KR100683675B1 - Organic light emitting device - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic light emitting device that can simplify the structure, improve productivity, and prevent the diffusion of mobile charge sources from a substrate. To this end, the present invention is an organic light emitting transistor having a semiconductor layer having a light emitting layer and a gate electrode interposed between a pair of electrodes facing each other, and connected to a gate electrode of the organic light emitting transistor, an upper electrode, a lower electrode, and An organic light emitting device is provided, comprising at least one MIM device having at least two insulating layers interposed therebetween.

Description

Organic light emitting device

1 is an equivalent circuit diagram of an organic light emitting diode according to an embodiment of the present disclosure;

2 is a plan view illustrating a layout of an organic light emitting diode according to FIG. 1;

3 is a cross-sectional view taken along line II of FIG. 2;

<Brief description of the main parts of the drawing>

10: substrate 11: first metal layer

12: second metal layer 13: insulating layer

13a: first insulating layer 13b: second insulating layer

14: third metal layer 15: fourth metal layer

16: fifth metal layer 17: pixel electrode

22 planarization film 24 semiconductor layer

27: gate electrode 28: organic light emitting layer

29: counter electrode

MIM: MIM element OLET: organic light emitting transistor

Cs: storage capacitor CT: contact

The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device using a metal insulator metal (MIM) device as a switching device.

A flat panel display device such as a liquid crystal display device, an organic electroluminescent device, or an inorganic electroluminescent device has a passive matrix passive matrix type and an active matrix active matrix type AM depending on the driving method thereof. )

In the passive matrix type, the anode and the cathode are simply arranged in columns and rows, respectively, so that the cathode is supplied with a scanning signal from a row driving circuit, and only one row of the plurality of rows is selected. In addition, a data signal is input to each pixel in the column driving circuit.

On the other hand, the active matrix type is a display device for realizing a video by controlling a signal input for each pixel by using a thin film transistor (hereinafter referred to as "TFT") It is used a lot as.

On the other hand, the active matrix type is a display device for realizing a video by controlling a signal input for each pixel by using a thin film transistor (hereinafter referred to as "TFT") It is used a lot as.

As described above, TFTs of an active matrix flat panel display have a source / drain region doped with a high concentration of impurities and a semiconductor active layer having a channel region formed between the source / drain regions and insulated from the semiconductor active layer. And a gate electrode positioned in an area corresponding to the source electrode and a source / drain electrode in contact with the source / drain region, respectively.

The semiconductor active layer is widely used as amorphous silicon or polycrystalline silicon, but the amorphous silicon has the advantage of being capable of low temperature deposition, but the electrical properties and reliability are deteriorated, and the large area of the display device is difficult. I use it. Polycrystalline silicon has a high current mobility of tens to hundreds of cm 2 /V.s, and has a high frequency operation characteristic and a low leakage current value, making it suitable for use in high-definition and large-area flat panel display devices.

By the way, when manufacturing a semiconductor active layer from polycrystalline silicon, the crystallization process which crystallizes amorphous silicon to polycrystalline silicon is needed, and this crystallization has a high temperature process of 300 degreeC or more normally.

On the other hand, modern flat panel display devices require very fast operation speed and uniformity of image quality for processing a moving image.

In particular, in the case of the organic light emitting device, a circuit having higher characteristics than that of a conventional liquid crystal display device must be implemented in order to process moving images of clean image quality. That is, in the case of the organic EL device, in addition to the switching device for switching the pixels, a driving device for the operation of the EL diode, which is the driving unit, must be separately provided. In addition, the TFT may further include a plurality of TFTs for use as various compensation circuits. . In addition, these capacitors require high capacitor capacities and a large number.

In the organic electroluminescent device as described above, a front light emitting type is developed to implement a light emitting part on an upper part of a layer on which a circuit is implemented, and to implement an image in a direction opposite to the layer on which a circuit is implemented to implement a complex circuit in each pixel. However, even at this time, there is a problem that the process is complicated due to the complicated configuration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an organic light emitting device which can simplify the structure, improve productivity, and prevent the diffusion of a mobile charge source from a substrate.

In order to achieve the above technical problem, the present invention,

An organic light emitting transistor having a semiconductor layer having a light emitting layer and a gate electrode interposed between a pair of electrodes facing each other; And

And at least one MIM device connected to a gate electrode of the organic light emitting transistor and having an upper electrode, a lower electrode, and at least two insulating layers interposed therebetween. .

One of the upper and lower electrodes of the MIM device and the gate electrode may include a contact portion connected to each other.

The contact part may be formed of a conductive material interposed between any one of an upper electrode and a lower electrode of the MIM device and the gate electrode.

The contact part may be formed of the same material as an electrode that is not connected to the gate electrode among the upper and lower electrodes of the MIM device.

The organic light emitting transistor,

Pixel electrodes;

An opposite electrode facing the pixel electrode;

A semiconductor layer interposed between the pixel electrode and the counter electrode and having a channel facing the pixel electrode from the pixel electrode and a gate electrode located in the channel; And

And a light emitting layer interposed between the semiconductor layer and the counter electrode.

The semiconductor layer includes a first semiconductor layer and a second semiconductor layer, and the gate electrode is interposed between the first semiconductor layer and the second semiconductor layer in the form of a plurality of grid electrodes, one end of which is formed in the MIM device. It may be connected.

The pixel electrode may be formed of the same material as any one of an upper electrode and a lower electrode of the MIM device.

The display device may further include a storage capacitor connected to the gate electrode of the organic light emitting transistor.

At least one electrode of the storage capacitor may be provided on the same layer as at least one of an upper electrode and a lower electrode of the MIM device.

One electrode of the storage capacitor may be connected to any one of an upper electrode and a lower electrode of the MIM device.

The insulating layer of the storage capacitor may be provided in at least two layers.

At least one of the insulating layers of the storage capacitor may include silicon nitride.

The insulating layer of the storage capacitor may be provided to extend from the insulating layer of the MIM device.

One of the electrodes of the storage capacitor and the gate electrode may include a contact portion connected to each other.

The contact part may be formed of a conductive material interposed between any one of the electrodes of the storage capacitor and the gate electrode.

At least one insulating layer of the insulating layers of the MIM device may include silicon nitride.

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

1 illustrates an equivalent circuit diagram of an organic light emitting diode according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the organic light emitting diode includes an organic light emitting transistor (OLET), a metal-insulator-metal (MIM) element, and a storage capacitor (Cs).

The organic light emitting transistor OLED is a three-electrode light emitter having a source, a drain, and a gate electrode. The source electrode S is connected to a high driving power source ELVDD having an anode function, and the drain electrode D is a cathode. It is connected to a functioning low drive power supply (ELVSS). The light emission is controlled by the signal by the gate electrode G.

The MIM device MIM functions as a switching device of the organic light emitting transistor OLED, and is connected to the scan line SCAN and the gate electrode G of the organic light emitting transistor OLED, respectively, and according to a scan signal, the gate electrode. Turn (G) ON / OFF.

The MIM element MIM may be equivalently substituted with a parallel connection circuit of a predetermined resistance component and a predetermined capacitor component, which exhibit electrical same characteristics. According to a preferred embodiment of the present invention, the MIM device MIM may have two MIM devices, a first MIM device MIM1 and a second MIM device MIM2, connected in series. It is not limited.

The first MIM element MIM1 includes a first capacitor component C _MIM1 and a first resistance component R _MIM1 connected in parallel with each other, and the second MIM element MIM2 includes a second capacitor component C _MIM2 connected in parallel with each other. It is provided with the 2nd resistance component R _MIM2 .

One end of the first capacitor component C _MIM1 and the first resistance component R _MIM1 is connected to the scan line, and the other end thereof has one end of the second capacitor component C _MIM2 and the second resistance component R _MIM2 . Are connected in common. The other ends of the second capacitor component C _MIM2 and the second resistance component R _MIM2 are connected to the gate electrode G of the organic light emitting transistor OLED.

The storage capacitor Cs is connected to the data line Data and the organic light emitting transistor OLED to store a data signal input to the gate electrode G of the organic light emitting transistor OLED for one frame.

FIG. 2 is a layout of an organic light emitting device for implementing the circuit as described above, and FIG. 3 is a cross-sectional view taken along line II of FIG. 2.

First, as shown in FIG. 3, the first metal layer 11 and the second metal layer 12 having a predetermined pattern are formed on the substrate 10. The first metal layer 11 is integrally connected to the scan line SCAN. The first metal layer 11 and the second metal layer 12 may be formed of the same material, and may be formed of a metal material such as aluminum, silver, and magnesium, but are not necessarily limited thereto. Materials may be used, and conductive oxides, conductive polymers, and the like may also be used.

An insulating layer 13 is formed to cover the first metal layer 11 and the second metal layer 12, and the third metal layer 14 and the fourth metal of a predetermined pattern are formed on the insulating layer 13. Layer 15 is formed.

The insulating layer 13 may be formed of at least two layers to prevent diffusion of the mobile charge source from the substrate 10.

According to an exemplary embodiment of the present invention, the insulating layer 13 may be provided with a double insulating layer of the first insulating layer 13a and the second insulating layer 13b.

The first insulating layer 13a and the second insulating layer 13b may be formed of an inorganic material such as silicon oxide or silicon nitride, or may be formed of an insulating organic material. At this time, it is preferable that at least one of the first insulating layer 13a and the second insulating layer 13b be formed of silicon nitride having a denser film quality.

As shown in FIG. 2, the fourth metal layer 15 is integrally connected to the data line DATA. In addition, the third metal layer 14 and the fourth metal layer 15 may be formed of the same material. It may be formed of the same material as the first metal layer 11 and the second metal layer 12.

However, as described later, when formed of the same material as the pixel electrode 17, it may be formed of a precious metal such as Au and Pt having a high work function, or may be formed of a conductive metal oxide.

A first MIM device MIM1 is formed by the first metal layer 11, the insulating layer 13, and the third metal layer 14 connected to the scan line SCAN. That is, the first metal layer 11 extending from the scan line SCAN becomes a lower electrode of the first MIM element MIM1 and overlaps the first metal layer 11 with the insulating layer 13 therebetween. A portion of the third metal layer 14 becomes an upper electrode of the first MIM device MIM1 to form the first MIM device MIM1.

The second MIM element MIM2 is formed by the portion of the second metal layer 12 extending below the third metal layer 14, the insulating layer 13, and the third metal layer 14. . That is, the portion of the second metal layer 12 extending below the third metal layer 14 becomes the lower electrode of the second MIM element MIM2, and the second metal layer is interposed with the insulating layer 13 interposed therebetween. The portion of the third metal layer 14 superimposed on the portion 12 becomes the upper electrode of the second MIM element MIM2 to form the second MIM element MIM2.

These first MIM elements MIM1 and the second MIM elements MIM2 are connected in series by sharing the third metal layer 14 with the upper electrode thereof.

Meanwhile, as shown in FIG. 2, the remaining portion of the second metal layer 12 connected to the lower electrode of the second MIM element MIM2 is the fourth metal layer 15 connected to the data line DATA. The storage capacitor Cs is formed to face each other with the insulating layer 13 therebetween. The fourth metal layer 15 may be formed of the same material as the third metal layer 14, and thus may proceed in the same process as forming the third metal layer 14 of the MIM device MIM.

The present invention can be formed in the same process as the storage capacitor (Cs) by using the MIM element (MIM), which is a two-electrode element as a switching element, thereby reducing the number of masks and the number of processes.

In addition, the pixel electrode 17 having a predetermined pattern may be formed on the insulating layer 13. The pixel electrode 17 may be connected to a high driving power source ELVDD to function as an anode of the OLED.

The pixel electrode 17 may also be formed of the same material as that of the third metal layer 14. Accordingly, the pixel electrode 17 may be processed in the same process as the formation of the third metal layer 14 of the MIM element MIM.

According to the present invention, since the formation of the MIM element MIM, the storage capacitor Cs, and the pixel electrode 17 can be performed in the same process, the number of masks and the number of processes can be reduced.

The planarization layer 22 is provided as an insulator on the MIM element MIM, the storage capacitor Cs, and the pixel electrode 17. The planarization layer 22 is formed of an organic material such as acryl, polyimide, and BCB. It may be formed as, in addition to the inorganic material, such as silicon nitride, silicon oxide.

A predetermined opening 22a is formed in the planarization film 22, and a semiconductor layer 24 is provided to cover the opening 22a. The organic light emitting layer 28 and the counter electrode are disposed on the semiconductor layer 24. Reference numeral 29 is provided sequentially to form an organic light emitting transistor (OLET).

The semiconductor layer 24 forms a channel in the direction of the pixel electrode 17 and the counter electrode 29. In this channel, the gate electrode 27 is present in the form of a grid electrode as shown in FIG. do.

The semiconductor layer 24 has a static induction transistor (SIT) structure in which the pixel electrode 17 and the counter electrode 29 are the source electrode and the drain electrode, respectively. The semiconductor layer 24 has the pixel electrode 17. ) And the channel is basically formed in the direction of the counter electrode 29, so that if a voltage is not applied to the gate electrode 27, a constant current flows in the direction of the counter electrode 29 from the pixel electrode 17. .

However, when a constant voltage is applied to the gate electrode 27, a depletion area extends from the gate electrode 27 to reduce the width of the channel through which the current flows, resulting in a gap between the pixel electrode 17 and the counter electrode 29. The current flowing through it will be reduced. When the voltage applied to the gate electrode 27 exceeds a predetermined threshold voltage, depletion regions extending from adjacent grid electrodes meet each other, and the channel between the pixel electrode 17 and the counter electrode 29 is disconnected. No more current will flow.

To this end, in the semiconductor layer 24 of the present invention, the first semiconductor layer 25 and the second semiconductor layer 26 are sequentially formed on the planarization film 22, and the gate electrode 27 is interposed therebetween. do. The gate electrode 27 may be formed of a conductive metal such as aluminum, but is not limited thereto. Various kinds of metals, conductive oxides, conductive polymers, and the like may be used. It is preferable that the first semiconductor layer 25 and the second semiconductor layer 26 having the gate electrode 27 interposed therebetween be formed of the same kind of material.

As shown in FIGS. 2 and 3, the gate electrode 27 is connected to the MIM device MIM and the storage capacitor Cs through the contact portion CT.

According to a preferred embodiment of the present invention, the contact portion CT is a fifth metal layer interposed between the second metal layer 12 and the gate electrode 27, which is a lower electrode of the second MIM element MIM2. 16 may be provided.

The fifth metal layer 16 is formed on the insulating layer 13, and forms contact holes in the insulating layer 13 to contact the second metal layer 12.

The fifth metal layer 16 may be formed of the same metal material as the third metal layer 14, but is not limited thereto and may be formed of various conductive materials in addition to the metal material.

An organic light emitting layer 28 is provided on the semiconductor layer 24. The organic light emitting layer 28 may be formed of the same material as that of the organic light emitting diode (OLED).

For example, in the case of small molecules, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer ( Electron Injection Layer (EIL) and the like may be formed by stacking a single or complex structure, and the usable organic materials may be copper phthalocyanine (CuPc), N, N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1-yl) -N, N'-diphenyl-benzidine: NPB), tris-8-hydroxyquinoline aluminum It can be applied in various ways, including (Alq3). These can be formed by the method of vacuum deposition.

In the case of the polymer, it may have a structure which is usually provided as a hole transport layer (HTL) and a light emitting layer (EML), wherein PEDOT is used as the hole transport layer, and poly-phenylene vinylene (PPV) and polyfluorene (PV) as the light emitting layer. Polymer organic materials such as polyfluorene) may be used and may be formed by screen printing or inkjet printing.

A counter electrode 29 may be formed on the organic light emitting layer 28 to cover all the pixels, and a low driving power source ELVSS is connected to the counter electrode 29.

The organic light emitting transistor has a high driving speed because the channel length between the source and the drain is very short, and can be driven at a low voltage.

In addition, in the case of the organic light emitting device having the above structure, the number of processes for forming the MIM device (MIM), the storage capacitor (Cs), and the pixel electrode, which are switching devices, can be reduced, thereby further improving productivity and yield. Will be.

As described above, according to the organic light emitting diode according to the present invention, the following effects can be obtained.

First, since the MIM element serving as the switching element, the storage capacitor and the pixel electrode can be formed in the same process, the number of masks and the number of processes can be reduced.                     

Second, the double insulating layer can prevent the diffusion of the mobile charge source from the substrate.

As described above, the optimum embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (16)

An organic light emitting transistor having a semiconductor layer having a light emitting layer and a gate electrode interposed between a pair of electrodes facing each other; And And a MIM device connected to the gate electrode of the organic light emitting transistor, the MIM device having an upper layer electrode, a lower electrode, and two insulating layers interposed therebetween. The method of claim 1, The organic light emitting device of claim 1, further comprising a contact portion in which one of an upper layer electrode and a lower layer electrode of the MIM element is connected to the gate electrode. The method of claim 2, And the contact portion is made of a conductive material interposed between any one of an upper electrode and a lower electrode of the MIM element and the gate electrode. The method of claim 2, And the contact portion is made of the same material as an electrode which is not connected to the gate electrode among the upper and lower electrodes of the MIM device. The method of claim 1, The organic light emitting transistor, Pixel electrodes; An opposite electrode facing the pixel electrode; A semiconductor layer interposed between the pixel electrode and the counter electrode and having a channel facing the pixel electrode from the pixel electrode and a gate electrode located in the channel; And And a light emitting layer interposed between the semiconductor layer and the counter electrode. The method of claim 5, The semiconductor layer includes a first semiconductor layer, and a second semiconductor layer, And the gate electrode is interposed between the first semiconductor layer and the second semiconductor layer in the form of a plurality of grid electrodes, one end of which is connected to the MIM device. The method of claim 5, And the pixel electrode is made of the same material as any one of an upper electrode and a lower electrode of the MIM device. The method of claim 1, And a storage capacitor connected to the gate electrode of the organic light emitting transistor. The method of claim 8, At least one electrode of the storage capacitor is provided on the same layer as at least one of the upper electrode and the lower electrode of the MIM device. The method of claim 8, Any one electrode of the storage capacitor is connected to any one of the upper electrode and the lower electrode of the MIM device. The method of claim 8, The insulating layer of the storage capacitor is an organic light emitting device, characterized in that provided in two layers. The method of claim 11, And at least one of the insulating layers of the storage capacitor includes silicon nitride. The method of claim 11, And an insulating layer of the storage capacitor is formed to extend from the insulating layer of the MIM device. The method of claim 8, An organic light emitting device according to claim 1, wherein the organic light emitting device comprises a contact portion in which any one of the electrodes of the storage capacitor is connected to the gate electrode. The method of claim 14, The contact unit is formed of a conductive material interposed between any one of the electrodes of the storage capacitor and the gate electrode. The method of claim 1, One of the insulating layers of the MIM device comprises silicon nitride;

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