the first charge and the second charge are mainly recombined at the interface between the hole transport layer 230 and the organic light emitting layer 240, it is confirmed that light emission efficiency, color coordinates, and lifetime are deteriorated. Could.

Thus, as shown in FIG. 1, the auxiliary emission layer 140 having a lower luminous efficiency than the organic light emitting layer 150 is interposed between the first charge transport layer 130 and the organic light emitting layer 150. As a result, light emission of the first charge transport layer 130 may be reduced by minimizing light emission at the interface between the first charge transport layer 130 and the auxiliary emission layer 140.

At this time, the auxiliary light emitting layer 140 should emit light of the same color as the organic light emitting layer 150 in order not to reduce the color purity. In addition, the auxiliary light emitting layer 140 should be selected as a material having excellent interface stability with the organic light emitting layer 150. The auxiliary light emitting layer 140 is preferably made of the host material forming the organic light emitting layer 150.

For example, when the organic light emitting layer 150 emits blue light, the material of the auxiliary light emitting layer 140 is 4,4'-bis (2,2-diphenyl-ethen-1-yl) -diphenyl (4). , 4'-bis (2,2-diphenyl-ethene-1-yl) -diphenyl; DPVBi), spiro-DPVBi, DPVBi derivatives and the like. In addition, when the organic light emitting layer 150 emits green light, the forming material of the auxiliary light emitting layer 140 may be aluminum tris (8-hydroxyquinoline; Alq3). When the light emitting layer 150 emits red light, the material of the auxiliary light emitting layer 140 is (N, N-bis (naphthalen-1-yl) phenyl-N, N'-bis (phenyl) benzidiyne (N, N'-bis (naphthanlen-1-yl-phenyl) -N, N'-bis (phenyl) benzidine; NPB).

The thickness of the auxiliary light emitting layer 140 may be 1/2 or less of the thickness of the organic light emitting layer 150. This is because, when the thickness of the auxiliary light emitting layer 140 is 1/2 or more of the thickness of the organic light emitting layer 150, the luminous efficiency is sharply lowered.

At this time, the thickness of the auxiliary light emitting layer 140 and the organic light emitting layer 150 is formed to 100 to 500Å. In this case, the stability of the device is lowered when it is formed below 100 kW, whereas the driving voltage becomes a problem when it is formed above 500 kW. Therefore, the thickness of the auxiliary light emitting layer 140 may be formed to 50 to 250Å.

In addition, the organic light emitting diode device may further include a second charge transport layer 160 and a second charge injection layer 170 interposed between the organic light emitting layer 150 and the second electrode 180. Here, the second charge injection layer 170 easily releases the second charge from the second electrode 180 and provides it to the second charge transport layer 160. An example of a material for forming the second charge injection layer 170 may be made of lithium fluoride (LiF). The second charge transport layer 160 serves to smoothly transport the second charge to the organic light emitting layer 150. Examples of the material for forming the second charge transport layer 160 include (2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (2- (4- biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole; PBD) or aluminum tris (8-hydroxyquinoline; Alq3) and the like.

Hereinafter, in Experimental Examples 2 to 4, an organic light emitting diode device having the same shape as that of FIG. 1 was manufactured to examine color coordinate characteristics of the organic light emitting diode device with respect to the thickness of the auxiliary light emitting layer.

Experimental Example  2

ITO was deposited on the substrate 100 to form the anode 110. Here, the anode 110 could be formed using a sputtering method. Thereafter, a hole injection layer 120 was formed on the anode 110. The hole injection layer 120 was formed by vacuum deposition of m-MTDATA. Thereafter, the hole transport layer 130 is formed on the hole injection layer 120. The hole transport layer 130 was formed by vacuum depositing NPB. Thereafter, the auxiliary light emitting layer 140 was formed on the hole transport layer 130. The auxiliary light emitting layer 140 is 4,4'-bis (2,2-diphenyl-ethen-1-yl) -diphenyl (4,4'-bis (2,2-diphenyl-ethene-1-yl)- diphenyl; DPVBi) was formed by vacuum deposition. Here, the auxiliary light emitting layer 140 was formed to a thickness of 40 kPa. Thereafter, the organic light emitting layer 150 was formed by co-depositing the blue host DPVBi and the blue dopant 2,5,8,11-tetra-3-butylperylene on the auxiliary light emitting layer 140. At this time, the doping amount of the dopant was 9% of the weight of the host. At this time, the organic light emitting layer 150 was formed to a thickness of 250 kPa. Thereafter, the electron transport layer 160 was formed on the organic light emitting layer 150. The electron transport layer 160 was formed by vacuum evaporation of Alq3. Thereafter, the electron injection layer 170 is formed on the electron transport layer 160. The electron injection layer 170 was formed by vacuum depositing LiF. Thereafter, the cathode 180 is formed on the electron injection layer 170. The cathode 180 was vacuum-deposited Al to complete the organic light emitting diode device.

Experimental Example  3

In the third experimental example, except for the thickness of the auxiliary light emitting layer, the organic light emitting diode device was completed through the same material and manufacturing method as the second experimental example.

At this time, the auxiliary light emitting layer 140 is formed to 80 Å.

Experimental Example  4

In the fourth experimental example, except for the thickness of the auxiliary light emitting layer, the organic light emitting diode device was completed through the same material and manufacturing method as the second experimental example.

In this case, the auxiliary light emitting layer 140 is formed to 120 Å.

Comparative Example

In the comparative example, except that the auxiliary light emitting layer was not formed, the organic light emitting diode device was completed through the same material and manufacturing method as in the second experimental example.

FIG. 5 is a view illustrating emission spectra of organic light emitting diode devices manufactured according to Examples 2 and 4 and Comparative Examples. FIG.

As shown in FIG. 5, as the thickness of the auxiliary emission layer 140 increases, the emission peak shifts to a shorter wavelength, thereby confirming that the color coordinates are improved.

Conventionally, light is generated at the interface between the hole transport layer and the organic light emitting layer to reduce the color coordinates. Can be improved. This is because the host has better color reproducibility than dopant.

Therefore, in the exemplary embodiment of the present invention, an auxiliary light emitting layer made of a host material is further provided between the first charge transport layer and the organic light emitting layer to move the main light emitting region to the interface between the auxiliary light emitting layer and the organic light emitting layer. As a result, not only the luminous efficiency and lifespan of the organic light emitting diode device can be improved, but also the color coordinates can be improved.

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

As described above, the organic light emitting diode device according to the present invention includes an auxiliary light emitting layer between the first charge transport layer and the organic light emitting layer, and moves the main light emitting region to the interface between the auxiliary light emitting layer and the organic light emitting layer, thereby providing a light emitting efficiency of the organic light emitting diode device. And not only improved life span but also color coordinates.

Claims (13)

A first electrode; A first charge injection layer disposed on the first electrode; A first charge transport layer disposed on the first charge injection layer; An auxiliary light emitting layer disposed on the first charge transport layer; An organic light emitting layer disposed on the auxiliary light emitting layer and having a higher luminous efficiency than the auxiliary light emitting layer; And A second electrode disposed on the organic light emitting layer, The auxiliary light emitting layer is an organic light emitting diode device, characterized in that made of a host material constituting the organic light emitting layer. The method of claim 1, The organic light emitting layer is an organic light emitting diode device, characterized in that consisting of a mixture of a dopant and a host. The method of claim 1, The auxiliary light emitting layer is an organic light emitting diode device, characterized in that made of a light emitting material that emits the same color as the organic light emitting layer. delete The method of claim 1, The auxiliary light emitting layer is 4,4'-bis (2,2-diphenyl-ethen-1-yl) -diphenyl (4,4'-bis (2,2-diphenyl-ethene-1-yl) -diphenyl; DPVBi), Spiro-DPVBi, DPVBi Derivatives, Aluminum tris (8-hydroxyquinoline; Alq3) and (N, N-bis (naphthalen-1-yl) phenyl-N, N ' An organic light emitting diode, comprising: any one selected from -bis (phenyl) benzidiine (N, N'-bis (naphthanlen-1-yl-phenyl) -N, N'-bis (phenyl) benzidine; NPB) device. The method of claim 1, The thickness of the auxiliary light emitting layer is an organic light emitting diode device, characterized in that formed in less than 1/2 of the thickness of the organic light emitting layer. The method according to claim 6, The thickness of the auxiliary light emitting layer is an organic light emitting diode device, characterized in that 50 to 250Å. The method of claim 1, The organic light emitting diode device of claim 2, further comprising at least one of a second charge transport layer and a second charge injection layer interposed between the second electrode and the organic light emitting layer. Forming a first electrode on the substrate; Forming a first charge injection layer on the first electrode; Forming a first charge transport layer on the first charge injection layer; Forming an auxiliary light emitting layer on the first charge transport layer; Forming an organic light emitting layer having a higher luminous efficiency than the auxiliary light emitting layer on the auxiliary light emitting layer; And Forming a second electrode on the organic light emitting layer, The auxiliary light emitting layer is a method of manufacturing an organic light emitting diode device, characterized in that formed with a host material for forming the organic light emitting layer. 10. The method of claim 9, The organic light emitting layer is a method of manufacturing an organic light emitting diode device, characterized in that formed by co-depositing the dopant and the host. 10. The method of claim 9, The auxiliary light emitting layer is a method of manufacturing an organic light emitting diode device, characterized in that made of a light emitting material that emits the same color as the organic light emitting layer. delete 10. The method of claim 9, Forming a second charge transport layer on the organic light emitting layer between the forming of the organic light emitting layer and the forming of the second electrode; And And forming a second charge injection layer on the second charge transport layer.

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