JP2009031750A - Organic EL display device and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide an organic EL display device in which a TFT for driving the organic EL element is disposed on the organic EL element, and a method for manufacturing the same. In particular, an active organic EL display device having a high aperture ratio, high definition, high brightness, high stability, high reliability, and a long lifetime and a method for manufacturing the same are provided.
An organic EL display device having an organic EL element having at least a lower electrode, an organic layer including at least a light emitting layer, and an upper electrode in order on a substrate, wherein at least a gate electrode and a gate insulating film are formed on the upper electrode. An organic EL display device comprising: an active layer; a source electrode; a drain electrode; and a TFT for driving the organic EL element, wherein the active layer contains an oxide semiconductor.
[Selection figure] None

Description

The present invention relates to an organic EL display device in which a thin film field effect transistor for driving the organic EL element is disposed on the organic EL element, and a method for manufacturing the same. In particular, the present invention relates to an active organic EL display device having a high aperture ratio, high definition, high brightness, high stability, high reliability, and a long lifetime, and a method for manufacturing the same.
About.

2. Description of the Related Art In recent years, flat and thin image display devices (Flat Panel Displays: FPD) have been put into practical use due to advances in liquid crystal and electroluminescence (EL) technologies. In particular, an organic electroluminescent device using a thin film material that emits light when excited by passing an electric current (hereinafter sometimes referred to as “organic EL device”) can emit light with high luminance at a low voltage. Device thinning, lightening, miniaturization, and power saving are expected in a wide range of fields including mobile phone displays, personal digital assistants (PDAs), computer displays, automobile information displays, TV monitors, or general lighting. ing.
These FPDs are active field-effect thin film transistors (hereinafter referred to as “Thin Film Transistor” or “TFT”) that use an amorphous silicon thin film or a polycrystalline silicon thin film provided on a glass substrate as an active layer. It is driven by a matrix circuit.

On the other hand, in order to achieve further high definition, high brightness, and long life of these active organic EL display devices, it is known that a top emission method capable of obtaining a high aperture ratio is advantageous. However, it is difficult to form a transparent conductive film such as ITO directly on the organic layer without damaging the organic EL element having the top emission structure. Therefore, a highly efficient and long-life element that is practically useful is manufactured. Is a difficult situation.
As another solution, it is disclosed that TFTs are formed so as to overlap each other on an organic EL element having a bottom emission structure (see, for example, Patent Document 1). However, the TFT used was composed of an organic semiconductor. An organic TFT made of an organic semiconductor can be formed on an organic EL element without damaging the organic EL element because it can be formed at a low temperature. However, the organic TFT has a problem in driving stability. In addition, there is a problem in reliability, for example, it is necessary to strictly seal against the outside air and humidity in order to improve storage stability. In addition, since the organic TFT has a low carrier mobility, the size (channel width) of the TFT becomes extremely large in order to increase the drive current. Therefore, it has been difficult to produce a high-definition and high-brightness organic EL display device.

On the other hand, the manufacture of a transistor using a silicon thin film has good stability and operational reliability. However, the manufacture requires a relatively high temperature thermal process. There was a problem because the EL element was damaged.
In recent years, active development of TFTs using semiconductor thin films of amorphous oxides that can be formed at low temperatures, such as In—Ga—Zn—O-based amorphous oxides, has been actively carried out (for example, Patent Document 2, Non-Patent Document 2). Patent Document 1). A TFT using an amorphous oxide semiconductor can be formed at room temperature and can be formed on a film, and thus has recently attracted attention as a material for an active layer of a film (flexible) TFT. In particular, Tokyo Institute of Technology, Hosono et al. Reported that a TFT using a-IGZO has a field effect mobility of about 10 cm ² / Vs even on a PEN substrate, which is higher than that of an a-Si TFT on glass. In particular, it has attracted attention as a film TFT (see, for example, Non-Patent Document 2).

However, in the case of using a TFT using the a-IGZO as a drive circuit of a display device, for ^example, the mobility of 1cm ² / Vs~10cm 2 / Vs, properties are insufficient, and high OFF current, ON / There is a problem that the OFF ratio is low. In particular, for use in a display device using an organic EL element, further improvement in mobility and improvement in the ON / OFF ratio are required.
JP 2005-242028 A JP 2006-165529 A IDW / AD'05, pages 845-846 (6, December, 2005) NATURE, Vol. 437 (November 25, 2004), pages 488-492

  An object of the present invention is to provide an organic EL display device in which a TFT for driving the organic EL element is arranged on the organic EL element, and a manufacturing method thereof. In particular, it is an object of the present invention to provide an active organic EL display device having a high aperture ratio, high definition, high brightness, high stability, high reliability, and a long lifetime, and a method for manufacturing the same.

The above-described problems of the present invention have been solved by the following means.
<1> An organic EL display device having an organic EL device having at least a lower electrode, an organic layer including at least a light emitting layer, and an upper electrode in sequence on a substrate, wherein at least a gate electrode, a gate insulating film, An organic EL display device comprising an active layer, a source electrode, a drain electrode, and a TFT for driving the organic EL element, wherein the active layer contains an oxide semiconductor.
<2> A protective insulating film is provided between the upper electrode and the transistor, and the upper electrode and the source electrode or the drain electrode are electrically connected through a contact hole formed in the protective insulating film. The organic EL display device according to <1>, wherein
<3> The organic EL display device according to <1> or <2>, wherein the lower electrode is a light transmissive electrode.
<4> The organic EL display device according to <3>, wherein the upper electrode is a light reflective electrode.
<5> The organic EL display device according to any one of <1> to <4>, wherein the lower electrode is an anode and the upper electrode is a cathode.
<6> The organic EL display device according to <5>, wherein the TFT has an N-type polarity.
<7> The organic EL display device according to any one of <1> to <6>, wherein the oxide semiconductor of the active layer is an amorphous oxide semiconductor.
<8> The organic EL display device according to any one of <1> to <7>, further comprising a resistance layer between the active layer and at least one of the source electrode and the drain electrode.
<9> The organic EL display device according to <8>, wherein the active layer is in contact with the gate insulating film, and the resistance layer is in contact with at least one of the source electrode and the drain electrode.
<10> The organic EL display device according to <9>, wherein the resistance layer is thicker than the active layer.
<11> The organic EL display device according to <8> or <9>, wherein electrical conductivity between the resistance layer and the active layer continuously changes.
<12> The organic EL display device according to any one of <8> to <11>, wherein an oxygen concentration of the active layer is lower than an oxygen concentration of the resistance layer.
<13> The organic EL according to any one of <1> to <12>, wherein the oxide semiconductor includes at least one selected from the group consisting of In, Ga, and Zn, or a composite oxide thereof. Display device.
<14> The oxide semiconductor contains the In and Zn, and the composition ratio of Zn and In (represented by the ratio of Zn to In, Zn / In) of the resistance layer is larger than the composition ratio Zn / In of the active layer <10> The organic EL display device according to <13>.
<15> The organic EL display device according to any one of <8> to <14>, wherein the electric conductivity of the active layer is 10 ⁻⁴ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ .
<16> The organic EL display device according to <15>, wherein the electric conductivity of the active layer is 10 ⁻¹ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ .
<17> The ratio of the electrical conductivity of the active layer to the electrical conductivity of the resistive layer (the electrical conductivity of the active layer / the electrical conductivity of the resistive layer) is from 10 ^{1 to} 10 ^10. <8> to the organic EL display device according to any one of <16>.
<18> The ratio of the electrical conductivity of the active layer to the electrical conductivity of the resistive layer (the electrical conductivity of the active layer / the electrical conductivity of the resistive layer) is 10 ² or more and 10 ⁸ or less. The organic EL display device according to <17>.
<19> The organic EL display device according to any one of <1> to <18>, wherein the substrate is a flexible resin substrate.
<20> A method for producing an organic EL display device according to any one of <1> to <19>, wherein an organic EL element and a TFT for driving the organic EL element are sequentially formed on a substrate. A method for manufacturing an organic EL display device.

A TFT using an oxide semiconductor can be formed at room temperature and can be disposed over the organic EL element without damaging the organic EL element. TFTs using oxide semiconductors have higher mobility than organic TFTs and can increase the current that can be passed through the organic EL elements, and can provide a display device with higher brightness, as well as driving stability and sealing film than organic TFTs. It is characterized by excellent storage stability, such as not requiring. In particular, by using an In—Ga—Zn—O-based oxide for an active layer, a TFT having a field effect mobility of 10 cm ² / Vs and an ON / OFF ratio exceeding 10 ³ can be manufactured. Further, the oxide semiconductor layer includes at least an active layer and a resistance layer having a lower electrical conductivity than the active layer, the active layer is in contact with the gate insulating film, and the active layer, the source electrode, and the drain electrode By adopting a configuration in which the resistance layer is electrically connected to at least one, it is possible to form a TFT having both excellent OFF characteristics and high mobility. In particular, an effective configuration is that at least the resistance layer and the active layer are formed in layers, the active layer is in contact with the gate insulating film, and the resistance layer is in contact with at least one of the source electrode and the drain electrode. It was issued.

  According to the present invention, a TFT for driving the organic EL element is provided on the organic EL element, a high aperture ratio is obtained, and high definition, high brightness, high stability, high reliability, and long-life active are obtained. Type organic EL display device and its manufacturing method can be provided.

1. Organic EL Display Device The organic EL display device according to the present invention includes an organic EL element having at least a lower electrode, an organic layer including at least a light emitting layer, and an upper electrode in sequence on a substrate, and at least a gate electrode and gate insulation on the upper electrode. The TFT includes a film, an active layer containing an oxide semiconductor, a source electrode, and a drain electrode, and drives the organic EL element. Since TFT is arrange | positioned at the back surface of an organic EL element, the opening part which takes out light emission of an organic EL element can be taken large. Preferably, a protective insulating film is provided between the TFT and the organic EL element, and the upper electrode of the organic EL element and the source electrode or the drain electrode of the TFT are connected via a contact hole formed in the protective insulating film. Electrically connected. Preferably, the lower electrode is a light transmissive electrode, and the upper electrode is a light reflective electrode.

Hereinafter, the organic EL display device of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic sectional view showing a configuration of an example of an organic EL display device of the present invention.
On the substrate 100, the lower electrode 30, the organic layer 32 including at least the light emitting layer, and the organic EL element portion having the upper electrode 34, the protective insulating film 106, and at least the source electrode 105a, the drain electrode 105b, the active layer 104, A TFT portion having a gate insulating film 103 and a gate electrode 102 is provided. The entire device is covered with an insulating film 36. One of the source electrode 105a and the drain electrode 105b and the upper electrode 34 are electrically connected by a contact hole 108 provided in the protective insulating film. In this configuration, the substrate and the lower electrode are transparent, the upper electrode is light reflective, and light generated by light emission is extracted outside through the substrate.
FIG. 2 is a schematic cross-sectional view showing the configuration of an organic EL display device according to another embodiment of the present invention.
The structure of the TFT is different from that in FIG. 1, and a gate electrode 112, a gate insulating film 113, a source electrode 115 a, a drain electrode 115 b, and an active layer 114 are provided on the protective insulating film 116. One of the source electrode 115 a and the drain electrode 115 b and the upper electrode 44 are electrically connected by a contact hole 118 provided through the protective insulating film 116 and the gate insulating film 113.
FIG. 3 is a schematic cross-sectional view showing the configuration of an organic EL display device according to still another aspect of the present invention.
Similar to FIG. 2, the structure of the TFT is different from that of FIG. 1, and a gate electrode 122, a gate insulating film 123, an active layer 124, a source electrode 125a, and a drain electrode 125b are provided on the protective insulating film 126. One of the source electrode 125 a and the drain electrode 125 b and the upper electrode 54 are electrically connected by a contact hole 128 provided through the protective insulating film 126 and the gate insulating film 123.

In any structure, the TFT is provided on the back surface on the side opposite to the light extraction surface of the organic EL element. Since the TFT used in the present invention for the purpose described later is excellent in ON / OFF characteristics and can supply a high current, it is possible to reduce the size sufficiently to cope with a high-density arrangement of organic EL elements. It is possible to provide a wide opening.
Therefore, an organic EL display device with high reliability, high definition, high brightness, and long life is provided.

2. TFT
The TFT used in the present invention has at least a gate electrode, a gate insulating film, an active layer, a source electrode, and a drain electrode in order, applies a voltage to the gate electrode, and controls a current flowing through the active layer, And an active element having a function of switching a current between the drain electrode and the drain electrode. An oxide semiconductor is used for the active layer of the TFT used in the present invention. An oxide semiconductor can be formed at a low temperature and can be formed with little damage to an organic EL element. In addition, the organic semiconductor such as pentacene is excellent not only in mobility but also in driving stability and storage stability. In particular, an amorphous oxide semiconductor is more preferable for the active layer of the TFT from the viewpoint of uniformity of TFT characteristics and characteristic stability. As the TFT structure, either a staggered structure or an inverted staggered structure can be formed.

Preferably, the polarity of the TFT is N-type.
The organic EL element is usually configured as a transparent anode using ITO for the lower electrode and a light-reflective cathode using Al for the upper electrode. The source or drain electrode of the driving TFT is preferably connected to the upper electrode, that is, the cathode of the organic EL element in terms of process or structure. For example, when the pixel circuit has a simple 2-transistor-1 capacity (2Tr-1C) configuration, the drain electrode of the TFT is connected to the cathode of the organic EL element, the anode of the organic EL element is grounded, and an N-type TFT is used. Particularly excellent performance is obtained in terms of driving characteristics. This is because the gate voltage of the driving TFT is not affected by the driving voltage of the organic EL element, so that stable driving is possible. Therefore, conventionally, it is not necessary to provide a compensation circuit such as 4Tr for stabilization, downsizing of the TFT portion is possible, and design of an organic EL display device with higher definition, higher luminance, and longer life is facilitated. .

Preferably, the active layer in the present invention contains an oxide semiconductor and can be formed at a low temperature. The oxide semiconductor in the present invention is preferably an amorphous oxide semiconductor.
The TFT in the present invention preferably has at least an active layer and a resistance layer having a lower electrical conductivity than the active layer, the active layer is in contact with the gate insulating film, and the active layer, the source electrode, and the drain electrode The resistance layer is electrically connected to at least one of the two. The resistance layer in the present invention also preferably contains an oxide semiconductor. In the following description, the active layer and the resistance layer are sometimes referred to as a semiconductor layer.
More preferably, at least the resistance layer and the active layer are formed in layers, the active layer is in contact with the gate insulating film, and the resistance layer is in contact with at least one of the source electrode and the drain electrode.
From the viewpoint of operational stability, it is preferable that the thickness of the resistance layer is larger than the thickness of the active layer.

As another aspect, an aspect in which the electrical conductivity between the resistance layer and the active layer continuously changes is also preferable. In this configuration, there is no clear boundary between the resistance layer and the active layer. 10% of the total thickness of the semiconductor layer including the resistance layer and the active layer is close to the gate insulating film, and 10% of the thickness of the semiconductor layer is close to the source electrode and the drain electrode. % Region is defined as the resistance layer.
Preferably, the oxygen concentration of the active layer is lower than the oxygen concentration of the resistance layer.

  Preferably, the oxide semiconductor includes at least one selected from the group consisting of In, Ga, and Zn, or a composite oxide thereof. More preferably, the oxide semiconductor contains In and Zn, and the composition ratio of Zn and In (represented by the ratio of Zn to In, Zn / In) of the resistance layer is greater than the composition ratio Zn / In of the active layer. large. Preferably, the Zn / In ratio of the resistance layer is 3% or more larger than the Zn / In ratio of the active layer, and more preferably 10% or more.

Preferably, the electric conductivity of the active layer is 10 ⁻⁴ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ . More preferably, it is 10 ⁻¹ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ . The electric conductivity of the resistance layer is preferably 10 ⁻² Scm ⁻¹ or less, more preferably 10 ⁻⁹ Scm ⁻¹ or more and less than 10 ⁻³ Scm ^−1, which is smaller than the electric conductivity of the active layer.
When the electric conductivity of the active layer is less than 10 ⁻⁴ Scm ⁻¹ , high field effect mobility cannot be obtained, and when it is 10 ² Scm ⁻¹ or more, the OFF current increases and good ON / OFF is achieved. Since the ratio cannot be obtained, it is not preferable.

Preferably, (the electric conductivity of the active layer / electric conductivity of the resistance layer) the ratio of the electric conductivity of the active layer to the electric conductivity of the resistance layer is 10 ¹ to 10 ¹⁰ or less, more preferably 10 ² or more and 10 ⁸ or less.
Further, from the viewpoint of operation stability, it is preferable that the thickness of the resistance layer is larger than the thickness of the active layer.
More preferably, the ratio of the thickness of the resistance layer to the thickness of the active layer is more than 1 and 100 or less, more preferably more than 1 and 10 or less. Preferably, the substrate is a flexible resin substrate.

Next, a more preferable TFT structure in the present invention will be described in detail with reference to the drawings.
1) Structure FIG. 4 is a schematic diagram showing an example of an inverted staggered structure, which is a TFT of the present invention. In the case where the substrate 1 is a flexible substrate such as a plastic film, an insulating layer 6 is disposed on one surface of the substrate 1, and a gate electrode 2, a gate insulating film 3, an active layer 4-1, and a resistance layer 4- 2 and a source electrode 5-1 and a drain electrode 5-2 are provided on the surface thereof. The active layer 4-1 is in contact with the gate insulating film 3, and the resistance layer 4-2 is in contact with the source electrode 5-1 and the drain electrode 5-2. The composition of the active layer 4-1 and the resistive layer 4-2 is such that the electrical conductivity of the active layer 4-1 when no voltage is applied to the gate electrode is greater than the electrical conductivity of the resistive layer 4-2. Is determined. Here, an oxide semiconductor disclosed in JP 2006-165529 A, for example, an In—Ga—Zn—O-based oxide semiconductor is used for the active layer. These oxide semiconductors are known to have higher electron mobility as the electron carrier concentration is higher. That is, the higher the electric conductivity, the higher the electron mobility.
According to the structure of the present invention, when the TFT is in an ON state where a voltage is applied to the gate electrode, the active layer serving as a channel has a large electric conductivity, so that the field effect mobility of the transistor is high, High ON current can be obtained. Since the electric resistance of the resistance layer is small in the OFF state and the resistance of the resistance layer is high, the OFF current is kept low, so that the ON / OFF ratio characteristics are greatly improved.

  Although not shown in the figure, the gist of the present invention is that the semiconductor layer is provided so that the electrical conductivity of the semiconductor layer in the vicinity of the gate insulating film is larger than the electrical conductivity of the semiconductor layer in the vicinity of the source electrode and the drain electrode. In particular, as long as the state can be obtained, the means for achieving the state is not limited to providing a plurality of semiconductor layers as shown in FIG. The electrical conductivity may change continuously.

  FIG. 5 is a schematic diagram showing an example of a top gate structure, which is a TFT of the present invention. When the substrate 1 is a flexible substrate such as a plastic film, an insulating layer 16 is disposed on one surface of the substrate 11, a source electrode 5-11 and a drain electrode 5-12 are provided on the insulating layer, and the resistance layer 4 −12, after the active layer 4-11 is laminated, the gate insulating film 13 and the gate electrode 12 are disposed. As in the inverted staggered configuration, the active layer 4-11 (high electrical conductivity layer) is in contact with the gate insulating film 13, and the resistance layer 4-12 (low electrical conductivity layer) is the source electrode 5-11 and the drain electrode. Contact 5-12. The composition of the active layer 4-11 and the resistive layer 4-12 so that the electrical conductivity of the active layer 4-11 when no voltage is applied to the gate electrode is greater than the electrical conductivity of the resistive layer 4-12. Is determined.

2) Electric conductivity The electric conductivity of the active layer and the resistance layer in the present invention will be described.
The electrical conductivity is a physical property value indicating the ease of electrical conduction of a substance. When the carrier concentration n and carrier mobility μ and e of the substance are assumed to be elementary charge, the electrical conductivity σ of the substance is expressed by the following equation. expressed.
σ = neμ
When the active layer or the resistance layer is an n-type semiconductor, the carriers are electrons, the carrier concentration indicates the electron carrier concentration, and the carrier mobility indicates the electron mobility. Similarly, when the active layer or the resistance layer is a p-type semiconductor, the carriers are holes, the carrier concentration indicates the hole carrier concentration, and the carrier mobility indicates the hole mobility. The carrier concentration and carrier mobility of the substance can be obtained by Hall measurement.
<How to find electrical conductivity>
By measuring the sheet resistance of a film whose thickness is known, the electrical conductivity of the film can be determined. Although the electrical conductivity of a semiconductor varies with temperature, the electrical conductivity described in the text indicates the electrical conductivity at room temperature (20 ° C.).

3) The gate insulating film a gate insulating _{film, SiO 2, SiN x, SiON} , Al 2 O 3, Y s O 3, Ta 2 O 5, insulator such as HfO _2, or at least two or more such compounds A mixed crystal compound is used. A polymer insulator such as polyimide can also be used as the gate insulating film.

The thickness of the gate insulating film is preferably 10 nm to 10 μm. The gate insulating film needs to be thickened to some extent in order to reduce leakage current and increase voltage resistance. However, increasing the thickness of the gate insulating film results in an increase in the driving voltage of the TFT. Therefore, it is more preferable that the film thickness of the gate insulating film is 50 nm to 1000 nm for an inorganic insulator and 0.5 μm to 5 μm for a polymer insulator. In particular, it is particularly preferable to use a high dielectric constant insulator such as HfO ₂ for the gate insulating film because TFT driving at a low voltage is possible even if the film thickness is increased.

4) Active layer and resistance layer It is preferable to use an oxide semiconductor for the semiconductor layer constituting the active layer and the resistance layer used in the present invention. In particular, an amorphous oxide semiconductor is more preferable. An oxide semiconductor, particularly an amorphous oxide semiconductor, can be formed at a low temperature, and thus can be formed over a flexible resin substrate such as a plastic. Good amorphous oxide semiconductors that can be manufactured at low temperatures include oxides containing In, oxides containing In and Zn, In, Ga, and Zn as disclosed in JP-A-2006-165529. It is known that InGaO ₃ (ZnO) _m (m is a natural number of less than 6) is preferable as the composition structure. These are n-type semiconductors whose carriers are electrons. Of _{course, ZnO · Rh 2 O 3,} CuGaO 2, a p-type oxide semiconductor such as SrCu ₂ O ₂ may be used for the semiconductor layer.

Specifically, the amorphous oxide semiconductor according to the present invention includes In—Ga—Zn—O, and the composition in the crystalline state is represented by InGaO ₃ (ZnO) _m (m is a natural number of less than 6). A physical semiconductor is preferred. In particular, InGaZnO ₄ is more preferable. As an amorphous oxide semiconductor having this composition, the electron mobility tends to increase as the electrical conductivity increases. Japanese Patent Laid-Open No. 2006-165529 discloses that the electric conductivity can be controlled by the oxygen partial pressure during film formation.

<Electrical conductivity of active layer and resistance layer>
In the present invention, the active layer is close to the gate insulating film and has a higher electric conductivity than the resistance layer close to the source electrode and the drain electrode.
More preferably, the ratio of the electrical conductivity of the active layer to the electrical conductivity of the resistive layer (the electrical conductivity of the active layer / the electrical conductivity of the resistive layer) is preferably 10 ^{1 to} 10 ¹⁰ , More preferably, it is 10 ² or more and 10 ⁸ or less. Preferably, the electric conductivity of the active layer is 10 ⁻⁴ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ . More preferably, it is 10 ⁻¹ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ . The electric conductivity of the resistance layer is preferably 10 ⁻¹ Scm ⁻¹ or less, more preferably 10 ⁻⁹ Scm ⁻¹ or more and 10 ⁻⁴ Scm ⁻¹ or less.

<Thickness of active layer and resistance layer>
The resistance layer is preferably thicker than the active layer. More preferably, the ratio of the thickness of the resistance layer to the thickness of the active layer is more than 1 and 100 or less, more preferably more than 1 and 10 or less.
The thickness of the active layer is preferably 1 nm to 100 nm, more preferably 2.5 nm to 30 nm. The thickness of the resistance layer is preferably 5 nm or more and 500 nm or less, and more preferably 10 nm or more and 100 nm or less.

By using a semiconductor layer composed of an active layer and a resistance layer having the above structure, a TFT transistor having a high mobility of 10 cm ² / (V · sec) or more and an ON / OFF ratio of 10 ⁶ or more is obtained. Can be realized.

<Measuring means for electrical conductivity>
As described above, the electrical conductivity of the semiconductor layer in the present invention is adjusted to be larger in the vicinity of the gate insulating film (active layer) than in the vicinity of the source and drain electrodes (resistance layer) of the semiconductor layer.
As a means for adjusting the electrical conductivity, the following means can be exemplified when the semiconductor layer is an oxide semiconductor.
(1) Adjustment by oxygen defect It is known that when an oxygen defect is formed in an oxide semiconductor, carrier electrons are generated and electric conductivity is increased. Therefore, the electric conductivity of the oxide semiconductor can be controlled by adjusting the amount of oxygen defects. Specific methods for controlling the amount of oxygen defects include oxygen partial pressure during film formation, oxygen concentration and treatment time during post-treatment after film formation, and the like. Specific examples of post-treatment include heat treatment at 100 ° C. or higher, oxygen plasma, and UV ozone treatment. Among these methods, a method of controlling the oxygen partial pressure during film formation is preferable from the viewpoint of productivity. JP-A 2006-165529 discloses that the electric conductivity of an oxide semiconductor can be controlled by adjusting the oxygen partial pressure during film formation, and this technique can be used.
(2) Adjustment by composition ratio It is known that the electrical conductivity changes by changing the metal composition ratio of an oxide semiconductor. For example, Japanese Patent Laid-Open No. 2006-165529 discloses that in InGaZn _1-X Mg _X O ₄ , the electrical conductivity decreases as the Mg ratio increases. In addition, in the oxide system of (In ₂ O ₃ ) _1-X (ZnO) _X , it has been reported that when the Zn / In ratio is 10% or more, the electrical conductivity decreases as the Zn ratio increases. ("New development of transparent conductive film II", CMC Publishing, P.34-35). As specific methods for changing these composition ratios, for example, in a film formation method by sputtering, targets having different composition ratios are used.
Alternatively, it is possible to change the composition ratio of the film by co-sputtering with a multi-source target and individually adjusting the sputtering rate.
(3) Adjustment by impurities By adding an element such as Li, Na, Mn, Ni, Pd, Cu, Cd, C, N, or P to an oxide semiconductor as an impurity, the electron carrier concentration is reduced. It is disclosed in Japanese Patent Application Laid-Open No. 2006-165529 that electric conductivity can be reduced. As a method for adding an impurity, an oxide semiconductor and an impurity element are co-evaporated, an ion of the impurity element is added to the formed oxide semiconductor film by an ion doping method, or the like.
(4) Adjustment by oxide semiconductor material In the above (1) to (3), the method for adjusting the electric conductivity in the same oxide semiconductor system has been described. Of course, the electric conductivity can be changed by changing the oxide semiconductor material. You can change the degree. For example, it is generally known that a SnO ₂ oxide semiconductor has a lower electrical conductivity than an In ₂ O ₃ oxide semiconductor. By changing the oxide semiconductor material in this manner, the electric conductivity can be adjusted. In particular, as an oxide material having low electrical conductivity, oxide insulator materials such as Al ₂ O ₃ , Ga ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , MgO, or HfO ₃ are known. These can also be used.
As means for adjusting the electrical conductivity, the above methods (1) to (4) may be used alone or in combination.

<Method for forming active layer>
As a method for forming the active layer, a vapor phase film forming method is preferably used with a polycrystalline sintered body of an oxide semiconductor as a target. Among vapor deposition methods, sputtering and pulsed laser deposition (PLD) are suitable. Furthermore, the sputtering method is preferable from the viewpoint of mass productivity.

  For example, the film is formed by controlling the degree of vacuum and the oxygen flow rate by RF magnetron sputtering deposition. The greater the oxygen flow rate, the smaller the electrical conductivity.

The formed film can be confirmed to be an amorphous film by a known X-ray diffraction method.
The film thickness can be determined by stylus surface shape measurement. The composition ratio can be determined by an RBS (Rutherford backscattering) analysis method.

5) Gate electrode Examples of the gate electrode in the present invention include metals such as Al, Mo, Cr, Ta, Ti, Au, and Ag, alloys such as Al-Nd and APC, tin oxide, zinc oxide, indium oxide, and oxide. Preferable examples include metal oxide conductive films such as indium tin (ITO) and indium zinc oxide (IZO), organic conductive compounds such as polyaniline, polythiophene, and polypyrrole, or mixtures thereof.
The thickness of the gate electrode is preferably 10 nm or more and 1000 nm or less.

  The electrode film formation method is not particularly limited, and may be a printing method, a wet method such as a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, a CVD method, a plasma CVD method, or the like. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material from among chemical methods. For example, when ITO is selected, it can be performed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. When an organic conductive compound is selected as the material for the gate electrode, it can be performed according to a wet film forming method.

6) Source electrode and drain electrode Examples of the source electrode and drain electrode material in the present invention include metals such as Al, Mo, Cr, Ta, Ti, Au, and Ag, alloys such as Al-Nd and APC, tin oxide, and oxidation. Preferred examples include metal oxide conductive films such as zinc, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO), organic conductive compounds such as polyaniline, polythiophene, and polypyrrole, or mixtures thereof.
The thickness of the source electrode and the drain electrode is preferably 10 nm or more and 1000 nm or less.

  The electrode film formation method is not particularly limited, and may be a printing method, a wet method such as a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, a CVD method, a plasma CVD method, or the like. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material from among chemical methods. For example, when ITO is selected, it can be performed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. Further, when an organic conductive compound is selected as a material for the source electrode and the drain electrode, it can be performed according to a wet film forming method.

7) Insulating film If necessary, an insulating film may be provided on the TFT. The insulating film has a purpose of protecting the semiconductor layer (active layer and resistance layer) from deterioration due to the atmosphere and a purpose of insulating the electronic device manufactured on the TFT.

Specific examples of the insulating film material include metal oxides such as MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, Fe ₂ O ₃ , Y ₂ O ₃ , or TiO ₂ , SiN _x , Metal nitrides such as SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , or CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene , Polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a copolymer main chain. Fluorine-containing copolymer having a cyclic structure, water absorption of 1% or more Examples include water-absorbing substances, moisture-proof substances having a water absorption rate of 0.1% or less, and the like.

  The method for forming the insulating film is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the MBE (molecular beam epitaxy) method, the cluster ion beam method, the ion plating method, the plasma polymerization method (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, or transfer method can be applied.

8) Post-treatment If necessary, heat treatment may be performed as a post-treatment of the TFT. The heat treatment is performed at a temperature of 100 ° C. or higher in the air or in a nitrogen atmosphere. The heat treatment may be performed after the semiconductor layer is formed or at the end of the TFT manufacturing process. By performing the heat treatment, there are effects such as suppression of in-plane variation in TFT characteristics and improvement in driving stability.

3. Organic EL device

Hereinafter, the organic EL device of the present invention will be described in detail.
The light-emitting element of the present invention has a cathode and an anode on a substrate, and an organic compound layer including an organic light-emitting layer (hereinafter sometimes simply referred to as “light-emitting layer”) between both electrodes. In view of the properties of the light emitting element, at least one of the anode and the cathode is preferably transparent.

In the present invention, the organic compound layer is preferably laminated in the order of the hole transport layer, the light emitting layer, and the electron transport layer from the anode side. Further, a hole injection layer is provided between the hole transport layer and the anode, and / or an electron transporting intermediate layer is provided between the light emitting layer and the electron transport layer. Further, a hole transporting intermediate layer may be provided between the light emitting layer and the hole transport layer, and similarly, an electron injection layer may be provided between the cathode and the electron transport layer.
Each layer may be divided into a plurality of secondary layers.

  Each layer constituting the organic compound layer can be suitably formed by any of dry film forming methods such as vapor deposition and sputtering, transfer methods, printing methods, coating methods, ink jet methods, and spray methods.

  Next, elements constituting the light emitting device of the present invention will be described in detail.

(substrate)
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the organic compound layer. Specific examples thereof include zirconia stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Norbornene resins, and organic materials such as poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The substrate structure may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

(anode)
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. As described above, the anode is usually provided as a transparent anode.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  In the organic electroluminescent element of the present invention, the formation position of the anode is not particularly limited and can be appropriately selected according to the use and purpose of the light emitting element. Is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  Note that the transparent anode is described in detail in Yutaka Sawada's “New Development of Transparent Electrode Film” published by CMC (1999), and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

(cathode)
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, LI, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these public relations can also be applied in the present invention.

  There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

In the present invention, the cathode formation position is not particularly limited, and may be formed on the entire organic compound layer or a part thereof.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

(Organic compound layer)
The organic compound layer in the present invention will be described.
The organic EL device of the present invention has at least one organic compound layer including a light emitting layer. As described above, other organic compound layers other than the light emitting layer include a hole transport layer, an electron transport layer, a positive layer, Examples thereof include a hole blocking layer, an electron blocking layer, a hole injection layer, and an electron injection layer.

  In the organic EL device of the present invention, each layer constituting the organic compound layer is preferably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods. Can do.

(Light emitting layer)
The organic light emitting layer receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer having a function of providing a field to emit light.
The light emitting layer in the present invention may be composed only of a light emitting material, or may be a mixed layer of a host material and a light emitting dopant. The luminescent dopant may be a fluorescent material or a phosphorescent material, and may be two or more kinds. The host material is preferably a charge transport material. The host material may be one type or two or more types, and examples thereof include a configuration in which an electron transporting host material and a hole transporting host material are mixed. Further, the light emitting layer may include a material that does not have charge transporting properties and does not emit light.
Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

  As the luminescent dopant in the present invention, any of phosphorescent luminescent materials and fluorescent luminescent materials can be used as the dopant.

  The light emitting layer in the present invention can contain two or more kinds of light emitting dopants in order to improve color purity and to broaden the light emission wavelength region. The luminescent dopant in the present invention is a dopant that satisfies the relationship of 1.2 eV> ΔIp> 0.2 eV and / or 1.2 eV> ΔEa> 0.2 eV with the host compound. This is preferable from the viewpoint of driving durability.

《Phosphorescent dopant》
In general, examples of the phosphorescent light-emitting dopant include complexes containing a transition metal atom or a lanthanoid atom.
For example, the transition metal atom is not particularly limited, but preferably includes ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum, and more preferably rhenium, iridium. And platinum, more preferably iridium and platinum.
Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. By Yersin, “Photochemistry and
Photophysics of Coordination Compounds "
Examples include the ligands described in Springer-Verlag, Inc., published in 1987, Akio Yamamoto, “Organic Metal Chemistry: Fundamentals and Applications,” published in 1982, published by Soukabo, Inc.

  The specific ligand is preferably a halogen ligand (preferably a chlorine ligand) or an aromatic carbocyclic ligand (for example, preferably 5 to 30 carbon atoms, more preferably 6 to 6 carbon atoms). 30, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a cyclopentadienyl anion, a benzene anion, or a naphthyl anion), a nitrogen-containing heterocyclic ligand (for example, preferably Has 5 to 30 carbon atoms, more preferably 6 to 30 carbon atoms, still more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline. Etc.), diketone ligand (for example, acetylacetone, etc.), carboxylic acid ligand (for example, preferably 2-30 carbon atoms, and more) Preferably, it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, such as an acetic acid ligand), an alcoholate ligand (for example, preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms). More preferably, it has 6 to 20 carbon atoms, such as phenolate ligand), silyloxy ligand (for example, preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 3 carbon atoms). 20 such as trimethylsilyloxy ligand, dimethyl-tert-butylsilyloxy ligand, triphenylsilyloxy ligand), carbon monoxide ligand, isonitrile ligand, cyano ligand, Phosphorus ligand (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 20 carbon atoms, and particularly preferably 6 to 20 carbon atoms. A rephenylphosphine ligand), a thiolato ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, still more preferably 6 to 20 carbon atoms, such as a phenylthiolato ligand) ), A phosphine oxide ligand (preferably having 3 to 30 carbon atoms, more preferably 8 to 30 carbon atoms, still more preferably 18 to 30 carbon atoms, such as a triphenylphosphine oxide ligand). More preferably, it is a nitrogen-containing heterocyclic ligand.

  The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, specific examples of the luminescent dopant include, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1. , WO 05/19373 A2, JP 2001-247859, JP 2002-302671, JP 2002-117978, JP 2003-133074, JP 2002-235076, JP 2003-123982, JP 2002-170684, EP 12112257, Special JP 2002-226495, JP 2002-234894, JP 2001247478, JP 2001-298470, JP 2002 73674, JP 2002-203678, JP 2002-203679, JP 2004-357799, JP 2006-256999, JP 2007-19462, JP 2007-84635, JP 2007-96259, and the like. Phosphorescent compounds and the like are mentioned. Among them, more preferable luminescent dopants include Ir complex, Pt complex, Cu complex, Re complex, W complex, Rh complex, Ru complex, Pd complex, Os complex, Eu complex, Tb complex. , Gd complex, Dy complex, and Ce complex. Particularly preferred is an Ir complex, a Pt complex, or a Re complex, among which an Ir complex or a Pt complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond. Or a Re complex. Furthermore, from the viewpoints of luminous efficiency, driving durability, chromaticity, etc., an Ir complex, a Pt complex, or a Re complex containing a tridentate or higher polydentate ligand is particularly preferable.

《Fluorescent luminescent dopant》
As the fluorescent light-emitting dopant, generally, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, pyran, perinone, oxadiazole, aldazine, Pyraridin, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, condensed polycyclic aromatic compounds (anthracene, phenanthroline, pyrene, perylene, rubrene, pentacene, etc. ), 8-quinolinol metal complexes, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene, polyphenylene, polyphenylene Polymeric compounds such as vinylene, organic silane, and the like, and their derivatives.

  Among these, specific examples of the luminescent dopant include the following, but are not limited thereto.

  The light-emitting dopant in the light-emitting layer is contained in an amount of 0.1% by mass to 50% by mass with respect to the total compound mass generally forming the light-emitting layer in the light-emitting layer. To 1 mass% to 50 mass%, and more preferably 2 mass% to 40 mass%.

  Although the thickness of the light emitting layer is not particularly limited, it is usually preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm, and more preferably 5 nm to 100 nm from the viewpoint of external quantum efficiency. More preferably.

<Host material>
As the host material used in the present invention, a hole transporting host material excellent in hole transportability (sometimes referred to as a hole transportable host) and an electron transporting host compound excellent in electron transportability (electron transportability) May be described as a host).

《Hole-transporting host》
Specific examples of the hole-transporting host used in the present invention include the following materials.
Pyrrole, indole, carbazole, azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone , Stilbene, silazane, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole), aniline copolymer, thiophene oligomer, polythiophene, etc. Conductive polymer oligomers, organic silanes, carbon films, and derivatives thereof.
Preferred are indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives, and more preferred are those having a carbazole group in the molecule. In particular, a compound having a t-butyl substituted carbazole group is preferable.

《Electron transporting host》
The electron transporting host in the light emitting layer used in the present invention preferably has an electron affinity Ea of 2.5 eV or more and 3.5 eV or less from the viewpoint of improving durability and lowering driving voltage. More preferably, it is 0.4 eV or less, and further preferably 2.8 eV or more and 3.3 eV or less. Further, from the viewpoint of improving durability and reducing driving voltage, the ionization potential Ip is preferably 5.7 eV or more and 7.5 eV or less, more preferably 5.8 eV or more and 7.0 eV or less, and 5.9 eV or more. More preferably, it is 6.5 eV or less.

Specific examples of such an electron transporting host include the following materials.
Pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazol, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, Fluorine-substituted aromatic compounds, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanines, and derivatives thereof (may form condensed rings with other rings), metal complexes and metals of 8-quinolinol derivatives Examples thereof include various metal complexes represented by metal complexes having phthalocyanine, benzoxazole or benzothiazol as a ligand.

Preferred examples of the electron transporting host include metal complexes, azole derivatives (benzimidazole derivatives, imidazopyridine derivatives, etc.), and azine derivatives (pyridine derivatives, pyrimidine derivatives, triazine derivatives, etc.). To metal complex compounds are preferred. The metal complex compound (A) is more preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal.
The metal ion in the metal complex is not particularly limited, but is preferably beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion, or palladium ion, more preferably beryllium ion, Aluminum ion, gallium ion, zinc ion, platinum ion, or palladium ion, and more preferably aluminum ion, zinc ion, or palladium ion.

  There are various known ligands contained in the metal complex. For example, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, H.C. Examples include the ligands described in Yersin, published in 1987, “Organometallic Chemistry: Fundamentals and Applications”, Sakai Hanafusa, Yamamoto Akio, published in 1982, and the like.

The ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Alternatively, it may be a bidentate or higher ligand, preferably a bidentate or higher and a hexadentate or lower ligand, or a bidentate or higher and lower 6 or lower ligand and a monodentate mixed ligand. preferable.
Examples of the ligand include an azine ligand (for example, pyridine ligand, bipyridyl ligand, terpyridine ligand, etc.), a hydroxyphenylazole ligand (for example, hydroxyphenylbenzimidazole coordination). And a hydroxyphenyl benzoxazole ligand, a hydroxyphenyl imidazole ligand, a hydroxyphenylimidazopyridine ligand, etc.), an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 carbon atom). To 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-12 carbon atoms, for example phenyl Carboxymethyl, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl oxy, and 4-biphenyloxy and the like.),

Heteroaryloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, and quinolyloxy. ), An alkylthio ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), arylthio ligands (Preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio), heteroarylthio ligand (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio , 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio, etc.), a siloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms). Particularly preferably, it has 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group.), An aromatic hydrocarbon anion ligand (preferably having 6 carbon atoms) To 30, more preferably 6 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, such as a phenyl anion, a naphthyl anion, an anthranyl anion, etc.), an aromatic heterocyclic anion ligand (preferably Has 1 to 30 carbon atoms, more preferably 2 to 25 carbon atoms, and particularly preferably 2 to 20 carbon atoms. Pyrrole anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzothiophene anion, etc.), indolenine anion ligand, etc. , Preferably a nitrogen-containing heterocyclic ligand, aryloxy ligand, heteroaryloxy group, or siloxy ligand, more preferably a nitrogen-containing heterocyclic ligand, aryloxy ligand, siloxy coordination Or an aromatic hydrocarbon anion ligand or an aromatic heterocyclic anion ligand.

  Examples of the metal complex electron transporting host include, for example, JP-A No. 2002-235076, JP-A No. 2004-214179, JP-A No. 2004-221106, JP-A No. 2004-221665, JP-A No. 2004-221068. And compounds described in JP-A-2004-327313.

  In the light emitting layer of the present invention, it is preferable in terms of color purity, light emission efficiency, and driving durability that the triplet lowest excitation level (T1) of the host material is higher than T1 of the phosphorescent light emitting material.

  Further, the content of the host compound in the present invention is not particularly limited, but from the viewpoint of light emission efficiency and driving voltage, it is 15% by mass to 95% by mass with respect to the total compound mass forming the light emitting layer. Preferably there is.

(Hole injection layer, hole transport layer)
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. The hole injection material and the hole transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, And the like.

  An electron-accepting dopant can be contained in the hole injection layer or the hole transport layer of the organic EL device of the present invention. As the electron-accepting dopant introduced into the hole-injecting layer or the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.

  Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, metal oxides such as vanadium pentoxide, and molybdenum trioxide.

  In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used. In addition, JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580, JP-A-2001-102175, JP-A-2001-2001. -160493, JP2002-252085, JP2002-56985, JP2003-157981, JP2003-217862, JP2003-229278, JP2004-342614, JP2005-72012, JP20051666667 The compounds described in JP-A-2005-209643 and the like can be suitably used.

  Among these, hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p-chloranil, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2 , 5-dichlorobenzoquinone, 1,2,4,5-tetracyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9- Luenone, 2,3,5,6-tetracyanopyridine or fullerene C60 is preferred, and hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p- Chloranil, p-bromanyl, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, 2,3-dichloronaphthoquinone, 1,2,4,5-tetracyanobenzene, 2,3-dichloro-5,6-dicyano Benzoquinone or 2,3,5,6-tetracyanopyridine is more preferred, and tetrafluorotetracyanoquinodimethane is particularly preferred.

  These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. It is further more preferable and it is especially preferable that it is 0.1 mass%-10 mass%.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and still more preferably 1 nm to 100 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

(Electron injection layer, electron transport layer)
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. The electron injection material and the electron transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

The electron injection layer or the electron transport layer of the organic EL device of the present invention can contain an electron donating dopant. The electron donating dopant introduced into the electron injecting layer or the electron transporting layer only needs to have an electron donating property and a property of reducing an organic compound, such as an alkali metal such as Li or an alkaline earth metal such as Mg. Transition metals including rare earth metals and reducing organic compounds are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds.
In addition, materials described in JP-A-6-212153, JP-A-2000-196140, JP-A-2003-68468, JP-A-2003-229278, JP-A-2004-342614, and the like can be used.

  These electron donating dopants may be used alone or in combination of two or more. The amount of the electron donating dopant varies depending on the type of material, but is preferably 0.1% by mass to 99% by mass, and 1.0% by mass to 80% by mass with respect to the electron transport layer material. Is more preferable, and 2.0 mass% to 70 mass% is particularly preferable.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Hole blocking layer)
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Electronic block layer)
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side. In the present invention, an electron blocking layer can be provided as the organic compound layer adjacent to the light emitting layer on the anode side. As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be applied.
The thickness of the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Drive)
The organic electroluminescence device of the present invention emits light by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Obtainable.
The driving method of the organic electroluminescence device of the present invention is described in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234658, and JP-A-8-2441047. The driving methods described in each publication, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429 and 6,023,308 can be applied.

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The light-emitting element of the present invention may be a so-called top emission type in which light emission is extracted from the anode side.

The organic EL device of the present invention can have a structure in which a charge generation layer is provided between a plurality of light emitting layers in order to improve luminous efficiency.
The charge generation layer is a layer having a function of generating charges (holes and electrons) when an electric field is applied and a function of injecting the generated charges into a layer adjacent to the charge generation layer.

The material for forming the charge generation layer may be any material having the above functions, and may be formed of a single compound or a plurality of compounds.
Specifically, it may be a conductive material, a semiconductive material such as a doped organic layer, or an electrically insulating material. Examples thereof include materials described in Japanese Patent Application Publication Nos. 11-329748, 2003-272860, and 2004-39617.
More specifically, transparent conductive materials such as ITO and IZO (indium zinc oxide), fullerenes such as C60, conductive organic materials such as oligothiophene, metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free Conductive organic materials such as porphyrins, metal materials such as Ca, Ag, Al, Mg: Ag alloy, Al: Li alloy, Mg: Li alloy, hole conductive material, electron conductive material, and a mixture thereof May be used.
The hole conductive material is, for example, a material in which a hole transporting organic material such as 2-TNATA or NPD is doped with an oxidant having an electron withdrawing property such as F4-TCNQ, TCNQ, or FeCl ₃ , or a P-type conductive material. The electron conductive material includes an electron transporting organic material doped with a metal or a metal compound having a work function of less than 4.0 eV, an N type conductive polymer, N type Type semiconductors. Examples of the N-type semiconductor include N-type Si, N-type CdS, and N-type ZnS. Examples of the P-type semiconductor include P-type Si, P-type CdTe, and P-type CuO.
Further, an electrically insulating material such as V ₂ O ₅ can be used for the charge generation layer.

  The charge generation layer may be a single layer or a stack of a plurality of layers. A structure in which a plurality of layers are stacked includes a conductive material such as a transparent conductive material and a metal material and a hole conductive material, or a structure in which an electron conductive material is stacked, and the above hole conductive material and electron conductive And a layer having a structure in which a functional material is laminated.

In general, it is preferable to select a film thickness and a material for the charge generation layer so that the visible light transmittance is 50% or more. The film thickness is not particularly limited, but is preferably 0.5 nm to 200 nm, more preferably 1 nm to 100 nm, still more preferably 3 nm to 50 nm, and particularly preferably 5 nm to 30 nm.
The method for forming the charge generation layer is not particularly limited, and the above-described method for forming the organic compound layer can be used.

The charge generation layer is formed between the two or more light emitting layers. The charge generation layer may include a material having a function of injecting charges into adjacent layers on the anode side and the cathode side. In order to improve the electron injection property to the layer adjacent to the anode side, for example, an electron injection compound such as BaO, SrO, Li ₂ O, LiCl, LiF, MgF ₂ , MgO, or CaF _{2 is used} as the anode of the charge generation layer. It may be laminated on the side.
In addition to the contents listed above, the charge generation layer material can be changed based on the descriptions in JP-A No. 2003-45676, U.S. Pat. Nos. 6,337,492, 6,107,734, and 6,872,472. You can choose.

The organic EL element in the present invention may have a resonator structure. For example, a multilayer mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflector on a transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them.
In order to form a resonant structure, the optical path length determined from the effective refractive index of the two reflectors and the refractive index and thickness of each layer between the reflectors is adjusted to the optimum value to obtain the desired resonant wavelength. Is done.
The calculation formula in the case of the first embodiment is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

For example, as described in “Monthly Display”, September 2000 issue, pages 33 to 37, the organic EL display can be a full color type, as described in the three primary colors (blue (B), green ( G), a three-color light emission method in which organic EL elements that emit light corresponding to red (R)) are arranged on a substrate, and a white method in which white light emission by an organic EL element for white light emission is divided into three primary colors through a color filter In addition, a color conversion method that converts blue light emission by an organic EL element for blue light emission into red (R) and green (G) through a fluorescent dye layer is known.
Moreover, the planar light source of a desired luminescent color can be obtained by using combining the organic EL element of the different luminescent color obtained by the said method. For example, a white light-emitting light source that combines blue and yellow light-emitting elements, a white light-emitting light source that combines blue, green, and red light-emitting elements.

4). Protective insulating film In the organic EL display device of the present invention, the entire organic EL element is protected by a protective insulating film. The protective insulating film has a function of reducing damage to the organic EL element when a TFT is formed on the organic EL element, and a function of electrically insulating the organic EL element and the TFT. Further, it is more preferable that the protective insulating film has a function of preventing a substance that promotes element deterioration such as moisture and oxygen from entering the element.

Specific _{examples, MgO, SiO, SiO 2,} Al 2 O 3, GeO, NiO, CaO, BaO, Fe 2 O 3, Y 2 O 3, TiO metal oxides such as _{2, SiN x,} SiN x O metal nitrides such as _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , and CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene , A copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a copolymer main chain containing a cyclic structure. Fluorine copolymer, water-absorbing substance with water absorption of 1% or more, water absorption Examples include moisture-proof substances having a rate of 0.1% or less.

  The method for forming the protective insulating film is not particularly limited. For example, a vacuum deposition method, a sputtering method, a reactive sputtering method, an MBE (molecular beam epitaxy) method, a cluster ion beam method, an ion plating method, a plasma polymerization method ( High frequency excitation ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

  Since the upper electrode of the organic EL element and the source or drain electrode of the driving TFT need to be electrically connected, it is necessary to make a contact hole in the protective insulating film. As a method for forming the contact hole, there are a wet etching method using an etchant, a dry etching method using plasma, an etching method using a laser, and the like.

5). Pixel Circuit Configuration of Organic EL Display Device FIG. 6 is a schematic diagram of a pixel circuit of an active matrix organic EL display device using TFT elements used in the present invention. The circuit of the display device in the present invention is not particularly limited to that shown in FIG. 6, and a conventionally known circuit can be applied as it is.

(application)
The organic EL display device of the present invention is applied in a wide range of fields including a mobile phone display, a personal digital assistant (PDA), a computer display, an automobile information display, a TV monitor, or general lighting.

  Hereinafter, the organic EL display device of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Example 1
1. 1. Production of organic EL display device 1-1. Production of Organic EL Display Device 1 An organic EL display device having the configuration shown in FIG. 1 was produced.
(Preparation of organic EL element part)
1) Formation of lower electrode Indium tin oxide (hereinafter abbreviated as ITO) was vapor-deposited on a glass substrate (Corning, product number: No. 1737) to a thickness of 150 nm to form an anode.

2) Formation of organic layer After washing, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer were sequentially provided.

The configuration of each layer is as follows. Each layer was provided by resistance heating vacuum deposition.
Hole injection layer: 4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine (abbreviated as 2-TNATA), thickness 140 nm.
Hole transport layer: N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviated as α-NPD), thickness 10 nm.
Light-emitting layer: a layer containing 5% by mass of CBP and Ir (ppy) ₃ with respect to CBP, thickness 20 nm.
Hole blocking layer: bis- (2-methyl-8-quinonylphenolate) aluminum (abbreviated as BAlq), thickness 10 nm.
Electron transport layer: Tris (8-hydroxyquinolinate) aluminum (abbreviated as Alq3), thickness 20 nm.
Electron injection layer: LiF, thickness 1 nm.

3) Upper electrode It patterned by the shadow mask so that element size might be set to 2 mm x 2 mm, and Al was vapor-deposited in thickness of 100 nm, and it was set as the cathode.

(Protective insulating film)
A 500 nm SiON film was formed on the upper electrode as a protective insulating film by an ion plating method. After film formation, contact holes were formed by laser.

(Production of driving TFT part)
1) Source electrode and drain electrode As a source electrode and a drain electrode, Mo was deposited to a thickness of 40 nm and ITO to a thickness of 40 nm by RF magnetron sputtering. The source electrode and the drain electrode were patterned by using a shadow mask at the time of sputtering. At this time, the gap between the source and drain electrodes was formed so that the channel length (L) = 200 μm and the channel width (W) = 1000 μm. The upper electrode (cathode) of the organic EL element and the drain electrode are electrically connected via a contact hole.

2) Active layer Using a polycrystalline sintered body having a composition of InGaZnO ₄ as a target, an IGZO deposited layer having a thickness of 50 nm was provided by RF magnetron sputtering vacuum deposition. The electric conductivity of the active layer was 5.7 × 10 ⁻³ Scm ⁻¹ . The active layer was patterned by using a shadow mask during sputtering.

3) Gate insulating film SiO ₂ was formed to 200 nm by RF magnetron sputtering vacuum deposition, and a gate insulating film was provided. Note that the gate insulating film was patterned by using a shadow mask during sputtering.

4) Gate electrode A deposited layer of Mo having a thickness of 100 nm was formed. The gate electrode was patterned by using a shadow mask during sputtering.

(Sealing)
The organic EL display device was sealed with a UV curable adhesive using a glass substrate (manufactured by Corning, product number NO.1737) as the sealing plate.

1-2. Production of Comparative Organic EL Display Device A In the organic EL display device 1, the active layer was deposited to a thickness of 50 nm using pentacene, which is an organic semiconductor. This was used as a comparative organic EL display device A.

1-3. Production of Organic EL Display Device 2 In the organic EL display device 1 of Example 1, the active layer was changed to the following two-layer configuration of an active layer and a resistance layer. A layer near the source electrode and the drain electrode was a resistance layer, and a layer near the gate insulating film was an active layer. Otherwise, the organic EL display device 2 of the present invention was produced in the same manner as the organic EL display device 1 of Example 1.

Resistance layer: IGZO was deposited to a thickness of 40 nm by RF magnetron sputtering vacuum deposition. The electric conductivity was 1.0 × 10 ⁻⁴ Scm ⁻¹ by adjusting the Ar flow rate and the O ₂ flow rate.
Active layer: IGZO was deposited to 10 nm. The electric conductivity was 2.6 × 10 ⁻¹ Scm ⁻¹ by adjusting the Ar flow rate and the O ₂ flow rate.

1-4. Production of Organic EL Display Device 3 In the organic EL display device 2, the glass substrate and the sealing plate are changed to a PEN substrate having a SiON thickness of 40 nm on both sides as a barrier layer, and the others are the same as in the organic EL display device 2 An organic EL display device 3 of the invention was produced.

2. Performance evaluation (evaluation items)
1) Electrical conductivity measurement method Physical property measurement sample in which these layers were directly provided in a thickness of 100 nm on the glass substrate (Corning, product number NO. 1737) under the same conditions as the production of the active layer in the organic EL display device. Was made. As a result of analyzing these physical property measurement samples by a well-known X-ray diffraction method, it was confirmed that all of these IGZO films were amorphous films.
The electrical conductivity of the sample for measuring physical properties was calculated from the measured sheet resistance and film thickness of the sample. Here, when the sheet resistance is ρ (Ω / □) and the film thickness is d (cm), the electrical conductivity σ (Scm ⁻¹ ) is calculated as σ = 1 / (ρ * d).
In this example, (manufactured by Mitsubishi Chemical Corporation) Loresta -GP in sheet resistance 10 ⁷ Ω / □ of less than area of the sample for measuring physical properties, high tester -UP (manufactured by Mitsubishi Chemical Corporation in sheet resistance 10 ⁷ Ω / □ or more regions ) In an environment of 20 ° C. A stylus type surface shape measuring device DekTak-6M (manufactured by ULVAC) was used for measuring the film thickness of the sample for measuring physical properties.
Moreover, as a result of performing the characteristics of the fabricated TFT using a semiconductor parameter analyzer 4156C (manufactured by Agilent Technologies), the TFT using the active layer of IGZO which is the configuration of the organic EL display device of the present invention has a positive gate voltage. It was confirmed that an N-type TFT in which the current between the source and the drain increases when applied to is shown.

2) Element performance (1) Luminance: Luminance was measured when 20 V was applied to the gate electrode of the driving TFT and 20 V was applied to the anode of the organic EL element.
(2) Driving durability: The gate voltage of the driving TFT and the voltage of the anode of the organic EL element were adjusted so that the initial luminance was 100 cd / m ^2, and the luminance after a 100-hour energization test was measured.

3. Performance Evaluation The results obtained are shown in Table 1.
From the results in Table 1, the organic EL display device 1 in which the oxide TFT is formed on the organic EL element has higher brightness and longer life than the organic EL display device A in which the organic TFT is formed on the conventional organic EL element. It turns out that. In addition, when the oxide semiconductor of the active layer is made into two layers (organic EL display device 3), higher brightness and longer life are obtained. It was also shown that the film substrate has higher luminance and longer life than the conventional organic EL display device A.

Example 2
2-1. Production of Organic EL Display Device 4 In the organic EL display device 1 of Example 1, the formation of the organic layer in the production of the organic EL element part was changed to the following method, and the organic EL display device 4 was produced.
<Formation of organic layer>
After washing, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer were sequentially provided.

The configuration of each layer is as follows. Each layer was provided by resistance heating vacuum deposition.
Hole injection layer: 4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine (abbreviated as 2-TNATA) and 2,3,5,6-tetrafluoro-7,7,8 , 8-tetracyanoquinodimethane (abbreviated as F4-TCNQ), containing 1% by mass with respect to 2-TNATA, thickness 160 nm.
Hole transport layer: N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviated as α-NPD), thickness 10 nm.
Light-emitting layer: a layer containing 13% by mass of 1,3-bis (carbazol-9-yl) benzone (abbreviated as mCP) and platinum complex Pt-1 with respect to mCP, thickness 60 nm.
Hole blocking layer: aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate (abbreviated as BAlq), thickness 40 nm.
Electron transport layer: Tris (8-hydroxyquinolinate) aluminum (abbreviated as Alq3), thickness 10 nm.
Electron injection layer: LiF, thickness 1 nm.

  The structures of the compounds used in the examples are shown below.

In the organic EL display device 4, the luminance was measured when 20V was applied to the gate electrode of the driving TFT and 20V was applied to the anode of the organic EL element. The organic EL display device 4 exhibited good blue light emission, and a luminance of 150 cd / m ² was obtained.

2-2. Production of Organic EL Display Device 5 In the organic EL display device 2 of Example 1, the formation of the organic layer in the production of the organic EL element part is changed to the formation of the organic layer in the organic EL display device 4, and the organic EL display device 5 is changed. Was made.
In the organic EL display device 5, the luminance was measured when 20V was applied to the gate electrode of the driving TFT and 20V was applied to the anode of the organic EL element. The organic EL display device 5 showed good blue light emission, and a luminance of 210 cd / m ² was obtained.

It is a schematic diagram which shows the structure of the organic electroluminescent display apparatus of this invention. It is a schematic diagram which shows the structure of another aspect of the organic electroluminescence display of this invention. It is a schematic diagram which shows the structure of another aspect of the organic electroluminescence display of this invention. It is a schematic diagram which shows the structure of TFT used for this invention. It is a schematic diagram which shows the structure of TFT of another aspect used for this invention. It is a schematic diagram of the pixel circuit of the organic EL display device of the present invention.

Explanation of symbols

1, 11, 100, 110, 120: Substrate 6, 16: Insulating layers 2, 12, 102, 112, 122: Gate electrodes 3, 13, 1032, 113, 123: Gate insulating films 4-2, 4-12: Resistance layers 4-1, 4-11: active layers 5-1, 5-11, 105a, 115a, 125a: source electrodes 5-2, 5-12, 105b, 115b, 125b: drain electrodes 30, 40, 50: Lower electrodes 32, 42, 52: organic layers 34, 44, 54: upper electrodes 106, 116, 126: protective insulating films 36, 46, 56: insulating films 108, 118, 128: contact holes

Claims (20)

  An organic EL display device having an organic EL element having at least a lower electrode, an organic layer including at least a light emitting layer, and an upper electrode in sequence on a substrate, wherein at least a gate electrode, a gate insulating film, an active layer, An organic EL display device comprising a thin film field effect transistor having a source electrode and a drain electrode for driving the organic EL element, wherein the active layer contains an oxide semiconductor.   A protective insulating film is provided between the upper electrode and the transistor, and the upper electrode and the source electrode or the drain electrode are electrically connected via a contact hole formed in the protective insulating film. The organic EL display device according to claim 1.   The organic EL display device according to claim 1, wherein the lower electrode is a light transmissive electrode.   The organic EL display device according to claim 3, wherein the upper electrode is a light reflective electrode.   The organic EL display device according to any one of claims 1 to 4, wherein the lower electrode is an anode and the upper electrode is a cathode.   6. The organic EL display device according to claim 5, wherein the thin film field effect transistor has an N-type polarity.   The organic EL display device according to claim 1, wherein the oxide semiconductor of the active layer is an amorphous oxide semiconductor.   The organic EL display device according to claim 1, further comprising a resistance layer between the active layer and at least one of the source electrode and the drain electrode.   9. The organic EL display device according to claim 8, wherein the active layer is in contact with the gate insulating film, and the resistance layer is in contact with at least one of the source electrode and the drain electrode.   The organic EL display device according to claim 9, wherein the thickness of the resistance layer is larger than the thickness of the active layer.   10. The organic EL display device according to claim 8, wherein electrical conductivity between the resistance layer and the active layer continuously changes.   The organic EL display device according to claim 8, wherein an oxygen concentration of the active layer is lower than an oxygen concentration of the resistance layer.   The organic EL display according to any one of claims 1 to 12, wherein the oxide semiconductor includes at least one selected from the group consisting of In, Ga, and Zn, or a composite oxide thereof. apparatus.   The oxide semiconductor contains the In and Zn, and the composition ratio of Zn and In (represented by the ratio of Zn to In, Zn / In) of the resistance layer is larger than the composition ratio Zn / In of the active layer The organic EL display device according to claim 13. The organic EL display device according to claim 8, wherein the active layer has an electric conductivity of 10 ⁻⁴ Scm ⁻¹ or more and less than 10 ² Scm ⁻¹ . The organic EL display device according to claim 15, wherein the electrical conductivity of the active layer is less than ¹⁰ -1 ^{Scm -1} or more ¹⁰ 2 ^{Scm -1.} The ratio of the electrical conductivity of the active layer to the electrical conductivity of the resistive layer (the electrical conductivity of the active layer / the electrical conductivity of the resistive layer) is 10 ¹ or more and 10 ¹⁰ or less. Item 17. The organic EL display device according to any one of Items 8 to 16. The ratio of the electrical conductivity of the active layer to the electrical conductivity of the resistive layer (the electrical conductivity of the active layer / the electrical conductivity of the resistive layer) is 10 ² or more and 10 ⁸ or less. Item 18. An organic EL display device according to Item 17.   The organic EL display device according to claim 1, wherein the substrate is a flexible resin substrate.   20. The method for manufacturing an organic EL display device according to claim 1, wherein an organic EL element and a thin film field effect transistor for driving the organic EL element are sequentially formed on a substrate. A method for producing an organic EL display device characterized by the above.