JP4993939B2 - Light emitting element and 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.

In recent years, research and development of light-emitting elements using light-emitting organic compounds have been actively conducted. The basic structure of these light-emitting elements is such that a layer containing a light-emitting organic compound is sandwiched between a pair of electrodes. By applying a voltage to this element, electrons and holes are injected from the pair of electrodes to the layer containing a light-emitting organic compound, and 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. Due to such a mechanism, such a light-emitting element is referred to as a current-excitation light-emitting element.

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 1 μsec or less, one of the features is that the response speed is very fast. These characteristics are considered suitable for flat panel display elements.

In addition, since these light-emitting elements are 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.

  As described above, a current-excitation light-emitting element using a light-emitting organic compound is expected to be applied to a light-emitting device, illumination, and the like, but there are still many problems. One of the problems is reduction of power consumption. In order to reduce power consumption, it is important to reduce the driving voltage of the light emitting element. In the current excitation type light emitting element, since the light emission intensity is determined by the amount of flowing current, it is necessary to flow a large amount of current at a low voltage in order to reduce the driving voltage.

  According to Patent Document 1, the driving voltage of the light emitting device can be reduced by doping the organic layer in contact with the anode with an electron accepting compound having a property capable of oxidizing the organic compound constituting the organic layer. There is a report. In addition, since the organic layer doped with the electron-accepting dopant does not increase the voltage of the device even if it is thick, the distance between the electrodes can be set longer than usual, greatly increasing the risk of short circuit. It is described as being useful as a means of mitigation.

  On the other hand, attempts have been made to improve the external light extraction efficiency of the light emitting element by adjusting the optical distance. According to Patent Document 2, it is described that the emission spectrum is controlled by changing the layer thickness of an organic compound layer doped with an electron-accepting compound provided at the interface of the anode on the light-emitting layer side.

  The organic compound layer doped with the electron-accepting compound described in Patent Document 1 and Patent Document 2 is doped with the electron-accepting compound by a co-evaporation method, or the organic compound and the electron-accepting compound are in solution. Thus, the organic compound and the electron-accepting compound are uniformly mixed, and the conductivity of the organic compound layer doped with the electron-accepting compound is isotropic.

  Therefore, in order to control electrical characteristics such as conductivity, the composition ratio between the organic compound and the electron-accepting compound contained in the layer is changed, or the type of the compound contained in the layer is changed. It was necessary to let them.

  On the other hand, when the composition ratio of the layer or the type of compound contained in the layer is changed, characteristics other than electrical characteristics, such as optical characteristics (refractive index, etc.) change. If the optical characteristics change, a change in emission color due to a change in emission spectrum and a change in the efficiency of external extraction of emitted light occur. Therefore, it is difficult to change the electrical characteristics while maintaining the optical characteristics.

In other words, the design of the light-emitting element must be strictly designed in consideration of various characteristics such as electrical characteristics and optical characteristics, and the production of the light-emitting element must be strictly managed as designed. It was.
Japanese Patent Laid-Open No. 11-251067 Japanese Patent Laid-Open No. 2001-244079

  Therefore, an object of the present invention is to provide a light-emitting element and a light-emitting device that are redundant in design and production.

  As a result of intensive studies, the present inventor has found that the problem can be solved by manufacturing a light-emitting element having a layer containing a composite material.

  Therefore, one embodiment of the present invention includes a layer including a light-emitting substance between a pair of electrodes, the layer including a light-emitting substance includes a layer including a composite material, and the layer including a composite material includes an organic compound and an inorganic compound. And a concentration ratio between the organic compound and the inorganic compound is periodically changed.

  Another embodiment of the present invention includes a layer including a light-emitting substance between a pair of electrodes, the layer including a light-emitting substance includes a layer including a composite material, and the layer including a composite material includes an organic compound and an inorganic compound. And the concentration of the inorganic compound is periodically changed.

  In the above structure, the concentration of the inorganic compound is preferably 5 wt% or more and 90 wt% or less. More preferably, it is preferably 10 wt% or more and 80 wt% or less.

  Another embodiment of the present invention includes a layer including a light-emitting substance between a pair of electrodes, the layer including a light-emitting substance includes a layer including a composite material, and the layer including a composite material includes an organic compound and an inorganic compound. And the concentration of the organic compound is periodically changed.

  In the above structure, the concentration of the organic compound is preferably 10 wt% or more and 95 wt%. More preferably, it is 20 wt% or more and 90 wt% or less.

  In the above structure, one period of the periodic change is preferably 0.5 nm or more and 30 nm or less. In particular, the thickness is preferably 1 nm or more and 10 nm or less.

  In the above structure, the layer including the composite material is preferably provided in contact with one of the pair of electrodes. Alternatively, the layer including the composite material may be provided in two layers so as to be in contact with the pair of electrodes.

  In the above structure, the inorganic compound is a transition metal oxide. Specifically, any one or more of titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide can be used.

  In the above structure, the organic compound has a hole transporting property. In particular, an organic compound having an arylamine skeleton or an organic compound having a carbazole skeleton is preferable.

  Another aspect of the present invention includes a layer containing a light-emitting substance between a pair of electrodes, and the layer containing the light-emitting substance has a large average atomic weight and an average atomic weight in an image observed using a transmission electron microscope. The light-emitting element has a layer in which small regions are alternately stacked and a thickness of the stack is not less than 0.5 nm and not more than 30 nm.

  Another aspect of the present invention includes a layer containing a light-emitting substance between a pair of electrodes, and the layer containing the light-emitting substance has a large average atomic weight and an average atomic weight in an image observed using a transmission electron microscope. The light-emitting element has a layer in which small regions are alternately stacked and a thickness of the stack is not less than 1 nm and not more than 10 nm.

  Another embodiment of the present invention includes a layer including a light-emitting substance between a pair of electrodes, and the layer including a light-emitting substance is a dark region and a light region in an image observed using a transmission electron microscope. And a layer having a stack thickness of 0.5 nm or more and 30 nm or less.

  Another embodiment of the present invention includes a layer including a light-emitting substance between a pair of electrodes, and the layer including a light-emitting substance is a dark region and a light region in an image observed using a transmission electron microscope. And a layer having a stack thickness of 1 nm or more and 10 nm or less.

  In the above structure, the layer containing a light-emitting substance contains an organic compound and an inorganic compound.

  The present invention also includes a light emitting device having the above-described light emitting element. The light-emitting device in this specification includes a light-emitting element and a control unit that controls light emission of the light-emitting element. Specifically, an image display device or a light source (including a lighting device) is included. 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.

  The light-emitting element of the present invention can change the electrical characteristics of a layer containing a composite material, in particular, conductivity without changing the composition ratio or the type of compound. Therefore, other characteristics such as optical characteristics do not change much. Therefore, redundancy can be provided in the manufacture of the light-emitting element and the light-emitting device.

  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.

(Embodiment 1)
In this embodiment mode, a layer containing a composite material included in the light-emitting element of the present invention will be described.

  The layer including the composite material includes an organic compound and an inorganic compound, and the concentration ratio between the organic compound and the inorganic compound changes periodically. When the concentration ratio between the organic compound and the inorganic compound is periodically changed, the conductivity in the stacking direction (also referred to as the film thickness direction) can be controlled. In this specification, the stacking direction refers to a direction from one electrode to the other electrode of electrodes provided on both sides of a layer containing a composite material.

  By changing the length of the periodic change in the concentration ratio between the organic compound and the inorganic compound, a layer having a desired conductivity can be obtained. For example, the conductivity in the stacking direction (film thickness direction) can be increased by shortening one cycle of the periodic change in the concentration ratio, and by increasing the cycle, the conductivity in the stacking direction can be increased. The conductivity can be lowered. In this specification, the term “periodic change” refers to a change in the stacking direction such that the maximum value and the minimum value of the concentration are alternately repeated. It should be noted that the repeated period of the periodic change does not have to be exactly the same, and the repeated amplitude of the periodic change need not be exactly the same.

  In addition, since the organic compound and the inorganic compound included in the layer including the composite material are insulators, the conductivity as the insulator is generally obtained in the plane direction of the layer including the composite material. Therefore, a desired conductivity can be obtained in the direction in which the concentration ratio changes periodically (stacking direction, film thickness direction), and the direction in which the concentration ratio does not change periodically (plane direction). Since the conductivity with respect to becomes a certain value, anisotropy occurs in the conductivity.

  The organic compound contained in the layer containing the composite material is preferably a material excellent in hole transportability. An organic material having an arylamine skeleton is particularly preferable. For example, 4,4′-bis (N- (4-N, N-di-m-tolylamino) phenyl) -N-phenylamino) biphenyl (abbreviation: DNTPD ), 4,4′-bis [N- (4-diphenylaminophenyl) -N-phenylamino] biphenyl (abbreviation: DPAB), N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (abbreviation: TPD), 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: α-NPD), 4 , 4′-bis [N- (9,9-dimethylfluoren-2-yl) -N-phenylamino] biphenyl (abbreviation: DFLDPBi), 4,4′-bis [N- (4-biphenylyl) -N— Fe Ruamino] biphenyl (abbreviation: BBPB), 1,5-bis (diphenylamino) naphthalene (abbreviation: DPAN), 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA) ), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA) (ie, benzene ring-nitrogen bond) Can be used. Alternatively, an organic material having a carbazole skeleton is preferably used. For example, N- (2-naphthyl) carbazole (abbreviation: NCz), 4,4′-di (N-carbazolyl) biphenyl (abbreviation: CBP), 10-bis [4- (N-carbazolyl) phenyl] anthracene (abbreviation: BCPA), 3,5-bis [4- (N-carbazolyl) phenyl] biphenyl (abbreviation: BCPPi), 1,3,5-tris [ A compound such as 4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB) can be used. Note that other than these substances, any substance that has a property of transporting more holes than electrons may be used.

  The inorganic compound contained in the layer containing the composite material is preferably a transition metal oxide, specifically, titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide. , Tungsten oxide, manganese oxide, rhenium oxide, and the like. In particular, vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide are preferable because of their high electron-accepting properties. Among these, molybdenum oxide is particularly preferable because it is stable in the air and easy to handle.

  Note that the layer containing the composite material included in the light-emitting element of the present invention can be manufactured by an evaporation method. Molybdenum oxide is easy to evaporate in a vacuum and is preferable from the viewpoint of the manufacturing process.

  The layer containing the composite material included in the light-emitting element of the present invention can be manufactured by a co-evaporation method of an organic compound and an inorganic compound. By periodically changing the concentration ratio between the organic compound and the inorganic compound, the conductivity in the stacking direction (film thickness direction) can be controlled.

  As a method for periodically changing the concentration ratio between the organic compound and the inorganic compound, it is possible to relatively rotate the substrate, the evaporation source, and the mask.

  For example, by fixing the evaporation source containing the organic compound and the evaporation source containing the inorganic compound at a distance and rotating the substrate (rotating the substrate), the concentration ratio of the organic compound and the inorganic compound is periodically changed. It is possible to change. The length of one cycle can be changed by controlling the deposition rate and the rotation rate.

  In this case, when the rotation speed of the substrate is slowed, one cycle of the change in the concentration ratio between the organic compound and the inorganic compound becomes longer, and the conductivity in the stacking direction becomes smaller.

  In addition, by making the rotation speed of the substrate constant and increasing the deposition rate from the evaporation source, one cycle of the change in the concentration ratio between the organic compound and the inorganic compound can be lengthened.

  Also, the evaporation source containing the organic compound and the evaporation source containing the inorganic compound are fixed at a distance, and the substrate is moved while rotating (the substrate is revolved), so that the concentration ratio between the organic compound and the inorganic compound can be adjusted. It is possible to change periodically. In this case, one cycle of the periodic change can be lengthened by slowing the revolution of the substrate.

  Further, the substrate may be rotated by combining rotation and revolution. In this case as well, the length of one cycle can be changed by controlling the vapor deposition rate and the rotation speed of the substrate.

  It is also possible to periodically change the concentration ratio between the organic compound and the inorganic compound by fixing the evaporation source and the substrate and rotating the mask. For example, one cycle of the density ratio can be shortened by speeding up the rotation of the mask. Thereby, a layer having high conductivity in the stacking direction can be obtained.

  It is also possible to periodically change the concentration ratio between the organic compound and the inorganic compound by fixing the substrate and rotating the evaporation source.

  Further, the concentration ratio of the organic compound and the inorganic compound may be periodically changed by opening and closing the shutter while the evaporation source and the substrate are fixed.

  Further, the concentration ratio between the organic compound and the inorganic compound may be periodically changed by changing the adsorption speed by changing the temperature of the substrate. That is, by increasing or decreasing the temperature of the substrate, the adsorption rate may be changed, and the concentration ratio between the organic compound and the inorganic compound may be changed.

  Note that one period of the periodic change changes depending on the distance between the substrate and the evaporation source, the distance between the evaporation source and the evaporation source, etc., in addition to the rotation speed of the substrate and the evaporation speed. Just design.

  By using the above method, a layer in which the concentration ratio between the organic compound and the inorganic compound is periodically changed, that is, a layer containing the composite material of the present invention can be formed. An example of the concentration distribution in the depth direction of the layer containing the composite material of the present invention is shown in FIG. As shown in FIG. 18, the concentration of the organic compound and the concentration of the inorganic compound periodically change in the depth direction (stacking direction, film thickness direction), thereby causing anisotropy in the conductivity. The concentration of the inorganic compound is preferably 5 wt% or more and 90 wt% or less, and more preferably 10 wt% or more and 80 wt% or less. The concentration of the organic compound is preferably 10 wt% or more and 95 wt% or less, and more preferably 20 wt% or more and 90 wt% or less.

  In addition, one period of the periodic change of the concentration ratio is preferably 0.5 nm or more and 30 nm or less. More preferably, it is 1 nm or more and 10 nm or less.

  The layer containing the composite material of the present invention can obtain a layer having a desired conductivity with respect to the stacking direction by changing the length of one cycle of the periodic change. In addition, since the organic compound and the inorganic compound included in the layer including the composite material are insulators, the conductivity as the insulator is generally obtained in the plane direction of the layer including the composite material, and the conductivity is constant. It is. That is, a desired conductivity can be obtained in the direction in which the concentration ratio changes periodically (stacking direction), and the conductivity in the direction in which the concentration ratio does not change periodically (plane direction) is Since it has a certain value, anisotropy occurs in the conductivity.

  Therefore, unlike a layer in which an organic compound and an inorganic compound are simply mixed, the conductivity of a layer including a composite material can be made anisotropic.

  Further, unlike the case where a layer made of only an organic compound and a layer made of only an inorganic compound are stacked, crystallization can be suppressed by mixing the organic compound and the inorganic compound.

  In addition, the layer including the composite material can change the electrical characteristics without changing the composition ratio of the organic compound and the inorganic compound included in the layer or the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to design and manufacture of a light emitting element.

(Embodiment 2)
A vapor deposition apparatus used for carrying out the present invention and a method for forming a layer containing a composite material using the vapor deposition apparatus will be described with reference to FIGS.

  In the vapor deposition apparatus used for carrying out the present invention, a transfer chamber 1002 is provided in addition to a treatment chamber 1001 for performing a vapor deposition process on a workpiece. The object to be processed is transferred to the processing chamber 1001 through the transfer chamber 1002. The transfer chamber 1002 is provided with an arm 1003 for transferring an object to be processed (FIG. 23).

  In the processing chamber 1001, as shown in FIG. 20, a holding unit for holding an object to be processed, an evaporation source 1011a holding a first material, and an evaporation source 1011b holding a second material. Is provided. In FIG. 20, the holding unit for holding the object to be processed includes a first rotating plate 1012 that rotates about a shaft 1013 and a plurality of second rotating plates 1014 a provided on the first rotating plate 1012. To 1014d. The second rotating plates 1014a to 1014d rotate independently of each other around the shafts provided for the second rotating plates 1014a to 1014d, separately from the shaft 1013. The objects to be processed 1015a to 1015d are held on the second rotating plates 1014a to 1014d, respectively.

  In FIG. 20, the workpiece 1015a is held on the second rotating plate 1014a, the workpiece 1015b is held on the second rotating plate 1014b, and the workpiece 1015c is held on the second rotating plate 1014c. The workpiece 1015d is held on the second rotating plate 1014d.

The layer containing the composite material is formed as follows. First, the material held in the evaporation sources 1011a and 1011b is heated and sublimated. Further, the first rotating plate 1012 and the second rotating plates 1014a to 1014d holding the object to be processed are rotated. As shown in FIG. 20, when the distance between the object to be processed 1015a and the evaporation source 1011a is shorter than the distance between the object to be processed 1015a and the evaporation source 1011b, Each material is deposited such that the concentration of the first material is higher than the concentration of the material. On the other hand, when the distance between the object to be processed 1015c and the evaporation source 1011b is shorter than the distance between the object to be processed 1015c and the evaporation source 1011a like the object to be processed 1015c, Each material is deposited so that the concentration of the second material is higher than the concentration of the first material.
Next, the rotation of the first rotating plate 1012 changes the position of the second rotating plate 1014a in the processing chamber 1001, and the workpiece 1015a is held at the position of the second rotating plate 1014c in FIG. When the distance between the object to be processed 1015a and the evaporation source 1011b is closer than the distance between the object to be processed 1015a and the evaporation source 1011a, the concentration of the second material on the object to be processed 1015a is higher than the concentration of the first material. Each material is vapor-deposited so as to be high.

  As described above, by changing the positions of the objects to be processed 1015a to 1015d with respect to the evaporation sources 1011a and 1011b, the composite material having a plurality of regions having different concentration ratios of the contained materials on the objects to be processed 1015a to 1015d. A layer containing can be formed. Here, the width in the stacking direction (film thickness direction) of each region included in the layer containing the composite material (the length of one cycle of the periodic change in the concentration ratio) is determined by the rotational speed of the first rotating plate 1012 or the like. What is necessary is just to change suitably by adjusting.

  For example, when the rotation of the first rotating plate 1012 is made faster, one cycle of the change in the concentration ratio between the first material and the second material is shortened, and the conductivity in the stacking direction is increased.

  In addition, by making the rotation speed of the first rotating plate 1012 constant and increasing the evaporation speed from the evaporation source 1011a and the evaporation source 1011b, one cycle of the change in the concentration ratio between the first material and the second material can be obtained. It can be lengthened.

  The shapes of the first rotating plate 1012 and the second rotating plates 1014a to 1014d are not particularly limited, and may be a polygon such as a rectangle in addition to a circle as shown in FIG. In addition, the second rotating plates 1014a to 1014d are not necessarily provided, but by providing the second rotating plates 1014a to 1014d, in-plane variations such as the thickness of a layer formed on the object to be processed are provided. Can be reduced.

  The configuration in the processing chamber 1001 is not limited to that shown in FIG. 20, and for example, a configuration in which the position of the evaporation source shown in FIG. 21 is changed may be used.

  In FIG. 21, evaporation sources 1021a and 1021b are fixed, and a rotating plate 1026 that rotates about a shaft 1027 and a holding portion 1022 for holding an object to be processed are provided to face each other. Further, the objects to be processed 1025a to 1025d are held in the holding unit 1022. The evaporation source 1021a holds a first material, and the evaporation source 1021b holds a second material. When each evaporation source is positioned so that the evaporation source 1021a is closer to the object to be processed 1025a than the evaporation source 1021b, the concentration on the object to be processed 1025a is higher than the concentration of the second material. Each material is deposited so that the concentration of one material is higher. Further, if the rotating plate 1026 rotates and the evaporation source 1021b is positioned closer to the object to be processed 1025a than the evaporation source 1021a, the concentration of the first material is higher on the object to be processed 1025a. Each material is deposited so that the concentration of the second material is higher. Thus, the vapor deposition apparatus may have a configuration in which the position of the evaporation source with respect to the object to be processed is changed by changing the position of the evaporation source. That is, it is only necessary that the evaporation source and the object to be processed are provided so that their positions change relatively.

In the case of the configuration of FIG. 21, when the rotation of the evaporation source 1021a and the evaporation source 1021b is made faster, the length of one cycle of the periodic change in the concentration ratio of the first material and the second material becomes shorter. The overall conductivity increases.

  In addition to the configurations shown in FIGS. 20 and 21, as shown in FIG. 22, a rotating plate that functions as a mask between the evaporation source and the holding unit and has an opening is provided. The configuration may be such that the position of the opening of the rotating plate changes.

  In FIG. 22, the evaporation source 1031a holding the first material and the evaporation source 1031b holding the second material are sandwiched between the holding unit 1032 and the rotating plate 1038 provided with the opening 1040, respectively. It is provided so as to face each other. The rotating plate 1038 rotates about the shaft 1039, and the position of the opening 1040 changes by rotating. When the opening 1040 is positioned closer to the evaporation source 1031a than the evaporation source 1031b, the concentration of the first material is higher from the opening 1040 toward the holding unit 1032. The gas is diffused in a higher state, and each material is deposited on the object to be processed 1035 held in the holding portion 1032 so that the concentration of the first material is higher than the concentration of the second material. The In addition, if the rotating plate 1038 rotates and the opening 1040 is positioned closer to the evaporation source 1031b than the evaporation source 1031a (for example, as illustrated by the dotted line 1041), the second material Each material is deposited on the object to be processed 1035 so that the concentration is higher than the concentration of the first material.

In the case of the configuration shown in FIG. 22, when the rotation of the rotating plate 1038 is accelerated, one cycle of the change in the concentration ratio between the first material and the second material is shortened, and the conductivity in the stacking direction is increased.

  As described above, the layer containing the composite material can be formed by relatively changing the positions of the evaporation source and the object to be processed. In addition to the evaporation source, the layer containing the composite material can be formed by relatively changing the position of the opening provided in the rotating plate functioning as a mask.

  Note that the configuration of the vapor deposition apparatus is not limited to that illustrated in FIG. 23, and may be, for example, a configuration in which a sealing chamber for sealing the light emitting element is further provided. Further, the number of processing chambers for vapor deposition is not limited to one, and two or more chambers may be provided.

(Embodiment 3)
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 embodiment of a light-emitting element of the present invention is 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, tungsten oxide is 0 In addition to indium oxide (IWZO) containing 5 to 5 wt% and zinc oxide 0.1 to 1 wt%, 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 metal nitride (TiN) , It can be used.

  The first layer 103 is a layer including the composite material described in Embodiment 1. The layer includes an organic compound and an inorganic compound, and the concentration ratio between the organic compound and the inorganic compound is periodically changed.

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′—. Diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (abbreviation: TPD), 4,4 ′, 4 ″ -tris (N, N-diphenyl) Aromatic amines such as amino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA) That is, it is a layer made of a compound (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 ), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), and the like, which are freely combined with a substance having a high carrier transport property and 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 (4-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 -(4-tert-Butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-biphenylyl) -4-phenyl-5- (4- tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-biphenylyl) -4- (4-ethylphenyl) -5- (4-tert-butylphenyl) -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 (MgAg, AlLi) containing these. 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 compound or an alkaline earth metal compound such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), or the like is used. Can be used. 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.

  Further, as a method for forming the second layer 104, the third layer 105, and the fourth layer 106, a known method such as an inkjet method or a spin coating method may be used in addition to the vapor deposition method. 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 formed using a light-transmitting substance, light emission is extracted from the substrate side through the first electrode 102 as illustrated in FIG. In the case where only the second electrode 107 is formed using a light-transmitting substance, light emission is extracted from the side opposite to the substrate through the second electrode 107 as illustrated in FIG. In the case where both the first electrode 102 and the second electrode 107 are made of a light-transmitting substance, light is emitted from the first electrode 102 and the second electrode 107 as shown in FIG. 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. As long as it has a layer including the composite material described in Embodiment Mode 1, other than the above may be used.

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 composite 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 conductive substance, a fourth layer 306 which is a layer containing the composite material of the present invention, and a second electrode 307 functioning as an anode are stacked in this order. 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. By manufacturing a plurality of such light-emitting elements over one substrate, a passive matrix light-emitting device can be manufactured. In addition to a substrate made of glass, plastic, or the like, a light emitting element may be manufactured on a thin film transistor (TFT) array substrate, for example. 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. 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.

  A light-emitting element of the present invention includes a layer containing the composite material described in Embodiment Mode 1. Therefore, the electrical characteristics of the layer containing the composite material can be changed by changing the length of one cycle of the periodic change in the concentration ratio between the organic compound and the inorganic compound contained in the layer containing the composite material. Is possible. That is, the electrical characteristics can be changed without changing the composition ratio between the organic compound and the inorganic compound contained in the layer and the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to design and manufacture of a light emitting element.

  In addition, the layer including the composite material of the present invention has high conductivity in the stacking direction, so that low voltage driving of the light emitting element can be realized. In addition, the electrical conductivity is low with respect to the surface direction, and the occurrence of crosstalk between adjacent light emitting elements can be suppressed.

  In addition, since the layer including the composite material used in the present invention has high conductivity in the stacking direction, the increase in the driving voltage of the light-emitting element can be suppressed even when the layer including the composite material is thickened. it can.

  In addition, since the layer including the composite material can be formed with a desired thickness, it is possible to improve color purity and improve light extraction efficiency by optical design without increasing the driving voltage of the light-emitting element. it can.

  Further, by increasing the thickness of the layer containing the composite 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 composite material is 100 to 500 nm, preferably 200 to 500 nm. It can be.

  In addition, the layer containing the composite 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 4)
In this embodiment, a light-emitting element having a structure different from that described in Embodiment 3 will be described with reference to FIGS. In the structure described in this embodiment mode, a layer containing the composite material of the present invention can be provided so as to be in contact with an electrode functioning as a cathode.

  FIG. 5A 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 3 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 composite 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 this configuration, as shown in FIG. 5A, by applying a voltage, electrons are exchanged near the interface between the second layer 412 and the third layer 413, and the electrons and 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.

  Further, the third layer 413 has high conductivity in the stacking direction and low conductivity in the plane direction. Thus, the driving voltage of the light emitting element can be reduced. In addition, occurrence of crosstalk between adjacent light emitting elements can be suppressed. In addition, when the third layer 413 is thickened, an increase in driving voltage of the light-emitting element can be suppressed.

  In addition, even when the third layer 413 is thickened, an increase in driving voltage of the light-emitting element can be suppressed; therefore, the thickness of the third layer 413 can be freely set, and Luminous extraction 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.

  Further, by increasing the thickness of the third layer 413, a short circuit due to dust, impact, or the like can be prevented.

Further, taking FIG. 5A as an example, when the second electrode 402 is formed by sputtering, damage to the first layer 411 containing a light-emitting substance can be reduced.

  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. 5 (b), FIG. 5 (c) and FIG. In FIG. 5B, FIG. 5C, and FIG. 6, the reference numerals in FIG. Reference numeral 400 denotes a substrate carrying the light emitting element of the present invention.

  FIG. 5 shows 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 transmissive 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. 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. 6 shows 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. . In addition, the first electrode 401 is made light transmissive 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. 6B. 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. Configuration is also possible.

  Note that in the case of manufacturing the light-emitting element in this embodiment, a known method can be used regardless of a wet method or a dry method. Note that the layer including the composite material is preferably formed by the method described in Embodiments 1 and 2.

  Further, as illustrated in FIG. 5, 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. 6, 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.

  A light-emitting element of the present invention includes a layer containing the composite material described in Embodiment Mode 1. Therefore, the electrical characteristics of the layer containing the composite material can be changed by changing the length of one cycle of the periodic change in the concentration ratio between the organic compound and the inorganic compound contained in the layer containing the composite material. Is possible. That is, the electrical characteristics can be changed without changing the composition ratio between the organic compound and the inorganic compound contained in the layer and the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to design and manufacture of a light emitting element.

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

(Embodiment 5)
In this embodiment, a light-emitting element having a structure different from the structures described in Embodiments 3 and 4 will be described with reference to FIGS. In the structure described in this embodiment, a layer containing a composite material 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 3. The first layer 211 is a layer including the composite material described in Embodiment 1, and the second layer 212 is a layer including 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-transport property, and the fourth layer 214 is a layer including the composite material described in Embodiment 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.

  The first layer 211 and the fourth layer 214 have high conductivity in the stacking direction and low conductivity in the plane direction. Thus, the driving voltage of the light emitting element can be reduced. In addition, occurrence of crosstalk between adjacent light emitting elements can be suppressed. In addition, when the first layer 211 and the fourth layer 214 are thickened, an increase in driving voltage of the light-emitting element can be suppressed.

  In addition, even when the first layer 211 and the fourth layer 214 are thickened, an increase in driving voltage of the light-emitting element can be suppressed; therefore, the thicknesses of the first layer 211 and the fourth layer 214 can be reduced. It can be set freely, and the light extraction efficiency 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.

In addition, the light emitting element of this embodiment can make the anode side and the cathode side of the second layer responsible for the light emitting function very thick, and can effectively prevent a short circuit of the light emitting element. Further, taking FIG. 3A as an example, when the second electrode 202 is formed by sputtering, damage to the second layer 212 containing a light-emitting substance can be reduced. Furthermore, by configuring the first layer 211 and the fourth layer 214 with the same material, layers composed of the same material can be provided on both sides of the layer responsible for the light emitting function, thereby suppressing stress strain. 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 composite material described in Embodiment 1, and the fourth layer 214 includes one compound selected from 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, a known method can be used regardless of a wet method or a dry method. Note that the layer including the composite material is preferably formed by the method described in Embodiments 1 and 2.

  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 201.

  A light-emitting element of the present invention includes a layer containing the composite material described in Embodiment Mode 1. Therefore, the electrical characteristics of the layer containing the composite material can be changed by changing the length of one cycle of the periodic change in the concentration ratio between the organic compound and the inorganic compound contained in the layer containing the composite material. Is possible. That is, the electrical characteristics can be changed without changing the composition ratio between the organic compound and the inorganic compound contained in the layer and the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to design and manufacture of a light emitting element.

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

(Embodiment 6)
In this embodiment, a light-emitting element having a structure different from the structures shown in Embodiments 3 to 5 will be described. The structure described in this embodiment is a structure in which the composite material of the present invention is applied as a charge generation layer of a light-emitting element having a structure in which a plurality of light-emitting units are stacked.

  In this embodiment, a light-emitting element having a structure in which a plurality of light-emitting units are stacked (hereinafter referred to as a tandem element) will be described. That is, the light-emitting element has a plurality of light-emitting units between the first electrode and the second electrode. FIG. 19 shows a tandem element in which two light emitting units are stacked.

  In FIG. 19, a first light emitting unit 511 and a second light emitting unit 512 are stacked between a first electrode 501 and a second electrode 502. A charge generation layer 513 is formed between the first light emitting unit 511 and the second light emitting unit 512.

  A known material can be used for the first electrode 501 and the second electrode 502.

  The first light-emitting unit 511 and the second light-emitting unit 512 can each have a known configuration.

  The charge generation layer 513 includes the layer containing the composite material described in Embodiment 1. The layer including the composite material has high conductivity in the stacking direction. Thus, the driving voltage of the light emitting element can be reduced. In addition, the layer including the composite material has low conductivity in the surface direction. Therefore, occurrence of crosstalk between adjacent light emitting elements can be suppressed.

  Note that the charge generation layer 513 may be formed by combining a layer containing a composite material and a known material. For example, as shown in Embodiment Mode 4, a layer including a composite material and a layer including one compound selected from electron-donating substances and a compound having a high electron-transport property are combined. Also good. Alternatively, a layer containing a composite material and a transparent conductive film may be combined.

  Although this embodiment mode describes a light-emitting element having two light-emitting units, similarly, the layer including the composite material described in Embodiment Mode 1 is applied to a light-emitting element in which three or more light-emitting units are stacked. Is possible. For example, a light emitting element in which three light emitting units are stacked is stacked in the order of a first light emitting unit, a first charge generating layer, a second light emitting unit, a second charge generating layer, and a third light emitting unit. However, the layer including the composite material described in Embodiment 1 may be included in only one of the charge generation layers, or may be included in all of the charge generation layers.

  A light-emitting element of the present invention includes a layer containing the composite material described in Embodiment Mode 1. Therefore, the electrical characteristics of the layer containing the composite material can be changed by changing the length of one cycle of the periodic change in the concentration ratio between the organic compound and the inorganic compound contained in the layer containing the composite material. Is possible. That is, the electrical characteristics can be changed without changing the composition ratio between the organic compound and the inorganic compound contained in the layer and the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to design and manufacture of a light emitting element.

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

(Embodiment 7)
In this embodiment mode, optical design of a light-emitting element will be described.

In the light-emitting elements described in any of Embodiments 3 to 6, at least one of the thicknesses of each layer excluding the first electrode and the second electrode is different for each light-emitting element that emits each emission color. Thus, the light extraction efficiency for each emission color can be increased.

For example, as illustrated in FIG. 10, a light emitting element that emits red color (R), green color (G), and blue color (B) includes a first electrode 1101 that is a reflective electrode, and a light-transmitting property. And the second layer 1101R, 1111G, 1111B, the second layer 1112R, 1112G, 1112B, the third layer 1113R, 1113G, 1113B, the fourth layer 1114R, 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 thickness of the first layer 1111R, 1111G, 1111B different for each luminescent color, it is reflected directly through the second electrode and reflected by the first electrode. It is possible to prevent a decrease in light extraction efficiency due to a difference in optical path between the case where recognition is performed through the second 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 of the emission wavelength, When the ratio is 3/4, 5/4,..., The light extraction efficiency 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 including the composite 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 layer including the composite material described in Embodiment Mode 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. Moreover, as shown in FIG. 10, the value of m of (2m−1) / 4 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, the film thicknesses of at least the first layer to the fourth layer 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. Further, the layer that needs to be thicker is preferably a layer containing the composite material described 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 5, it can be combined as appropriate with any of the other embodiment modes.

(Embodiment 8)
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. 7A is a top view illustrating the light-emitting device, and FIG. 7B is a cross-sectional view taken along lines A-A ′ and B-B ′ in FIG. 7A. 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 will be 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 driving circuit may be formed of a known CMOS circuit, PMOS circuit, or NMOS circuit. In this embodiment mode, an integrated type of a driver and a pixel portion in which a driver circuit is formed over a substrate is shown; however, this is not necessarily required, and the driver circuit 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 addition, a curved surface having a curvature is formed at the upper end portion or the lower end portion 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 resist that becomes insoluble in an etchant by light irradiation or a positive resist that becomes soluble in an etchant by light irradiation can be used.

  Over the first electrode 613, a layer 616 containing a light-emitting substance and a 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 616 containing a light-emitting substance includes the layer containing the composite material described in Embodiment 1. In addition, the other material forming the layer 616 containing a light-emitting substance may be a low molecular material, a medium molecular material (including an oligomer or a dendrimer), or a high molecular material. In addition, as a material used for a layer containing a light-emitting substance, an organic compound is usually used in a single layer or a stacked layer. I will do it. The layer 616 containing a light-emitting substance is formed by a known method such as an evaporation method using an evaporation mask, an inkjet method, or a spin coating method. Note that the layer including the composite material is preferably formed by the method described in Embodiments 1 and 2.

Further, as a material used for the second electrode 617 formed over the light-emitting substance-containing layer 616 and functioning as a cathode, a material having a low work function (Al, Ag, Li, Ca, or an alloy or compound thereof, MgAg, or the like) MgIn, AlLi, CaF ₂ , LiF, or calcium nitride) is preferably used. Note that in the case where light generated in the layer 616 containing a light-emitting substance passes through the second electrode 617, the second electrode 617 includes a thin metal film and a transparent conductive film (ITO, 2 to 20 wt. % Of indium oxide containing zinc oxide, 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 is filled with a filler, and may be filled with a sealant 605 in addition to an inert gas (such as nitrogen or argon).

  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 includes the layer containing the composite material described in Embodiment Mode 1. Therefore, the electrical characteristics of the layer containing the composite material can be changed by changing the length of one cycle of the periodic change in the concentration ratio between the organic compound and the inorganic compound contained in the layer containing the composite material. Is possible. That is, the electrical characteristics can be changed without changing the composition ratio of the compound contained in the layer or the type of the compound. Therefore, the electrical characteristics such as the optical characteristics are not changed much. Therefore, redundancy can be given to the design and manufacture of the light emitting device.

  In addition, since the light-emitting device of the present invention includes the layer containing the composite material described in Embodiment Mode 1, the conductivity is low in the plane direction and the stacking direction is higher than the plane direction. Also, the conductivity can be increased. Therefore, low voltage driving of the light emitting element can be realized while suppressing the occurrence of crosstalk between adjacent light emitting elements.

  In addition, since the layer including the composite material described in Embodiment 1 has high conductivity in the stacking direction, an increase in driving voltage of the light-emitting element is suppressed even when the layer including the composite material is thickened. can do. Therefore, the layer containing the composite material can be thickened to prevent a short circuit of the light-emitting element. In addition, a light-emitting device with reduced power consumption can be obtained.

  In addition, since the layer including the composite material can be formed with a desired thickness, it is possible to improve color purity and improve light extraction efficiency by optical design without increasing the driving voltage of the light-emitting element. it can. 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 matrix light emitting device may be used. FIG. 8 is a perspective view of a passive matrix light-emitting device manufactured by applying the present invention. In FIG. 8, a layer 955 containing a light-emitting substance is provided between the electrode 952 and the electrode 956 over the 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 matrix 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 drive voltage.

(Embodiment 9)
In this embodiment mode, an electric device of the present invention including the light-emitting device described in Embodiment Mode 8 as a part thereof will be described. An electric device of the present invention includes a layer including the composite material described in Embodiment 1 and includes a display portion with low power consumption. In addition, a highly reliable display portion in which a short circuit due to dust, impact, or the like is suppressed is provided.

As an electric device manufactured using the light-emitting device of the present invention, a camera such as a video camera or a digital camera, a goggle-type display, a navigation system, a sound reproduction device (car audio, audio component, etc.), a computer, a game device, and portable information Plays back a recording medium such as a terminal (mobile computer, mobile phone, portable game machine, electronic book, etc.) and recording medium (specifically, Digital Versatile Disc (DVD)) and displays the image. And a display device). Specific examples of these electric devices are shown in FIGS.
FIG. 9A 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 3 to 7 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high, the driving voltage is low, and a short circuit due to dust, impact, or the like can be prevented. Further, it has a feature that generation of crosstalk between adjacent elements is suppressed. 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. 9B 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 3 to 7 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high, the driving voltage is low, and a short circuit due to dust, impact, or the like can be prevented. Further, it has a feature that generation of crosstalk between adjacent elements is suppressed. 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 the 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. 9C 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 configured by arranging light-emitting elements similar to those described in Embodiment Modes 3 to 7 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high, the driving voltage is low, and a short circuit due to dust, impact, or the like can be prevented. Further, it has a feature that generation of crosstalk between adjacent elements is suppressed. 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. 9D 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 Embodiment Modes 3 to 7 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high, the driving voltage is low, and a short circuit due to dust, impact, or the like can be prevented. Further, it has a feature that generation of crosstalk between adjacent elements is suppressed. 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. 9E 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 3 to 7 in a matrix. The light-emitting element has a feature that the efficiency of extracting light to the outside is high, the driving voltage is low, and a short circuit due to dust, impact, or the like can be prevented. Further, it has a feature that generation of crosstalk between adjacent elements is suppressed. 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.

  As described above, the applicable range of the light-emitting device of the present invention is so wide that the light-emitting device can be applied to electric appliances in various fields. By using the light-emitting device of the present invention, an electric device having a display portion with low power consumption and high reliability can be provided.

  In this example, a layer containing a composite material will be specifically described.

  Indium tin oxide containing silicon was formed on the substrate. On top of that, a layer in which DNTPD and molybdenum oxide were co-deposited was formed to a thickness of 120 nm so that the weight ratio of DNTPD to molybdenum oxide in the entire layer was 1: 0.67.

  Then, 200 nm of aluminum was formed on the layer on which DNTPD and molybdenum oxide were co-evaporated, and the device characteristics were examined.

  An element in which a layer containing DNTPD and molybdenum oxide was formed with an organic compound deposition rate of 0.4 nm / s, a substrate rotation (revolution) speed of 8 rpm, and an organic compound deposition rate of 0.4 nm / s. The number of rotations (revolutions) of the substrate is 2 rpm, the element on which the layer containing DNTPD and molybdenum oxide is formed is element 2, the vapor deposition rate of the organic compound is 1.6 nm / s, and the number of rotations (revolutions) of the substrate is 8 rpm. An element in which a layer containing DNTPD and molybdenum oxide was formed as element 3. The current density-voltage characteristics of the elements 1 to 3 are shown in FIG.

  As can be seen from FIG. 11, the element 1 is more likely to flow current in the direction between the electrodes (stacking direction) than the element 2 or element 3.

  Moreover, the cross section of the element 1-the element 3 was observed using the transmission electron microscope (Transmission Electron Microscope). Images (TEM images) obtained by observation are shown in FIGS. FIG. 12 is an image (magnification: 150,000 times) obtained by observing the element 1, FIG. 13 is an image (magnification: 1 million times) obtained by observing the element 1, and FIG. 15 is an image (magnification: 150,000 times) obtained by observing 2, FIG. 15 is an image (magnification: 1 million times) obtained by observing element 2, and FIG. FIG. 17 shows an image (magnification: 1 million times) obtained by observing the element 3.

  From FIG. 12 to FIG. 17, it can be seen that the first dark regions and the second light regions are alternately present. The dark first region is a region having a high average atomic weight, and the light second region is a portion having a small average atomic weight. Since the inorganic compound contained in the layer containing the composite material of the present invention has a larger atomic weight than the organic compound, the dark first region in the TEM image is a region containing a large amount of the inorganic compound, and the second lighter color. The region is a region containing a lot of organic compounds.

In the present embodiment, the dark first region is a region having a high molybdenum oxide concentration, and the light second region is a region having a high DNTPD concentration. Therefore, it was found that in the element manufactured in this example, regions having a high concentration of molybdenum oxide and regions having a low concentration of molybdenum oxide exist alternately.

Moreover, the arrows shown in FIGS. 13, 15, and 17 indicate one cycle of the periodic change in the concentration ratio of DNTPD and molybdenum oxide. In the element 1, one period of the periodic change of the concentration ratio was about 3 nm. Further, in the element 2 and the element 3, the periodic change in the concentration ratio was about 12 nm.

Therefore, it can be seen that the element 1 repeats a region in which the concentration of molybdenum oxide is high and a region in which the concentration of molybdenum oxide is low, in an extremely shorter period than the elements 2 and 3. This indicates that one cycle of the periodic change in the concentration ratio between DNTPD and molybdenum oxide is increased by increasing the deposition rate or slowing the substrate rotation speed.

  Further, from the observation results with the transmission electron microscope of FIGS. 12 to 17 and the current density-voltage characteristics of FIG. 11, by shortening the period of the periodic change in the concentration ratio of DNTPD and molybdenum oxide, It can be seen that the current easily flows and the conductivity is improved. Therefore, a layer having a desired conductivity can be formed by controlling a periodic change in the concentration ratio between the organic compound and the inorganic compound.

In this example, the cross section of the element was observed using a transmission electron microscope. However, the element can be observed as long as it is a means for detecting a difference in electron density or average atomic weight.

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 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. 6A and 6B illustrate an electric appliance using a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting element of the present invention. The figure which shows the current density-voltage characteristic of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows the transmission electron microscope observation result of the layer containing a composite material. The figure which shows an example of density | concentration distribution of the layer containing a composite material. 4A and 4B illustrate a light-emitting element of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting element of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting element of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting element of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting element of the present invention.

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 Second electrode 511 First light emitting unit 512 Second light emitting unit 513 Charge generation layer 601 Source side Drive 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 Layer containing light emitting substance 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 Layer containing luminescent material 956 Electrode 1001 Processing chamber 1002 Transfer chamber 1003 Arm 1012 Rotating plate 1013 Shaft 1022 Holding portion 1026 Rotating plate 1027 Shaft 1032 Holding portion 1035 Processed object 1038 Rotating plate 1039 Axis 1040 Opening 1041 Dotted line 1101 1st electrode 1102 2nd electrode 1111 1st layer 1112 2nd layer 1113 3rd layer 1114 4th layer 9101 Housing 9102 Support base 9103 Display 9104 Speaker 9105 Video Input terminal 9201 Main body 9202 Case 9203 Display portion 9204 Keyboard 9205 External connection port 9206 Pointing mouse 9301 Main body 9302 Display portion 9303 Arm portion 9401 Main body 9402 Case 9403 Display portion 9404 Voice 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 reception unit 9506 Image receiving unit 9507 Battery 9508 Audio input unit 9509 Operation key 9510 Eyepiece 1011a Evaporation Source 1011b Evaporation source 1014a Rotation plate 1014b Rotation plate 1014c Rotation plate 1014d Rotation plate 1015a Processed object 1015b Processed object 1015c Processed object 1015d Processed object 1021a Evaporation source 1021b Evaporation source 1025a Processed object 1031a Evaporation source 1031b Evaporation source

Claims (15)

A layer containing a light-emitting substance between a pair of electrodes, the layer containing the light-emitting substance has a layer containing a composite material, and the layer containing the composite material contains an organic compound and a transition metal oxide ; A light-emitting element, wherein a concentration ratio between the organic compound and the transition metal oxide is periodically changed in a stacking direction. A layer containing a light-emitting substance between a pair of electrodes, the layer containing the light-emitting substance has a layer containing a composite material, and the layer containing the composite material contains an organic compound and a transition metal oxide ; The light-emitting element, wherein the concentration of the transition metal oxide periodically changes in the stacking direction. 3. The light-emitting element according to claim 1, wherein a concentration of the transition metal oxide is 5 wt% or more and 90 wt% or less. 3. The light-emitting element according to claim 1, wherein the concentration of the transition metal oxide is 10 wt% or more and 80 wt% or less. A layer containing a light-emitting substance between a pair of electrodes, the layer containing the light-emitting substance has a layer containing a composite material, and the layer containing the composite material contains an organic compound and a transition metal oxide ; A light-emitting element, wherein the concentration of the organic compound periodically changes in the stacking direction.   6. The light-emitting element according to claim 1, wherein the concentration of the organic compound is 10 wt% or more and 95 wt% or less.   6. The light-emitting element according to claim 1, wherein the concentration of the organic compound is 20 wt% or more and 90 wt% or less.   8. The light-emitting element according to claim 1, wherein one cycle of the periodic change is not less than 0.5 nm and not more than 30 nm.   8. The light-emitting element according to claim 1, wherein one period of the periodic change is 1 nm or more and 10 nm or less.   10. The light-emitting element according to claim 1, wherein the layer including the composite material is provided in contact with one electrode of the pair of electrodes.   10. The light-emitting element according to claim 1, wherein the layer including the composite material is provided in two layers so as to be in contact with the pair of electrodes. 12. The transition metal oxide according to claim 1, wherein the transition metal oxide is titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide. A light-emitting element characterized by being one or more of rhenium oxide. In any one of claims 1 to 12, wherein the organic compound, the light emitting device characterized by having a hole transporting property. In any one of claims 1 to 12, wherein the organic compound, the light emitting element characterized in that an organic compound having an organic compound or a carbazole skeleton having an arylamine skeleton. A light emitting device having a light-emitting element according to any one of claims 1 to 14, and a control means for controlling light emission of the light emitting element.