WO2014084210A1

WO2014084210A1 - Light emission device

Info

Publication number: WO2014084210A1
Application number: PCT/JP2013/081782
Authority: WO
Inventors: 祐介山▲崎▼
Original assignee: 昭和電工株式会社
Priority date: 2012-11-28
Filing date: 2013-11-26
Publication date: 2014-06-05

Abstract

A light emission device having a light emission region comprising a plurality of minute light emission units electrically connected in parallel, the light emission device including, in the light emission region, a planar conductor, an insulation layer formed on the upper surface of the planar conductor, a plurality of openings formed in the insulation layer, a plurality of first electrodes formed on the insulation layer, an organic compound layer including a light emission layer, the organic compound layer being formed so as to cover the plurality of first electrodes, and a second electrode formed on the organic compound layer, and comprises a plurality of sections each containing at least two of the first electrodes. At least some of the plurality of first electrodes are formed also in the openings and are electrically connected to the conductor, and thereby form electrodes that conduct, in the plurality of minute light emission units, with the organic compound layer. Each of the plurality of openings has a thin shape having a first major axis and a first minor axis orthogonal to each other in plan view, and the openings are formed so that in each section, the first major axes are parallel to each other. Each of the plurality of first electrodes has a thin shape having a second major axis and a second minor axis orthogonal to each other in plan view, and the first electrodes are formed so that in each section, the second major axes are parallel to each other. In each of the plurality of sections, the distance between the openings in the direction of the first minor axes of the openings is less than the length of the second major axes of the first electrodes and greater than the length of the second minor axes of the first electrodes. Each of the plurality of sections includes at least two sections between which the angle between the first major axes of the openings and the second major axes of the first electrodes in each of the sections is different.

Description

Light emitting device

The present invention relates to a light emitting device using an organic light emitting element that emits light by applying a voltage to an organic compound layer including a light emitting layer sandwiched between a pair of electrodes.

Organic light-emitting elements using organic compounds as light emitters are expected to be applied to lighting applications in recent years because of their high luminous efficiency and long lifetime, and research on increasing the area has been actively conducted. A planar light-emitting body used as illumination is obtained by forming an organic compound layer with a uniform thickness on a planar electrode having a smooth surface and covering it with a counter electrode.

Patent Document 1 discloses an organic light-emitting element in which an insulating layer is provided on an electrode, a non-light-emitting region is formed in a light-emitting surface, and the luminance is controlled by controlling the density of the non-light-emitting region.
On the other hand, in Patent Document 2, a dielectric layer is disposed between a hole injection electrode layer and an electron injection electrode layer, and an electroluminescent layer is formed inside a cavity formed so as to penetrate the dielectric layer. Arranged light emitting elements are disclosed.

JP2007-294441 Special table 2010-509729

By the way, in the planar light emitting body, as the area of the light emitting surface is increased, the luminance unevenness due to the internal resistance of the electrode is reduced, and conversely, the luminance of a desired region is made higher than the surroundings. Therefore, it is necessary to easily control the luminance distribution in the light emitting surface.
However, for example, in the case of the technique disclosed in Patent Document 1, it is not easy to form such a complicated insulating layer pattern on the entire surface, particularly in the case of a large-area planar light emitter.
In addition, the light emitting device described in Patent Document 2 also includes a pseudo surface light emitter that looks like a surface light emitter by arranging a plurality of fine holes (cavities) that are light emitting portions on the hole injection electrode layer. can do. However, in this case, since the electrodes are common to the plurality of light emitting units, it is not easy to control the luminance.

Here, when trying to adopt a method of adjusting the luminance unevenness by changing the formation density of the cavity,
(1) Designing a cavity having an appropriate distribution of distribution density and arrangement to cancel the luminance distribution,
(2) An element having the designed cavity structure is manufactured.
Therefore, it is necessary to prepare a mask or the like every time the cavity is formed.

An object of the present invention is to provide a light-emitting device using an organic light-emitting element that can easily control the luminance distribution in the light-emitting surface of the organic light-emitting element and can be easily produced. More specifically, the present invention provides an organic EL device using an organic EL element that does not require reworking of a mask necessary for the above-described conventional technique in order to eliminate luminance unevenness of the organic EL element having a cavity structure. .

The present inventor has disclosed a luminance gradient in a light emitting surface by changing an angle formed by a major axis of the shape of an opening and an electrode in a light emitting device including a plurality of minute light emitting units including an elongated opening and an electrode. The present invention was completed by finding a light-emitting device using an organic light-emitting element that can be easily controlled.

That is, according to the present invention, a light-emitting device having a light-emitting region composed of a plurality of minute light-emitting portions electrically connected in parallel, wherein the light-emitting device has one planar conductor in the light-emitting region. An insulating layer formed on an upper surface of the planar conductor, a plurality of openings formed in the insulating layer, a plurality of first electrodes formed on the insulating layer, and the plurality of first electrodes An organic compound layer including a light-emitting layer formed over one electrode; and a second electrode formed on the organic compound layer; and a plurality of sections each including two or more first electrodes. And at least a part of the plurality of first electrodes is also formed in the opening and is electrically connected to the conductor so that the organic compound layer is energized in the plurality of minute light emitting portions. The plurality of openings are in plan view. The first major axis and the first minor axis orthogonal to each other have an elongated shape, and the first major axis is formed in parallel with each other in one of the sections, and the plurality of the first major axes are formed. The electrode has an elongated shape having a second major axis and a second minor axis orthogonal to each other in a plan view, and is formed so that the second major axis is parallel to each other in one of the compartments. In each of the plurality of sections, a distance between the openings in the direction of the first short axis of the opening is shorter than a length of the second long axis of the first electrode, and the first The plurality of sections are longer than the length of the second short axis of one electrode, and the first long axis of the opening and the second long axis of the first electrode are in each of the plurality of sections. The angle formed includes at least two sections that are different from each other among the plurality of sections. Emitting device is provided to symptoms.

It is preferable that the first electrode electrically connected to the conductor and the first electrode not electrically connected to the conductor are mixed in the light emitting region.
One of the first long axis of the opening and the second long axis of the first electrode is preferably parallel to each other in the light emitting region.
The lengths of the first major axis of the opening and the second major axis of the first electrode are respectively the first minor axis of the opening and the second minor axis of the first electrode. The length is preferably 5 times or more.
In the light emitting region, it is preferable that the shapes and sizes of the plurality of openings are the same and / or the shapes and sizes of the plurality of first electrodes are all the same.
The arrangement pattern of the plurality of openings and the arrangement pattern of the plurality of first electrodes are the same for each of the plurality of sections, and only the angle formed by the first major axis and the second major axis is different. Is preferred.

The length of the first short axis and the length of the second short axis of the opening are preferably 0.1 μm to 10 μm, respectively. Further, the opening portion and the first electrode, which is preferably respectively 10 ² to 10 ⁸ formed in any 1mm square area of the light emitting region.
It is preferable that any one of the plurality of openings and the plurality of first electrodes is formed so that the long axes face each other in parallel and periodically in the light emitting region.
The planar conductor is a transparent conductive film made of a metal oxide, and is electrically connected to at least a part of the outer side of the light emitting region with the planar conductor and connected to a power source. And the angle formed by the first long axis of the opening and the second long axis of the first electrode is such that the area ratio of the light emitting portion in the section is far from the terminal portion. It is preferable that the section is set to be larger.
It is preferable that the angle is larger as the section is farther from the terminal portion.

According to the present invention, a luminance distribution gradient in the light emitting surface of an organic light emitting element is easily controlled, and a light emitting device using such an organic light emitting element is provided.

It is a fragmentary sectional view of the light emission part vicinity of the light-emitting device to which this Embodiment is applied. It is a figure explaining an example of the shape and relative arrangement | positioning of an opening part and a 1st electrode in the light-emitting device to which this Embodiment is applied. It is a figure explaining an example in which the direction of a 1st electrode changes with the distance from a terminal part in the light emission area | region in the light-emitting device to which this Embodiment is applied. It is a figure explaining the example of the planar shape of a 1st electrode and an opening part.

Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. That is, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. . The drawings used are examples for explaining the present embodiment and do not represent actual sizes. The size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in this specification, “on” such as “on the layer” is not necessarily limited to the case where it is formed in contact with the upper surface, and is formed on the upper side in a separated manner or between layers. It is used in a sense that includes an intervening layer.

(Light emitting device)
The light-emitting device to which this embodiment is applied has a plurality of light-emitting portions that are electrically connected in parallel and have a minimum width of 0.1 μm to 10 μm, and a light-emitting region that includes all of these light-emitting portions. Have. The light emitting device may have only one light emitting region or two or more light emitting regions. The light emitting device has one planar conductor in each light emitting region. In each light emitting region, the light emitting device to which this embodiment is applied is further formed on the upper surface of a planar conductor, and has an insulating layer having a plurality of openings and a plurality of insulating layers formed on the insulating layer. A first electrode; an organic compound layer including a light emitting layer formed to cover the plurality of first electrodes; and a second electrode formed on the organic compound layer. Each light emitting area is divided into a plurality of sections, and each section includes two or more of the first electrodes. The plurality of sections may be the same or different in area and shape.

(Light Emitting Unit 10)
FIG. 1 is a partial cross-sectional view in the vicinity of a light emitting unit 10 of a light emitting device to which the present embodiment is applied. As shown in FIG. 1, a light emitting unit 10 of a light emitting device includes a planar conductor 12, an insulating layer 13, a first electrode 14, an organic compound layer 15 including a light emitting layer, and a second electrode 16 stacked on a substrate 11. Has been. An opening 17 is provided in the insulating layer 13, and the first electrode 14 is electrically connected to the conductor 12 at a part inside the opening 17. When the first electrode 14 and the conductor 12 are electrically connected inside the opening 17, and a voltage is applied between the first electrode 14 and the second electrode 16, the first of the organic compound layer 15. The portion in contact with the electrode 14 emits light. Note that the first electrode 14 may be electrically connected to the conductor 12 throughout the opening 17.

(Substrate 11)
The substrate 11 serves as a support for forming the conductor 12, the insulating layer 13, the first electrode 14, the organic compound layer 15, and the second electrode 16. A material that satisfies the mechanical strength required for the light emitting device including the light emitting unit 10 is used for the substrate 11.
As a material used for the substrate 11, when it is desired to extract light emitted from the light emitting layer from the substrate 11 side, it is necessary to have transparency to this light. Specifically, glass such as sapphire glass, soda glass, and quartz glass; transparent resin such as polymethyl methacrylate resin, polycarbonate resin, polyester resin, and silicone resin; transparent metal nitride such as aluminum nitride; transparent metal such as alumina An oxide etc. are mentioned. In addition, when using the resin film which consists of the said transparent resin as the board | substrate 11, it is preferable that gas permeability with respect to gas, such as water and oxygen, is low, and in the range which does not impair light permeability largely, it is a transparent resin film. It is preferable to form a gas barrier thin film that suppresses gas permeation.

When it is not necessary to extract light emitted from the light emitting layer from the substrate 11 side, the material of the substrate 11 is not limited to the transparent material described above, and an opaque material can also be used. Specifically, such materials include silicon (Si), copper (Cu), silver (Ag), gold (Au), platinum (Pt), tungsten (W), titanium (Ti), tantalum (Ta), Alternatively, niobium (Nb), aluminum (Al) alone, alloys containing these, stainless steel, and other substrate materials that are usually used in top emission type organic EL elements. In the case where the conductor 12 is transparent, the opaque substrate 11 is made of a highly light-reflective metal material or the above-described light transmittance in order to extract more light emitted from the light emitting layer to the outside. You may use what formed the light reflection film which consists of a light reflective metal material in the surface of the material which has. In addition, in order to release heat generated by light emission of the element light emitting unit 10, it is preferable to use a material having high thermal conductivity for the substrate.
The thickness of the substrate 11 is appropriately selected depending on the required mechanical strength and is not particularly limited. However, in the present embodiment, it is preferably 0.1 mm to 10 mm, more preferably 0.25 mm to 2 mm.

(Conductor 12)
The conductor 12 is formed in a planar shape continuous over the entire light emitting region on the substrate 11 and supplies power to the first electrode 14 in the light emitting region. The material used for the conductor 12 is not particularly limited as long as it has electrical conductivity. When it is desired to extract light emitted from the light emitting layer from the substrate 11 side, the material forming the conductor 12 needs to be transmissive to this light. As such a material, a metal oxide is preferable. Specifically, for example, indium tin oxide (ITO), indium zinc oxide (IZO), transparent inorganic oxides such as tin oxide, conductive polymers such as polyaniline, and conductive polymers doped with any acceptor, Examples thereof include conductive light transmissive materials such as carbon nanotubes, thin film metals, metal nanowires formed in a thin film shape, and composite materials containing these. The thickness of the conductor 12 can be formed in the range of 2 nm to 2 μm, for example. However, 50 nm or more is preferable from the viewpoint of high conductivity, and 500 nm or less is preferable in that high light transmittance is maintained.

When it is not necessary to take out the light emitted from the light emitting layer from the substrate 11 side, as the material of the conductor 12, the metal materials mentioned as the opaque material that can be used for the substrate 11 can be used. Further, the conductor 12 can also serve as the substrate 11. Accordingly, the thickness of the conductor 12 made of a metal material is preferably 2 nm to 10 mm, and more preferably 50 nm to 2 mm.

(Insulating layer 13)
The insulating layer 13 is laminated on the conductor 12 and separates and insulates the conductor 12 and the first electrode 14 at locations other than the opening 17. For this reason, the insulating layer 13 is preferably a material having a high resistivity. Specifically, the resistivity is preferably 10 ⁸ Ω · cm or more, and more preferably 10 ¹² Ω · cm or more. Specific examples of the material for the insulating layer 13 include metal nitrides such as silicon nitride, boron nitride, and aluminum nitride; and metal oxides such as silicon oxide and aluminum oxide. Furthermore, polymer compounds such as polyimide, polyvinylidene fluoride, and parylene, spin-on glass (SOG), and the like can also be used.

The thickness of the insulating layer 13 is preferably not more than 5 μm so that the electric resistance between the conductor 12 and the first electrode 14 does not become too large. However, if it is too thin, the dielectric strength may not be sufficient. Accordingly, it is preferable to form the film with a thickness of 10 nm to 5 μm, more preferably 50 nm to 500 nm.

In addition, when the insulating layer 13 extracts light from the surface on the substrate 11 side, the light extracted from the substrate 11 can be increased by refracting light incident from the organic compound layer 15 and changing the traveling direction of the light. it can. For this purpose, as the material of the insulating layer 13, a material having a high transmittance for emitted light and having a higher refractive index or a lower refractive index than the organic compound layer is used. The absolute value of the difference from the refractive index is preferably larger than 0.1.

(Opening 17)
The opening 17 is formed through the insulating layer 13. In addition, at least a part of the plurality of first electrodes 14 formed on the insulating layer 13 is electrically connected to the conductor 12 inside the opening 17, whereby the first electrode 14 is formed from the conductor 12. Is supplied with power.
The opening 17 may be formed so as to penetrate through the conductor 12, and in this case, the bottom of the opening 17 is the top surface of the substrate 11, and the first electrode 14 is connected to the side surface of the conductor 12 inside the opening 17. Electrically connected. When a voltage is applied between the first electrode 14 and the second electrode 16, a current flows between the electrodes, and the light emitter included in the light emitting layer of the organic compound layer 15 emits light. Therefore, at this time, the region on the first electrode 14 in a plan view is a light emitting portion.

(First electrode 14)
In the present embodiment, a plurality of first electrodes 14 exist in one light emitting region. The first electrode 14 is an electrode in which at least a part of the first electrode 14 is also formed in the opening 17 and is electrically connected to the conductor 12, thereby energizing the organic compound layer 15 in a plurality of light emitting portions. Function as. In the present embodiment, the first electrode 14 is an anode. The first electrode 14 is electrically connected to the conductor 12 inside the opening 17, and injects holes into the organic compound layer 15 by applying a voltage between the second electrode 16.

The material used for the first electrode 14 is preferably a material having high electrical conductivity and a work function of 4.5 eV or more. When it is desired to extract light emitted from the light emitting layer from the substrate 11 side, examples of such a material include conductive metal oxides such as ITO, IZO, and tin oxide, metals, and the like. Moreover, you may use the electroconductive material which consists of organic substances, such as a polyaniline derivative, a polythiophene derivative, and the mixture of these polymers, and a polystyrene sulfonic acid. Of these, ITO, IZO and poly (3,4-ethylenedioxythiophene) -polystyrene sulfonic acid mixture (PEDOT: PSS), which easily inject holes into the organic compound layer 15, are preferable.
When it is not necessary to extract light emitted from the light emitting layer from the substrate 11 side, those listed as opaque materials that can be used for the conductor 12 can be used.

As described above, in order to improve the light extraction efficiency, when the emitted light is incident on the side surface of the opening 17 of the insulating layer 13 and the light is extracted, the first electrode 14 transmits the emitted light. It is necessary to use materials with a high rate. In this respect, among the above materials, a conductive material made of a conductive metal oxide or an organic material is preferable.

The first electrode 14 can be formed with a thickness of 2 nm to 2 μm, for example. However, 50 nm or more is preferable from the viewpoint of high conductivity, and 500 nm or less is preferable from the viewpoint of easy patterning of the first electrode 14 and formation of the organic compound layer 15. The work function can be measured by a method such as ultraviolet photoelectron spectroscopy.
The end of the first electrode 14 is preferably provided with measures for preventing a short circuit between the first electrode 14 and the second electrode 16. Specifically, the end of the first electrode 14 is tapered in an elevational view (the surface on the insulating layer 13 side is larger than the surface on the organic layer compound layer 15 side), or the first electrode in a plan view. It is preferable to form an insulating protective layer on the first electrode 14 so as to overlap with the first electrode 14.

(Organic compound layer 15)
The organic compound layer 15 includes a light emitting layer, and includes a single layer or a layer including a plurality of stacked organic compounds. In the present embodiment, the organic compound layer 15 covers the first electrode 14 and is formed as a continuous film on the entire surface of the light emitting region. Is done. The light emitting layer includes a light emitting material that emits light when a voltage is applied between the first electrode 14 and the second electrode 16. As such a light emitting material, a known light emitting material can be used, and any of a light emitting polymer compound and a light emitting non-polymer compound can be used. In this embodiment mode, a phosphorescent organic compound or an organometallic complex is preferably used as the light-emitting material. In the present embodiment, as shown in FIG. 1, the organic compound layer 15 is formed as a continuous film over the entire surface of the light emitting region so as to cover the first electrode 14, but the organic compound layer 15 is formed on the first electrode 14. The organic compound layer 15 may not be formed on the insulating layer 13 as long as it is formed.

Furthermore, in the present embodiment, it is very desirable to use a cyclometalated complex as the light emitting material from the viewpoint of improving the light emission efficiency. Examples of cyclometalated complexes include 2-phenylpyridine derivatives, 7,8-benzoquinoline derivatives, 2- (2-thienyl) pyridine derivatives, 2- (1-naphthyl) pyridine derivatives, 2-phenylquinoline derivatives, and the like. Examples of the complex include iridium (Ir) having a ligand; platinum (Pt) and gold (Au). Among these, an Ir complex is particularly preferable. The cyclometalated complex may have other ligands in addition to the ligands necessary for forming the cyclometalated complex. The cyclometalated complex includes a compound that emits light from triplet excitons, and such a compound is preferable from the viewpoint of improving luminous efficiency.

Examples of the light emitting polymer compound include poly-p-phenylene vinylene (PPV) derivatives such as (poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene]) (MEH-PPV). Π-conjugated polymer compounds such as polyfluorene derivatives and polythiophene derivatives; non-conjugated polymers in which a dye molecule and a tetraphenyldiamine derivative or a triphenylamine derivative are introduced into the main chain or side chain. A light emitting polymer compound and a light emitting non-polymer compound may be used in combination.

The light emitting layer may contain a host material together with the light emitting material, and the light emitting material may be dispersed in the host material. Such a host material preferably has a charge transporting property, and is preferably a hole transporting compound or an electron transporting compound.

The organic compound layer 15 may include a hole transport layer (not shown) for receiving holes from the first electrode 14 and transporting them to the light emitting layer. The hole transport layer is provided between the first electrode 14 and the light emitting layer.
As a hole transport material for forming such a hole transport layer, a known material can be used. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) -1,1′-biphenyl-4,4′diamine (TPD), 4,4′-bis [N- (1- Naphthyl) -N-phenylamino] biphenyl (α-NPD), 4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA), and the like; polyvinylcarbazole A polymer compound obtained by polymerizing the above triphenylamine derivative by introducing a polymerizable substituent. The above hole transport materials may be used singly or in combination of two or more, and a plurality of hole transport layers formed from different hole transport materials may be laminated.

Further, a hole injection layer (not shown) for relaxing the hole injection barrier may be provided between the hole transport layer and the first electrode 14. Examples of the material for forming the hole injection layer include known materials such as copper phthalocyanine, fluorocarbon, and silicon dioxide. Further, a mixture of a hole transport material used for the hole transport layer and an electron acceptor such as 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinonedimethane (F4TCNQ) may be used. it can. When the 1st electrode 14 is formed from materials other than conductive polymers, such as ITO and IZO, in addition to said material, conductive polymers, such as PEDOT: PSS, can also be used as a hole injection layer.

The organic compound layer 15 includes an electron transport layer (not shown) for receiving electrons from the second electrode 16 serving as a cathode and transporting the electrons to the light emitting layer, between the light emitting layer and the second electrode 16. Also good. Examples of materials that can be used for such an electron transport layer include aluminum complexes, zinc complexes, quinoline derivatives, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, and triarylborane derivatives. And triphenylphosphine oxide derivatives. More specifically, tris (8-quinolinolato) aluminum (abbreviation: Alq), bis [2- (2-hydroxyphenyl) benzoxazolate] zinc, bis [2- (2-hydroxyphenyl) benzothiazolate] zinc 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole and the like.

In addition, for the purpose of suppressing the passage of holes through the light emitting layer between the electron transport layer and the light emitting layer and efficiently recombining holes and electrons in the light emitting layer, a hole blocking layer ( (Not shown) may be provided. This hole blocking layer can also be regarded as one of the layers included in the organic compound layer 15. In order to form the hole blocking layer, a known material such as a triazole derivative, an oxadiazole derivative, or a phenanthroline derivative can be used.

The thickness of each of the layers constituting the organic compound layer 15 is appropriately selected in consideration of charge mobility, charge injection balance, interference of emitted light, and the like, and is not particularly limited. In this embodiment mode, the thickness is preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm, and particularly preferably 5 nm to 200 nm. Further, the total thickness of the organic compound layer 15 between the first electrode 14 and the second electrode 16 is preferably 30 nm to 1 μm, more preferably 50 nm to 500 nm.
Note that by controlling the thickness of the organic compound layer 15, a microresonator structure can be formed, and the spectrum and intensity of light extracted outside the light emitting device can be changed. In this case, one of the first electrode 14 and the second electrode 16 is a semi-reflective electrode (not shown) made of a metal thin film having a thickness of 5 nm to 50 nm, and the other electrode is a reflective electrode. An electrode (not shown) is used.

(Second electrode 16)
The second electrode 16 injects electrons into the organic compound layer 15 when a voltage is applied between the second electrode 16 and the first electrode 14. That is, in the present embodiment, the second electrode 16 is a cathode. The second electrode 16 is formed as a continuous film on the entire surface of the light emitting region on the organic compound layer 15. The material used for the second electrode 16 is not particularly limited as long as it has electrical conductivity. In the present embodiment, a material having a low work function and being chemically stable is preferable. Specifically, aluminum (Al), magnesium-silver (MgAg) alloy, Al-Ag such as aluminum-lithium (AlLi) and aluminum-calcium (AlCa), and an alloy of alkaline earth metal (or alkali metal), etc. Materials. However, the material of the second electrode 16 is preferably a material transparent to visible light, for example, similar to the first electrode 14 when it is desired to extract light emitted from the light emitting layer from the second electrode 16 side.
The thickness of the second electrode 16 is preferably 10 nm to 1 μm, and more preferably 50 nm to 500 nm. If the thickness of the second electrode 16 is less than 10 nm, the sheet resistance increases, and the driving voltage of the light emitting unit 10 tends to increase. Easy to accumulate.

Further, a cathode buffer layer (not shown) is provided adjacent to the second electrode 16 for the purpose of lowering the electron injection barrier from the second electrode 16 to the organic compound layer 15 and increasing the electron injection efficiency. It may be provided on the 15 side. Examples of the cathode buffer layer include alkali metals (Na, K, Rb, Cs), magnesium (Mg), alkaline earth metals (Sr, Ba, Ca), rare earth metals (Pr, Sm, Eu, Yb), or A material selected from fluorides, chlorides and oxides of these metals or a mixture of two or more thereof can be used. The thickness of the cathode buffer layer is preferably from 0.1 nm to 50 nm, more preferably from 0.1 nm to 20 nm, and even more preferably from 0.5 nm to 10 nm.

In the present embodiment, in the light emitting unit 10 of the light emitting device shown in FIG. 1, the first electrode 14 formed in contact with the conductor 12 is an anode, and the second electrode 16 formed on the organic compound layer 15 is Although it is a cathode, an anode and a cathode may be reversed. That is, the first electrode 14 may be a cathode and the second electrode 16 may be an anode.
When the first electrode 14 and the second electrode 16 have such a configuration, an electron injection layer, an electron transport layer, and a hole blocking layer may be provided in the organic compound layer 15 between the first electrode 14 and the light emitting layer. it can. In addition, a hole injection layer, a hole transport layer, and an electron blocking layer can be provided in the organic compound layer 15 between the second electrode 16 and the light emitting layer.

In order to form the conductor 12, the insulating layer 13, the first electrode 14, the organic compound layer 15 and the second electrode 16 formed on the substrate, resistance heating vapor deposition, electron beam vapor deposition, sputtering, ion A plating method, a CVD method, or the like can be used.
In addition, when a coating film forming method (that is, a method in which a target material is dissolved in a solvent and applied to the substrate 11 and drying) is possible, a spin coating method, a dip coating method, an ink jet method, a printing method, It is also possible to form a film using a method such as a spray method or a dispenser method. Among these, it is preferable to use the resistance heating vapor deposition method and the coating film forming method for forming the organic compound layer 15.

(Relative arrangement of opening and first electrode)
FIG. 2 is a diagram illustrating an example of the shape of the opening 17 and the first electrode 14 and their relative arrangement in the light emitting device to which the present embodiment is applied.
FIG. 2 shows the shape and relative arrangement of the plurality of openings 17 and the plurality of first electrodes 14 in a plan view in one section in the light emitting region of the light emitting device to which the present embodiment is applied. .

FIG. 2A shows a plurality of openings 17 having a rectangular planar shape, and a plurality of rectangular first electrodes 14 having a rectangular shape in the same light emitting region. The example arrange | positioned so that it may cross substantially orthogonally is shown.
As shown in FIG. 2A, each of the plurality of openings 17 has an elongated rectangular shape having a first major axis and a first minor axis that are orthogonal to each other, and the first major axis faces each other. Are arranged in parallel, and are arranged periodically at regular intervals in the vertical and horizontal directions. Here, the first long axis of the opening 17 indicates the long side of the rectangle, and the first short axis indicates the short side of the rectangle.

In the present embodiment, it is preferable that the length of the first major axis of the opening 17 is three times or more the length of the first minor axis. Further, it is more preferably 5 times or more the length of the first short axis.
Note that the lengths of the first major axis and the first minor axis in the elongated shape are not strictly defined for every shape, but are, for example, the maximum width of the shape in each axial direction. Is defined.
Further, the most preferable case of the opening 17 is when the length of the long axis = the length of the light emitting surface. That is, one opening 17 is not divided in the major axis direction. If the area of the opening 17 is large, the contact area between the light emitting layer and the first electrode 14 increases, and the light emitting area increases.

Further, as shown in FIG. 2A, each of the plurality of first electrodes 14 has an elongated rectangular shape having a second major axis and a second minor axis that are orthogonal to each other, and each has a certain length and width. It is formed at intervals. Here, the second long axis of the first electrode 14 indicates the long side of the rectangle, and the second short axis indicates the short side of the rectangle.

In the present embodiment, the planar shapes of the plurality of first electrodes 14 are substantially the same. A plurality of first electrodes 14 are preferably included in one section. In this case, the plurality of first electrodes 14 are formed so that the second major axes are parallel to each other.
In FIG. 2A, the positions of the plurality of first electrodes 14 are periodically arranged. However, the present embodiment is not limited to this, and the first electrodes 14 may be arranged randomly within the above range. good. However, when one section is viewed macroscopically, the plurality of first electrodes 14 need to be distributed with a substantially uniform density. The plurality of first electrodes 14 are preferably arranged so that the ratio of the area where the electrodes are formed to the area of the light emitting region is increased. Specifically, it is preferable that the area occupation ratio of the first electrode 14 in the light emitting region is 50% or more, and by setting it in such a range, it is possible to keep the macroscopic luminance of the light emitting region high. .

As described with reference to FIG. 1, when the first electrode 14 and the conductor 12 are electrically connected inside the opening 17 to apply a voltage to the first electrode 14 and the second electrode 16, the organic compound layer The portion in contact with the first electrode 14 emits light.

Here, in FIG. 2A, the angle (θ) formed between the direction of the first major axis in the plurality of openings 17 and the direction of the second major axis in the plurality of first electrodes 14 is 90 degrees. It is arranged to be. In the present specification, the angle formed by the first major axis and the second major axis is represented by the angle on the acute side of the angles at which the two straight lines intersect. In this case, many first electrodes 14 are in contact with the conductor 12 in any of the openings 17. For this reason, when a voltage is applied between the first electrode 14 and the second electrode 16, the light emitting layer included in the organic compound layer 15 positioned on almost all the first electrodes 14 emits light, and the light emitting layer emits light. The area ratio of the portion to be increased.

On the other hand, FIG. 2B shows an example in which the opening 17 having a rectangular planar shape and the first electrode 14 having a rectangular planar shape are arranged with their long axes substantially parallel to each other. In this case, the number of first electrodes 14 that are not in contact with the conductor 12 (electrically isolated) in the opening 17 increases. That is, the first electrode 14 that is electrically connected to the conductor 12 in the opening 17 and the first electrode 14 that is not electrically connected to the conductor 12 are mixed. For this reason, since the light emitting layer included in the organic compound layer 15 located on the first electrode 14 not electrically connected to the conductor 12 does not emit light, the area ratio of the light emitting portion in the light emitting layer is reduced.

Further, in FIG. 2C, the opening 17 having a rectangular planar shape and the first electrode 14 having a rectangular planar shape are arranged so that the angle formed by the major axes of each other is 45 degrees. An example is shown. In this case, the number of the first electrodes 14 electrically connected to the conductor 12 in the opening 17 is intermediate between the case of FIG. 2A and the case of FIG. 2B, and the area of the light emitting portion in the light emitting layer. The ratio is also between them.

As described above, in the present embodiment, by changing the relative arrangement of the plurality of openings 17 having an elongated shape and the plurality of first electrodes 14 having an elongated shape in different sections, It is possible to control the area ratio of the light emitting portion in the light emitting layer of the partition. Specifically, by changing the angle (θ) formed by the first major axis of the opening 17 and the second major axis of the first electrode 14 within a range of 0 degrees to 90 degrees for each section, The light emission luminance for each section can be changed greatly.

FIG. 3 is a diagram for explaining an example in which the direction of the first electrode 14 changes depending on the distance from the terminal portion in the light emitting region in the light emitting device to which the present embodiment is applied. In the present embodiment, a method is used in which the angle (θ) formed by the opening 17 and the first electrode 14 is changed within a range of 0 ° to 90 ° to control the area ratio of the light emitting portion in the light emitting layer. Thus, the light emission luminance of the entire light emitting region including a plurality of sections is controlled. Note that the present embodiment is not limited to this.

As shown in FIG. 3, in the light emitting device according to the present embodiment, a terminal portion 18 for connecting to a power source is formed at least at a part outside the light emitting region. At this time, when the conductor 12 is a transparent conductive film made of a metal oxide such as ITO or IZO, the voltage drop due to the internal resistance of the conductor 12 causes a portion farther from the terminal portion in the light emitting region per unit area. The brightness decreases.

Therefore, the light emitting region is divided into a plurality of sections (in FIG. 3, three sections (section 1, section 2, section 3)), and the area ratio of the light emitting portion in the light emitting layer becomes larger as the section is farther from the terminal portion 18. Further, by setting the angle θ (that is, the angle formed between the direction of the first major axis in the opening 17 and the direction of the second major axis in the first electrode 14) in each section, The brightness can be made uniform.

For example, in the case of FIG. 3, there are section 1, section 2, and section 3 from the side closer to the terminal portion 18, and the angles θ in these sections are 0 degrees, 45 degrees, and 90 degrees, respectively. The area ratio of the light emitting portion in the light emitting layer increases in this order. Therefore, by increasing the angle θ within the range of 0 ° to 90 °, the farther from the terminal portion 18, the luminance decrease due to the voltage drop due to the internal resistance of the conductor 12 is offset, and the light emitting region The brightness inside can be made uniform.

The preferable size of the shape of the opening 17 and the first electrode 14 viewed from the direction perpendicular to the substrate 11 is visually recognized as a continuous light emitting surface in the plurality of sections, and the light emitting device. Is determined from the viewpoint of easy manufacture. In the present embodiment, for example, the length of the first short axis of the opening 17 and the length of the second short axis of the first electrode 14 are each preferably in the range of 0.1 μm to 10 μm. .
From the viewpoint that it is easy to control the luminance by changing the angle (θ) formed by the first long axis of the opening 17 and the second long axis of the first electrode 14, the first of the opening 17. The major axis of the first electrode 14 and the length of the second major axis of the first electrode 14 are not less than five times the length of the first minor axis of the opening 17 and the second minor axis of the first electrode 14, respectively. It is preferable.
Further, in each of the plurality of sections, the distance between the openings 17 in the first minor axis direction of the openings 17 is shorter than the length of the second major axis of the first electrode 14, and It is preferable that the length is longer than the length of the second short axis because it is easier to control the luminance.
In the present embodiment, it is preferable that about 10 ² to 10 ^{8 of} these openings 17 and first electrodes 14 are formed in an arbitrary 1 mm square region of the light emitting region.

(Planar shape of the first electrode 14 and the opening 17)
Here, the planar shape of the first electrode 14 and the opening 17 is not limited to a rectangle as shown in FIGS. 2A and 2B, but is preferably an elongated shape. Next, examples of the planar shape of the first electrode 14 and the opening 17 will be described.

FIG. 4 is a diagram for explaining an example of the planar shape of the first electrode 14 and the opening 17.
As described above, the planar shape of the first electrode 14 and the opening 17 is not limited to a rectangle, but is preferably an elongated shape. Examples of elongated shapes including a rectangle include, for example, a rectangle (FIG. 4A), an ellipse (FIG. 4B), a rhombus (FIG. 4C), and a parallelogram (FIG. 4D). , Triangles (FIGS. 4E and 4F), trapezoids (FIGS. 4G and 4H), and the like.
When the first electrode 14 and the opening 17 have such an elongated shape, the directions of the first major axis of the opening 17 and the second major axis of the first electrode 14 are strictly defined for all shapes. Although not necessarily required, the shape may be along the longitudinal direction of each shape. For example, the shapes shown in FIGS. 4A to 4H are defined as follows.

For elongated rectangular as shown in FIG. 4 (a), the first major axis x _a a first short axis y _a of the opening 17 are each long side and short side, a first long axis x _a length and the length of the first short axis y _a of is defined as the length of the long and short side of each long side.
Similarly, the second major axis x _a and the second short axis y _a of the first electrode 14 are each long side and short side, the length and the second short axis y of the second major axis x _a the length of _a is defined as the length of the long and short side of each long side.

For oval shown in FIG. 4 (b), the first major axis x _b and the first short axis y _b of the opening 17, respectively coincide with the major and minor axes of the ellipse, the first length the length of the axis x _b of the length of the first short axis y _b are defined respectively major axis and a minor axis.
Similarly, the second major axis x _b and the second short axis y _b of the first electrode 14, respectively coincide with the major and minor axes of the ellipse, the second major axis x _b length and the second the length of the minor axis y _b are defined respectively major axis and a minor axis.

For elongated rhombus shown in FIG. 4 (c), the first major axis x _c of the opening 17 is a line segment connecting the two acute vertices of the first short axis y _c is two obtuse Is defined as the line connecting the vertices.
Similarly, the second is the long axis x _c of the first electrode 14, a line segment connecting the two acute vertices of the second short axis y _c is, if it is a line segment connecting two obtuse apex of the Defined.

For elongated parallelogram shown in FIG. 4 (d), the first major axis x _d of the opening 17 is long side direction of the first short axis y _d in the first major axis x _d a direction orthogonal, its length is defined as the width of the parallelogram in the direction of the first short axis y _d.
Similarly, the second major axis x _d of the first electrode 14 is a long side, the direction of the second short axis y _d is a direction orthogonal to the first long axis x _d, the length a it is defined as the width of the parallelogram in the two directions of the minor axis y _d.

For base short elongated isosceles triangle shown in FIG. 4 (e), the first major axis x _e of the opening 17, a line segment connecting the intersection of the perpendicular bisector and isosceles triangle apex angle , and the first short axis y _e is defined to be the base.
Similarly, the second major axis x _e of the first electrode 14 is a line segment connecting the intersection of the perpendicular bisector and isosceles triangle of the apex angle, the second short axis y _e is the base Is defined.

If the apex angle as shown in FIG. 4 (f) is obtuse elongated isosceles triangle, the first long axis x _f of the opening 17 is the bottom, the midpoint of the first short axis y _f vertex and base Is defined as a line segment connecting
Similarly, the second major axis x _f of the first electrode 14 is bottom side is defined as a second short axis y _f a line segment connecting the midpoint of the vertices and bottom.

In the case of an elongated trapezoidal shape having a short upper base and lower bottom as shown in FIG. 4G, the first major axis _xg of the opening 17 is between the upper base and the lower base among the vertical lines of the upper base (lower base). And the first short axis y _g is defined as the longer side of the upper and lower bases.
Similarly, the second major axis x _g of the first electrode 14 is a line segment existing between the upper base and the lower base among the vertical lines of the upper base (lower base), and the second short axis y _g is , The longer side of the upper and lower bases.

In the case of an elongated trapezoid with a long upper base and lower base shown in FIG. 4H, the first major axis x _h of the opening 17 is the longer side of the upper base and the lower base, and the first minor axis y _h of, among the perpendicular of the upper base (lower base) is defined as a line segment that exists between the upper base and the lower base.
Similarly, the second major axis x _h of the first electrode 14 is the longer side of the upper and lower bases, and the second minor axis y _h is the perpendicular of the upper base (lower base). Of these, it is defined as a line segment that exists between the upper and lower bases.

Note that the lengths of the first major axis (or second major axis) and the first minor axis (or second minor axis) in an elongated shape other than the shape shown in FIG. Although not strictly defined, for example, it is defined as the maximum width of the shape in each axial direction.

(Method for forming opening 17)
Examples of the method for forming the opening 17 include a method using photolithography. In order to perform this method, first, a resist solution is applied on the insulating layer 13, and the excess resist solution is removed by spin coating or the like to form a resist layer. Then, a mask on which a predetermined pattern for forming the opening 17 is drawn is applied, and exposure is performed using ultraviolet (UV), electron beam (EB), or the like.

Here, if the same-size exposure (for example, in the case of contact exposure or proximity exposure) is performed, a pattern of the opening 17 that is the same size as the mask pattern is formed. If reduced exposure (for example, exposure using a stepper) is performed, the pattern of the opening 17 reduced with respect to the mask pattern is formed. Next, when the exposed portion of the resist layer is removed using a developer, the resist layer in the pattern portion is removed.

Next, the exposed portion of the insulating layer 13 (and the portion of the conductor 12 in some cases) is removed by etching to form an opening 17. As the etching, either dry etching or wet etching can be used. As dry etching, reactive ion etching (RIE) using inductively coupled plasma or capacitively coupled plasma can be used. As wet etching, a method of immersing in dilute hydrochloric acid or dilute sulfuric acid can be used. it can. Note that when etching is performed, a layer through which the opening 17 passes can be selected by adjusting etching conditions (processing time, gas used, pressure, substrate temperature).

The patterning of the opening 17 may be performed at the same time as the formation of the insulating layer 13. The film can be formed by a film forming method such as a printing method for drawing the insulating layer 13 while leaving the pattern of the opening 17.

(Patterning method of the first electrode 14)
As a patterning method for the first electrode 14, a method such as photolithography can be used in the same manner as the method for forming the opening 17 described above. The patterning of the first electrode 14 may be performed simultaneously with the film formation or after the film formation.

In the light emitting device to which the present embodiment is applied, the angle θ formed by the direction of the first major axis in the opening 17 and the direction of the second major axis in the first electrode 14 is within one section. Although constant, the angle θ is not constant over all sections in the light emitting area. That is, the light emitting region includes at least two sections having different angles θ.

For example, when patterning the first electrode 14 or the opening 17 using photolithography, the angle θ can be easily changed by changing the relative angle between the substrate 11 and the photomask. Thereby, in the light-emitting device of this Embodiment, the brightness | luminance in a light emission area | region can be controlled easily.

That is, patterning can be performed more easily by patterning all the light emitting regions at once or by performing the patterning for each section. Further, if the first long axes are formed so as to be parallel to each other in all of the openings 17 in the light emitting region, the patterning of the openings 17 is easy, and the luminance is controlled by changing the angle θ. Is preferable because it is easy.

Conversely, when all the first electrodes 14 in the light emitting region are formed so that the second major axes are parallel to each other, the patterning of the first electrode 14 is easy, and the brightness is obtained by changing the angle θ. Is preferable because it can be easily controlled.

In patterning using a mask such as photolithography, by making the pattern of the plurality of openings 17 and the plurality of first electrodes 14 the same for a plurality of sections, each section can be patterned using the same mask. Easy to manufacture.
Here, the patterns of the plurality of openings 17 and the plurality of first electrodes 14 are the same between the sections. The shape and size of the openings 17 and the first electrodes 14, the positions of the openings 17 and the first The interval between the electrodes 14 is the same in any section, and the direction of the first major axis in the opening 17 and the second major axis in the first electrode 14 may be different for each section.

In addition, in order to use the light-emitting device of this embodiment stably for a long period of time, it is preferable to attach a protective layer or a protective cover for protecting the light-emitting device from the outside. As the protective layer, a polymer compound, metal oxide, metal fluoride, metal boride, silicon nitride, silicon oxide, or the like can be used. And these laminated bodies can also be used. Further, as the protective cover, a glass plate, a plastic plate whose surface has been subjected to low water permeability treatment, a metal, or the like can be used. For such a protective cover, it is preferable to employ a method in which a thermosetting resin, a photocurable resin, frit glass, or the like is attached to the element substrate and sealed.

Further, at this time, it is preferable to arrange a spacer between the substrate 11 and the protective cover because a predetermined space can be secured between the light emitting unit 10 and the protective cover and the light emitting unit can be prevented from being damaged. Then, by filling an inert gas such as nitrogen, argon, or helium in such a space, it becomes easy to prevent the upper second electrode 16 from being oxidized. In particular, it is preferable to use helium because heat conduction is high, and thus heat generated from the light emitting device when voltage is applied can be effectively transmitted to the protective cover. Furthermore, by installing a desiccant such as barium oxide in such a space, it becomes easy to suppress the moisture adsorbed in the series of manufacturing steps from damaging the light emitting device.

The light emitting device of this embodiment can be used for a surface emitting light source or the like. Specifically, it is suitably used for backlights, electrophotography, illumination, resist exposure, reading devices, interior illumination, optical communication systems and the like in display devices.

DESCRIPTION OF SYMBOLS 10 ... Light emission part, 11 ... Board | substrate, 12 ... Conductor, 13 ... Insulating layer, 14 ... 1st electrode, 15 ... Organic compound layer, 16 ... 2nd electrode, 17 ... Opening part, 18 ... Terminal part

Claims

A light emitting device having a light emitting region composed of a plurality of minute light emitting units electrically connected in parallel,
In the light emitting region, the light emitting device includes:
One planar conductor;
An insulating layer formed on the upper surface of the planar conductor;
A plurality of openings formed in the insulating layer;
A plurality of first electrodes formed on the insulating layer;
An organic compound layer including a light emitting layer formed to cover the plurality of first electrodes;
A second electrode formed on the organic compound layer,
Each comprising a plurality of compartments including two or more of the first electrodes,
At least a part of the plurality of first electrodes is also formed in the opening and electrically connected to the conductor, thereby forming an electrode for energizing the organic compound layer in the plurality of minute light emitting portions,
The plurality of openings have an elongated shape having a first major axis and a first minor axis that are orthogonal to each other in a plan view, and the first major axes are parallel to each other in one of the compartments. Formed to be
The plurality of first electrodes have an elongated shape having a second major axis and a second minor axis that are orthogonal to each other in plan view, and the second major axes are parallel to each other in one of the compartments. Formed to be
In each of the plurality of sections, a distance between the openings in the direction of the first short axis of the opening is shorter than a length of the second long axis of the first electrode, and the first electrode Longer than the length of the second short axis of
The plurality of sections include at least two different angles between the first major axis of the opening and the second major axis of the first electrode in each of the plurality of sections. A light emitting device comprising a compartment.
2. The first electrode electrically connected to the conductor and the first electrode not electrically connected to the conductor are mixed in the light emitting region. The light emitting device according to 1.
3. The device according to claim 1, wherein one of the first long axis of the opening and the second long axis of the first electrode is parallel to each other in the light emitting region. Light emitting device.
The lengths of the first major axis of the opening and the second major axis of the first electrode are respectively the first minor axis of the opening and the second minor axis of the first electrode. The light emitting device according to any one of claims 1 to 3, wherein the light emitting device is at least five times the length of the light emitting device.
The shape and size of the plurality of openings are all the same and / or the shape and size of the plurality of first electrodes are all the same in the light emitting region. The light emitting device according to claim 1.
The arrangement pattern of the plurality of openings and the arrangement pattern of the plurality of first electrodes are the same for each of the plurality of sections, and only the angle formed by the first major axis and the second major axis is different. The light-emitting device according to claim 5.
The length of the first short axis and the length of the second short axis of the opening are 0.1 μm to 10 μm, respectively, and the opening and the first electrode are each 1 mm of the light emitting region. the light emitting device according to any one of claims 1 to 6, characterized in that it is 10 2, respectively to 10 8 formed in the square region.
The one of the plurality of openings and the plurality of first electrodes is formed in such a manner that the long axes face each other in parallel and periodically in the light emitting region. 8. The light emitting device according to any one of 1 to 7.
The planar conductor is a transparent conductive film made of a metal oxide, and is electrically connected to at least a part of the outer side of the light emitting region with the planar conductor and connected to a power source. And the angle formed by the first long axis of the opening and the second long axis of the first electrode is such that the area ratio of the light emitting portion in the section is far from the terminal portion. The light-emitting device according to claim 1, wherein the light-emitting device is set to be larger as the section is larger.
10. The light emitting device according to claim 9, wherein the angle is larger as the section is farther from the terminal portion.