JP5238136B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light-emitting element using electroluminescence and a light-emitting device including the same. The present invention also relates to an electric appliance using the light emitting element.

  A light-emitting element using a light-emitting material has features such as thin and light weight, high-speed response, and direct-current low-voltage driving, and is expected to be applied to a next-generation flat panel display. Further, it is said that a light-emitting device in which light-emitting elements are arranged in a matrix has an advantage in that it has a wide viewing angle and excellent visibility as compared with a conventional liquid crystal display device.

  The basic structure of the light-emitting element is such that a layer containing a light-emitting organic compound (light-emitting layer) is sandwiched between a pair of electrodes. By applying a voltage to this element, electrons and holes are respectively transported from the pair of electrodes to the light emitting layer, and a current flows. Then, these carriers (electrons and holes) recombine, whereby the light-emitting organic compound forms an excited state, and emits light when the excited state returns to the ground state.

  Note that the excited states formed by the organic compound can be singlet excited state or triplet excited state. Light emission from the singlet excited state is called fluorescence, and light emission from the triplet excited state is called phosphorescence. ing.

  Such a light-emitting element is formed of an organic thin film having a thickness of, for example, about 0.1 μm. In addition, since the time from the injection of the carrier to the light emission is about microseconds or less, one of the features is that the response speed is very fast. Further, since sufficient light emission can be obtained with a DC voltage of several volts to several tens of volts, power consumption is relatively small. Because of these advantages, the light-emitting element has attracted attention as a next-generation flat panel display element.

  In addition, since the light-emitting element is formed in a film shape, planar light emission can be easily obtained by forming a large-area element. This is a feature that is difficult to obtain with a point light source typified by an incandescent bulb or LED, or a line light source typified by a fluorescent lamp, and therefore has a high utility value as a surface light source applicable to illumination or the like.

  However, these light-emitting elements have problems in durability and heat resistance, which greatly hinders the development of light-emitting elements. Since the light emitting element is usually formed by laminating organic thin films using organic compounds as represented by Non-Patent Document 1 below, the above-mentioned problems are the low durability of organic compounds and the weakness of organic thin films. This is considered to be a factor.

  On the other hand, an attempt has been made to form a light-emitting element using a layer in which an organic compound and an inorganic compound are mixed instead of an organic thin film. For example, Patent Document 1 below discloses a light-emitting element using a light-emitting layer in which fluorescent organic molecules are dispersed in a metal oxide. Patent Document 2 below also discloses a light-emitting element formed by laminating a layer in which an organic compound (a hole transporting compound, an electron transporting compound, or a light emitting compound) is dispersed through a covalent bond in a silica matrix. Yes. In these documents, it is reported that the durability and heat resistance of the element are improved.

  In the light-emitting elements disclosed in Patent Document 1 and Patent Document 2 described above, since an organic compound is only dispersed in an insulating metal oxide, a current flows as compared with a conventional light-emitting element. There is a problem that it becomes difficult (that is, the voltage required to pass a certain current increases).

  Since these light emitting elements have higher emission luminance in proportion to the current density to flow, the fact that the current does not flow easily means that the voltage for obtaining a certain luminance (that is, the driving voltage) also increases. . Therefore, if the organic compound is simply dispersed in the metal oxide, even if durability and heat resistance are obtained, an increase in driving voltage and an accompanying increase in power consumption are caused.

Further, in order to suppress a short circuit of the light emitting element due to dust or the like, it is effective to increase the film thickness of the light emitting element, but the configuration as shown in Patent Document 1 or Patent Document 2 is effective. When the film thickness is increased, the increase in drive voltage becomes more apparent. That is, in the conventional configuration, it is practically difficult to increase the film thickness.
C. W. Tan (C.W. Tang), 1 outside, Applied Physics Letters, Vol. 51, no. 12, 913-915 (1987) JP-A-2-288092 JP 2000-306669 A

  In view of the above problems, an object of the present invention is to provide a light emitting element with a low driving voltage. It is another object of the present invention to provide a light emitting device having such a light emitting element. The present invention also relates to an electric appliance using a light-emitting element with a low driving voltage.

The inventors mix a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and use a layer that includes a mixed material having a resistivity of 5 × 10 ⁴ to 10 × 10 ⁵ Ω · cm. Thus, it has been found that the driving voltage of the light emitting element can be reduced.

That is, the light-emitting element of the present invention includes a layer containing a light-emitting substance and a layer containing a mixed material containing a conductive material that is an inorganic compound and an insulating material that is an inorganic compound between a pair of electrodes. The layer containing the mixed material has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm. More preferably, the resistivity is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm.

  In the above structure, the layer containing the mixed material is in contact with at least one of the pair of electrodes.

  In the above structure, the layer containing the mixed material has a visible light transmittance of 80 to 100%.

  In the above structure, the insulating material is preferably any one of a metal oxide, a metal nitride, and a metal oxynitride. Specifically, silicon oxide, germanium oxide, titanium oxide, molybdenum oxide, aluminum oxide, silicon nitride, aluminum nitride, silicon oxynitride, and the like can be given.

  In the above structure, the conductive material is a transparent conductive film material. Specifically, the conductive material includes any of indium oxide, zinc oxide, tin oxide, cadmium oxide, and gallium oxide.

  The present invention also includes a light-emitting device that includes the above-described light-emitting element and a control unit that controls light emission of the light-emitting element. The light-emitting device in this specification includes an image display device, a light-emitting device, or a light source (including a lighting device). In addition, a module in which a connector such as an FPC (Flexible Printed Circuit) or TAB (Tape Automated Bonding) tape or TCP (Tape Carrier Package) is attached to the light emitting device, or a printed wiring board provided on the end of the TAB tape or TCP In addition, a module in which an IC (integrated circuit) is directly mounted on a light emitting element by a COG (Chip On Glass) method is also included in the light emitting device.

  In addition, the present invention includes in its category an electric appliance that includes a display portion, and the display portion includes the above-described light emitting element and a control unit that controls light emission of the light emitting element.

It includes a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm, preferably 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm. By using a layer containing a certain mixed material, the driving voltage of the light-emitting element can be reduced.

It includes a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm, preferably 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm. By using a layer containing a mixed material for the light-emitting element, an increase in driving voltage can be suppressed even when the layer containing the mixed material is thickened.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

  Note that in the present invention, light emission is obtained when a voltage is applied so that the potential of one of the pair of electrodes of the light-emitting element becomes higher. In that case, an electrode having a high potential is called an electrode functioning as an anode, and the other electrode having a low potential is called an electrode functioning as a cathode.

(Embodiment 1)
In this embodiment mode, a mixed material used for the light-emitting element of the present invention will be described.

  The mixed material used in the present invention includes a conductive material that is an inorganic compound and an insulating material that is an inorganic compound. The conductive material is desirably a material having a high visible light transmittance. For example, indium tin oxide (ITO) in which tin oxide is added to indium oxide, or conductive material (ITO in which titanium oxide is added to indium oxide). Zinc oxide-based materials containing zinc oxide, such as indium oxide containing indium oxide such as AZO with aluminum oxide added to zinc oxide, GZO with zinc oxide added with gallium oxide, and IZO with indium added to zinc oxide. And tin oxide-based materials obtained by adding antimony oxide or fluorine to tin oxide, cadmium oxide-based materials, gallium oxide-based materials, and the like.

As the insulating material, it is preferable to use a metal oxide, a metal nitride, a metal oxynitride, or the like. Specifically, silicon oxide, germanium oxide, titanium oxide, molybdenum oxide, aluminum oxide, silicon nitride, aluminum nitride, and the like can be given. The insulating material is preferably a material having a high visible light transmittance. Examples of the material having a high visible light transmittance include SiO ₂ , GeO ₂ , TiO ₂ , and Al ₂ O ₃ . By using an insulating material having a high visible light transmittance, the transmittance of the mixed material can be increased.

It is preferable that the resistivity of the layer containing the mixed material containing these conductive materials and insulating materials is 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm. More preferably, it is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm. By mixing a conductive material and an insulating material so as to have a resistivity in this range, low voltage driving of the light emitting element can be realized.

  Note that when the resistivity of the layer including the mixed material is too large, the driving voltage of the light emitting element is increased. Further, if the resistivity is too small, there is a possibility that crosstalk with adjacent light emitting elements occurs. Crosstalk means that electric leakage occurs between light emitting elements.

  For example, as illustrated in FIG. 10, a light-emitting element that emits a red color (R), a green color (G), and a blue color (B) includes a first electrode 1101 that is a reflective electrode, and a light-transmitting property. A second electrode 1102 having a first layer 1111R, 1111G, 1111B, a second layer 1112R, 1112G, 1112B, a third layer 1113R, 1113G, 1113B, a fourth layer 1114R, In the case of having 1114G and 1114B, the first electrode 1101 of the light emitting element of green color (G) and the second electrode 1102 of the light emitting element of red color (R) are short-circuited to cause electric leakage. Is called crosstalk.

Therefore, the mixed material using the conductive material and the insulating material of the present invention preferably has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm. In particular, it is more preferable that it is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm.

  The mixed material used in the present invention preferably has a visible light transmittance of 80 to 100%. Since the mixed material used in the present invention has a high visible light transmittance, light emitted from the light emitting layer can be efficiently extracted to the outside.

  In addition, since the mixed material used in the present invention has high visible light transmittance, reduction in light extraction efficiency can be suppressed even when the layer including the mixed material is thickened. Therefore, it is possible to optimize the thickness of the layer including the mixed material so that the efficiency of extracting light to the outside is increased while suppressing an increase in driving voltage.

  Further, it is possible to increase the thickness of the layer containing the mixed material in order to prevent a short circuit due to dust or impact.

The layer containing the mixed material used in the present invention can be formed by a sputtering method. At this time, a target including a conductive material made of an inorganic compound and an insulating material made of an inorganic compound is used as the target. By changing the composition ratio between the conductive material and the insulating material included in the target, a layer containing a mixed material having a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm can be obtained.

A layer containing the mixed material can also be formed by co-sputtering using a target of a conductive material made of an inorganic compound and a target of an insulating material made of an inorganic compound. In this case, by changing the area of each target, it is possible to change the composition ratio between the conductive material and the insulating material of the layer including the mixed material, and the resistivity is 5 × 10 ⁴ to 1 × 10 6. A layer containing a mixed material that is ⁶ Ω · cm can be formed.

  As a method for manufacturing the target, the powder of the conductive material and the powder of the insulating material can be mixed by a ball mill or the like, pressed, and then heated and sintered. A layer including the mixed material of the present invention is formed using the target thus manufactured.

  As a film forming atmosphere, an inert gas such as an argon gas is used. When oxygen is contained in the conductive material or the insulating material, it is preferable to mix oxygen gas with the inert gas. If oxygen gas is not mixed, oxygen may be released when a layer containing a mixed material is formed, which may cause a composition shift.

  Further, the layer containing the mixed material of the present invention can also be formed using a multi-source sputtering method. By using a target made of a conductive material and a target made of an insulating material and applying high frequency power to each, a layer containing the mixed material of the present invention can be formed. At this time, the resistivity of the obtained mixed material can be controlled by changing the magnitude of the applied high frequency power. For example, if the high-frequency power applied to the target made of an insulating material is increased, the proportion of the insulating material contained in the mixed material increases, and if the high-frequency power applied to the target made of a conductive material is increased, it is included in the mixed material. The ratio of the conductive material to be increased.

  In addition, when forming the layer containing the mixed material of the present invention on the organic compound, the mixed material is used by using an opposed target sputtering apparatus in which the plasma generation region and the film formation region are separated in order to reduce damage to the organic compound. It is preferable to form a layer containing. In the facing target type sputtering apparatus, a substrate is arranged at a position facing a pair of targets that are parallel to each other and a space between the targets, and the plasma generation region and the film formation region are separated from each other. The formed organic compound layer can be protected from damage caused by plasma.

  Note that in this specification, a material having a high visible light transmittance preferably has a visible light transmittance of 80 to 100%.

(Embodiment 2)
The light-emitting element of the present invention has a plurality of layers between a pair of electrodes. The plurality of layers have a high carrier injection property and carrier transport so that a light emitting region is formed at a position away from the electrode, that is, a carrier (carrier) is recombined at a position away from the electrode. The layers are formed by combining layers made of highly specific materials.

  One mode of the light-emitting element of the present invention will be described below with reference to FIG.

  In this embodiment, the light-emitting element includes a first electrode 102, a first layer 103, a second layer 104, a third layer 105, and a fourth layer 106 that are sequentially stacked over the first electrode 102. And a second electrode 107 provided thereon. Note that in this embodiment mode, the first electrode 102 functions as an anode and the second electrode 107 functions as a cathode.

  The substrate 101 is used as a support for the light emitting element. As the substrate 101, for example, glass or plastic can be used. Note that other materials may be used as long as the light-emitting element functions as a support in the manufacturing process.

  As the first electrode 102, various metals, alloys, electrically conductive compounds, and mixtures thereof can be used. For example, indium tin oxide (ITO), indium tin oxide containing silicon, IZO (Indium Zinc Oxide) in which 2 to 20 wt% zinc oxide (ZnO) is mixed with indium oxide, oxidized to indium oxide In addition to a conductive material (ITO) to which titanium is added, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt ( Co), titanium (Ti), copper (Cu), palladium (Pd), aluminum (Al), aluminum-silicon (Al-Si), aluminum-titanium (Al-Ti), aluminum-silicon-copper (Al-Si) -Cu) or a nitride of metal material (TiN) can be used. When used as a pole, among them, it is preferably formed like a large (work function 4.0eV or higher) work function material.

  Note that in the light-emitting element of the present invention, the first electrode 102 is not limited to a material having a high work function, and a material having a low work function can also be used.

The first layer 103 is a layer including a mixed material including the conductive material that is an inorganic compound and the insulating material that is an inorganic compound described in Embodiment 1, and has a resistivity of 5 × 10 ⁴ to 1 ×. It is preferably 10 ⁶ Ω · cm. More preferably, it is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm.

Note that the first layer 103 is not limited to a single layer as described above, but includes, for example, a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and two layers having different mixing ratios. A stacked structure may be used.

The second layer 104 is formed using a substance having a high hole-transport property, such as 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: α-NPD) or N, N′—. Bis (3-methylphenyl) -N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviation: TPD), 4,4 ′, 4 ″ -tris (N, N -Diphenylamino) aromatic such as triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA) It is a layer made of an amine-based compound (that is, having a benzene ring-nitrogen bond). The substances described here are mainly substances having a hole mobility of 10 ⁻⁶ cm ² / Vs or higher. Note that other than these substances, any substance that has a property of transporting more holes than electrons may be used. Note that the second layer 104 is not limited to a single layer, and may be a stack of two or more layers including any of the above substances.

The third layer 105 is a layer including a substance having a high light-emitting property. For example, a highly luminescent substance such as N, N′-dimethylquinacridone (abbreviation: DMQd) or 3- (2-benzthiazoyl) -7-diethylaminocoumarin (abbreviation: coumarin 6) and tris (8-quinolinolato) aluminum (abbreviation) : Alq ₃ ) and 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), etc., which are freely combined with a material having high carrier transportability and good film quality (that is, difficult to crystallize). However, since Alq ₃ and DNA are highly luminescent materials, these materials may be used alone, and the third layer 105 may be used.

The fourth layer 106 is formed using a substance having a high electron-transport property, such as tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (5-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10 -Hydroxybenzo [h] -quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq), etc., having a quinoline skeleton or a benzoquinoline skeleton It is a layer made of a metal complex or the like. In addition, bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (abbreviation: Zn ( A metal complex having an oxazole-based or thiazole-based ligand such as BTZ) ₂ ) can also be used. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5 -(P-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-tert-butylphenyl) -4-phenyl-5 (4-Biphenylyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2 , 4-triazole (abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), and the like can also be used. The substances mentioned here are mainly substances having an electron mobility of 10 ⁻⁶ cm ² / Vs or higher. Note that a substance other than the above substances may be used for the fourth layer 106 as long as it has a property of transporting more electrons than holes. The fourth layer 106 is not limited to a single layer, and may be a stack of two or more layers formed using the above substances.

  As a material for forming the second electrode 107, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function (a work function of 3.8 eV or less) can be used. Specific examples of such a cathode material include elements belonging to Group 1 or Group 2 of the periodic table of elements, that is, alkali metals such as lithium (Li) and cesium (Cs), and magnesium (Mg), calcium (Ca), Examples thereof include alkaline earth metals such as strontium (Sr) and alloys containing them (Mg: Ag, Al: Li). However, by providing a layer having a function of accelerating electron injection between the second electrode 107 and the light-emitting layer by stacking with the second electrode, regardless of the work function, Al, Ag, Various conductive materials such as ITO and ITO containing silicon can be used for the second electrode 107.

Note that as a layer having a function of promoting electron injection, an alkali metal or alkaline earth metal compound such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), or the like is used. Can do. In addition, a layer made of a substance having an electron transporting property containing an alkali metal or an alkaline earth metal, for example, a layer containing magnesium (Mg) in Alq ₃ can be used.

  Various methods can be used for forming the first layer 103, the second layer 104, the third layer 105, and the fourth layer 106. For example, a sputtering method, a vapor deposition method, an inkjet method, a spin coating method, or the like may be used. Moreover, you may form using the different film-forming method for each electrode or each layer.

  The light-emitting element of the present invention having the above structure is a third layer that contains a highly light-emitting substance because a current flows due to a potential difference generated between the first electrode 102 and the second electrode 107. In the layer 105, holes and electrons recombine to emit light. That is, a light emitting region is formed in the third layer 105. However, it is not necessary that all of the third layer 105 functions as a light emitting region. For example, the light emitting region is formed only on the second layer 104 side or the fourth layer 106 side of the third layer 105. It may be anything.

  Light emission is extracted outside through one or both of the first electrode 102 and the second electrode 107. Therefore, one or both of the first electrode 102 and the second electrode 107 is formed using a light-transmitting substance. In the case where only the first electrode 102 is made of a light-transmitting substance, light emission is extracted from the substrate side through the first electrode 102 as shown in FIG. Further, in the case where only the second electrode 107 is made of a light-transmitting substance, light emission is extracted from the opposite side of the substrate through the second electrode 107 as shown in FIG. When both the first electrode 102 and the second electrode 107 are made of a light-transmitting substance, as shown in FIG. 1C, light is emitted from the first electrode 102 and the second electrode 107. And is taken out from both the substrate side and the opposite side of the substrate.

Note that the structure of the layers provided between the first electrode 102 and the second electrode 107 is not limited to the above. A structure in which holes and electrons are recombined in a portion away from the first electrode 102 and the second electrode 107 so that quenching caused by the proximity of the light emitting region and the metal is suppressed. And includes a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm, more preferably 2 × 10 ^{5 to} 5 ×. Any other layer may be used as long as it has a layer of 10 ⁵ Ω · cm.

In other words, the layered structure of the layers is not particularly limited, and a substance having a high electron transporting property or a substance having a high hole transporting property, a substance having a high electron injecting property, a substance having a high hole injecting property, or a bipolar property (electron and hole) The layer made of the substance having a high transportability) may be freely combined with the layer containing the mixed material of the present invention. Alternatively, a carrier recombination site may be controlled by providing a layer made of a silicon oxide film or the like over the first electrode 102.

  A light-emitting element illustrated in FIG. 2 includes a first layer 303 formed using a substance having a high electron-transport property, a second layer 304 containing a substance having a high light-emitting property, and a hole transport over the first electrode 302 functioning as a cathode. A third layer 305 made of a highly specific substance, a fourth layer 306 which is a layer containing the mixed material of the present invention, and a second electrode 307 functioning as an anode are sequentially stacked. Reference numeral 301 denotes a substrate.

  In this embodiment mode, a light-emitting element is manufactured over a substrate made of glass, plastic, or the like. A passive light-emitting device can be manufactured by manufacturing a plurality of such light-emitting elements over one substrate. Alternatively, for example, a thin film transistor (TFT) may be formed over a substrate made of glass, plastic, or the like, and a light-emitting element may be formed over an electrode electrically connected to the TFT. Thus, an active matrix light-emitting device in which driving of the light-emitting element is controlled by the TFT can be manufactured. Note that the structure of the TFT is not particularly limited. A staggered TFT or an inverted staggered TFT may be used. Further, there is no particular limitation on the crystallinity of the semiconductor used for the TFT, and an amorphous semiconductor or a crystalline semiconductor may be used. Also, the driving circuit formed on the TFT array substrate may be composed of N-type and P-type TFTs, or may be composed of only one of N-type and P-type.

The light-emitting element of the present invention has a layer containing a mixed material containing a conductive material and an insulating material, and the resistivity of the layer containing the mixed material is more preferably 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm. Since it is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm, it is possible to realize low-voltage driving of the light-emitting element.

  In addition, since the mixed material used in the present invention has a high visible light transmittance, light emitted from the light-emitting layer can be efficiently extracted to the outside.

  In addition, since the mixed material used in the present invention has high visible light transmittance, reduction in light extraction efficiency can be suppressed even when the layer including the mixed material is thickened. Therefore, it is possible to optimize the thickness of the layer including the mixed material so that the efficiency of extracting light to the outside is increased while suppressing an increase in driving voltage.

  In addition, by increasing the thickness of the layer containing a mixed material, a short circuit due to dust, impact, or the like can be prevented; thus, a highly reliable light-emitting element can be obtained. For example, the film thickness between electrodes of a normal light emitting element is 100 nm to 150 nm, whereas the film thickness between electrodes of a light emitting element using a layer containing a mixed material is 100 to 500 nm, preferably 200 to 500 nm. It can be.

  In addition, the layer containing the mixed material used for the light-emitting element of the present invention can be in ohmic contact with the electrode and has low contact resistance with the electrode. Therefore, the electrode material can be selected without considering the work function or the like. That is, the choice of electrode material is expanded.

(Embodiment 3)
In this embodiment, a light-emitting element having a structure different from that described in Embodiment 2 will be described with reference to FIGS. In the structure described in this embodiment mode, a layer containing the mixed material of the present invention can be provided so as to be in contact with an electrode functioning as a cathode.

  FIG. 8A shows an example of the structure of the light-emitting element of the present invention. A first layer 411, a second layer 412, and a third layer 413 are stacked between the first electrode 401 and the second electrode 402. In this embodiment, the case where the first electrode 401 functions as an anode and the second electrode 402 functions as a cathode is described.

  The same structure as that in Embodiment 2 can be applied to the first electrode 401 and the second electrode 402. The first layer 411 is a layer containing a substance having high light-emitting properties. The second layer 412 is a layer including one compound selected from electron donating substances and a compound having a high electron-transport property, and the third layer 413 includes the mixed material described in Embodiment 1. Is a layer. The electron donating substance contained in the second layer 412 is preferably an alkali metal or alkaline earth metal and oxides or salts thereof. Specifically, lithium, cesium, calcium, lithium oxide, calcium oxide, barium oxide, cesium carbonate, and the like can be given.

  With such a configuration, as shown in FIG. 8A, when a voltage is applied, electrons are exchanged in the vicinity of the interface between the second layer 412 and the third layer 413. Holes are generated and the second layer 412 transports electrons to the first layer 411, while the third layer 413 transports holes to the second electrode 402. In other words, the second layer 412 and the third layer 413 together serve as a carrier generation layer. In addition, it can be said that the third layer 413 has a function of transporting holes to the second electrode 402.

  In addition, the third layer 413 exhibits extremely high hole injecting property and hole transporting property. Therefore, the drive voltage can be reduced. In addition, when the third layer 413 is thickened, an increase in driving voltage can be suppressed.

  Further, even if the third layer 413 is thickened, an increase in driving voltage can be suppressed. Therefore, the thickness of the third layer 413 can be set freely, and light emission from the first layer 411 can be extracted. Efficiency can be improved. In addition, the thickness of the third layer 413 can be set so that the color purity of light emission from the first layer 411 is improved. In addition, the third layer 413 has a high visible light transmittance, and can suppress a reduction in light extraction efficiency due to the increase in thickness.

  Note that the light-emitting element of this embodiment also has various variations by changing materials of the first electrode 401 and the second electrode 402. The schematic diagram is shown in FIG. 8 (b), FIG. 8 (c) and FIG. In FIGS. 8B, 8C, and 9, the reference numerals in FIG. 8A are cited. Reference numeral 400 denotes a substrate carrying the light emitting element of the present invention.

  FIG. 8 illustrates an example in which the first layer 411, the second layer 412, and the third layer 413 are configured in this order from the substrate 400 side. At this time, the first electrode 401 is made light-transmitting and the second electrode 402 is made light-shielding (particularly reflective) so that light is emitted from the substrate 400 side as shown in FIG. Become. In addition, the first electrode 401 is made light-shielding (particularly reflective), and the second electrode 402 is made light-transmissive so that light is emitted from the opposite side of the substrate 400 as shown in FIG. 8B. It becomes. Further, by making both the first electrode 401 and the second electrode 402 light transmissive, light is emitted to both the substrate 400 side and the opposite side of the substrate 400 as shown in FIG. Configuration is also possible.

  FIG. 9 illustrates an example in which the third layer 413, the second layer 412, and the first layer 411 are configured in this order from the substrate 400 side. At this time, the first electrode 401 is made light-shielding (particularly reflective), and the second electrode 402 is made light-transmissive so that light is extracted from the substrate 400 side as shown in FIG. . Further, the first electrode 401 is made light-transmitting and the second electrode 402 is made light-shielding (particularly reflective), whereby light is extracted from the opposite side of the substrate 400 as shown in FIG. 9B. Become. Further, by making both the first electrode 401 and the second electrode 402 light transmissive, light is emitted to both the substrate 400 side and the opposite side of the substrate 400 as shown in FIG. 9C. Configuration is also possible.

  In addition, as illustrated in FIG. 8, after the first electrode 401 is formed, the first layer 411, the second layer 412, and the third layer 413 are sequentially stacked to form the second electrode 402. Alternatively, as shown in FIG. 9, after the second electrode 402 is formed, the third layer 413, the second layer 412, and the first layer 411 are sequentially stacked to form the first electrode 401. May be.

  Note that this embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 4)
In this embodiment, a light-emitting element having a structure different from those described in Embodiments 2 and 3 will be described with reference to FIGS. In the structure described in this embodiment mode, a layer containing the mixed material of the present invention can be provided so as to be in contact with two electrodes of the light-emitting element.

  FIG. 3A shows an example of the structure of the light-emitting element of the present invention. A first layer 211, a second layer 212, a third layer 213, and a fourth layer 214 are stacked between the first electrode 201 and the second electrode 202. In this embodiment, the case where the first electrode 201 functions as an anode and the second electrode 202 functions as a cathode is described.

  The first electrode 201 and the second electrode 202 can have the same structure as that in Embodiment 2. The first layer 211 is a layer containing the mixed material described in Embodiment 1, and the second layer 212 is a layer containing a substance having a high light-emitting property. The third layer 213 is a layer including an electron donating substance and a compound having a high electron transporting property, and the fourth layer 214 is a layer including the mixed material described in Embodiment Mode 1. The electron donating substance contained in the third layer 213 is preferably an alkali metal or alkaline earth metal and oxides or salts thereof. Specifically, lithium, cesium, calcium, lithium oxide, calcium oxide, barium oxide, cesium carbonate, and the like can be given.

  With such a configuration, as shown in FIG. 3A, when a voltage is applied, electrons are transferred near the interface between the third layer 213 and the fourth layer 214, and the electrons and Holes are generated and the third layer 213 transports electrons to the second layer 212, while the fourth layer 214 transports holes to the second electrode 202. That is, the third layer 213 and the fourth layer 214 together serve as a carrier generation layer. In addition, it can be said that the fourth layer 214 has a function of transporting holes to the second electrode 202. Note that a tandem light-emitting element can be obtained by stacking the second layer and the third layer again between the fourth layer 214 and the second electrode 202.

In addition, the first layer 211 and the fourth layer 214 exhibit extremely high hole injecting property and hole transporting property. Therefore, the driving voltage of the light emitting element can be reduced.
In addition, when the first layer 211 and the fourth layer 214 are thickened, an increase in driving voltage can be suppressed.

  Further, even if the first layer 211 and the fourth layer 214 are thickened, an increase in driving voltage can be suppressed. Therefore, the thicknesses of the first layer 211 and the fourth layer 214 can be freely set. In addition, the extraction efficiency of light emission from the second layer 212 can be improved. In addition, the thickness of the first layer 211 or the fourth layer 214 can be set so that the color purity of light emission from the second layer 212 is improved. In addition, the first layer 211 and the fourth layer 214 have high visible light transmittance, and can suppress a reduction in the efficiency of external extraction of light emission due to thickening.

Further, in the light emitting element of this embodiment, it is possible to make the anode side and cathode side layers of the second layer responsible for the light emitting function very thick and to effectively prevent a short circuit of the light emitting element. In addition, by forming the first layer 211 and the fourth layer 214 with the same material, a layer made of the same material can be provided on both sides of the layer responsible for the light emitting function, so that stress strain is suppressed. Can also be expected.

  Note that the light-emitting element of this embodiment also has various variations by changing materials of the first electrode 201 and the second electrode 202. The schematic diagram is shown in FIG. 3 (b), FIG. 3 (c) and FIG. In FIGS. 3B, 3C, and 4, the reference numerals in FIG. 3A are cited. Reference numeral 200 denotes a substrate carrying the light emitting element of the present invention.

  FIG. 3 shows an example in which the first layer 211, the second layer 212, the third layer 213, and the fourth layer 214 are configured in this order from the substrate 200 side. At this time, the first electrode 201 is light-transmitting and the second electrode 202 is light-shielding (particularly reflective) so that light is emitted from the substrate 200 side as shown in FIG. Become. Further, the first electrode 201 is made light-shielding (particularly reflective), and the second electrode 202 is made light-transmissive so that light is emitted from the opposite side of the substrate 200 as shown in FIG. It becomes. Further, by making both the first electrode 201 and the second electrode 202 light transmissive, light is emitted to both the substrate 200 side and the opposite side of the substrate 200 as shown in FIG. Configuration is also possible.

  FIG. 4 shows an example in which the fourth layer 214, the third layer 213, the second layer 212, and the first layer 211 are configured in this order from the substrate 200 side. At this time, the first electrode 201 is made light-shielding (particularly reflective), and the second electrode 202 is made light-transmissive so that light is extracted from the substrate 200 side as shown in FIG. . Further, the first electrode 201 is made light-transmitting and the second electrode 202 is made light-shielding (particularly reflective), whereby light is extracted from the opposite side of the substrate 200 as shown in FIG. Become. Furthermore, by making both the first electrode 201 and the second electrode 202 light transmissive, light is emitted to both the substrate 200 side and the opposite side of the substrate 200 as shown in FIG. Configuration is also possible.

  Note that the first layer 211 includes one compound selected from an electron-donating substance and a compound having a high electron-transport property, the second layer 212 includes a light-emitting substance, and the third layer. Reference numeral 213 denotes a layer including the mixed material described in Embodiment 1, and the fourth layer 214 includes one compound selected from the electron-donating substances and a compound having a high electron-transport property. It is also possible.

  Note that in the case of manufacturing the light-emitting element in this embodiment, various methods can be used regardless of a wet method or a dry method.

  Further, as illustrated in FIG. 3, after the first electrode 201 is formed, the first layer 211, the second layer 212, the third layer 213, and the fourth layer 214 are sequentially stacked. 4, or after forming the second electrode 202, as shown in FIG. 4, the fourth layer 214, the third layer 213, the second layer 212, and the first layer The layer 211 may be sequentially stacked to form the first electrode.

  Note that this embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 5)
In this embodiment mode, optical design of a light-emitting element will be described.

In the light-emitting elements described in any of Embodiments 2 to 4, light emission is achieved by changing the thickness of at least one of the layers excluding the first electrode and the second electrode for each light-emitting element that emits each emission color. The light extraction efficiency for each color can be increased.

For example, as illustrated in FIG. 10, a light-emitting element that emits a red color (R), a green color (G), and a blue color (B) includes a first electrode 1101 that is a reflective electrode, and a light-transmitting property. A second electrode 1102 having a first layer 1111R, 1111G, 1111B, a second layer 1112R, 1112G, 1112B, a third layer 1113R, 1113G, 1113B, a fourth layer 1114R, respectively. 1114G and 1114B. Then, the thicknesses of the first layers 1111R, 1111G, and 1111B are made different for each emission color.

Note that in the light-emitting element illustrated in FIG. 10, when voltage is applied so that the potential of the first electrode 1101 is higher than the potential of the second electrode 1102, holes are transferred from the first layer 1111 to the second layer 1112. Is injected. Electrons are transferred in the vicinity of the interface between the third layer 1113 and the fourth layer 1114, electrons and holes are generated, and the third layer 1113 transports electrons to the second layer 1112, and at the same time, The fourth layer 1114 transports holes to the second electrode 1102. Holes and electrons recombine in the second layer 1112 to bring the light-emitting substance into an excited state. The excited luminescent material emits light when returning to the ground state.

As shown in FIG. 10, by making the first layers 1111R, 1111G, and 1111B different for each emission color, the first layer 1111R, 1111G, 1111B are directly recognized through the second electrode, and the second layer is reflected by the first electrode. It is possible to prevent the light extraction efficiency from being lowered due to the difference in the optical path between the case of recognition through the electrode.

Specifically, when light is incident on the first electrode, phase inversion occurs in the reflected light, resulting in a light interference effect. As a result, the optical distance between the light emitting region and the reflective electrode, that is, the refractive index × distance is (2m−1) / 4 times the emission wavelength (m is an arbitrary positive integer), that is, 1/4, 3/4. When the ratio is 5/4, etc., the efficiency of taking out the emitted light is increased. On the other hand, when m / 2 times (m is an arbitrary positive integer), that is, 1/2, 1, 3/2.

Therefore, in the light emitting device of the present invention, the optical distance between the light emitting region and the reflective electrode, that is, the refractive index × distance is (2m−1) / 4 times the emission wavelength (m is an arbitrary positive integer). The film thickness of any of the first to fourth layers is made different for each light emitting element.

In particular, in the first layer to the fourth layer, the thickness of the layer between the layer where the electrons and holes are recombined and the reflective electrode may be different, but from the layer where the electrons and holes are recombined. The film thickness between the light-transmitting electrodes may be different. Furthermore, the film thicknesses of both may be different. As a result, the emitted light can be efficiently extracted outside.

In order to change the film thickness of any of the first layer to the fourth layer, it is necessary to increase the thickness of the layer. The light-emitting element of the present invention is characterized in that the layer containing the mixed material described in Embodiment Mode 1 is used for the layer to be thickened.

In general, when the thickness of the light emitting element layer is increased, the driving voltage increases, which is not preferable. However, when the mixed material described in Embodiment 1 is used for the layer to be thickened, the driving voltage itself can be lowered, and an increase in driving voltage due to the thickening can be suppressed.

  In FIG. 10, the optical distance between the light emitting region of the red light emitting element (R) and the reflective electrode is 1/4 times the light emitting wavelength, and the light emitting region of the green light emitting element (G) and the reflective electrode The optical distance is 3/4 times the emission wavelength, and the optical distance between the light emitting region of the blue light emitting element (B) and the reflective electrode is 5/4 times the emission wavelength. Note that the present invention is not limited to this value, and the value of m can be set as appropriate. As shown in FIG. 10, the value of m, which is (2m−1) / 4 times the emission wavelength, may be different for each light emitting element.

Further, by increasing the thickness of any of the first to fourth layers, the first electrode and the second electrode can be prevented from being short-circuited, and mass productivity can be improved. preferable.

As described above, in the light-emitting element of the present invention, at least the thickness of any of the first to fourth layers can be made different for each emission color. At this time, it is preferable that the film thickness of the layer between the layer where the electrons and holes are recombined and the reflective electrode be different for each emission color. The layer that needs to be thicker is preferably a layer containing the mixed material shown in Embodiment Mode 1 because the driving voltage is not increased.

  Note that although this embodiment mode is described using the light-emitting element having the structure described in Embodiment Mode 4, it can be combined with any other embodiment mode as appropriate.

(Embodiment 6)
In this embodiment mode, a light-emitting device having the light-emitting element of the present invention will be described.

  In this embodiment mode, a light-emitting device having the light-emitting element of the present invention in a pixel portion will be described with reference to FIGS. 5A is a top view illustrating the light-emitting device, and FIG. 5B is a cross-sectional view taken along lines A-A ′ and B-B ′ in FIG. 5A. Reference numeral 601 indicated by a dotted line denotes a driving circuit portion (source side driving circuit), 602 denotes a pixel portion, and 603 denotes a driving circuit portion (gate side driving circuit). Reference numeral 604 denotes a sealing substrate, reference numeral 605 denotes a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

  Note that the routing wiring 608 is a wiring for transmitting a signal input to the source side driving circuit 601 and the gate side driving circuit 603, and a video signal, a clock signal, an FPC (flexible printed circuit) 609 serving as an external input terminal, Receives start signal, reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.

  Next, a cross-sectional structure is described with reference to FIG. A driver circuit portion and a pixel portion are formed over the element substrate 610. Here, a source-side driver circuit 601 that is a driver circuit portion and one pixel in the pixel portion 602 are illustrated.

  Note that the source side driver circuit 601 is a CMOS circuit in which an n-channel TFT 623 and a p-channel TFT 624 are combined. The TFT forming the driving circuit may be formed by various CMOS circuits, PMOS circuits, or NMOS circuits. Further, in this embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown, but this is not always necessary, and it can be formed outside the substrate.

  The pixel portion 602 is formed by a plurality of pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof. Note that an insulator 614 is formed so as to cover an end portion of the first electrode 613. Here, a positive photosensitive acrylic resin film is used.

  In order to improve the coverage, a curved surface having a curvature is formed at the upper end or the lower end of the insulator 614. For example, when positive photosensitive acrylic is used as a material for the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface with a curvature radius (0.2 μm to 3 μm). As the insulator 614, either a negative type that becomes insoluble in an etchant by light irradiation or a positive type that becomes soluble in an etchant by light can be used.

  Over the first electrode 613, the stacked body 616 including the layer containing the mixed material and the layer containing a light-emitting substance described in Embodiment 1 and the second electrode 617 are formed. Here, as a material used for the first electrode 613 functioning as an anode, a material having a high work function is preferably used. For example, an ITO film or an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt% zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, or the like In addition, a stack of a titanium nitride film and a film containing aluminum as a main component, a three-layer structure including a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film can be used. Note that with a stacked structure, resistance as a wiring is low, good ohmic contact can be obtained, and a function as an anode can be obtained.

The layer including the mixed material described in Embodiment 1 includes a conductive material that is an inorganic compound and an insulating material that is an inorganic compound, and the resistivity is preferably 5 × 10 ⁴ to 1 × 10 ⁶ Ω. • cm, more preferably a layer that is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm.

  In addition, the layer containing a light-emitting substance is formed by various methods such as an evaporation method using an evaporation mask, an inkjet method, and a spin coating method. The material constituting the layer containing a light-emitting substance may be a low molecular material, a medium molecular material (including oligomers and dendrimers), or a high molecular material. In addition, as a material used for a layer including a light-emitting substance, an organic compound is usually used in a single layer or a stacked layer. However, in the present invention, a structure in which an inorganic compound is used for part of a film formed of an organic compound is also included. I will do it.

Further, as a material used for the second electrode 617 which is formed over the stack 616 including a layer containing a mixed material and a layer containing a light-emitting substance and functions as a cathode, a material having a low work function (Al, Ag, li, Ca, or an alloy MgAg,, MgIn, AlLi, CaF 2, it is preferable to use a lithium fluoride or calcium nitride). Note that in the case where light generated in the stacked body 616 transmits the second electrode 617, the second electrode 617 includes a thin metal film and a transparent conductive film (ITO, 2 to 20 wt% oxidation). A stack of indium oxide containing zinc, indium tin oxide containing silicon, zinc oxide (ZnO), or the like is preferably used.

  Further, the sealing substrate 604 is bonded to the element substrate 610 with the sealant 605, whereby the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. Yes. Note that the space 607 includes a structure filled with a sealant 605 in addition to a case where the space 607 is filled with an inert gas (nitrogen, argon, or the like).

  Note that an epoxy-based resin is preferably used for the sealant 605. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), Mylar, polyester, acrylic, or the like can be used as a material for the sealing substrate 604.

  As described above, a light-emitting device having the light-emitting element of the present invention can be obtained.

The light-emitting device of the present invention has a layer containing a mixed material containing a conductive material and an insulating material, and the resistivity of the layer containing the mixed material is more preferably 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm. Is 2 × 10 ^{5 to} 5 × 10 ⁵ Ω · cm, so that the drive voltage can be reduced and the power consumption can be reduced.

  In addition, since the mixed material used in the present invention has a high visible light transmittance, light emitted from the light-emitting layer can be efficiently extracted to the outside.

  In addition, the light-emitting device of the present invention can suppress an increase in driving voltage even when the layer including the mixed material including the conductive material and the insulating material is thickened. Further, the mixed material used in the present invention has a high visible light transmittance. Therefore, the layer containing the mixed material can be thickened to prevent a short circuit of the light-emitting element. In addition, it is possible to realize an improvement in the efficiency of taking out emitted light by optical design. Thus, a light-emitting device with low power consumption and high reliability can be obtained.

  As described above, in this embodiment mode, an active light-emitting device that controls driving of a light-emitting element using a transistor has been described. In addition to this, a light-emitting element is driven without particularly providing a driving element such as a transistor. A passive light emitting device may be used. FIG. 6 is a perspective view of a passive light emitting device manufactured by applying the present invention. In FIG. 6, a stacked body 955 including a layer containing a light-emitting substance and a layer containing a mixed material shown in Embodiment Mode 1 is provided between an electrode 952 and an electrode 956 over a substrate 951. An end portion of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided over the insulating layer 953. The side wall of the partition wall layer 954 has an inclination such that the distance between one side wall and the other side wall becomes narrower as it approaches the substrate surface. That is, the cross section in the short side direction of the partition wall layer 954 has a trapezoidal shape, and the bottom side (the side facing the insulating layer 953 in the same direction as the surface direction of the insulating layer 953) is the top side (the surface of the insulating layer 953). The direction is the same as the direction and is shorter than the side not in contact with the insulating layer 953. In this manner, by providing the partition layer 954, defects in the light-emitting element due to static electricity or the like can be prevented. A passive light emitting device can also be driven with low power consumption by including the light emitting element of the present invention that operates at a low driving voltage.

(Embodiment 7)
In this embodiment, one mode of a light-emitting device including a light-emitting element and a transistor that controls operation of the light-emitting element is described with reference to FIGS.

  In FIG. 11, the light-emitting element has a structure in which a stacked body 502 is sandwiched between a first electrode 501 and a second electrode 503. The layered body is composed of 502, a layer containing a light emitting substance, and a layer containing a mixed material, the details of which are shown in the first to fifth embodiments. The peripheral end portion of the first electrode is covered with a partition layer 512 formed of an electrically insulating organic resin material or inorganic material. The stacked body 502 and the second electrode 503 are provided in the opening of the partition layer 512, that is, the exposed portion of the first electrode 501, so that the light-emitting element in the light-emitting device is formed. .

  The transistor that controls the operation of the light-emitting element includes a semiconductor layer 504 and a gate electrode 505 that overlaps the semiconductor layer with the gate insulating layer 506 provided therebetween. The gate electrode 505 may be provided with a conductive layer made of a metal such as tungsten, molybdenum, titanium, or tantalum, or an oxide or nitride of the metal on a lower layer side of the metal layer.

  The light-emitting element and the transistor are connected to each other by a wiring that penetrates the gate insulating layer 506, the first interlayer insulating layer 507, and the second interlayer insulating layer 508. The wiring is for electrically connecting different elements and desirably has a low resistance. However, when aluminum is used as an electrode, there is a problem that if the surface is oxidized, the contact resistance increases and a good contact cannot be formed. In the case of this embodiment, when ITO is used for the first electrode of the light emitting element, the surface of aluminum may be oxidized, and the contact resistance may increase due to electrical contact.

  Thus, in the light-emitting device described in this embodiment, a wiring is formed using the first conductive layer 509 and the second conductive layer 510. The first conductive layer 509 is formed using a conductive material that exhibits conductivity even when oxidized or a conductive material that does not oxidize. Typically, a metal such as titanium, tantalum, tungsten, chromium, nickel, molybdenum, or a nitride or oxide of these metals is used. The second conductive layer 510 is formed using aluminum or an alloy or compound containing aluminum. Further, an insulating layer 511 is formed over the second conductive layer 510. The insulating layer 511 is provided to prevent the surface of the second conductive layer 510 from being oxidized or corroded. As the insulating layer 511, a material that does not easily react with the second conductive layer 510 is preferable, and a photoresist, polyimide, acrylic, other organic fat materials, silicon nitride, silicon oxide, or other inorganic insulating materials are used. can do.

  This wiring is formed so that the width of the first conductive layer 509 is wider than the width of the second conductive layer 510. That is, the first conductive layer 509 protrudes from the second conductive layer 510. The cross-sectional shape of the wiring can be seen as a hat-type with a collar (hat-type). In the connection portion with the light-emitting element, the first electrode 501 is in contact with the side end portion of the first conductive layer 509 and the upper surface portion protruding from the second conductive layer 510. The first electrode 501 further extends from the side surface portion of the second conductive layer 510 and the side surface portion of the insulating layer 511 to the upper surface portion. As described above, the first electrode 501 is in electrical contact with at least the first conductive layer 509 forming a wiring. With such a structure, even when the aluminum surface is oxidized, the wiring and the light emitting element can be electrically connected.

  In addition to ITO, the first electrode 501 includes indium tin oxide (ITSO) containing silicon, indium tin zinc oxide (IZO) in which indium oxide is mixed with 2 to 20 wt% zinc oxide (ZnO), and gallium. Zinc oxide (GZO) added, conductive material (ITO) obtained by adding titanium oxide to indium oxide, zinc oxide (ZnTiO) added with titanium oxide, or the like can be used. In any case, it is desirable that the first electrode 501 includes an element or a compound that inhibits crystallization of indium oxide or zinc oxide so that the surface becomes flat.

  When titanium oxide is included in indium oxide or zinc oxide, the wettability of the surface can be improved. Accordingly, in the case where the stacked body 502 is formed by a wet method using an inkjet printing technique or a spin coating technique, indium oxide or zinc oxide containing titanium oxide can be suitably used. Further, in the case where the first electrode 501 is formed by sputtering using indium oxide as a target, generation of abnormal discharge can be suppressed because titanium oxide exhibits conductivity, so that powder in the film formation process can be suppressed. Contamination and generation of pinholes in the first electrode 501 can be suppressed. In this case, a target containing 1 to 20 wt%, preferably 3 to 10 wt% of titanium oxide with respect to indium oxide may be used.

  Note that although the case where two layers of the first conductive layer 509 and the second conductive layer 510 are used as the structure of the wiring is illustrated in this embodiment mode, the present invention is not limited to such a form, and the electrical resistance is Combines a layer containing a low conductive material with a layer containing a conductive material that shows conductivity even when oxidized or a layer containing a conductive material that does not oxidize. You may form the wiring to express.

  FIG. 12 shows the configuration of the input terminal portion of the light emitting device. A connection terminal 513 for connection to an external circuit is formed using the same conductive material as that of the gate electrode 505. The connection terminal 513 is exposed through the opening from which the first interlayer insulating layer 507 and the second interlayer insulating layer 508 are removed. A conductive layer 514 formed of the same conductive material as the first electrode 501 is formed on the exposed surface so as to cover the surface of the connection terminal 513 in order to protect the surface. Further, this connection terminal may be provided so as to be connected to a wiring formed of the first conductive layer 509 and the second conductive layer 510. Note that an insulating layer 511 is formed over the second conductive layer 510.

  As described above, according to the light-emitting device of this embodiment, a layer including a light-emitting substance, a layer including a mixed material in which a conductive material that is an inorganic compound and an insulating material that is an inorganic compound are mixed. By using a wiring that can maintain a good electrical connection between the light-emitting element provided and a transistor that controls the operation of the light-emitting element, power consumption of the light-emitting device can be reduced. In other words, by providing a layer containing a mixed material, the driving voltage of the light-emitting element can be reduced, and an increase in contact resistance between the electrode and the wiring of the light-emitting element can be prevented, so that power consumption can be further reduced. .

(Embodiment 8)
In this embodiment mode, a mode of an electric appliance according to the present invention will be described with reference to FIG.

  FIG. 7A illustrates a television device according to the present invention, which includes a housing 9101, a supporting base 9102, a display portion 9103, a speaker portion 9104, a video input terminal 9105, and the like. In this television device, the display portion 9103 is formed by arranging light-emitting elements similar to those described in Embodiment Modes 2 to 5 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high and a short circuit due to dust or an impact can be prevented. Since the display portion 9103 including the light-emitting elements has similar features, this television set has no deterioration in image quality and low power consumption. With such a feature, the deterioration compensation function and the power supply circuit can be significantly reduced or reduced in the television device, so that the housing 9101 and the support base 9102 can be reduced in size and weight. In the television device according to the present invention, low power consumption, high image quality, and reduction in size and weight are achieved, so that a product suitable for a living environment can be provided.

  FIG. 7B illustrates a computer according to the present invention, which includes a main body 9201, a housing 9202, a display portion 9203, a keyboard 9204, an external connection port 9205, a pointing mouse 9206, and the like. In this computer, the display portion 9203 is formed by arranging light-emitting elements similar to those described in Embodiment Modes 2 to 5 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high and a short circuit due to dust or an impact can be prevented. Since the display portion 9203 including the light-emitting elements has similar features, this computer has no deterioration in image quality and has low power consumption. With such a feature, the deterioration compensation function and the power supply circuit can be significantly reduced or reduced in the computer, so that the main body 9201 and the housing 9202 can be reduced in size and weight. In the computer according to the present invention, low power consumption, high image quality, and reduction in size and weight are achieved; therefore, a product suitable for a living environment can be provided. In addition, the computer can be carried, and a computer having a display portion that is resistant to impact when being carried can be provided.

  FIG. 7C illustrates a goggle type display according to the present invention, which includes a main body 9301, a display portion 9302, and an arm portion 9303. In this goggle type display, the display portion 9302 is formed by arranging light-emitting elements similar to those described in Embodiment Modes 2 to 5 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high and a short circuit due to dust or an impact can be prevented. Since the display portion 9302 including the light-emitting elements has similar features, the goggle-type display has no deterioration in image quality and has low power consumption. With such a feature, in the goggle type display, the deterioration compensation function and the power supply circuit can be significantly reduced or reduced, so that the main body 9301 can be reduced in size and weight. Since the goggle type display according to the present invention achieves low power consumption, high image quality, and small size and light weight, it is possible to provide a product that can be used without a sense of incongruity with less burden when worn. Further, it is possible to provide a goggle-type display having a display portion that is resistant to impacts when mounted and moved.

  FIG. 7D illustrates a cellular phone according to the present invention, which includes a main body 9401, a housing 9402, a display portion 9403, an audio input portion 9404, an audio output portion 9405, operation keys 9406, an external connection port 9407, an antenna 9408, and the like. . In this cellular phone, the display portion 9403 is formed by arranging light-emitting elements similar to those described in Embodiments 2 to 5 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high and a short circuit due to dust or an impact can be prevented. Since the display portion 9403 including the light-emitting elements has similar features, the cellular phone has no deterioration in image quality and low power consumption. With such a feature, the deterioration compensation function and the power supply circuit can be significantly reduced or reduced in the mobile phone, so that the main body 9401 and the housing 9402 can be reduced in size and weight. Since the cellular phone according to the present invention has low power consumption, high image quality, and reduced size and weight, a product suitable for carrying can be provided. In addition, a product having a display portion that is resistant to impact when carried can be provided.

  FIG. 7E illustrates a camera according to the present invention, which includes a main body 9501, a display portion 9502, a housing 9503, an external connection port 9504, a remote control receiving portion 9505, an image receiving portion 9506, a battery 9507, an audio input portion 9508, and operation keys 9509. , An eyepiece 9510 and the like. In this camera, the display portion 9502 is configured by arranging light-emitting elements similar to those described in Embodiment Modes 2 to 5 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high and a short circuit due to dust or an impact can be prevented. Since the display portion 9502 including the light-emitting elements has similar features, this camera has no deterioration in image quality and has low power consumption. With such a feature, a deterioration compensation function and a power supply circuit can be significantly reduced or reduced in the camera, so that the main body 9501 can be reduced in size and weight. Since the camera according to the present invention has low power consumption, high image quality, and small size and light weight, a product suitable for carrying can be provided. In addition, a product having a display portion that is resistant to impact when carried can be provided.

4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B each illustrate an electric appliance having a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. FIG. 6 illustrates one embodiment of a light-emitting device including a light-emitting element and a transistor that controls operation of the light-emitting element. FIG. 6 illustrates one embodiment of a connection terminal portion in a light-emitting device including a light-emitting element and a transistor that controls operation of the light-emitting element.

Explanation of symbols

101 substrate 102 first electrode 103 first layer 104 second layer 105 third layer 106 fourth layer 107 second electrode 200 substrate 201 first electrode 202 second electrode 211 first layer 212 2nd layer 213 3rd layer 214 4th layer 302 1st electrode 303 1st layer 304 2nd layer 305 3rd layer 306 4th layer 307 2nd electrode 400 substrate 401 1st Electrode 402 Second electrode 411 First layer 412 Second layer 413 Third layer 501 First electrode 502 Stack 503 Second electrode 504 Semiconductor layer 505 Gate electrode 506 Gate insulating layer 507 First interlayer insulation Layer 508 second interlayer insulating layer 509 first conductive layer 510 second conductive layer 511 insulating layer 512 partition wall 513 connection terminal 514 conductive layer 601 source side driver circuit 602 pixel portion 603 gate side Drive circuit 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 609 FPC (flexible printed circuit)
610 Element substrate 611 TFT for switching
612 Current control TFT
613 First electrode 614 Insulator 616 Stack 617 Second electrode 618 Light-emitting element 623 n-channel TFT
624 p-channel TFT
951 Substrate 952 Electrode 953 Insulating layer 954 Partition layer 955 Stack 956 Electrode 1101 First electrode 1102 Second electrode 1111 First layer 1112 Second layer 1113 Third layer 1114 Fourth layer 9101 Housing 9102 Support Base 9103 Display unit 9104 Speaker unit 9105 Video input terminal 9201 Main body 9202 Case 9203 Display unit 9204 Keyboard 9205 External connection port 9206 Pointing mouse 9301 Main body 9302 Display unit 9303 Arm unit 9401 Main unit 9402 Body 9403 Display unit 9404 Audio input unit 9405 Audio Output unit 9406 Operation key 9407 External connection port 9408 Antenna 9501 Main body 9502 Display unit 9503 Housing 9504 External connection port 9505 Remote control receiving unit 9506 Image receiving unit 9507 Battery 508 audio input portion 9509 operation key 9510 eyepiece

Claims (1)

A light-emitting device having a transistor and a light-emitting element,
The light-emitting element includes a first electrode, a second electrode, a first carrier generation layer in contact with the first electrode, a second carrier generation layer in contact with the second electrode, and the first A light emitting layer provided between the carrier generating layer and the second carrier generating layer,
Each of the first carrier generation layer and the second carrier generation layer includes a layer including a mixed material including a conductive material that is an inorganic compound and an insulating material that is an inorganic compound,
The layer containing the mixed material has a resistivity of 5 × 10 ⁴ to 1 × 10 ⁶ Ω · cm,
The transistor is electrically connected to a first conductive layer penetrating a first insulating layer provided on the transistor and a second conductive layer;
The light emitting element is electrically connected to the transistor by contacting the first electrode and at least the first conductive layer,
Having the second conductive layer on the first conductive layer;
A second insulating layer on the second conductive layer;
Having the first electrode on the first conductive layer and on the second insulating layer;
Width of the first conductive layer is widely than a width of the second conductive layer,
The first electrode includes a side surface portion of the first conductive layer, an upper surface portion of the first conductive layer protruding from the second conductive layer, and a side surface portion of the second conductive layer. A light-emitting device having a contact region .

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