JP5132041B2 - LIGHT EMITTING DEVICE AND ELECTRIC DEVICE - Google Patents

Description

  The present invention relates to a light-emitting element having a pair of electrodes and a layer containing an organic compound that can emit light by applying an electric field. Further, the present invention relates to a light emitting device having such a light emitting element.

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

  The light emitting mechanism of the light emitting element is molecular excitation by applying a voltage with a light emitting layer sandwiched between a pair of electrodes, so that electrons injected from the cathode and holes injected from the anode recombine at the light emitting center of the light emitting layer. It is said that when a molecular exciton returns to the ground state, it emits energy and emits light. Singlet excitation and triplet excitation are known as excited states, and light emission is considered to be possible through either excited state.

  With respect to such a light emitting element, improvement of the element structure, material development, and the like are performed in order to improve the element characteristics.

  For example, as a means to improve the external quantum efficiency without controlling the distance between the light emitting region and the reflective metal and without deteriorating the luminance, the ITO is sandwiched between the light emitting unit and the reflective metal and reflected from the light emitting unit. There is a method of controlling the optical distance L to the electrode (for example, see Patent Document 1).

  An outline of the element configuration disclosed in Patent Document 1 is shown in FIG. The transparent electrode 201, the light emitting unit 202, the transparent conductive film 203, and the metal electrode 204 are stacked, and the optical distance L between the metal electrode and the light emitting region is optimized by adjusting the film thickness of the transparent conductive film 203. , Improving the external quantum efficiency.

However, according to the configuration of Patent Document 1, since the transparent conductive film 203 and the reflective metal (metal electrode) 204 are in contact with each other, there is a fear of electrolytic corrosion due to a difference in natural potential (see, for example, Patent Document 2). . Patent Document 2 describes a natural potential when a 3.5% sodium chloride aqueous solution (liquid temperature 27 ° C.) is used and the reference electrode is measured using silver / silver chloride. Under this condition, the natural potential of aluminum known as a reflective metal having a high reflectance is about −1550 mV, and the natural potential of ITO (In ₂ O ₃ -10 wt% SnO ₂ ) which is a transparent conductive film is about −1000 mV. The difference was large, and there was a high possibility that the oxidation-reduction reaction proceeded at the interface between aluminum and ITO, resulting in electrolytic corrosion.
JP 2003-272855 A JP 2003-89864 A

  Note that the natural potential is a potential shown to the reference electrode in a state where no current is applied from the outside when the reactant is immersed in a solution, that is, a potential in a closed circuit, and is also called a static potential.

  In view of the above problems, the present invention provides a light-emitting element and a light-emitting element that can prevent electrolytic corrosion between the transparent conductive film and the reflective metal in a light-emitting element having a layer containing a light-emitting substance and a transparent conductive film between a pair of electrodes. It is an object of the present invention to provide a light emitting device using the above.

  The present invention provides a first layer containing a light-emitting substance, a second layer containing an N-type semiconductor, a third layer composed of a transparent conductive film, and a hole transport medium including a hole transport medium between an anode and a cathode. A first layer containing a luminescent substance, a second layer containing an N-type semiconductor, a third layer composed of a transparent conductive film, and a fourth layer containing a material that serves as a hole transport medium Are provided in order, and the cathode has a layer containing a reflective metal.

  In the above configuration, examples of the reflective metal include aluminum (Al), silver (Ag), or an AlLi alloy and an MgAg alloy that are alloys containing these.

  In addition, as a material constituting the third layer made of the transparent conductive film, indium tin oxide, indium tin oxide containing silicon, indium oxide containing 2 to 20% zinc oxide, or the like can be used. .

  In the above structure, the second layer including the N-type semiconductor and the fourth layer including the hole transport medium may each be configured as a single layer, or a plurality of layers are stacked. Also good. Here, the N-type semiconductor is preferably a metal oxide, and particularly preferably any one or more compounds selected from the group consisting of zinc oxide, tin oxide, and titanium oxide.

  The present invention includes a first layer containing a luminescent substance, a second layer containing an organic compound and a substance exhibiting electron donating properties, a third layer composed of a transparent conductive film, between the anode and the cathode, A fourth layer containing a hole transport medium, a first layer containing a light-emitting substance, a second layer containing an N-type semiconductor, a third layer composed of a transparent conductive film, and a material to be a hole transport medium A fourth layer including s is provided in order, and the cathode has a layer including a reflective metal.

  In the above structure, the second layer containing the organic compound and the electron-donating substance and the fourth layer containing the hole transport medium may each be a single layer, or a plurality of layers may be stacked. It may be a configuration. Here, the organic compound is preferably an organic compound exhibiting an electron transporting property, and in particular, a metal complex having a ligand including a π-conjugated skeleton is preferable. The substance exhibiting an electron donating property is preferably an alkali metal, an alkaline earth metal, or a rare earth metal.

  Further, in the above configuration, the cathode may be configured by a single layer of reflective metal, or may be configured by stacking a reflective metal and another electrode material.

  By adopting the structure of the present invention, the reflective metal and the transparent conductive film are not in direct contact with each other, so that electric corrosion due to a difference in natural potential can be prevented.

  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.

  In the present invention, of the pair of electrodes of the light-emitting element, an electrode functioning as an anode refers to an electrode that can emit light when a voltage is applied so that the electrode is higher and functions as a cathode. An electrode is an electrode from which light emission is obtained when a voltage is applied so that the electrode is lower.

(Embodiment 1)
In FIG. 1, the element structure of the light emitting element in this invention is typically shown. In the light-emitting element of the present invention, the first layer 102, the second layer 103, the third layer 104, and the fourth layer 105 are provided between the anode 101 and the cathode 106 in the direction from the anode 101 to the cathode 106. On the other hand, it is the structure provided in order.

  In this embodiment mode, the cathode 106 is made of a reflective metal, and light emitted from the first layer 102 is extracted from the anode side.

  As the anode 101, a light-transmitting material is preferably used. Specifically, indium tin oxide (abbreviation: ITO), indium tin oxide containing silicon, or 2 to 20% zinc oxide is used. Indium oxide or the like can be used.

  The first layer 102 is a layer containing a light emitting substance and is made of a known material. The first layer 102 may be composed of a single layer or may be composed of a plurality of layers. For example, in addition to the light emitting layer, functional layers such as an electron injection layer, an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer may be freely combined and provided. Moreover, you may form the mixed layer or mixed junction which combined these each layer. The layer structure of the light emitting layer can be changed. Instead of having a specific electron injection region or light emitting region, the light emitting layer can be provided with an electrode exclusively for electron injection or with a light emitting material dispersed. Such modifications can be permitted without departing from the spirit of the present invention.

The second layer 103 is a layer including a material having a donor level that generates electrons. Specifically, it may be composed of an N-type semiconductor such as zinc oxide, tin oxide, titanium oxide, zinc sulfide, zinc selenide, or zinc telluride, or any structure including these N-type semiconductors. Alternatively, the organic compound may be doped with a substance exhibiting electron donating properties. The organic compound at this time is preferably an electron transporting material, such as 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), OXD-7, TAZ, p-EtTAZ, BPhen, and BCP mentioned above, and Alq ₃ , tris (5-methyl-8-quinolinolato) aluminum (abbreviated as: Almq ₃ ), bis (10-hydroxybenzo [h] -quinolinato) beryllium abbreviation: BeBq ₂ ) and other metal complexes having a quinoline skeleton or a benzoquinoline skeleton, and bis (2-methyl-8-quinolinolato) -4-phenyl And phenolate-aluminum (abbreviation: BAlq). On the other hand, examples of the substance exhibiting an electron donating property include alkali metals such as Li and Cs, alkaline earth metals such as Mg, Ca, Sr, and Ba, and rare earth metals such as Er and Yb. In addition, for example, an organic compound such as tetrathiafulvalene or tetramethylthiafulvalene that exhibits an electron donating property to Alq ₃ may be used.

  The third layer 104 is a layer having a light-transmitting property and containing a material that generates carriers. Specifically, a transparent conductive film such as indium tin oxide (abbreviation: ITO), indium tin oxide containing silicon, or indium oxide containing 2 to 20% zinc oxide can be used.

  The fourth layer 105 is a layer containing a hole transport medium. Examples of the hole transport medium include a hole transport material made of an organic compound, a material obtained by doping an organic compound with a substance that exhibits electron acceptability, and a hole transport material made of an inorganic compound. These hole transport media can be used for the fourth layer 105, but more preferably, a material having an acceptor level that generates holes, that is, a material in which an organic compound is doped with a substance exhibiting electron accepting properties. Alternatively, a hole transporting material made of an inorganic compound may be used.

  When the fourth layer includes a hole transporting material made of an organic compound, the hole transporting material to be used is preferably a compound having an aromatic amine skeleton (that is, having a benzene ring-nitrogen bond). It is. As a widely used material, for example, N, N′-bis (3-methylphenyl) -N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviation: TPD) In addition, its derivatives 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: α-NPD) and 4,4 ′, 4 ″ -tris ( N-carbazolyl) -triphenylamine (abbreviation: TCTA), 4,4 ′, 4 ″ -tris (N, N-diphenyl-amino) -triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ′ And starburst aromatic amine compounds such as' -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (abbreviation: MTDATA).

  When the fourth layer 105 has a structure in which an organic compound is doped with an electron-accepting substance, a hole-transporting material is preferable as the organic compound to be used, and a compound having an aromatic amine skeleton is preferable. . For example, in addition to TPD, α-NPD which is a derivative thereof, or starburst type aromatic amine compounds such as TDATA and MTDATA can be mentioned. On the other hand, examples of the substance exhibiting electron acceptability include metal oxides such as molybdenum oxide, vanadium oxide, and rhenium oxide, which exhibit electron acceptability with respect to α-NPD. Alternatively, an organic compound such as tetracyanoquinodimethane (abbreviation: TCNQ) or 2,3-dicyanonaphthoquinone (abbreviation: DCNNQ) which exhibits an electron accepting property with respect to α-NPD may be used.

  In the case where the fourth layer 105 includes a hole transporting material composed of an inorganic compound, the fourth layer 105 is composed of a P-type semiconductor such as vanadium oxide, chromium oxide, molybdenum oxide, cobalt oxide, or nickel oxide. Or what is necessary is just the structure containing those P-type semiconductors.

  Further, as the cathode 106, a metal having high reflectance is preferably used, and aluminum (Al), silver (Ag), or an AlLi alloy, an MgAg alloy, or the like containing these can be used. The cathode 106 may have a laminated structure of a reflective metal and another electrode material. For example, a laminated structure such as a laminated layer of calcium (Ca) and Ag, a laminated layer of Ca and Al, and a laminated layer of Li and Al. It is good. By forming a thin film (for example, about 5 nm) of an alkali metal or alkaline earth metal and laminating it with a reflective metal, it is possible to improve the electron injecting property.

  In the structure shown in this embodiment mode, the fourth layer 105 is provided between the cathode 106 and the third layer 104, and the cathode 106 made of a reflective metal and the transparent conductive film are used. The third layer 104 is not in direct contact. Therefore, it is possible to prevent electrolytic corrosion due to a difference in natural potential. That is, it can prevent that a reflective metal and a transparent conductive film react.

  In addition, since the film thickness of the fourth layer 105 as well as the third layer 104 formed of a transparent conductive film can be freely set, the light-emitting region in the first layer 102 containing a light-emitting substance can be used. The degree of freedom for optimizing the optical distance L to the reflective metal is further expanded. Therefore, it becomes easier to optimize the optical distance so as to improve the external quantum efficiency, and to optimize the optical distance so as to improve the color purity of the emitted color.

  Since the first layer 102, the second layer 103, the third layer 104, the fourth layer 105, and the cathode 106 are stacked, electrons and holes are generated from the third layer. It becomes possible. The electrons generated from the third layer 104 include a material having a donor level in which the second layer 103 generates electrons, and thus, an electron transfer barrier from the third layer 104 to the second layer 103. Is small, easily moves to the second layer 103, recombines with holes injected from the anode in the first layer 102, and emits light. On the other hand, the holes generated from the third layer have a low barrier for hole movement from the third layer 104 formed of the transparent conductive film to the fourth layer 105 including the hole transport medium, and the fourth layer easily It moves to the layer and is transported to the cathode 106.

  That is, in the configuration of the present invention, the substantial electron moving distance is shortened, and the driving voltage can be reduced. Therefore, when the optical distance is optimized to improve external quantum efficiency and color purity and the distance from the light emitting region in the layer containing the light emitting material to the reflective metal is set to a certain distance, the present invention can be used to The substantial moving distance is shortened, and the driving voltage can be reduced.

  Further, in order to optimize the optical distance, it is possible to suppress an increase in driving voltage even when the distance from the light emitting region in the layer containing the light emitting substance to the reflective metal is increased and the film thickness is increased. .

  Further, the contact resistance between the second layer 103 and the fourth layer 105 can be reduced by stacking the second layer 103 and the fourth layer 105 with the third layer 104 interposed therebetween. Is possible. Therefore, the driving voltage can be further reduced. In addition, the presence of the third layer 104 therebetween widens the range of selection of materials constituting the second layer 103 and the fourth layer 105.

  Note that the contact resistance between the second layer 103 and the third layer 104 and the contact resistance between the third layer 104 and the fourth layer 105 are preferably small.

  In this example, the structure of the light-emitting element of the present invention will be described with reference to FIG.

  First, the anode 301 of the light emitting element is formed over the substrate 300. The material is ITO, which is a transparent conductive film, and is formed with a film thickness of 110 nm by a sputtering method. The shape of the anode 301 is 2 mm square.

  Next, a first layer 302 containing a light-emitting substance is formed over the anode 301. Note that the first layer 302 containing a light-emitting substance in this embodiment has a stacked structure including three layers 311, 312, and 313.

  The substrate on which the anode 301 was formed was fixed to the substrate holder of the vacuum deposition apparatus with the surface on which the anode 301 was formed facing downward, and copper phthalocyanine (hereinafter referred to as Cu-Pc) was attached to the evaporation source provided in the vacuum deposition apparatus. And a hole injection layer 311 made of a hole injecting material with a thickness of 20 nm is formed by an evaporation method using a resistance heating method. Note that a known hole injecting material can be used as a material for forming the hole injecting layer 311.

  Next, the hole transport layer 312 is formed using a material having excellent hole transportability. As a material for forming the hole transport layer 312, a known hole transport material can be used. In this embodiment, α-NPD is formed with a film thickness of 40 nm by the same method.

Next, the light emitting layer 313 is formed. As a material for forming the light-emitting layer 313, a known light-emitting substance can be used. In this embodiment, Alq ₃ is formed with a thickness of 40 nm by a similar method.

In this manner, the three layers 311, 312, and 313 are stacked and formed. Next, the second layer 303 is formed. In this embodiment, Alq ₃ is used as an electron transporting material (host material), Mg is used as a substance (guest material) showing electron donating property to Alq ₃ , and the second film is formed by a co-evaporation method with a film thickness of 30 nm. Layer 303 is formed. The proportion of the guest material is 1% by mass.

  Next, a third layer 304 is formed. In this embodiment, ITO is used to form a transparent conductive layer with a thickness of 140 nm.

  Next, a fourth layer 305 is formed. In this example, α-NPD is used as a hole transporting material (host material), molybdenum oxide is used as a substance (guest material) that exhibits electron accepting property with respect to α-NPD, and the film thickness is 150 nm by a co-evaporation method. A third layer is formed. The proportion of the guest material is 25% by mass.

  Next, the cathode 306 is formed by sputtering or evaporation. Note that in this embodiment, the cathode 306 is obtained by forming aluminum (150 nm) over the fourth layer 305 by an evaporation method.

  As described above, the light-emitting element of the present invention is formed. In the structure shown in this embodiment, light generated by carrier recombination in the first layer containing a light-emitting substance is emitted from the anode 301 to the outside.

  In the structure shown in this embodiment, since the fourth layer is provided between the third layer ITO and the cathode aluminum, the ITO and aluminum are not in direct contact with each other. It is possible to prevent electrolytic corrosion due to the difference between the potential and the natural potential of aluminum.

  Moreover, since the film thicknesses of the third layer and the fourth layer can be freely set, it is easier to optimize the optical distance L between the light emitting region in the first layer and the cathode made of the reflective metal. .

  Further, since carriers can be generated from the third layer, the moving distance of electrons becomes shorter than that of a conventional element, and the driving voltage can be reduced.

  In this example, the structure of the light-emitting element of the present invention will be described with reference to FIG.

  Note that the substrate 400, the anode 401, the first layer 402, the second layer 403, the third layer 404, the fourth layer 405, and the cathode 406 are formed using the same materials as in Embodiment 1. Therefore, the description is omitted.

In FIG. 4, the cathode 406 is formed over the substrate 400, the fourth layer 405 is formed over the cathode 406, the third layer 404 is formed over the fourth layer 405, and the third layer 404 is formed. A second layer 403 is formed thereon, a first layer 402 containing a light-emitting substance is formed over the second layer 403, and an anode 401 is formed thereover.

  In the structure shown in this embodiment, light generated by carrier recombination in the first layer containing a light-emitting substance is emitted from the anode 401 to the outside.

  Also in the structure shown in this embodiment, the same effect as the structure shown in Embodiment 1 can be obtained. Specifically, since the fourth layer is provided between the third layer and the cathode, electrolytic corrosion due to a difference in natural potential can be prevented. Moreover, since the film thicknesses of the third layer and the fourth layer can be freely set, it is easier to optimize the optical distance L between the light emitting region in the first layer and the cathode made of the reflective metal. . Further, since carriers can be generated from the third layer, the moving distance of electrons becomes shorter than that of a conventional element, and the driving voltage can be reduced.

  In this embodiment, a light-emitting device having the light-emitting element of the present invention in a pixel portion will be described with reference to FIG. 5A is a top view illustrating the light-emitting device, and FIG. 5B is a cross-sectional view taken along line A-A ′ in FIG. 5A. Reference numeral 501 indicated by a dotted line denotes a driving circuit portion (source side driving circuit), 502 denotes a pixel portion, and 503 denotes a driving circuit portion (gate side driving circuit). Further, reference numeral 504 denotes a sealing substrate, 505 denotes a sealing material, and the inside surrounded by the sealing material 505 is a space 507.

  Reference numeral 508 denotes a wiring for transmitting signals input to the source side driver circuit 501 and the gate side driver circuit 503, and a video signal, a clock signal, and a start signal from an FPC (flexible printed circuit) 509 serving as an external input terminal. Receive a reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.

  Next, a cross-sectional structure is described with reference to FIG. A driver circuit portion and a pixel portion are formed over the element substrate 510. Here, a source side driver circuit 501 which is a driver circuit portion and a pixel portion 502 are shown.

  Note that the source side driver circuit 501 is a CMOS circuit in which an n-channel TFT 523 and a p-channel TFT 524 are combined. The TFT forming the driving circuit may be formed by a known CMOS circuit, PMOS circuit or NMOS circuit. In this embodiment mode, a mode in which the pixel portion and the driver circuit are formed over the same substrate is shown; however, this is not necessarily required, and the driver circuit is formed not on the substrate on which the pixel portion is formed but outside. You can also.

  The pixel portion 502 is formed by a plurality of pixels including a switching TFT 511, a current control TFT 512, and a first electrode 513 electrically connected to the drain of the current control TFT. Note that an insulator 514 is formed so as to cover an end portion of the first electrode 513. Here, a positive photosensitive acrylic resin film is used.

  In order to improve the coverage, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 514. For example, in the case where positive photosensitive acrylic is used as a material for the insulator 514, it is preferable that only the upper end portion of the insulator 514 has a curved surface having a curvature radius (0.2 μm to 3 μm). The insulator 514 can be either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light, and is not limited to an organic compound. For example, both silicon oxide, silicon oxynitride, siloxane, and the like can be used.

  A first layer to a fourth layer 516 and a second electrode 517 are formed over the first electrode 513, respectively. Here, as a material used for the first electrode 513, a light-transmitting material is preferably used. For example, indium tin oxide (ITO), indium tin oxide containing silicon, indium oxide containing 2 to 20% zinc oxide (ZnO), or the like can be used.

  The first to fourth layers 516 are formed by an evaporation method using an evaporation mask or an inkjet method. The first to fourth layers 516 include a first layer and a second layer containing a light-emitting substance, and a third layer and a fourth layer made of a transparent conductive film, The first layer, the second layer, the third layer, and the fourth layer are sequentially stacked in the direction from the anode to the cathode, and the fourth layer is formed in contact with the cathode. In addition, as a material used for a layer containing a light-emitting substance, an organic compound is usually used in a single layer, a stacked layer, or a mixed layer. In the present invention, an inorganic compound is used as part of a film made of an organic compound. The configuration is also included.

  Further, as a material used for the second electrode (cathode) 517 formed on the first to fourth layers 516, it is preferable to use a metal having high reflectivity, and aluminum (Al), silver (Ag), Alternatively, an AlLi alloy, an MgAg alloy, or the like that is an alloy containing these can be used.

  Further, the sealing substrate 504 is bonded to the element substrate 510 with the sealant 505, whereby the light-emitting element 518 is provided in the space 507 surrounded by the element substrate 510, the sealing substrate 504, and the sealant 505. Yes. Note that the space 507 is filled with a filler and may be filled with a sealant 505 in addition to the case of being filled with an inert gas (such as nitrogen or argon).

  Note that an epoxy-based resin is preferably used for the sealant 505. 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 504.

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

  For example, various electric appliances including a light-emitting device having the light-emitting element of the present invention as a display portion can be provided.

  As an electric device manufactured using a light-emitting device having the light-emitting element of the present invention, a video camera, a digital camera, a goggle-type display, a navigation system, an audio playback device (car audio, audio component, etc.), a computer, a game device, a mobile phone Information terminal (mobile computer, mobile phone, portable game machine, electronic book, etc.), image playback device equipped with a recording medium (specifically, playback of a recording medium such as a digital video disc (DVD), and display the image) And a device provided with a display device capable of performing the above. Specific examples of these electric devices are shown in FIGS.

  FIG. 6A illustrates a television receiver which includes a housing 9101, a support base 9102, a display portion 9103, a speaker portion 9104, a video input terminal 9105, and the like. It is manufactured by using a light-emitting device having the light-emitting element of the present invention for the display portion 9103. The television receiver includes all information display devices such as a computer, a TV broadcast receiver, and an advertisement display.

  FIG. 6B illustrates a computer, 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. It is manufactured by using a light emitting device having a light emitting element of the present invention for the display portion 9203.

  FIG. 6C illustrates a goggle type display, which includes a main body 9301, a display portion 9302, and an arm portion 9303. It is manufactured by using a light emitting device having a light emitting element of the present invention for the display portion 9302.

  FIG. 6D illustrates a mobile phone, 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. It is manufactured by using a light emitting device having a light emitting element of the present invention for the display portion 9403. Note that the display portion 9403 can suppress power consumption of the mobile phone by displaying white characters on a black background.

  FIG. 6E illustrates a video camera, 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, operation keys 9509, and an eyepiece. Part 9510 and the like. It is manufactured by using a light-emitting device having the light-emitting element of the present invention for the display portion 9502.

  As described above, the applicable range of the light-emitting device having the light-emitting element 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 element of the present invention, the optical distance from the light emitting region in the layer containing the light emitting substance to the reflective metal can be optimized without increasing the driving voltage.

3A and 3B each illustrate an element structure of a light-emitting element of the present invention. FIG. 9 illustrates an element structure of a conventional light-emitting element. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention. FIG. 6 illustrates a light-emitting device. The figure explaining an electric equipment.

Claims (9)

A light-emitting device having a light-emitting element provided on the first substrate in a space surrounded by a first substrate, a second substrate, and a sealing material,
The light emitting element is
A first layer including a light emitting substance between the anode and the cathode, a second layer including an organic compound and a substance exhibiting an electron donating property with respect to the organic compound, and a transparent conductive film. 3 layers and a fourth layer containing a hole transport medium,
The cathode has a layer comprising a reflective metal;
The first layer, the second layer, the third layer, the fourth layer, and the cathode are sequentially provided;
A light emitting device, wherein the space is filled with a gas. A light-emitting device having a light-emitting element provided on the first substrate in a space surrounded by a first substrate, a second substrate, and a sealing material,
The light emitting element is
A first layer including a light emitting substance between the anode and the cathode, a second layer including an organic compound and a substance exhibiting an electron donating property with respect to the organic compound, and a transparent conductive film. 3 layers and a fourth layer containing a hole transport medium,
The cathode has a layer comprising a reflective metal;
The first layer, the second layer, the third layer, the fourth layer, and the cathode are sequentially provided;
The space is filled with resin,
A light emitting device comprising the resin between the light emitting element and the second substrate .   3. The light-emitting device according to claim 1, wherein the organic compound included in the second layer is an organic compound exhibiting an electron transporting property.   3. The light-emitting device according to claim 1, wherein the organic compound included in the second layer is a metal complex having a ligand including a π-conjugated skeleton.   5. The light-emitting device according to claim 1, wherein the substance having an electron donating property is an alkali metal, an alkaline earth metal, or a rare earth metal.   5. The substance exhibiting electron donating property according to claim 1, wherein the substance exhibiting electron donating properties is one or more metals selected from the group consisting of Li, Cs, Mg, Ca, Ba, Er, and Yb. A light emitting device characterized by the above.   7. The light-emitting device according to claim 1, wherein the reflective metal is aluminum, silver, an alloy containing aluminum, or an alloy containing silver.   8. The transparent conductive film according to claim 1, wherein the transparent conductive film is any one of indium tin oxide, indium tin oxide containing silicon, and indium oxide containing 2 to 20% zinc oxide. A light emitting device characterized by the above.   An electrical apparatus using the light-emitting device according to claim 1 for a display portion.

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