KR20130021751A - Method for manufacturing organic emitting display device - Google Patents

Abstract

PURPOSE: A method for manufacturing an organic light emitting display device is provided to minimize a hole entry barrier on an interface between an anode and an organic layer by improving the film quality of an anode. CONSTITUTION: A substrate is prepared(S10). An anode is deposited on a substrate(S20). An anode surface is pre-processed with plasma after the anode is deposited(S30). The substrate is loaded in the chamber for forming a hole injection layer(S40). The substrate is on standby in the chamber for forming the hole injection layer(S50). A hole injection layer is formed on the anode(S60). [Reference numerals] (S10) Preparing a substrate; (S20) Depositing an anode; (S30) Pre-processing the anode with plasma; (S40) Loading in the chamber for forming a hole injection layer of the substrate; (S50) Standby in a predetermined time of the substrate; (S60) Forming a hole injection layer

Description

Method for manufacturing organic light emitting display device {Method for Manufacturing Organic Emitting Display device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode display, and more particularly, to a method of manufacturing an organic light emitting diode display by minimizing a hole entrance barrier at an interface between an anode and an organic material layer by changing a process after plasma treatment of an anode to improve anode film quality. .

Video display devices that implement a variety of information as screens are the core technologies of the information and telecommunications era, and are developing in a direction that is thinner, lighter, more portable, and high performance. In addition, the demand for a flexible display that can be bent in the pursuit of space and convenience, and the organic light emitting display device for controlling the amount of emission of the organic light emitting layer in the flat panel display device has been in the spotlight.

The organic light emitting diode display may include an organic light emitting diode formed by sequentially stacking an anode, an organic light emitting layer, and a cathode on a substrate, and a capping layer covering and capping the organic light emitting diode.

The operating principle of the organic light emitting device is as follows. In other words, an electroluminescence phenomenon is applied by applying an electric field between the cathode and the anode formed at both ends of the organic light emitting layer to inject and transfer electrons and holes in the organic light emitting layer to combine with each other. After pairing, light is emitted from the excited state to the ground state.

Such an organic light emitting device uses a host and a dopant in forming the organic light emitting layer.

In this case, after forming an anode on a substrate, the organic light emitting layer of an organic component is formed between the anode and the cathode, and then emits light by applying an electric field.

The driving principle is that a voltage is applied to the anode and the cathode, respectively, and holes are injected from the anode, and electrons are injected from the cathode. In this way, the generated excitons fall to the ground state and emit light. Using the light is the principle of organic electroluminescence. In this case, each organic material layer may be formed between each electrode and the light emitting layer to facilitate injection of holes and electrons.

However, the above-described conventional organic light emitting display device has the following problems.

In general, in an organic light emitting diode display, an organic light emitting diode includes an anode and a cathode of a metal component, and an organic material layer (including an organic light emitting layer) of an organic component. In this case, hole injection or electron injection into the organic light emitting layer is not easy due to different energy level characteristics between the anode or cathode of the metal component and the organic material layer and the difference in the vacuum level.

In order to improve this, a method of modifying the surface of the anode by plasma pretreatment after the formation of the anode is used, but it is difficult to completely normalize the surface of the anode by such plasma pretreatment, and excessive plasma pretreatment may cause damage to the anode film. There is a problem that can be.

In addition, as the device becomes larger, there is a problem that the plasma pretreatment may appear unevenly for each region, and thus it is difficult to ensure uniform uniformity at the contact interface between the organic material layer including the organic light emitting layer and the anode.

In addition, the interface nonuniformity between the anode and the organic material layer causes deterioration of device driving characteristics and largely adversely affects the lifetime.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and improves the anode film quality by changing the process after the plasma treatment of the anode, thereby minimizing the hole entrance barrier at the interface between the anode and the organic material layer. The purpose is to provide.

According to an aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, the method comprising: depositing an anode on a substrate; and performing plasma pretreatment on the surface of the anode after the deposition of the anode; Loading the hole injection layer forming chamber and waiting for at least one minute; and depositing a hole injection layer on the anode in the hole injection layer forming chamber; And forming an organic light emitting layer and a cathode on the hole injection layer.

After the substrate on which the anode is deposited is loaded into the hole injection layer forming chamber, the hole injection layer forming organic molecules remaining in the hole injection layer forming chamber adhere to the surface of the anode.

After the substrate on which the anode is deposited is loaded into the hole injection layer forming chamber, the chamber for forming the hole injection layer is preferably maintained in a high vacuum state.

In the forming of the hole injection layer on the anode in the hole injection layer forming chamber, the hole injection layer forming organic material is uniformly supplied to the substrate side in the hole injection layer forming chamber.

The manufacturing method of the organic light emitting display device as described above has the following effects.

After the formation of the metal (electrode), the surface of the organic material layer forming chamber to be formed on the surface for a predetermined time, some molecules constituting the organic material layer remaining in the chamber is doped to the surface very small amount to improve the adhesion between the metal and the organic material layer The hole injection barrier or the electron injection barrier can be minimized.

Accordingly, the lifespan of the organic light emitting diode display may be improved by several tens or more times by improving the efficiency of hole injection and electron injection into the organic light emitting layer to improve device characteristics and to secure interfacial uniformity between layers.

1 is a cross-sectional view illustrating an organic light emitting display device according to an example formed by a method of manufacturing an organic light emitting display device of the present invention.
2 is a flowchart illustrating a method of manufacturing an organic light emitting display device according to the present invention.
3A to 3C are cross-sectional views illustrating a method of manufacturing an organic light emitting display device according to the present invention.
4A and 4B are cross-sectional views illustrating a process method of the present invention compared with the manufacturing method of the organic light emitting display device.
5 is a view showing energy levels at a junction interface between an anode and an organic material layer manufactured using the method of manufacturing an organic light emitting display device of the present invention.
FIG. 6 is a graph illustrating embodiments in which a waiting time of a hole injection layer forming chamber is changed when a method of manufacturing an organic light emitting display device is used, and a lifespan change according to a comparative example compared thereto

Hereinafter, a method of manufacturing an organic light emitting display device 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 display device according to an example formed by a method of manufacturing an organic light emitting display device of the present invention.

As illustrated in FIG. 1, the organic light emitting diode display manufactured by the method of manufacturing the organic light emitting diode display of the present invention may include, for example, a substrate 10, an anode 11, a hole injection layer 12, and a hole transport layer 13. , An organic light emitting layer 14, an electron transport layer 15, an electron injection layer 16, and a cathode 17.

Here, the anode 11 is formed of a transparent electrode, such as transparent indium tin oxide (ITO), indium zinc oxide (IZO), etc., when the bottom emission type, as shown in the illustrated example, the cathode 17 is aluminum (Al), etc. It is formed of a reflective metal.

In addition, the hole injection layer 12, the hole transport layer 13, the organic light emitting layer 14, the electron transport layer 15, and the electron injection layer 16 are all organic components, and the anode 11 and the cathode 17 are formed of organic materials. It functions as a kind of organic semiconductor 50 which transfers holes or electrons therebetween. Among these, the hole transport layer 13 and the electron transport layer 15 adjacent to the organic light emitting layer 14 are directly transferred to the organic light emitting layer 14.

The hole injection layer 12 and the electron injection layer 16 are layers provided to lower the hole injection barrier from the anode 11 of the electrode component or the electron injection barrier from the cathode 17, respectively.

On the other hand, even in the case where the above-described hole injection layer 12 or the electron injection layer 16 is provided with a layer for lowering the barrier between the organic semiconductor 50 and the metal (electrode), the metal and the organic material basically have Hole injection or electron injection can be difficult due to differences in vacuum levels and differences in work functions.

In order to solve this problem, in the method of manufacturing the organic light emitting display device of the present invention, an anode made of ITO or the like forms a hole injection layer after plasma treatment of a surface after film deposition. In addition, after the surface plasma treatment of the anode, the hole injection layer forming chamber is loaded with a substrate on which the anode is deposited, and then left for a predetermined time to improve the surface film quality of the anode, followed by forming a hole injection layer.

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

2 is a flowchart illustrating a method of manufacturing an organic light emitting display device, and FIGS. 3A to 3C are cross-sectional views illustrating a method of manufacturing an organic light emitting display device of the present invention.

2 to 3C, the method of manufacturing the organic light emitting display device of the present invention is performed in the following order.

First, as shown in FIG. 2 and FIG. 3A, after preparing the substrate 10 (S10), the anode 11 is deposited on the substrate 10 through a deposition method such as sputtering (S20). The anode 11 may be made of indium tin oxide (ITO), indium zinc oxide (IZO), or the like of the transparent electrode component.

In this case, due to the roughness of the surface after the deposition of the anode 11, it is not suitable to form a hole injection layer or other organic layer of the organic component directly on the anode (11). Immediately after deposition, the surface of the anode 11 has a large number of non-uniform irregularities on the surface. 3A illustrates a state in which an anode 11 is formed on the substrate 10 and then inverted.

Subsequently, in order to compensate for non-uniform film quality of the surface of the anode 11, plasma pretreatment is performed on the surface of the anode 11 (S30). Such plasma pretreatment may be in a separate chemical vapor deposition chamber (CVD chamber).

Subsequently, the substrate 10 on which the anode 11 is formed is loaded into the hole injection layer forming chamber (S40). For example, the hole injection layer forming chamber is an organic material deposition source is located in the lower side, in this case, the anode 11 is positioned with the surface facing downward during loading.

Subsequently, the substrate 10 is waited for a predetermined time in the hole injection layer forming chamber (S50). In this process, as shown in FIG. 3B, a small amount of organic molecules 12a of the hole injection layer component remaining in the hole injection layer forming chamber adhere to non-uniform irregularities on the surface of the anode 11, and the anode ( 11) to improve the surface film quality. At this time, the organic material for forming the hole injection layer is not intentionally supplied in the atmospheric process, but components remaining in the chamber naturally adhere to the surface of the anode by the atmosphere for a predetermined time. As a result, a very small amount of doping of the organic molecules 12a as the material for forming the hole injection layer is performed on the surface of the anode 11.

In this case, it is preferable to make the said waiting time into about 40 minutes or more in the laminated structure like FIG. However, the present invention is not necessarily limited to such a waiting time, and may be further added or decreased in consideration of the size or stack structure of the organic light emitting display device to be formed. For example, if the small device stack structure is small and the material is not bad even when the interface characteristics between the anode and the hole injection layer are not in the hole injection layer chamber, a small waiting time may be required.

In either case, however, the surface film quality of the anode may be improved by leaving more than the normal waiting time when loading into the hole injection layer forming chamber after plasma pretreatment of the anode. The method of manufacturing an organic light emitting display device according to the present invention is characterized by having a waiting time of about 1 minute or more in the hole injection layer forming chamber after the formation of the anode and the progress of plasma pretreatment.

The hole injection layer forming chamber is preferably maintained in a high vacuum state.

Subsequently, as illustrated in FIG. 3C, the hole injection layer 12 is evaporated on the anode 11 to form a film.

In this case, the hole injection layer 12 is the hole injection layer 12 and the anode 11 due to the uniformity of the organic molecules 12a and the component of the trace amount of the hole injection layer component partially contained on the surface of the anode 11 The adhesion between the layers is increased to improve the interfacial film quality.

In this process, the hole injection layer forming organic material is uniformly supplied to the substrate side in the hole injection layer forming chamber, and unlike the atmospheric state, the organic material source for forming the hole injection layer onto the substrate 10 is toward the substrate side. Uniformly supply organic molecules.

In this case, the energy barrier Φ h between the anode 11 and the hole injection layer 12 is modified as follows.

Φh = IP-Φm + △ (Φm: work function of anode, IP: difference between vacuum level of hole injection layer and ground energy level, △: difference of vacuum level between anode and hole injection layer)

In this case, the manufacturing method of the organic light emitting diode display of the present invention increases the work function of the anode through the plasma pretreatment and the hole injection layer forming chamber for a predetermined time, thereby reducing the energy barrier? It can be.

Here,? Representing the difference in vacuum level between the anode and the hole injection layer occurs naturally due to the material difference between the hole injection layer of the anode and the organic semiconductor component regardless of the plasma pretreatment or the chamber atmosphere. This causes the charge transfer between the two materials at the metal / organic semiconductor junction interface, the free electron wave function of the metal surface due to the adsorbed organic molecules, and the value is almost identical regardless of the above treatment. . The manufacturing method of the organic light emitting diode display of the present invention is not intended to change the vacuum level difference between the anode and the hole injection layer, but lowers the Fermi level on the surface of the anode, thereby reducing the work function of the anode. The purpose is to increase the.

Meanwhile, as shown in FIG. 1, after the formation of the hole injection layer described above, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially formed.

Here, the hole transport layer, the organic light emitting layer, the electron transport layer, the electron injection layer may be formed separately from each other, as shown, or may be formed as a single layer by mixing a host and a dopant of the component performing the function of each layer, You may divide and form two or more layers of each layer. The stack structure is not limited to a specific structure, and may be selectively applied to a level that does not impair the interfacial properties between the metal and the organic semiconductor.

4A and 4B are cross-sectional views illustrating a process method of the present invention compared with the manufacturing method of the OLED display.

As shown in FIG. 4A, the process method of Comparative Example first prepares the substrate 100 and then deposits the anode 110 on the substrate 100 through a deposition method such as sputtering. In this case, the surface of the anode 110 is non-uniform irregularities are generated, even if the plasma pre-treatment on the surface of the anode 110 to improve the film quality, as shown in Figure 4b, to form a hole injection layer 111 When the hole injection layer 111 is formed along the unevenness of the surface of the anode 110, the surface of the hole injection layer 111 is not free from nonuniformity of the surface of the anode 110.

5 is a diagram illustrating energy levels at a junction interface between an anode and an organic material layer manufactured by using the method of manufacturing an organic light emitting display device of the present invention.

The energy level characteristics between the interface between the anode and the organic material layer manufactured using the manufacturing method of the organic light emitting diode display of the present invention and the manufacturing method of the comparative example will be described with reference to FIG. 5.

As shown in FIG. 5, the manufacturing method (solid line display) of the organic light emitting display device of the present invention shows that the Fermi level of the anode is lower than the manufacturing method (dashed line display) of the comparative example. That is, it can be seen that the hole injection energy barrier Φh between the hole injection layer of the organic material and the anode falls to about 1/2 level. And, this means that the work function Φ m at the anode becomes large.

In this case, the hole injection layer has no energy level difference compared to the manufacturing method of the comparative example through the same manufacturing process, and in the manufacturing method of the organic light emitting display device of the present invention, pretreatment of the plasma surface of the anode 11, It can be seen that there is a change in the Fermi level drop of the anode 11 due to the improvement of the film quality of the anode 11 to the atmosphere in the hole injection layer forming chamber for a predetermined time or more.

On the other hand, not described symbol Φ e means the difference between the Low Unocuupied Molecular Orbital (LUMO) and Fermi level of the hole injection layer, EA means the difference between the vacuum level of the hole injection layer and the energy level of the hole injection layer.

FIG. 6 is a graph illustrating embodiments in which a waiting time of a hole injection layer forming chamber is changed when a method of manufacturing an organic light emitting display device is used, and a lifespan change according to a comparative example.

Table 1 shows the conditions and voltage (Volt (V)), light intensity (Cd / A), lighting efficiency (lm / W), color coordinates (CIEx, CIEy), and quantum efficiency (EQE) corresponding to FIG. 6. to be.

Referring to FIG. 6 and Table 1, the lifespan and characteristics of the organic light emitting diode display will be described in the case of using the manufacturing method of the organic light emitting diode display and the comparative example.

Here, Ref. Is a value after the process is performed in the hole injection chamber without waiting time, as in the comparative examples of FIGS. 4A and 4B. In this case, the life of the organic light emitting diode display is observed to be less than 20 hours.

Also, as in the method of manufacturing the organic light emitting display device of the present invention, when the hole injection layer forming chamber (HIL chamber) is waited for 20 minutes, 40 minutes, and 60 minutes, the Ref. There is no difference in the service life and conditions, and if it is 40 minutes or more, it is 400 hours or more. It can be confirmed that there is an effect of 20 times longer than the life.

In addition, there is a slight increase in the lifespan of the substrate in which the anode is formed in the vacuum chamber instead of the hole injection layer forming chamber for 40 minutes, but this is not significantly improved in the conditions and lifespan of the Ref. Instead, when the substrate was placed in the hole transport layer forming chamber (HTL chamber) for 40 minutes, there was a slight increase in lifespan compared to the vacuum chamber, but the same effect as the hole injection layer forming chamber was not obtained.

In FIG. 6, the horizontal axis represents time h, and the vertical axis represents 80 to 100% of light emission efficiency.

The conditions and voltage (Volt (V)), light intensity (Cd / A), lighting efficiency (lm / W), color coordinates (CIEx, CIEy), and quantum efficiency (EQE) are examined. As shown in the present invention, the driving voltage is lowest when the chamber is formed in the hole injection layer for 40 minutes, and the light intensity (7.1 Cd / A) and the lighting efficiency (5.5 lm / W) and the quantum efficiency (8.8%) are above a certain level. Can be obtained.

As described above, the above-described experimental value is a result value of the stack structure as shown in FIG. It can be expected that even if it has, the above-described effect can be obtained.

The waiting time of the predetermined time is not limited to the above-described experimental example. In the present invention, it is noted that the adhesion between the anode and the hole injection layer is improved when the hole injection layer is not formed on the anode immediately after loading in the chamber in accordance with the change of the stack structure, and when the hole injection layer has a predetermined waiting time.

Therefore, as in the organic light emitting diode display of the present invention, after the metal deposition in the chamber for forming the organic material layer adjacent to the metal and waiting for a predetermined time or more, the process of depositing the organic material layer makes the interface property between the metal and the organic material layer uniform. In addition, it can be seen that the interlayer adhesion can be improved and the energy barrier of hole injection or electron injection from metal to organic layer can be lowered.

Meanwhile, in the above-described embodiment, only the interface between the anode and the hole injection layer has been described. However, the same treatment may be expected at the interface between the electron injection layer and the cathode to lower the electron injection barrier.

In addition, when an organic layer other than the hole injection layer (for example, a hole transport layer or an organic light emitting layer) is adjacent to the anode, the same or similar effect may be expected by waiting the substrate in the chamber for forming the organic layer.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

10: substrate 11: anode
12: hole injection layer 13: hole transport layer
14 organic light emitting layer 15 electron transport layer
16: electron injection layer 17: cathode
50: organic semiconductor

Claims (4)

Depositing an anode on the substrate;
Plasma pretreatment of the anode surface after the anode deposition;
Waiting for at least one minute after loading the substrate on which the anode is deposited into the hole injection layer forming chamber;
Depositing a hole injection layer on the anode in the hole injection layer forming chamber; And
And sequentially forming an organic light emitting layer and a cathode on the hole injection layer. The method of claim 1,
After the substrate on which the anode is deposited is loaded into the hole injection layer forming chamber, the air injecting layer forming organic molecules remaining in the hole injection layer forming chamber adhere to the surface of the anode in a step of waiting for at least 1 minute. A method of manufacturing an organic light emitting display device. The method of claim 2,
And waiting at least one minute after loading the substrate on which the anode is deposited into the hole injection layer forming chamber, wherein the hole injection layer forming chamber maintains a high vacuum state. The method of claim 1,
In the forming of the hole injection layer on the anode in the hole injection layer forming chamber, the organic material for forming the hole injection layer is uniformly supplied to the substrate in the hole injection layer forming chamber. Method of manufacturing the device.

Images