KR20180034856A - Organic Light Emitting Display Device - Google Patents

Abstract

According to an embodiment of the present invention, an organic light emitting display device comprises: a flexible substrate; a shielding layer on the flexible substrate; a plurality of thin film transistors including a gate electrode, a source electrode, a drain electrode, and a semiconductor layer on the flexible substrate; and an organic light emitting element on the plurality of thin film transistors. At least one of the plurality of thin film transistors has the gate electrode and the shielding layer on the same layer. Therefore, the performance of the organic light emitting display device can be improved.

Description

[0001] The present invention relates to an organic light emitting display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display including a thin film transistor having a shielding layer.

As the era of information age approaches, there is a rapid development of a display device field for visually displaying electrical information signals, and studies for developing performance such as thinning, lightening, and low power consumption for various display devices are continuing.

Typical display devices include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), an electro-wetting device Display device (EWD), and organic light emitting display device (OLED). Among them, the organic light emitting display device is a self light emitting display device, and unlike a liquid crystal display device, a separate light source is not required, so that it can be manufactured in a light and thin shape. In addition, the organic light emitting display device is expected to be a next-generation display with low power and high image quality because it is advantageous in terms of power consumption by low-voltage driving and has excellent color reproduction, response speed, viewing angle, and contrast ratio (CR) .

An organic light emitting diode (OLED) display device includes a light emitting layer (EML) formed of an organic material between two electrodes made of an anode and a cathode, a hole injected from the anode into the light emitting layer, ) Is injected from the cathode to the light emitting layer, the injected electrons and holes recombine with each other to form an exciton and generate light.

A host material and a dopant material are contained in the light emitting layer of the organic light emitting display device and light is emitted through interaction of the two materials. At this time, the host generates an exciton from electrons and holes and transfers energy to the dopant. A dopant is a dye organic material to which a small amount is added, and receives energy from a host and converts it into light.

2. Description of the Related Art Generally, an organic light emitting display device is driven by using a thin film transistor (Thin Film Transistor). The thin film transistor is an element including a gate electrode, a drain electrode and a source electrode. At this time, an electric signal transmitted from the outside is injected between the drain electrode and the source electrode, Layer, and the gate electrode acts as a switch or a valve.

[Prior Art Literature]

[Patent Literature]

One. [White organic light emitting device] (Patent Application No. 10-2007-0053472)

A recent organic light emitting display device can be applied to various product groups using a flexible substrate. However, the flexible substrate included in the organic light emitting display device may deteriorate the performance of the thin film transistor disposed on the top due to the charged charges generated in the substrate during long-term driving due to the unique characteristics thereof.

In addition, although the thin film transistor included in the organic light emitting display device is required to have various characteristics of the thin film transistor in accordance with the object, when the process or structure is changed in order to change the characteristics of the thin film transistor, There is a possibility that there will be a case in which a change occurs up to a certain level.

The inventors of the present invention have recognized the above-mentioned problems and have invented an organic light emitting display device including a thin film transistor of a new structure through various experiments.

The solutions according to the embodiments of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a shielding layer on the flexible substrate, a plurality of thin film transistors including a gate electrode, a source electrode, a drain electrode and a semiconductor layer on a flexible substrate, At least one of the organic light emitting element and the plurality of thin film transistors includes a thin film transistor in which the gate electrode and the shielding layer are the same layer.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a shielding layer on the flexible substrate, a plurality of thin film transistors on the flexible substrate, and an organic light emitting element on the plurality of thin film transistors, At least one thin film transistor of the thin film transistor has a gate electrode of the at least one thin film transistor in the same layer as the shielding layer so that a variation amount of the driving current (Ids) according to the gate voltage (Vgs) is minimized.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a plurality of shielding layers on a flexible substrate, a first thin film transistor and a second thin film transistor on a plurality of shielding layers, The first thin film transistor and the second thin film transistor each include a gate electrode, a semiconductor layer, a source electrode, and a drain electrode, and the gate electrode included in the first thin film transistor includes a semiconductor layer And the gate electrode included in the second thin film transistor is in the same layer as the shielding layer.

The details of other embodiments are included in the detailed description and drawings.

Since the organic light emitting display according to the embodiment of the present invention can prevent the semiconductor layer of the thin film transistor disposed on the top due to the electrified charge of the flexible substrate from being affected through the shielding layer, Can be provided.

The organic light emitting diode display according to the exemplary embodiment of the present invention may be fabricated by changing the process or structure of another type of thin film transistor through a minimized change of a common structure when a plurality of types of thin film transistors having various characteristics are disposed It is possible to provide a thin film transistor capable of minimizing the change of undesirable characteristics.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

The scope of the claims is not limited by the matters described in the contents of the invention, as the contents of the invention described in the problems, the solutions to the problems and the effects to be solved do not specify essential features of the claims.

1 is a schematic block diagram of an OLED display according to an embodiment of the present invention.
2 is a circuit diagram of a pixel included in an organic light emitting display according to an embodiment of the present invention.
3 is a cross-sectional view of a pixel included in an OLED display according to an exemplary embodiment of the present invention.
4 is a cross-sectional view of a first thin film transistor included in an OLED display according to an embodiment of the present invention.
5 is a cross-sectional view of a second thin film transistor included in an organic light emitting display according to an embodiment of the present invention.
6A and 6B are transfer curves showing characteristics of the first thin film transistor and the second thin film transistor included in the organic light emitting diode display according to the embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

FIG. 1 is a schematic block diagram of an organic light emitting diode display 100 according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 1, an OLED display 100 includes an image processor 110, a timing controller 120, a data driver 130, a gate driver 140, and a display panel 150.

The image processing unit 110 outputs a data enable signal DE together with a data signal DATA supplied from the outside. The image processing unit 110 may output at least one of a vertical synchronization signal, a horizontal synchronization signal, and a clock signal in addition to the data enable signal DE.

The timing controller 120 receives a data enable signal DE or a data signal DATA in addition to a drive signal including a vertical synchronization signal, a horizontal synchronization signal, and a clock signal from the image processing unit 110. The timing controller 120 generates a gate timing control signal GDC for controlling the operation timing of the gate driver 140 and a data timing control signal DDC for controlling the operation timing of the data driver 130 based on the drive signal. .

The data driver 130 samples and latches the data signal DATA supplied from the timing controller 120 in response to the data timing control signal DDC supplied from the timing controller 120 and converts the sampled data signal into a gamma reference voltage . The data driver 130 outputs the data signal DATA through the data lines DL1 to DLn.

The gate driver 140 outputs a gate signal while shifting the level of the gate voltage in response to the gate timing control signal GDC supplied from the timing controller 120. The gate driver 140 outputs the gate signal through the gate lines GL1 to GLm.

The display panel 150 displays an image while the pixel 160 emits light corresponding to the data signal DATA and the gate signal supplied from the data driver 130 and the gate driver 140.

2 is a circuit diagram of a pixel included in the organic light emitting diode display 200 according to the embodiment of the present invention.

2, the pixel included in the OLED display 200 includes a switching transistor 230, a driving transistor 240, a compensation circuit 250, and an organic light emitting diode 260.

The organic light emitting element 260 operates to emit light in accordance with the driving current transmitted by the driving transistor 240.

The switching transistor 260 performs a switching operation so that a data signal supplied through the data line 220 corresponding to the gate signal supplied through the gate line 210 is stored as a data voltage in a capacitor.

The driving transistor 240 operates so that the driving current flows between the high potential power supply line VDD and the low potential power supply line GND according to the data voltage stored in the capacitor. At this time, it is important that the driving transistor supply a constant driving current to the organic light emitting element 260.

The compensation circuit 250 is a circuit for compensating the threshold voltage of the driving transistor 240 and the compensation circuit 250 is composed of one or more thin film transistors and a capacitor. The configuration of the compensation circuit varies greatly according to the compensation method, and a detailed description thereof will be omitted.

Basically, the pixel of the organic light emitting display is composed of a 2T (Transistor) 1C (Capacitor) structure including a switching transistor 230, a driving transistor 240, a capacitor and an organic light emitting diode 260, If added, it may be variously configured as 3T1C, 4T2C, 5T2C, 6T2C, 7T2C, and the like.

3 is a cross-sectional view of a pixel included in the OLED display 300 according to the embodiment of the present invention.

Referring to FIG. 3, the OLED display 300 includes a substrate 310, a thin film transistor 320, and an organic light emitting diode 340.

The substrate 310 serves to support and protect the components of the organic light emitting diode display 300 disposed thereon. Recently, a plastic substrate such as a polyimide having a flexible characteristic is applied to various display devices.

On the substrate 310, a buffer layer 312 for preventing penetration of moisture, oxygen, and the like from the outside of the substrate 310 is disposed. The buffer layer 312 may be formed of a single layer or a plurality of layers of silicon oxide (SiOx) or silicon nitride (SiNx). However, the buffer layer 312 may be omitted depending on the structure and characteristics of the OLED display 300 have.

A shielding layer 314 may be disposed on the substrate 310 or between the buffer layer 312. The substrate 310 having a flexible characteristic using a material such as polyimide can affect the semiconductor layer 328 of the thin film transistor 320 disposed on the top due to the charged charges. In order to prevent this, a shielding layer 314 made of a metal may be disposed between the substrate 310 and the semiconductor layer 328 to minimize the influence of charges generated from the substrate 310.

At this time, the shielding layer 314 is formed of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), chrome (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium ), Or an alloy thereof, and may be composed of a single layer or multiple layers.

The shield layer 314 may be electrically connected to the source electrode 324 or may be used as various components. The detailed structure of the shield layer 314 will be described with reference to FIGS.

The thin film transistor 320 includes a gate electrode 322, a source electrode 324, a drain electrode 326, and a semiconductor layer 328.

The semiconductor layer 328 has a higher mobility than amorphous silicon or amorphous silicon and has low energy consumption and excellent reliability. The semiconductor layer 328 can be formed of polycrystalline silicon applicable to a driving transistor in a pixel, or excellent in mobility and uniformity Or an oxide semiconductor such as ZnO or IGZO (Indium-Gallium-Zinc Oxide). At this time, the semiconductor layer 328 may include a source region including a p-type or n-type impurity, a drain region and a channel between the two regions, and a low concentration doped region may be added between the source region and the drain region adjacent to the channel .

The gate insulating layer 331 is an insulating film composed of a single layer or a plurality of layers of silicon oxide (SiOx) or silicon nitride (SiNx), and is arranged such that a current flowing in the semiconductor layer 328 does not flow to the gate electrode 322. [

The gate electrode 322 serves as a switch or a valve of the thin film transistor 320 and may be formed of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), chrome (Cr) , Titanium (Ti), nickel (Ni), and neodymium (Nd), or alloys thereof, and may be composed of a single layer or multiple layers.

The source electrode 324 and the drain electrode 326 allow external electrical signals to be transmitted from the thin film transistor 320 to the organic light emitting diode 340. The source electrode 324 and the drain electrode 326 may be formed of a conductive metal such as copper, aluminum, molybdenum, chromium, gold, titanium, Nickel (Ni), and neodymium (Nd), or an alloy thereof, and may be composed of a single layer or multiple layers.

An interlayer insulating layer 333 can be disposed between the gate electrode 322 and the source electrode 324 and the drain electrode 326 in order to insulate the gate electrode 322 from the source electrode 324 and the drain electrode 326 have.

A passivation layer 335 composed of an inorganic insulating film such as silicon oxide (SiOx) or silicon nitride (SiNx) is disposed on the top of the thin film transistor 320 to prevent unnecessary electrical connection between the elements of the thin film transistor 320 Contamination or damage from the outside can be prevented.

And may be classified into an inverted staggered structure and a coplanar structure depending on the positions of the constituent elements of the thin film transistor 320. In the thin film transistor of the inverted staggered structure, the gate electrode is located on the opposite side of the source electrode and the drain electrode with respect to the semiconductor layer. 3, the thin film transistor 320 of the coplanar structure is positioned such that the gate electrode 322 is on the same side of the source electrode 324 and the drain electrode 326 with respect to the semiconductor layer 328. As shown in FIG.

Although the thin film transistor 320 is shown as a coplanar structure in FIG. 3, the thin film transistor may have a structure of inverted staggered structure.

The planarization layer 337 may be disposed on the upper portion of the thin film transistor 320 in order to protect the thin film transistor 320 and alleviate a step caused by the thin film transistor 320. [ At this time, the planarization layer 337 may be formed of an organic material such as polyimide or photo acryl.

The organic light emitting device 340 disposed on the planarizing layer 337 includes an anode 344, a light emitting portion 346, and a cathode 348.

The anode 344 may be disposed on the planarization layer 337. The anode 344 is an electrode serving to supply holes to the light emitting portion 346 and may be electrically connected to the thin film transistor 320 through the contact hole in the planarization layer 337.

The anode 344 may be formed of, for example, indium tin oxide (ITO), indium zinc oxide (IZO), or the like, which is a transparent conductive material.

The banks 342 disposed on the anode 344 and the planarization layer 337 serve to define and define pixels that actually emit light. The bank 342 may be formed of an organic material such as polyimide, acryl, or benzocyclobutene (BCB) resin.

The cathode 348 is disposed on the light emitting portion 346 and serves to supply electrons to the light emitting portion 346. [ Since the cathode 348 must supply electrons, the cathode 348 may be formed of a metal material such as magnesium (Mg), silver-magnesium (Ag: Mg) or the like, which is a conductive material having a low work function.

A light emitting portion 346 is disposed between the anode 344 and the cathode 348. The light emitting unit 350 may emit light and may include at least one of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. The structure of the organic light emitting diode display 200 Depending on the characteristics, some components may be omitted.

The hole injection layer and the hole transport layer are disposed between the anode 344 and the light emitting layer to smoothly move the hole from the anode 344 to the light emitting layer.

The hole injection layer is disposed on the anode 344 and serves to smoothly inject holes into the light emitting layer. The hole injection layer may be formed by, for example, HAT-CN (dipyrazino [2,3-f: 2 ', 3'-h] quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc NPD (N, N'-bis (naphthalene-1-yl) -N, N'-bis (phenyl) -2,2'-dimethylbenzidine).

The hole transporting layer is disposed on the hole injecting layer and serves to smoothly transfer holes to the light emitting layer. The hole transporting layer may be formed of, for example, NPD (N, N'-bis (naphthalene-1-yl) -N, N'- TAD (2,2 ', 7,7'-tetrakis (N, N-dimethylamino) -9,9-spirofluorene) - (3-methylphenyl) -N, N'- , And MTDATA (4,4 ', 4 "-Tris (N-3-methylphenyl-N-phenylamino) -triphenylamine).

Micro Cavity means that light of a specific wavelength is amplified by constructive interference because light is repeatedly reflected between two layers separated by an optical length. Since the wavelength of light emitted when the organic light emitting diode display 300 emits different light for each pixel is different, a resonance distance should be set for each wavelength of light emitted from each sub pixel in order to realize a micro cavity. In the organic light emitting diode display 300, the thickness of the hole transport layer may be adjusted to differently set the resonance distance for each pixel.

The light emitting layer is disposed on the hole transporting layer and can emit light of a specific color including a substance capable of emitting light of a specific color. In this case, the light emitting material may be formed using a phosphor or a fluorescent material.

A host material comprising CBP (4,4'-bis (carbazol-9-yl) biphenyl) or mCP (1,3-bis (carbazol-9-yl) benzene) , Acetylacetonate iridium, bis (1-phenylisoquinoline) acetylacetonate iridium, PQIr acac bis (1-phenylquinoline) acetylacetonate iridium, PQIr tris (1-phenylquinoline) iridium and PtOEP (octaethylporphyrin platinum A phosphorescent material, and a dopant. Or a fluorescent material containing PBD: Eu (DBM) 3 (Phen) or Perylene.

A phosphorescent material including a dopant material such as Ir complex including a host material including CBP or mCP and containing Ir (ppy) ₃ (tris (2-phenylpyridine) iridium) . Further, it may be made of a fluorescent material containing Alq ₃ (tris (8-hydroxyquinolino) aluminum).

When the light-emitting layer emits blue light, a dopant including a host material including CBP or mCP and containing FIrPic (bis (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium) (4,4'-bis (2,2-diphenyl-ethen-1-yl) biphenyl), DSA (1-4-di- [4- (N, N-di-phenyl) amino] styryl-benzene, PFO (polyfluorene) polymer and PPV (polyphenylenevinylene) polymer.

The electron transporting layer and the electron injecting layer are disposed between the light emitting layer and the cathode 348 to smooth the movement of electrons from the cathode 348 to the light emitting layer.

The electron transporting layer is disposed on the light emitting layer and serves to transfer electrons from the electron injecting layer to the light emitting layer. The electron transport layer may be formed of, for example, Liq (8-hydroxyquinolinolato-lithium), PBD (2- (4-biphenyl) -5- (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and BAlq (4-biphenyl) (bis (2-methyl-8-quinolinolate) -4- (phenylphenolato) aluminum).

The electron injection layer is an organic layer which is disposed on the electron transporting layer and smoothly injects electrons from the cathode 348. The electron injection layer is BaF2, LiF, NaCl, CsF, Li 2 O , and may be a metallic inorganic compound such as BaO, HAT-CN (dipyrazino [ 2,3-f: 2 ', 3'-h] quinoxaline-2, 3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine), and NPD (N, N'-bis (naphthalene- , And the like.

The cathode 348 is disposed on the light emitting portion 244 and serves to supply electrons to the light emitting portion 346. [ The cathode 348 may be formed of a metal material such as magnesium (Mg), silver-magnesium (Ag: Mg) or the like, which is a conductive material having a low work function, but is not limited thereto.

Or the OLED display 300 is a top emission type cathode, the cathode 348 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide Zinc oxide (ITZO), zinc oxide (ZnO), and tin oxide (TiO 2).

A protective layer 350 may be disposed on the cathode 348 to prevent the organic light emitting device 340 from being contaminated or damaged from the outside. The protective layer 350 may be formed of a single layer or a plurality of layers of organic or inorganic materials. no.

4 is a cross-sectional view of a first thin film transistor 400 included in an OLED display according to an exemplary embodiment of the present invention.

Here, the first thin film transistor 400 may be used for a switching transistor, but the present invention is not limited thereto, and the first thin film transistor 400 may be selectively arranged according to the structure and characteristics of the organic light emitting display.

4, the first thin film transistor 400 includes a shielding layer 414, a gate electrode 422, a source electrode 424, a drain electrode 426, and a semiconductor layer 428.

(SiOx), silicon nitride (SiNx), or the like is formed on the substrate 410 having a flexible characteristic such as a polyimide to prevent penetration of moisture or the like from the outside. The buffer layer 412a and the second buffer layer 412b may be stacked in this order. At this time, the buffer layer may be omitted depending on the structure or characteristics of the OLED display.

A shielding layer 414 is disposed on the first buffer layer 412a to minimize the influence of the semiconductor layer 428 on charges generated from the flexible substrate 410. [ At this time, the shielding layer 414 is formed of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium ), An alloy thereof, a single layer or a multilayer structure. The shielding layer 414 overlaps the semiconductor layer 428 between the substrate 410 and the semiconductor layer 428. Thus, by disposing the shielding layer 414 overlying the semiconductor layer 428, the semiconductor layer 428 can be protected to minimize the effects of charge from the substrate.

A second buffer layer 412b and a semiconductor layer 428 are sequentially stacked and disposed on the shielding layer 414.

The semiconductor layer 428 may be formed of polycrystalline silicon having better mobility than amorphous silicon or amorphous silicon or an oxide semiconductor such as ZnO or IGZO (Indium-Gallium-Zinc Oxide) having excellent mobility and uniformity characteristics have.

The semiconductor layer 428 may include a source region and a drain region that include p-type or n-type impurities and include a channel therebetween, and may further include a low concentration doping region between the source region and the drain region adjacent to the channel have.

A gate insulating layer 431 composed of a single layer or a plurality of layers of silicon oxide (SiOx) or silicon nitride (SiNx) is disposed on the semiconductor layer 428 so that a current flowing in the semiconductor layer 428 flows into the gate electrode 422 Do not flow.

The first contact hole CH1 is formed such that the upper portion of the shielding layer 414 is exposed while simultaneously penetrating the second buffer layer 412b and the gate insulating layer 431 in the region not overlapped with the semiconductor layer 428. [

A gate electrode 422 and a connection electrode 416 are disposed on the gate insulating layer 431. have. At this time, the gate electrode 422 overlaps the semiconductor layer 428 and the connection electrode 416 overlaps the first contact hole CH1.

The gate electrode 422 is connected to the gate line of the thin film transistor 400 and functions as a switch of the thin film transistor 400 through a signal transmitted from the outside. The gate electrode 422 may be formed of a conductive metal such as copper (Cu) (Mo), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and the like or an alloy thereof. have.

The connection electrode 416 may be formed at the same time when the gate electrode 422 is formed in the same layer as the gate electrode 422. At this time, the connection electrode 416 is directly connected to the shield layer 414 exposed through the first contact hole CH1, spaced apart from the gate electrode 422. [

An interlayer insulating layer 433 may be disposed on the gate electrode 422 to insulate the gate electrode 422 and the source electrode 424 and the drain electrode 426 from each other.

The second contact hole CH2 is formed through the interlayer insulating layer 433 and the gate insulating layer 431 and the third contact hole CH3 is formed through the interlayer insulating layer 433. [ The second contact hole CH2 is formed to expose the top of the semiconductor layer 428 and the third contact hole CH3 is formed such that the top of the connection electrode 416 is exposed.

A source electrode 424 and a drain electrode 426 connected to the semiconductor layer 428 are disposed on the interlayer insulating layer 433.

The source electrode 424 and the drain electrode 426 serve to transmit an electric signal transmitted from the outside to the organic light emitting diode from the thin film transistor 400 and are electrically connected to the semiconductor layer 428 through the second contact hole CH2, Directly connected. The source electrode 424 and the drain electrode 426 may be formed of a conductive metal such as copper, aluminum, molybdenum, chromium, gold, titanium, nickel, , And neodymium (Nd), or an alloy thereof, and may be composed of a single layer or multiple layers.

The source electrode 424 is directly connected to the connection electrode 416 through the third contact hole CH3. The source electrode 424 and the shielding layer 414 are electrically connected to each other so that the semiconductor layer 428 disposed on the top of the shielding layer 414 can minimize the influence of the charge received from the flexible substrate 410 have.

A passivation layer 435 formed of an inorganic insulating film such as silicon oxide (SiOx) or silicon nitride (SiNx) may be disposed on the source electrode 424 and the drain electrode 426 to prevent contamination from the outside.

5 is a cross-sectional view of a second thin film transistor 500 included in an organic light emitting display according to an embodiment of the present invention.

At this time, the second thin film transistor 500 may be used as a driving transistor, but the present invention is not limited thereto, and the second thin film transistor 500 may be selectively arranged according to the structure and characteristics of the OLED display.

5, the second thin film transistor 500 includes a shielding gate electrode 514, a source electrode 524, a drain electrode 526, and a semiconductor layer 528.

In order to prevent penetration of moisture or the like from the outside onto the substrate 510 having a flexible characteristic such as polyimide, a silicon oxide (SiOx) or a silicon (Si) film is formed like the first thin film transistor 400 described in FIG. The first buffer layer 512a and the second buffer layer 512b may be stacked in this order on a single layer or a plurality of layers of nitride (SiNx).

The influence of the semiconductor layer 528 from the charge generated from the flexible substrate 510 on the same layer as the shielding layer 414 of the first thin film transistor 400 described in FIG. 4 is minimized on the first buffer layer 512a A shield gate electrode 514 serving as a valve of the thin film transistor 500 is disposed through a signal transmitted from the outside in connection with the gate line. At this time, the shielding gate electrode 514 is formed of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), and neodymium Nd), or an alloy thereof, and may be composed of a single layer or multiple layers. The shielding gate electrode 514 overlaps the semiconductor layer 528 between the substrate 510 and the semiconductor layer 528. Accordingly, the shielding gate electrode 514 is arranged so as to overlap with the semiconductor layer 528, so that the semiconductor layer 528 can be protected from the influence of the charge from the substrate 510.

The second buffer layer 512b formed on the shielding gate electrode 514 in the same layer as the second buffer layer 412b of the first thin film transistor 400 described in FIG. 4 is substantially the same as the first thin film Shielding gate electrode 514 so that the current flowing in the semiconductor layer 528 does not flow to the shielding gate electrode 514. [

The semiconductor layer 528 disposed on the second buffer layer 512b may be made of amorphous silicon or polycrystalline silicon having better mobility than amorphous silicon or ZnO Or an oxide semiconductor such as IGZO (Indium-Gallium-Zinc Oxide).

The semiconductor layer 528 may include a source region and a drain region including a p-type or an n-type impurity and includes a channel therebetween, and may further include a lightly doped region between the source region and the drain region adjacent to the channel .

At this time, due to the difference in the structure of the thin film transistor, the first thin film transistor 400 and the second thin film transistor 500 are formed at different positions in the channel. The channel of the first thin film transistor 400 is formed at the interface between the semiconductor layer 428 and the gate insulating layer 431. On the other hand, the channel of the second thin film transistor 500 is formed at the interface between the second buffer layer 512b and the semiconductor layer 528. [ Accordingly, different characteristics are formed between the two thin film transistors, and the difference in characteristics between the thin film transistors is described in FIGS. 6A to 6B.

A single layer of silicon oxide (SiOx) or silicon nitride (SiNx), which is the same layer as the gate insulating layer 431 and the interlayer insulating layer 433 of the first thin film transistor 400 described in FIG. 4 described on the semiconductor layer 528, A gate insulating layer 531 and an interlayer insulating layer 533 made of a layer or a plurality of layers are disposed.

The fourth contact hole CH4 is formed through the interlayer insulating layer 533 and the gate insulating layer 531 so that the upper portion of the semiconductor layer 528 is exposed.

A source electrode 524 and a drain electrode 526 connected to the semiconductor layer 528 are disposed on the interlayer insulating layer 533.

The source electrode 524 and the drain electrode 526 transmit external electrical signals from the thin film transistor 500 to the organic light emitting diode and pass through the fourth contact hole CH4 to the semiconductor layer 528, Directly connected. The source electrode 524 and the drain electrode 526 may be formed of a conductive metal such as copper, aluminum, molybdenum, chromium, gold, titanium, nickel, , And neodymium (Nd), or an alloy thereof, and may be composed of a single layer or multiple layers.

A passivation layer 535 formed of an inorganic insulating film such as silicon oxide (SiOx) or silicon nitride (SiNx) may be disposed on the source electrode 524 and the drain electrode 526 to prevent contamination from the outside.

The fifth contact hole CH5 is formed on the drain electrode 526 such that the upper portion of the semiconductor layer 528 is exposed through the passivation layer 535 and the electrode included in the organic light emitting diode 540 is electrically connected to the drain electrode 526 ).

The detailed structure of the organic light emitting diode 540 directly connected to the second thin film transistor 500 on the passivation layer 535 is substantially the same as the structure and function described with reference to FIG. 3, and a detailed description thereof will be omitted.

6A and 6B are transfer curves showing characteristics of the first thin film transistor and the second thin film transistor included in the organic light emitting diode display according to the embodiment of the present invention.

6A and 6B, when the gate voltage Vg on the horizontal axis is applied to the first thin film transistor and the second thin film transistor, the ordinate indicates the current value Ids flowing between the source electrode and the drain electrode. At this time, the voltage (Vds) applied to the source electrode and the drain electrode can be changed and measurement is possible.

When the gate voltage is applied, the channel begins to be formed, the current rapidly increases, the channel is completely formed, and the current flows constantly.

Referring to FIG. 6A in which the first thin film transistor is measured and FIG. 6B in which the second thin film transistor is measured, when the channel begins to be formed and the current rapidly increases in the region where the first thin film transistor is larger than the second thin film transistor .

In the case of a driving transistor for supplying a current to the organic light emitting element, it is difficult to control the current when the amount of change at a low voltage is large, so that the luminance of the organic light emitting element is changed and appears as a stain on the panel. However, in the case of a switching transistor, a large amount of current change can be performed to perform a switching function. Since such characteristics can be applied to the first thin film transistor and the second thin film transistor, it is possible to obtain an effect of fabricating devices having two characteristics in one panel at the same time. Accordingly, when a thin film transistor having various characteristics is disposed, a thin film transistor capable of minimizing a change in undesired characteristics that may be caused by a change in a process or structure of another thin film transistor through a minimized change in a common structure can do.

The organic light emitting display according to an embodiment of the present invention may be applied to a display device including a TV, a mobile, a tablet PC, a monitor, a laptop computer, And the like. The present invention can also be applied to a vehicle lighting device, a wearable display device, a foldable display device, a rollable display device, a curved display device, and a bendable display device.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a shielding layer on the flexible substrate, a plurality of thin film transistors including a gate electrode, a source electrode, a drain electrode and a semiconductor layer on a flexible substrate, At least one of the organic light emitting element and the plurality of thin film transistors includes a thin film transistor in which the gate electrode and the shielding layer are the same layer.

The shielding layer of the organic light emitting diode display according to the embodiment of the present invention overlaps with the semiconductor layers included in the plurality of thin film transistors.

In the organic light emitting display according to an embodiment of the present invention, one of the electrodes including at least one of the remaining transistors, which is different from the thin film transistor having the gate electrode and the shielding layer, is connected to the shielding layer.

The organic light emitting display according to an embodiment of the present invention further includes a connection electrode in the same layer as at least one of the gate electrodes of the remaining transistors and the connection electrode includes one of the electrodes included in at least one of the remaining transistors, Connect.

In the organic light emitting display according to an embodiment of the present invention, the thin film transistor having the gate electrode as the same layer as the shielding layer is directly connected to the organic light emitting device.

In the organic light emitting diode display according to the embodiment of the present invention, the amount of change in the driving current Ids according to the gate voltage Vgs is smaller than that of at least one of the remaining transistors in the thin film transistor having the same layer as the gate electrode.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a shielding layer on the flexible substrate, a plurality of thin film transistors on the flexible substrate, and an organic light emitting element on the plurality of thin film transistors, At least one thin film transistor of the thin film transistor has a gate electrode of the at least one thin film transistor in the same layer as the shielding layer so that a variation amount of the driving current (Ids) according to the gate voltage (Vgs) is minimized.

In the organic light emitting display according to an embodiment of the present invention, the shield layer overlaps with at least one thin film transistor to protect at least one thin film transistor from the influence of electric charge generated in the flexible substrate.

In the organic light emitting display according to the embodiment of the present invention, one of the electrodes included in at least one thin film transistor is directly connected to the shield layer.

In the organic light emitting display according to an embodiment of the present invention, the thin film transistor having the gate electrode as the same layer as the shielding layer is directly connected to the organic light emitting device.

An organic light emitting display according to an embodiment of the present invention includes a flexible substrate, a plurality of shielding layers on a flexible substrate, a first thin film transistor and a second thin film transistor on a plurality of shielding layers, The first thin film transistor and the second thin film transistor each include a gate electrode, a semiconductor layer, a source electrode, and a drain electrode, and the gate electrode included in the first thin film transistor includes a semiconductor layer And the gate electrode included in the second thin film transistor is in the same layer as the shielding layer.

In the shielding layer of the organic light emitting display according to the embodiment of the present invention, the semiconductor layers included in the first thin film transistor or the second thin film transistor overlap each other.

In the OLED display according to the embodiment of the present invention, the source electrode or the gate electrode included in the first thin film transistor is connected to the shield layer.

The organic light emitting display according to an embodiment of the present invention is characterized in that the source electrode or the gate electrode included in the first thin film transistor is connected to the gate electrode of the first thin film transistor through the connection electrode in the same layer as the gate electrode of the first thin film transistor, Layer.

In the organic light emitting diode display according to the embodiment of the present invention, the second thin film transistor and the organic light emitting diode are directly connected.

In the organic light emitting display according to the embodiment of the present invention, the second thin film transistor has a smaller change amount of the driving current Ids according to the gate voltage Vgs than the first thin film transistor.

The channel of the first thin film transistor is formed on the upper surface of the semiconductor layer, and the channel of the second thin film transistor is formed on the lower surface of the semiconductor layer in the organic light emitting display according to the embodiment of the present invention.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

100, 200, 300: organic light emitting display
110: image processor 120: timing controller
130: Data driver 140: Gate driver
150: display panel 160: pixel
210: gate line 220: data line
230: switching transistor 240: driving transistor
250: compensation circuit
260, 340, 540: organic light emitting element
310, 410, 510: substrate
312: buffer layer
314, 414: shielding layer
320, 400, 500: thin film transistor
322, 422: gate electrode
324, 424, 524: source electrode
326, 426, 526: drain electrode
328, 428, 528: semiconductor layer
331, 431, 531: Gate insulating layer
333, 433, 533: an interlayer insulating layer
335, 435, 535: passivation layer
337: planarization layer 342:
344: anode 346:
348: Cathode 350: Protective layer
416: connecting electrode
412a, 512a: first buffer layer
412b, 512b: second buffer layer
514: shielded gate electrode

Claims (17)

A flexible substrate;
A shielding layer on the flexible substrate;
A plurality of thin film transistors including a gate electrode, a source electrode, a drain electrode, and a semiconductor layer on the flexible substrate;
An organic light emitting element on the plurality of thin film transistors; And
Wherein at least one of the plurality of thin film transistors is a thin film transistor in which the gate electrode and the shielding layer are the same layer. The organic light emitting diode display according to claim 1, wherein the shield layer overlaps the semiconductor layers included in the plurality of thin film transistors. The organic light emitting diode display of claim 1, wherein one of the electrodes including at least one of the remaining transistors different from the thin film transistor having the same layer as the gate electrode and the shielding layer is connected to the shielding layer. The plasma display apparatus of claim 3, further comprising a connection electrode on the same layer as the gate electrode of at least one of the remaining transistors, wherein the connection electrode connects one of the electrodes included in at least one of the remaining transistors to the shield layer Organic light emitting display. The organic light emitting diode display according to claim 1, wherein the thin film transistor having the same gate electrode as the shielding layer is directly connected to the organic light emitting element. The organic light emitting diode display according to claim 1, wherein the thin film transistor having the same gate electrode layer as the shielding layer has a smaller change amount of the driving current (Ids) according to the gate voltage (Vgs) than at least one of the remaining transistors. A flexible substrate;
A shielding layer on the flexible substrate;
A plurality of thin film transistors on the flexible substrate; And
And an organic light emitting element on the plurality of thin film transistors,
Wherein at least one thin film transistor of the plurality of thin film transistors has a gate electrode of the at least one thin film transistor being the same layer as that of the shield layer so that a variation amount of a driving current Ids according to a gate voltage . The organic light emitting diode display according to claim 7, wherein the shield layer overlaps the at least one thin film transistor and protects the at least one thin film transistor from the influence of charges generated in the flexible substrate. The organic light emitting diode display according to claim 8, wherein one of the electrodes included in the at least one thin film transistor and the shield layer are directly connected. The organic light emitting diode display according to claim 7, wherein the thin film transistor having the gate electrode as the same layer as the shielding layer is directly connected to the organic light emitting element. A flexible substrate;
A plurality of shielding layers on the flexible substrate;
A first thin film transistor and a second thin film transistor on the plurality of shield layers; And
And an organic light emitting element on the first thin film transistor and the second thin film transistor,
The first thin film transistor and the second thin film transistor each include a gate electrode, a semiconductor layer, a source electrode, and a drain electrode,
Wherein the gate electrode included in the first thin film transistor is on the semiconductor layer and the gate electrode included in the second thin film transistor is the same layer as the shield layer. 12. The organic light emitting diode display according to claim 11, wherein the shielding layer overlaps the semiconductor layers included in the first thin film transistor or the second thin film transistor. The organic light emitting diode display according to claim 11, wherein a source electrode or a gate electrode included in the first thin film transistor is connected to the shield layer. 14. The thin film transistor of claim 13, wherein a source electrode or a gate electrode included in the first thin film transistor is connected to a shielding layer below the first thin film transistor through a connection electrode in the same layer as the gate electrode of the first thin film transistor, And an organic light emitting display device connected thereto. 12. The OLED display of claim 11, wherein the second thin film transistor and the organic light emitting diode are directly connected. The organic light emitting display according to claim 11, wherein the second thin film transistor has a smaller change amount of a driving current (Ids) according to a gate voltage (Vgs) than the first thin film transistor. 12. The OLED display of claim 11, wherein a channel of the first thin film transistor is formed on a top surface of the semiconductor layer, and a channel of the second thin film transistor is formed on a bottom surface of the semiconductor layer.

Images