KR20070073096A - Display device and manufacturing method of the same - Google Patents

Abstract

A display device and a manufacturing method thereof are provided to uniformly deposit a hole transport layer on a substrate by preventing chemical vapor from being generated during the deposition process. A display device includes an insulation substrate(110), a TFT(Thin Film Transistor)(120), a first electrode(133), a light emitting layer(152), and a second electrode(161). The TFT is formed on the insulation substrate. The first electrode is connected to the TFT. The light emitting layer is formed on the first electrode and contains an electron transport blue light emitting material and a hole transport blue light emitting material. The second electrode is formed on a white light emitting layer. The white light emitting layer is made by co-depositing the electron transport blue light emitting material with the hole transport blue light emitting material.

Description

DISPLAY DEVICE AND MANUFACTURING METHOD OF THE SAME}

1 is an equivalent circuit diagram of a pixel of a display device according to an exemplary embodiment of the present invention.

2 is a cross-sectional view of a display device according to an exemplary embodiment of the present invention.

3A and 3B are graphs illustrating light emission characteristics of a white light emitting layer according to an embodiment of the present invention.

4A through 4C are cross-sectional views sequentially illustrating a method of manufacturing a display device according to an exemplary embodiment of the present invention.

Explanation of Signs of Major Parts of Drawings

110: insulating substrate 120: thin film transistor

132: protective film 133: pixel electrode

141: partition 150: organic layer

151: hole transport layer 152: white light emitting layer

153: electron transport layer 161: common electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a method of manufacturing the same, and more particularly, to a display device including a hole transport blue light emitting material and an electron transport blue light emitting material, and a method of manufacturing the white light emitting layer.

Among flat panel displays, organic light emitting diodes (OLEDs) have recently been in the spotlight due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response. OLEDs are classified into a passive matrix and an active matrix according to the driving method. The passive type has a simple manufacturing process, but the power consumption increases rapidly as the display area and resolution increase. Therefore, the passive type is mainly applied to small displays. Active type, on the other hand, has a complex manufacturing process but has the advantage of realizing a large screen and high resolution.

An OLED includes various organic layers, such as a hole transport layer, a light emitting layer, and an electron transport layer, for example, These organic layers are formed between the anode electrode which supplies a hole, and the cathode electrode which supplies an electron.

The organic layer is formed by thermal evaporation by heating the source, which requires a large number of sources, and thus, the organic layer manufacturing process is complicated.

Accordingly, an object of the present invention is to provide a display device including an organic layer having a simple manufacturing process.

Another object of the present invention is to provide a method of manufacturing a display device including an organic layer having a simple manufacturing process.

The object of the present invention is an insulating substrate; A thin film transistor formed on the insulating substrate; A first electrode connected to the thin film transistor; A white light emitting layer on the first electrode and including an electron transporting blue light emitting material and a hole transporting blue light emitting material; A display device including a second electrode formed on the white light emitting layer is provided.

The white light emitting layer is preferably formed by co-deposition (codeposition) of the electron transport blue light emitting material and the hole transport blue light emitting material.

The white light emitting layer is preferably formed by a thermal evaporation method.

The electron transport blue light emitting material may include an oxadiazole group, and the hole transport blue light emitting material may include an amine group.

The electron transport blue light emitting material is represented by the following Chemical Formula 1, and the hole transport blue light emitting material is preferably represented by the following Chemical Formula 2.

[Formula 1]

[Formula 2]

A hole transport layer is disposed between the first electrode and the white light emitting layer, the hole transport layer further comprising the hole transport blue light emitting material.

It is preferred that the electron transport layer further comprises an electron transport blue light emitting material positioned between the white light emitting layer and the second electrode.

It is preferable to further include a color filter positioned between the insulating substrate and the first electrode.

Another object of the present invention is to form a thin film transistor on an insulating substrate; Forming a first electrode connected to the thin film transistor; Simultaneously depositing an electron transport blue light emitting material and a hole transport blue light emitting material on the first electrode to form a white light emitting layer; The manufacturing method of the display device includes forming a second electrode on the white light emitting layer.

The white light emitting layer is preferably formed by a thermal evaporation method.

Forming a hole transport layer made of the hole transport blue light emitting material after the formation of the first electrode; After forming the white light emitting layer, it is preferable to further include forming an electron transport layer made of the electron transport blue light emitting material.

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

In the description, "on" or "on" means that no other layer is interposed between the two layers (membrane), and "just above" indicates that the two layers (membrane) are in contact with each other.

1 is an equivalent circuit diagram of a pixel in a display device according to an exemplary embodiment of the present invention.

A plurality of signal lines are provided in one pixel. The signal line includes a gate line for transmitting a scan signal, a data line for transmitting a data signal, and a driving voltage line for transmitting a driving voltage. The data line and the driving voltage line are adjacent to each other and disposed side by side, and the gate line extends perpendicular to the data line and the driving voltage line.

Each pixel includes an organic light emitting element LD, a switching thin film transistor Tsw, a driving thin film transistor Tdr, and a capacitor C.

The driving thin film transistor Tdr has a control terminal, an input terminal, and an output terminal. The control terminal is connected to the switching thin film transistor Tsw, the input terminal is connected to a driving voltage line, and the output terminal is an organic light emitting diode ( LD).

The organic light emitting element LD has an anode connected to the output terminal of the driving thin film transistor Tdr and a cathode connected to the common voltage Vcom. The organic light emitting element LD displays an image by emitting light having a different intensity according to the output current of the driving thin film transistor Tdr. The current of the driving thin film transistor Tdr varies in magnitude depending on the voltage applied between the control terminal and the output terminal.

The switching thin film transistor Tsw also has a control terminal, an input terminal and an output terminal, the control terminal is connected to the gate line, the input terminal is connected to the data line, and the output terminal of the driving thin film transistor Tdr. It is connected to the control terminal. The switching thin film transistor Tsw transfers a data signal applied to the data line to the driving thin film transistor Tdr according to a scan signal applied to the gate line.

The capacitor C is connected between the control terminal and the input terminal of the driving thin film transistor Tdr. The capacitor C charges and maintains a data signal input to the control terminal of the driving thin film transistor Tdr.

A display device according to an embodiment of the present invention will be described with reference to FIG. 2.

The display device 100 includes a thin film transistor 120 formed on the insulating substrate 110, a pixel electrode 133 electrically connected to the thin film transistor 120, and an organic layer formed on the pixel electrode 133. And 150.

In the figure, although the thin film transistor 120 using amorphous silicon is illustrated, a thin film transistor using polysilicon may be used.

Looking at the display device 100 in detail as follows.

The gate electrode 121 is formed on an insulating substrate 110 made of an insulating material such as glass, quartz, ceramic, or plastic.

A gate insulating layer 122 made of silicon nitride (SiNx) or the like is formed on the insulating substrate 110 and the gate electrode 121. The semiconductor layer 123 made of amorphous silicon and the ohmic contact layer 124 made of n + hydrogenated amorphous silicon heavily doped with n-type impurities are sequentially formed on the gate insulating layer 122 where the gate electrode 121 is disposed. Here, the ohmic contact layer 124 is separated from both sides with respect to the gate electrode 121.

The source electrode 125 and the drain electrode 126 are formed on the ohmic contact layer 124 and the gate insulating layer 122. The source electrode 125 and the drain electrode 126 are separated around the gate electrode 121.

The color filter 131 is formed between adjacent thin film transistors Tdr. The color filter 131 includes three sublayers 131a, 131b, and 131c of different colors. The white light generated by the organic layer 150 is given a color while passing through the color filter 131 and is emitted to the outside through the insulating substrate 110.

The passivation layer 132 is formed on the source electrode 125, the drain electrode 126, and the semiconductor layer 123 not covered by the source electrode 125 and the drain electrode 126. The passivation layer 132 may be formed of silicon nitride (SiNx) and / or an organic layer. In the passivation layer 132, a contact hole 127 exposing the drain electrode 126 is formed.

The pixel electrode 133 is formed on the passivation layer 132. The pixel electrode 133 is also called an anode and supplies holes to the organic emission layer 152. The pixel electrode 133 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), and is formed by a sputtering method. The pixel electrode 133 may be patterned into a substantially rectangular shape in plan view.

A partition 141 is formed between each pixel electrode 133. The partition wall 141 defines the pixel area by separating the pixel electrodes 133 and is formed on the thin film transistor 120 and the contact hole 127. The partition wall 141 also serves to prevent the source electrode 125 and the drain electrode 126 of the thin film transistor 120 from being short-circuited with the common electrode 161. The partition wall 141 may be formed of a photoresist having heat resistance and solvent resistance, such as an acrylic resin and a polyimide resin, or an inorganic material such as SiO 2 or TiO 2, and may have a two-layer structure of an organic layer and an inorganic layer.

The organic layer 150 is formed on the pixel electrode 133. The organic layer 150 includes a hole transport layer 151, a white light emitting layer 152, and an electron transport layer 153. Each of the organic layers 150 is formed on the entire surface of the insulating substrate 110 and is formed by a thermal evaporation method. The thickness of each layer constituting the organic layer 150 is about 80 nm.

The hole transport layer 151 is made of a hole transport blue light emitting material. The hole transport blue light emitting material may include a functional group that attracts electrons, for example, an oxadiazole group. The hole transport blue light emitting material may be the first compound represented by Chemical Formula 1.

The electron transport layer 153 is made of an electron transport blue light emitting material. The electron transport blue light emitting material may include a functional group that emits electrons, for example, an amine group. The electron transport blue light emitting material may be a second compound represented by Chemical Formula 2.

The white light emitting layer 152 positioned between the hole transport layer 151 and the electron transport layer 153 includes both a hole transport blue light emitting material and an electron transport blue light emitting material. The white light emitting layer 152 may be formed by co-deposition (codeposition) of the electron transport blue light emitting material and the electron transport blue light emitting material. The white light emitting layer 152 is formed over the entire surface of the insulating substrate 110, but mainly emits light only in the partition wall 141 in which the pixel electrode 133 is located. The white light emitted from the white light emitting layer 152 is emitted to the outside through the hole transport layer 151, the passivation layer 132, the color filter 131, and the insulating substrate 110, and is given color through the color filter 131. do.

The common electrode 161 is formed on the charge transfer composite layer 154, and the common electrode 161 applies the same common voltage to all the pixels. The common electrode 161 is formed over the entire insulating substrate 110 and may be a double layer of LiF / Al.

Holes transferred from the pixel electrode 133 and electrons transferred from the common electrode 161 are combined in the white light emitting layer 153 to form excitons, and then generate light in the process of deactivating excitons.

Although not shown, the display device 100 may further include a protective film for protecting the common electrode 161, and an encapsulation member for preventing moisture and air from penetrating into the organic layer 150. The sealing member may be formed of a sealing resin and a sealing can. In addition, a hole injection layer may be further included between the pixel electrode 133 and the hole transport layer 151.

Hereinafter, the light emission characteristics of the white light emitting layer will be described with reference to FIGS. 3A and 3B.

FIG. 3A shows a first compound (hole transport blue light emitting material) and a second compound (electron transport blue light emitting material) formed between the first electrode ITO and the second electrode Li-Al, and then between both electrodes. The characteristics of the light emitted while measuring various voltages are measured.

Since the first compound and the second compound form separate layers, the light emitted is generated at the interface between the first compound layer and the second compound layer.

The simplified system of FIG. 3A is represented by a first electrode (ITO) / first compound (400 nm thickness) / second compound (200 nm thickness) / second electrode (Li-Al).

The system of FIG. 3B differs only in the thickness of the compound in the system in FIG. 3A and is represented by a first electrode (ITO) / first compound (200 nm thickness) / second compound (400 nm thickness) / second electrode (Li-Al). .

3A to 3B, it can be seen that the light emitted emits light in all of the visible light region 400 nm to 700 nm regardless of the thickness of the compound layer. In other words, white light is supplied by emitting light in all visible light. Even when the voltage applied to both electrodes changes, the characteristic of emitting light in the entire visible light region does not change.

As described, the white light emitted in the experiment is formed at the interface between the first compound layer and the second compound layer. On the other hand, in this embodiment, since the first compound and the second compound are co-deposited, the interface between the first compound and the second compound is greatly increased, so that the white light emission efficiency of the white light emitting layer 152 is very excellent.

Hereinafter, a method of manufacturing a display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 4A to 4C.

FIG. 4A illustrates a process of forming the hole transport layer 151 by the thermal evaporation method on the deposition target plate 101 formed up to the pixel electrode 133.

The deposition target plate 101 is disposed such that the pixel electrode 133 faces downward, and the first source 155 including the first compound (hole transport blue light emitting material) is disposed below the deposition target plate 101. The second source 156 containing the second compound (electron transport blue light emitting material) is located.

In the process of forming the hole transport layer 151, the first source 155 is heated to supply the first compound vapor to the deposition counter plate 101. The first compound vapor, which is in contact with the deposition counter plate 101, is cooled and solidified to form the hole transport layer 151. In this process, the second source 156 is not heated so that no second compound vapor is generated. In the process of forming the hole transport layer 151, the deposition counter plate 101 rotates in a self-centered manner for uniform deposition.

4B illustrates a process of forming the white light emitting layer 152 by the thermal evaporation method on the deposition target plate 101 on which the hole transport layer 151 is formed.

The deposition counter plate 101 is continuously disposed such that the pixel electrode 133 faces downward.

In the process of forming the white light emitting layer 152, both the first source 155 and the second source 156 are heated. As a result, the first compound vapor and the second compound vapor are supplied to the deposition counter plate 101. The first compound vapor and the second compound vapor which are in contact with the deposition counter plate 101 are solidified while being cooled to form the white light emitting layer 152. The formed white light emitting layer 152 has a very large area of the interface where the first compound and the second compound meet.

Next, as shown in FIG. 4C, the electron transport layer 153 is formed on the deposition target plate 101 on which the white light emitting layer 152 is formed by thermal evaporation.

The deposition counter plate 101 is continuously disposed such that the pixel electrode 133 faces downward.

In the process of forming the electron transport layer 153, the second source 156 is heated to supply the second compound vapor to the deposition counter plate 101. The second compound vapor, which is in contact with the deposition counterplate 101, is cooled and solidified to form the electron transport layer 153. In this process, the first source 155 is not heated so that the first compound vapor is not generated.

According to the present invention, the hole transport layer 151, the white light emitting layer 152, and the electron transport layer 153 may be formed by adjusting only the heating of the first source 155 and the second source 156. Simple. In addition, three layers can be manufactured using only two sources 155 and 156, which simplifies the manufacturing apparatus.

Finally, when the common electrode 161 is formed on the electron transport layer 153, the display device 100 shown in FIG. 2 is completed.

Although embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that the present embodiments may be modified without departing from the spirit or principles of the present invention. The scope of the present invention will be defined by the appended claims and their equivalents.

As described above, according to the present invention, a display device including an organic layer having a simple manufacturing process and a method of manufacturing the same are provided.

Claims (12)

An insulating substrate; A thin film transistor formed on the insulating substrate; A first electrode connected to the thin film transistor; A white light emitting layer on the first electrode and including an electron transporting blue light emitting material and a hole transporting blue light emitting material; And a second electrode formed on the white light emitting layer. The method of claim 1, And the white light emitting layer is formed by co-deposition of the electron transport blue light emitting material and the hole transport blue light emitting material. The method of claim 2, The white light emitting layer is formed by a thermal evaporation method. The method according to any one of claims 1 to 3, The electron transport blue light emitting material includes an oxadiazole group, and the hole transport blue light emitting material includes an amine group. The method of claim 4, wherein The electron transport blue light emitting material is represented by the following Chemical Formula 1, and the hole transport blue light emitting material is represented by the following Chemical Formula 2. [Formula 1]

[Formula 2]

The method according to any one of claims 1 to 3, And a hole transport layer between the first electrode and the white light emitting layer and formed of the hole transporting blue light emitting material. The method of claim 6, And an electron transport layer disposed between the white light emitting layer and the second electrode and formed of the electron transport blue light emitting material. The method of claim 1, And a color filter disposed between the insulating substrate and the first electrode. Forming a thin film transistor on the insulating substrate; Forming a first electrode connected to the thin film transistor; Simultaneously depositing an electron transport blue light emitting material and a hole transport blue light emitting material on the first electrode to form a white light emitting layer; And forming a second electrode on the white light emitting layer. The method of claim 9, The white light emitting layer is formed by a thermal evaporation method. The method of claim 9 or 10, The electron transport blue light emitting material is represented by the following Formula 1, and the hole transport blue light emitting material is represented by the following formula (2). [Formula 1]

[Formula 2]

The method of claim 9 or 10, Forming a hole transport layer made of the hole transport blue light emitting material after the formation of the first electrode; And forming an electron transport layer made of the electron transport blue light emitting material after the white light emission layer is formed.

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