KR100493531B1 - Formation method for anode of oxide film in organic electroluminescent device and organic electroluminescent device comprising anode of oxide film - Google Patents

Abstract

The present invention relates to a method of forming an anode electrode by varying the surface composition of the transparent oxide electrode layer in the organic light emitting device and to an organic light emitting device including the prepared transparent oxide electrode layer as an anode layer. In the organic light emitting device according to the present invention, the anode electrode layer is selected from the group consisting of aluminum oxide, zinc, tin, indium, boron and gallium. A doped oxide electrode layer having a structure doped with a dopant selected from the group; And a surface oxide layer formed by atomic layer deposition on the doped oxide electrode layer. According to the present invention, since the work function of the anode can be adjusted, it is easy to manufacture anodes suitable for various device structures, and excellent properties even in low temperature processes can be easily applied to the manufacture of organic light emitting devices using plastic as a substrate. .

Description

A method of forming an oxide anode electrode of an organic light emitting device and an organic light emitting device including an oxide anode electrode layer.

The present invention relates to a method of forming an oxide electrode layer of an organic light emitting device and to an organic light emitting device comprising an oxide electrode layer as an anode. More particularly, the present invention relates to a method of forming an oxide electrode layer of an organic light emitting device, in particular, a surface of an oxide electrode layer in various compositions by atomic layer deposition, and an organic light emitting device including such an oxide electrode layer as an anode electrode.

In the high information age of the 21st century, the research and development of new futuristic display devices is of paramount importance. In particular, technologies related to the development of materials such as semiconductors and displays along with the ubiquitous revolution have become a key issue.In particular, organic light emitting diodes (OEL, Organic Light Emitting Diode; OELD) It is getting attention.

The organic light emitting device is well known as a flat panel display capable of implementing a scroll type display technology, which is a next generation display device, and is currently being used as an LCD back-light or a portable display device based on a glass substrate. An organic light emitting device is a device in which electrons and holes generate electron-hole pairs, and light is generated through the process of falling to the ground state. In addition, the organic light emitting device has all three primary colors of light at a low driving voltage of less than 10V, the organic monomolecule is excellent in achieving high resolution and natural colors, and in the case of organic polymers, large area displays can be manufactured at low cost. This has the advantage of being flexible, and having a fast response time.

Looking at the structure of the organic light emitting device, as an injection type thin film device made of a light emitting layer and a transport layer, carrier injection type light emitting device in which all carriers that contribute to light emission are injected from an external electrode, and carrier injection and carrier movement are easier than anything else. One material is needed. Among the electrodes, an electrode having a high work function (anode) is used as a hole injection electrode and an electrode having a low work function (cathode) is used as an electron injection electrode. In order to increase the efficiency of the OLED, it is widely known that the work function of these electrodes should be well matched with the energy of the molecular orbital of the organic light emitting layer. In addition, it is also important to control not only the work function of each electrode but also the amount of hole and electron injection so that light is emitted from the light emitting layer without losing these carriers.

Among the electrode materials, metals such as magnesium (Mg), indium (In), calcium (Ca), aluminum (Al), and alloys thereof are mainly used as the cathode. In the case of cathode electrodes, many studies have been made on improving the efficiency of an organic light emitting device by using a multi-layer structure of a metal thin film having a low work function or an easy structure for electron injection, whereas the research on anode electrodes has been actively conducted recently. It's bad.

The work function of the anode has an effect on the efficiency of injecting holes into the organic layer.K. Sugiyama et al. Studied the change of chemical composition according to the surface treatment of ITO and the effect of the work function. Therefore, it has been reported that the work function changes by being affected by the chemical composition of the anode. (Journal of Applied Physics, Vol. 87, pp. 295, 2000) Meanwhile, S.M. Tadayyon et al. Tried to provide a high work function ITO by depositing a metal with a high work function such as Au or Pt on the surface of the ITO. (J. Vac. Sci. Technol. A. 17 (4) Jul. Pp. 1773)

As the anode of the OLED, a metal electrode having a high work function may be used in addition to the transparent electrode. In this case, the emitted light is not directed toward the lower transparent substrate but is directed to the opposite direction of the substrate, that is, to the top (cathode). TA Beierlein et al. As various techniques relating to the structural transformation of the anode; 1) using Ti / Al anode electrode on quartz substrate and depositing ITO on top of it; 2) using Al electrode as anode on silicon substrate and depositing InNO _x on top of it; 3) silicon A technique of depositing Al-Cu / Ni / NiO _x in turn and depositing V ₂ O ₅ as a final anode conversion layer has been reported. (US 6,501,217) All these techniques are aimed at controlling the energy level of the molecular orbitals of the materials involved in the work function and organic light emission on the anode side and also the amount of carriers injected from both electrodes.

The above-listed techniques relate to the conversion of properties through surface treatment in the case of ITO, and the introduction of other barrier layers in the case of metal anodes. There are no reports of growing technology. In particular, ITO, the most widely used hole injection electrode, is mainly deposited by sputtering and has a thickness of about 100 to 200 nm. ITO has an advantage of optical transparency, but it is easy to control when depositing a thin film. It has the disadvantage that the value of the target is expensive. In particular, the thin film is formed in the form of large crystal grains due to the characteristics of the material. As a result, the surface roughness is large, and thus, in order to obtain a flat ITO surface, mechanical (CMP) polishing is inconvenient. In particular, when using a plastic substrate it is difficult to obtain the ITO electrode properties of excellent properties because the ITO deposition temperature must be lowered.

As an oxide thin film electrode other than ITO, a study on ZnO: Al, ZnO: Ga or ZnO: B by atomic layer deposition has been reported. ZnO-based oxide thin films reported to date are mainly studied for low temperature process, surface roughness, and sheet resistance for solar cell applications. For example, V. Lujala et al. Reported that Al-doped ZnO thin films were deposited at 120 to 350 ° C. to have a sheet resistance of 10 Ω / □ at a thickness of 1 μm (Applied Surface Science Vol. 82/83 , pp. 34-40, 1994). W. Wenas et al. Reported a ZnO: B thin film with a sheet resistance of 10 Ω / □ at a thickness of 2 μm at 150 ° C. (J. Appl. Phys., Vol. 70, No. 11, pp. 7119-7123, 1991), AW Ott et al. Have reported a ZnO: Ga thin film on a PET plastic with a resistivity value of 1.4 × 10 ⁻³ μm cm. B. Sang et al. Reported a study on lowering the resistance of ZnO: B and changing the surface roughness characteristics by using a mixture of atomic layer deposition and vapor chemical vapor deposition (Jpn. J. Appl). Phys. Vol 1, 37 (1998) pp. L206). However, the above techniques are all studies on the electrical properties by the average composition of the entire oxide thin film containing ZnO as a parent material, the technology of the electrical and material properties through the change of dopant composition in the ZnO oxide electrode thin film and the anode of the organic light emitting device There is no report on the characteristics as an electrode.

In the anode layer of the organic light emitting device, an oxide electrode layer is formed through a surface reaction, and the surface oxide layer is formed in various compositions by using an atomic layer deposition method on the oxide electrode layer, thereby varying the work function. It is an object of the present invention to provide a method for producing an anode layer which can be controlled and excellent in low temperature processes.

In addition, an object of the present invention is to provide an organic light emitting device including an anode electrode layer having a surface oxide layer as described above, and a flat display device including the same.

The present inventors have intensively studied in order to achieve the above technical problem, and when the anode layer of the organic light emitting device is formed of an oxide electrode, the electrode surface is formed by various methods by atomic layer deposition, The present invention has been completed in view of the fact that an anode layer which can be arbitrarily controlled and has excellent properties even in a low temperature process can be prepared.

The present invention has the following configuration.

Repeating step (a) of forming the oxide base material layer on the substrate on which the substructure is formed by using the surface chemical reaction or the mixed deposition method of the surface chemical reaction and the vapor phase chemical reaction and the oxide base material layer as the dopant After the step (b) of doping is repeated b times, the process of repeating the steps (a) and (b) a and b times again is repeated n times to form a doped oxide electrode layer. Stage 1; And a second step of forming a surface oxide layer on the surface of the formed oxide electrode layer by an atomic layer deposition method. Here, the number of repetitions of a, b, and n depends on the type of the parent material and the dopant, and the thickness of the desired oxide electrode layer, and forms the electrode thin film in a thickness of 1000 to 5000 ohms, so that the thickness can be obtained. It is arbitrarily adjusted in consideration of the size of the material and the dopant atoms.

The present invention also provides an organic electroluminescent device comprising a substrate, an anode layer, a cathode layer and a light emitting layer, wherein the anode layer is selected from the group consisting of oxides of zinc oxide, tin oxide and indium oxide formed using surface chemical reactions. A doped oxide electrode layer having a structure doped with a dopant selected from the group consisting of aluminum, zinc, tin, indium, boron and gallium; And a surface oxide layer formed by atomic layer deposition on the doped oxide electrode layer.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

First, referring to Figures 1 and 2 will be described the structure of the organic light emitting device used in the present invention.

1, the anode electrode 110, the hole injection layer 120, the hole transport layer 130, and the organic light emitting layer 140 are disposed on the substrate 100. It can be seen that the electron transport layer 150, the electron injection layer 160, and the cathode electrode layer 170 are sequentially stacked. At this time, the substrate can be used without limitation, such as a glass substrate, a plastic substrate.

The hole injection layer 120 serves to supply holes supplied from the anode electrode 110 to the hole transport layer hole transport layer, and the hole transport layer 130 is a polyamine (9-vinylcarbazole), which is a diamine derivative TPD and a photoconductive polymer. ), NPD, MTDATA, PEDOT / PSS, and the like, using an oxadiazole derivative or AlQ as the electron transport layer 150, and through the combination of these transport layers to increase the quantum efficiency, the carriers are not directly injected through the transport layer The driving voltage can be lowered through the two-step injection process. In addition, when the electrons and holes injected into the light emitting layer 140 are moved to the opposite electrode via the light emitting layer 140, it is possible to control recombination by blocking the opposite transport layer. Through this, the luminous efficiency can be improved.

The light emitting layer 140 is a polymer organic electroluminescent material of monomolecular organic electroluminescent materials such as AlQ ₃ , anthracene, and PPV (poly (p-phenylenevinylene)), PT (polythiophene), polyfluorene, or derivatives thereof. Luminescent materials and the like can be used.

The electron transport layer 150 and the electron injection layer 160 are formed on the opposite side of the hole injection layer 120 and the hole transport layer 130 with the light emitting layer 140 interposed therebetween. The anode electrode layer 110 of the organic light emitting device injects holes into the light emitting layer 140 through the hole transport layer 130, and the cathode electrode 170 injects electrons into the light emitting layer 140 through the electron injection layer 160. By injecting electron-hole pairs in the light emitting layer 140 and then extinguished and emits light by emitting energy. The cathode electrode 170 is a metal having a low work function as an electrode for electron injection, and Ca, Mg, Al, and the like are used, and a buffer layer such as LiF, CsF, etc. may be formed for easier electron injection. The reason for using the metal having a low work function as the electron injection electrode is to obtain a high current density in electron injection by lowering a barrier formed between the cathode electrode 170 and the emission layer 140. Because it can. Therefore, while Ca having the lowest work function shows high efficiency, Al has a relatively high work function and thus has low efficiency. However, Ca has a problem of being easily oxidized by oxygen or moisture in the air, and Al has a stable property in the air.

Next, an organic light emitting device that emits light upwards will be described. Two structures are possible for an organic light emitting device that emits light upward.

One is to change the substrate into an opaque substrate in the structure of FIG. 1 and to laminate it on the opaque substrate in a reverse order to that of FIG. That is, the order of the cathode electrode 170, the electron injection layer 160, the electron transport layer 150, the light emitting layer 140, the hole transport layer 130, the hole injection layer 120 and the anode electrode 110 on the opaque substrate Stacked structure (n-type).

The other is stacked on the opaque substrate in the same structure as the device of Figure 1 emitting below, but the thin film is deposited as thin as possible to the upper metal electrode (cathode electrode) as transparent as possible (p-type) to be. This structure is shown in FIG. That is, on the opaque substrate 200, the anode electrode 110, the hole injection layer 120, the hole transport layer 130, the light emitting layer 140, the electron transport layer 150, the electron injection layer 160, and the cathode electrode ( 170, but the cathode 170 is deposited as thin as shown in FIG. 2, and then the transparent electrode 210 is deposited thereon. Description of each layer is the same as the description of the laminated film of the bottom emission type organic light emitting diode in FIG.

However, the case where the transparent oxide electrode according to the present invention is used as the anode layer is most effective in the case of the top emission type, in particular the top emission type of p-type. This is because, in the case of n-type, the organic layer below the electrode may be damaged by the precursor used for depositing the transparent oxide electrode.

The method for forming an anode electrode according to the present invention consists of first forming a parent material layer, then doping with a dopant to form a doped oxide electrode layer, and forming a surface oxide layer on the surface of the formed oxide electrode layer by atomic layer deposition. .

Hereinafter, the atomic layer deposition method will be described in more detail by using ZnO as a base material and Al as a dopant as an example.

The oxide electrode can be deposited by using an atomic layer deposition method at 70 to 400 ° C. In this case, the precursor of zinc (Zn) can be easily deposited with a thin film of diethylzinc or dimethylzinc. use. In the case of using aluminum as a dopant, the precursor of aluminum is mainly trimethylaluminum or triethylaluminum, which is stable and relatively inexpensive doping, and in the case of using boron as a dopant, the precursor of boron In the case of low diborane (B ₂ H ₆ ), gallium, other organometallic precursors may be used in addition to trimethylgallium (Ga (Me) ₃ ) or triethylgallium (Ga (Et) ₃ ). Further, the oxygen precursor is for example the case of the use of methanol, ethanol, isopropyl alcohol, such as alcohol, water, or ozone (O _3), and plasma deposition is used in an oxygen, water, alcohol or plasma.

The kind of atomic layer vapor deposition method used by this invention is not specifically limited. Atomic layer deposition is largely divided into traveling wave reactor type and plasma-enhanced atomic layer deposition. In the latter case, the plasma generator is divided into a remote plasma atomic layer deposition method and a direct plasma atomic layer deposition method. In the case of transparent oxide, the use of water as a traveling wave reactor type is better than using an ozone or plasma source, and in the case of mass production, the traveling wave reactor type can mount several dozen substrates at once. This would be more advantageous.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

In the following examples, a zinc oxide thin film was deposited at 70 to 300 ° C. using zinc oxide as a parent material and doped with aluminum as a dopant. However, ZnO, SnO, and In ₂ O ₃ were selected as the base material of the oxide electrode layer. The dopant may be used as one or two or more selected from Al, B, Ga, Sn, In. Usually, when the base material is ZnO, Al, B, Ga, etc. are used, and when the base material is In ₂ O ₃ , Sn is used, but ZnO: In (In doped ZnO), ZnO: In / Sn (In Sn doped) ZnO), SnO: Zn / In (Zn In doped SnO), InO: Ga can also be formed by the same method as in the following embodiments of the present invention.

A traveling atomic layer deposition apparatus capable of mounting a 12 " x14 " substrate was used. After forming various electrode surface layers, the respective work functions and luminous efficiency were measured.

Example 1

1. Formation of Doped Oxide Electrode Layer

(a) ZnO oxide base material layer formation step

First, the substrate on which the sub-step to which the anode electrode should be formed is completed is placed in a chamber of a traveling atomic layer deposition apparatus whose internal temperature is maintained at 180 °.

Into the chamber was injected 1.65 seconds of diethyl zinc vapor, the temperature of which was maintained at 18 degrees with nitrogen or argon as the carrier gas, to adsorb the Zn-precursor reactant onto the substrate surface. Thereafter, the gas valve of the chamber was opened and nitrogen or an inert gas was injected at a flow rate of 200 sccm for 1.65 seconds to remove molecules not adsorbed to the substrate surface in the Zn-reactant.

The gas valve of the chamber was opened and H ₂ O gas maintained at 18 degrees was injected with carrier gas at a flow rate of 200 sccm for 1.65 seconds. The gas valve of the chamber was opened and nitrogen or an inert gas was injected to remove the volatile reaction product between the Zn-precursor containing H ₂ O molecules and H ₂ O.

This process was repeated 19 times to obtain a 4.4 nm thick ZnO thin film. It is usually repeated 10 to 30 times to obtain ZnO of the desired thickness.

(b) Al dopant addition step

Into the chamber, trimethylaluminum vapor, maintained at 16 degrees Celsius at a flow rate of 100 sccm with nitrogen or argon as the carrier gas, was injected into the chamber for 0.55 seconds to adsorb the Al-precursor reactant onto the deposited oxide oxide surface. Then, the gas valve of the chamber was opened and nitrogen or an inert gas was injected to remove all the non-adsorbed molecules on the ZnO surface of the Al-precursor reactant.

The gas valve of the chamber was opened and H ₂ O gas was injected for 1.65 seconds to grow an aluminum oxide thin film by surface reaction with the Al-precursor reactant adsorbed on ZnO, producing volatile byproducts. Thereafter, the gas valve of the chamber was opened and nitrogen or an inert gas was injected to remove the volatile reaction product between the Al-precursor containing H ₂ O molecules and H ₂ O.

Thereafter, a total of 49 repetitions were performed {(a)-19 times and (b)-1 time}.

The execution of steps (a) and (b) is shown in FIG. 3 in the form of a flowchart.

2. Formation of Surface Oxide Layer (ZnO Layer)

In order to form the electrode surface with the ZnO film, step (a) was finally repeated 19 times to form ZnO on the surface. A schematic cross sectional view of the formed anode layer is shown in FIG. 4. As a result, an anode electrode in which the electrode surface oxide layer was made of ZnO was obtained.

The thickness of the transparent oxide thin film by the atomic layer deposition method according to Example 1 may be represented by the following formula.

T (total thickness of ZnO: Al layer) = n (a × (growth rate of ZnO) + b × (Al ₂ O ₃ Growth rate)}

+ c × (growth rate of ZnO) + d × (Al ₂ O ₃ Growth rate)

In this case, a means the number of repetitions of step (a) in the step of forming the oxide base material layer, b means the number of repetitions of step (b) in the step of forming the parent material layer, and n is {( It shows the total number of repetitions of a) step repetition + (b) step repetition}. C represents the number of repetitions of step (a) in the surface oxide layer forming step, and d represents the number of repetitions of step (b) in the surface oxide layer forming step.

In Example 1, a is 19, b is 1, c is 19, d is 0, and n is 49.

In Example 1, the number of growths (b) of aluminum oxide was set to 1, depending on the number of times the ZnO growth process and the entire Al ₂ O ₃ doping process were performed. Accordingly, the sheet resistance value changes. At this time, the deposition time according to one cycle depends on how much the injection amount of the precursor, and also, the injection amount of the precursor is an amount depending on the size of the substrate. In the case of forming the ZnO thin film by the atomic layer deposition method in the order of the above process, a uniform thin film can be formed on the large-area substrate, and the precursor is inexpensive, which is advantageous for mass production.

A schematic cross-sectional view of the anode electrode prepared according to Example 1 is shown in FIG. 4. A dopant oxide layer 420 is formed between the oxide base material layer 410 of the anode layer, and a ZnO layer, which is an oxide base material layer, is formed on the surface.

Example 2

1. Formation of Doped Oxide Electrode Layer

In the same atomic layer deposition method as in Example 1, steps (a) and (b) were repeated 19 times and once, respectively, and the total number of repetitions of {step (a) + step (b)) was 50. . That is, in Equation 1, a = 19, b = 1, n = 50.

2. Surface oxide layer (Al ₂ O ₃  Formation stage)

In order to deposit aluminum oxide on the electrode surface, step (b) was repeated twice. In Equation 1, c = 0 and d = 2. A schematic cross-sectional view of the anode electrode thus manufactured is shown in FIG. 5. A dopant oxide layer 420 is formed between the oxide base material layer 410 of the anode layer, and the surface of the oxide base material layer Al ₂ O ₃ is formed.

When the step (b) is performed once on the ZnO before the oxide layer on the surface is formed, since the mono-monolayer is not formed, the step (b) is repeated in order to completely form the surface of the transparent electrode by aluminum oxide. The number of times is preferably performed two or more times. When the number of times of deposition is repeated seven or more times, since the etching of the transparent electrode is not easy, the number of times is preferably within six times. When the surface of the transparent electrode is formed of aluminum oxide, the surface roughness characteristics and work function characteristics are further increased.

Example 3

1. Formation of Doped Oxide Electrode Layer

In the same atomic layer deposition method as Example 1, steps (a) and (b) were repeated 19 times and once, respectively, and the total number of repetitions of {repeat (a) + repeat (b)} was 47. . That is, in Equation 1, a = 19, b = 1, n = 47.

2. Formation of surface oxide layer (ZnO layer oriented in c-axis)

In order for the c-axis oriented ZnO to be formed into the surface oxide layer, the embodiment of step (a) was changed slightly as follows.

Into the chamber was injected 1.65 seconds of diethyl zinc vapor, the temperature of which was maintained at 18 degrees with nitrogen or argon as the carrier gas, to adsorb the Zn-precursor reactant onto the substrate surface. Thereafter, the gas valve of the chamber was opened and nitrogen or an inert gas was injected at a flow rate of 200 sccm for 1.65 seconds to remove molecules not adsorbed to the substrate surface in the Zn-reactant.

Thereafter, oxygen (O ₂ ) was injected for 1.65 seconds without a carrier gas.

Soon the gas valve of the chamber was opened and H ₂ O gas maintained at 18 degrees was injected with carrier gas at a flow rate of 200 sccm for 1.65 seconds. The gas valve of the chamber was opened and nitrogen or an inert gas was injected to remove the volatile reaction product between the Zn-precursor containing H ₂ O molecules and H ₂ O.

This process is the addition of the intermediate oxygen injection step in step (a) of the previous step of forming the surface oxide layer, which is shown as step (a ') for convenience, and the number of times to repeat step (a') The number of times of repeating is denoted by c 'in the above equation for convenience. The procedure (a ') was repeated 70 times to obtain a ZnO thin film oriented in the c-axis having a thickness of 13.2 nm.

In Equation 1, c '= 70 and d = 0. It is preferable to make c 'value at this time into 200 or less. At this time, the ZnO thin film oriented in the c-axis has a flatter surface than the surface roughness of the ZnO thin film oriented in the a-axis, and the work function is further increased.

A schematic cross-sectional view of the anode electrode thus manufactured is shown in FIG. 6. A dopant oxide layer 420 is formed between the oxide parent material layer 410 of the anode layer, and a ZnO layer 610 is oriented in the c-axis.

Example 4

1. Formation of Doped Oxide Electrode Layer

In the same atomic layer deposition method as Example 1, steps (a) and (b) were repeated 19 times and once, respectively, and the total number of repetitions of steps (a) and (b) was 47. That is, in Equation 1, a = 19, b = 1, n = 47.

2. Surface oxide layer (Al ₂ O ₃ Formation of this massively doped ZnO layer)

Subsequently, in order to form a ZnO surface oxide layer doped with a larger amount of Al ₂ O ₃ than the doped oxide electrode layer, step (a) was repeated five times and step (b) once a total of twelve times. In this case, the work roughness is further increased as compared with the first embodiment, while the surface roughness characteristics are lowered. A schematic cross sectional view of the anode electrode formed in accordance with Example 4 is shown in FIG. 7. A dopant oxide layer 420 is formed between the oxide base material layer 410 of the anode layer, and a dopant (Al ₂ O ₃ ) layer is densely arranged on the surface portion of the oxide base material layer doped to the base material layer. It can be seen that.

In the above embodiments, the number of repetitions was adjusted to make the thickness of the formed oxide electrode layer similar. The surface oxide layer was made to be about 5 to 30 nm in total thickness of the anode.

The characteristics of the anode electrodes prepared according to Examples 1 to 4 were measured.

As a result of measuring the work function, when manufactured according to Example 1: 4.53 eV, manufactured according to Example 2: 4.77 eV, manufactured according to Example 3: 4.60 eV, prepared according to Example 4. When measured: 4.69 eV.

The anode according to Example 2 with the aluminum oxide film exposed on the surface was found to have the highest work function. Therefore, when an anode having a high work function is required by adjusting the band gap with the hole injection layer, the step (B) of Example 2 may be selected, and the efficiency is improved by manufacturing the device by adjusting the band gap with each layer. Can produce high OLED

In order to show the characteristics of surface roughness, the surface of the anode electrode according to Example 1 and the surface of the anode electrode according to Example 3 are shown in FIGS. 8A and 8B, respectively. The Rms roughness of the anode electrode surface according to Example 1 was 21.9 GPa, and the average roughness was 11.7 GPa. The Rms roughness of the surface of the anode electrode prepared according to Example 3 was 17.0 kPa, and the average roughness was 12.0 kPa. That is, by changing the composition of the anode surface it can be seen that there is an effect that can be converted to adjust the roughness characteristics.

In the present invention, the OLED efficiency including the anode manufactured in Example and the luminance characteristics of the OLED device of the known anode are shown in FIG. 9, and the efficiency of external quantum is shown in FIG. What was used as a comparative example was produced using the commercially available Sanyo Paik ITO as an anode.

As shown in FIG. 9, the OLED device including the anode manufactured by changing the composition of the surface according to the present invention was evaluated to have better EL characteristics than that prepared according to the comparative example. In addition, as shown in FIG. 10, the efficiency of the OLED device including the anode according to the present invention was found to be higher than that of the comparative example.

As another application example of the present invention, the portion of the surface except for the surface portion may be formed by the vapor chemical vapor deposition and the surface portion to be changed by the atomic layer deposition method described above may reduce the anode deposition time. In addition, atomic layer deposition methods such as a mixing of a traveling type and a plasma type may also be mixed with each other for deposition of each oxide electrode thin film. In addition, when the ITO thin film is manufactured by atomic layer deposition, the same effect is applied in the above invention by replacing the base material corresponding to ZnO with tin oxide (SnO ₂ ) and dopant alumina with indium oxide (In ₂ O ₃ ). Can be obtained. Therefore, although the technical idea of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention forms a doped oxide electrode layer by using a surface chemical reaction or a mixture of surface chemical reactions and vapor phase chemical vapor deposition of precursors containing thin film constituent atoms, and then the composition of the surface oxide layer is Forming or inducing a crystal change of the surface has the effect of improving the device characteristics such as changing the work function and changing the mobility of the holes to improve the efficiency of the organic light emitting device.

In addition, since the work function of the anode electrode can be arbitrarily adjusted, it is possible to manufacture the anode electrode suitable for various device structures. The anode according to the present invention has excellent properties even in low temperature processes, and thus can be easily applied to manufacturing OLED devices using plastic as a substrate.

1 is a schematic cross-sectional view of an organic light emitting device having a bottom emission type multilayer structure.

2 is a schematic cross-sectional view of an organic light emitting device having a top emission type multilayer structure.

3 is a flowchart illustrating a method of forming an oxide electrode layer according to an embodiment of the present invention.

4 is a cross-sectional view of a transparent oxide electrode layer having a base material oxide layer formed on a surface of the oxide electrode layer in accordance with an embodiment of the present invention.

5 is a cross-sectional view of the transparent oxide electrode layer having a doped oxide layer formed on the surface of the oxide electrode layer in accordance with an embodiment of the present invention.

6 is a cross-sectional view of a transparent oxide electrode layer having a zinc oxide layer oriented in the C axis on the surface of the oxide electrode layer in accordance with an embodiment of the present invention.

7 is a cross-sectional view of a transparent oxide electrode layer having an oxide layer doped with a large amount of dopant on the surface of the oxide electrode layer in accordance with an embodiment of the present invention.

8a and 8b are photographs showing the surface roughness of the oxide electrode layer according to an embodiment of the present invention.

9 is a graph for comparing the luminance characteristics of the organic light emitting device and the conventional organic light emitting device formed according to an embodiment of the present invention.

10 is a graph for comparing external quantum efficiency characteristics of an organic light emitting device formed according to an embodiment of the present invention and a conventional organic light emitting device.

Explanation of symbols of the main parts of the drawings

100: transparent substrate 110: anode electrode

120: hole injection layer 130: hole transport layer

140: light emitting layer 150: electron transport layer

160: electron injection layer 170: cathode electrode

210: transparent electrode layer 410: oxide base material layer (ZnO)

420: dopant oxide layer (Al ₂ O ₃ ) 610: ZnO layer oriented in the c-axis

Claims (17)

In the anode electrode forming method of the organic light emitting device, Repeating step (a) of forming the oxide base material layer on the substrate on which the substructure is formed by using the surface chemical reaction or the mixed deposition method of the surface chemical reaction and the vapor phase chemical reaction and the oxide base material layer as the dopant After the step (b) of doping is repeated b times, the process of repeating the steps (a) and (b) a and b times again is repeated n times to form a doped oxide electrode layer. Stage 1; And And a second step of forming a surface oxide layer on the surface of the formed oxide electrode layer by atomic layer deposition. A method for forming an anode of an organic light emitting device. The method of claim 1, In the second step, the atomic layer deposition method includes one or two or more mixed deposition methods selected from a traveling wave reactor atomic layer deposition method including a showerhead method, a remote plasma atomic layer deposition method, and a direct plasma atomic layer deposition method. Anode electrode formation method of a light emitting element. The method of claim 1, Forming an oxide layer selected from zinc oxide, tin oxide and indium oxide as the oxide mother material layer, A method for forming an anode of an organic light emitting device, characterized in that used as the dopant is selected from the group consisting of aluminum, zinc, tin, indium, boron and gallium. The method of claim 1, Forming a zinc oxide layer as the oxide mother material layer, Aluminum is used as the dopant, Forming an undoped zinc oxide layer as said surface oxide layer. The method of claim 4, wherein Step (a) comprises the steps of placing the substrate in the reactor; Injecting a Zn-precursor with a carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, Step (b) comprises the steps of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, The second step is the anode electrode forming method of the organic light emitting device, characterized in that comprises the step (a) repeating a. The method of claim 1, Forming a zinc oxide layer as the oxide mother material layer, Aluminum is used as the dopant, And forming an aluminum oxide layer as said surface oxide layer. The method of claim 6, Step (a) comprises the steps of placing the substrate in the reactor; Injecting a Zn-precursor with a carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, Step (b) comprises the steps of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, The second step includes the step of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor. The method of forming an anode of an organic light emitting device according to claim 2, wherein the step (b) is repeated two or more times but less than seven times. The method of claim 1, Forming a zinc oxide layer as the oxide mother material layer, Aluminum is used as the dopant, Forming a c-axis oriented zinc oxide layer as the surface oxide layer. The method of claim 8, Step (a) comprises the steps of placing the substrate in the reactor; Injecting a Zn-precursor with a carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, Step (b) comprises the steps of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, The second step includes the step of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting oxygen; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor to repeat a series of processes less than 200 times. The method of claim 1, Forming a zinc oxide layer as the oxide mother material layer, Aluminum is used as the dopant, And forming a zinc oxide layer doped with a larger amount of aluminum than the oxide electrode layer as the surface oxide layer. The method of claim 10, Step (a) comprises the steps of placing the substrate in the reactor; Injecting a Zn-precursor with a carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And injecting an inert gas into the reactor, Step (b) comprises the steps of injecting the Al-precursor with the carrier gas into the reactor; Inert gas into the reactor; Injecting H ₂ O into the reactor; And (b) comprising the step of injecting an inert gas into the reactor, Wherein the second step, repeating the step (a) a / 2 to a / 10 times, and repeating the step (b) b times, the method of forming an anode electrode of an organic light emitting device. In the organic electroluminescent device comprising a substrate, an anode layer, a light emitting layer and a cathode layer, The anode layer is doped with a structure doped with a dopant selected from the group consisting of aluminum, zinc, tin, indium, boron and gallium in which an oxide parent material layer selected from zinc oxide, tin oxide and indium oxide is formed using a surface chemical reaction. Oxide electrode layer; And And a surface oxide layer formed by atomic layer deposition on the doped oxide electrode layer. The method of claim 12, The oxide base material layer is a zinc oxide layer, The dopant is aluminum, And the surface oxide layer is an undoped zinc oxide layer. The method of claim 12, The oxide base material layer is a zinc oxide layer, The dopant is aluminum, The surface oxide layer is an organic light emitting device, characterized in that the aluminum oxide layer. The method of claim 12, The oxide base material layer is a zinc oxide layer, The dopant is aluminum, And the surface oxide layer is a zinc oxide layer oriented in the c-axis. The method of claim 12, The oxide base material layer is a zinc oxide layer, The dopant is aluminum, And the surface oxide layer is a zinc oxide layer doped with a greater amount of aluminum than the oxide electrode layer. A flat panel display device comprising the organic light emitting device according to any one of claims 12 to 16.