KR101852196B1 - Organic light emitting diode device - Google Patents

Abstract

An organic electroluminescent device according to an exemplary embodiment of the present invention includes a substrate on which a thin film transistor is formed, an overcoat layer covering the thin film transistor on the substrate, a first electrode connected to the thin film transistor on the overcoat layer, A bank layer covering the overcoat layer, a light emitting layer disposed on the first electrode, and a second electrode opposing the first electrode, the second electrode being positioned on the light emitting layer, The bank layer may be composed of a siloxane-based organic material.

Description

[0001] ORGANIC LIGHT EMITTING DIODE DEVICE [0002]

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device using a siloxane-based organic material having high sensitivity and high reliability.

Flat panel displays (FPDs) are becoming increasingly important with the development of multimedia. In addition, various kinds of devices such as a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic light emitting diode A planar display of a branch has been put into practical use.

Of these, the organic electroluminescent element is a self-luminous element in a light emitting layer containing an organic substance, and has a response speed of 1 ms or less, a high response speed, low power consumption, Devices. The organic electroluminescent device comprises a first electrode, a second electrode, and a light emitting layer interposed therebetween on a substrate. Therefore, when a charge is injected into the light emitting layer formed between the second electrode, which is an electron injecting electrode, and the first electrode, which is a hole injecting electrode, electrons and holes are paired and then disappear and emit light.

Recently, an organic electroluminescent device has been developed as an active matrix structure including a thin film transistor on a substrate. In the active matrix structure, a thin film transistor is formed on a lower portion of the first electrode to transmit a driving signal to the first electrode, and an overcoat layer is formed between the first electrode and the thin film transistor to protect the thin film transistor while planarizing. However, the overcoat layer is vulnerable to outgas components and moisture generated from the organic material having low heat resistance by applying photoacryl, thereby lowering the reliability of the product.

In addition, in the case of a bank layer formed on the first electrode and partitioning a pixel of the organic electroluminescent device by exposing a part of the first electrode, polyimide is used, but a manufacturing cost is high due to high cost There is a problem.

The present invention provides an organic electroluminescent device using a siloxane-based organic material having high sensitivity and high reliability, which can improve the reliability of a product and reduce manufacturing cost.

According to an embodiment of the present invention, an organic electroluminescent device includes a substrate on which a thin film transistor is formed, an overcoat layer covering the thin film transistor on the substrate, a thin film transistor A bank layer covering the overcoat layer, a light emitting layer disposed on the first electrode, and a second electrode facing the first electrode, the second electrode being on the light emitting layer, And the overcoat layer and the bank layer may be made of a siloxane-based organic material.

The overcoat layer and the bank layer may be made of the same material.

The siloxane-based organic material may include a binder, a photosensitizer, a solvent, and an additive.

The binder may be a siloxane oligomer containing at least one selected from cyclodimethylsiloxane, dimethyldimethoxysilane, and methyltrimethoxysilane.

The binder may be included in an amount of 17 to 20 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The additive may include a tetrafluoroethylene or vinylidene fluoride monomer that is hydrogen-substituted with a carboxyl group or a hydroxy group.

The additive may be included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The additive may include a cross-linking agent and a surfactant.

A color filter may be disposed between the first electrode and the substrate.

The organic electroluminescent device may be a bottom emission structure in which light emitted from the light emitting layer is emitted to the substrate.

The organic electroluminescent device of the present invention has the advantage of being used simultaneously in the overcoat layer and the bank layer of the organic electroluminescent device by forming a siloxane organic material with high sensitivity and high reliability, thereby improving the reliability of the product and reducing the manufacturing cost .

1 is a plan view showing an organic electroluminescent device of the present invention.
2 is a circuit diagram showing subpixels of the organic electroluminescent device of the present invention.
3 is a cross-sectional view of a subpixel of an organic electroluminescent device according to an embodiment of the present invention.
4 is a schematic view showing that a siloxane and an acryl are combined with a photosensitizer, respectively.
5 is a photograph showing the shape of a hole of a siloxane organic material formed according to an experimental example of the present invention.

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

FIG. 1 is a plan view of an organic electroluminescent device of the present invention, and FIG. 2 is a circuit diagram of a subpixel of the organic electroluminescent device of the present invention.

1, an organic EL device 100 according to the present invention includes a display unit DA having a plurality of subpixels SP formed on a substrate 110 to display an image, A driving unit 30 for applying a driving signal to a plurality of sub-pixels SP is located. The organic electroluminescent device 100 of the present invention is composed of a plurality of subpixels SP, but for convenience of description, one subpixel SP will be described below.

2, the subpixel SP includes a switching thin film transistor T1 for transferring a data signal from a scan line Sn by a scan signal, a capacitor Cst for storing a data signal, a capacitor Cst for storing a data signal, A driving thin film transistor T2 for generating a driving current corresponding to a difference between the data signal and the power source voltage VDD and a light emitting diode OLED for emitting light corresponding to the driving current. In the present invention, a 2T1C structure including two thin film transistors and one capacitor has been described as an example, but the present invention is not limited thereto.

3 is a cross-sectional view of a subpixel of an organic electroluminescent device according to an embodiment of the present invention.

Referring to FIG. 3, an organic electroluminescent device 100 according to an embodiment of the present invention includes a gate electrode 115 on a substrate 110. The gate electrode 115 may be formed of any one selected from the group consisting of molybdenum (Mo), aluminum (Al), chrome (Cr), gold (Au), titanium (Ti), nickel (Ni), and copper Alloy, and may be composed of a single layer or multiple layers.

A gate insulating film 120 for insulating the gate electrode 115 is located on the gate electrode 115. The gate insulating film 120 may be formed of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a double layer thereof.

The semiconductor layer 125 is located on the gate insulating film 120 corresponding to the gate electrode 115. The semiconductor layer 125 may be made of amorphous silicon or polycrystalline silicon crystallized from amorphous silicon. Alternatively, the semiconductor layer 125 may be formed of any one of zinc oxide (ZnO), indium zinc oxide (InZnO), indium gallium zinc oxide (InGaZnO), and zinc tin oxide (ZnSnO). In addition, the semiconductor layer 125 may be made of a low molecular weight or high molecular weight organic material such as melocyanine, phthalocyanine, pentacene, and thiophene polymer.

A source electrode 130a and a drain electrode 130b which are electrically connected to the semiconductor layer 125 are disposed on the semiconductor layer 125. [ The source electrode 130a and the drain electrode 130b may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni and Cu. And may be made of any one selected or an alloy thereof.

The source electrode 130a and the drain electrode 130b may be formed of a double layer, and preferably the double layer is made of molybdenum (Mo) / aluminum-neodymium (Al-Nd), molybdenum (Mo) Or titanium (Ti) / aluminum (Al). The source electrode 130a and the drain electrode 130b may be formed of multiple layers, and preferably the multi-layer may be formed of Mo / Al / neodymium / molybdenum (Mo) or titanium (Ti) / Aluminum (Al) / titanium (Ti).

The passivation layer 133 is disposed on the thin film transistor T including the gate electrode 115, the semiconductor layer 125, the source electrode 130a, and the drain electrode 130b. The passivation layer 133 is formed of silicon oxide (SiOx) or silicon nitride (SiNx) to protect the lower TFT.

A color filter layer 135 is positioned on the passivation layer 133. The color filter layer 135 is formed on the passivation layer 133 to correspond to the first electrode 150 to be described later so that the white light emitted from the light emitting layer 160 is transmitted through the first electrode 150, 135, respectively. The color filter layer 135 may represent at least one color of red, green, and blue, and is shown as a red color filter layer in this embodiment.

The overcoat layer 140 is positioned on the passivation layer 133 including the color filter layer 135. The overcoat layer 140 may be a planarizing film that protects the underlying structure while relieving the step of the underlying structure. The overcoat layer 140 may be formed of a siloxane-based organic material. A detailed description thereof will be described later. A via hole 145 is formed in the overcoat layer 140 to expose a part of the source electrode 130a or the drain electrode 130b.

The first electrode 150 electrically connected to the source electrode 130a or the drain electrode 130b is positioned on the overcoat layer 140. [ The first electrode 150 may be formed of a material such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), indium gallium zinc oxide (IGZO), and graphene. And can be made of a transparent conductive film capable of transmitting light.

A bank layer 155 is disposed on the first electrode 150 and includes an opening 156 exposing the first electrode 150. The bank layer 155 may be a pixel defining layer which alleviates a step of the underlying structure and defines a light emitting region. The bank layer 155 is made of the same material as the above-mentioned overcoat layer 140, and a description thereof will be given later.

A light emitting layer 160 is disposed on the first electrode 150. The light emitting layer 160 is made of an organic material that emits white light, and can emit white light. A light emitting layer 160 is formed on the first electrode 150 described above in all subpixels. Therefore, the white light emitted from the light emitting layer 160 can be realized as red, green, and blue through the color filter described above.

An electron injection layer (EIL) and an electron transportation layer (ETL) are formed between the light emitting layer 160 and the first electrode 150 to facilitate the movement of electrons to the light emitting layer 160 As shown in FIG. A hole injection layer (HIL) and a hole transportation layer (HTL) may be formed between the light emitting layer 160 and the second electrode 170 to facilitate the movement of holes to the light emitting layer 160 As shown in FIG.

A second electrode 170 is disposed on the substrate 110 including the light emitting layer 160. The second electrode 170 may be made of a metal having a low work function such as aluminum (Al), silver (Ag), magnesium (Mg), calcium (Ca) In addition, the second electrode 170 may have a thickness of 500 to 2000 ANGSTROM to reflect light emitted from the light emitting layer 160.

As described above, the organic electroluminescent device 100 according to an embodiment of the present invention includes a bottom emission structure in which light emitted from the emission layer 160 is emitted to the substrate 110 on which the first lower electrode 150 is located. . Although the bottom gate type thin film transistor in which the gate electrode is located below the semiconductor layer is described as an example of the present invention, the top gate type thin film transistor . ≪ / RTI >

On the other hand, in the present invention, the above-mentioned overcoat layer and the bank layer are made of a siloxane-based organic material. Hereinafter, the siloxane-based organic material according to one embodiment of the present invention will be described in detail. 4 is a schematic view showing that the siloxane and acryl are bonded to the photosensitive agent, respectively.

The siloxane-based organic material according to one embodiment of the present invention is used in an overcoat layer and a bank layer of an organic electroluminescent device, and includes a binder, a photosensitizer, a solvent, and an additive.

The binder includes a siloxane-based material, and may be a siloxane oligomer. The siloxane oligomer may include at least one selected from cyclodimethylsiloxane, dimethyldimethoxysilane, and methyltrimethoxysilane. The binder is included in an amount of 17 to 20 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The binder made of the siloxane-based material of the present invention has a molecular weight of about 2500 to 5000, which is significantly lower than that of conventional photoacrylic polymers having a molecular weight of about 5000 to 10000. Therefore, since the dissolution rate of the siloxane-based binder itself is high, the UV exposure time can be shortened.

4, the siloxane-based binder has a hydroxyl group at its end, and the acrylic binder has a carboxyl group at its end. When the photosensitive resin is hydrogen-bonded to the photosensitive agent, the siloxane-based binder has a hydroxy- The carboxyl group is hydrogen bonded. Generally, since the hydroxy group is higher than the carboxyl group, the bond strength between the siloxane-based binder and the photosensitizer is remarkably excellent. Thus, when the siloxane-based organic material is exposed to UV light, the solubility contrast with the unexposed portion becomes large because the exposed portion has strong bonding force. Therefore, high sensitivity of the siloxane-based organic material can be realized.

In addition, since the siloxane-based material has a high heat resistance, the content of diazonaphthoquinone (DNQ) as a photosensitive agent can be reduced, thereby further improving the sensitivity and maintaining the residual film ratio after exposure.

The photosensitive agent may include the diazonaphthoquinone described above, and is contained in an amount of 5 to 8 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The solvent is selected from the group consisting of methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, dimethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol ethyl methyl acetate, And may be any one selected from the group consisting of chloroform, methyl ether acetate, ethyl-3-ethoxypropionate, ethyl cellosolve acetate, and butyl acetate. The solvent is contained in an amount of 70 to 75 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The additive includes materials having a hydrophilic and thermal sensitive functional group, for example, a tetrafluoroethylene or a vinylidene fluoride monomer that is hydrogen-substituted with a carboxyl group or a hydroxy group can do. The hydrophilic property of the additive can improve the moisture permeability of the siloxane-based organic material, and the thermosensitive functional group can improve the degree of curing. Therefore, it is possible to improve the chemical resistance according to the outgassing from the organic materials which are weak to heat inside the organic electroluminescent device.

Further, the additive includes a cross-linking agent such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, Trimethylol propane triacrylate, trimethylol propane triacrylate, ethoxylated trimethylol propane triacrylate, trimethylol propane trimethacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. .

Further, the additive includes a surfactant for improving the coating stability of the siloxane-based organic material, and for example, a polyether-dimethyl polysiloxane copolymer can be used. Such additives are included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total siloxane-based organic material.

The siloxane-based organic material of the present invention has high sensitivity and high reliability, and is used simultaneously in the overcoat layer and the bank layer of the organic electroluminescent device, thereby improving the reliability of the product and reducing the manufacturing cost.

Hereinafter, the siloxane-based organic material of the present invention will be described in detail in the following experimental examples. However, the following experimental examples are merely illustrative of the present invention, and the present invention is not limited to the following experimental examples.

Experimental Example

20 parts by weight of cyclodimethylsiloxane, 75 parts by weight of methyl ethyl ketone, 2 parts by weight of diazonaphthoquinone, 1 part by weight of tetrafluoroethylene hydrogen substituted with a hydroxy group, 1 part by weight of ethylene glycol diacrylate, -Dimethylpolysiloxane copolymer was prepared and then formed to a thickness of 2 탆 on a glass substrate. Then, a mask for forming holes having a size of 6 x 9 mu m was used, and holes were formed by changing the exposure energy to 50, 55, 60, 65, 70, and 75 mJ.

The hole size of the formed siloxane organic material was measured according to the above experimental example, and the shape of the hole on the surface was photographed and shown in FIG.

Referring to FIG. 5, it can be seen that when the exposure energy is 55 mJ, the hole size is approximately equal to the designed size of 6 × 9 μm. That is, in the case of the conventional photo-acryl, the siloxane-based organic material of the present invention can be lowered to about 40% by about 55 mJ, unlike the case where the exposure energy is about 140 to 180 mJ in order to form holes having a size of 6 × 9 μm.

The siloxane organic material of the present invention and the conventional organic photoacid generator of the present invention were found to have a siloxane organic content of about 60% as compared to the photoacrylic material.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

110: substrate 115: gate electrode
120: gate insulating film 125: semiconductor layer
130a and 130b: source and drain electrodes
135: Color filter layer 140: Overcoat layer
150: first electrode 155: bank layer
160: light emitting layer 170: second electrode

Claims (10)

A substrate on which a thin film transistor is formed;
An overcoat layer covering the thin film transistor on the substrate;
A first electrode located on the overcoat layer and connected to the thin film transistor;
A bank layer that exposes a portion of the first electrode and that covers the overcoat layer;
A light emitting layer disposed on the first electrode; And
And a second electrode located on the light emitting layer and facing the first electrode,
Wherein the overcoat layer and the bank layer comprise a siloxane-based organic material including a binder, a photosensitizer, a solvent, and an additive.
The method according to claim 1,
Wherein the overcoat layer and the bank layer are made of the same material.
delete The method according to claim 1,
Wherein the binder is a siloxane oligomer comprising at least one selected from the group consisting of cyclodimethylsiloxane, dimethyldimethoxysilane, and methyltrimethoxysilane.
The method according to claim 1,
Wherein the binder is contained in an amount of 17 to 20 parts by weight based on 100 parts by weight of the total siloxane-based organic material.
The method according to claim 1,
Wherein the additive comprises a tetrafluoroethylene or vinylidene fluoride monomer hydrogen-substituted with a carboxyl group or a hydroxy group.
The method according to claim 6,
Wherein the additive is included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the total siloxane-based organic material.
The method according to claim 1,
Wherein the additive comprises a crosslinking agent and a surfactant.
The method according to claim 1,
And a color filter is disposed between the first electrode and the substrate.
The method according to claim 1,
Wherein the organic electroluminescent device is a back light emitting structure in which light emitted from the light emitting layer is emitted to the substrate.

Images