KR102294114B1 - Display device - Google Patents

Abstract

A display device according to the present invention includes a substrate, a first conductive layer formed on the substrate, a first thin film transistor formed on and on the first conductive layer, the first thin film transistor having a first input terminal, a first output terminal, and a first control terminal; It includes a pixel electrode connected to the first thin film transistor, the first conductive layer overlaps the first thin film transistor, and is electrically connected to the first input terminal.

Description

display device {DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to an organic light emitting display device.

An organic light emitting diode display includes an organic light emitting element and a plurality of thin film transistors for driving the organic light emitting element. These are made of a plurality of thin films, and for reasons of process, the thin film transistor is usually located at the bottom and the organic light emitting device at the top, the anode of the organic light emitting device at the bottom and the cathode at the top.

Such an organic light emitting diode display may be divided into a top emission method in which light is emitted upward and a bottom emission method in which light is emitted downward. In the case of the bottom emission method, a light blocking member (black matrix) is not formed under the thin film transistor because an area capable of emitting light is narrow due to the thin film transistor positioned below the organic light emitting diode.

Meanwhile, a semiconductor of a thin film transistor for driving a display device may be formed of polycrystalline silicon formed by crystallizing amorphous silicon.

However, if the light blocking member is not formed, there is a problem in that a polarizing plate must be separately added to prevent light scattering.

In addition, when amorphous silicon is polycrystallized, electrical characteristics of the thin film transistor formed are not uniform, so there is a problem in that the image quality is not uniform.

Accordingly, an object of the present invention is to provide a display device capable of reducing a kink effect, reducing a saturation voltage, and obtaining a uniform image quality without installing a polarizer.

A display device according to the present invention for achieving the above object includes a substrate, a first auxiliary electrode formed on the substrate, and a first auxiliary electrode formed thereon, and a first input terminal, a first output terminal, and a first control terminal A first thin film transistor having a , a pixel electrode connected to the first thin film transistor, wherein the first auxiliary electrode overlaps the first thin film transistor and is electrically connected to the first input terminal.

The first thin film transistor includes polycrystalline silicon including a first source region heavily doped with impurities, a first drain region, and a first channel region formed between the first source region and the first drain region, The first auxiliary electrode is connected to the first input terminal via the first source region.

The first auxiliary electrode is directly connected to the first input electrode.

The first auxiliary electrode may be formed of an opaque conductive material.

The first auxiliary electrode may be made of a transparent conductive material.

The first auxiliary electrode may be formed on the entire surface of the substrate.

a first signal line, a second signal line crossing the first signal line, a second output terminal connected to the first control terminal of the first thin film transistor, a second control terminal connected to the first signal line, and a second signal line connected to A second thin film transistor including a second input terminal, the second auxiliary electrode overlapping the second thin film transistor, and electrically connected to the second input terminal may be further included.

The second thin film transistor includes polycrystalline silicon including a second source region and a second drain region doped with a high concentration of impurities and a second channel region between the second source region and the second drain region, and a second auxiliary electrode is connected to the second input electrode via the second source region.

The second auxiliary electrode is directly connected to the first input electrode.

The second auxiliary electrode may be formed of an opaque conductive material.

It may further include a light emitting layer formed on the pixel electrode.

As in the embodiment of the present invention, if the gate connected to the source is formed under the semiconductor using the auxiliary electrode, the kink effect is reduced and the stable voltage is reduced to obtain a uniform image quality.

1 is an equivalent circuit diagram of an organic light emitting diode display according to an exemplary embodiment.
2 is a layout view of an organic light emitting diode display according to an exemplary embodiment.
3 is a cross-sectional view illustrating the organic light emitting diode display of FIG. 2 taken along line III-III.
4 is a cross-sectional view illustrating the organic light emitting diode display of FIG. 2 taken along line IV-IV.
5 and 6 are cross-sectional views of an organic light emitting diode display according to another exemplary embodiment, taken along line III-III of FIG. 2 .

Then, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them.

In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. Throughout the specification, like reference numerals are assigned to similar parts. When a part of a layer, film, region, plate, etc. is said to be “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle.

First, an organic light emitting diode display according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1 .

1 is an equivalent circuit diagram of an organic light emitting diode display according to an exemplary embodiment.

Referring to FIG. 1 , the organic light emitting diode display according to the present exemplary embodiment includes a plurality of signal lines 121 , 171 , and 172 and a plurality of pixels PX connected thereto and arranged in a substantially matrix form. ) is included.

The signal line includes a plurality of gate lines 121 transmitting a gate signal (or a scan signal), a plurality of data lines 171 transmitting a data signal, and a plurality of driving voltage lines transmitting a driving voltage. (driving voltage line) 172 . The gate lines 121 extend approximately in the row direction and are substantially parallel to each other, and the data lines 171 extend approximately in the column direction and are approximately parallel to each other. The driving voltage line 172 extends approximately in the column direction.

Each pixel PX includes a switching transistor Qs, a driving transistor Qd, a storage capacitor Cst, and an organic light emitting element LD. include

The switching transistor Qs has a control terminal, an input terminal, and an output terminal, the control terminal is connected to the gate line 121, the input terminal is the data line 171 ), and the output terminal is connected to the driving transistor Qd. The switching transistor Qs transmits the data signal received from the data line 171 to the driving transistor Qd in response to the scan signal received from the gate line 121 .

The driving transistor Qd also has a control terminal, an input terminal, and an output terminal. The control terminal is connected to the switching transistor Qs, the input terminal is connected to the driving voltage line 172 , and the output terminal is an organic light emitting diode. connected to (LD). The driving transistor Qd flows an _{output current I LD} whose magnitude varies according to a voltage applied between the control terminal and the output terminal.

The capacitor Cst is connected between the control terminal and the input terminal of the driving transistor Qd. The capacitor Cst charges the data signal applied to the control terminal of the driving transistor Qd and maintains it even after the switching transistor Qs is turned off.

The organic light emitting diode LD is, for example, an organic light emitting diode (OLED), an anode connected to the output terminal of the driving transistor Qd, and a cathode connected to the common voltage line 172 . (cathode) has The organic light emitting diode LD displays an image by emitting light with different intensity according to _{the output current I LD of the driving transistor Qd.}

The switching transistor Qs and the driving transistor Qd are n-channel field effect transistors (FETs), and at least one of them may have a structure as shown in FIG. 2 . However, at least one of the switching transistor Qs and the driving transistor Qd may be a p-channel field effect transistor. Also, the connection relationship between the transistors Qs and Qd, the capacitor Cst, and the organic light emitting diode LD may be changed. That is, in some embodiments, the driving transistor Qd may be a p-channel field effect transistor, and the switching transistor Qs may be an n-channel field effect transistor.

In some cases, in addition to the switching transistor Qs and the driving transistor Qd, there may be other transistors for compensating the threshold voltage of the driving transistor Qd or the organic light emitting diode LD.

Next, a detailed structure of the organic light emitting diode display shown in FIG. 1 will be described in detail with reference to FIGS. 2 to 4 together with FIG. 1 .

2 is a layout view of an organic light emitting diode display according to an exemplary embodiment, FIG. 3 is a cross-sectional view of the organic light emitting diode display of FIG. 2 taken along line III-III, and FIG. 4 is the organic light emitting diode display of FIG. It is a cross-sectional view showing the display device cut along the IV-IV line.

2 to 4 , the auxiliary electrode 10 is formed on the insulating substrate 110 made of transparent glass or plastic. The auxiliary electrode 10 is made of an opaque conductive material.

A blocking layer 111 made of silicon oxide or silicon nitride is formed on the substrate 110 including the auxiliary electrode 10 . The blocking layer 111 includes a contact hole 15 exposing the auxiliary electrode 10 .

First and second semiconductors 151a and 151b are formed on the blocking layer 111 , and a capacitor semiconductor 157 is connected to the second semiconductor 151b.

The first and second semiconductors 151a and 151b overlap the auxiliary electrode 10 and are connected to the auxiliary electrode 10 through the contact hole 15 . The first and second semiconductors 151a and 151b are made of polycrystalline silicon obtained by crystallizing amorphous silicon.

The first and second source regions 153a and 153b and the first and second drain regions 155a and 155b of the first and second semiconductors 151a and 151b are doped with n-type or p-type impurities, respectively. It may be doped with other impurities. A lightly doped region 152 or an offset region is formed between the first and second source regions 153a and 153b and the channel regions 154a and 154b and between the first drain regions 155a and 155b and the channel regions 154a and 154b. can be formed.

A heavily doped region 154c may be included between the first source region and the first drain regions 153a and 155a and used as the drain and source regions.

The semiconductor connected to the auxiliary electrode 10 is also preferably doped with a high concentration of conductive impurities, and may be, for example, the source regions 153a and 153b.

A gate insulating layer 140 made of silicon oxide or silicon nitride is formed on the first and second semiconductors 151a and 151b.

A gate line 121 including a first control electrode 124a and a second control electrode 124b are formed on the gate insulating layer 140 .

The gate line 121 mainly extends in the horizontal direction, and the first control electrode 124a protrudes upward and overlaps the channel portion 154a of the switching transistor. The gate line 121 may include a wide end (not shown) for connection to another layer or an external driving circuit.

The second control electrode 124b is separated from the gate line 121 and overlaps the channel portion 154b of the driving thin film transistor.

The second control electrode 124b includes a storage electrode 127 elongated in the vertical direction, and the storage electrode 127 overlaps the storage electrode part 157 of the semiconductor.

A first interlayer insulating layer 180p is formed on the gate line 121 , the second control electrode 124b , and the storage electrode 127 , and a data line 171 that transmits a data signal on the first interlayer insulating layer 180p . ), a driving voltage line 172 , and first and second output electrodes 175a and 175b are formed.

The data line 171 and the driving voltage line 172 mainly extend in a vertical direction to cross the gate line 121 . The data line 171 includes a first input electrode 173a extending toward the first control electrode 124a, and the driving voltage line 172 includes a second input electrode 173b extending toward the second control electrode 124b. includes

The first and second input electrodes 173a and 173b are respectively connected to the first and second source regions 153a and 153b through the contact holes 161 and 164 formed in the first interlayer insulating layer 180p and the gate insulating layer 140 . is connected with

The first and second output electrodes 175a and 175b are separated from each other and also from the data line 171 and the driving voltage line 172 . The first output electrode 175a is connected to the first drain region 155a and the second input electrode 124b through the contact holes 162 and 163 formed in the first interlayer insulating layer 180p and the gate insulating layer 140 . and the second output electrode 175b is connected to the second drain region 155b through the contact hole 165 formed in the first interlayer insulating layer 180p and the gate insulating layer 140 .

The first input electrode 173a and the first output electrode 175a face each other with the first control electrode 124a as the center, and the second input electrode 173b and the second output electrode 175b are the second control electrode They face each other around (124b).

The first control electrode 124a, the first input electrode 173a, and the first output electrode 175a form a switching thin film transistor (TFT) Qs together with the first semiconductor 151a, and the second The control electrode 124b, the second input electrode 173b, and the second output electrode 175b together with the second semiconductor 151b form the driving thin film transistor Qd.

The structures of the switching thin film transistor Qs, the driving thin film transistor Qd, the gate line 121 , the data line 171 , and the driving voltage line 172 described above are only one example, and there may be various other examples.

A second interlayer insulating layer 180q is formed on the data line 171 , the driving voltage line 172 , and the first and second output electrodes 175a and 175b . The second interlayer insulating layer 180q includes a lower layer (not shown) made of an inorganic insulating material such as silicon nitride or silicon oxide, and an upper layer (not shown) made of an organic insulating material. The organic insulator preferably has a dielectric constant of 4.0 or less, may have photosensitivity, and may provide a flat surface. The passivation layer 180 may have a single layer structure made of an inorganic insulating material or an organic insulating material.

A contact hole 185 exposing the second output electrode 175b is formed in the second interlayer insulating layer 180q.

A pixel electrode 191 is formed on the second interlayer insulating layer 180q.

The pixel electrode 191 is made of a transparent material made of ITO or IZO, and is connected to the second output electrode 175b through the contact hole 185 .

A partition 360 is formed on the pixel electrode 191 . The barrier rib 360 surrounds the edge of the pixel electrode 191 like a bank to define an opening 365 , and may be made of an organic insulating material or an inorganic insulating material, particularly a photosensitive material containing a black pigment. In this case, the barrier rib 360 serves as a light blocking member, and the formation process thereof is simple.

An organic light emitting member 370 is formed in the opening 365 above the pixel electrode 191 defined by the barrier rib 360 . The organic light emitting member 370 may have a multilayer structure including a light emitting layer and an auxiliary layer for increasing the efficiency of the light emitting layer.

The emission layer may be made of an organic material that uniquely emits light of any one of primary colors such as red, green, and blue three primary colors, or a mixture of an organic material and an inorganic material. An organic light emitting diode display displays a desired image by spatial sum of primary color light emitted from an emission layer.

The auxiliary layer includes a hole transport layer for balancing electrons and holes, an electron transport layer, and an electron injecting layer and an electron injection layer to enhance injection of electrons and holes. injecting layer).

A common electrode 270 is formed on the light emitting member 370 over the entire surface of the substrate.

The common electrode 270 may be made of a conductive material that has good electron injection and does not affect an organic material, and may include a reflective metal such as molybdenum, chromium, silver, aluminum, or an alloy thereof.

In such an organic light emitting diode display, the pixel electrode 191 , the organic light emitting member 370 , and the common electrode 270 form an organic light emitting diode LD, the pixel electrode 191 is an anode, and the common electrode 270 is a cathode. becomes

The organic light emitting display device displays an image by emitting light downwards from the substrate 110 , and the light emitted from the organic light emitting member 370 is reflected by the common electrode 270 and faces downward.

In this case, the thickness of at least one of the organic light emitting member, the pixel electrode 191 and the common electrode 270 is adjusted to have a fine resonance structure that amplifies the wavelength of the color emitted according to the red, green, and blue pixels. can Such a microresonant structure amplifies light of a specific wavelength by constructive interference by repeatedly reflecting between the pixel electrode 191 and the common electrode 270 that are spaced apart by an optical path length, for example, a pixel electrode. A specific wavelength can be strengthened by forming the thickness of (191) differently in the order of red>green>blue.

In the embodiment of the present invention, an auxiliary electrode is formed with a conductive material under the semiconductor and electrically connected to the auxiliary electrode, so that the auxiliary electrode connected to the source electrode operates as a gate electrode of the thin film transistor, so that a channel is also formed between the buffer layer and the semiconductor. It can reduce the kink effect and the stabilizing voltage because of the formation.

In addition, since the auxiliary electrode is formed of an opaque material to cover it, light leakage in the thin film transistor can be prevented, and external light can also be prevented from affecting the thin film transistor.

[Second embodiment]

5 is a cross-sectional view of an organic light emitting diode display according to another exemplary embodiment of the present invention, and is a cross-sectional view taken along line III-III of FIG. 2 .

Since most of the interlayer structures are the same as those of the organic light emitting diode display of the first embodiment, only other parts will be described in detail.

In the organic light emitting diode display of FIG. 5 , the source electrodes 173a and 173b are connected to the auxiliary electrode 10 through the contact hole 15 . In the first embodiment, the auxiliary electrode 10 is connected through the source regions 153a and 153b connected to the source electrodes 173a and 173b, but in the second embodiment, the source electrodes 173a and 173b and the auxiliary electrode 10 are connected. This is directly connected.

[Third embodiment]

6 is a cross-sectional view of an organic light emitting diode display according to another exemplary embodiment of the present invention, and is a cross-sectional view taken along line III-III of FIG. 2 .

Since most of the interlayer structures are the same as those of the organic light emitting diode display of the first embodiment, only other parts will be described in detail.

In the organic light emitting diode display of FIG. 6 , the auxiliary electrode 10 is formed of a transparent conductive material such as ITO or IZO instead of an opaque conductive material, and is formed on the entire surface of the substrate 110 unlike the second embodiment. Therefore, since it is not necessary to use a photolithography process to form the auxiliary electrode 10 , the manufacturing process can be simplified. In the structure of FIG. 6 , a polarizing plate may be partially disposed in order to prevent external light from affecting the thin film transistor and to prevent external light from being scattered to reduce image quality.

Also, as in the second embodiment, the source electrode 173a and the auxiliary electrode 10 may be directly connected.

110: insulating substrate 121: gate line
124a, 124a: control electrode 127: sustain electrode
140: gate insulating films 154a, 154b: semiconductor
163a, 163b, 165a, 165b: ohmic contact member
171: data line 172: driving voltage line
173a, 173b: input electrodes 175a, 175b: output electrodes
180p, 180q: interlayer insulating film
161, 162, 163, 164, 165, 185: contact hole
191: pixel electrode 270: common electrode
360: bulkhead
365: opening 370: organic light emitting member
Cst: holding capacitor I _LD : driving current
LD: organic light emitting element PX: pixel
Qs: switching transistor Qd: driving transistor

Claims (13)

Board,
a first auxiliary electrode formed on the substrate;
a blocking layer covering the first auxiliary electrode;
a first semiconductor formed on the blocking layer;
a gate insulating film formed on the first semiconductor;
a control electrode formed on the gate insulating film;
an interlayer insulating film covering the control electrode and the gate insulating film;
a first input electrode and a first output electrode formed on the interlayer insulating layer;
A plurality of driving voltage lines that transmit a driving voltage and extend in one direction;
a plurality of data lines carrying data signals, and
A pixel electrode formed on an upper layer than the first input electrode and the first output electrode
including,
The first semiconductor, the first input electrode, the first output electrode, and the control electrode constitute a first thin film transistor,
The first semiconductor includes a first source region and a first drain region, and a channel region formed between the first source region and the first drain region;
the first auxiliary electrode continuously overlaps the first semiconductor from the first source region of the first semiconductor to the first drain region through the channel region;
the first input electrode is directly connected to the first auxiliary electrode through a contact hole formed in the blocking layer and the interlayer insulating layer;
the first input electrode is directly connected to the first source region of the first semiconductor through a contact hole formed in the interlayer insulating layer;
The control electrode of the first thin film transistor receives the data signal,
When the first thin film transistor is turned off, the first auxiliary electrode is not connected to the plurality of driving voltage lines and the driving voltage is not applied thereto. In claim 1,
The first auxiliary electrode is formed of an opaque conductive material or a transparent conductive material. In claim 1,
a first signal line crossing the data line;
a second thin film transistor including a second output electrode connected to the control electrode of the first thin film transistor, a control electrode connected to the first signal line, and a second input electrode connected to the data line;
and a second auxiliary electrode overlapping the second thin film transistor and electrically connected to the second input electrode of the second thin film transistor. In claim 3,
The second thin film transistor further includes a second semiconductor including a second source region and a second drain region and a channel region between the second source region and the second drain region. In claim 3,
The second auxiliary electrode is directly connected to the second input electrode of the second thin film transistor. 6. In claim 4 or 5,
The second auxiliary electrode is made of an opaque conductive material. In claim 1,
a light emitting layer formed on the pixel electrode; and
and a common electrode formed on the emission layer. Board,
a first auxiliary electrode formed on the substrate;
a first thin film transistor formed on the substrate and including a control electrode, a first input electrode, a first output electrode, and a first semiconductor;
a second thin film transistor formed on the substrate and including a control electrode, a second input electrode, a second output electrode, and a second semiconductor;
A plurality of driving voltage lines that transmit a driving voltage and extend in one direction;
a plurality of data lines carrying data signals, and
a pixel electrode electrically connected to a first output electrode of the first thin film transistor;
the first semiconductor includes a first source region and a first drain region, and a channel region formed between the first source region and the first drain region;
a control electrode of the first thin film transistor overlaps the channel region of the first semiconductor;
the first auxiliary electrode overlaps the control electrode of the first semiconductor and the first thin film transistor;
the first auxiliary electrode is located on a different layer from the control electrode of the first thin film transistor;
the first auxiliary electrode is electrically connected to the first source region of the first semiconductor;
the first input electrode of the first thin film transistor is directly connected to the first source region and the first auxiliary electrode of the first semiconductor without passing through another auxiliary electrode;
The first semiconductor and the second semiconductor are located on the same layer,
The control electrode of the first thin film transistor receives the data signal through the second thin film transistor,
When the first thin film transistor is turned off, the first auxiliary electrode is not connected to the plurality of driving voltage lines and the driving voltage is not applied thereto. In claim 8,
The first auxiliary electrode is formed of an opaque conductive material or a transparent conductive material. In claim 8,
The first auxiliary electrode continuously overlaps the first semiconductor from the first source region of the first semiconductor to the first drain region through the channel region. In claim 8,
It further comprises a second auxiliary electrode formed on the substrate,
the second semiconductor includes a second source region and a second drain region, and a channel region formed between the second source region and the second drain region;
the control electrode of the second thin film transistor overlaps the channel region of the second semiconductor;
the second auxiliary electrode overlaps the control electrode of the second semiconductor and the second thin film transistor;
the second auxiliary electrode is located on a different layer from the control electrode of the second thin film transistor;
voltages of the control electrode and the second auxiliary electrode of the second thin film transistor are different from each other;
the second auxiliary electrode is electrically connected to the second source region of the second semiconductor;
and the second input electrode of the second thin film transistor is directly connected to the second source region and the second auxiliary electrode of the second semiconductor without passing through another auxiliary electrode. In claim 8,
The control electrode and the first auxiliary electrode of the first thin film transistor are electrically insulated from each other. Board,
a first auxiliary electrode formed on the substrate;
a first thin film transistor formed on the substrate and including a control electrode, a first input electrode, a first output electrode, and a first semiconductor;
a second thin film transistor formed on the substrate and including a control electrode, a second input electrode, a second output electrode, and a second semiconductor;
A plurality of driving voltage lines that transmit a driving voltage and extend in one direction;
a plurality of data lines carrying data signals, and
a pixel electrode electrically connected to a first output electrode of the first thin film transistor;
the first semiconductor includes a first source region and a first drain region, and a channel region formed between the first source region and the first drain region;
the first auxiliary electrode overlaps the control electrode of the first semiconductor and the first thin film transistor;
the first auxiliary electrode is located on a different layer from the control electrode of the first thin film transistor;
the first auxiliary electrode is electrically connected to the first source region of the first semiconductor;
the first input electrode of the first thin film transistor is directly connected to the first source region and the first auxiliary electrode of the first semiconductor without passing through another auxiliary electrode;
The control electrode of the first thin film transistor receives the data signal through the second thin film transistor,
When the first thin film transistor is turned off, the first auxiliary electrode is not connected to the plurality of driving voltage lines, so that the driving voltage is not applied;
The first thin film transistor is a p-channel field effect transistor, and the second thin film transistor is an n-channel field effect transistor.

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