JP2002237381A - Organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element in which directional emission is realized using a plastic lens substrate and the luminescent property is maintained for a long time. SOLUTION: A plastic lens substrate 1 having a water vapor permeability of 0.3 g/m2/24 h or less is used as an EL element substrate. A plastic lens substrate 1 having the water vapor permeability of 0.3 g/m2/24 h or less by installing a barrier layer of such as an inorganic oxide or inorganic nitride on the plastic lens substrate 1 may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device (hereinafter, referred to as an organic EL device) used for a flat light source or a display device, and a plastic substrate used for the same.

[0002]

2. Description of the Related Art Organic EL devices are expected to be applied to electronic displays and light sources as highly efficient light emitting devices. In general, a transparent material is used for a substrate, and a transparent electrode is disposed on the substrate to extract the light from the transparent substrate side because light generated inside the device needs to be extracted to the outside.

Heretofore, glass has been widely used as a transparent substrate, but there is a problem that the glass may be broken during use. Further, since the spatial light emission pattern of the emitted light is Lambertian having no directivity because the substrate is flat, the light use efficiency in the direction perpendicular to the substrate, that is, in the front direction is low. For this reason, in order to give the emitted light directivity and increase the front luminance, C.I. F. Madigan et al. (Applied Physica Letters,
vol. 76, p. 1650-1652 (2000))
A lens body made of a plastic resin is directly formed on a glass substrate as proposed in Japanese Patent Application Laid-Open No. 9-739.
It is necessary to mount a lens sheet, such as a prism sheet, on a substrate as proposed in JP-A-83.

Japanese Patent Application Laid-Open No. 9-739 discloses a method in which a plastic lens substrate is used as a substrate which is hardly damaged and has directivity to emitted light, and an organic EL element is formed directly thereon.
No. 83 is proposed. However, in the disclosed technology, a resin having a low barrier property against water vapor, such as an acrylic resin, a polycarbonate resin, and a polyethylene resin, is used for the plastic lens substrate. Can not stand. For long-term use, the water vapor permeability of the substrate is 0.3 g /
m ² / 24h or less is required.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to realize an organic EL device which can achieve directional light emission using a plastic lens substrate and can maintain light emission characteristics for a long time.

[0006]

SUMMARY OF THE INVENTION The present invention, water vapor permeability 0.3g ^/ m 2/2 by using a barrier high resin to water vapor in the material of the plastic lens substrate
4h or achieve less, to achieve the following water vapor permeability 0.3g / m 2 / ^24h by forming a water vapor barrier film such as an inorganic nitride or an inorganic oxide on a plastic lens substrate, the light emitting characteristics of the organic EL device Was found to be able to be maintained for a long time.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples, but the present invention is not limited by these examples.

FIG. 1 is a schematic view showing an embodiment of an organic EL device 10 according to the present invention. On the plastic lens substrate 1, in order, a transparent electrode 2 constituting an anode electrode, a hole transporting layer 3 having a hole transporting property, a light emitting layer 4 doped with a fluorescent dye, an electron transporting layer 5, an electron injecting layer 6, And a back electrode 7 serving as a cathode. Further, a sealing plate 8 is formed on the element.

Among these elements, a transparent electrode 2, a hole transporting layer 3 having a hole transporting property, a light emitting layer 4 doped with a fluorescent dye, an electron transporting layer 5, an electron injecting layer 6, and a back electrode 7 serving as a cathode , And the sealing plate 8 are well-known elements, and the plastic lens substrate 1 is an element proposed in the present invention. After forming a barrier layer 9 on the plastic lens substrate 1 as shown in FIG. 2, a transparent anode electrode 2, a hole transporting layer 3 having a hole transporting property, a light emitting layer 4, an electron transporting layer 5, and an electron The injection layer 6 and the back cathode electrode 7 serving as a cathode may be laminated.

[0010] The lens shape of the plastic lens substrate is
Any shape may be used as long as the emitted light can have directivity, such as a triangular prism shown in FIG. 3, a convex lens shown in FIG. 4, and an inclined shape shown in FIG. 5, and the lens shape, size, number, and arrangement are particularly limited. Not something.

Specific examples of the laminated structure of the organic EL device include anode / hole transport layer / light emitting layer / cathode, anode / hole transport layer / light emitting layer / electron injection layer / cathode, anode / light emitting layer. Layer / electron transport layer / cathode, anode / hole injection layer / emission layer / cathode, anode / hole injection layer / emission layer / electron injection layer / cathode, anode / hole injection layer / hole transport layer / emission layer / Electron transport layer / electron injection layer / cathode, etc., and the organic EL device according to the present invention may have any device configuration as long as it has at least one light emitting layer 4 between the anode 2 and the cathode electrode 6. It may be.

The hole injecting layer and the hole transporting layer are not particularly limited, but known materials used in the preparation of organic EL devices such as phthalocyanines, arylamine derivatives, and polymers containing arylamine derivatives may be appropriately used. Can be used. In addition, a conductive polymer such as polythiophenes or polyanilines can be used for the hole injection layer.

The organic compound which can be used as the light emitting layer or the electron transporting layer is not particularly limited, but includes polycyclic compounds such as p-terphenyl and derivatives thereof, anthracene,
It is possible to use condensed polycyclic hydrocarbon compounds such as naphthacene and phenanthrene and their derivatives, condensed heterocyclic compounds such as phenanthroline, bathophenanthroline and quinoxaline and their derivatives, and metal chelate complex compounds such as aluminum tris (8-quinolinolato). it can.

The light emitting layer may be a mixed film doped with different kinds of dyes. As the dopant in this case, a known organic fluorescent dye as a laser dye such as a condensed polycyclic hydrocarbon compound such as rubrene and derivatives thereof, a quinacridone derivative, and a coumarin derivative can be used.

Further, the light-emitting layer is typified by so-called π-conjugated polymers such as polyparaphenylenevinylene and derivatives thereof, polyfluorene having a fluorene unit in the main chain and copolymers thereof, and poly (N-vinylcarbazole). A non-conjugated hole transporting polymer and a sigma conjugated polymer of polysilanes can also be used.

In an organic EL device, the cathode metal electrode is oxidized or peeled off by moisture entering from the outside, and the device is deteriorated. Therefore, when a glass substrate is used, a sealing plate made of metal, glass, plastic having a water vapor barrier property, or the like is bonded from the back of the element with an epoxy resin in an inert gas such as dry nitrogen. A film having a gas barrier property such as an inorganic oxide or a nitride may be directly formed on the element instead of the sealing plate and used.

Further, when a sealing plate is used, a water catching agent such as barium oxide or calcium oxide is sealed in a portion sandwiched between the sealing plate and the substrate, and is adsorbed on the surface of the sealing plate. It is desirable to adsorb a very small amount of water molecules or water molecules that enter through a portion where the sealing plate and the substrate are bonded.

In order to manufacture a long-life element using a plastic lens substrate, it is necessary to block moisture entering through the substrate, and if a plastic having a low water vapor barrier property such as an acrylic resin and a high water absorption is used, Even when sealing is performed with a metal plate from the back surface, the element easily deteriorates due to moisture entering from the substrate side.

[0019] Therefore, to maintain the long emission characteristics must water vapor permeability of the substrate is ensured below 0.3g / m 2 / ^24h, the water vapor permeability as a resin specifically for the substrate there it is necessary to use such 0.3g ^/ m 2 ^/ 24h or less of the cycloolefin polymer resin. Further, water vapor permeability by forming a gas barrier film of an inorganic nitride or an inorganic oxide 0.3g ^/ m 2 ^/ 24h
The following may be realized.

A fluorescent compound such as an organic fluorescent dye or an inorganic fluorescent substance may be dispersed in the plastic lens substrate. In this case, the fluorescent compound dispersed in the substrate is excited by the light emitted from the element to emit light. Thereby, the emission color of the light emitted from the element can be modulated. In particular, by using a plastic lens substrate in which a yellow or orange-based fluorescent compound that is a complementary color to the blue element is dispersed, blue light is mixed with blue or yellow or orange to obtain white light having two wavelengths. I can do it.

Further, by using a plastic substrate in which both green and red fluorescent compounds are dispersed with respect to the blue element, the three primary colors of light, blue, green, and red, are mixed to produce white light having three wavelengths. Light emission can be obtained.

Embodiment 1 FIG. 1 shows the structure of an organic EL device to which the present invention is applied. Water vapor permeability using 0.23g ^/ m 2 ^/ 24h of Nippon Zeon cycloolefin polymer resin (ZEONOR)
A plastic lens substrate having a length of 40 mm, a width of 40 mm, and a thickness of 1 mm in which a triangular prism having a prism angle of 90 ° C. and a prism pitch of 50 μm was formed on one side was produced by injection molding. On the plastic lens substrate 1, a 1500 ° ITO film was formed as the anode transparent electrode 2 by a sputtering method. The following formula 1 having a hole transporting property thereon:

Embedded image Was formed at a deposition rate of 3 ° / sec and a thickness of 400 ° at 10 ⁻⁶ torr to form a hole transport layer 3.

Next, on the hole transporting layer 3, an electron transporting light emitting layer 4 represented by the following formula 2:

Embedded image A tris (8-quinolinolato) aluminum complex (hereinafter, referred to as “Alq”) represented by the following formula:

Embedded image Was formed by co-evaporation from separate evaporation sources under a vacuum of 10 ⁻⁶ Torr to form 200 °.

Next, Alq was added to the electron transport layer 5 by 10 ^−6.
Formed under a vacuum of Torr at 300 °. Finally, 5 ° lithium fluoride was deposited as the electron injection layer 6 and 1000 ° aluminum was deposited at the same vacuum as the back electrode 7 serving as a cathode. The element emission area was 5 mm × 5 mm. Finally, an epoxy resin was applied to the outer peripheral portion of the element, and a stainless steel plate having a thickness of 0.1 mm was attached and sealed.

When a DC voltage is applied between ITO2 as the anode electrode and aluminum 7 as the cathode electrode, yellow light emission having a peak at 560 nm derived from rubrene in the light emitting layer 4 is observed through the substrate, and at 8 V, 45500 c
It exhibited a high luminance of d / m ² . The device was allowed to stand at room temperature and the storage durability was examined. As a result, even after one month, the light emission characteristics were hardly reduced.

COMPARATIVE EXAMPLE 1 Using a normal flat substrate having a thickness of 1 mm and having no prism body made of Zeonor resin manufactured by Zeon Corporation, a film was formed from the anode transparent electrode 2 to aluminum 7 under the same conditions as in Experimental Example 1. did. Finally, an epoxy resin is applied to the outer periphery of the element, and a stainless steel plate having a thickness of 0.1 mm is stuck in dry nitrogen.
Sealing was performed.

When a DC voltage was applied between ITO2 as the anode electrode and aluminum 7 as the cathode electrode, yellow light emission peaking at 560 nm derived from rubrene in the light emitting layer 4 was observed through the glass substrate. At 2
9800 cd / m ² , showing only about 65% of the luminance of Experimental Example 1. The device was allowed to stand at room temperature and the storage durability was examined. As a result, even after one month, the light emission characteristics were hardly reduced.

Comparative Example 2 A flat substrate was produced by injection molding in the same manner as in Comparative Example 1 using an acrylic resin manufactured by Sumitomo Chemical Co., and aluminum 7 was formed from the anode transparent electrode 2 under the same conditions as in Experimental Example 1. Finally, an epoxy resin was applied to the outer periphery of the element, and a stainless steel plate having a thickness of 0.1 mm was stuck in dry nitrogen to perform sealing.

When a DC voltage was applied between ITO 2 as the anode electrode and aluminum 7 as the cathode electrode, yellow light emission peaking at 560 nm derived from rubrene in the light emitting layer 4 was observed through the substrate. 3150
0 cd / m ² , about 69% of Experimental Example 1, and only luminance equivalent to Comparative Example 1 were shown. The device was left standing at room temperature and the storage durability was examined. After one month, the brightness decreased to 5% of the initial value, and the non-light-emitting portion called a dark spot occupied about 95% of the device, and the device was significantly deteriorated. Was.

Embodiment 2 FIG. 2 shows the structure of an organic EL device to which the present invention is applied. Using a Sumitomo Chemical acrylic resin, prism angle 9 on one side
A plastic lens substrate having a length of 40 mm, a width of 40 mm, and a thickness of 1 mm on which a triangular prism having a prism pitch of 50 μm was formed at 0 ° C. was produced by an injection molding method. A silicon nitride film having a thickness of 1 μm was formed on the plastic lens substrate 1 by a sputtering method. Under the same conditions as in Experimental Example 1,
Films from the anode transparent electrode 2 to the cathode aluminum 7 were formed. Finally, an epoxy resin was applied to the outer periphery of the element, and a stainless steel plate having a thickness of 0.1 mm was stuck in dry nitrogen to perform sealing.

When a DC voltage is applied between ITO2 as the anode electrode and aluminum 7 as the cathode electrode, yellow light emission having a peak at 560 nm derived from rubrene in the light emitting layer 4 is observed through the substrate.
It exhibited a high luminance of d / m ² . The device was allowed to stand at room temperature and the storage durability was examined. As a result, even after one month, the light emission characteristics were hardly reduced.

Example 3 Using a cycloolefin polymer resin (Zeonor) manufactured by Zeon Corporation in which 1% by weight of an orange fluorescent dye DCM1 represented by the following formula 4 was dispersed, a prism angle of 90 ° C. was applied to one surface.
A plastic lens substrate having a length of 40 mm × width of 40 mm and a thickness of 1 mm on which a triangular prism having a prism pitch of 50 μm was formed was produced by an injection molding method. On the plastic lens substrate 1, a 1500 ° ITO film was formed as the anode transparent electrode 2 by a sputtering method. An NPD having a hole transporting property was formed thereon to a thickness of 400 ° at a deposition rate of 3 ° / sec under 10 ⁻⁶ torr to form a hole transporting layer 3.

Next, on the hole transport layer 3, an electron transporting light emitting layer 4 represented by the following formula 5:

Embedded image A bis (2-methyl-8-quinolinolato) mono (4-phenylphenolate) aluminum complex (hereinafter referred to as "BAlq") represented by the following formula 6 so as to be 1% by weight:

Embedded image Was formed by co-evaporation from separate evaporation sources under a vacuum of 10 ⁻⁶ Torr to form 200 °.

Next, Alq is used as the electron transport layer 5 by 10 ^−6.
Formed under a vacuum of Torr at 300 °. Finally, 5 ° lithium fluoride was deposited as the electron injection layer 6 and 1000 ° aluminum was deposited at the same vacuum as the back electrode 7 serving as a cathode. The element emission area was 5 mm × 5 mm. Finally, an epoxy resin was applied to the outer periphery of the element, and a stainless steel plate having a thickness of 0.1 mm was stuck in dry nitrogen to perform sealing.

When a DC voltage is applied between ITO2 as an anode electrode and aluminum 7 as a cathode electrode, blue light emission having two peaks at 450 nm and 470 nm derived from perylene of the light emitting layer 4 and 570 nm derived from DCM1 are generated. White light emission in which orange light emission having a peak is mixed is observed through the substrate, and at 8 V, 5200 cd / m ²
High brightness. The device was allowed to stand at room temperature and the storage durability was examined. As a result, even after one month, the light emission characteristics were hardly reduced.

[0036]

As described above, the organic EL element of the present invention has high gas barrier properties and uses a plastic lens substrate having low water vapor permeability. The front brightness was increased, and long-term use was realized. Therefore, the organic EL device of the present invention has extremely high practicality, and can be expected to be effectively used as a light source or a liquid crystal backlight.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an organic EL device applied in Example 1.

FIG. 2 is a cross-sectional view of an organic EL element applied in Example 2.

FIG. 3 shows a plastic lens substrate having a triangular prism.

FIG. 4 shows a plastic lens substrate having a convex lens.

FIG. 5 is a plastic lens substrate in which one side of the substrate is inclined.

[Explanation of symbols]

 Reference Signs List 1 plastic lens substrate 2 transparent anode electrode 3 hole transport layer 4 light emitting layer 5 electron transport layer 6 electron injection layer 7 back cathode electrode 8 sealing plate 9 barrier layer 10 organic EL element

Claims (5)

[Claims] 1. A plastic lens substrate for the following organic electroluminescence element water vapor permeability is 0.3g ^/ m 2 ^/ 24h Wherein the inorganic oxide or inorganic nitride such as a plastic lens substrate for an organic electroluminescence device barrier layer provided water vapor permeability is less 0.3 g / m 2 / ^24h of 3. A plastic lens substrate for an organic electroluminescence device, wherein a fluorescent compound is mixed in the plastic substrate according to claim 1. 4. An organic electroluminescence device using the plastic lens substrate according to claim 1. 5. An organic electroluminescent device using the plastic lens substrate according to claim 3 and emitting white light.