JP2003068448A - Organic el element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide new moisture proof film, which prevents invasion of moisture and oxygen into an organic EL element. SOLUTION: In at least a part of an exposed surface of a thin film organic EL element, the moisture proof film, which consists of SiMx Oy (M is at least one kind of element chosen from the group which consists of C, N, and B, and it is 0.05<=x<=0.5, and is 1.5<=y<=1.95), is provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to organic electroluminescence (EL). More specifically, the present invention relates to a moisture-proof film for organic EL.

[0002]

2. Description of the Related Art Research and development have been conducted on organic EL as a next-generation display element. Organic EL is a promising display device in the future because it emits light by itself, has high brightness, and consumes low power.

However, the organic material used for the organic EL has a weak resistance to moisture, which poses a serious problem in practical use. In addition, the characteristics of the electrode provided on the organic solid layer are likely to deteriorate due to oxidation. Therefore, conventional organic EL
When the device is driven in the atmosphere, the light emission characteristics deteriorate rapidly. Therefore, in order to obtain a practical organic EL element or organic EL device, the element is sealed so that moisture or oxygen does not enter the organic solid layer and the electrode is not oxidized, thereby extending the life of the element. It is necessary to plan.

As a method of sealing an organic EL, a film thickness of 0.1
A method of providing a para-xylene thin film having a thickness of up to 20 μm on an organic EL element by a vapor phase polymerization method, or a method of providing an organic material film such as polybutadiene or an inorganic material film such as SiO ₂ on the organic EL element by a vapor deposition method or a sputtering method. However, the sealing by these methods is still insufficient.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel moisture-proof film which prevents moisture and oxygen from entering the organic EL device.

[0006]

[Means for Solving the Problems] The above-mentioned problems are the thin film organic E
SiM _x O on at least a part of the exposed surface of the L element
_y (provided that M is at least one element selected from the group consisting of C, N and B, and 0.05 ≦ x ≦ 0.5 and 1.5 ≦ y ≦ 1.95) It is solved by providing a moisture-proof film.

[0007]

FIG. 1 is a schematic sectional view of an example of an organic EL device according to the present invention. I on one upper surface of the glass substrate 3
A TO (indium tin oxide) electrode 5 is deposited,
A three-layer structure layer composed of a hole transport layer 9 and an electron transport layer 11 sandwiching the light emitting layer 7 in a sandwich shape is provided on the upper surface of the electrode 5, and a back electrode 13 is deposited on the upper surface of the electron transport layer 11. Let The ITO electrode 5 and the back electrode 13 are connected to the power supply 15. In the organic EL device according to the present invention, the organic EL element 1 is an optically transparent moisture-proof film 1 at the outermost peripheral portion in contact with the outside air.
Have 7.

The moisture-proof film 17 is made of SiM _x O _y (where M is at least one element selected from C, N and B, and 0.05 ≦ x ≦ 0.5 and 1.5 ≦ y ≦ 1.9
5)). By adding carbon, nitrogen or boron to the material for forming the moisture-proof film, a moisture-proof film having better resistance to bending than a simple SiO ₂ film can be obtained.

Silicon as an inorganic protective film for hard disks
Oxide (SiO_xHowever, for 1.5 ≦ x ≦ 2.0)
Is disclosed in JP-A-6-12568.
It However, thin-film organic E to which external force such as expansion and contraction or bending is applied
For L element, SiO_xThe protective film is mixed by these external forces.
B-like cracking occurs. We have solved this problem
In order to improve the elasticity of silicon oxide,
I, SiM_xO_y(However, M is a small number selected from C, N and B.
At least one element, if 0.05 ≦ x ≦ 0.5
And a protective film consisting of 1.5 ≦ y ≦ 1.95)
Conventional SiO_xExhibits higher elasticity and flexibility than
I discovered that. Therefore, SiM_xO _yThe protective film is a thin film
It can also be applied to organic EL devices.

The compounding amount of M in the SiM _x O _y moisture-proof film of the present invention is preferably in the range of 0.05 ≦ x ≦ 0.5. When x is less than 0.05, the moisture-proof film does not exhibit flexibility. On the other hand, when x exceeds 0.5, the moisture-proof film is excessively hardened and loses flexibility. The amount of M is 0.1 ≦ x ≦
More preferably, it is within the range of 0.2.

The compounding amount of O in the SiM _x O _y moisture-proof film of the present invention is preferably within the range of 1.5 ≦ y ≦ 1.95. When the value of y is less than 1.5, sufficient hardness of the moisture-proof film cannot be obtained. On the other hand, when the value of y exceeds 1.95, the oxygen content becomes excessive and the moisture-proof film becomes brittle.

The thickness of the SiM _x O _y moisture-proof film 17 of the present invention is preferably in the range of 10 nm to 50 nm. When the film thickness of the moisture-proof film 17 is less than 10 nm, sufficient coverage cannot be obtained. On the other hand, when the film thickness of the moisture-proof film 17 exceeds 50 nm, the moisture absorption effect is saturated, which is uneconomical.

SiM of the present invention_xO_yMoisture-proof film 17 is plasm
The film can be formed by the CVD method. Plasma CV
The D method has a higher molecular directivity than the vacuum evaporation method or the sputtering method.
Since it is low, it has excellent throwing power, is dense and has no defects.
A thin film is obtained. Used for film formation by plasma CVD method
The monomer gas used is SiH for Si-C-O. _Four
And O_TwoMixed with vaporizable hydrocarbons, RvH_Three-V
Si-O-SiH_Three-VRv (provided that R has 1 to 6 carbon atoms)
And v is an integer of 1 to 3) and O_TwoTo
Mixture, Si (OCH_Three)_FourOr Si (OC_Two
H₅)_FourAnd O_TwoYou can use a mixture of
SiH for Si-NO_FourAnd O_TwoTo N_TwoTo
Mixed, RvH_Three-VSi-O-SiH_Three-VR
v (provided that R is a hydrocarbon having 1 to 6 carbon atoms, and v is 1
~ Is an integer of 3) and O_TwoTo N_TwoA mixture of Si,
(OCH_Three)_FourOr Si (OC_TwoH₅)_FourAnd O_TwoTo N
_TwoA mixture of Si and B can be used.
For -O, SiH_FourAnd O _TwoTo B_TwoH₆Mixed
Tata, RvH_Three-VSi-O-SiH_Three-VRv (however
R is a hydrocarbon having 1 to 6 carbon atoms, and v is 1 to 3
Is an integer) and O_TwoTo B_TwoH₆A mixture of Si,
(OCH_Three)_FourOr Si (OC_TwoH₅)_FourAnd O _TwoTo B
_TwoH₆A mixture of can be used.

He, Ne, and
Hydrogen (H ₂ ) is added to Ar and Kr or their inert gas, and the total pressure is controlled to 5 to 200 mTorr. 10 kHz to 13.56 for plasma generation
The alternating current of MHz may be used alone, or microwaves (2.54 GHz) may be used together with these alternating currents.

The SiM _x O _y moisture-proof film 17 of the present invention is formed by, for example, a module in which the ITO electrode 5, the hole transport layer 9, the light emitting layer 7, the electron transport layer 11 and the back electrode 13 are formed on the glass substrate 3. Is placed in a deposition chamber of a plasma CVD apparatus (not shown), a deposition gas is fed into the chamber, and high frequency is applied to generate plasma. The film forming process itself by such a plasma CVD method is known to those skilled in the art, and further explanation is not necessary.

As shown in FIG. 2, the moisture-proof effect can be further enhanced by further providing an additional thin film 19 which is optically transparent and hygroscopic on the SiM _x O _y moisture-proof film 17. As such a material, non-magnetic NaCl type CoO or NiO is used.
Thin films are suitable. These materials have a high affinity with water, so that they react with moisture in the atmosphere to form hydroxides and form a dense film. By using the SiM _x O _y film in combination with this dense and transparent film, the moisture-proof effect can be further enhanced. The thickness of the nonmagnetic NaCl type CoO or NiO thin film is preferably in the range of 10 to 50 nm. If the thickness of the additional thin film is less than 10 nm, sufficient hygroscopicity cannot be obtained, while if it exceeds 50 nm, the hygroscopic effect is saturated. The additional thin film can be formed by, for example, a radio frequency (RF) sputtering method. For example, in the case of a CoO film, Co
Target and O ₂ pressure of 5 × 10 ⁻⁴ Torr
RF in a total atmosphere of 5 × 10 ⁻³ Torr including r
Obtained by sputtering.

The organic EL device is usually formed on a glass substrate, but it may be formed on a flexible transparent film. In this case, by covering the entire organic EL element including the flexible transparent film substrate with the SiM _x O _y moisture-proof film 17 of the present invention, the moisture resistance of the flexible organic EL element can be enhanced.

[0018]

EXAMPLES The present invention will be more specifically illustrated by the following examples. (1) Fabrication of organic EL device I on a glass substrate of 50 mm × 50 mm × 1 mm size
A TO film having a thickness of 100 nm was used as a transparent supporting substrate. The transparent supporting substrate was ultrasonically cleaned with isopropyl alcohol for 30 minutes, then with pure water for 30 minutes, and finally with isopropyl alcohol again. Ultrasonic cleaning was performed for a minute. The transparent supporting substrate after cleaning was fixed to a substrate holder of a vacuum vapor deposition apparatus, and N, N'-diphenyl-N, N'-bis- (3-methylphenyl)-[1,1'- was placed in a molybdenum resistance heating boat. Biphenyl] -4,4'-diamine (hereinafter referred to as TPD) was placed in an amount of 200 mg, and another molybdenum resistance heating boat was charged with 200 mg of tris (8-quinolinol) aluminum (hereinafter referred to as Alq) in a vacuum chamber of 1 ×. The pressure was reduced to 10 ⁻⁶ Torr. Next, the resistance heating boat containing TPD
Heat up to 0 ° C and deposit TPD at a deposition rate of 0.1 to 0.3 nm /
s to deposit on the ITO film to form a hole injection layer having a film thickness of 60 nm. The substrate temperature at this time was room temperature. Next, the light-emitting layer was formed subsequent to the formation of the hole-injection layer without taking out the transparent support substrate on which the hole-injection layer was formed, from the vacuum chamber. The light emitting layer is formed by heating the resistance heating boat containing Alq to 275 ° C.
q was deposited on the hole injection layer at a vapor deposition rate of 0.1 to 0.2 nm / s to form an Alq layer having a film thickness of 60 nm. The substrate temperature at this time was also room temperature. Next, 1 g of magnesium was put in a resistance heating boat made of molybdenum, 500 mg of indium was put in another resistance heating boat made of molybdenum, and the vacuum chamber was depressurized to 1 × 10 ⁻⁶ Torr. Then, the resistance heating boat containing magnesium is set to 50.
Magnesium is heated to about 0 ° C to obtain 1.7 to 2.8 nm
While vaporizing at a vapor deposition rate of / s, the resistance heating boat containing indium is heated to about 800 ° C. to vaporize indium at a vapor deposition rate of 0.03 to 0.08 nm / s, so that magnesium and indium An electrode (counter electrode) made of a mixed metal and having a film thickness of 150 nm was provided on the light emitting layer.

In this way, the element structure is the anode (ITO).
Film) / hole injection layer / light emitting layer / cathode (In.Mg) organic EL device was prepared on a glass substrate, and then a copper lead wire was attached. The initial performance of this organic EL device was such that the light emission luminance was 100 cd / m ² under the conditions of a voltage of 6.5 V and a current density of 3 mA / cm ² .

(2) Preparation of moisture-proof film Example 1 Plasma C was formed on the organic EL device prepared in (1) above.
A Si—C—O moisture barrier film was formed to a thickness of 30 nm by the VD method.
The conditions for film formation are (CH ₃ ) ₃ Si—O—Si (CH ₃ ).
₃ : 20 ml / min, O ₂ : 40 ml / min, He: 150
ml / min, H ₂ : 30 ml / min, the deposition gas was controlled to 5
A high frequency power source of 0 kHz and 1 kW was used.

Example 2 On the organic EL device produced in the above (1), plasma C
A Si—N—O moisture barrier film was formed to a thickness of 30 nm by the VD method.
The conditions for film formation are (CH ₃ ) ₃ Si—O—Si (CH ₃ ).
₃ : 20 ml / min, O ₂ : 40 ml / min, N ₂ : 10 m
The film forming gas was controlled at 1 / min, He: 150 ml / min, and H ₂ : 30 ml / min, and a high-frequency power source of 50 kHz and 1 kW was used.

Example 3 A plasma C was formed on the organic EL device prepared in (1) above.
A Si—B—O moisture barrier film was formed to a thickness of 30 nm by the VD method.
The conditions for film formation are (CH ₃ ) ₃ Si—O—Si (CH ₃ ).
₃ : 20 ml / min, O ₂ : 40 ml / min, B ₂ H ₆ : 1.
0 ml / min, He: 150 ml / min, H ₂ : 30 ml /
The film-forming gas was controlled accordingly, and a high frequency power source of 50 kHz and 1 kW was used.

Comparative Example 1 No moisture-proof film was provided on the organic EL device prepared in (1) above.

Comparative Example 2 A SiO _x moisture-proof film was provided on the organic EL device manufactured in the above (1) by a vacuum deposition method to a thickness of 30 nm.

Comparative Example 3 A SiO _x moisture-proof film was formed on the organic EL device manufactured in the above (1) by a sputtering method to a thickness of 30 nm.

Comparative Example 4 Plasma C is formed on the organic EL element produced in (1) above.
A Si—C—O moisture barrier film was formed to a thickness of 30 nm by the VD method.
The conditions for film formation are (CH_Three)_ThreeSi-O-Si (CH_Three)
_Three: 20 ml / min, O_Two: 100 ml / min, He: 15
0 ml / min, H _Two: Control the film forming gas to 30 ml / min,
A high frequency power source of 50 kHz and 1 kW was used.

Comparative Example 5 Plasma C is formed on the organic EL element produced in (1) above.
A Si—C—O moisture barrier film was formed to a thickness of 30 nm by the VD method.
The conditions for film formation are (CH_Three)_ThreeSi-O-Si (CH_Three)
_Three: 100 ml / min, O_Two: 40 ml / min, He: 15
0 ml / min, H _Two: Control the film forming gas to 30 ml / min,
A high frequency power source of 50 kHz and 1 kW was used.

Organic EL of Examples 1 to 3 and Comparative Examples 1 to 5
The half-life of the device (time until the luminance drops to 0 cd / ^{m 2)} and breakdown lifetime (time until the luminance drops to 50 cd / ^{m 2)} was measured. As shown in Table 1, Example 1
It can be seen that in Comparative Examples 1 to 3, both the half life and the breaking life are longer than those of Comparative Examples 1 to 3 and there is an excellent moistureproof effect.

[0029]

[Table 1] M x y Half life (hours) Fracture life (hours) Example 1 C 0.15 1.85 1500 ≧ 10000 Example 2 N 0.12 1.88 1400 ≧ 10000 Example 3 B 0.13 1.87 1400 ≧ 10000 Comparative Example 1 − − − 20 200 Comparative Example 2 − − − 60 450 Comparative Example 3 − − − 70 500 Comparative Example 4 C 0.03 1.97 120 450 Comparative Example 5 C 0.65 1.35 80 500

Example 4 The organic EL device with Si—C—O moisture barrier film obtained in Example 1 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
After that, metal Co is used as a target and oxygen gas is 5 ×.
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Non-magnetic NaCl-type CoO was deposited to a thickness of 30 nm on the Si—C—O moisture proof film by RF magnetron sputtering method at 0 ⁻³ Torr.

Example 5 The organic EL device with Si—N—O moisture barrier film obtained in Example 2 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
After that, metal Co is used as a target and oxygen gas is 5 ×.
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Nonmagnetic NaCl-type CoO was deposited to a thickness of 0 to ³ Torr on the Si—N—O moisture-proof film by RF magnetron sputtering to a thickness of 30 nm.

Example 6 The organic EL device with Si—B—O moisture barrier film obtained in Example 3 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
After that, metal Co is used as a target and oxygen gas is 5 ×.
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Non-magnetic NaCl-type CoO was formed to a thickness of 30 nm on the Si—B—O moisture-proof film by RF magnetron sputtering at 0 ⁻³ Torr.

Example 7 The organic EL device with Si—C—O moisture barrier film obtained in Example 1 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
Then, using metallic Ni as a target and oxygen gas at 5 ×
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Non-magnetic NaCl-type NiO was deposited at a thickness of 30 nm on the Si—C—O moisture-proof film by RF magnetron sputtering method at 0 ⁻³ Torr.

Example 8 The organic EL device with Si—N—O moisture barrier film obtained in Example 2 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
Then, using metallic Ni as a target and oxygen gas at 5 ×
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Non-magnetic NaCl-type NiO was deposited on the Si—N—O moisture-proof film to a thickness of 30 nm by RF magnetron sputtering at 0 ⁻³ Torr.

Example 9 The organic EL device with Si—B—O moisture barrier film obtained in Example 3 was placed in a vacuum chamber and the pressure was reduced to 1 × 10 ⁻⁶ Torr.
Then, using metallic Ni as a target and oxygen gas at 5 ×
After introducing 10 ⁻⁴ Torr, Ar is introduced to adjust the total pressure to 5 × 1.
Non-magnetic NaCl-type NiO was deposited at a thickness of 30 nm on the Si—B—O moisture-proof film by RF magnetron sputtering at 0 ⁻³ Torr.

The measured half-life (time until the luminance drops to 50 cd / ^{m 2)} and breakdown lifetime of the organic EL device of Example 4-9 (the time until the luminance decreases to 0cd / ^{m 2).} As shown in Table 2, Examples 4 to 9 have a longer half-life than Examples 1 to 3, and when used in combination with a non-magnetic NaCl type CoO or NiO film, an excellent moistureproof effect is exhibited. I understand.

[0037]

Table 2 Half life (hours) Fracture life (hours) Example 4 2500 ≧ 10000 Example 5 2400 ≧ 10000 Example 6 2400 ≧ 10000 Example 7 2400 ≧ 10000 Example 8 2500 ≧ 10000 Example 9 2500 ≧ 10000

[0038]

As described above, according to the present invention,
SiM _x O _y (where M is at least one element selected from the group consisting of C, N and B, and is 0.05
(≦ x ≦ 0.5, 1.5 ≦ y ≦ 1.95) By covering with a film, an excellent moisture-proof effect can be obtained, and the life of the organic EL element can be extended. Also, a SiM _x O _y moisture-proof film,
When used in combination with a non-magnetic NaCl type CoO or NiO film, an even more excellent moistureproof effect can be obtained.

[Brief description of drawings]

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

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

[Explanation of symbols]

1 Organic EL device of the present invention 3 glass substrates 5 ITO electrode 7 Light-emitting layer 9 hole transport layer 11 Electron transport layer 13 Back electrode 15 power supply 17 Moisture barrier 19 additional layers

Claims (6)

[Claims] 1. An organic EL device in which an electrode, a hole transport layer, a light emitting layer, an electron transport layer and a counter electrode are laminated in this order on one main surface of a transparent substrate. At least a portion of the exposed surface is SiM
_x O _y (where M is at least one element selected from the group consisting of C, N and B, and 0.05 ≦ x ≦ 0.
5 and 1.5 ≦ y ≦ 1.95), and is covered with a moisture-proof film. 2. The film thickness of the moisture-proof film is 10 nm to 50 nm.
The organic EL element according to claim 1, wherein the organic EL element is in the range of. 3. The organic EL device according to claim 1, wherein the outer surface of the moisture-proof film is further covered with an additional thin film of optically transparent non-magnetic NaCl type CoO or NiO. . 4. The film thickness of the additional thin film is 10 nm to 50 n.
It is in the range of m, The organic EL element of Claim 3 characterized by the above-mentioned. 5. (a) A step of preparing an organic EL device in which an electrode, a hole transport layer, a light emitting layer, an electron transport layer and a counter electrode are laminated in this order on one main surface of a transparent substrate. (B) disposing the organic EL element in a chamber of a plasma CVD apparatus, and (c) at least a part of the exposed surface of the organic EL element in the chamber, SiM _x O _y (however, M Is C, N
And at least one element selected from the group consisting of B and 0.05 ≦ x ≦ 0.5, and 1.5 ≦ y ≦
1.95) is formed, and a step of forming a moisture-proof film is formed. 6. The film thickness of the moisture-proof film is 10 nm to 50 nm.
The method for producing an organic EL element according to claim 5, wherein the method is within the range.