JP2014225329A - Light-emitting device, display device, and illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device, a display device, and an illuminating device, capable of efficiently emitting light originated from an organic light-emitting layer toward the exterior, and of emitting light at a high luminance.SOLUTION: A bank (an insulating layer) 15 sectionalizing a first electrode (a lower electrode) 12 into a plurality of sections for each predetermined region (e.g., each pixel) is composed of a material having at least light reflectivity. It is preferred that a material having a white color tone is used as the material having the light reflectivity. Further, it is also preferred that a material having light diffusivity as well as the light reflectivity is used.

Description

   The present invention relates to a light emitting device that emits light by applying a voltage to an organic light emitting layer, and a display device and an illumination device including the light emitting device.

   In recent years, the need for flat panel displays has increased with the advancement of sophistication in society. Examples of the flat panel display include a non-self-luminous liquid crystal display (LCD), a self-luminous plasma display (PDP), an inorganic electroluminescence (inorganic EL) display, and organic electroluminescence (hereinafter, “organic EL”). Or a display or the like.

Among these flat panel displays, light-emitting elements using organic light-emitting layers, such as organic EL (Organic light emitting diode) displays, are attracting attention as candidate technologies that can become the mainstream of next-generation displays due to their features such as thinness and wide viewing angle. Has been.
On the other hand, the organic EL still has problems such as low luminous efficiency, large power consumption, short lifetime, and low reliability. The luminous efficiency is generally represented by ηφ (ext) (External Quantum Efficiency) = ηext × ηφ = ηext × γ × ηr × φf. Here, ηφ (ext) is external quantum efficiency, ηext is external light extraction efficiency, ηφ is internal quantum efficiency, γ is carrier balance, ηr is exciton generation probability, and φf is fluorescence quantum yield.

   In recent years, the internal quantum efficiency has been steadily improved with the progress of materials, and in particular, has been greatly improved with the progress of phosphorescent materials utilizing triplet states. However, light extraction efficiency remains a major issue. In the organic EL element, since the refractive index of the organic light emitting layer, the transparent electrode layer, the glass substrate, and the like used is larger than that of air, light cannot be efficiently extracted from the total reflection condition based on Snell's law. The amount of light that can be extracted is usually about 15 to 30%, and most of the light is lost without being emitted to the outside.

For example, Patent Document 1 discloses an invention in which a low refractive index layer having a refractive index in the range of 1.01 to 1.3 is provided on the surface of the transparent conductive layer opposite to the light emitting layer. Yes.
In Patent Document 2, a leaching light diffusion layer in which particles that scatter light are diffused in a matrix resin made of a low refractive index material is provided between a transparent electrode layer and a light-transmitting substrate. The invention is disclosed.
Patent Document 3 discloses an invention in which a light extraction layer composed of a large number of fine particles is provided on a substrate surface on the light extraction side.
Further, Patent Document 4 discloses an invention in which the light extraction efficiency is improved by making the pixel into a concave structure.
Patent Document 5 discloses an invention in which the light extraction efficiency is improved by providing a reflective layer on the side surface of a pixel.
Patent Document 6 discloses that in an organic EL element in which a phosphor layer is combined with an organic EL light emitting unit, a reflective film is provided on the side surface of the phosphor layer.

JP 2002-278477 A JP 2004-296437 A JP 2011-108395 A JP 2011-009017 A JP 2010-009793 A JP 11-329726 A

  However, although the inventions disclosed in Patent Documents 1 to 4 described above can improve the light extraction efficiency, there is a problem that the effect of improving the light extraction efficiency is limited. In other words, no measures have been taken against the fact that light propagates along the surface direction through the organic light emitting layer or the electrode and the light emitted to the outside decreases.

  For example, the typical refractive index of an organic light emitting layer is about 1.8, the typical refractive index of an insulating layer (bank) is about 1.5 to 1.8, and the typical refractive index of ITO which is a transparent electrode layer Is about 2.1 to 2.2, and is totally reflected at the interface with the low refractive index layer due to the difference in refractive index from the low refractive index layer (with a refractive index of about 1.0 to 1.3). There are many ingredients that end up. The totally reflected component propagates along the surface direction through the organic light emitting layer, the insulating layer, the transparent electrode layer, and the like, and is lost without being emitted to the outside.

Insulating layer for partitioning the transparent electrode layer in each pixel region of the organic light emitting layer (bank) is conventionally polymethyl methacrylate, is composed of a polymer material or an inorganic material such as SiO _2, such as polyimide, or color transparent It was black. For this reason, when the insulating layer (bank) is black, the light spread along the surface direction is absorbed by the insulating layer and lost. Further, when the insulating layer (bank) is transparent (light transmissive), light propagates toward the adjacent organic light emitting layer or transparent electrode layer through the insulating layer and is lost.

  Patent Documents 5 and 6 disclose a technique for improving the light extraction efficiency by forming a reflection film on the side surface of the light emitting portion. Further, Patent Document 6 discloses metal powder, metal particles as the reflection film. Alternatively, it is disclosed that the resin is made of a resin containing a white pigment, but there are structural and process problems.

  In the technique of Patent Document 5, since the reflective film on the side surface is conductive, it is necessary to further provide an insulating layer in the form of a reflective film, and there is a drawback that the process becomes complicated. In addition, since the portion where the reflective film is formed is the side wall of the partition wall that is inclined with respect to the substrate, not only is the process controllability during production difficult, but also the exposure alignment margin for pattern formation In view of the above, there is a problem that the pixel opening becomes small. When the pixel opening is small, it is necessary to increase the light emission luminance at the pixel opening in order to obtain a desired luminance as a display.

In the technique of Patent Document 6, a technique for forming a reflective film on the side surface of the phosphor layer and a technique made of a resin containing metal powder, metal particles, or a white pigment as the reflective film are disclosed. There is no disclosure or suggestion about application to the light emitting part. Further, when this technique is applied to an organic EL light emitting unit and a reflective film is formed on the side surface of the organic light emitting unit, structural problems arise in terms of structure.
First, the organic material used for the light emitting portion of the organic EL is extremely weak against moisture, oxygen, solvent, etc., and it is extremely difficult to form a reflective film on the side surface of the organic EL light emitting portion. In addition, this technique has a problem that it cannot be applied to a structure in which the light emitting layer is formed on the entire surface without being separated for each pixel, regardless of whether the light emitting layer is separately formed for each pixel of the organic EL. Furthermore, when considering the optical loss due to the optical waveguide from the organic EL light emitting part, it is necessary to consider the waveguide from other than the light emitting part such as an electrode. However, Patent Document 6 does not disclose or suggest any of them. .

   The present invention has been made in view of the above circumstances, and provides a light emitting device, a display device, and a lighting device that can efficiently emit light emitted from an organic light emitting layer toward the outside and emit light with high luminance. The purpose is to do.

In order to solve the above problems, some aspects of the present invention provide the following light emitting device, display device, and lighting device.
That is, the light-emitting device of the present invention includes a first electrode and a second electrode that are sequentially stacked on one surface of a light-transmitting substrate, and an organic light-emitting layer formed between the first electrode and the second electrode. A light emitting device comprising:
A bank for partitioning at least the first electrode into a plurality of predetermined areas is provided, and the bank is made of a material having light reflectivity.

The second electrode is made of a light-shielding material.
The first electrode is made of a light transmissive material.

The bank is made of a white material.
Further, the bank is made of a material having light diffusibility in addition to light reflectivity.

The bank is characterized in that fine light reflective particles are dispersed in a resin.
The light-reflecting particles have a particle size of 200 nm to 5 μm.

   A low refractive index layer having a refractive index lower than that of the substrate is further formed between the substrate and the first electrode.

   The display device of the present invention is characterized in that a drive unit for controlling light emission of the light emitting device is arranged for the light emitting device described in each of the above items.

   The illuminating device of the present invention is characterized in that a drive unit that controls light emission of the light-emitting device is arranged for the light-emitting device described in the above items.

   According to the present invention, it is possible to provide a light emitting device, a display device, and a lighting device with high luminous efficiency (high luminance).

It is sectional drawing which shows the light-emitting device which concerns on 1st embodiment of this invention. It is sectional drawing which shows the light-emitting device which concerns on 2nd embodiment of this invention. It is sectional drawing which shows the light-emitting device which concerns on 3rd embodiment of this invention. It is sectional drawing which shows the light-emitting device which concerns on 4th embodiment of this invention. It is sectional drawing which shows the light-emitting device which concerns on 5th embodiment of this invention. It is sectional drawing which shows the display apparatus which concerns on 6th embodiment of this invention. It is sectional drawing which shows the display apparatus which concerns on 7th embodiment of this invention. It is sectional drawing which showed the example of the shape of a bank. It is sectional drawing which showed the structural example of the bank. It is sectional drawing which shows the light-emitting device which concerns on 8th embodiment of this invention. It is sectional drawing which shows the modification of 8th embodiment. It is an external view which shows the display apparatus which is one application example of the light-emitting device of this invention. It is an external view which shows the illuminating device which is one application example of the light-emitting device of this invention. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which shows the light-emitting device which concerns on the modification of 8th embodiment. It is sectional drawing which showed the shape variation of the bank.

  Hereinafter, an embodiment of a light-emitting device, a display device, and an electronic apparatus according to the present invention will be described with reference to the drawings. The following embodiments are specifically described for better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for the sake of convenience. Not necessarily.

(Light emitting device: first embodiment)
FIG. 1 is a schematic sectional view showing a light emitting device according to the first embodiment.
The light emitting device 10 includes a light transmissive substrate 11, a first electrode (lower electrode) 12, a second electrode (upper electrode) 13, a first electrode 12, An organic light emitting layer 14 formed between the two electrodes 13.

   A bank (insulating layer) 15 that partitions the first electrode 12 into a plurality of predetermined regions is formed on the one surface 11 a of the substrate 11. Such a bank 15 divides the first electrode 12 into a plurality of parts corresponding to a region corresponding to one pixel of the organic light emitting layer 14, for example, and electrically insulates the divided first electrodes 12 from each other. .

   As a manufacturing process, for example, a process of forming a first electrode (lower electrode) 12 on a substrate 11, then forming a bank 15, and further forming an organic light emitting layer 14 and a second electrode (upper electrode) 13. Can be used. Since the material used for the organic EL is extremely weak against moisture, oxygen and the like, a sufficient dehydration step (baking step, bake step, and so on) is performed before the organic light emitting layer 14 is formed, that is, after the first electrode (lower electrode) 12 and the bank 15 are formed. It is preferable to perform a vacuum drying step or the like.

   The substrate 11 is made of a light transmissive material such as glass or transparent resin. As a specific example, a 0.7 mm thick glass substrate frequently used in a liquid crystal display or the like can be used.

   The first electrode (lower electrode) 12 may be a transparent electrode. For example, ITO (Indium-tin-oxide), ZnO (Zinc oxide), or the like is used. The thickness of the first electrode 12 is, for example, about 100 nm. The first electrode 12 is usually an anode, but may be a cathode. In that case, a material having a low work function is used. In addition, auxiliary wiring may be provided for the purpose of reducing wiring resistance. The auxiliary wiring can be formed of a metal material such as Al, Ag, Ta, Ti, Ni, for example.

   The first electrode (lower electrode) 12 is divided into a plurality for each predetermined region by a bank (insulating layer) 15. When the light-emitting device of the present invention is used as a display device (organic EL display), the first electrode (lower electrode) 12 may be partitioned for each region corresponding to one pixel.

   The second electrode (upper electrode) 13 may be light-shielding or light-transmissive. When the second electrode (upper electrode) 13 is light-opaque such as light-shielding or reflective, a so-called bottom emission type light-emitting device is obtained. When the second electrode (upper electrode) 13 is light transmissive, a double-sided light emitting device is obtained. The second electrode 13 normally forms a cathode, and LiF / Al, MgAg / Al, Ba / Al, Ca / Ag, or the like can be used in the case of light impermeability. In the case of light transmittance, LiF / ITO, MgAg / IZO, or the like can be used. Note that the second electrode (upper electrode) 13 may be an anode, and in this case, a material having a high work function, such as ITO, is preferably used.

In addition to these, various known electrode materials can be used as the electrode material for forming the first electrode 12 and the second electrode 13. In the case of an anode, a metal such as gold (Au), platinum (Pt), nickel (Ni) or the like having a work function of 4.5 eV or more from the viewpoint of more efficiently injecting holes into the organic light emitting layer 14. And oxide (ITO) made of indium (In) and tin (Sn), oxide of tin (Sn) (SnO ₂ ), oxide made of indium (In) and zinc (Zn) (IZO), etc. are transparent It is mentioned as an electrode material.

   Moreover, as an electrode material for forming the cathode, lithium (Li), calcium (Ca), cerium (Ce) having a work function of 4.5 eV or less from the viewpoint of more efficiently injecting electrons into the organic light emitting layer 14. And metals such as barium (Ba) and aluminum (Al), or alloys such as Mg: Ag alloy and Li: Al alloy containing these metals.

   The first electrode 12 and the second electrode 13 can be formed using the above materials by a known method such as an EB vapor deposition method, a sputtering method, an ion plating method, a resistance heating vapor deposition method, etc. The forming method is not limited. If necessary, the formed electrode can be patterned by a photolithographic fee method or a laser peeling method, or a patterned electrode can be directly formed by combining with a shadow mask. The film thickness is preferably 50 nm or more. When the film thickness is less than 50 nm, the wiring resistance is increased, which may increase the drive voltage.

   The organic light emitting layer (organic EL light emitter) 14 emits light in a predetermined wavelength band by a voltage applied between the first electrode 12 and the second electrode 13. Although the organic light emitting layer (organic EL light emitter) 14 may be a single layer, it is usually composed of a plurality of layers. For example, a laminated film of α-NPD and Alq3 can be used. Further, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, between a first electrode (lower electrode) 12 serving as an anode and a second electrode (upper electrode) 13 serving as a cathode, It is also practiced to form a multi-layered organic light emitting layer composed of an electron injection layer or the like.

In addition to these layers, it has been actively studied to use various layers such as a MoO ₃ layer, a C ₆₀ layer, a fullerene-containing layer, and a quantum dot-containing layer, and it goes without saying that the present invention can be applied to any of these layers. A light emitting element using a quantum dot-containing layer is called a QLED (Quantum-dot light emitting diode). A so-called tandem structure in which light emitting regions are stacked can also be used. As for the film thickness of the layer arrange | positioned between the 1st electrode 12 and the 2nd electrode 13, each layer is about several tens of nm normally. Needless to say, the technology of the present invention can be applied to a light-emitting element that has not yet been invented or a light-emitting element that is not generally recognized as long as the configuration of the present invention is adopted.

Specific examples of the layer structure of the organic light emitting layer 14 include the following configurations, but the present invention is not limited thereto.
(1) Organic light emitting layer (2) Hole transport layer / organic light emitting layer (3) Organic light emitting layer / electron transport layer (4) Hole transport layer / organic light emitting layer / electron transport layer (5) Hole injection layer / Hole transport layer / organic light emitting layer / electron transport layer (6) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer (7) Hole injection layer / hole transport layer / organic Light-Emitting Layer / Hole Prevention Layer / Electron Transport Layer (8) Hole Injection Layer / Hole Transport Layer / Organic Light-Emitting Layer / Hole Prevention Layer / Electron Transport Layer / Electron Injection Layer (9) Hole Injection Layer / Hole Transport layer / electron prevention layer / organic light emitting layer / hole prevention layer / electron transport layer / electron injection layer Here, organic light emission layer, hole injection layer, hole transport layer, hole prevention layer, electron prevention layer, electron Each of the transport layer and the electron injection layer may have a single layer structure or a multilayer structure.

   The organic light emitting layer 14 may be composed of only the organic light emitting material exemplified below, or may be composed of a combination of a light emitting dopant and a host material, and optionally, a hole transport material, an electron transport material, Additives (donor, acceptor, etc.) may be included, and these materials may be dispersed in a polymer material (binding resin) or an inorganic material. From the viewpoint of luminous efficiency and lifetime, those in which a luminescent dopant is dispersed in a host material are preferable.

As the organic light emitting material, a known light emitting material for an organic light emitting layer can be used. Such light-emitting materials are classified into low-molecular light-emitting materials, polymer light-emitting materials, and the like. Specific examples of these compounds are given below, but the present invention is not limited to these materials. The light-emitting material may be classified into a fluorescent material, a phosphorescent material, and the like, and it is preferable to use a phosphorescent material with high light emission efficiency from the viewpoint of reducing power consumption.
Here, specific compounds are exemplified below, but the present invention is not limited to these materials.

As a luminescent dopant arbitrarily contained in the light emitting layer, a known dopant material for an organic light emitting layer can be used. Examples of such dopant materials include, for example, p-quaterphenyl, 3,5,3,5 tetra-t-butylsecphenyl, 3,5,3,5 tetra-t-butyl-p. -Fluorescent materials such as quinckphenyl. Fluorescent light-emitting materials such as styryl derivatives, bis [(4,6-difluorophenyl) -pyridinato-N, C2 ′] picolinate iridium (III) (FIrpic), bis (4 ′, 6′-difluorophenyl) And phosphorescent organometallic complexes such as polydinato) tetrakis (1-pyrazoyl) borate iridium (III) (FIr ₆ ).

   Moreover, as a host material when using a dopant, a well-known host material for organic EL can be used. As such a host material, the above-described low molecular light emitting material, polymer light emitting material, 4,4′-bis (carbazole) biphenyl, 9,9-di (4-dicarbazole-benzyl) fluorene (CPF), 3 , 6-bis (triphenylsilyl) carbazole (mCP), carbazole derivatives such as (PCF), aniline derivatives such as 4- (diphenylphosphoyl) -N, N-diphenylaniline (HM-A1), 1,3- And fluorene derivatives such as bis (9-phenyl-9H-fluoren-9-yl) benzene (mDPFB) and 1,4-bis (9-phenyl-9H-fluoren-9-yl) benzene (pDPFB).

   The charge injection / transport layer is used to more efficiently inject charges (holes, electrons) from the electrode and transport (injection) to the light emitting layer, and the charge injection layer (hole injection layer, electron injection layer). It is classified as a transport layer (hole transport layer, electron transport layer), and may be composed only of the charge injection transport material exemplified below, and may optionally contain additives (donor, acceptor, etc.) These materials may be dispersed in a polymer material (binding resin) or an inorganic material.

   As the charge injecting and transporting material, a known charge transporting material for the organic light emitting layer can be used. Such charge injecting and transporting materials are classified into hole injecting and transporting materials and electron injecting and transporting materials. Specific examples of these compounds are given below, but the present invention is not limited to these materials.

Examples of the hole injection / hole transport material include oxides such as vanadium oxide (V ₂ O ₅ ) and molybdenum oxide (MoO ₂ ), inorganic p-type semiconductor materials, porphyrin compounds, N, N′-bis (3 -Methylphenyl) -N, N′-bis (phenyl) -benzidine (TPD), N, N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine (NPD), etc. Low molecular weight materials such as tertiary amine compounds, hydrazone compounds, quinacridone compounds, styrylamine compounds, polyaniline (PANI), polyaniline-camphor sulfonic acid (PANI-CSA), 3,4-polyethylenedioxythiophene / polystyrene sulfonate ( PEDOT / PSS), poly (triphenylamine) derivative (Poly-TPD), polyvinylcarbazole (PVC) z), polymer materials such as poly (p-phenylene vinylene) (PPV), poly (p-naphthalene vinylene) (PNV), and the like.

   In addition, in terms of more efficient injection and transport of holes from the anode, the material used for the hole injection layer is the highest occupied molecular orbital (HOMO) than the hole injection transport material used for the hole transport layer. It is preferable to use a material having a low energy level, and as the hole transport layer, it is preferable to use a material having higher hole mobility than the hole injection transport material used for the hole injection layer.

   In order to further improve the hole injection / transport property, it is preferable to dope the hole injection / transport material with an acceptor. As an acceptor, the well-known acceptor material for organic light emitting layers can be used. Although these specific compounds are illustrated below, this invention is not limited to these materials.

Acceptor materials include Au, Pt, W, Ir, POCl ₃ , AsF ₆ , Cl, Br, I, vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₂ ), and other inorganic materials, TCNQ (7, 7 , 8,8, -tetracyanoquinodimethane), TCNQF ₄ (tetrafluorotetracyanoquinodimethane), TCNE (tetracyanoethylene), HCNB (hexacyanobutadiene), DDQ (dicyclodicyanobenzoquinone), etc. And compounds having a nitro group such as TNF (trinitrofluorenone) and DNF (dinitrofluorenone), and organic materials such as fluoranyl, chloranil and bromanyl. Among these, compounds having a cyano group such as TCNQ, TCNQF ₄ , TCNE, HCNB, DDQ and the like are more preferable because they can increase the carrier concentration more effectively.

Examples of electron injection / electron transport materials include inorganic materials that are n-type semiconductors, oxadiazole derivatives, triazole derivatives, thiopyrazine dioxide derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, diphenoquinone derivatives, fluorenone derivatives, benzodifuran derivatives. And low molecular weight materials such as poly (oxadiazole) (Poly-OXZ) and polystyrene derivatives (PSS). In particular, examples of the electron injection material include fluorides such as lithium fluoride (LiF) and barium fluoride (BaF ₂ ), and oxides such as lithium oxide (Li ₂ O).

   The material used for the electron injection layer is a material having an energy level of the lowest unoccupied molecular orbital (LUMO) higher than that of the electron injection / transport material used for the electron transport layer, in order to more efficiently inject and transport electrons from the cathode. It is preferable to use a material having a higher electron mobility than the electron injecting and transporting material used for the electron injecting layer.

   In order to further improve the electron injection / transport property, it is preferable to dope the electron injection / transport material with a donor. As the donor, a known donor material for an organic light emitting layer can be used. Although these specific compounds are illustrated below, this invention is not limited to these materials.

   Donor materials include inorganic materials such as alkali metals, alkaline earth metals, rare earth elements, Al, Ag, Cu, and In, anilines, phenylenediamines, benzidines (N, N, N ′, N′-tetraphenyl) Benzidine, N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine, N, N′-di (naphthalen-1-yl) -N, N′-diphenyl- Benzidine, etc.), triphenylamines (triphenylamine, 4,4′4 ″ -tris (N, N-diphenyl-amino) -triphenylamine, 4,4′4 ″ -tris (N-3- Methylphenyl-N-phenyl-amino) -triphenylamine, 4,4′4 ″ -tris (N- (1-naphthyl) -N-phenyl-amino) -triphenylamine, etc.), triphenyldiamine Compounds having aromatic tertiary amine skeleton such as (N, N′-di- (4-methyl-phenyl) -N, N′-diphenyl-1,4-phenylenediamine), phenanthrene, pyrene, perylene, anthracene And condensed polycyclic compounds such as tetracene and pentacene (however, the condensed polycyclic compound may have a substituent), TTF (tetrathiafulvalene) s, dibenzofuran, phenothiazine, carbazole, and other organic materials. Among these, a compound having an aromatic tertiary amine as a skeleton, a condensed polycyclic compound, and an alkali metal are more preferable because the carrier concentration can be increased more effectively.

   Organic light-emitting layers such as a light-emitting layer, a hole transport layer, an electron transport layer, a hole injection layer, and an electron injection layer are prepared using a coating liquid for forming an organic light-emitting layer in which the above materials are dissolved and dispersed in a solvent Known coating methods such as spin coating method, dipping method, doctor blade method, discharge coating method, spray coating method, ink jet method, letterpress printing method, intaglio printing method, screen printing method, printing method such as microgravure coating method, etc. Wet process, known dry processes such as resistance heating vapor deposition, electron beam (EB) vapor deposition, molecular beam epitaxy (MBE), sputtering, organic vapor deposition (OVPD), etc., or laser transfer It can be formed by a method or the like. When forming the organic light emitting layer by a wet process, the coating liquid for forming the organic light emitting layer may contain additives for adjusting the physical properties of the coating liquid, such as a leveling agent and a viscosity modifier. .

   The thickness of each layer constituting the organic light emitting layer 14 is usually about 1 to 1000 nm, preferably 10 to 200 nm. If the film thickness is less than 10 nm, the properties (charge injection characteristics, transport characteristics, confinement characteristics) that are originally required cannot be obtained. In addition, pixel defects due to foreign matters such as dust may occur. Further, when the film thickness exceeds 200 nm, there is a concern that the drive voltage increases due to the resistance component of the organic light emitting layer, leading to an increase in power consumption.

   The bank (insulating layer) 15 that divides the first electrode (lower electrode) 12 into a plurality of predetermined regions (for example, pixels) is made of a material having at least light reflectivity. As the material having light reflectivity, a material having a white color tone is preferably used. Furthermore, it is also preferable to use a material having light diffusibility in addition to light reflectivity.

   In the case of only light reflectivity, the profile of the extracted light varies greatly depending on the angle of the bank side surface with respect to the substrate and the shape of the bank. Therefore, in order to obtain a desired light profile, the angle of the bank side surface with respect to the substrate and the bank There is also a need to control the shape of the material appropriately. On the other hand, if the bank has whiteness and light scattering properties in addition to light reflectivity, the direction of light reflected by the bank is widened. A natural light emission profile is easily obtained without depending on the shape of the bank.

As an example, the bank (insulating layer) 15 is made of, for example, a high-reflectance white solder resist disclosed in JP 2007-322546 A, JP 2008-211036 A, JP 2011-66267 A, or the like. Can be formed. Alternatively, it is an effective technique to disperse particles such as TiO _{2 in} a polyimide-based or acrylic-based photosensitive resin to provide functions such as light reflectivity, light scattering, and whiteness.

   The bank (insulating layer) 15 is formed in a predetermined pattern on the one surface 11 a of the light transmissive substrate 11. In order to pattern the bank 15 into a predetermined shape, a method of patterning a photosensitive resin with titanium oxide particles added using photolithography, a resin with titanium oxide particles added to the entire surface, etc. Apply a well-known manufacturing process used in semiconductor manufacturing processes, liquid crystal panel manufacturing processes, etc., such as a method of forming a photoresist pattern on it and etching the resin layer with added titanium oxide particles into a predetermined pattern can do.

   The film thickness of the bank 15 is, for example, generally in a range of 1 μm to 5 μm, but the film thickness may be appropriately selected according to the purpose. For example, a bank having a height of 100 nm to several tens of μm can be used, and the effect of the present invention can be obtained in any case.

   Before the light emitted from the organic light emitting layer 14 is reflected by the bank 15, it is not preferable that light is lost every time the total reflection is repeated. Therefore, the interval (opening diameter) between the banks 15 adjacent to each other is not so large. It is better not to be big. The intervals between adjacent banks 15 are 50 mm, 20 mm, 10 mm, 5 mm, 1 mm, 500 μm, 100 μm, 50 μm, 20 μm, and the like.

   When the bank 15 is given light scattering properties, it is preferable to disperse fine light-reflecting particles in the resin constituting the bank 15. The light reflective particles preferably have a particle size of 200 nm to 5 μm. As a result, the bank 15 can have light reflectivity and can also have light scattering properties that make the light reflection direction random.

   The bank 15 also serves to prevent leakage at the edge portion of the first electrode (lower electrode) 12. That is, when the organic light emitting layer 14 is formed on the first electrode 12, the thickness of the organic light emitting layer 14 is reduced at the end face of the first electrode 12. For this reason, a short circuit easily occurs between the first electrode 12 and the second electrode 13. By arranging the bank 15 in such a region, a short circuit can be prevented. In this case, the bank 15 is a component generally called an edge cover or an insulating layer.

   The bank 15 also prevents liquid applied to a certain pixel region of the substrate 11 from flowing to an adjacent pixel region when the organic light emitting layer 14 is formed by a wet process such as inkjet. In order to further enhance such a function, it is also preferable to perform a process for imparting liquid repellency to the bank 15.

The operation of the light emitting device having the above configuration will be described.
As shown in FIG. 1, when a voltage having a predetermined voltage value is applied between the first electrode (lower electrode) 12 and the second electrode (upper electrode) 13 of the light emitting device 10, The organic light emitting layer 14 emits light due to excitons (excitons) generated by recombination of electrons and holes injected into.

Of the light emitted from the organic light emitting layer 14 (excitation light), the light F1 emitted in the direction toward the transparent first electrode (lower electrode) 12 is transmitted through the first electrode 12 and the transparent substrate 11 to the outside. Is emitted.
Of the light (excitation light) emitted from the organic light emitting layer 14, the light F <b> 2 emitted in the direction toward the light impermeable second electrode (upper electrode) 13 is reflected by the surface of the second electrode 13. The light passes through the organic light emitting layer 14 again, passes through the first electrode 12 and the transparent substrate 11, and is emitted to the outside.

   On the other hand, of the light (excitation light) emitted from the organic light emitting layer 14, the light F <b> 3 emitted in the surface spreading direction (direction perpendicular to the stacking direction) is incident on the bank 15. The light incident on the bank 15 reflects and preferably diffuses the incident light because the bank 15 is made of a material having light reflectivity. The light F3 reflected by the bank 15 is also transmitted through the first electrode 12 and the substrate 11 and emitted to the outside.

   Thus, according to the light emitting device 10 of the present embodiment, since the bank 15 has light reflectivity, the light F3 emitted toward the bank 15 is absorbed by the bank 15 or inside the bank 15. There is no loss due to wave guiding. Then, the light F3 emitted toward the bank 15 is reflected by the bank 15 and emitted from the substrate 11 to the outside, so that the light extraction efficiency can be remarkably improved.

   That is, in contrast to the idea that the conventional light emitting device increases the light extraction efficiency by controlling the refractive index, scattering property, or shape of the organic light emitting layer, in the present invention, the light emitted from the organic light emitting layer is converted into the bank 15. It is to be confined in the region surrounded by, and not propagate in the direction of the bank 15. With such a configuration, the emission of light can be limited only to the direction in which the light is desired to be extracted, and the light can be extracted efficiently without loss. Thereby, the light extraction efficiency can be remarkably improved as compared with a conventionally known light emitting device.

   In addition, although the light reflectivity is indispensable, the bank 15 is more preferably made of a material having irregular reflectivity and scattering property instead of regular reflection. In the case of irregular reflection and scattering, the light incident on the bank 15 is reflected in a random direction, and the light extraction efficiency can be further improved compared to regular reflection.

   Further, ideally, the bank 15 is preferably covered by the bank 15 around the first electrode (lower electrode) 12 patterned in a predetermined shape. However, even if only a part of the bank 15 is covered, the effect of improving the light extraction efficiency can be obtained. However, with respect to the peripheral length of the first electrode (lower electrode) 12, for example, if a light-reflective bank is arranged only for a length of 1%, the remaining 99% of the length is Light is guided and lost in the surface spreading direction, and the effect of improving the light extraction efficiency is limited.

   Whether the light emitted from the organic light-emitting layer 14 is guided away in the surface spreading direction or escapes, or is reflected by the light-reflective bank 15 and extracted from the substrate 11 side, is the peripheral length of the first electrode 12. The ratio of the length in which the bank 15 is arranged correlates with the length. For example, assuming that the light extraction efficiency without using a light reflective bank is 25%, the loss is 75%. If the ratio of the length in which the bank 15 is arranged to the peripheral length of the first electrode 12 is 10%, approximately 7.5% of light may be extracted on the basis of the total light. The extraction efficiency is 32.5%, which is an improvement of about 30% compared to the extraction efficiency of 25% when the light-reflective bank 15 is not formed.

   However, if the ratio of the length in which the bank 15 is arranged to the peripheral length of the first electrode 12 is 1%, the light extraction is improved only by 0.75% at the maximum, and the total light extraction is performed. The efficiency is only 25.75%. This is only a 3% improvement over the light extraction efficiency of 25% when the light-reflective bank 15 is not provided, and the obtained effect is too small.

   From such a viewpoint, the ratio of the length in which the bank 15 is disposed to the peripheral length of the first electrode (lower electrode) 12 is ideally 100%, but is approximately 5% or more. Accordingly, a corresponding effect of improving the light extraction efficiency can be obtained.

When the ratio of the length in which the bank 15 is arranged to the peripheral length of the first electrode 12 is 5%, the maximum amount of light extracted by the light reflective bank 15 is 3.75% (75% × 5 %) For a total of 27.75%. This is a 15% improvement over the light extraction efficiency of 25% when the light-reflective bank 15 is not provided, and can be said to be a meaningful improvement.
However, since there is substantially a light loss in other constituent parts and a loss due to wave guide in the substrate 11, it is preferable that the light reflective property be compared with the peripheral length of the first electrode 12. The ratio of the length in which the bank 15 is arranged is preferably 50% or more, and particularly preferably 100%.

   The ratio of the length in which the bank 15 is arranged with respect to the peripheral length of the first electrode 12 can be determined by, for example, the shape when the bank 15 is patterned. Considering a general case, it is not difficult to cover the entire periphery of the first electrode 12 with the bank 15, and it is formed by suppressing leakage between the second electrode 13 and the first electrode 12 and by a wet process. Considering the viewpoint of preventing inflow into adjacent pixels, it is preferable to cover the entire periphery of the first electrode (lower electrode) 12 with the light reflective bank 15.

   Moreover, it is preferable to seal the periphery of the light emitting device 10 by an appropriate method in order to ensure reliability. As a sealing method, a known method or the like can be used. For example, a method using a can seal and a desiccant, a method using a cap glass and a desiccant, a glass frit seal, a method of pasting together a film with suppressed moisture permeability and glass, and the like.

(Light Emitting Device: Second Embodiment)
FIG. 2 is a schematic cross-sectional view showing a light emitting device according to the second embodiment.
The light-emitting device 20 includes a light-transmitting substrate 21, a first electrode (lower electrode) 22, a second electrode (upper electrode) 23, a first electrode 22 and a first electrode, which are sequentially stacked on one surface 21a of the substrate 21. And an organic light emitting layer 24 formed between the two electrodes 23. A light-reflective bank (insulating layer) 25 that divides the first electrode 22 into a plurality of predetermined regions is formed on the one surface 21a of the substrate 21.

   In this embodiment, the organic light emitting layer 24 is formed, for example, divided for each pixel. That is, in the first embodiment, the organic light emitting layer 14 is formed as a series of layers over the bank 15 (see FIG. 1), but in the second embodiment, the organic light emitting layer 24 is formed above the bank 25. It is divided into a plurality of sections separated by (second electrode side). Thereby, light propagating through the organic light emitting layer 24 and propagating in the surface spreading direction can be blocked, and the light extraction efficiency can be further improved.

(Light emitting device: third embodiment)
FIG. 3 is a schematic sectional view showing a light emitting device according to the third embodiment.
The light-emitting device 30 includes a light-transmitting substrate 31, a first electrode (lower electrode) 32, a second electrode (upper electrode) 33, a first electrode 32, and a first electrode laminated on one surface 31a of the substrate 31 in this order. An organic light emitting layer 34 formed between the two electrodes 33. In addition, a light reflective bank (insulating layer) 35 that divides the first electrode 32 and the organic light emitting layer 34 into a plurality of predetermined regions is formed on the one surface 31 a of the substrate 31.

   In this embodiment, the organic light emitting layer 34 is partitioned by the bank 35 for each pixel, for example. That is, in the first embodiment, the organic light emitting layer 14 is formed as a series of layers over the bank 15 (see FIG. 1). However, in the third embodiment, the organic light emitting layer 24 includes a plurality of banks 35. It is divided into. Thereby, the light propagating through the organic light emitting layer 24 and blocking the light propagating in the surface spreading direction is blocked, and the light emitted from the side cross section (thickness direction cross section) of the organic light emitting layer 24 is also reflected in the light reflective bank. Therefore, the light extraction efficiency can be further improved.

   In the second embodiment and the third embodiment, as a method of forming the organic light emitting layers 24 and 34 by limiting the formation region within a predetermined range, for example, a mask vapor deposition method, an inkjet method, printing, or the like is used. Coating using a wet method, a method using a laser such as LITI (Laser Induced Thermal Imaging), LIPS (laser Induced Pattern Wise Sublimation), or a method such as a photobleaching method may be used as appropriate.

(Light-emitting device: Fourth embodiment)
FIG. 4 is a schematic sectional view showing a light emitting device according to the fourth embodiment.
The light-emitting device 40 includes a light-transmitting substrate 41, a low refractive index layer 46, a first electrode (lower electrode) 42, a second electrode (upper electrode) 43, and the like. An organic light emitting layer 44 formed between the first electrode 42 and the second electrode 43. In addition, a light reflective bank (insulating layer) 45 that divides the first electrode 42 into a plurality of predetermined regions is formed on one surface of the low refractive index layer 46.

   In this embodiment, a low refractive index layer 46 having a refractive index lower than that of the substrate 41 is formed between the substrate 41 and the first electrode (lower electrode) 42. The refractive index of the low refractive index layer is preferably lower than the refractive index of the substrate, and ideally 1.0 is most preferable, which is the same as the refractive index of air.

   By forming such a low refractive index layer 46, the light extraction efficiency can be further improved. That is, assuming that the refractive index of air (outside air) is 1.0 and the refractive index of the substrate 41 is 1.5, if the low refractive index layer 46 is not provided, the light emitted from the organic light emitting layer is air from the substrate. Although the light travels straight to the (outside air) interface, light having an angle greater than 42 ° from the normal is totally reflected due to a difference in refractive index at the interface between the substrate and air (outside air).

   On the other hand, as shown in FIG. 4, when the low refractive index layer 46 having a refractive index of 1.2 is provided, for example, at the interface between the substrate 41 and air (outside air), the angle from the normal is 53 °. Although large light is totally reflected, the possibility that the reflected light is reflected by the light-reflective bank 45 and taken out to the outside increases. Also in the embodiment shown in FIG. 4, light having an angle from the normal of 42 ° to 53 ° cannot be totally reflected at the interface between the substrate 41 and air (outside air), but the light emitted from the organic light emitting layer 44 is not reflected. In terms of angle, only the light of 42 ° to 53 ° cannot be extracted, and the effect of improving the light extraction efficiency by forming the low refractive index layer 46 is great.

   The thickness in the configuration shown in FIG. 4 is about 100 nm to several tens of μm from the organic light emitting layer 44 to the interface between the first electrode 42 and the low refractive index layer 46, and the first electrode 42 and the low refractive index are low. The distance from the interface with the layer 46 to the interface between the substrate 41 and air (outside air) is 0.5 mm to 0.7 mm.

   If only the low-refractive index layer 46 is formed without providing the light-reflective bank, the light bounced off at the interface between the first electrode 42 and the low-refractive index layer 46 repeats regular reflection in the surface spreading direction. The light extraction efficiency will not improve so much. Therefore, by using the light-reflective bank 45 and the low refractive index layer 46 in combination, a significant improvement in the light extraction efficiency can be obtained.

(Light-emitting device: fifth embodiment)
FIG. 5 is a schematic sectional view showing a light emitting device according to the fifth embodiment.
The light-emitting device 50 includes a light-transmitting substrate 51, a low refractive index layer 56, a first electrode (lower electrode) 52, a second electrode (upper electrode) 53, which are sequentially stacked on one surface 51a of the substrate 51, And an organic light emitting layer 54 formed between the first electrode 52 and the second electrode 53. A light reflective bank (insulating layer) 55 is formed on one surface of the low refractive index layer 56 to partition the first electrode 52 and the organic light emitting layer 54 into a plurality of predetermined regions.

   In this embodiment, the organic light emitting layer 54 is partitioned by the bank 55, for example, for each pixel. That is, in the fourth embodiment, the organic light emitting layer 44 is formed as a series of layers over the bank 45 (see FIG. 4), but in the fifth embodiment, the organic light emitting layer 54 includes a plurality of banks 55. It is divided into. Thereby, the light propagating through the organic light emitting layer 54 and blocking the light propagating in the surface spreading direction is blocked, and the light emitted from the side cross section (thickness direction cross section) of the organic light emitting layer 54 is also a light reflective bank. The light extraction efficiency can be further improved along with the formation of the low refractive index layer 56.

(Example of bank shape)
The shape of the bank can be various. FIG. 8 is a cross-sectional view showing an example of the shape of a bank.
In FIG. 8A, the bank 103 that partitions the first electrode (lower electrode) 102 formed on the substrate 101 is formed to have a trapezoidal shape with a narrow upper portion.
In FIG. 8B, the bank 104 that divides the first electrode (lower electrode) 102 formed on the substrate 101 is formed to have a trapezoidal shape with the upper part widened.
In FIG. 8C, the bank 105 that partitions the first electrode (lower electrode) 102 formed on the substrate 101 is formed so that the upper part is semicircular or semielliptical.
In FIG. 8D, the bank 106 that partitions the first electrode (lower electrode) 102 formed on the substrate 101 is formed so that the upper part is a semicircular shape and the top part is a flat surface.
In FIG. 8E, the bank 107 that partitions the first electrode (lower electrode) 102 formed on the substrate 101 is formed so that the upper part is a triangle.

   Among these bank shapes, as shown in FIG. 8A, FIG. 8C, FIG. 8D, and FIG. There is an effect that light is more easily emitted. Since such an effect also affects the light emission profile, it contributes to a wide viewing angle when applied to a display device. From the viewpoint of this wide viewing angle, the shape of the bank 107 shown in FIG. 8E is most preferable. On the other hand, in order to suppress the layer formed on the bank from being cut at the edge portion, the shape shown in FIG. A shape in which the banks 105 and 106 are rounded as shown in FIG. 8C and FIG.

   On the other hand, although this technique is often used in passive drive organic EL display devices, when the reverse-tapered bank 104 as shown in FIG. 8B is formed, thereby forming the second electrode (upper electrode) over the entire surface. In addition, the second electrode (upper electrode) can be formed in a stripe shape by causing step breakage at the edge portion of the bank 104. Furthermore, the structure of the bank 104 in FIG. 8B is also effective in narrowing the viewing angle and playing the role of a privacy filter in the organic EL display device mainly intended for private use.

(Example of bank structure)
In each of the above-described embodiments, an example in which the bank itself is formed of a light-reflective resin such as a white resin has been described. However, the structure of the bank is not limited to this.
FIG. 9 is a sectional view showing an example of a structure for imparting light reflectivity to the bank.
In FIG. 9A, the bank 113 that partitions the first electrode (lower electrode) 112 formed on the substrate 111 includes a resin layer 113a and a light-reflective metal layer 113b.
The resin layer 113a is transparent, light reflective, light scattering, white, or colored. The resin layer 113a needs to be insulative when a different voltage is applied to each first electrode. For example, when the first electrode is formed for each pixel in a display application, or when an organic layer having a different emission color is arranged for each first electrode in a lighting application to provide a dimming function, etc. It is.

   On the other hand, the resin layer 113a does not need to be insulative when the same voltage may be applied to all the first electrodes, as in the case of a normal lighting application that only requires uniform illumination. When the resin layer 113a is colored, especially in the case of black, it has the effect of reducing external light reflection, and is particularly effective in display applications. When the resin layer 113a is colored red, green, blue or the like, this color can be seen from the outside. This is preferable from the viewpoint of design in the case of lighting applications. When the resin layer 113a is light-reflective, light-scattering, white, etc., light that propagates through the substrate 111 or the organic layer and escapes in the lateral direction strikes the resin layer 113a and changes its direction. There is an effect of increasing the probability of being taken out of the.

   In FIG. 9B, the bank 114 that partitions the first electrode (lower electrode) 112 formed on the substrate 111 is made of a reflective metal or resin layer. The bank 114 is disposed between the first electrodes (lower electrodes) 112 so as to be separated from the first electrode 112. In the display application, when the first electrode is formed for each pixel, or in the illumination application, an organic layer having a different light emission color is arranged for each first electrode to give a dimming action, etc. Even when a different voltage is applied to each first electrode, even if the bank 114 is a reflective metal, this structure ensures insulation. When the bank 114 is a resin layer, the resin layer is light reflective, light scattering, or white. As described in other embodiments, the resin layer acts to increase the probability of reflecting light propagating in the lateral direction and extracting it in the front direction.

  In FIG. 9C, the bank 115 that partitions the first electrode (lower electrode) 112 formed on the substrate 111 is composed of a reflective metal body 115a and a resin layer 115b covering the same. The resin layer 115b is transparent, light reflective, light scattering, or white. When the resin layer 115b is transparent, the light propagating in the lateral direction in the device is reflected by the reflective metal body 115a and the light traveling direction is changed, so that the light extraction efficiency is improved. In addition, when the resin layer 115b is light-reflective, light-scattering, or white, the light propagating in the device in the lateral direction is reflected or scattered by the resin layer 115b, and also light that is not reflected or scattered by the resin layer 115b Since the light is reflected by the reflective metal body 115a, the light extraction efficiency is improved.

  In this embodiment, the upper portion of the reflective metal body 115a may be covered with the resin layer 115b, but considering the possibility of light propagating from this region, the thickness of the upper portion of the resin layer 115b is reduced. It is preferable to form. Furthermore, the shape which does not form resin in this part is also preferable. When the first electrode is formed for each pixel in the display application, or the resin layer 115b has a light control function by arranging an organic layer having a different emission color for each first electrode in the illumination application. In the case where a different voltage is applied to each first electrode, it is necessary to be insulative. On the other hand, the resin layer 115b does not need to be insulative when it is sufficient to apply the same voltage to all the first electrodes, as in the case of normal lighting applications that only require uniform illumination.

  In FIG. 9D, the bank 116 that partitions the first electrode (lower electrode) 112 formed on the substrate 111 includes a reflective metal body 116a, a resin layer 116b that covers the reflective metal body 116a, and an upper reflective layer 116c. Has been. The resin layer 116b is transparent, light reflective, light scattering, or white. When the resin layer 116b is transparent, the light propagating in the lateral direction in the device is reflected by the reflective metal body 116a and the upper reflective layer 116c, and the light traveling direction is changed, so that the light extraction efficiency is improved. In addition, when the resin layer 116b is light-reflective, light-scattering, or white, light propagating in the lateral direction in the device is reflected or scattered by the resin layer 116b, and light that is not reflected or scattered by the resin layer 116b is also present. Since the light is reflected by the reflective metal body 116a and the upper reflective layer 116c, the light extraction efficiency is improved.

  In the display application, the resin layer 116b has a dimming function when the first electrode is formed for each pixel, or in the illumination application, an organic layer having a different emission color is arranged for each first electrode. In the case where a different voltage is applied to each first electrode, it is necessary to be insulative. On the other hand, the resin layer 116b does not need to be insulative when the same voltage may be applied to all the first electrodes as in the case of normal lighting applications that only require uniform illumination.

  In FIG. 9 (e), the bank 117 defining the first electrode (lower electrode) 112 formed on the substrate 111 is formed from a reflective metal layer or a resin layer covering at least the side surface of the first electrode (lower electrode) 112. It is configured. And this bank 117 is arrange | positioned so that the edge of a 1st electrode (lower electrode) may be covered, and the banks 117 which cover the different 1st electrode 112 are not contacting. In the display application, when the first electrode is formed for each pixel, or in the illumination application, an organic layer having a different light emission color is arranged for each first electrode to give a dimming action, etc. Even when a different voltage is applied to each first electrode, even if the bank 117 is a reflective metal, this structure ensures insulation. When the bank 117 is a resin layer, the resin layer is light reflective, light scattering, or white. As described in the other embodiments, the resin layer acts to increase the probability that the light generally reflected in the lateral direction is reflected and extracted in the front direction.

  In FIG. 9F, the bank 118 that partitions the first electrode (lower electrode) 112 formed on the substrate 111 includes a resin body 118a and a reflective metal layer 118b that covers the resin body 118a. The resin layer 118a is transparent, light reflective, light scattering, or white. When the resin layer 118a is transparent, the light propagating in the lateral direction in the device is reflected by the reflective metal body 118b and the light traveling direction is changed, so that the light extraction efficiency is improved. When the resin layer 118a is light-reflective, light-scattering, or white, the light propagating laterally in the device is reflected or scattered by the resin layer 118a, and light that is not reflected or scattered by the resin layer 118a is also reflective. Since it is reflected by the metal body 118b, the light extraction efficiency is improved.

  When the first electrode is formed for each pixel in the display application, or the resin layer 118a has a dimming effect by arranging an organic layer having a different emission color for each first electrode in the illumination application. In the case where a different voltage is applied to each first electrode, it is necessary to be insulative. On the other hand, the resin layer 118a does not need to be insulative when the same voltage is applied to all the first electrodes, as in the case of normal lighting applications that only require uniform illumination.

9, the first electrode (lower electrode) 112 is formed so as to be in direct contact with the substrate 111. However, the first electrode 112 and the substrate 111 are disposed between the first electrode 112 and the substrate 111. It is also preferable to further form the low refractive index layer shown in the fourth and fifth embodiments.

(Display device: sixth embodiment)
FIG. 6 is a schematic sectional view showing a display device according to the sixth embodiment.
In this embodiment, an organic EL display device in which a light emitting device is driven in an active matrix is shown. An organic EL display device (display device) 60 includes a light transmissive substrate 61, a first electrode (lower electrode) 62, a second electrode (upper electrode) 63, and the first electrode 62 and the second electrode 63. A light-emitting device 67 is provided that includes the formed organic light-emitting layer 64 and a light-reflective bank (insulating layer) 65 that partitions the first electrode 62 into a plurality of predetermined regions.

   An active matrix drive element (drive unit) 70 that is an example of a drive unit is formed between the substrate 61 and the first electrode (lower electrode) 62. A gate electrode 70 a and a gate oxide film 68 are formed on the substrate 61. An active layer 70d, a source electrode 70b and a drain electrode 70c are formed on the gate oxide film 68, and an interlayer insulating film 69 is further formed. A contact hole is provided in the interlayer insulating film 69, and the drain electrode 70c and the first electrode 62 are electrically joined. The active matrix driving element 70 includes a gate electrode 70a, a gate oxide film 68, a source electrode 70b, a drain electrode 70c, an active layer 70d, and the like.

An active matrix driving element (driving unit) 70 that is an example of a driving unit that controls light emission of the light emitting device 67 functions as a switching unit and a driving unit. Such an active matrix driving element 70 can be formed using a known material, structure and forming method.
Examples of the material of the active layer 70d include inorganic semiconductor materials such as amorphous silicon (amorphous silicon), polycrystalline silicon (polysilicon), microcrystalline silicon, cadmium selenide, zinc oxide, indium oxide-gallium oxide-oxide. An oxide semiconductor material such as zinc, or an organic semiconductor material such as a polythiophene derivative, a thiophene oligomer, a poly (p-ferylene vinylene) derivative, naphthacene, or pentacene can be given. Examples of the TFT structure include a staggered type, an inverted staggered type, a top gate type, and a coplanar type.

As a method for forming the active layer 70d, (1) a method of ion-doping impurities into amorphous silicon formed by a plasma induced chemical vapor deposition (PECVD) method, and (2) a reduced pressure chemistry using silane (SiH ₄ ) gas. Amorphous silicon is formed by vapor phase epitaxy (LPCVD), and amorphous silicon is crystallized by solid phase epitaxy to obtain polysilicon, followed by ion doping by ion implantation, (3) Si ₂ H ₆ gas Amorphous silicon is formed by LPCVD method or PECVD method using SiH ₄ gas, annealed by laser such as excimer laser, etc., and amorphous silicon is crystallized to obtain polysilicon, followed by ion doping (low temperature process) ), (4) LPCVD method or PECVD method Ri to form a polysilicon layer, a gate insulating film formed by thermal oxidation at 1000 ° C. or higher, thereon to form a gate electrode of the n ⁺ polysilicon, then, a method of performing ion doping (high temperature process) (5) A method of forming an organic semiconductor material by an inkjet method or the like, and (6) a method of obtaining a single crystal film of the organic semiconductor material.

The gate insulating film 68 can be formed using a known material. Examples thereof include SiO ₂ formed by PECVD, LPCVD, etc., or SiO ₂ obtained by thermally oxidizing a polysilicon film. The signal electrode line, the scanning electrode line, the common electrode line, the first drive electrode, and the second drive electrode of the TFT can be formed using a known material, for example, tantalum (Ta), aluminum (Al). , Copper (Cu), and the like.

The interlayer insulating film 69 can be formed using a known material, for example, silicon oxide (SiO ₂ ), silicon nitride (SiN or Si ₂ N ₄ ), tantalum oxide (TaO or Ta ₂ O). ₅ )) or an organic material such as an acrylic resin or a resist material. Examples of the formation method include dry processes such as chemical vapor deposition (CVD) and vacuum deposition, and wet processes such as spin coating. Moreover, it can also pattern by the photolithographic method etc. as needed.

   When the active matrix driving element 70 is formed on the substrate 61, irregularities are formed on the surface thereof, and the irregularities of the light emitting device 67 (for example, pixel electrode defects, organic EL layer defects, counter electrodes, etc.) Disconnection, short circuit between the pixel electrode and the counter electrode, reduction in breakdown voltage, etc.). In order to prevent these defects, a planarizing film may be further provided on the interlayer insulating film 69.

   Such a planarization film can be formed using a known material, and examples thereof include inorganic materials such as silicon oxide, silicon nitride, and tantalum oxide, and organic materials such as polyimide, acrylic resin, and resist material. Examples of the method for forming the planarizing film include dry processes such as CVD and vacuum deposition, and wet processes such as spin coating, but the present invention is not limited to these materials and forming methods. Further, the planarization film may have a single layer structure or a multilayer structure.

   Further, a color filter, a color conversion film, and the like may be further combined with the organic EL display device (display device) 60 described above. When combined with a color filter, the emission color is usually white. When combined with a color conversion film, the emission color is usually blue.

(Display device: seventh embodiment)
FIG. 7 is a schematic sectional view showing a display device according to the seventh embodiment.
The organic EL display device (display device) 80 includes a light-transmissive substrate 81, a low refractive index layer 86, a first electrode (lower electrode) 82, a second electrode (upper electrode) 83, and the first electrode 82 and the first electrode 82. The light emitting device 87 includes an organic light emitting layer 84 formed between the two electrodes 83 and a light reflective bank (insulating layer) 85 that partitions the first electrode 82 into a plurality of predetermined regions.

   An active matrix drive element (drive unit) 90 which is an example of a drive unit is formed between the substrate 81 and the first electrode (lower electrode) 82. A gate electrode 90 a and a gate oxide film 88 are formed on the substrate 81. On the gate oxide film 88, an active layer 90d, a source electrode 90b, a drain electrode 90c are formed, and an interlayer insulating film 89 is further formed. A contact hole is provided in the interlayer insulating film 89, and the drain electrode 90c and the first electrode 82 are electrically joined. The active matrix driving element 90 includes a gate electrode 90a, a gate oxide film 88, a source electrode 90b, a drain electrode 90c, an active layer 90d, and the like.

In this embodiment, a low refractive index layer 86 having a refractive index lower than that of the substrate 81 is formed between the substrate 81 and the first electrode (lower electrode) 82. The low refractive index layer 86 is such that, for example, the critical angle of incident light incident from the organic light emitting layer 84 toward the low refractive index material layer 86 is smaller than the critical angle of outgoing light emitted from the substrate 81 to the outside. It preferably has a refractive index.
By forming such a low refractive index layer 86, the light extraction efficiency can be further improved.

(Light Emitting Device: Eighth Embodiment)
In order to increase the conductivity of the first electrode (lower electrode), it is also preferable to form a light-reflective bank in a light-emitting device that further includes an auxiliary electrode.
FIG. 10 is a schematic cross-sectional view showing the light emitting device according to the eighth embodiment. 10A is a plan view of the light emitting device as viewed from above, and FIG. 10B is a cross-sectional view taken along the line AA in FIG. 10A.

   In the light emitting device 200 of this embodiment, an auxiliary wiring 209 is formed on a light transmissive substrate 201 such as glass. One or a plurality of auxiliary wirings 209 may be arranged. For the auxiliary wiring 209, a metal material having a low electric resistance value such as Al or Ag is usually used. When a plurality of auxiliary wirings 209 are arranged, for example, they can be arranged in a stripe shape or a lattice shape.

   The auxiliary wiring 209 is covered with the first electrode (lower electrode) 202. For the first electrode (lower electrode) 202, for example, a transparent electrode material such as ITO or IZO is used, and the film thickness is, for example, about 100 nm to 300 nm. In order to form the first electrode 202 in a predetermined shape, a patterning method using photolithography or the like, or mask deposition can be used.

   A light-reflective bank 205 is formed between adjacent first electrodes (lower electrodes) 202. Even if the bank 205 covers only a part of the periphery of the first electrode (lower electrode) 202, the effect of improving the light extraction efficiency can be obtained. However, enclosing the entire periphery is most effective for improving the light extraction efficiency. High and preferable. In FIG. 10, the opening area of the light-reflective bank 205 is drawn in a square shape, but a rectangular shape, a circular shape, or other shapes are possible. The opening size of the bank 205 is not limited, and various sizes such as an opening diameter of 0.5 mm, 1 mm, 5 mm, 10 mm, 50 mm, and 100 mm can be selected.

   An organic light emitting layer 204 is formed on the first electrode (lower electrode) 202. As the organic light emitting layer 204, for example, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, a laminated film of an electron injection layer, or the like can be used. A second electrode (upper electrode) 203 is formed on the organic light emitting layer 204. For example, LiF / Al may be used as the cathode of the second electrode (upper electrode) 203.

Furthermore, although not shown in FIG. 10, in order to protect the light emitting device 200 from corrosion and alteration due to moisture and oxygen in the atmosphere, it is preferable to seal using a counter substrate or the like.
If there is a concern that the second electrode (upper electrode) 203 is disconnected due to the bank 205 having an inversely tapered shape or the like, FIGS. 11 (a) and 11 (b). As shown in FIG. 2, it is preferable to form a portion having no step.

     Hereinafter, modified examples of the eighth embodiment shown in FIG. 10 are shown in FIGS. In these embodiments, the same members as those in FIG. 10 are denoted by the same reference numerals, and detailed description thereof is omitted. 14 to 20, (a) is a plan view when the light emitting device is viewed from above, and (b) is a cross-sectional view taken along line AA of (a).

     The auxiliary wiring 209 may be arranged in the light emitting area as shown in FIG. 10, but when the auxiliary wiring is formed by an opaque electrode, the auxiliary wiring blocks the emitted light. Not necessarily preferred. On the other hand, as shown in FIG. 14, it is preferable to arrange the auxiliary wiring outside the light emitting area because the emitted light can be extracted more smoothly. In the embodiment shown in FIG. 10, the organic light emitting layer 204 is formed in the bank 205. However, as in the light emitting device 210 of the embodiment shown in FIG. Also good. From the viewpoint of productivity, this form formed on the entire surface of the substrate is efficient.

In FIG. 14, of the light (excitation light) emitted from the organic light emitting layer 204, the light emitted in the direction toward the transparent first electrode (lower electrode) 202 is transmitted through the first electrode 202 to the substrate 201. Incident.
Of the light emitted from the organic light emitting layer 204 (excitation light), the light emitted in the direction toward the light-impermeable second electrode (upper electrode) 203 is reflected by the surface of the second electrode 203, The light passes through the organic light emitting layer 204 again, passes through the first electrode 202, and enters the substrate 201.

     On the other hand, of the light (excitation light) emitted from the organic light emitting layer 204, the light emitted in the surface spreading direction (direction perpendicular to the stacking direction) enters the bank 205. The light incident on the bank 205 reflects and preferably diffuses the incident light because the bank 205 is made of a material having light reflectivity. The light reflected by the bank 205 also passes through the first electrode 202 and enters the substrate 201.

     The light incident on the substrate 201 travels to the interface between the substrate 201 and air. Here, since there is a difference in refractive index between the substrate 201 and air, a part of the light is emitted to the outside, but light having an angle shallower than a certain angle defined by the difference in refractive index between the substrate 201 and air is reflected on the substrate 201. Reflected at the air interface. A part of the reflected light hits the bank 205 is reflected, preferably scattered, and travels again toward the interface between the substrate 201 and the air. At this time, since the angle is changed by reflection at the bank 205, preferably by scattering, light having an angle that is not reflected at the interface between the substrate 201 and the air is extracted to the outside. By repeating such a process, a lot of light is finally extracted to the outside, and the light extraction efficiency is increased.

     As described above, the light extraction efficiency is improved by the bank 205 having the light reflectivity or the light scattering property. Without the bank 205, the light emitted in the surface spreading direction (direction perpendicular to the stacking direction) is not extracted outside, and the light reflected at the interface between the substrate 201 and the air also passes through the element. It only propagates in the surface spreading direction (perpendicular to the stacking direction) and is not taken out.

     In the embodiment shown in FIG. 14, the auxiliary wiring 209 is covered by the first electrode (lower electrode) 202, but other than that, for example, as in the light emitting device 220 of the embodiment shown in FIG. The auxiliary wiring 209 may be formed so that a part of the auxiliary wiring 209 comes into contact.

   In the embodiment shown in FIG. 10, the auxiliary wiring 209 is covered with the first electrode (lower electrode) 202. However, like the light emitting device 230 of the embodiment shown in FIG. An auxiliary wiring 209 may be formed thereon.

   In the case of the embodiments shown in FIGS. 10, 14 and 15, the manufacturing process usually includes (1) formation of an auxiliary electrode film, (2) patterning of the auxiliary electrode film, and (3) lower electrode film. And (4) patterning of the lower electrode film. On the other hand, in the embodiment shown in FIG. 16, (1) the lower electrode film and the auxiliary electrode film are continuously formed, then (2) the patterning of the auxiliary electrode film, and (3) the pattern of the lower electrode film. It is possible to manufacture in three steps by performing the annealing, and there is a merit in the manufacturing process.

   In the embodiment shown in FIG. 10, the first electrode (lower electrode) 202 is patterned, and the bank 205 is formed so as to cover the periphery of the first electrode (lower electrode) 202. However, the light emitting device 240 of the embodiment shown in FIG. Thus, the 1st electrode (lower electrode) 202 does not need to be patterned. In the light emitting device 240 shown in FIG. 17, the auxiliary wiring 209 is drawn for each region, but the auxiliary wiring 209 may be thinned out as appropriate.

     In the embodiment shown in FIG. 17, the auxiliary wiring 209 is covered with the first electrode (lower electrode) 202. However, like the light emitting device 250 of the embodiment shown in FIG. Auxiliary wiring 209 may be formed. In the embodiment shown in FIG. 18, the auxiliary wiring 209 is formed for each region. However, the auxiliary wiring 209 may be thinned out as appropriate.

     In the case of the embodiment shown in FIGS. 10, 14 and 15, the manufacturing process includes (1) formation of an auxiliary electrode film, (2) patterning of the auxiliary electrode film, and (3) film formation of the lower electrode film. (4) Four steps of patterning the lower electrode film are taken. On the other hand, as a manufacturing process of the light emitting device 250 of the embodiment shown in FIG. 18, (1) a lower electrode film and an auxiliary electrode film are continuously formed, and then (2) auxiliary electrode film patterning, (3) By performing the lower electrode film patterning, it can be manufactured in three steps, which is advantageous in the manufacturing process.

     Note that in the case where the second electrode (upper electrode) 203 is broken due to the shape of the bank 205 being an inversely tapered shape or the like, FIG. 11A and FIG. As a modified example, as shown in FIG. 19, a light emitting device 260 in which a portion without a step is formed and the first electrode (lower electrode) 202 is not patterned may be used.

     In the embodiment shown in FIGS. 11 and 19, the portion where the bank 205 is not formed is drawn so as to be in a straight line, but this position may be another position. If it is on a straight line, the light traveling in this direction does not hit the bank, which may cause light that cannot be extracted. On the other hand, for example, it is also preferable to form the portion where the bank 205 is not formed so as not to be in a straight line like the light emitting device 270 of the embodiment shown in FIG. In this way, light that is lost without hitting the bank 205 can be eliminated, and the second electrode (upper electrode) 203 can be prevented from being disconnected.

In the embodiments shown in FIG. 10, FIG. 11, and FIG. 14 to FIG. 20, the auxiliary wiring 209 is arranged in a stripe shape. You may form in a grid | lattice form. In the embodiments shown in FIGS. 14 to 20, the auxiliary wiring 209 is arranged in a stripe shape on one side of each region, but may be arranged on both sides of each region.
The light-emitting devices of the embodiments shown in FIGS. 10, 11, and 14 to 20 described above are particularly suitable when applied to lighting applications as shown in FIGS. 13 (A) and 13 (B).

   The bank formation patterns shown in these embodiments can take various forms. Although typical examples of bank formation patterns are listed in FIGS. 21A to 21I, the shape of the bank is not limited to these embodiments.

FIG. 21A shows each region formed in a square shape.
FIG. 21B shows each region formed in a circular shape. When each region is circular, there is an advantage that the profile of light reflected by the bank is equal in each direction. In addition, when the organic layer is formed by a coating method, there are corners such as a square. Although there may be a problem that the liquid is difficult to spread only in that portion, the liquid can be spread uniformly because there is no corner in the case of a circular shape. In FIG. 21B, each region is drawn in a circle, but may be formed in an ellipse or a shape in which corners of a rectangle are rounded.

FIG. 21 (c) shows a hexagonal arrangement of the areas. By adopting the hexagonal arrangement, the ratio of the light emitting areas can be increased as compared with the embodiment of FIG.
FIG. 21D shows a hexagonal arrangement of hexagonal regions.
FIG. 21E shows an area where a bank is not formed in a part of each area. By doing so, it is possible to prevent the second electrode from stepping over the bank, and to improve the yield and reliability.
FIG. 21 (f) shows an example in which the positions of regions where no bank is formed in a part of each region are not aligned.

   In the case of the embodiment shown in FIG. 9 (e), in the region where no bank is formed, the light guided in the lateral direction is not reflected and scattered to the edge of the device, resulting in a loss. On the other hand, in FIG. 9F, in the region where the bank is not formed, light travels from the region guided in the lateral direction to the next region, and the light hits the bank in the next region. Therefore, loss of light can be suppressed. 9 (g), FIG. 9 (h), and FIG. 9 (i) are formed in a part of each region in the configuration of FIG. 9 (d), FIG. 9 (b), and FIG. 9 (c). An area that is not to be used is arranged.

(Application examples of light emitting devices)
As examples of application of the light-emitting device, a mobile phone illustrated in FIG. 12A, an organic EL television illustrated in FIG.
A cellular phone 1000 illustrated in FIG. 12A includes a main body 1001, a display portion 1002, a sound input portion 1003, a sound output portion 1004, an antenna 1005, an operation switch 1006, and the like. The display portion 1002 includes the functions described in the above embodiments. A light emitting device is used.

A television receiver 1100 illustrated in FIG. 12B includes a main body cabinet 1101, a display portion 1102, a speaker 1103, a stand 1104, and the like, and the light-emitting devices of the above embodiments are used for the display portion 1102.
In these cellular phones and organic EL televisions, since the light emitting device of each of the above embodiments is used, the luminance is high and the display quality is excellent.

   As an application example of the light-emitting device, for example, the light-emitting device can be applied to a ceiling light (illumination device) illustrated in FIG. A ceiling light 1400 illustrated in FIG. 13A includes a lighting unit 1401, a hanging tool 1402, a power cord 1403, and the like. And the light emitting device of each said embodiment can be applied suitably as the illumination part 1401. FIG. By applying the light-emitting device according to an embodiment of the present invention to the illumination unit 1401 of the ceiling light 1400, it is possible to obtain bright and free-colored illumination light with low power consumption, and high lighting performance. Can be realized. In addition, it is possible to realize a lighting fixture capable of emitting surface light with high color purity with uniform illuminance.

   As an application example of the light-emitting device, for example, the light-emitting device can be applied to a lighting stand illustrated in FIG. A lighting stand 1500 illustrated in FIG. 13B includes a lighting portion 1501, a stand 1502, a power switch 1503, a power cord 1504, and the like. And the light emitting device of each said embodiment can be applied suitably as the illumination part 1501. FIG. By applying the light-emitting device according to an embodiment of the present invention to the lighting unit 1501 of the lighting stand 1500, it is possible to obtain bright and free-colored illumination light with low power consumption, and to have high light performance. Can be realized. In addition, it is possible to realize a lighting fixture capable of emitting surface light with high color purity with uniform illuminance.

   The present invention can be used for a light emitting element, and more specifically, can be used for a display device, a display system, a lighting device, a lighting system, and the like.

  DESCRIPTION OF SYMBOLS 10 ... Light emitting device, 11 ... Board | substrate, 12 ... 1st electrode (lower electrode), 13 ... 2nd electrode (upper electrode), 14 ... Organic light emitting layer, 15 ... Bank.

Claims (10)

A light-emitting device having a first electrode and a second electrode laminated in order on one surface of a light-transmitting substrate, and an organic light-emitting layer formed between the first electrode and the second electrode,
A bank for partitioning at least the first electrode into a plurality of predetermined areas;
The bank is made of a material having light reflectivity.    The light emitting device according to claim 1, wherein the second electrode is made of a light-shielding material.    The light emitting device according to claim 1, wherein the first electrode is made of a light transmissive material.    The light-emitting device according to claim 1, wherein the bank is made of a white material.    5. The light emitting device according to claim 1, wherein the bank is made of a material having a light diffusing property in addition to the light reflecting property.    6. The light-emitting device according to claim 1, wherein the bank is formed by dispersing fine light-reflecting particles in a resin.    The light-emitting device according to claim 6, wherein the light-reflecting particles have a particle size of 200 nm to 5 μm.    8. The light emitting device according to claim 1, further comprising a low refractive index layer having a refractive index lower than that of the substrate between the substrate and the first electrode.    9. A display device comprising: a light-emitting device according to claim 1; and a driving unit that controls light emission of the light-emitting device.   9. A lighting apparatus comprising: a light-emitting device according to claim 1; and a driving unit that controls light emission of the light-emitting device.

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