JPH11339964A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element having both merits of an organic material and an inorganic material and a long life and requiring a low operating voltage by laminating an inorganic material layer containing a chalcopyrite compound and a luminescent layer containing an organic compound participating in luminescent function on a substrate. SOLUTION: An inorganic material layer containing at least a chalcopyrite compound or a deformed chalcopyrite compound and a luminescent layer containing at least an organic compound participating in a luminescent function are laminated on a substrate to form an organic EL element. The chalcopyrite compound has a crystal structure similar to zincblende. A compound such as I-III-VI2 represented by CuAlS2 , II-IV-V2 represented by ZnSnAS2 , or II-III2 -VI4 represented by Al2 Se4 and a mixed crystal compound with multiple components are preferably used as the chalcopyrite compound. The inorganic material layer desirably has the band gap of 2.5 eV or above, preferably 2.7 eV or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL (electroluminescence) device, and more particularly, to an inorganic / organic junction structure used in a device that emits light by applying an electric field to a thin film of an organic compound.

[0002]

2. Description of the Related Art Recent developments in blue light-emitting devices have been remarkable. In particular, the following two R & D activities have been activated.
First, the present invention relates to an LED (light emitting diode) and an LD (laser diode) based on the basic principle of injection and recombination emission of electrons and holes by a semiconductor pn junction. Secondly, the present invention relates to an organic EL device which is formed by laminating an organic thin film serving as a light emitting layer together with an electron transporting and hole transporting organic substance, and injects and recombines electrons and holes similar to a semiconductor pn junction. is there.

The above-mentioned LEDs and LDs have been studied for a long time, but in recent years, GaN-based and ZnSe-based studies have been advanced, and for example, Nikkei Electronics No.674, p.
As shown in 79 (1996), an LED that includes a stacked structure of these nitride semiconductor layers and emits light of a short wavelength such as blue or green has already been developed. At present, there is a report on LD as a trial. The reason why it took a long time in the development of LED and LD was that Ga
This is because, with a wide gap semiconductor material such as N or ZnSe, an n-type semiconductor can be obtained, but a p-type semiconductor cannot be obtained. Recently, p-type has been reported due to the progress of the crystal growth technology, and LED has been made possible, and furthermore, rapid progress has been made with LD.

[0004] However, in mass production of blue devices, cost is a big problem compared to crystal growth conditions and equipment, and red LEDs such as a single crystal substrate to be used. At present, it is said that if the cost of a blue device is reduced by half, the market will be increased fivefold, and it is urgently necessary to reduce the price and improve the yield compared to the conventional technology.

On the other hand, organic EL devices are being researched and developed for display applications, since devices can be formed on glass over a large area. In general, an organic EL element is formed by forming a transparent electrode such as ITO on a glass substrate, and forming an organic amine-based hole transport layer thereon, and an organic light emitting layer made of, for example, an Alq ³ material which shows electron conductivity and emits strong light. The electrodes are stacked, and an electrode having a small work function such as MgAg is formed to form a basic element.

The element structure reported so far has a structure in which one or more organic compound layers are interposed between a hole injection electrode and an electron injection electrode. There is a two-layer structure or a three-layer structure.

Examples of the two-layer structure include a structure in which a hole transport layer and a light emitting layer are formed between a hole injection electrode and an electron injection electrode, or a light emitting layer and an electron transport layer between a hole injection electrode and an electron injection electrode. Is formed. As an example of the three-layer structure, there is a structure in which a hole transport layer, a light emitting layer, and an electron transport layer are formed between a hole injection electrode and an electron injection electrode. Also, a single-layer structure in which a single layer has all the functions has been reported for polymers and mixed systems.

FIGS. 3 and 4 show a typical structure of an organic EL device.

In FIG. 3, between a hole injection electrode 12 and an electron injection electrode 13 provided on a substrate 11, a hole transport layer 14, which is an organic compound, and a light emitting layer 15 are formed. In this case, the light emitting layer 15 also functions as an electron transport layer.

In FIG. 4, a hole transporting layer 14, which is an organic compound, a light emitting layer 15, and an electron transporting layer 16 are formed between a hole injection electrode 12 and an electron injection electrode 13 provided on a substrate 11.

In these organic EL devices, reliability is a common problem. That is, the organic EL element has a hole injection electrode and an electron injection electrode in principle, and requires an organic layer for injecting and transporting holes and electrons efficiently between these electrodes. However, these materials are susceptible to damage at the time of manufacturing, and have a problem in affinity with electrodes. In addition, degradation of the organic thin film LED,
There is a problem that it is significantly larger than LD.

In order to solve such a problem, there has been proposed a method utilizing the respective merits of an organic material and an inorganic semiconductor material. That is, an organic / inorganic semiconductor junction in which the organic hole transport layer is replaced with an inorganic p-type semiconductor. Such a study has been discussed in Japanese Patent No. 2636341, Japanese Patent Application Laid-Open No. 2-139983, Japanese Patent Application Laid-Open No. 2-207488, and Japanese Patent Application Laid-Open No. 6-119773. Element conventional organic EL
It was not possible to obtain characteristics exceeding 100.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic EL device which has the advantages of an organic material and an inorganic material, has a long life, has improved efficiency, and has a low operating voltage.

Another object of the present invention is to provide an organic EL device having a high practical value particularly for a high-performance flat type color display.

[0015]

This and other objects are achieved by any one of the following constitutions (1) to (3). (1) An organic EL element having a structure in which at least an inorganic layer containing a chalcopyrite compound or a modified chalcopyrite compound and a light-emitting layer containing at least an organic compound involved in a light-emitting function are stacked on a substrate. (2) The organic EL device according to (1), wherein the inorganic layer has a band gap of 2.5 eV or more. (3) The organic EL device according to (1) or (2), wherein the inorganic layer is a p-type semiconductor.

[0016]

According to the present invention, a layer formed of a chalcopyrite compound or a modified chalcopyrite compound, which is a p-type semiconductor made of an inorganic material, and a light emitting layer formed of an organic compound are laminated, and a hole transport layer of an organic electroluminescent device is provided. Is replaced by an organic compound to make a chemically stable inorganic material.

The role of hole injection into the light emitting layer, which is fulfilled by the hole transport layer of the organic electroluminescence device, is as follows.
An inorganic material capable of hole injection, that is, a p-type chalcopyrite compound or a modified chalcopyrite compound semiconductor functions.

An organic / inorganic junction which has been studied conventionally, that is, Japanese Patent No. 2636341, Japanese Patent Application Laid-Open No. Hei 2-13989.
No. 3, JP-A-2-207488, JP-A-6-207488
In Japanese Patent No. 1199973, as a p-type inorganic semiconductor material,
Si _1-x C _x (0 ≦ x1), CuI, CuS, GaAs
s, ZnTe, amorphous Si, and oxide semiconductor materials have been used.

We also conducted experiments to produce these junctions, ie, these inorganic p-type semiconductor / organic light emitting layers.
Alq ³ was used for the organic light emitting layer. However, when conducting a luminescence experiment, a large current flows and no luminescence is observed.
Or light emission was observed, but it was destroyed immediately due to the large current.

Therefore, in order to improve the organic / inorganic junction, the physical properties of the used organic and inorganic materials and the temperature characteristics of the conductivity of the junction were evaluated, and the improvement of the properties was examined.

The role of the hole transport layer or the p-type semiconductor in the organic electroluminescence device is to block electrons coming from the electron transporting light emitting layer and to inject holes of the hole transport layer or the p-type semiconductor into the light emitting layer. Must be fulfilled. However, in a conventional junction using a p-type semiconductor material, when a bias is applied to the junction, a large current flows before light emission. That is, the electrons in the light emitting layer are lost before the injection of holes occurs due to insufficient electron blocking of the p-type semiconductor.
Therefore, it is considered that sufficient light emission characteristics could not be obtained.

When the band gaps of the used p-type semiconductor thin films were measured, they were all 2.0 eV or less. The band gap of the used organic light emitting layer Alq ³ film was 2.6 eV. Here, FIG. 3 shows a band diagram at the junction of a p-type semiconductor of 2.0 eV or less and Alq ³ of 2.6 eV.

Looking at this diagram (A), A
To block the electron e coming from lq ³ 31, p
The electron affinity of the type semiconductor 32 must be 3.0 eV or less. If the electron affinity of the p-type semiconductor 32 is 3.0 eV or less, the ionization energy is 5.0 eV or less because the band gap is 2.0 eV or less. Alq ³ 31
Is 5.6 eV, so that at least the ionization energy gap between the p-type semiconductor 32 and the Alq ³ 31 is 0.6 eV or more. In the gap of 0.6 eV or more, the injection of the hole h is unlikely to occur.
Further, assuming a system (B) where the gap is set to 0.5 eV or less and holes h are easily injected, the band gap of the p-type semiconductor thin film 32 is 2.0 eV or less. Has an electron affinity of 3.0 eV or more, so that the electron e from the Alq ³ 31 cannot be blocked at all.

As described above, in the p-type semiconductor thin film having a band gap of 2.0 eV or less, the electrons e coming from the electron-transporting light-emitting layer are blocked, and the hole transport layer or the hole h of the p-type semiconductor is used as the light-emitting layer. It became clear that the injection role could not be fulfilled at the same time.

Therefore, the present inventor focused on a layer made of a chalcopyrite compound or a modified chalcopyrite compound which is a p-type semiconductor having a large band gap, instead of the p-type semiconductor thin film conventionally used in the organic / inorganic junction. .

That is, the present invention is characterized in that an inorganic layer made of a chalcopyrite compound or a modified chalcopyrite compound which is a p-type semiconductor having a large band gap is used instead of the conventional inorganic p-type semiconductor.
As a result, it is possible to block electrons coming from the electron-transporting light-emitting layer and to inject holes of the hole-transport layer or the p-type semiconductor into the light-emitting layer, thereby obtaining an element having stable light-emitting characteristics. Was.

As for the chalcopyrite compound, for example, Applied Physics Vol. 62, No. 2 (1998) Toshishi Kobayashi "Applied to chalcopyrite type semiconductors and light emitting devices", Applied Physics Vol. 57, No. 6 (1988) Iida Otsuka: "Optical Properties of Group I-III-VI2 and II-IV-V2 Compound Semiconductors", Japanese Patent Application Laid-Open No. 5-198840 and the like.

However, the light emitting devices discussed in the above-mentioned documents relate to LEDs or LDs.
There has not been studied any application to an organic EL device which emits light by an organic layer using an organic substance.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION In the organic EL device of the present invention, at least an inorganic layer containing a chalcopyrite compound or a modified chalcopyrite compound and a light-emitting layer containing at least an organic compound involved in a light-emitting function are formed on a substrate. It has a stacked structure. Further, the band gap of the inorganic layer is preferably 2.5 eV or more, and more preferably the inorganic layer is a p-type semiconductor.

The chalcopyrite compound or the modified chalcopyrite type compound has a crystal structure similar to zincite (zincblende). For example, two zincites are stacked and divalent Zn alternates with monovalent Cu. And trivalent Fe. The chalcopyrite compound or the modified chalcopyrite compound may be an epitaxial film, but a thin film having p-type conductivity can be easily obtained even from an amorphous or polycrystalline thin film. Doping is also easy. In addition, there is little change in electrical characteristics due to energization or temperature, and there is no electrochemical reaction with the electrode material. Furthermore, it is excellent in translucency.

The chalcopyrite compound or the modified chalcopyrite compound used in the present invention is a chalcopyrite compound, which is exemplified by I-III-V represented by CuAlS _2.
II-IV-V ₂ represented by I ₂ or ZnSnAs _2,
II-III ₂ -VI ₄ typified by ZnAl ₂ Se ₄ (here, Cu, Ag, etc. as Group I elements, Al, Ga, In, Tl, etc. as Group III elements, S, V, etc. as Group VI elements)
Group II elements such as Se and Te include Zn and Cd.
Compounds such as Si, Ge, and Sn as Group IV elements, and compounds such as P, As, and Sb as Group V elements, and mixed crystal compounds of combinations of a plurality of components using these compounds are preferable.

Examples of the modified chalcopyrite compound include C
I-III-IV-VI ₄ represented by uAlGeS ₄ (I, I
II, IV, VI is I ₅ -III-VI ₄ typified defect chalcopyrite similar to the above), a Cu ₅ AlSe ₄
(I, III, and VI are the same as described above) and a mixed crystal compound of a combination of a plurality of components using these compounds are preferable.

The composition ratios of these compounds do not strictly take the above-mentioned values, but each compound has a certain solid solubility limit. Therefore, the composition ratio may be within the range.

Among the above compounds, CuAlS
₂ , CuAlSe ₂ , CuGaS ₂ , CuGaSe ₂ ,
AgAlS ₂ , AgAlSe ₂ , AgGaS ₂ , AgG
aSe ₂ and their mixed crystal compounds are particularly preferable because they can be easily controlled in composition and become a wide-gap semiconductor.

Further, the inorganic layer of the present invention has a band gap of 2.5 eV or more, more preferably 2.7 eV or more, furthermore 3.0 eV or more, particularly 3.2 e.
Preferably, it is eV. The upper limit is not particularly limited, but is usually about 4 eV. When the band gap is 2.5 eV or more, electrons coming from the light-emitting layer having an electron-transport property can be blocked and holes can be injected into the light-emitting layer, so that an element having stable light-emitting characteristics can be obtained. The material used for the inorganic layer having a band gap of 2.5 eV or more may be appropriately selected from the above-described chalcopyrite compounds or modified chalcopyrite compounds.

Further, the inorganic layer of the present invention is more preferably a p-type semiconductor. Holes in the p-type semiconductor can be more efficiently injected into the light emitting layer, and an element having stable light emitting characteristics at a low voltage can be obtained. The material used for the inorganic layer of the p-type semiconductor may be appropriately selected from the above-mentioned chalcopyrite compounds or modified chalcopyrite compounds. Some of these compounds have p
Some of them exhibit the properties of a type semiconductor, but a known doping substance or gas is added during the production of these compounds to obtain p-type semiconductors.
It is preferable to carry out molding. It is particularly preferable to perform p-type conversion by shifting the composition without doping. Whether a semiconductor is a p-type semiconductor can be determined by Hall measurement or the Seebeck effect.

As the form of the inorganic layer, an amorphous thin film, a microcrystalline thin film, a polycrystalline thin film, an epitaxial thin film, a single crystal thin film, a mixed thin film thereof, a laminated thin film thereof or an artificial lattice thin film are used. Can be In particular, when a display element is used on a glass substrate, a polycrystalline thin film is preferable. Since the polycrystalline thin film can be formed over a large area and is crystalline, the semiconductor characteristics of the inorganic layer can be effectively used.

When the organic EL element is simply used as a light source or a single display, it is preferable to use an epitaxial thin film or a single crystal thin film.

Although the thickness of the inorganic layer is not particularly limited, it is about 1 to 300 nm. Particularly, the inorganic layer having a high resistivity, which is not strong in p-type, is used for driving the light emitting element at a low voltage. Is preferably 1 to 10 nm. The p-type inorganic layer may be relatively thick, and preferably 50 nm to 100 nm in order to have a large area and no pinholes.

This inorganic layer usually functions as a hole injection layer or a hole injection transport layer.

As a method for producing the inorganic layer, various physical or chemical thin film forming methods such as a sputtering method, a vapor deposition method, an MBE method, and a CVD method are used.
Post-treatment may be used after thin film formation such as post-annealing, selenization, or sulfuration to improve the characteristics.

The electron injecting electrode material is preferably a material having a low work function, for example, K, Li, Na, Mg, La, C
e, Ca, Sr, Ba, Al, Ag, In, Sn, Z
It is preferable to use a single metal element such as n or Zr, or a two-component or three-component alloy system containing them for improving the stability. As an alloy system, for example, Ag · Mg (A
g: 0.1 to 50 at%), Al.Li (Li: 0.01)
１２12 at%), In · Mg (Mg: 50 to 80 at%),
Al.Ca (Ca: 0.01 to 20 at%) and the like. Also, low-resistance semiconductors such as ZnO, ITO, G
aN and the like are preferable. As the electron injection electrode layer, a thin film made of these materials, or a multilayer thin film of two or more of these materials is used. A low-resistance semiconductor electrode can function as a hole injection electrode at the same time as being used as an electron injection electrode, so that the basic element structure can be multilayered.

The thickness of the electron injecting electrode thin film may be a certain thickness or more for sufficiently injecting electrons.
The thickness is preferably 0.5 nm or more, particularly 1 nm or more.
The upper limit is not particularly limited.
It may be about 500 nm. On the electron injection electrode,
Further, an auxiliary electrode (protection electrode) may be provided.

The thickness of the auxiliary electrode may be a certain thickness or more, preferably 50 nm or more, more preferably 100 nm or more, in order to secure electron injection efficiency and to prevent entry of moisture, oxygen or an organic solvent. The range of 100 to 1000 nm is preferred. If the auxiliary electrode layer is too thin, the effect cannot be obtained, and the step coverage of the auxiliary electrode layer is reduced, and the connection with the terminal electrode is not sufficient. on the other hand,
If the auxiliary electrode layer is too thick, the stress of the auxiliary electrode layer increases, so that the dark spot growth rate increases.

As the auxiliary electrode, an optimum material may be selected and used depending on the material of the electron injection electrode to be combined. For example, if importance is placed on ensuring electron injection efficiency, a low-resistance metal such as Al may be used, and if importance is placed on sealing properties, a metal compound such as TiN may be used.

The total thickness of the electron injection electrode and the auxiliary electrode is not particularly limited, but is usually 100 to 100.
It may be about 0 nm.

The hole injection electrode material is generally made of IT
O is used, but a low-resistance semiconductor such as ZnO or GaN is also preferable. The electrode on the light extraction side is preferably a transparent or translucent electrode. ITO is usually In ₂ O
_{Although 3} and SnO are contained in a stoichiometric composition, the amount of O may slightly deviate from this. Sn for In ₂ O ₃
The mixing ratio of O ₂ is 1 to 20% by weight, further 5 to 12% by weight.
Is preferred. In addition, Zn for In ₂ O ₃ in IZO
The mixing ratio of O ₂ is usually about 12 to 32% by weight.

Further, as a hole injection electrode material other than these, a conductive oxide is preferable, and particularly, a material containing the following conductive oxide is preferable.

NaCl type oxide: TiO, VO, Nb
O, RO _1-x (where, R: one or more rare earth elements (Sc
And Y), 0 ≦ x <1), LiVO _{2 and the} like.

Spinel type oxide: LiTi ₂ O ₄ , Li
M _x Ti _2-x O ₄ (where M = Li, Al, Cr, 0 <
_{x <2), Li 1-} x M x Ti 2 O 4 ( where, M = Mg,
Mn, 0 <x <1), LiV ₂ O ₄ , Fe ₃ O _{4 and the} like.

Perovskite oxide: ReO ₃ , WO
₃ , MxReO ₃ (where M metal, 0 <x <0.
5), MxWO ₃ (where M = metal, 0 <x <0.
5), A ₂ P ₈ W ₃₂ O ₁₁₂ (where A = K, Rb, T
l), Na _x Ta _y W _{1 -y} O ₃ (where 0 ≦ x <1,0
<Y <1), RNbO ₃ (where R: one or more rare earth elements (including Sc and Y)), Na _1-x Sr _x NbO ₃
(Where 0 ≦ x ≦ 1), RTiO ₃ (where R: one or more rare earth elements (including Sc and Y)), Can _{+ 1
Ti n O 3n + 1-y} ( where, n = 2,3, ..., y >
0), CaVO ₃ , SrVO ₃ , R _1-x Sr _x VO ₃ (where R: one or more rare earth elements (including Sc and Y);
0 ≦ x ≦ 1), R _1−x Ba _x VO ₃ (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1),
_{Sr n + 1 V n O 3n} + 1-y ( where, n = 1, 2,
3. . . . _{, Y> 0), Ba n} + 1 V n O 3n + 1-y ( where, n = 1,2,3 ...., y> 0), R 4 BaCu 5
O _13-y (where, R: one or more rare earth elements (including Sc and Y), 0 ≦ y), R ₅ SrCu ₆ O ₁₅ (where,
R: one or more rare earths (including Sc and Y)), R
₂ SrCu ₂ O ₆ . ₂ (where R: one or more rare earth elements (including Sc and Y)), R _1-x Sr _x VO ₃ (where R: one or more rare earth elements (including Sc and Y)), CaCrO ₃ , SrCrO ₃ , RMnO ₃ (where R: one or more rare earths (including Sc and Y)), R _1-x Sr _x MnO ₃ (where R: one or more rare earths (Sc and Y) ), 0 ≦ x ≦ 1), R
_1-x Ba _x MnO ₃ (where, R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1), Ca _1-x R _x M
nO _3-y (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1, 0 ≦ y), CaFeO ₃ ,
SrFeO ₃ , BaFeO ₃ , SrCoO ₃ , BaCo
O ₃ , RCoO ₃ (where R: one or more rare earths (including Sc and Y)), R _1-x Sr _x CoO ₃ (where R: one or more rare earths (including Sc and Y) ),
0 ≦ x ≦ 1), R _{1 −x} Ba _x CoO ₃ (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦
1), RNiO ₃ (where R: one or more rare earth elements (including Sc and Y)), RCuO ₃ (where R:
One or more rare earths (including Sc and Y)), RNb
O ₃ (where R: one or more rare earth elements (Sc and Y
The _{containing)), Nb 12 O 29,} CaRuO 3, Ca 1-x R x R
_{u 1-y Mn y O 3} ( wherein, R: one or more rare earth (S
c and Y), 0 ≦ x ≦ 1, 0 ≦ y ≦ 1), Sr
RuO ₃ , Ca _1-x Mg _x RuO ₃ (where 0 ≦ x ≦
1), Ca _1-x Sr _x RuO ₃ (where 0 <x <1),
BaRuO ₃ , Ca _1-x Ba _x RuO ₃ (where 0 <x
<1), (Ba, Sr) RuO ₃ , Ba _1-x K _x RuO ₃
(Where 0 <x ≦ 1), (R, Na) RuO ₃ (where R: one or more rare earth elements (including Sc and Y)), (R, M) RhO ₃ (where R : One or more rare earth elements (including Sc and Y), M = Ca, Sr, B
a), SrIrO ₃ , BaPbO ₃ , (Ba, Sr) P
bO _3-y (where 0 ≦ y <1), BaPb _1-x Bi _x O
₃ (where 0 <x ≦ 1), Ba _1−x K _x BiO ₃ (where 0 <x ≦ 1), Sr (Pb, Sb) O _3-y (where 0 ≦ y <1 ), Sr (Pb, Bi) O _3-y (where 0 ≦ y <1), Ba (Pb, Sb) O _3-y (where 0 ≦ y <1), Ba (Pb, Bi) O _3-y (where 0 ≦ y <1), MMoO ₃ (where M = Ca, S
r, Ba), (Ba, Ca, Sr) TiO _3-x (where 0 ≦ x) and the like.

Layered perovskite oxide (K ₂ NiF ₄₎
Type): R _{n + 1} Ni _n O _{3n + 1} (where R: Ba,
Sr, rare earth (including Sc and Y) one or more of, n = 1 to 5 _{integer), R n + 1 Cu n} O 3n + 1 ( where, R: Ba, Sr, rare earth (Sc and Y ), At least one of n = 1 to 5), Sr ₂ RuO
₄ , Sr ₂ RhO ₄ , Ba ₂ RuO ₄ , Ba ₂ RhO ₄
etc.

Pyrochlore type oxide: R ₂ V ₂ O _7-y (where R is one or more rare earth elements (including Sc and Y), 0 ≦ y <1), Tl ₂ Mn ₂ O _7-y (Where 0 ≦
y <1), R ₂ Mo ₂ O _7-y (where R: one or more rare earth elements (including Sc and Y), 0 ≦ y <1), R ₂ R
u ₂ O _7-y (where, at least one of R: Tl, Pb, Bi, rare earth (including Sc and Y), 0 ≦ y <
1), Bi _2-x Pb _x Pt _2-x Ru _x O _7-y (where 0
≦ x ≦ 2, 0 ≦ y <1), Pb ₂ (Ru, Pb) O _7-y
(Where 0 ≦ y <1), R ₂ Rh ₂ O _7-y (where,
R: at least one of Tl, Pb, Bi, Cd, rare earth (including Sc and Y), 0 ≦ y <1), R ₂ Pd ₂ O _7−
y (where R: Tl, Pb, Bi, Cd, rare earth (S
c and Y), 0 ≦ y <1),
R ₂ Re ₂ O _7-y (where R: Tl, Pb, Bi, C
d, one or more of rare earths (including Sc and Y),
0 ≦ y <1), R ₂ Os ₂ O _{7 −y} (where R: Tl,
At least one of Pb, Bi, Cd, rare earths (including Sc and Y), 0 ≦ y <1), R ₂ Ir ₂ O _7-y (where R: Tl, Pb, Bi, Cd, rare earths) (Including Sc and Y), at least one of 0 ≦ y <1), R ₂ Pt ₂
O _7-y (where, at least one of R: Tl, Pb, Bi, Cd, rare earth (including Sc and Y), 0 ≦ y <
1) etc.

Other oxides: R ₄ Re ₆ O ₁₉ (where R: one or more rare earth elements (including Sc and Y)), R ₄ Ru ₆ O ₁₉ (where R: one or more kinds of rare earth elements) Rare earth (including Sc and Y)), Bi ₃ Ru ₃ O ₁₁ , V ₂
O ₃ , Ti ₂ O ₃ , Rh ₂ O ₃ , VO ₂ , CrO ₂ , Nb
O ₂ , MoO ₂ , WO ₂ , ReO ₂ , RuO ₂ , RhO
₂ , OsO ₂ , IrO ₂ , PtO ₂ , PdO ₂ , V ₃ O _{5
, V n O 2n-1 (} n = 4 to 9 integer), SnO _2-x
(Where 0 ≦ x <1), La ₂ Mo ₂ O ₇ , (M, M
o) O (wherein, M = Na, K, Rb , Tl), Mo n
O _3n-1 (n = 4, 8, 9, 10), Mo ₁₇ O ₄₇ , Pd
_1-x Li _x O (where x ≦ 0.1) and the like. An oxide containing In.

Of these, oxides containing In or oxides of conductive perovskite are particularly preferred, and In ₂
O ₃ , In ₂ O ₃ (Sn doped), RCoO ₃ , RMn
O ₃ , RNiO ₃ , R ₂ CuO ₄ , (R, Sr) CoO ₃
, (R, Sr, Ca) RuO ₃ , (R, Sr) RuO ₃
, SrRuO ₃ , (R, Sr) MnO ₃ (R is a rare earth containing Y and Sc), and their related compounds are preferred. In general, a conductive oxide has a large work function and is preferable as a hole injection electrode. As the hole injection electrode layer, a thin film made of these materials, or a multilayer thin film of two or more of them is used. Many of the perovskite oxides are opaque. In this case, a transparent electrode is used as an electron injection electrode, and emitted light is extracted from the electron injection electrode side.

The electrode on the side from which light is extracted has an emission wavelength band,
The light transmittance is usually 400 to 700 nm, particularly preferably 80% or more, particularly 90% or more for each emitted light.
When the transmittance is low, the light emission from the light emitting layer itself is attenuated, and it becomes difficult to obtain the luminance required for the light emitting element.

The thickness of the electrode is 50 to 500 nm, especially 50
The range of -300 nm is preferred. The upper limit is not particularly limited. However, if the thickness is too large, there is a fear that the transmittance is reduced or the layer is peeled off. If the thickness is too small, a sufficient effect cannot be obtained, and there is a problem in film strength at the time of production and the like.

As shown in FIG. 1, for example, the device of the present invention comprises a substrate 1, a hole injection electrode 2, an inorganic layer 4, and a light emitting layer 5.
/ Electron injection electrode 6 may be sequentially laminated. In addition, as shown in FIG.
The light emitting layer 5 / the inorganic material layer 4 / the hole injecting electrode 2 may be stacked in the reverse order. These are appropriately selected and used depending on, for example, a display manufacturing process.
In particular, when an opaque material is used for the hole injection electrode 2, the structure shown in FIG. 2 is preferable. 1 and 2, a drive power source E is connected between the hole injection electrode 2 and the electron injection electrode 6.

The device of the present invention may be stacked in multiple layers with electrode layers / inorganic layers and light emitting layers / electrode layers / inorganic layers and light emitting layers / electrode layers / inorganic layers and light emitting layers / electrode layers. . With such an element structure, it is possible to adjust the color tone of the emitted light and to increase the number of colors.

The light emitting layer is composed of a laminated film of one or two or more organic compound thin films involved in at least the light emitting function.

The organic compound has high emission quantum efficiency,
Those having a π-electron system which is easily subjected to external perturbation and which are easily excited are preferable.

The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. By using a relatively electronically neutral compound for the light emitting layer, electrons and holes can be easily injected and transported in a well-balanced manner.

The light emitting layer may have a hole transporting layer, an electron injection transporting layer, etc. in addition to the light emitting layer in a narrow sense, if necessary.

The hole transport layer provided as necessary has a function of facilitating the injection of holes from the inorganic layer, a function of stably transporting holes, and a function of hindering electrons. It has a function of facilitating the injection of electrons from the injection electrode, a function of stably transporting electrons, and a function of preventing holes. These layers increase and confine holes and electrons injected into the light emitting layer, optimize the recombination region, and improve luminous efficiency.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and vary depending on the forming method.
It is preferable that the thickness be in the range of 10 to 300 nm.

The thickness of the hole transport layer and the thickness of the electron injection / transport layer depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. When the electron injection layer and the transport layer are separated from each other, the thickness of the injection layer is preferably 1 nm or more, and the thickness of the transport layer is preferably 1 nm or more. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 500 nm for the injection layer and about 500 nm for the transport layer. Such a film thickness is the same when two injection / transport layers are provided.

The light emitting layer of the organic EL device contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include, for example, JP-A-63-26469.
No. 2 discloses at least one compound selected from compounds such as quinacridone, rubrene, and styryl dyes. Also, Tris (8
-Quinolinolato) quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand such as aluminum, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Further, phenylanthracene derivatives disclosed in Japanese Patent Application No. 6-110569, and Japanese Patent Application No. 6-11445.
No. 6 tetraarylethene derivative or the like can be used.

Further, it is preferable to use in combination with a host substance capable of emitting light by itself, and it is preferable to use it as a dopant. In such a case, the content of the compound in the light emitting layer is 0.01 to 10% by weight, and more preferably 0.1 to 10% by weight.
It is preferably 1 to 5% by weight. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

The host substance is preferably a quinolinolato complex, and more preferably an aluminum complex having 8-quinolinol or a derivative thereof as a ligand. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7073
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum Oxide, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
Quinolinolato) calcium, 5,7-dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-
8-hydroxyquinolinolato) aluminum and poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane].

In addition to 8-quinolinol or a derivative thereof, an aluminum complex having another ligand may be used, such as bis (2-methyl-
8-quinolinolato) (phenolato) aluminum (III)
, Bis (2-methyl-8-quinolinolato) (ortho-
Cresolato) aluminum (III), bis (2-methyl-
8-quinolinolato) (meth-cresolate) aluminum
(III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolate)
Aluminum (III), bis (2-methyl-8-quinolinolato) (meth-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2-
Methyl-8-quinolinolato) (2,3-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(3,4-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III) ), Bis (2-methyl-8)
-Quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(2,3,6-trimethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (2,
3,5,6-tetramethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2-methyl-8
-Quinolinolato) (2-naphthrat) aluminum (II
I), bis (2,4-dimethyl-8-quinolinolato)
(Ortho-phenylphenolato) aluminum (III),
Bis (2,4-dimethyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (meta-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2 4-dimethyl-8
-Quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl) -4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III),
Bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III);

In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-
Methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-
2-methyl-8-quinolinolato) aluminum (III)-
μ-oxo-bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4
-Methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolinolato)
Aluminum (III), bis (5-cyano-2-methyl-
8-quinolinolato) aluminum (III) -μ-oxo-
Bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ
-Oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like.

Other host materials include Japanese Patent Application No.
Also preferred are phenylanthracene derivatives described in -110569 and tetraarylethene derivatives described in Japanese Patent Application No. 6-114456.

The light emitting layer may also serve as an electron injection / transport layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. These fluorescent substances may be deposited.

The light emitting layer is preferably a mixed layer of at least one kind of hole injecting and transporting compound and at least one kind of electron injecting and transporting compound, if necessary.
Further, it is preferable that a dopant is contained in the mixed layer. The content of the compound in such a mixed layer is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight.

In the mixed layer, a carrier hopping conduction path is formed, so that each carrier moves in a polarly advantageous substance, and carrier injection of the opposite polarity is less likely to occur, so that the organic compound is less susceptible to damage. This has the advantage that the element life is extended. Further, by including the above-described dopant in such a mixed layer, the emission wavelength characteristics of the mixed layer itself can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity is increased, The stability of the device can be improved.

The hole injecting / transporting compound and the electron injecting / transporting compound used in the mixed layer may be selected from a compound for a hole transporting layer and a compound for an electron injecting / transporting layer, respectively, which will be described later. Among them, as the compound for the hole injecting and transporting layer, amine derivatives having strong fluorescence, for example, a triphenyldiamine derivative as a hole transporting material,
Further, it is preferable to use a styrylamine derivative or an amine derivative having an aromatic condensed ring.

As the compound capable of injecting and transporting electrons, it is preferable to use a quinoline derivative, furthermore a metal complex having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato) aluminum (Alq ³ ). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound for the hole transport layer, an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is the above-mentioned hole transport material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring is used. Is preferred.

The mixing ratio in this case depends on the respective carrier mobilities and carrier concentrations. In general, the weight ratio of the compound of the hole injecting / transporting compound / the compound having the electron injecting / transporting function is from 1/99 to less. 99/1, more preferably 10/90 to 90/10, particularly preferably 20/80
It is preferable to set it to about 80/20.

The thickness of the mixed layer is preferably not less than the thickness of one molecular layer and less than the thickness of the organic compound layer. Specifically, the thickness is preferably 1 to 85 nm, more preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method of forming the mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are approximately the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

In the hole transport layer, for example, JP-A-63-295695, JP-A-2-191694, JP-A-3-792, JP-A-5-23468
No. 1, JP-A-5-239455, JP-A-5-239455
299174, JP-A-7-126225,
JP-A-7-126226, JP-A-8-10017
Various organic compounds described in JP-A No. 2,650 / 955A1, etc. can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine, a hydrazone derivative, a carbazole derivative, a triazole derivative, an imidazole derivative, an oxadiazole derivative having an amino group, polythiophene, etc. . These compounds may be used alone or in combination of two or more. When two or more kinds are used in combination, they may be stacked as separate layers or mixed.

The electron injecting and transporting layer, which is provided as necessary, includes tris (8-quinolinolato) aluminum (Alq
³ ), quinoline derivatives such as organometallic complexes having 8-quinolinol or a derivative thereof as a ligand, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, etc. Can be used. The electron injection / transport layer may also serve as the light emitting layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. The electron injecting and transporting layer may be formed by vapor deposition or the like, similarly to the light emitting layer.

In the case where the electron injecting and transporting layer is divided into an electron injecting layer and an electron transporting layer, a preferable combination can be selected from the compounds for the electron injecting and transporting layer. At this time, it is preferable to stack the compounds in descending order of the electron affinity value from the electron injection electrode side. Such a stacking order is the same when two or more electron injection / transport layers are provided.

For forming the hole transport layer, the light emitting layer and the electron injection transport layer, it is preferable to use a vacuum evaporation method since a uniform thin film can be formed. When a vacuum deposition method is used, a homogeneous thin film having an amorphous state or a crystal grain size of 0.1 μm or less can be obtained. If the crystal grain size exceeds 0.1 μm, non-uniform light emission occurs, the driving voltage of the device must be increased, and the hole injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
The degree of vacuum is 0 ^-4 Pa or less, and the deposition rate is 0.01 to 1 nm /
It is preferable to set it to about sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the occurrence and growth of dark spots can be suppressed.

When a plurality of compounds are contained in one layer when a vacuum evaporation method is used for forming each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

Further, in order to prevent oxidation of the organic layers and electrodes of the element, it is preferable to seal the element with a sealing plate or the like. The sealing plate adheres and seals the sealing plate using an adhesive resin layer in order to prevent moisture from entering. The sealing gas is A
An inert gas such as r, He, and N ₂ is preferable. Further, the moisture content of the sealing gas is preferably 100 ppm or less, more preferably 10 ppm or less, and particularly preferably 1 ppm or less. Although there is no particular lower limit for the water content, it is usually about 0.1 ppm.

The material of the sealing plate is preferably a flat plate, and may be a transparent or translucent material such as glass, quartz, resin, etc., but glass is particularly preferred. As such a glass material, an alkali glass is preferable from the viewpoint of cost, and in addition, a glass composition such as soda lime glass, lead alkali glass, borosilicate glass, aluminosilicate glass, and silica glass is also preferable. In particular, soda glass, a glass material without surface treatment can be used at low cost,
preferable. As the sealing plate, other than a glass plate, a metal plate, a plastic plate, or the like can be used.

The height of the sealing plate may be adjusted by using a spacer to keep the sealing plate at a desired height. Examples of the material of the spacer include resin beads, silica beads, glass beads, and glass fibers, and glass beads are particularly preferable. The spacer is usually a granular material having a uniform particle size, but the shape is not particularly limited, and may be various shapes as long as it does not hinder the function as the spacer. As the size, the diameter in terms of a circle is 1 to 20 μm, more preferably 1 to 10 μm, and especially 2 to 20 μm.
8 μm is preferred. Those having such a diameter have a grain length of 10
It is preferably about 0 μm or less, and the lower limit is not particularly limited, but is usually about the same as or larger than the diameter.

When a recess is formed in the sealing plate,
Spacers may or may not be used. The preferred size when used is within the above range,
Particularly, the range of 2 to 8 μm is preferable.

The spacer may be mixed in the sealing adhesive in advance, or may be mixed at the time of bonding. The content of the spacer in the sealing adhesive is preferably 0.01
-30 wt%, more preferably 0.1-5 wt%.

The adhesive is not particularly limited as long as it can maintain stable adhesive strength and has good airtightness, but it is preferable to use a cationic curing type ultraviolet curing epoxy resin adhesive. .

In the present invention, the substrate on which the organic EL structure is formed is an amorphous substrate such as glass or quartz, or a crystalline substrate such as Si, GaAs, ZnSe, or Z.
Examples thereof include nS, GaP, and InP, and a substrate in which a crystalline, amorphous, or metal buffer layer is formed on these crystalline substrates can also be used. As the metal substrate, Mo, Al, Pt, Ir, Au, Pd, or the like can be used, and a glass substrate is preferably used. Since the substrate is usually on the light extraction side, it is preferable that the substrate has the same light transmittance as the above-mentioned electrodes.

Further, a large number of the elements of the present invention may be arranged on a plane. By changing the emission color of each element arranged on a plane, a color display can be obtained.

The luminescent color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate.

As the color filter film, a color filter used in a liquid crystal display or the like may be used.
The characteristics of the color filter may be adjusted in accordance with the light emitted from the organic EL element to optimize the extraction efficiency and the color purity.

If a color filter capable of cutting off short-wavelength external light that is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance of the element and the display contrast are improved.

Further, an optical thin film such as a dielectric multilayer film may be used instead of the color filter.

The fluorescence conversion filter film absorbs EL light and emits light from the phosphor in the fluorescence conversion film to convert the color of the emitted light. It is formed from a fluorescent material and a light absorbing material.

As the fluorescent material, basically, a material having a high fluorescence quantum yield may be used, and it is desirable that the fluorescent material has strong absorption in the EL emission wavelength region. In practice, laser dyes and the like are suitable, and rhodamine compounds, perylene compounds, cyanine compounds, phthalocyanine compounds (including subphthalocyanines, etc.) naphthalimide compounds, condensed ring hydrocarbon compounds, condensed heterocyclic compounds A styryl compound, a coumarin compound or the like may be used.

As the binder, a material that does not quench the fluorescence may be basically selected, and a binder that can be finely patterned by photolithography, printing, or the like is preferable. Further, when formed on the substrate in contact with the hole injection electrode, it is preferable to use a material which will not be damaged when forming ITO or IZO.

The light absorbing material is used when the light absorption of the fluorescent material is insufficient, but may be omitted when unnecessary. As the light absorbing material, a material that does not quench the fluorescence of the fluorescent material may be selected.

The organic EL device of the present invention is usually used as a DC drive type or pulse drive type EL device, but it can also be driven by AC. The applied voltage is usually 2 to 30
V.

[0106]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention. Example 1 In an organic EL device having a structure as shown in FIG. 1, a hole transport layer 13 as an organic compound was replaced with CuAlS as an inorganic compound.
to produce an organic EL device was replaced by e ₂ thin film.

As a glass substrate, product name 7 manufactured by Corning Incorporated
The 059 substrate was scrub-cleaned using a neutral detergent.

An ITO hole injection electrode layer having a thickness of 200 nm was formed on this substrate at a substrate temperature of 250 ° C. by an RF magnetron sputtering method using an ITO oxide target.

Next, without breaking the vacuum, the substrate temperature was set to 350 ° C., and Cu: Al: Se = 1: 1 in atomic ratio.
Using a target prepared with a composition of 0.9: 2.8, A
A 200 nm thick CuAlSe ₂ thin film was formed by RF magnetron sputtering using r gas.

The composition analysis of the CuAlSe ₂ thin film by X-ray fluorescence analysis revealed that the atomic ratio of Cu: Al: Se = 1.0.
2: 0.92: 1.99. X-ray diffraction revealed that the film was a polycrystalline thin film having a chalcopyrite-type crystal structure. The resistivity of the CuAlSe ₂ thin film is 50 Ωcm, it is a p-type semiconductor film according to the measurement of the Seebeck coefficient, and the band gap is 2.68 from the light transmission characteristics.
eV.

Here, the CuAlSe ₂ thin film was taken out for evaluation, but in actual device fabrication, CuAlSe ₂ thin film was used.
₂ After forming the thin film, the substrate temperature is cooled to room temperature to break the vacuum, and the Alq ³ thin film is
5 nm was formed.

Further, as an electron injection electrode, an AlLi alloy electrode film was formed to a thickness of 50 nm by a sputtering method.
The electrode area was 1 mm ² .

From the obtained structure, electrodes were drawn out of the hole injection electrode and the electron injection electrode using a probe electrode in a vacuum, and an electric field was applied. The VI characteristic shows a diode characteristic. When the ITO side is biased positive and the AlLi side is biased negatively, the current increases as the voltage increases,
At 8 V, an injection current of 0.07 mA was observed, and clear green light emission was observed in a normal room. Further, even when the light emitting operation was repeatedly performed, no decrease in luminance was observed.

Next, the life characteristics were examined at a constant current of 0.05 mA. In exactly the same device evaluation except that the conventional TPD was used as the hole transport layer, the luminance was reduced by half in 100 hours, whereas in this example, 90% of the luminance was maintained in 100 hours.

The reason why excellent life characteristics were obtained by this example is that the hole injection layer was replaced with an organic compound.
It is considered that the use of the chalcopyrite compound as a chemically stable inorganic p-type semiconductor effectively blocked electrons and effectively injected holes into the light emitting layer for a long time and stably. .

Example 2 In the same manner as in Example 1, in the organic EL having the structure shown in FIG. 1, the hole transport layer made of an organic substance was replaced with Cu (Al, G).
a) An organic EL device replaced with an S ₂ epitaxial film was manufactured.

Here, Si was used as the substrate.

First, the inventors' patent application No. 7-21985.
0, ZrO ₂ according to the method of Japanese Patent Application No. 7-24060.
Was produced as follows.

As a single crystal substrate on which a ZrO ₂ thin film was grown, an Si single crystal wafer cut and mirror-polished so that the surface became a (100) plane was used. After the purchase, the mirror surface was cleaned by etching with a 40% ammonium fluoride aqueous solution. Note that a circular substrate having a diameter of 2 inches was used as the Si substrate.

The single crystal substrate was fixed to a substrate holder provided with a rotation and heating mechanism installed in a vacuum chamber, and the vacuum chamber was evacuated to 10 ⁻⁶ Torr by an oil diffusion pump. To protect with a material,
Rotate at 0 rpm, oxygen is supplied from the nozzle near the substrate by 25 cc.
/ Minute while heating at 600 ° C. Here, a Si oxide film is formed on the surface of the substrate by thermal oxidation.
By this method, a Si oxide film of about 1 nm was formed.

Next, the substrate was heated to 900 ° C. and rotated. The rotation speed was 20 rpm. At this time,
By introducing oxygen gas from the nozzle at a rate of 25 cc / min and evaporating metal Zr from the evaporation source onto the substrate,
It was supplied so as to have a thickness of 5 nm in terms of the thickness of the Zr metal oxide, to obtain a Si surface-treated substrate having a 1 × 1 surface structure.

Further, metal Zr was supplied from the evaporation source onto the Si surface-treated substrate while the substrate temperature was 900 ° C., the substrate rotation speed was 20 rpm, and oxygen gas was introduced from the nozzle at a rate of 25 cc / min. _Two epitaxial films were obtained on the processing substrate.

Subsequently, the substrate on which ZrO ₂ was formed
Heated to 00 ° C. and rotated. The rotation speed was 20 rpm.
The degree of vacuum was evacuated to 10 ^-7 Torr by an oil diffusion pump.

The atomic ratio of Cu: Ga: S =
1: 0.95: 5, Cu is an electron beam, G
a, S is evaporated using a K cell to form a 200 nm thick CuG
An aS ₂ thin film was formed.

As a result of RHEED observation, it was found that the CuGaS ₂ thin film was an epitaxial film. Also, CuA
The resistivity of the lSe ₂ thin film was 0.1 Ωcm.

Further, the atomic ratio of Cu: Al: Ga: S =
In a ratio of 1: 0.70: 0.25: 5, Cu and Al are electron beams, Ga and S are evaporated using a K cell, and the film thickness is 5
A 0 nm Cu (Al, Ga) S ₂ thin film was formed.

As a result of the RHEED observation, Cu (Al, G
a) The S ₂ thin film was found to be an epitaxial film. The resistivity of this thin film was 50 Ωcm, and it was found from the measurement of the Seebeck coefficient that it was a p-type semiconductor film, and the bandgap was 3.12 eV from the light transmission characteristics.

Here, the thin film was taken out for evaluation of the thin film. However, in the actual device fabrication, after the thin film was formed, the substrate was cooled to room temperature to break the vacuum, and the Alq ³ thin film was formed by an evaporation method using resistance heating. Was formed to a thickness of 35 nm.

Further, as an electron injection electrode, an AlLi alloy electrode film was formed to a thickness of 50 nm by a sputtering method.
The electrode area was 1 mm ² .

From the obtained structure, the electrodes were pulled out from the CuGaS ₂ thin film and the AlLi alloy electrode film using a probe electrode in a vacuum, and an electric field was applied. The VI characteristics show diode characteristics, with the CuGaS ₂ thin film side plus,
When the i-side was negatively biased, the current increased with increasing voltage, an injection current of 0.1 mA was observed at 10 V, and clear green light emission was observed in a normal room. Further, even when the light emitting operation was repeatedly performed, no decrease in luminance was observed.

Next, the life characteristics were examined at a constant current of 0.05 mA. In the device evaluation of the conventional example described in Example 1 using the conventional TPD as the hole transport layer, the luminance was reduced by half in 100 hours, whereas in the present example, it was almost 10% in 100 hours.
The brightness of 0% was maintained.

The reason why excellent life characteristics were obtained by this example is that the hole injection layer was replaced with an organic compound.
By using chalcopyrite compound in the form of epitaxial thin film as a chemically stable inorganic p-type semiconductor,
This is considered to be because electrons were blocked and holes were injected into the light emitting layer effectively and stably for a long time.

[0133]

As described above, according to the present invention, it is possible to provide an organic EL device having both the advantages of an organic material and an inorganic material, a long life, improved efficiency, and a low operating voltage.

Further, it is possible to provide an organic EL device having a large practical value particularly for a high-performance flat type color display.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of an organic EL device of the present invention.

FIG. 2 is a schematic sectional view showing another configuration example of the organic EL device of the present invention.

FIG. 3 is a cross-sectional view of an organic EL device having a two-layer structure having a hole transport layer.

FIG. 4 is a cross-sectional view of an organic EL device having a three-layer structure having a hole transport layer and an electron transport layer.

FIG. 5 is a band diagram of a conventional organic EL device having a two-layer structure.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 hole injection electrode 3 electron injection electrode 4 inorganic layer 5 light emitting layer 11 substrate 12 hole injection electrode 13 electron injection electrode 14 hole transport layer 15 light emitting layer 16 electron transport layer

Claims (3)

[Claims] 1. An organic EL having a structure in which at least an inorganic layer containing a chalcopyrite compound or a modified chalcopyrite compound and a light emitting layer containing at least an organic compound involved in a light emitting function are laminated on a substrate. element. 2. The band gap of said inorganic layer is 2.5.
2. The organic EL device according to claim 1, which is eV or more. 3. The organic EL device according to claim 1, wherein said inorganic layer is a p-type semiconductor.