JP2008216529A - Organic el display and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use n-channel TFTs e.g. oxide TFTs as p-channel type TFTs as driving transistors of an organic EL display and to achieve large current drive by p-channel TFTs e.g. organic TFTs. <P>SOLUTION: The organic EL display comprises a thin film TFT circuit having a plurality of pixel circuits and an organic EL layer and each pixel circuit comprises first, second and third thin film TFTs. The gate electrode, the source electrode and the drain electrode of the first thin film TFT are connected to the gate line, the source line, the gate electrode of the second thin film TFT, and one electrode of a capacitor, respectively. The second thin film TFT is a p-channel type thin film TFT, the source electrode and the drain electrode of the second thin film TFT are connected to power supply potential, the gate of the third thin film TFT and one end of a resistor, respectively. The third thin film TFT is an n-channel type thin film TFT and the drain and the source of the third thin film TFT are connected to the power supply potential, the other terminal of the resistor and an anode, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an organic EL display which is one of flat panel displays.

Liquid crystal displays and plasma displays have been commercialized as flat panel displays. In general, a liquid crystal display has a problem that a viewing angle is narrow and responsiveness to a high-speed pixel signal is not sufficient. In addition, the plasma display consumes a large amount of power, and there is a problem that there are many technical problems to be solved in order to realize a larger size than that currently commercialized.

Recently, an organic electroluminescence display (organic EL display) using an organic light-emitting material has been attracting attention as a liquid crystal display or a plasma display. Since organic EL displays use organic compounds as light-emitting materials, they are expected to be capable of realizing flat panel displays with low power consumption that are self-luminous, have high response speed, and do not depend on viewing angle. .

The organic EL display includes a simple matrix type that does not use a thin film transistor (TFT) and an active matrix type that uses a TFT. The simple matrix type organic EL display has a plurality of parallel electrodes formed on a glass substrate, an organic EL layer, and a plurality of electrodes orthogonal to the plurality of parallel electrodes. In the simple matrix type organic EL display, there is a problem that the organic EL layer needs to emit light with high brightness in a selected moment, the organic EL layer is severely deteriorated, and the influence of wiring resistance is large. . On the other hand, in an active matrix organic EL display, a TFT circuit is formed on a glass substrate, an organic EL layer is formed thereon, and a counter electrode is further formed. Usually, amorphous silicon (a-Si) or polysilicon (p-Si) is used as a semiconductor constituting the TFT circuit. In addition, a type in which the counter electrode side is used as a cathode and light is extracted from the substrate side (downward emission type (bottom emission type)) is common.

However, when an amorphous silicon or polysilicon film is formed, a high temperature process of 250 ° C. or higher is required, and it is necessary to use glass as a substrate. A TFT using amorphous silicon or polysilicon is visible light and has photoconductivity, and therefore needs to be shielded from light. The light that can be extracted from the substrate side is limited to a portion obtained by subtracting the area of the opaque TFT. Therefore, an active matrix type organic EL display using amorphous silicon or polysilicon has a small aperture ratio (= light emitting area / pixel area), and in order to realize a sufficient image quality, it is not as high as a simple matrix but has a high luminance. It was necessary to emit light.

On the other hand, flexible displays are required in the world. The flexible display has features such as being light, thin, bent, and resistant to impact. However, since the plastic substrate used for the flexible display is vulnerable to heat, it cannot withstand high-temperature processes and it is difficult to use silicon-based materials.

Accordingly, what is attracting attention is a so-called “organic TFT” using an organic semiconductor as a semiconductor layer and a so-called “oxide TFT” using an oxide semiconductor as a semiconductor layer. Since these TFTs can be manufactured by a low temperature process of 200 ° C. or lower, they can be formed on a plastic substrate.

However, organic TFTs have a problem that only p-channel TFTs can be obtained stably and their mobility is as small as 1 cm ² / Vs or less. In addition, oxide TFTs have a problem that good characteristics can be obtained only with n-channel TFTs.

By the way, the TFT circuit connected to the organic EL has, as a basic structure, a scanning transistor and a driving transistor as shown in FIG. 11 (Non-Patent Document 1). The scanning transistor may be a p-channel type or an n-channel type, but high-speed response characteristics are required. The driving transistor is required to have a large current characteristic and is preferably a p-channel type.

2003 FPD Technology Taizen (electronic journal) p.684

The present invention has been made to solve the above problems, and an organic EL display in which an n-channel TFT such as an oxide TFT can be used like a p-channel type as a driving transistor of an organic EL display. The challenge is to achieve this. It is another object of the present invention to realize an organic EL display that can be driven with a large current even when a p-channel TFT such as an organic TFT is used.

According to the invention according to claim 1,
A thin film transistor circuit formed on an insulating substrate and having a plurality of pixel circuits arranged in a matrix; a plurality of gate lines and a plurality of source lines connected to the plurality of pixel circuits;
An organic EL layer formed on the substrate;
An organic EL display including at least
The pixel circuit includes at least a first thin film transistor, second and third thin film transistors, a capacitor, and a resistor,
The gate electrode, the source electrode, and the drain electrode of the first thin film transistor are connected to the gate line, the source line, the gate electrode of the second thin film transistor, and one electrode of the capacitor, respectively.
The other electrode of the capacitor is connected to a constant potential;
The second thin film transistor is a p-channel thin film transistor, and a source electrode and a drain electrode of the second thin film transistor are respectively connected to a power supply potential, a gate of the third thin film transistor, and one end of the resistor,
The third thin film transistor is an n-channel thin film transistor, and a drain and a source of the third thin film transistor are connected to the power supply potential, the other end of the resistor, and an anode, respectively.
An organic EL display comprising the organic EL layer between the anode and the cathode is provided.

According to the second aspect of the present invention, the first thin film transistor is a scanning transistor, and the second thin film transistor and the third thin film transistor are driving transistors for driving the organic EL.

According to the third aspect of the present invention, one load transistor may be connected instead of the resistor.

According to the present invention of claim 4, the load transistor may be an n-channel transistor, and the gate and drain of the load transistor may be short-circuited.

According to the fifth aspect of the present invention, the third thin film transistor and the load transistor may have the same semiconductor material, gate insulating layer material and thickness, and channel length.

According to a sixth aspect of the present invention, the second thin film transistor may be a transistor using an organic substance in a semiconductor layer, and the third thin film transistor may be a transistor using an oxide in a semiconductor layer.

According to the seventh aspect of the present invention, the insulating substrate may be made of plastic, and a barrier film that hardly allows oxygen or moisture to pass therethrough may be provided thereon.

According to the eighth aspect of the present invention, the insulating substrate, the gate electrode, the source electrode, the drain electrode, and the gate insulating layer may be transparent.

According to the present invention of claim 9, there is provided an organic EL display manufacturing method of the present invention according to the above-described claims 1 to 8,
Forming a first semiconductor pattern on the insulating substrate;
Forming a first electrode pattern;
Forming a first insulation pattern,
Forming a second electrode pattern,
Forming a second semiconductor pattern;
Forming a second insulation pattern;
Forming a third electrode,
Forming the organic EL layer;
There is provided a method of manufacturing an organic EL display, comprising at least forming the cathode.

According to the tenth aspect of the present invention, the organic EL display according to the first to eighth aspects of the present invention is a method for manufacturing the above-described organic EL display,
Forming a first electrode pattern on the insulating substrate;
Forming a first insulation pattern;
Forming a first semiconductor pattern;
Forming a second electrode pattern,
Forming a second semiconductor pattern;
Forming a second insulation pattern;
Forming a third electrode,
Forming the organic EL layer;
There is provided a method of manufacturing an organic EL display, comprising at least forming the cathode.

According to the present invention of claim 11, a barrier film may be formed in advance on the insulating substrate, and the barrier structure may be formed after the cathode is formed.

According to the present invention of claim 11, the resistor may be formed after the second electrode is formed and before the second insulating layer is formed.

According to the present invention, by combining a p-channel TFT and an n-channel TFT as a driving transistor, both a p-channel type operation and an n-channel-like high performance can be achieved, and a good organic EL display can be realized. Further, according to the present invention, even when a p-channel TFT such as an organic TFT is used, a large current drive can be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit configuration diagram of a pixel circuit constituting a TFT circuit of a pixel portion of an organic EL display of the present invention according to this embodiment. As shown in FIG. 1, the TFT circuit of the pixel portion of the organic EL display according to the present embodiment includes a thin film transistor Tr1, a thin film transistor Tr2, a thin film transistor Tr3, a load resistor R, and a capacitor C in the pixel circuit per pixel. Have. Here, for convenience of explanation, the thin film transistor Tr1 is referred to as a scanning transistor, and the thin film transistors Tr2 and Tr3 are referred to as driving transistors Tr2 and Tr3, respectively. In the organic EL display of the present invention according to this embodiment, as shown in FIG. 1, the drive transistor Tr2 is a p-channel type, and the drive transistor Tr3 is an n-channel type. The scanning transistor Tr1 may be a p-channel type or an n-channel type, but it is desirable that the response is quick. The potential E of the counter electrode of the capacitor C may not be GND as long as it is a constant potential point, and may be Vdd, for example.

In the organic EL display of the present invention according to this embodiment, the gate electrode G1, the source electrode S1, and the drain electrode D1 of the scanning transistor Tr1 are respectively a gate line (scanning line) (Gate) and a source line (data line) ( Source), connected to the gate electrode G2 of the driving transistor Tr2 and one electrode of the capacitor C. The source electrode S2 and the drain electrode D2 of the drive transistor Tr2 are connected to the power supply potential Vdd, one end of the load resistor R, and the gate electrode G3 of the drive transistor Tr3, respectively. The drain electrode D3 and the source electrode S3 of the drive transistor Tr3 are connected to the power supply potential Vdd and the anode (Anode) of the EL layer, respectively. The other end of the load resistor R is connected to the anode (Anode) of the EL layer. The cathode of the EL layer is connected to the common potential Vkk.

In the organic EL display of the present invention according to this embodiment, the gate voltage Vg applied to the gate line (Gate) is applied to the source electrode S1 of the scanning transistor Tr1 through the source line (Source) while the gate voltage Vg is applied to the gate line (Gate). The signal voltage Vs is written into the capacitor C. Then, a current I determined by the voltage (Vdd−Vs) between the source electrode S2 and the gate electrode G2 of the drive transistor Tr2 flows to the drive transistor Tr2. Then, a voltage determined by the current I is generated across the resistor R. Then, flows through the current Id3 is driving transistor Tr3 determined by the voltage, the sum _{I EL} and a current I flowing through the load resistance R flows through the EL layer. The EL layer is driven by this current I _EL . Here, the current I _EL flowing through the EL layer is given by the following formula (1). Here, μ is the mobility of Tr3, L is the channel length of Tr3, W3 is the channel width of Tr3, Cox is the capacitance per unit area of the gate insulating film of Tr3, and Vt is the threshold value of Tr3. If Vt << RI and mutual conductance gm = μWCox (RI−Vt) / L >> 1 / R, then I _EL is proportional to I ² .
μW ₃
I _EL = I + ―――― Cox (RI−V _t ) ² (1)
2L

When a plastic substrate is used to make the organic EL display according to this embodiment a flexible display, when it is not desired to raise the manufacturing process temperature for other reasons, or when it is desired to increase the aperture ratio, an organic compound is used for the p-channel transistor. It is desirable to use a TFT and an oxide TFT for the n-channel transistor. The organic TFT and the oxide TFT have a process temperature required for manufacturing of 200 ° C. or less, and a plastic substrate can be used. In this case, it is desirable to use an n-channel transistor (oxide TFT) having high mobility as the scanning transistor. In addition, since the oxide semiconductor is transparent and has low photoconductivity with visible light, the aperture ratio can be increased by using a transparent material for the substrate, the electrode, and the insulating layer.

As the substrate 1 of the organic EL display according to the present embodiment, glass can be used. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyimide (PI), etc. Plastic materials can also be used. Further, when plastic is used for the substrate, it is desirable to provide a barrier layer for the purpose of protecting the TFT, the organic EL layer and the cathode. The barrier layer is difficult to transmit oxygen and moisture, and an inorganic film such as SiOx, SiON, Al ₂ O ₃ , Y ₂ O ₃ or a laminated structure of an inorganic film and an organic film such as acrylic is used. it can. CVD, vapor deposition, sputtering, or the like can be used to form the barrier layer.

It is desirable to provide a barrier structure after forming the cathode. The barrier structure may be the same as that of the barrier layer, but may be attached with an adhesive around a glass or metal structure. In that case, you may arrange | position a desiccant inside.

In this embodiment, as an oxide semiconductor used for the oxide TFT, an oxide containing any of In, Ga, Zn, Sn, and Mg can be used. Specifically, indium oxide, zinc oxide, tin oxide, ZnMg oxide, InGaZn oxide, In _x Zn _1-x oxide, In _x Sn _1-x oxide, In _x (Zn, Sn) _1-x An oxide, a GaSn oxide, an InGaSn oxide, an InGaZnMg oxide, or the like can be used. These oxide semiconductors can be formed by sputtering, laser ablation, vapor deposition, or the like. In particular, an InGaZn oxide can easily obtain a mobility of 5 cm ² / Vs or more with good reproducibility even when sputtered at any temperature between room temperature and 200 ° C. As an oxide semiconductor used for an oxide TFT Is a suitable material. Further, InGaZnMg oxide has the same mobility as InGaZn oxide, and has a characteristic that it is resistant to ultraviolet rays (is less likely to malfunction) because of its large band gap. Here, although the composition ratio of InGaZn oxide is close to In: Ga: Zn: O = 1: 1: 1: 4, there are actually some oxygen vacancies and a slight metal composition shift. However, the composition ratio is In: Ga: Zn: O = (0.7-1.3) :( 0.7-1.3) :( 0.7-1.3) : (3-4) is allowed. InGaZnMg oxide is basically in an amorphous state, but may partially contain a microcrystalline structure. The InGaZnMg oxide is obtained by replacing a part (for example, 50% or less) of Zn in the InGaZn oxide with magnesium (Mg). When these oxide semiconductors are formed by sputtering, RF or DC reactive sputtering is preferable.

In this embodiment, a polythiophene derivative, a polyphenylene vinylene derivative, a polythienylene vinylene derivative, a polyallylamine derivative, a polyacetylene derivative, an acene derivative, an oligothiophene derivative, or the like can be used as an organic semiconductor used for the organic TFT. These organic semiconductors can be formed by a printing method such as dispenser, ink jet, flexographic printing, or reverse printing, mask vapor deposition, or the like.

In the present embodiment, indium tin oxide (ITO), indium zinc oxide (IZO), or the like is preferably used as an electrode such as a source / drain electrode or a capacitor electrode. If the electrode does not require transparency, a metal such as Al, Ag, Au, Pt, Pd, Ni, Cr, Mo, Ti, or Sn may be used. As the insulating layer, SiO ₂ , SiON, Al ₂ O ₃ , Y ₂ O ₃ or the like is preferably used. These insulating materials can also be formed by sputtering, laser ablation, vapor deposition, or the like at a temperature of room temperature to 200 ° C. In particular, reactive sputtering is preferable. Further, post-annealing may be performed on the insulating layer. The post-annealing temperature may be 200 ° C. or less. It is also possible to use a transparent organic insulating layer for the insulating layer. For example, a fluororesin, polyvinyl alcohol, epoxy, acrylic, or the like can be used for the insulating layer. Patterning is easy with a photosensitive resin. Furthermore, different types of insulating layers may be used in an overlapping manner.

In the organic EL display according to this embodiment, pixel circuits are arranged in a matrix. The upper pixel electrode connected to the source of the driving transistor Tr3 serves as an anode of the EL display, and an organic EL layer is laminated thereon. In the organic EL display according to the present embodiment, a laminated structure such as a hole transport layer 41 and a light emitting layer 42 may be used as the organic EL layer.

In the organic EL display according to the present embodiment, as a material forming the hole transport layer 41, a polyaniline derivative, a polythiophene derivative, a polyvinylcarbazole derivative, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid ( Examples thereof include conductive polymer materials such as PEDOT: PSS). These hole transport materials are dissolved or dispersed in a single or mixed solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, water, and spin coating. It can be applied by a coating method such as bar coating, wire coating or slit coating. Further, patterning may be performed as necessary. Furthermore, you may add surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber etc. to the positive hole transport layer 41 as needed. The thickness of the hole transport layer 41 is preferably in the range of 10 nm to 200 nm. Alternatively, a low molecular material such as TPD (triphenyldiamine) or α-NPD (bis [N-naphthyl-N-phenyl] benzidine) may be used.

In the organic EL display according to the embodiment, the light emitting layer 42 is stacked on the hole transport layer 41. The light emitting layer 42 is not limited to a single layer structure, and may have a multilayer structure in which a charge transport layer or the like is further provided. Examples of the light emitting layer 42 include coumarin, perylene, pyran, anthrone, porphyrin, quinacridone, N, N′-dialkyl substituted quinacridone, naphthalimide, N, N′-diaryl substituted pyrrolopyrrole. Organic light-emitting materials soluble in organic solvents such as iridium complexes, organic light-emitting materials dispersed in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, polyarylenes, polyarylene vinylenes, A polymer fluorescent material such as a polyfluorene-based polymer can be used. These polymeric fluorescent substances are dissolved in a single or mixed solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, water, spin coating method, curtain It can be applied by a coating method such as a coating method, a bar coating method, a wire coating method, or a slit coating method. These polymeric fluorescent substances can also be formed by a printing method. Moreover, you may add surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber etc. to a polymeric fluorescent substance layer as needed. The film thickness of the light emitting layer 42 is preferably 1000 nm or less, and more preferably in the range of 50 nm to 150 nm in combination in either case of a single layer or a multilayer structure. Alternatively, an quinacridone, a coumarin derivative, rubrene, DCM (4- (Dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) derivative, perylene, an iridium complex, or the like is added to an aluminum quinoline complex or a distyryl derivative. Doped low molecular phosphors can be used.

In the low molecular phosphor, the emission color is determined by the material itself and the dopant. In the organic EL display according to the embodiment, as blue light emission, a distylarylene derivative doped with a styrylarylene derivative or a styrylamine derivative, etc., as green light emission, aluminum quinoline complex, etc., as red light emission, DCM is added to aluminum quinoline complex. As a white light emission such as a doped one, a structure in which a blue light emitting material and a yellow to orange light emitting material are laminated is used. On the other hand, in the polymeric fluorescent substance, the emission color can be adjusted by changing the side chain, and a polymer having the same basic skeleton can be used for both RGB. Moreover, white light emission is obtained by mixing them.

In the organic EL display according to the embodiment, when the organic EL layer is an RGB color separation method, it is performed by mask vapor deposition in the case of a low molecular light emitting layer, but it is difficult to perform uniform color separation over a large area. It is. When the polymer light emitting layer is used, a printing method can be used, and uniform coating can be performed over a large area. As a printing method, inkjet, reverse printing, flexographic printing, or the like can be used. In particular, flexographic printing is most preferable because uniform printing over a large area can be performed in a short time. It should be noted that the substrate temperature may be room temperature, whether it is mask vapor deposition or a printing method such as ink jet, reverse printing, flexographic printing or the like. In addition, prior to coating, partition walls may be provided at the coating boundary before forming the hole transport layer 41. As the partition wall, a resist or the like can be used.

In the organic EL display according to the embodiment, as the cathode 5, one according to the light emission characteristics of the organic EL layer can be used. For example, simple metals such as lithium, magnesium, calcium, ytterbium, aluminum, alloys thereof, or these And an alloy with a stable metal such as gold or silver can be used. These materials can be formed by a normal evaporation method such as resistance heating or EB heating. The film thickness is not particularly limited, but a range of 1 nm to 500 nm is preferable. Further, a thin film such as lithium fluoride may be provided between the cathode layer and the light emitting layer.

Next, the manufacturing method of the organic EL display of the present invention according to this embodiment will be described in detail. 2 is a plan view (FIG. 2 (a)) and a cross-sectional view (FIG. 2 (b)) of the pixel circuit (TFT circuit) of the organic EL display according to the present embodiment shown in FIG. The process is shown in FIGS. 3A and 3B. 3A and 3B, FIGS. 3A to 3I are cross-sectional views for one pixel circuit (one subpixel), and FIGS. 3J to 3L are pixel circuits 6. FIG. 3 (m) shows a cross-sectional view of the entire EL display of the present invention according to this embodiment.

First, the barrier film 11 is formed on the substrate 1 (FIG. 3A). Next, an oxide semiconductor is formed by reactive sputtering or the like as the first semiconductor layer 21 serving as a semiconductor layer of Tr1 and Tr3, and is patterned using a photolithography technique (FIG. 3B). Then, ITO is formed by reactive sputtering or the like as the first electrode layer 22 including the source electrode (S1), the drain electrode (D1) / gate electrode (G2), the source electrode (S3), and the drain electrode (D3). Patterning is performed using a photolithographic technique (FIG. 3C).

Next, a first insulating layer 23 to be a gate insulating layer is formed by reactive sputtering or the like, and is patterned using a photolithography technique (FIG. 3D). Furthermore, ITO is formed by reactive sputtering or the like as the second electrode layer 24 including the gate electrode (G1), the capacitor (C) electrode, the source electrode (S2), the drain electrode (D2) and the gate electrode (G3), Patterning is performed using photolithography technology (FIG. 3E). Then, the resistor 3 is formed by a method such as screen printing of a resistance paste (FIG. 3F). Further, a second semiconductor layer 25 to be a semiconductor layer of Tr2 is formed with a dispenser or the like (FIG. 3G). Next, a second insulating layer 26 to be an interlayer insulating film is formed and patterned (FIG. 3H). Further, a third electrode layer 27 to be a pixel electrode is formed and patterned (FIG. 3 (i)).

Then, the organic EL layer 4 is formed. First, the hole transport layer 41 is applied to the entire surface (FIG. 3 (j)). Next, the light emitting layers 42R, 42G, and 42B are formed by flexographic printing or the like (FIG. 3 (k)).

Further, the cathode 5 is formed on the entire surface by vapor deposition (FIG. 3L). Finally, it is desirable to form the barrier structure 6 by a method such as covering the whole with a glass plate or a metal plate, or forming a sealing layer (FIG. 3M). The glass plate and the metal plate can be sealed with an adhesive such as epoxy, and a desiccant may be put in the gap between the sample and the glass plate or metal plate.

(Embodiment 2) In Embodiment 2, an organic EL display of the present invention having a pixel circuit configuration different from that of Embodiment 1 will be described. In addition, about the structure similar to the organic electroluminescent display of this invention which concerns on Embodiment 1, it may not demonstrate anew here.

FIG. 4 is a circuit configuration diagram of a pixel circuit constituting the TFT circuit of the pixel portion of the organic EL display according to the present embodiment. As shown in FIG. 4, the TFT circuit of the pixel portion of the organic EL display according to the present embodiment includes a thin film transistor Tr1, a thin film transistor Tr2, a thin film transistor Tr3, a thin film transistor Tr4, and a capacitor C in the pixel circuit per pixel. is doing. Here, for convenience of explanation, as in the first embodiment, the thin film transistor Tr1 is referred to as a scanning transistor, and the thin film transistors Tr2 and Tr3 are referred to as drive transistors Tr2 and Tr3, respectively. The thin film transistor Tr4 is referred to as a load transistor. In the organic EL display of the present invention according to this embodiment, as shown in FIG. 4, the drive transistor Tr2 is a p-channel type, the drive transistor Tr3 is an n-channel type, and the load transistor Tr4 is an n-channel type transistor. . The scanning transistor Tr1 may be a p-channel type or an n-channel type, but it is desirable that the response is quick. The potential (E) of the counter electrode of the capacitor C may not be GND as long as it is a constant potential point, and may be, for example, Vdd.

In the organic EL display of the present invention according to this embodiment, the gate electrode G1, the source electrode S1, and the drain electrode D1 of the scanning transistor Tr1 are respectively a gate line (scanning line) (Gate) and a source line (data line) ( Source), connected to the gate electrode G2 of the driving transistor Tr2 and one electrode of the capacitor C. The source electrode S2 and the drain electrode D2 of the drive transistor Tr2 are connected to the power supply potential Vdd, the gate electrode G4 and the drain electrode D4 of the load transistor Tr4, and the gate electrode G3 of the drive transistor Tr3, respectively. The drain electrode D3 and the source electrode S3 of the drive transistor Tr3 are connected to the power supply potential Vdd and the anode (Anode) of the EL layer, respectively. The source electrode of the load transistor Tr4 is connected to the anode (Anode) of the EL layer. The cathode of the EL layer is connected to a common potential (Vkk).

In the organic EL display of the present invention according to this embodiment, the gate voltage Vg applied to the gate line (Gate) is applied to the source S1 of the scanning transistor Tr1 through the source line (Source) with a predetermined voltage Vg applied to the gate line (Gate). When the selection potential is set, the signal voltage Vs is written into the capacitor C. Then, a current I determined by the voltage (Vdd−Vs) between the source electrode S2 and the gate electrode G2 of the drive transistor Tr2 flows to the drive transistor Tr2. Then, a voltage generated by the current I is generated at both ends of the load transistor Tr4. A current determined by the voltage flows through the drive transistor Tr3, and a sum I _EL with the current flowing through the drive transistor Tr4 flows through the EL layer. The EL layer is driven by this current I _EL . Here, the current flowing through the EL layer is given by the following formula (2). Here, μ is the mobility of Tr3 and Tr4, L is the channel length of Tr3 and Tr4, W3 is the channel width of Tr3, W4 is the channel width of Tr4, Cox is the capacitance per unit area of the gate insulating film of Tr3 and Tr4 , Vt are the threshold values of Tr3 and Tr4. If the semiconductor material and thickness of Tr3 and Tr4, the material and thickness of the gate insulating layer, and the channel length are the same, μ, L, Cox, and Vt can be regarded as equal. In this case, if Vt is small, I _EL is proportional to I. The proportionality coefficient can be determined only by the channel width and is easy to design.


W ₃ + W ₄ μW ₃
I _EL = ―――――― I + ――― CoxV _t ² (2)
W ₄ 2L

As in Embodiment 1, when using a plastic substrate to make the organic EL display according to Embodiment 2 flexible, if you do not want to increase the manufacturing process temperature for other reasons, or if you want to increase the aperture ratio It is desirable to use an organic TFT for the p-channel transistor and an oxide TFT for the n-channel transistor. The organic TFT and the oxide TFT have a process temperature required for manufacturing of 200 ° C. or less, and a plastic substrate can be used. In this case, it is desirable to use an n-channel transistor (oxide TFT) having high mobility as the scanning transistor. In addition, since the oxide semiconductor is transparent and has low photoconductivity with visible light, the aperture ratio can be increased by using a transparent material for the substrate, the electrode, and the insulating layer.

Further, as the substrate 1 of the organic EL display according to the present embodiment, the same one as described in the first embodiment can be used.

In the organic EL display according to the present embodiment, it is desirable to provide a barrier structure after forming the cathode, as in the first embodiment. The barrier structure may be the same as that of the barrier layer, but may be attached with an adhesive around a glass or metal structure. In that case, you may arrange | position a desiccant inside.

Also in the organic EL display according to the present embodiment, an oxide TFT and an organic TFT can be used as in the first embodiment. The oxide TFT and organic TFT used in this embodiment can be the same as those in Embodiment 1.

In addition, as an electrode such as a source / drain electrode and a capacitor electrode and an insulating film in this embodiment, the same materials as those in Embodiment 1 can be used.

In the organic EL display according to the present embodiment, pixel circuits are arranged in a matrix as in the first embodiment. The upper pixel electrode connected to the source of the driving transistor Tr3 serves as an anode of the EL display, and an organic EL layer is laminated thereon. In the organic EL display according to the present embodiment, as in the first embodiment, a stacked structure of the hole transport layer 41, the light emitting layer 42, and the like may be used as the organic EL layer. In the second embodiment, the same hole transport layer 41 and light emitting layer 42 as those in the first embodiment can be used.

In the organic EL display according to the embodiment, as the cathode 5, one according to the light emission characteristics of the organic EL layer can be used, and the same one as in the first embodiment can be used. Further, a thin film such as lithium fluoride may be provided between the cathode layer and the light emitting layer.

Next, an example of the manufacturing method of the organic EL display of the present invention according to Embodiment 2 will be described in detail. FIG. 5 is a plan view (FIG. 5A) and a cross-sectional view (FIG. 5B) of the pixel circuit (TFT circuit) of the organic EL display according to the present embodiment shown in FIG. The process is shown in FIGS. 6A and 6B. FIG. 5 shows that the gate electrode (G3) of the drive transistor Tr3 and the gate electrode (G4) of the load transistor Tr4 are connected at a portion other than the cross-sectional view. 6A and 6B, FIGS. 6A to 6H are cross-sectional views for one pixel circuit (one subpixel), and FIGS. 6I to 6K are pixel circuits 6. FIG. 6 (l) shows a cross-sectional view of the entire EL display of the present invention according to this embodiment.

First, the barrier film 11 is formed on the substrate 1 (FIG. 6A). Next, an oxide semiconductor is formed by reactive sputtering or the like as the first semiconductor layer 21 serving as a semiconductor layer of Tr1 and Tr3, and is patterned using a photolithography technique (FIG. 6B). The first electrode layer 22 including the source electrode (S1), the drain electrode (D1) / gate electrode (G2), the source electrode (S3) / source electrode (S4), the drain electrode (D3), and the drain electrode (D4). As shown in FIG. 6C, ITO is formed by reactive sputtering or the like, and is patterned using a photolithography technique (FIG. 6C).

Next, a first insulating layer 23 to be a gate insulating layer is formed by reactive sputtering or the like, and is patterned using a photolithography technique (FIG. 6D). Further, ITO is reactively sputtered as the second electrode layer 24 including the gate electrode (G1), the capacitor electrode (C), the source electrode (S2), the drain electrode (D2), the gate electrode (G3), and the gate electrode (G4). Then, a film is formed by patterning using photolithography (FIG. 6E). Further, a second semiconductor layer 25 to be a semiconductor layer of Tr2 is formed with a dispenser or the like (FIG. 6F). Next, a second insulating layer 26 to be an interlayer insulating film is formed and patterned (FIG. 6G). Further, a third electrode layer 27 to be a pixel electrode is formed and patterned (FIG. 6H).

Then, the organic EL layer 4 is formed. First, the hole transport layer 41 is applied to the entire surface (FIG. 6 (i)). Next, the light emitting layers 42R, 42G, and 42B are formed by flexographic printing or the like (FIG. 6 (j)).

Further, the cathode 5 is formed on the entire surface by vapor deposition (FIG. 6 (k)). Finally, it is desirable to provide the barrier structure 6 by a method such as covering the whole with a glass plate or a metal plate, or forming a sealing layer (FIG. 6L). The glass plate and the metal plate can be sealed with an adhesive such as epoxy, and a desiccant may be put in the gap between the sample and the glass plate or metal plate.

(Embodiment 3) The circuit configuration of the pixel circuit (TFT circuit) of the organic EL display of the present invention according to Embodiment 3 is the circuit configuration of the pixel circuit (TFT circuit) of the organic EL display of the present invention according to Embodiment 1. It is the same. In the third embodiment, an organic EL display having a device structure different from the device structure of the pixel circuit of the organic EL display according to the first embodiment will be described. In the third embodiment, the same configuration as that of the first embodiment may not be described again in order to avoid redundant description including materials used.

FIG. 7 is a plan view (FIG. 7A) and a cross-sectional view (FIG. 7B) of a pixel circuit (TFT circuit) of the organic EL display of the present invention according to this embodiment. It is shown in 8A and FIG. 8B. 8A and 8B, FIGS. 8A to 8I are cross-sectional views for one pixel circuit (one subpixel), and FIGS. 8J to 8L are pixel circuits 6. FIG. 8 (m) shows an overall cross-sectional view of the EL display of the present invention according to this embodiment.

First, the barrier film 11 is formed on the substrate 1 (FIG. 8A). Next, ITO is formed by reactive sputtering or the like as the first electrode layer 22 including the gate electrodes G1, G2, and G3 and the capacitor electrode C, and is patterned using a photolithography technique (FIG. 8B). And the 1st insulating layer 23 used as a gate insulating layer is formed into a film by reactive sputtering, and is patterned using the photolithographic technique (FIG.8 (c)).

Next, an oxide semiconductor is formed by reactive sputtering or the like as the first semiconductor layer 21 serving as the semiconductor layers of Tr1 and Tr3, and is patterned using a photolithography technique (FIG. 8D). Then, ITO is formed by reactive sputtering or the like as the second electrode layer 24 including the source electrodes (S1, S2, S3) and the drain electrodes (D1, D2, D3), and is patterned using a photolithography technique (FIG. 8). (E)). Then, the resistor 3 is formed by a method such as screen printing of a resistance paste (FIG. 8F). Further, a second semiconductor layer 25 to be a semiconductor layer of Tr2 is formed with a dispenser or the like (FIG. 8G). Next, a second insulating layer 26 to be an interlayer insulating film is formed and patterned (FIG. 8H). Further, a third electrode layer 27 to be a pixel electrode is formed and patterned (FIG. 8 (i)).

Then, the organic EL layer 4 is formed. First, the hole transport layer 41 is applied to the entire surface (FIG. 8 (j)). Next, light emitting layers 42R, 42G, and 42B are formed by flexographic printing or the like (FIG. 8 (k)).

Further, the cathode 5 is formed on the entire surface by vapor deposition (FIG. 8L). Finally, it is desirable to provide a barrier structure by a method such as covering the whole with a glass plate or a metal plate, or forming a sealing layer (FIG. 8 (m)). The glass plate and the metal plate can be sealed with an adhesive such as epoxy, and a desiccant may be put in the gap between the sample and the glass plate or metal plate.

(Embodiment 4) The circuit configuration of the pixel circuit (TFT circuit) of the organic EL display of the present invention according to Embodiment 4 is the circuit configuration of the pixel circuit (TFT circuit) of the organic EL display of the present invention according to Embodiment 2. It is the same. In the fourth embodiment, an organic EL display having a device structure different from the device structure of the pixel circuit of the organic EL display according to the second embodiment will be described. In the fourth embodiment, the same configuration as that of the second embodiment may not be described again in order to avoid redundant description including materials used.

FIG. 9 is a plan view (FIG. 9A) and a cross-sectional view (FIG. 9B) of a pixel circuit (TFT circuit) of the organic EL display of the present invention according to the present embodiment, and the manufacturing process thereof is illustrated. 10A and 10B. In FIG. 9, the source (S2) of the driving transistor Tr2 and the drain (D3) of the driving transistor Tr3 are connected at a portion other than the cross-sectional view, and the drain (D2) of the driving transistor Tr2 and the drain (D4) of the load transistor Tr4 ) Indicates connection at a portion other than the cross-sectional view. 10A and 10B, FIGS. 10A to 10H are cross-sectional views for one pixel circuit (one subpixel), and FIGS. 10I to 10K are pixel circuits 6. FIG. 10 (l) shows an overall cross-sectional view of the EL display of the present invention according to this embodiment.

First, the barrier film 11 is formed on the substrate 1 (FIG. 10A). Next, ITO is deposited by reactive sputtering or the like as the first electrode layer 22 to be the gate electrodes G1, G2, G3 and G4, and is patterned using a photolithography technique (FIG. 10B). Then, a first insulating layer 23 to be a gate insulating layer is formed by reactive sputtering or the like, and is patterned using a photolithography technique (FIG. 10C).

Next, an oxide semiconductor is formed by reactive sputtering or the like as the first semiconductor layer 21 serving as a semiconductor layer of Tr1, Tr3, and Tr4, and is patterned using a photolithographic technique (FIG. 10D). Then, ITO is formed by reactive sputtering or the like as the second electrode layer 24 to be the source / drain electrodes (S1, S2 and D3, S3 and S4, D1, and D2 and D4), and is patterned using a photolithography technique ( FIG. 10 (e)). Further, a second semiconductor layer 25 to be a semiconductor layer of Tr2 is formed with a dispenser or the like (FIG. 10F). Next, a second insulating layer 26 to be an interlayer insulating film is formed and patterned (FIG. 10G). Further, a third electrode layer 27 to be a pixel electrode is formed and patterned (FIG. 10H).

Then, the organic EL layer 4 is formed. First, the hole transport layer 41 is applied to the entire surface (FIG. 10 (i)). Next, the light emitting layers 42R, 42G, and 42B are formed by flexographic printing or the like (FIG. 10 (j)).

Further, the cathode 5 is formed on the entire surface by vapor deposition (FIG. 10 (k)). Finally, it is desirable to provide a barrier structure by a method such as covering the whole with a glass plate or a metal plate, or forming a sealing layer (FIG. 10L). The glass plate or the metal plate can be sealed with an adhesive such as epoxy, and a desiccant may be put in the gap between the sample and the glass plate or the metal plate.

In addition, although the example which used ITO as the 1st electrode layer 22 and the 2nd electrode layer 24 was shown here, as demonstrated in Embodiment 1, electrode material may not be ITO. For example, a transparent conductive film such as IZO or ATO can be used, and a metal such as Al, Ag, or Au can be used in consideration of a decrease in the aperture ratio. Alternatively, for example, there is a method in which only the organic TFT is shielded by using a metal only for the gate electrode (G2) of the drive transistor Tr2. Further, a separate light shielding film can be formed only on the organic TFT portion. Further, a sealing layer (for preventing semiconductor deterioration) may be provided in contact with the organic semiconductor or the oxide semiconductor. The sealing layer and the light shielding layer may be the same layer.

Hereinafter, specific examples of the organic EL display of the present invention according to the above-described first to fourth embodiments will be described in detail using examples. <Example 1> In Example 1, a specific mode of the organic EL display of the present invention according to Embodiment 1 described above will be described.

PEN was used as the substrate 1, and SiO ₂ was deposited thereon as a barrier layer 11 by 100 nm CVD (FIG. 3A). Next, an InGaZn oxide is formed as the first semiconductor layer 21 to be a semiconductor layer of Tr1 and Tr3, and a film is formed by reactive sputtering (room temperature, RF sputtering) under Ar + O ₂ gas using InGaZnO ₄ as a target, and a photoresist is applied. Patterning was performed by exposure, development, wet etching with hydrochloric acid, and resist stripping (FIG. 3B). Further, after forming a photoresist pattern in advance, ITO is used as the first electrode layer 22 including the source electrode S1, the drain electrode D1 and gate electrode G2, the source electrode S3, and the drain electrode D3, and the reactivity under Ar + O ₂ gas using ITO as a target. A film was formed by sputtering (room temperature, DC sputtering) and patterned by lift-off (FIG. 3C). Then, after the photoresist pattern is formed in advance, SiON is formed as the first insulating layer 23, SiN is used as a target, and reactive sputtering (room temperature, RF sputtering) is performed under Ar + O ₂ + N ₂ gas, followed by patterning by lift-off (FIG. 3 (d)). Further, ITO is used as the second electrode layer 24 including the gate electrode G1, the capacitor electrode C, the source electrode S2, the drain electrode D2 and the gate electrode G3 after the photoresist pattern is formed in advance, and the same reactivity as the first electrode layer 32 is obtained. A film was formed by sputtering and patterned by lift-off (FIG. 3E).

And the resistor 3 was formed by screen-printing and baking the carbon-type resistor paste (FIG.3 (f)). Next, a thiophene-based material was dispensed and fired as the second semiconductor layer 25 (FIG. 3G). Here, a fluorine-based black resin is screen-printed (not shown) as a sealing and light-shielding layer so as to cover the second semiconductor layer 25, and a photosensitive acrylic resin is further applied as a second insulating layer 26 by coating / exposure / development. Patterning is performed (FIG. 3 (h)), ITO is formed as the third electrode layer 27 by reactive sputtering similar to the first electrode layer 22, photoresist coating, exposure, development, wet etching with hydrochloric acid, resist Patterning was performed by peeling (FIG. 3 (i)).

And the organic EL layer 4 was formed. First, a PEDOT: PSS solution was spin-coated on the entire surface as a hole transport layer 41 and baked at 100 ° C. (FIG. 3J). Next, polyfluorene-based materials were sequentially formed as the red light emitting layer 42R, the green light emitting layer 42G, and the blue light emitting layer 42B by flexographic printing (FIG. 3 (k)).

Further, the cathode 5 was formed as a cathode 5 by vapor deposition to form a film of 10 nm of calcium and 300 nm of silver on the entire surface (FIG. 3 (l)). Finally, a SiO ₂ / acrylic / SiO ₂ laminated film was deposited as a barrier structure 6 on the whole (FIG. 3 (m)).

The organic EL display of the present invention according to this example produced in this way was flexible, light, thin, did not break even when bent slightly, and did not break even when dropped from a height of 1 m. In addition, when viewed from the substrate side, the aperture ratio was large and bright display was achieved.

<Example 2> In Example 2, a specific mode of the organic EL display of the present invention according to Embodiment 2 described above will be described.

Glass was used as the substrate 1, and SiO ₂ was deposited thereon as a buffer layer 12 by 100 nm CVD (FIG. 6A). Next, an InGaZn oxide is formed as the first semiconductor layer 21 to be a semiconductor layer of Tr1 and Tr3, and a film is formed by reactive sputtering (room temperature, RF sputtering) under Ar + O ₂ gas using InGaZnO ₄ as a target, and a photoresist is applied. Patterning was performed by exposure, development, wet etching with hydrochloric acid, and resist stripping (FIG. 6B). Further, after forming a photoresist pattern in advance, ITO is used as the first electrode layer 22 including the source electrode S1, the drain electrode D1 and gate electrode G2, the source electrode S3 and source electrode S4, the drain electrode D3, and the drain electrode D4, and ITO is used as a target. A film was formed by reactive sputtering (room temperature, DC sputtering) under Ar + O 2 gas and patterned by lift-off (FIG. 6C). Then, after forming a photoresist pattern in advance, SiON is formed as the first insulating layer 23, SiN is used as a target, and reactive sputtering (room temperature, RF sputtering) is performed under Ar + O ₂ + N ₂ gas, followed by patterning by lift-off (FIG. 6). (D)). Further, after the photoresist pattern is formed in advance, ITO is used as the second electrode layer 24 including the gate electrode G1, the capacitor electrode C, the source electrode S2, the drain electrode D2 and the gate electrode G3 and the gate electrode G4. A film was formed by reactive sputtering and patterned by lift-off (FIG. 6E).

Next, a thiophene-based material was dispensed and fired as the second semiconductor layer 25 (FIG. 6F). Here, a fluorine black resin is screen-printed (not shown) as the sealing and light shielding layer 28 so as to cover the second semiconductor layer 25, and a photosensitive acrylic resin is applied, exposed and developed as the second insulating layer 26. (FIG. 6 (g)), ITO as the third electrode layer 27 is formed by reactive sputtering similar to the first electrode layer 22, photoresist coating, exposure, development, wet etching with hydrochloric acid, Patterning was performed by resist stripping (FIG. 6H).

And the organic EL layer 4 was formed. First, a PEDOT: PSS solution was spin-coated on the entire surface as the hole transport layer 41 and baked at 100 ° C. (FIG. 6 (i)). Next, polyfluorene-based materials were sequentially formed as a red light emitting layer 42R, a green light emitting layer 42G, and a blue light emitting layer 42B by flexographic printing (FIG. 6 (j)).

Further, the cathode 5 was formed as a cathode 5 by vapor deposition to form a film of 10 nm of calcium and 300 nm of silver on the entire surface (FIG. 6 (k)). Finally, glass was attached as an overall barrier structure 6 with an adhesive (FIG. 6 (l)).

The organic EL display of the present invention according to the present example produced in this way had a large aperture ratio and a bright display when viewed from the substrate side. In addition, good display with small luminance unevenness was achieved.

<Example 3> In Example 3, a specific mode of the organic EL display of the present invention according to Embodiment 3 described above will be described.

PEN was used as the substrate 1, and SiO ₂ was deposited thereon as a barrier layer 11 by 100 nm CVD (FIG. 8A). Next, ITO is formed as the first electrode layer 22 including the gate electrodes G1, G2, G3 and the capacitor electrode C, and the film is formed by reactive sputtering (room temperature, DC sputtering) under Ar + O2 gas using ITO as a target. Patterning was performed by coating, exposure, development, wet etching with hydrochloric acid, and resist stripping (FIG. 8B). Further, after forming a photoresist pattern in advance, SiON is formed as a first insulating layer 23, SiN is used as a target, and reactive sputtering (room temperature, RF sputtering) is performed under Ar + O ₂ + N ₂ gas, followed by patterning by lift-off (FIG. 8 (c)). Then, after the photoresist pattern is formed in advance, a film is formed by reactive sputtering (room temperature, RF sputtering) under the Ar + O ₂ gas using InGaZnO ₄ as a target and the first semiconductor layer 21 serving as the Tr1 and Tr3 semiconductor layers. Then, patterning was performed by lift-off (FIG. 8D). Furthermore, after the photoresist pattern is formed in advance, ITO is deposited by reactive sputtering similar to the first electrode layer 22 as the second electrode layer 24 including the source electrodes S1, S2, S3, the drain electrodes D1, D2, D3, Patterning was performed by lift-off (FIG. 8E).

And the resistor 3 was formed by screen-printing and baking the carbon-type resistor paste (FIG.8 (f)). Next, a thiophene-based material was dispensed and fired as the second semiconductor layer 25 (FIG. 8G). Here, a fluorine black resin is screen-printed (not shown) as the sealing and light shielding layer 28 so as to cover the first semiconductor layer 21 and the second semiconductor layer 25, and a photosensitive acrylic resin is further used as the second insulating layer 26. Is patterned by coating / exposure / development (FIG. 8H), ITO is formed as the third electrode layer 27 by reactive sputtering similar to the first electrode layer 22, and photoresist coating / exposure / development is performed. Patterning was performed by wet etching with hydrochloric acid and resist peeling (FIG. 8 (i)).

And the organic EL layer 4 was formed. First, a PEDOT: PSS solution was spin-coated on the entire surface as the hole transport layer 41 and baked at 100 ° C. (FIG. 8J). Next, polyfluorene-based materials were sequentially formed as a red light emitting layer 42R, a green light emitting layer 42G, and a blue light emitting layer 42B by flexographic printing (FIG. 8 (k)).

Furthermore, a film of 10 nm calcium and 300 nm silver was formed as the cathode 5 by vapor deposition on the entire surface (FIG. 8 (l)). Finally, a SiO ₂ / acrylic / SiO ₂ laminated film was deposited as a barrier structure 6 on the whole (FIG. 8 (m)).

The organic EL display of the present invention according to this example produced in this way was flexible, light, thin, did not break even when bent slightly, and did not break even when dropped from a height of 1 m. In addition, when viewed from the substrate side, the aperture ratio was large and bright display was achieved.

Example 4 In Example 4, a specific mode of the organic EL display according to the third embodiment of the present invention will be described.

Glass was used as the substrate 1, and SiO ₂ was deposited thereon as a buffer layer 12 by 100 nm CVD (FIG. 10A). Next, ITO is formed as the first electrode layer 22 including the gate electrodes G1, G2, G3 and G4 by reactive sputtering (room temperature, RF sputtering) under Ar + O2 gas using ITO as a target, and resist coating / exposure is performed. Patterning was performed by development, wet etching with hydrochloric acid, and resist stripping (FIG. 10B). Further, after a photoresist pattern is formed in advance, SiON is formed as the first insulating layer 23, and SiN is used as a target by reactive sputtering (room temperature, RF sputtering) under Ar + O2 + N2 gas, followed by patterning by lift-off (FIG. 10C). ). Then, after forming a photoresist pattern in advance, the first semiconductor layer 21 serving as a semiconductor layer of Tr1, Tr3, and Tr4 is formed by reactive sputtering (room temperature, RF sputtering) using InGaZnO4 as a target and ArGa02O4 as a target under Ar + O2 gas. A film was formed and patterned by lift-off (FIG. 10D). Furthermore, ITO is used as the second electrode layer 24 including the source / drain electrodes S1, S2 and D3, S3 and S4, D1 and D2 and D4 after the photoresist pattern is formed in advance, by reactive sputtering similar to the first electrode layer 22. A film was formed and patterned by lift-off (FIG. 10E).

Next, a thiophene-based material was dispensed and fired as the second semiconductor layer 25 (FIG. 10F). Here, a fluorine black resin is screen-printed (not shown) as the sealing and light shielding layer 28 so as to cover the first semiconductor layer 21 and the second semiconductor layer 25, and a photosensitive acrylic resin is further used as the second insulating layer 26. Is patterned by coating / exposure / development (FIG. 10G), ITO is formed as the third electrode layer 27 by reactive sputtering similar to the first electrode layer 32, and photoresist coating / exposure / development is performed. Patterning was performed by wet etching with hydrochloric acid and resist peeling (FIG. 10 (h)).

And the organic EL layer 4 was formed. First, a PEDOT: PSS solution was spin-coated on the entire surface as a hole transport layer 41 and baked at 100 ° C. (FIG. 10I). Next, polyfluorene-based materials were sequentially formed as the red light emitting layer 42R, the green light emitting layer 42G, and the blue light emitting layer 42B by flexographic printing (FIG. 10 (j)).

Further, the cathode 5 was formed as a cathode 5 by vapor deposition on the entire surface with 10 nm of calcium and 300 nm of silver (FIG. 10 (k)). Finally, glass was attached as an overall barrier structure 6 with an adhesive (FIG. 10 (l)).

The organic EL display of the present invention according to the present example produced in this way had a large aperture ratio and a bright display when viewed from the substrate side. In addition, good display with small luminance unevenness was achieved.

FIG. 3 is a circuit configuration diagram of a pixel circuit of an EL display according to the first and third embodiments of the present invention. They are a cross-sectional schematic diagram (FIG. 2 (a)) and a top view (FIG.2 (b)) which show an example of the structure of the EL display of this invention which concerns on Embodiment 1. FIG. 5 is a cross-sectional view showing an example of a manufacturing process of the EL display of the present invention according to Embodiment 1. FIG. 5 is a cross-sectional view showing an example of a manufacturing process of the EL display of the present invention according to Embodiment 1. FIG. FIG. 5 is a circuit configuration diagram of a pixel circuit of an EL display according to the second and fourth embodiments of the present invention. It is the cross-sectional schematic diagram (FIG. 5 (a)) and the top view (FIG.5 (b)) which show an example of the structure of the EL display of this invention which concerns on Embodiment 2. FIG. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 2. FIG. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 2. FIG. It is the cross-sectional schematic diagram (FIG.7 (a)) and top view (FIG.7 (b)) which show an example of the structure of the EL display of this invention which concerns on Embodiment 3. FIG. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 3. FIG. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 3. FIG. FIG. 9 is a schematic cross-sectional view (FIG. 9A) and a plan view (FIG. 9B) showing an example of the structure of an EL display according to Embodiment 4 of the present invention. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 4. FIG. It is sectional drawing which shows an example of the manufacturing process of EL display of this invention which concerns on Embodiment 4. FIG. It is a circuit block diagram of the pixel circuit of the conventional EL display.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent substrate 11 Barrier layer 12 Buffer layer 2 TFT circuit 21 First semiconductor layer 22 First electrode layer 23 First insulating layer 24 Second electrode layer 25 Second semiconductor layer 26 Second insulating layer 27 Third electrode layer 28 Sealing Layer and light shielding layer 3 Resistors G1 to G4 Gate electrodes S1 to S4 Source electrodes D1 to D4 Drain electrode C Capacitor electrode R Resistor 4 Organic EL layer 41 Hole transport layer 42 Light emitting layer 42R Red light emitting layer 42G Green light emitting layer 42B Blue Light emitting layer 5 Cathode 6 Barrier structure

Claims (12)

A thin film transistor circuit formed on an insulating substrate and having a plurality of pixel circuits arranged in a matrix; a plurality of gate lines and a plurality of source lines connected to the plurality of pixel circuits;
An organic EL layer formed on the substrate;
An organic EL display including at least
The pixel circuit includes at least a first thin film transistor, second and third thin film transistors, a capacitor, and a resistor,
The gate electrode, the source electrode, and the drain electrode of the first thin film transistor are connected to the gate line, the source line, the gate electrode of the second thin film transistor, and one electrode of the capacitor, respectively.
The other electrode of the capacitor is connected to a constant potential;
The second thin film transistor is a p-channel thin film transistor, and a source electrode and a drain electrode of the second thin film transistor are respectively connected to a power supply potential, a gate of the third thin film transistor, and one end of the resistor.
The third thin film transistor is an n-channel thin film transistor, and a drain and a source of the third thin film transistor are connected to the power supply potential, the other end of the resistor, and an anode, respectively.
An organic EL display comprising the organic EL layer between the anode and the cathode. 2. The organic EL display according to claim 1, wherein the first thin film transistor is a scanning transistor, and the second thin film transistor and the third thin film transistor are driving transistors for driving the organic EL. . 3. The organic EL display according to claim 1, wherein one load transistor is connected instead of the resistor. 4. The organic EL display according to claim 3, wherein the load transistor is an n-channel transistor, and a gate and a drain of the load transistor are short-circuited. 5. The organic EL display according to claim 3, wherein the semiconductor material of the third thin film transistor and the load transistor, the material and thickness of the gate insulating layer, and the channel length are the same. The second thin film transistor is a transistor using an organic substance in a semiconductor layer, and the third thin film transistor is a transistor using an oxide in a semiconductor layer. Organic EL display. The organic EL display according to claim 1, wherein the insulating substrate is made of plastic, and a barrier film that hardly allows oxygen and moisture to pass therethrough is provided thereon. The organic EL display according to claim 1, wherein the insulating substrate, the gate electrode, the source electrode, the drain electrode, and the gate insulating layer are transparent. It is a manufacturing method of the organic EL display according to any one of claims 1 to 8,
Forming a first semiconductor pattern on the insulating substrate;
Forming a first electrode pattern;
Forming a first insulation pattern;
Forming a second electrode pattern,
Forming a second semiconductor pattern;
Forming a second insulation pattern;
Forming a third electrode,
Forming the organic EL layer;
A method for producing an organic EL display, comprising at least forming the cathode. It is a manufacturing method of the organic EL display according to any one of claims 1 to 8,
Forming a first electrode pattern on the insulating substrate;
Forming a first insulation pattern;
Forming a first semiconductor pattern;
Forming a second electrode pattern,
Forming a second semiconductor pattern;
Forming a second insulation pattern;
Forming a third electrode,
Forming the organic EL layer;
A method for producing an organic EL display, comprising at least forming the cathode. 11. The method of manufacturing an organic EL display according to claim 9, further comprising: forming a barrier film on the insulating substrate in advance and forming a barrier structure after forming the cathode. The organic EL display according to claim 9, wherein the resistor is formed after the second electrode is formed and before the second insulating layer is formed. Manufacturing method.