JPH05202357A - Organic electroluminescence element - Google Patents

Abstract

PURPOSE:To provide the subject element capable of emitting blue light in high brightness by laminating an anode, a hole transfer layer, a luminous layer containing a pyrimidopyrimidine derivative and a cathode in the order. CONSTITUTION:An anode, a hole transfer layer comprising an organic compound, a luminous layer (the layer contains an electron-transferring organic host substance, and the atom ratio of the host substance is larger than the atom ratio of a pyrimidopyrimidine derivative) containing the pyrimidopyrimidine derivative of formula I [R1 to R4 are H, halogen, group of formula II (R5, R6 are H, alkyl, etc., or R5, R6 are atom or group for together forming a cycloalkyl or heterocyclic group)] [e.g. tri(p-methoxyanilino) pyrimido[5,4-d]pyrimidine], and a cathode are successively laminated to each other to provide the objective element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device provided with a light emitting layer in which such a substance is formed into a layer by utilizing the electroluminescence of a substance which emits light when an electric current is injected, and particularly the light emitting layer emits an organic compound. The present invention relates to an organic electroluminescence element configured as a body (hereinafter referred to as an organic EL element).

[0002]

2. Description of the Related Art As an organic EL device of this type, as shown in FIG. 1, a phosphor thin film 3 made of an organic compound, that is, a light emitting layer and a positive electrode layer, are laminated between a metal cathode 1 and a transparent anode 2. A two-layer structure in which the hole transport layer 4 is arranged, or an electron transport layer 5 made of an organic compound laminated between the metal cathode 1 and the transparent anode 2 as shown in FIG.
A three-layer structure having a light emitting layer 3 and a hole transporting layer 4 is known. Here, the hole transport layer 4 has a function of facilitating the injection of holes from the anode (hole transport property) and a function of blocking electrons, and the electron transport layer 5 is a function of facilitating the injection of electrons from the cathode. It has an electron transporting property.

In these organic EL devices, the transparent anode 2
A glass substrate 6 is disposed on the outer side of, and excitons are generated by recombination of electrons injected from the metal cathode 1 and holes injected from the transparent anode 2 to the light emitting layer 3, and the excitons emit Light is emitted in the process of deactivation, and this light is emitted to the outside through the transparent anode 2 and the glass substrate 6. Furthermore, FIG.
An organic EL device having a two-layer structure shown in (3) and having stable light emission by forming the light emitting layer 3 from an electron transporting organic host substance and a fluorescent guest substance has also been developed.

[0004]

However, in the conventional organic EL element of the organic compound having the above-mentioned structure, an organic EL element which emits blue light with higher brightness is desired. An object of the present invention is to provide an organic EL device capable of emitting blue light with high brightness.

[0005]

The organic EL device according to the present invention comprises:
A positive electrode, a hole transport layer made of an organic compound, a light emitting layer made of an organic compound, and a cathode are laminated in this order, and the light emitting layer is a pyrimidopyrimidine derivative represented by Chemical Formula 1.

[0006]

[Chemical 1]

{In the chemical formula 1, R ₁ , R ₂ , R _{3 and} R ₄ each independently represent a hydrogen atom, a halogen atom or a group represented by the chemical formula 2,

[0008]

[Chemical 2]

In the chemical formula 2, R _{5 and} R ₆ are each independently a hydrogen atom, an alkyl group, an aryl group, or an atom in which R ₅ and R ₆ are taken together to complete a cycloalkyl group or a heterocyclic group. Or represents a group}.

[0010]

The present invention will be described below with reference to the drawings. The organic EL element of the present invention is similar to the organic EL element having the structure shown in FIGS. 1 and 2, and as shown in FIG. 1, a light emitting layer 3 and a light emitting layer 3 are provided between a pair of metal cathode 1 and transparent anode 2. Hole transport layer 4
Is laminated and formed as a thin film, or as shown in FIG. 2, an electron transport layer 5, a light emitting layer 3 and a hole transport layer 4 are formed between a pair of metal cathode 1 and transparent anode 2. The structure is fine. In either case, one of the electrodes 1 and 2 may be transparent. For example, the cathode 1 is made of an alkaline earth metal such as aluminum and magnesium, an alkali metal such as indium, silver and lithium, or a metal having a small work function such as an alloy of each and having a thickness of about 100 to 5000 Å. obtain. Further, for example, the anode 2 is made of a conductive material having a large work function such as indium tin oxide (hereinafter referred to as ITO) and has a thickness of about 1000 to 3000 Å, or gold with a thickness of about 800 to 1500 Å. Can be used. When gold is used as the electrode material, the electrode becomes semitransparent.

The light-emitting layer 3 has a pyrimido [5,4-d] pyrimidine (Pyrimido [5,4]
-d] Pyrimidine) having a skeleton of pyrimidopyrimidine). R ₅ and R _{6 in} Formula 2 are each independently a hydrogen atom, an alkyl group, an aryl group, or R ₅
And R ₆ are preferably atoms or groups which together form a cycloalkyl group or a heterocyclic group, so that R _{1 to} R ₄ in the pyrimidopyrimidine derivative of the above Chemical Formula 1 are each independently added. In addition, it has a hydrogen atom, a halogen atom and a set of the above chemical formula 2. For example,
Such a group is a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, a diethanolamino group (diethanolamino),
Ethanolamino group (ethanolamino), piperidino group (pip
eridino), p-methoxyanilino group (p-methoxyanlino), m
-Methoxyanilino group, morpholino group
(morpholino), anilino group (anilino), benzylamino group (benzylamino), diphenylamino group (diphenylamin)
o), pyrrolidino group, piperidino group (pipe
ridino), a thiazolidino group and a thiomorpholino group.

As described above, typical heteroatoms contained in the heterocyclic group of the above chemical formula 2 in the pyrimidopyrimidine derivative of the above chemical formula 1 include nitrogen, oxygen, sulfur and the like. Further, the various alkyl groups, alkylene groups, aryl groups and arylene group moieties of the above chemical formula 2 may be substituted, respectively. Representative of such substituents include alkyl groups, alkoxy groups, aryl groups, aryloxy groups and halogen atoms such as fluorine, chlorine and bromine.

Further, for example, the pyrimidopyrimidine derivative has a structure represented by the chemical formula 3.

[0014]

[Chemical 3]

{In the chemical formula 3, R _{1 and} R ₂ are different from each other, and each is a hydrogen atom, a halogen atom, or the chemical formula 2
Which represents a group represented by

[0016]

[Chemical 4]

{In the chemical formula 4, R _{5 and} R ₆ are each independently a hydrogen atom, an alkyl group, an aryl group, or R ₅ and R ₆ are taken together to complete a cycloalkyl group or a heterocyclic group. It represents an atom or a group}. Specific examples of the pyrimidopyrimidine derivative include dipyridamole (Dipyridamo
There is a substance called le), which can be contained in the light emitting layer 3 to form an organic EL device. Dipyridamole (2,6-bis (diethanolamino) -4,8-didiperidino Pyrimid
o [5,4-d] Pyrimidine) is represented by Chemical Formula 5.

[0018]

[Chemical 5]

This dipyridamole is pyrimido [5,
The 4-d] pyrimidine skeleton has a diethanolamino group at the 2,6-position and a piperidino group at the 4,8-position.
peridino) and has the structure represented by the above chemical formulas 3 and 4. Other pyrimidopyrimidine derivatives include, for example, tri (p-methoxyanilino) represented by the chemical formula 6.
Pyrimido [5,4-d] pyrimidine {2,4,8-tri (p-met
hoxyanlino) Pyrimido [5,4-d] Pyrimidine},

[0020]

[Chemical 6]

2,4,6,8-tetramorpholinopyrimido [5,4-d] pyrimidine represented by the chemical formula 7 {2,4,6,8-t
etramorpholino Pyrimido [5,4-d] Pyrimidine},

[0022]

[Chemical 7]

2,4,6,8-tetraanilinopyrimido [5,4-d] pyrimidine represented by the chemical formula 8 {2,4,6,8-tet
raanilino Pyrimido [5,4-d] Pyrimidine},

[0024]

[Chemical 8]

2,4,6,8-tetra (p-
Methoxyanilino) pyrimido [5,4-d] pyrimidine {2,4,6,8-tetra (p-methoxyanlino) Pyrimido [5,4-d] P
yrimidine},

[0026]

[Chemical 9]

2,4,6,8-tetrabenzylaminopyrimido [5,4-d] pyrimidine represented by the chemical formula 10 {2,4,
6,8-tetrabenzylamino Pyrimido [5,4-d] Pyrimidin
e},

[0028]

[Chemical 10]

2,4,8-trimorpholinoaminopyrimido [5,4-d] pyrimidine represented by the chemical formula 11 {2,4,8
−trimorpholino Pyrimido [5,4-d] Pyrimidine},

[0030]

[Chemical 11]

2,4,8-tripyrrolidinopyrimido [5,4-d] pyrimidine represented by the chemical formula 12 {2,4,8-tri
pyrrolidino Pyrimido [5,4-d] Pyrimidine},

[0032]

[Chemical 12]

2,4,8-Tetrapiperidinopyrimido [5,4-d] pyrimidine represented by the chemical formula 13 {2,4,6,8-t
etrapiperidino Pyrimido [5,4-d] Pyrimidine},

[0034]

[Chemical 13]

2,4,8-tetrathiomorpholinopyrimido [5,4-d] pyrimidine represented by the chemical formula 14 {2,4,6,
8-tetrathiomorpholino Pyrimido [5,4-d] Pyrimidin
e},

[0036]

[Chemical 14]

There are, for example, It is possible to form a two-layer or three-layer organic EL device by using only the above-mentioned pyrimidopyrimidine derivative for the light emitting layer 3. In addition, the light emitting layer 3 is 2
In the layer structure, the pyrimidopyrimidine derivative may be formed as a small amount of a fluorescent guest substance by mixing with a large amount of an electron transporting organic host substance.

The host material of the light emitting layer 3 is t-Bu-PBD {2- (4'-tert-Butylphenyl) -5- which will be described later.
(biphenyl) -1,3,4-oxadiazole} and tris (8-quinolinol) aluminum of the following chemical formula 15

[0039]

[Chemical 15]

It is preferable to use quinoline derivatives such as Other quinoline derivatives include, for example, bis (8-quinolinol) magnesium and bis (benzo {f} -8-
Quinolinol) zinc, bis (2-methyl-8-quinolinol) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8-). Quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, and poly [zinc (II) -bis (8-hydroxy-5-).
Quinolinyl) methane].

As described above, the above pyrimidopyrimidine derivative is used as the guest substance in the light emitting layer. In this case, it is preferable that the atomic ratio of the electron-transporting organic host material is higher than that of the pyrimidopyrimidine derivative as the fluorescent guest material. Here, the pyrimidopyrimidine derivative of the guest substance is, for example, t-Bu-PB of the host substance.
It is preferable that the light emitting layer of D contains 1% or less of concentration or atomic ratio. This is because light emission with high brightness can be obtained with a low applied voltage.

Next, in the hole transport layer 4, a tetraphenyldiamine derivative (hereinafter referred to as TPD), for example, N, N'-diphenyl- represented by the following chemical formula 16 is shown.
N, N'-bis (3methylphenyl) -1,1'-biphenyl-4,4'-diamine is preferably used, and CTM (Carrier Transporting) of the following chemical formulas 17 to 27 is used.
The compounds known as Materials) can be used alone or as a mixture.

[0043]

[Chemical 16]

[0044]

[Chemical 17]

[0045]

[Chemical 18]

[0046]

[Chemical 19]

[0047]

[Chemical 20]

[0048]

[Chemical 21]

[0049]

[Chemical formula 22]

[0050]

[Chemical formula 23]

[0051]

[Chemical formula 24]

[0052]

[Chemical 25]

[0053]

[Chemical formula 26]

[0054]

[Chemical 27]

Further, in the above embodiment, the light emitting layer 3 and the organic hole transport layer 4 are arranged between the cathode 1 and the anode 2 to have a two-layer structure, but as shown in FIG. The same effect can be obtained as an organic EL device having a three-layer structure in which the organic electron transport layer 5 made of the perylene tetracarboxylic derivative represented by the following chemical formula 33 is arranged. Further, the electron transport layer 5
Is the above-mentioned t-Bu-indicated by the following chemical formula 28:
PBD is preferably used, and the following chemical formulas 29 to 3 are used.
The compound represented by 9 can also be used.

[0056]

[Chemical 28]

[0057]

[Chemical 29]

[0058]

[Chemical 30]

[0059]

[Chemical 31]

[0060]

[Chemical 32]

[0061]

[Chemical 33]

[0062]

[Chemical 34]

[0063]

[Chemical 35]

[0064]

[Chemical 36]

[0065]

[Chemical 37]

[0066]

[Chemical 38]

[0067]

[Chemical Formula 39]

Specifically, an EL device having a light emitting layer containing dipyridamole was prepared. (Example 1) Including dipyridamole as a guest substance
EL device having a light emitting layer First, a plurality of ITO thin films in a strip shape (2 mm
The glass substrate with ITO formed in the width) was prepared, and this was ultrasonically cleaned for 5 minutes in a mixture of isopropyl alcohol and distilled water (1: 1, volume ratio). The washed substrate is then rinsed well in ethyl alcohol, dried with toluene vapor and placed in an oven at 75 ° C for 2 hours.
Hold for 0 minutes to dry.

Next, using the vapor deposition apparatus, this dried I
The TPD of the above chemical formula 16 was placed on a TO glass substrate in a tantalum boat, and TPD was vacuum-deposited to a film thickness of 500 Å to form a hole transport layer. Then, t-Bu-PBD of the above Chemical Formula 28 and dipyridamole of the above Chemical Formula 5 are formed on the hole transport layer of TPD by a two-source evaporation method.
It was vacuum-deposited using a rce evaporation technique) to form a light emitting layer. That is, t-Bu-PBD and dipyridamole were co-evaporated from two boats while adjusting the vapor deposition rate so as to obtain a desired composition with two monitors. Here, a light emitting layer made of these mixtures was formed to a thickness of 500Å at a rate such that t-Bu-PBD had a deposition rate of 500Å / sec and dipyridamole had a deposition rate of 10Å / sec.

Next, 0.2 cm × 3 cm is formed on the mixed light emitting layer.
A rectangular mask shadow mask is placed, and Mg and Al are vacuum-deposited by a two-source vapor deposition method so as to have a composition atomic ratio of 10: 1 and a film thickness of 2500Å to form an electrode, and then the two-layer structure E shown in FIG.
An L element was created. In addition, regarding the obtained EL element, response characteristics of current and luminance with respect to voltage (IV-L characteristics)
Was measured. A positive voltage was applied to the ITO electrode and the Mg-Al electrode was connected to the ground via an ammeter. The light emitted from the EL device cell was detected by a photometer. The cell started to emit light at about 6V, 219 cd / m ² , 0.0139 lm / w at 15V.
And the device breakdown occurred at about 16V (FIG. 3).

The emission spectrum of the obtained EL device was measured. The spectrum shape of the electroluminescence (EL) emission light of the EL device was observed with a photometer (Fig. 4a). The spectral shape of the photoluminescence (PL) emission light of dipyridamole in dioxane solution was also observed with a photometer (Fig. 4b). E of the EL device obtained here
Since the L emission spectrum shape and the peak wavelength coincided with those of the PL emission spectrum of dipyridamole in the dioxane solution, it was confirmed that dipyridamole emission was performed in this device. (Examples 2 to 9) Guess various pyrimidopyrimidine derivatives
An EL device having a light emitting layer containing as an ITO substance An ITO glass substrate similar to that in Example 1 except that each of the pyrimidopyrimidine derivatives represented by the above Chemical Formulas 6 to 13 was used as a guest substance in Examples 2 to 9, TPD
An EL device composed of the hole transport layer, t-Bu-PBD, the hole transport layer of each guest substance, and the Mg-Al electrode was prepared. Luminous properties such as luminance L, luminous efficiency η, and current density I as shown in Table 1 are shown.

Table 1 EL device L (cd / m ² ) η (lm / w) I (A / cm ² ) Example 2 23 0.0103 0.070 Example 3 130 0.0548 0.039 Example 4 41 0.0158 0.047 Example 5 31 0.0643 0.0058 Example 6 13 0.00263 0.1033 Example 7 110 0.0193 0.0813 Example 8 149 0.0124 0.2782 Example 9 54 0.0392 0.0221 The emission spectrum distributions of the organic EL devices of Examples 2-9 are shown in FIGS. 5-12, a and b
The figure shows the spectrum distribution of the EL emission light of the EL device itself and the spectrum distribution of the pyrimidopyrimidine derivative PL emission light represented by the chemical formulas 6 to 13 in the dioxane solution.

Since the EL spectra of Examples 2 to 9 are the same as or similar to the PL spectra of the various pyrimidopyrimidine derivatives used as the guest substances, as shown in FIGS. It was confirmed that light emission of various pyrimidopyrimidine derivatives occurred in the light emitting layer of each device. Example 10 Having a light emitting layer containing only dipyridamole
EL device as described in Example 1 T on a glass substrate with ITO as described in Example 1.
Dipyridamole was vapor-deposited to a thickness of 500 Å on the PD vapor-deposited to a thickness of 500 Å. On this, Mg-Al was vapor-deposited to a film thickness of 2000 Å in the same manner as in Example 1.

The I-V-L characteristic of the obtained EL device was measured in the same manner as in Example 1. When the light-emitting property was measured, a pale light emission was confirmed at about 15V. further,
In order to make another example, 2,6-dimorpholino-4,8-dipiperidinopyrimides represented by the following formulas 40 to 44, which are contained in the pyrimidopyrimidine derivative of the above formula 1, are included.
[5,4-d] pyrimidine (2,6- (Dimorphorino-4,8-dipiperid
ino Pyrimido [5,4-d] Pyrimidine), 2,6-bis (hydroxyethylmethylamino) -4,8-dipiperidinopyrimide
[5,4-d] pyrimidine (2,6-bis (hydroxyethyl-methyl-ami
no) -4,8-dipiperidino Pyrimido [5,4-d] Pyrimidine),
2,6-bis (hydroxyethylmethylamino) -4,8-dithiomorpholinopyrimido [5,4-d] pyrimidine (2,6-bis (hyd
roxyethyl-methyl-amino) -4,8-dithiomorphorino Pyrim
ido [5,4-d] Pyrimidine), 2,6-bis (hydroxyethylmethylamino) -4,8-dimorpholinopyrimido [5,4-d] pyrimidine (2,6-bis (hydroxyethyl-methyl- amino) -4,8-dim
orphorino Pyrimido [5,4-d] Pyrimidine), 2,6-bis (hydroxyethylmethylamino) -4,8-dipyrrolidinylpyrimido [5,4-d] pyrimidine (2,6-bis (hydroxyethy)
l-methyl-amino) -4,8-dipyrrolidinyl Pyrimido [5,4-d]
Pyrimidine) was prepared.

[0075]

[Chemical 40]

[0076]

[Chemical 41]

[0077]

[Chemical 42]

[0078]

[Chemical 43]

[0079]

[Chemical 44]

Example 11 Pyrimido represented by Chemical Formula 40
Has a light emitting layer containing a pyrimidine derivative as a guest substance
EL device under the same conditions as in Example 1 above.
It has an ITO anode with a thickness of 00Å, a TPD hole transport layer with a thickness of 500Å, and a MgAl cathode with a thickness of 900Å, and further has a t-
A co-deposited thin film comprising Bu-PBD and a pyrimidopyrimidine derivative represented by the chemical formula 40, wherein the deposition rate of t-Bu-PBD is 600Å / sec, and the deposition rate of the pyrimidopyrimidine derivative is 1.5Å / sec, 3Å / sec, 3.75Å / sec, 4.
Six two-layer structure EL devices having the light emitting layer 9 having a film thickness of 600 Å which was changed to 5 Å / sec, 35 Å / sec and 52 Å / sec were prepared.

I-V-L characteristics of the obtained EL device
Was measured. Table 2 shows the resulting brightness L, luminous efficiency η, and electricity.
The light emission characteristic of pressure V is shown.Table 2 Pyrimidopyrimidine derivative Concentration (Å / sec) η (lm / w) * L (cd / m ² ) ** V (V) ** 1.5 0.26 17.05 13.18 3 0.21 19.10 11.62 3.75 0.18 16.70 14.39 4.5 0.22 26.73 13.44 35 0.21 38.90 7.1652 0.26 62.38 9.35 * 10^-3A / cm²Hour ** 10^-3A / 4mm²As is clear from Table 2, when the guest substance concentration changes,
Even if the emission spectrum changes drastically, the luminous efficiency is
Almost the same, but the brightness increased significantly. That is injected
The number of electrons and holes is not affected by the guest substance concentration
However, the rate at which electrons and holes recombine and emit light in the molecule is
It increases with increasing material concentration, which is
It can be seen that it causes an increase in brightness at the flow rate.
It

Then, the emission spectrum of the obtained EL device was measured. The spectral shape of the EL emission light of the EL device was observed with a photometer. When the guest substance concentration is as low as 1.5 Å / sec, a peak of wavelength 470 nm appears next to the peak of wavelength 400 nm, and as the concentration of guest substance increases, the peak of wavelength 400 nm becomes lower and the peak of wavelength 470 nm becomes higher, which is dominant. Became. The hue of luminescence changed from blue close to purple to blue close to green. (Examples 12 to 15) Various pyrimidopyrimidine derivatives were prepared.
EL device having a light emitting layer containing it as a guest material In the same manner as in Example 11, except that each pyrimidopyrimidine derivative represented by the above Chemical Formulas 41 to 44 was used as a guest material in Examples 12 to 15, an ITO glass substrate, An EL device including a hole transport layer of TPD, t-Bu-PBD, a hole transport layer of each guest substance, and an MgAl electrode was prepared. Table 3 shows the emission characteristics of guest substance concentration, emission efficiency η, and current-luminance relationship IL.

[0083]Table 3 Guest substance EL element concentration (Å / sec) η (lm / w) IL Example 11 52 0.25 logL = 1.05.logI + 173x10^-6 Example 12 40 0.13 logL = 0.89.logI + 178x10^-6 Example 13 35 0.11 logL = 0.91 * logI + 272x10^-6 Example 14 15 0.09 logL = 0.89.logI + 425x10^-6 Example 15 7 0.04 logL = 1.01.logI + 1091x10 ^-6  Furthermore, each of the pyrimidopyrimidimes used in Examples 11 to 15
10 derivatives^-FourPL emission light as M dioxane solution
The spectral shape of was observed with a photometer. So
Table 4 shows the peak wavelength and its intensity, respectively.

Table 4 EL device Peak wavelength (nm) Intensity (eV) Example 11 470 4055 Example 12 473 3586 Example 13 482 3559 Example 14 479 3644 Example 15 461 4079

[0085]

As described above, since the organic EL device according to the present invention has the light emitting layer containing the pyrimidopyrimidine derivative represented by the above chemical formula 1, it can emit blue light with high brightness at a low applied voltage. Further, according to the present invention, the luminous efficiency of the organic EL element is improved, the emission spectrum distribution is sharpened, and the color purity of the emitted color is improved.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an organic EL device having a two-layer structure.

FIG. 2 is a structural diagram showing an organic EL device having a three-layer structure.

FIG. 3 is a graph of response characteristics of current and luminance with respect to voltage of the organic EL device of Example 1.

FIG. 4 is an EL spectrum distribution (a) of the organic EL device of Example 1 and a PL spectrum distribution (b) of its guest molecule.
Is.

FIG. 5 is an EL spectrum distribution (a) of the organic EL device of Example 2 and a PL spectrum distribution (b) of its guest molecule.
Is.

FIG. 6 is an EL spectrum distribution (a) of the organic EL device of Example 3 and a PL spectrum distribution (b) of its guest molecule.
Is.

FIG. 7: EL spectrum distribution (a) of the organic EL device of Example 4 and PL spectrum distribution (b) of its guest molecule.
Is.

8 is an EL spectrum distribution (a) of the organic EL device of Example 5 and a PL spectrum distribution (b) of its guest molecule. FIG.
Is.

FIG. 9 is an EL spectrum distribution (a) of the organic EL device of Example 6 and a PL spectrum distribution (b) of its guest molecule.
Is.

10 is an EL spectrum distribution (a) of the organic EL device of Example 7 and a PL spectrum distribution (b) of its guest molecule. FIG.

11 is an EL spectrum distribution (a) of the organic EL device of Example 8 and a PL spectrum distribution (b) of its guest molecule. FIG.

FIG. 12 is an EL spectrum distribution (a) of the organic EL device of Example 9 and a PL spectrum distribution (b) of its guest molecule.

[Explanation of symbols for main parts]

 1 Metal Electrode (Cathode) 2 Transparent Electrode (Anode) 3 Light Emitting Layer 4 Organic Hole Transport Layer 5 Electron Transport Layer 6 Glass Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryushi Murayama 6-1, 1-1 Fujimi, Tsurugashima City, Saitama Pioneer Co., Ltd. (72) Inventor Jun Funaki 6-1, 1-1 Fujimi, Tsurugashima City, Saitama Prefecture Pioneer Research Institute

Claims (7)

[Claims] 1. A positive electrode, a hole transport layer comprising an organic compound,
A light emitting layer made of an organic compound and a cathode are laminated in this order, and the light emitting layer is a pyrimidopyrimidine derivative represented by Chemical Formula 1. {In the chemical formula 1, R ₁ , R ₂ , R _{3 and} R ₄ each independently represent a hydrogen atom, a halogen atom or a group represented by the chemical formula 2, and In Chemical Formula 2, R _{5 and} R ₆ are each independently a hydrogen atom,
An alkyl group, an aryl group, or R ₅ and R ₆ together represent an atom or a group that completes a cycloalkyl group or a heterocyclic group}. 2. The pyrimidopyrimidine derivative is represented by Chemical Formula 3. embedded image The organic electroluminescence device according to claim 1, wherein R _{1 and} R _{2 in} Chemical Formula 3 are different from each other and each represents a hydrogen atom, a halogen atom, or a group represented by the Chemical Formula 2. 3. The pyrimidopyrimidine derivative is represented by Chemical Formula 4. embedded image {In Chemical Formula 4, R _{5 and} R ₆ are each independently a hydrogen atom, an alkyl group, an aryl group, or an atom or a group in which R ₅ and R ₆ are taken together to complete a cycloalkyl group or a heterocyclic group. Is represented}. The organic electroluminescence device according to claim 1, wherein 4. The organic electroluminescence device according to claim 1, wherein the hetero atom contained in the heterocyclic group is nitrogen, oxygen or sulfur. 5. In the pyrimidopyrimidine derivative, the hydrogen atom in the alkyl group, the aryl group, the alkylene group, and the arylene group in the group represented by the chemical formula 2 is an alkyl group, an alkoxy group, an aryl group, or an aryloxy group. Alternatively, the organic electroluminescence device according to any one of claims 1 to 4, wherein the organic electroluminescence device is substituted with a halogen atom. 6. The light-emitting layer contains an electron-transporting organic host material, and the atomic ratio of the electron-transporting organic host material is higher than the atomic ratio of the pyrimidopyrimidine derivative. The organic electroluminescent element according to claim 1. 7. The organic electroluminescence device according to claim 1, further comprising an organic electron transport layer disposed between the cathode and the light emitting layer.