KR101950840B1 - Organic Light Emitting Device and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to an organic light emitting device that improves the efficiency and lifetime of a device by performing surface treatment before and after a light emitting layer or before and after a charge generating layer, and a method of manufacturing the same. In the method of manufacturing an organic light emitting device of the present invention, And a second electrode; and an organic light emitting device including a plurality of organic layers between the first electrode and the second electrode, wherein the plurality of organic layers include at least a hole transport layer, a light emitting layer, and an electron transport layer , And the surface treatment process is performed on at least one of the interfaces between the adjacent organic films.

Description

[0001] The present invention relates to an organic light emitting device,

The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device having improved efficiency and lifetime of a device by performing surface treatment before and after a light emitting layer or before and after a charge generating layer, and a method of manufacturing the same.

Recently, the field of display that visually expresses electrical information signals has rapidly developed as the information age has come to a full-fledged information age. In response to this, various flat panel display devices (flat display devices) having excellent performance such as thinning, light- Display Device) has been developed to replace CRT (Cathode Ray Tube).

Particularly, as the size of a display device is increased, a demand for a flat display device having less space occupation is increasing. As a specific example of such a flat panel display device, a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display (FED) device, and an organic light emitting diode (OLED) device.

Among these, an organic light emitting display device is considered as a competitive application for not requiring a separate light source, compacting the device, and displaying clear color images.

In such an organic light emitting display, it is essential to form a thin film transistor for driving and an organic light emitting element connected thereto. The organic light emitting element basically includes an anode and a cathode opposed to each other and a light emitting layer for emitting light between the anode and the cathode. .

The organic light emitting device is a device that injects electric charge into an organic layer formed on an anode and a cathode to form a pair of electrons and holes, and then extinguishes and emits light. This can be formed not only on a substrate that can be bent like a plastic but also because it can be driven at a lower voltage (10 V) than a plasma display panel or an inorganic electroluminescent device, have. In addition, organic light emitting devices can display three colors of green, blue, and red, and are display devices that express next-generation rich colors, and have become a target of many people.

2. Description of the Related Art Generally, an organic light emitting device is a device that emits light by stacking an organic layer between an anode made of ITO or the like and a cathode made of Al or the like by function and applying an electric field.

In general organic light emitting devices fabricated in this manner, the lifetime and efficiency of the device are greatly changed depending on the materials used, the lamination structure, and the surface treatment conditions of the anode.

Although many studies have been made to increase the lifetime and efficiency of organic light emitting devices, satisfactory results have not been found.

Such conventional organic light emitting devices have the following problems.

In the conventional organic light emitting device, after the surface treatment is performed on the anode, no separate surface treatment is performed on each organic layer included between the anode and the cathode.

In such conventional organic light emitting devices, there is a problem that the efficiency and lifetime are lowered due to the deterioration of the interface characteristics between the hole transporting layer and the light emitting layer among the organic material layers included between the anode and the cathode.

It is an object of the present invention to provide an organic light emitting device having improved efficiency and lifetime of a device by performing surface treatment before and after a light emitting layer or before and after a charge generating layer and a method of manufacturing the same. .

According to another aspect of the present invention, there is provided a method of fabricating an organic light emitting diode including a first electrode and a second electrode facing each other, and a plurality of organic layers between the first electrode and the second electrode, The present invention is characterized in that at least one of the interfaces between adjacent organic layers in the organic light emitting device including the hole transport layer, the light emitting layer, and the electron transport layer formed at least in turn in the organic film of the layer is characterized in that the surface treatment process is performed.

In this case, the surface treatment process may be performed after forming the hole transport layer.

When the hole transport layer has a plurality of layers, the surface treatment process can be performed on at least one of the interfaces between the plurality of the hole transport layers.

Alternatively, the surface treatment process may be performed after the light emitting layer is formed.

When the electron transporting layer has a plurality of layers, the surface treatment may be performed on at least one of the interfaces between the electron transporting layers.

When a plurality of units of a stacked body of a hole transporting layer, a light emitting layer and an electron transporting layer formed in sequence are formed between the first electrode and the second electrode, an n-type charge generation layer and a p-type charge generation layer are stacked Can be formed. In this case, the surface treatment process can be performed just before or immediately after the formation of the p-type charge generation layer.

On the other hand, the surface treatment step can be conducted by heat treatment at a temperature not lower than the glass transition temperature of the object to be surface-treated and not higher than the thermal decomposition temperature. Or may be heat treated at a temperature lower than the glass transition temperature of the object to be surface-treated, or may be irradiated with ultraviolet rays (UV) on the upper surface of the object to be surface-treated.

Alternatively, the surface treatment step may be performed by irradiating infrared rays to an upper surface of the object to be surface-treated, or by plasma-treating an object to be surface-treated.

The surface treatment step may include a surface treatment part in a chamber for forming an organic film to be surface-treated.

Alternatively, the surface treatment step may include a surface treatment part between the first chamber forming the hole transporting layer, the second chamber forming the light-emitting transporting layer, and the third chamber forming the electron transporting layer. In this case, the surface treatment unit may be provided between the first chamber and the second chamber, or between the second chamber and the third chamber, on a line passing through the substrate including the organic light emitting device.

Alternatively, the surface treatment process may be performed in a separate surface treatment chamber other than the chamber for forming the organic layers included in the organic light emitting device.

It is preferable that the thickness of the hole transporting layer is 30% to 50% of the total thickness of the organic film between the first electrode and the second electrode.

Also, the surface treatment step may include a heat treatment chamber between the n-type charge generation layer and the p-type charge generation layer, or may include a heat treatment chamber after the p-type charge generation layer.

In this case, a heat ray, a heat plate, or a beam is provided in the heat treatment chamber, and the first stack and the substrate including the n-type charge generation layer on the first stack are passed through the surface heat treatment.

According to another aspect of the present invention, there is provided an organic light emitting diode comprising a first electrode and a second electrode which are opposed to each other, and a plurality of organic layers between the first electrode and the second electrode, The film includes a hole transporting layer, a light emitting layer and an electron transporting layer which are sequentially formed, and at least one of the interfaces between the adjacent organic films has a surface treatment.

Further, a hole injection layer may be formed between the first electrode and the hole transport layer, and an electron injection layer may be further formed between the second electrode and the electron transport layer.

The organic light emitting device of the present invention and the method of manufacturing the same have the following effects.

It is possible to increase the efficiency of hole transport or electron transport by increasing the adhesion of the interface characteristics by advancing the surface treatment on the interface between the organic films having weak interface characteristics among the plurality of organic films formed between the first and second electrodes. In addition, the effect of lowering the driving voltage and the lifetime can be improved.

Particularly, in the case of the interface between the hole transport layer having the largest energy level difference and the light emitting layer, or in the case of the tandem-type structure, in the case of the surface of the charge generation layer or in the case of the charge generation layer of two or more layers, surface treatment can be performed between layers to stabilize the interface characteristics .

1 is a cross-sectional view illustrating an organic light emitting device according to a first embodiment of the present invention;
FIGS. 2A and 2B are diagrams showing the state of the organic light emitting device of FIG. 1 when the surface treatment is not carried out before the formation of the light emitting layer,
Fig. 3 is a process diagram showing a surface treatment method of the first type proceeding to the organic luminescent element of the present invention
4 is a process diagram showing a surface treatment method of a second method which proceeds to the organic light emitting device of the present invention
5 is a process diagram showing a surface treatment method of the third scheme proceeding to the organic light emitting device of the present invention
FIGS. 6A and 6B show the results of the case where the heat treatment was not performed on the surface of the hole transporting layer after the deposition of the hole transporting layer,
7 is a graph showing the current efficiency versus driving voltage when the organic light emitting device of the present invention is subjected to the surface treatment after the deposition of the hole transporting layer,
8 is a graph showing changes in the lifetime of the organic light emitting device according to the present invention when the hole transport layer is deposited,
9 is a cross-sectional view illustrating an organic light emitting device according to a second embodiment of the present invention
Fig. 10 is a view showing the surface after the n-type charge generation layer and the p-type charge generation layer junction interface of Fig. 9
11A and 11B are views showing a heat treatment method according to a second embodiment of the present invention and a heat treatment apparatus used therefor
12 is a graph showing the lifetime after the formation of the n-type charge generation layer and after the heat treatment in the structure of the second embodiment of the present invention
13 is a graph showing the IV characteristics at T95 after the formation of the n-type charge generation layer and the heat treatment in the structure of the second embodiment of the present invention

Hereinafter, an organic light emitting device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

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

1, an organic light emitting device according to a first embodiment of the present invention includes a substrate 1, first and second electrodes 2 and 8 opposed to each other, a first electrode 2, A hole transporting layer 4, a light emitting layer 5, an electron transporting layer 6 and an electron injecting layer 7 formed between the first electrode 8 and the second electrode 8 in this order.

When a voltage is applied to the first electrode 2 and the second electrode 8, holes are injected from the second electrode 8 into the organic light emitting device, In the light emitting layer 5, holes and electrons are recombined to generate excitons, and the excitons fall to the ground state and light is emitted. Here, either the first electrode 2 or the second electrode 8 is formed on the substrate, and the substrate includes a thin film transistor for driving. The thin film transistor is connected to the first electrode 2 or the second electrode 8 formed on the substrate, and an electrical signal is connected thereto. Here, the electrode connected to the thin film transistor may be patterned pixel by pixel.

The hole injection layer 3 receives holes from the first electrode 2 and transports the holes to the hole transport layer 4. The hole transport layer 4 injects holes from the hole injection layer 3 into the light emitting layer 5 ). Similarly, the electron injecting layer 7 receives electrons from the second electrode 8 and transports them to the electron transporting layer 6. The electron transporting layer 6 receives electrons from the electron injecting layer 7, (5).

The hole injection layer 3 and / or the electron injection layer 7 may be omitted in some cases. Alternatively, the hole injecting layer 3 may be formed as one layer by co-evaporating the materials forming each layer together with the hole transporting layer 4, and the electron injecting layer 7 may be formed as a separate layer, Or may be formed by injecting a thin metal dopant into the surface of the substrate 6.

Here, the electron injection layer 7 from the hole injection layer 3 between the first and second electrodes 2 and 8 is made of an organic film of an organic material, and a small amount of inorganic material . ≪ / RTI >

In the case of the conventional organic light emitting device, after the surface treatment of the surface of the first electrode 2, the organic layers proceeded without surface treatment, but the organic light emitting device of the present invention was subjected to surface treatment at the interface between the organic layers And the characteristic at the interface is stabilized.

In the method of manufacturing an organic light emitting diode of the present invention, in consideration of the difference in adhesion characteristics at the interface due to the phase difference of the material constituting each organic layer, it is preferable that hole transport and electron transport be performed more smoothly The surface treatment process is carried out before or after the light emitting layer.

Hereinafter, interfacial characteristics in the case where the surface treatment step is carried out and in the case where the surface treatment step is not carried out will be described with reference to the drawings.

FIGS. 2A and 2B are diagrams showing the state of the organic light emitting device of FIG. 1 when the surface treatment is not carried out before the formation of the light emitting layer and when the organic light emitting device is advanced. FIG.

2A, when the light emitting layer 5 is immediately formed on the hole transporting layer 4, the light emitting layer 5 is formed on the rough surface of the hole transporting layer 4 unstably. In this case, the interface between the hole transporting layer 4 and the light emitting layer 5 is inferior in adhesiveness, which may cause a problem that the hole transporting property is deteriorated.

Since the difference in energy level between the hole transporting layer and the light emitting layer is largest among them, the interface between the hole transporting layer 4 and the light emitting layer 5 greatly affects the lifetime of the device. .

Accordingly, in the organic light emitting device according to the first embodiment of the present invention for improving such interfacial characteristics, after the hole transport layer 4 is deposited as shown in FIG. 2B, the surface thereof is subjected to surface treatment, Emitting layer 5 is formed.

In this case, the interface between the hole transporting layer 4 and the light emitting layer 5 has a more gentle surface characteristic, and the interlayer adhesion is improved.

Here, the thickness of the hole transport layer 4 may be 30% to 50% of the total thickness of the organic film between the first electrode and the second electrode. Alternatively, the thickness of the hole transport layer 4 may be about 1000 Å or more.

When the hole transport layer has a plurality of layers, the surface treatment process can be performed on at least one of the interfaces between the plurality of the hole transport layers. That is, the surface treatment may be applied to all the interfaces of the plural hole transporting layers, or alternatively, only the specific interface may be selected and applied. In this way, when the interfacial treatment is used for a plurality of the hole transporting layers, it is advantageous from the viewpoint of efficiency of the process that the surface treatment step is provided in the chamber for forming the hole transporting layer.

On the other hand, this surface treatment step is not performed only on the surface of the hole transporting layer 4 but can be performed immediately after the light emitting layer 5 is formed or at an interface between different organic layers. In addition, whether or not the surface treatment is performed and the surface treatment time / treatment degree can be selected in consideration of the initial interface characteristics between the respective layers and the constituent components of each layer.

When the electron transporting layer is provided with a plurality of layers, the surface treatment process can be performed on at least one of the interfaces between the electron transporting layers.

Specifically, the surface treatment process is performed in the following manner.

3 is a process diagram showing a surface treatment method of a first method to proceed to the organic light emitting device of the present invention.

3, the first surface treatment method includes a first chamber 310 for forming a hole injection layer and a second chamber 310 for forming a hole transport layer, which are arranged in a line and each have an organic material supply source 410 The substrate between the third chamber 330 for forming the light emitting layer and the fourth chamber 340 for forming the electron transport layer may be provided with the surface treatment sections 351 and 352 on the movement line line .

In the illustrated example, the surface treatment units 351 and 352 are disposed between the second chamber 320 and the third chamber 330 and between the third chamber 330 and the fourth chamber 340. And a surface treatment section may be further provided between the chambers corresponding to the corresponding interface where further surface treatment is required.

In this case, the surface treatment units 351 and 352 may be provided in the form of a linear source on a line passing through the substrate including the organic light emitting device, and may be formed of a material such as thermal, plasma plasma, ultraviolet (UV) or infrared rays can be supplied onto the substrate.

If the surface treatment units 351 and 352 are provided as linear sources corresponding to the moving direction of the substrate on the line on which the substrate moves, the substrate moves and the surface treatment is performed. Thus, Processing becomes possible.

Although various methods applicable to the process can be applied to the surface treatment method, a method capable of stabilizing the interface characteristics between the organic films is selected and proceeded.

For example, the surface treatment process can be performed by heat treatment at a temperature not lower than the glass transition temperature of the object to be surface-treated, and below the thermal decomposition temperature.

Or may be heat treated at a temperature lower than the glass transition temperature of the object to be surface-treated, or may be irradiated with ultraviolet rays (UV) on the upper surface of the object to be surface-treated.

Alternatively, the surface treatment step may be performed by irradiating infrared rays to an upper surface of the object to be surface-treated, or by plasma-treating an object to be surface-treated.

Here, the surface treatment units 351 and 352 are provided on the line on which the substrate moves, and may not be vacuum conditions.

Further, for example, in the case where the moving line is not a vacuum condition, the progress of the plasma surface treatment is made by providing the surface treatment section in a chamber for forming a layer requiring surface treatment, You may. Surface treatment such as heat, ultraviolet rays or infrared rays other than the plasma surface treatment may be performed by providing the surface treatment part in the chamber.

Although the illustrated example shows a case in which a chamber is provided on a line, in some cases, the surface treatment portion can be applied even in a structure in which the chamber is formed in a cluster shape.

4 is a process diagram showing a surface treatment method of a second method which proceeds to the organic light emitting device of the present invention.

4, the surface treatment method according to the second method of the present invention has a standby portion 560 and a robot arm (not shown) in which a substrate containing an organic light emitting element is introduced / waiting in the center, A first chamber 510 for forming a hole injection layer, a second chamber 520 for forming a hole transport layer, a third chamber 530 for forming a light emitting layer, a fourth chamber 540 for forming an electron transport layer, and a separate independent surface May be accomplished by clustered equipment (500) having a processing chamber (550).

In this case, after a layer to be surface-treated is formed in a step requiring surface treatment, the substrate is drawn into the surface treatment chamber 550 using the robot arm in a state in which the substrate is standing by at the standby portion Then, the surface treatment proceeds. Subsequently, the substrate is moved to the atmosphere again, and then moved to the chamber for the next layer formation.

Here, when the surface treatment chamber 550 is separately provided, the surface treatment may be performed plural times as required.

5 is a process diagram showing a surface treatment method of a third type that proceeds to the organic light emitting device of the present invention.

5, the third type of surface treatment method of the present invention is characterized in that among the chambers 610, 620, 630, 640 disposed around the standby portion 650 in the cluster type equipment, Processing units 621 and 631, as shown in FIG. The explanation of this is the same as that in the case of arranging the chambers on the line, and therefore description thereof will be omitted.

FIGS. 6A and 6B are SEMs when the surface of the hole transport layer after the deposition of the hole transport layer does not undergo heat treatment and when the heat treatment is not performed.

In this experiment, the first electrode is formed on a substrate, and the pixel region is divided into a bank on the substrate. A state in which the hole transport layer and the light emitting layer are deposited in this order on the entire surface of the substrate including the banks is shown.

6A in which the heat treatment is not performed on the surface after the deposition of the hole transporting layer and the case of FIG. 6B in which the surface is heat-treated is compared with the case of the surface treatment after the deposition of the hole transporting layer. It can be seen that the hole transport layer has a gentle surface characteristic and then the interface between the hole transport layer and the light emitting layer is smoothly interfaced. That is, it can be confirmed that there is a change in interface between the hole transport layer and the light emitting layer before and after the surface treatment, and it can be predicted that the adhesion between the hole transport layer and the light emitting layer is improved by the smooth interface property.

In the following experiment, the case where the heat treatment is performed after the deposition of the hole transporting layer during the formation of the organic light emitting device in the structure of FIG. 1 is referred to as the present invention, and the case where the heat treatment is not carried out as the comparative example, We looked at the lifetime by the luminance change.

Here, the first electrode 2 was formed to have a thickness of 500 angstroms, the hole injection layer 3 formed to have a thickness of 300 angstroms, and the hole transport layer 4 to have a thickness of 750 angstroms. The light emitting layer 5 was formed by depositing BAlq doped with Ir (ppy) 3 in an amount of 10% to a thickness of 250 ANGSTROM. The electron transport layer 6 was made of LG201 to a thickness of 300 ANGSTROM, And the second electrode 8 was formed by depositing Al to a thickness of 1000 to form an organic light emitting device.

7 is a graph showing the current efficiency versus driving voltage for the case of surface treatment after deposition of the hole transporting layer of the organic light emitting device of the present invention and the case thereof.

As shown in FIG. 7, in the case of the present invention, it was confirmed that the current efficiency was higher with respect to the driving voltage than the comparative example. In the case of the driving voltage of 4V, It can be seen that the current efficiency is about twice as high at the same driving voltage.

This means that the present invention can be implemented with a smaller driving voltage than the comparative example when the desired current efficiency is desired.

8 is a graph showing changes in the lifetime of the organic light emitting device according to the present invention when the hole transport layer is deposited and after the surface treatment.

As shown in FIG. 8, when the lifetime of the device is defined as a point at which the luminance is reduced by 50% from the initial state, the comparative example is 175 hours, whereas the present invention is observed at about 350 hours, there was.

This is a result of the case where the surface heat treatment of the hole transport layer is applied once, and it can be predicted that the heat treatment or the other surface treatment at the interface between the organic film has a higher efficiency and an improved lifetime.

In the meantime, the structure of FIG. 1 and the experiment described above are based on the assumption that a single unit of the hole transporting layer, the light emitting layer, and the electron transporting layer is formed between the first and second electrodes, The organic light emitting device has been described.

The effect of the surface treatment process described above can be expected in a tandem-type structure or a hybrid-type organic light-emitting device in addition to the mono device.

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

As shown in FIG. 9, the second embodiment of the present invention relates to a tandem organic light emitting diode, which includes a first electrode 100 and a second electrode 200 facing each other, A first and a second stack formed between the electrodes 200 and a charge generation layer 140 having a stacked structure of an n-type layer 141 and a p-type layer 142 located between the adjacent stacks.

The first electrode 100 and the second electrode 200 may be an anode and a cathode or may be reversed so that the first electrode 100 is a cathode and the second electrode 200 is a cathode. A substrate (not shown) having a thin film transistor array is disposed under the first electrode 100, and the thin film transistor formed on one pixel of the thin film transistor array is connected to the first electrode 100.

In a tandem-type organic light emitting device, a stack is at least two, and the number of stacks can be increased by interposing a charge generating layer between the stacks.

Each of the stacks includes a light emitting layer 120 and a light emitting layer 170 which emit light of a predetermined color at the center, a first common layer 1100 and 1500 below the light emitting layers 120 and 170, 2 common layers 130 and 1800. In FIG.

The first common layer 1100 and 1500 may include a hole injection layer 105 or 150 and / or a hole transport layer 110 or 160. The second common layer 130 may include an electron transport layer 180 ) And / or an electron injection layer (190). The hole injection layer and the hole transport layer may be formed as one layer, or each layer may be divided into a plurality of layers. Similarly, the electron transporting layer and the electron injecting layer may be formed as one layer, or each layer may be divided into a plurality of layers.

In the illustrated example, the first common layer 1100, 1500 is formed in common in the first and second stacks, and the second common layer is formed by the second common layer 130 of the first stack Shows a state where only a single electron transporting layer and a second common layer of the second stack are formed with an electron transporting layer and an electron injecting layer.

On the other hand, in the figure, the surface of the first common layer of each stack, the surface of the light-emitting layer, the surface of the n-type charge generation layer 141 and the surface of the p-type charge generation layer 142 Treatment was carried out.

The surface treatment process is added to the charge generation layer 140 as compared with the first embodiment. In the surface treatment in this case, the charge generation layer has an organic structure as a basic structure, helps transfer of holes / electrons into the charge generation layer, And includes a dopant for adjusting the balance, which functions to prevent the dopant from flowing into the other layer and acting as an impurity.

As described above, the surface treatment may be at least one on the interface between the above-described adjacent organic films, and may be performed on all of the interfaces as shown in FIG. 9, and only one or a part of the surface treatment may be selectively performed.

10 is a view showing the surface after the n-type charge generation layer and the p-type charge generation layer junction interface of FIG. 9 are subjected to surface treatment.

10, after the n-type charge generation layer 141 is formed and after the surface treatment such as heat treatment is performed, the interface characteristics with the p-type charge generation layer 142 formed later can be improved, It is possible to expect a rise and a drop in driving voltage, thereby achieving an improvement in the lifetime by stabilizing the interface characteristics.

Hereinafter, the case where the interface treatment is carried out before formation of the p-type charge generation layer after the formation of the n-type charge generation layer in the charge generation layer will be described.

When a tandem structure is substantially used, the n-type charge generation layer formed after the first stack is doped with an alkali metal series such as Li or a metal such as Ca, Mg or Cs. Such a doping metal, when driven after the formation of the stack of the first stack, the n-type charge generation layer, the p-type charge generation layer and the second stack, does not stay in the n-type charge generation layer, For example, there is a problem of spreading to the hole transport layer, which causes a problem that the long life of the tandem device is reduced.

The heat treatment method and experiment described below solves this problem of an actual tandem device and shows that the lifetime is improved through the experiment.

11A and 11B are views showing a heat treatment method and a heat treatment apparatus used therefor according to a second embodiment of the present invention.

Although a total of four chambers of the first to fourth chambers 610, 620, 630 and 640 are shown in FIG. 11A, the first chambers 610 constitute one chamber forming the first stack , The number can be increased according to the organic material source used to form the layer.

The substrate 710 in which the first stack is formed in the first chamber 610 moves to the second chamber 620, and an n-type charge generation layer is formed. After the formation of the n-type charge generation layer, the n-type charge generation layer is moved to the third chamber 630 for heat treatment and the surface treatment is performed on the n-type charge generation layer. In this case, as shown in FIG. 11B, a heat ray 805 or a heat plate or a beam is disposed below the substrate 710 to control the temperature used in the surface treatment. Is treated within a temperature range of approximately 100 DEG C to 150 DEG C, and the time is applicable for as short as 1 minute to as long as 1 hour. Here, the n-type charge generation layer may directly face the heat ray 805 or the heat plate or the beam, or such means may correspond to the back side of the substrate and indirectly transmit to the surface of the n-type charge generation layer by heat It might be.

Further, after the heat treatment, the p-type charge generation layer is formed on the surface-treated n-type charge generation layer by moving to the fourth chamber 640 for the p-type charge generation layer immediately inline.

12 is a graph showing the lifetime of the n-type charge generation layer after the formation of the n-type charge generation layer in the structure of the second embodiment of the present invention.

Condition Life @ T95 The driving voltage (V) The luminance (Cd / A) CIEx CIEy Quantum efficiency (EQE) Comparative Example 3600hr 7.5 77.7 0.313 0.318 32.2 110 ° C, 20 min 3600hr 7.5 75.4 0.321 0.326 30.6 110 ° C, 30 min 5000hr 7.6 77.5 0.319 0.321 32.0 110 DEG C, 40 min 4320hr 7.8 77.2 0.319 0.321 31.8 140 DEG C, 1.3 min 3830hr 7.5 77.4 0.314 0.317 32.1 140 ° C, 2 min 3955hr 7.6 76.5 0.313 0.310 32.3 150 ° C, 1 min 4580hr 7.4 78.8 0.315 0.322 32.2

As can be seen from the data in Table 1 and FIG. 12, when the heat treatment temperature is about 110 ° C., it is found that the driving voltage is hardly increased and the lifetime is improved by maintaining the time of about 30 minutes. Here, the increased lifetime is about 38% or more of the comparative example, and the reliability of the tandem element can be expected to be improved.

In addition, when heat treatment is performed at a higher temperature of 150 占 폚, the driving voltage is lowered by 0.1 V due to the heat treatment for about 1 minute, and the lifetime is 4580 hr, which shows a synergistic effect of more than 27% Able to know. Here, it is confirmed that the quantum efficiency has an equal effect and the luminance is further increased.

On the other hand, in the above experiment, the comparative example means that the heat treatment is not performed after the formation of the n-type charge generation layer.

And, in the above experiment, the T95 lifetime means the elapsed time until the initial state efficiency drops to about 95% efficiency, assuming 100% efficiency.

By virtue of such a heat treatment process, an effect of improving lifetime by about 20% or more can be obtained as compared with a structure without heat treatment.

On the other hand, in FIG. 12, the vertical axis indicates that the efficiency drops to a level of 95% when the efficiency of the initial state is taken as 100%, and the horizontal axis represents the life of 100%.

As shown in FIG. 12, the line graphs of the heat treatments (2) and (3) show relatively improved lifespan than the comparative example (1), and the effect of improving the service life It means increasing.

 13 is a graph showing I-V characteristics at T95 after the heat treatment after the formation of the n-type charge generation layer in the structure of the second embodiment of the present invention.

13, in the tandem structure of the second embodiment of the present invention, if the heat treatment is not performed after formation of the n-type charge generation layer, the current density is high in the initial state as shown by the line graph (1) As shown in the graph, it can be seen that the current density remarkably drops with respect to the same drive voltage at the point of 95% efficiency.

In the case of the present invention, as shown in the line graph (2), the IV characteristic in the case of 95% efficiency compared with the initial state is almost similar to that in the comparative example before the lifetime (T100) It can be seen that the IV characteristic is improved at the same time as the after-life improvement.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

1: substrate 2: first electrode
3: Hole injection layer 4: Hole transport layer
5: luminescent layer 6: electron transport layer
7: electron injection layer 8: second electrode

Claims (26)

delete delete delete delete delete Providing a first electrode on a substrate;
Forming a first stack on the first electrode, the first stack including a first hole transporting layer, a first light emitting layer, and a first electron transporting layer;
Forming an n-type charge generation layer comprising a first organic material host and a first charge balance dopant on the first electron transporting layer;
Immediately after forming the n-type charge generation layer, surface-treating the n-type charge generation layer to prevent diffusion of the first charge balance dopant outside the n-type charge generation layer;
Forming a p-type charge generation layer comprising a second organic material host and a second charge balance dopant on the n-type charge generation layer;
Forming a second stack on the p-type charge generating layer, the second stack including a second hole transporting layer, a second light emitting layer and a second electron transporting layer; And
And forming a second electrode on the second stack. ≪ Desc / Clms Page number 20 > The method according to claim 6,
Forming a p-type charge generation layer on the surface of the p-type charge generation layer to prevent diffusion of the second charge balance dopant outside the p-type charge generation layer. Way. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer proceeds by heat treatment at a temperature not lower than a glass transition temperature of the n-type charge generation layer and not higher than a thermal decomposition temperature. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer progresses by heat treatment at a temperature not higher than the glass transition temperature of the n-type charge generation layer. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer is performed by irradiating ultraviolet rays (UV) onto the n-type charge generation layer. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer is performed by irradiating infrared rays onto the n-type charge generation layer. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer is performed by plasma treatment of the n-type charge generation layer. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer comprises a surface treatment part in a chamber for forming the n-type charge generation layer. The method according to claim 6,
The first hole transporting layer, the first light emitting layer and the second electron transporting layer in the first stack,
Further comprising the step of surface-treating the upper portion of the second stack immediately after formation of at least one of the second hole transport layer, the second light emitting layer and the second electron transport layer. 15. The method of claim 14,
Characterized in that the surface treatment step is provided on a line passing through the substrate between a first chamber forming a layer to be surface-treated and a second chamber forming a layer positioned after the surface treatment A method of manufacturing an organic light emitting device. The method according to claim 6,
Wherein the surface treatment of the n-type charge generation layer is performed in a separate surface treatment chamber in addition to the chamber in which the n-type charge generation layer is formed. 15. The method of claim 14,
Wherein the thickness of the first hole transporting layer is 30% to 50% of the total thickness of the organic film between the first electrode and the second electrode. 8. The method of claim 7,
The surface treatment of the n-type charge generation layer includes a first heat treatment chamber between a chamber forming the n-type charge generation layer and a chamber forming the p-type charge generation layer,
Wherein the surface treatment of the p-type charge generation layer comprises a second heat treatment chamber adjacent to the chamber for forming the p-type charge generation layer. 19. The method of claim 18,
In the first heat treatment chamber, a heat ray, a heat plate, or a beam is provided, and when the substrate including the n-type charge generation layer passes over the top,
Wherein the second heat treatment chamber is provided with a heat ray, a heat plate, or a beam, and is subjected to surface heat treatment when the substrate including the p-type charge generation layer passes over the topmost portion thereof. On a substrate, a first electrode;
A first stack including a first hole transporting layer, a first light emitting layer, and a first electron transporting layer sequentially disposed on the first electrode;
Wherein the first charge balancing dopant is uniformly distributed in the first organic material host and diffused to the outside is prevented from being diffused on the first electron transporting layer, the first charge transporting layer comprising a first organic material host and a first charge balance dopant, Type charge generation layer;
A p-type charge generation layer comprising a second organic material host and a second charge balance dopant, on the n-type charge generation layer;
A second stack including a second hole transporting layer, a second light emitting layer, and a second electron transporting layer sequentially on the p-type charge generating layer; And
And a second electrode on the second stack. 21. The method of claim 20,
At least one of the first hole transporting layer and the second hole transporting layer has a plurality of organic layers,
Wherein at least one of the interfaces of the plurality of organic layers is surface-treated. 21. The method of claim 20,
At least one of the first electron transporting layer and the second electron transporting layer has a plurality of organic layers,
Wherein at least one of the interfaces of the plurality of organic layers is surface-treated.
delete 21. The method of claim 20,
Wherein the p-type charge generation layer is surface-treated to uniformly distribute the second charge balance dopant in the second organic material host and prevent diffusion to the outside. 21. The method of claim 20,
Wherein the thickness of the first hole transporting layer is 30% to 50% of the total thickness of the organic film between the first electrode and the second electrode. 21. The method of claim 20,
Wherein an electron injection layer is further formed between the first electrode and the first hole transporting layer and between the second electrode and the second electron transporting layer.

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