JP4999308B2 - Light emitting element and light emitting device - Google Patents

Description

  The present invention relates to a light emitting device. In particular, the present invention relates to a light-emitting element including a composite layer in which an organic compound and an inorganic compound are mixed. Further, the present invention relates to a light emitting device having a light emitting element.

  In recent years, a current is passed through an organic compound such as a light-emitting element using a light-emitting organic compound (referred to as an organic light-emitting diode [OLED] or an organic EL element, hereinafter referred to as an organic EL element). Thus, a light-emitting element that can obtain high luminance is attracting attention.

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

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

  Since such an organic EL element is usually formed with a thin film of about submicron, it is a great advantage that it can be made thin and light. In addition, since the time from the injection of the carrier to the light emission is about microseconds or less, one of the features is that the response speed is very fast. Further, since sufficient light emission can be obtained with a DC voltage of several volts to several tens of volts, power consumption is relatively small. Because of these advantages, organic EL elements are attracting attention as next-generation flat panel display elements.

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

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

On the other hand, an attempt has been made to form a light-emitting element using a layer in which an organic compound and an inorganic compound are mixed instead of an organic thin film. For example, Patent Document 1 below discloses a light-emitting element using a light-emitting layer in which fluorescent organic molecules are dispersed in a metal oxide. Patent Document 2 below also discloses a light-emitting element formed by laminating a layer in which an organic compound (a hole transporting compound, an electron transporting compound, or a light emitting compound) is dispersed through a covalent bond in a silica matrix. Yes. In these documents, it is reported that the durability and heat resistance of the element are improved.
C. W. Tan (C.W. Tang), 1 outside, Applied Physics Letters, Vol. 51, no. 12, 913-915 (1987) JP-A-2-288092 JP 2000-306669 A

  In the light-emitting elements disclosed in Patent Document 1 and Patent Document 2 described above, since an organic compound is simply dispersed in an insulating metal oxide, the current is higher than that of a conventional organic EL element. Is difficult to flow (that is, the voltage required to pass a certain current increases).

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

  Further, in order to suppress a short circuit of the light emitting element due to dust or the like, it is effective to increase the film thickness of the light emitting element, but the configuration as shown in Patent Document 1 or Patent Document 2 is effective. When the film thickness is increased, the increase in drive voltage becomes more apparent. That is, in the conventional configuration, it is practically difficult to increase the film thickness.

  FIG. 2 shows a conventional light-emitting element disclosed in Patent Document 2, in which an organic compound is dispersed in a silica matrix between a first electrode (anode) 201 and a second electrode (cathode) 202. The composite layer 203 is sandwiched. That is, the composite layer 203 is entirely composed of a silica matrix, 211 is a hole transport layer in which a hole transport compound is dispersed in a silica matrix, and 213 is an electron transport layer in which an electron transport compound is dispersed in a silica matrix. Reference numeral 212 denotes a light emitting layer in which a light emitting compound is dispersed in a silica matrix. When a voltage is applied to this element, holes are injected from the first electrode (anode) 201 and electrons are injected from the second electrode (cathode) 202, recombined in the light emitting layer 212, and the light emitting compound emits light. it is conceivable that.

  Carrier transport in this element is carried out by the hole transport layer 211 and the electron transport layer 213, but there is a problem that an electric current hardly flows because an organic compound is dispersed in an insulating silica matrix. For example, in the hole transport layer 211, holes move by hopping between hole transport compounds present in the hole transport layer 211, and the insulating silica matrix does not participate in hole transport. On the contrary, it will hinder hole hopping. The same can be said for the electron transport layer 213. Therefore, as a matter of course, the driving voltage rises as compared with the conventional organic EL element.

  Further, even if an attempt is made to increase the film thickness of the composite layer 203 for the purpose of preventing a short circuit of an element or performing an optical design, the increase in the driving voltage described above becomes more remarkable. It is difficult in practice.

  In view of the above, an object of the present invention is to provide a light-emitting element having a novel structure which is different from the conventional one using a layer formed by mixing an organic compound and an inorganic compound. It is another object of the present invention to provide a light-emitting element using a layer in which an organic compound and an inorganic compound are mixed and having a low driving voltage. It is another object of the present invention to provide a light-emitting element that uses a layer formed by mixing an organic compound and an inorganic compound and can easily prevent a short circuit.

  As a result of intensive studies, the present inventor has found that the problem can be solved by applying a layer containing an organic compound and an inorganic compound that can exchange electrons with the organic compound.

  That is, the structure of the present invention is a light-emitting element in which a composite layer containing an organic compound and an inorganic compound is sandwiched between a pair of electrodes, and the composite layer includes a first layer, a first layer, The first layer includes a first organic compound and a first inorganic compound that exhibits an electron accepting property with respect to the first organic compound, and The second layer includes a second organic compound that emits light and a second inorganic compound, and the third layer has an electron donating property to the third organic compound and the third organic compound. And a third inorganic compound.

  At this time, the first organic compound is preferably a hole transporting organic compound, and more preferably an organic compound having an aromatic amine skeleton. The third organic compound is preferably an electron-transporting organic compound, and more preferably a chelate metal complex having a chelate ligand containing an aromatic ring, an organic compound having a phenanthroline skeleton, or an oxa It is an organic compound having a diazole skeleton.

  The first inorganic compound is preferably a metal oxide or a metal nitride, more preferably a transition metal oxide of any one of Groups 4 to 12 of the periodic table. Among them, many transition metal oxides in Groups 4 to 8 of the periodic table have high electron accepting properties, and vanadium oxide, molybdenum oxide, rhenium oxide, and tungsten oxide are particularly preferable.

  The second inorganic compound is preferably a metal oxide or a metal nitride, more preferably a Group 13 or Group 14 metal oxide of the periodic table. This is because these metal oxides are difficult to quench the light emission of the second organic compound that coexists in the second layer. Among these, aluminum oxide, gallium oxide, silicon oxide, and germanium oxide are particularly preferable.

  The third inorganic compound is preferably a metal oxide or a metal nitride, more preferably an alkali metal oxide, an alkaline earth metal oxide, a rare earth metal oxide, an alkali metal nitride, or an alkaline earth metal nitride. , Rare earth metal nitride. Many of these metal oxides and metal nitrides have high electron donating properties, and lithium oxide, barium oxide, lithium nitride, magnesium nitride, and calcium nitride are particularly preferable.

  Another structure of the present invention is a light-emitting element in which a composite layer containing an organic compound and an inorganic compound is sandwiched between a pair of electrodes, and the composite layer is formed by sequentially laminating a first layer. A first layer that is electron-accepting with respect to the first organic compound and the first organic compound, the first layer being composed of a layer, a second layer, a third layer, and a fourth layer. The second layer includes a second organic compound that emits light and the second inorganic compound, and the third layer includes the third organic compound and the third organic compound. A fourth inorganic compound having an electron accepting property with respect to the compound, wherein the fourth layer has an electron accepting property with respect to the fourth organic compound and the fourth organic compound. The light emitting element containing these.

  At this time, the first organic compound and / or the fourth organic compound is preferably a hole transporting organic compound, and more preferably an organic compound having an aromatic amine skeleton. The third organic compound is preferably an electron-transporting organic compound, and more preferably a chelate metal complex having a chelate ligand containing an aromatic ring, an organic compound having a phenanthroline skeleton, or an oxa It is an organic compound having a diazole skeleton.

  The first inorganic compound and / or the fourth inorganic compound is preferably a metal oxide or a metal nitride, and more preferably a transition metal oxide of any one of Groups 4 to 12 of the periodic table. . Among them, many transition metal oxides in Groups 4 to 8 of the periodic table have high electron accepting properties, and vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide are particularly preferable.

  The second inorganic compound is preferably a metal oxide or a metal nitride, more preferably a Group 13 or Group 14 metal oxide of the periodic table. This is because these metal oxides are difficult to quench the light emission of the second organic compound that coexists in the second layer. Among these, aluminum oxide, gallium oxide, silicon oxide, and germanium oxide are particularly preferable.

  The third inorganic compound is preferably a metal oxide or a metal nitride, more preferably an alkali metal oxide, an alkaline earth metal oxide, a rare earth metal oxide, an alkali metal nitride, or an alkaline earth metal nitride. , Rare earth metal nitride. Many of these metal oxides and metal nitrides have high electron donating properties, and lithium oxide, barium oxide, lithium nitride, magnesium nitride, and calcium nitride are particularly preferable.

  Unlike the conventional light-emitting element having a layer in which an organic compound and an inorganic compound are simply mixed, the above-described light-emitting element of the present invention is characterized in that a current can easily flow and a driving voltage can be reduced. A light-emitting device having an element can also reduce power consumption. Therefore, a light-emitting device having the light-emitting element of the present invention is also included in the present invention.

  Note that a light-emitting device in this specification refers to an image display device or a light emitter using a light-emitting element. Also, a module in which a connector such as an anisotropic conductive film (FPC), a TAB (Tape Automated Bonding) tape or a TCP (Tape Carrier Package) is attached to the light emitting element, a printed wiring on the end of the TAB tape or TCP It is assumed that the light-emitting device also includes a module provided with a plate or a module in which an IC (integrated circuit) is directly mounted on a light-emitting element by a COG (Chip On Glass) method.

  By implementing the present invention, a light-emitting element having a novel structure different from the conventional one using a layer formed by mixing an organic compound and an inorganic compound can be provided. In addition, a light-emitting element with a low driving voltage using a layer formed by mixing an organic compound and an inorganic compound can be provided. Further, a light-emitting element that uses a layer formed by mixing an organic compound and an inorganic compound and can easily prevent a short circuit can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode.

[Embodiment 1]
FIG. 1 shows an element structure of a light-emitting element of the present invention, in which a composite layer 103 formed by mixing an organic compound and an inorganic compound is sandwiched between a first electrode 101 and a second electrode 102. Although it is an element, the structure in the composite layer 103 is completely different from the composite layer 203 of the conventional light emitting element (FIG. 2). As illustrated, the composite layer 103 includes a first layer 111, a second layer 112, and a third layer 113, and the first layer 111 and the third layer 113 are particularly significant.

  First, the first layer 111 is a layer having a function of transporting holes to the second layer 112. The first layer 111 has at least a first organic compound and a first organic compound having an electron accepting property with respect to the first organic compound. It is a structure containing an inorganic compound. What is important is not simply that the first organic compound and the first inorganic compound are mixed, but the first inorganic compound exhibits an electron accepting property with respect to the first organic compound. By adopting such a configuration, a large number of hole carriers are generated in the first organic compound having essentially no inherent carriers, and extremely excellent hole injection / transport properties are exhibited.

  Therefore, the first layer 111 has not only an effect (such as improvement in heat resistance) considered to be obtained by mixing an inorganic compound, but also excellent conductivity (in particular, in the first layer 111, hole injection). And transportability) can also be obtained. This is an effect that cannot be obtained with the conventional hole transport layer 211 (FIG. 2) in which an organic compound and an inorganic compound that do not have an electronic interaction with each other are simply mixed. Due to this effect, the drive voltage can be made lower than in the prior art. In addition, since the first layer 111 can be thickened without causing an increase in driving voltage, a short circuit of an element due to dust or the like can be suppressed.

By the way, as described above, since hole carriers are generated in the first organic compound, the first organic compound is preferably a hole-transporting organic compound. Examples of the hole transporting organic compound include phthalocyanine (abbreviation: H ₂ Pc), copper phthalocyanine (abbreviation: CuPc), vanadyl phthalocyanine (abbreviation: VOPc), 4,4 ′, 4 ″ -tris (N, N -Diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA), 1,3 , 5-tris [N, N-di (m-tolyl) amino] benzene (abbreviation: m-MTDAB), 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: NPB), 4,4'-bis {N -[4-Di ( -Tolyl) amino] phenyl-N-phenylamino} biphenyl (abbreviation: DNTPD), 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (abbreviation: TCTA), and the like. There is no limit. Among the above-mentioned compounds, aromatic amine compounds represented by TDATA, MTDATA, m-MTDAB, TPD, NPB, DNTPD, TCTA, etc. are likely to generate hole carriers and are suitable as the first organic compound. A group.

  On the other hand, the first inorganic compound may be anything as long as it can easily receive electrons from the first organic compound, and various metal oxides or metal nitrides can be used. Any transition metal oxide belonging to Group 12 is preferable because it easily exhibits electron acceptability. Specific examples include titanium oxide, zirconium oxide, vanadium oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, and zinc oxide. Among the metal oxides described above, any of the transition metal oxides in Groups 4 to 8 of the periodic table has a high electron accepting property and is a preferred group. Vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide are particularly preferable because they can be vacuum-deposited and are easy to handle.

  Note that the first layer 111 may be formed by stacking a plurality of layers to which the above-described combination of an organic compound and an inorganic compound is applied. Moreover, other organic compounds or other inorganic compounds may be further contained.

  Next, the third layer 113 will be described. The third layer 113 is a layer having a function of transporting electrons to the second layer 112, and includes at least a third organic compound and a third inorganic compound that exhibits an electron donating property with respect to the third organic compound. It is the structure containing these. What is important is not that the third organic compound and the third inorganic compound are merely mixed, but that the third inorganic compound exhibits an electron donating property with respect to the third organic compound. By adopting such a structure, many electron carriers are generated in the third organic compound which has essentially no intrinsic carrier, and exhibits extremely excellent electron injecting / transporting properties.

  Therefore, the third layer 113 has not only an effect (such as improvement in heat resistance) considered to be obtained by mixing an inorganic compound, but also excellent conductivity (especially in the third layer 113, electron injection). And transportability) can also be obtained. This is an effect that cannot be obtained with the conventional electron transport layer 213 (FIG. 2) in which an organic compound and an inorganic compound that do not have an electronic interaction with each other are simply mixed. Due to this effect, the drive voltage can be made lower than in the prior art. In addition, since the third layer 113 can be thickened without causing an increase in driving voltage, a short circuit of an element due to dust or the like can be suppressed.

By the way, as described above, since an electron carrier is generated in the third organic compound, the third organic compound is preferably an electron-transporting organic compound. Examples of the electron-transporting organic compound include tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), and bis (10-hydroxybenzo [ h] -quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (abbreviation: BAlq), bis [2- (2′-hydroxyphenyl) benzoxa Zolato] zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2′-hydroxyphenyl) benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 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) 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 3- (4-biphenylyl) -4-phenyl -5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-biphenylyl) -4- (4-ethylphenyl) -5- (4-tert-butyl) Phenyl) -1,2,4-triazole (abbreviation: p-EtTAZ) and the like, but are not limited thereto. Among the above-mentioned compounds, a chelate metal complex having a chelate ligand containing an aromatic ring represented by Alq ₃ , Almq ₃ , BeBq ₂ , BAlq, Zn (BOX) ₂ , Zn (BTZ) ₂ , Organic compounds having a phenanthroline skeleton typified by BPhen, BCP, etc., and organic compounds having an oxadiazole skeleton typified by PBD, OXD-7, etc., are likely to generate electron carriers and are suitable as a third organic compound. Compound group.

  On the other hand, the third inorganic compound may be anything as long as it easily gives electrons to the third organic compound, and various metal oxides or metal nitrides can be used. Earth metal oxides, rare earth metal oxides, alkali metal nitrides, alkaline earth metal nitrides, and rare earth metal nitrides are preferable because they easily exhibit electron donating properties. Specific examples include lithium oxide, strontium oxide, barium oxide, erbium oxide, lithium nitride, magnesium nitride, calcium nitride, yttrium nitride, and lanthanum nitride. In particular, lithium oxide, barium oxide, lithium nitride, magnesium nitride, and calcium nitride are preferable because they can be vacuum-deposited and are easy to handle.

  Note that the third layer 113 may be formed by stacking a plurality of layers to which a combination of the above-described organic compound and inorganic compound is applied. Moreover, other organic compounds or other inorganic compounds may be further contained.

  Next, the second layer 112 will be described. The second layer 112 is a layer having a light emitting function and includes at least a light emitting second organic compound and a second inorganic compound. The second layer 112 may have a structure similar to that of the light-emitting layer 212 in FIG. 2, and can be formed by mixing various light-emitting organic compounds and inorganic compounds. However, since it is considered that the second layer 112 is less likely to flow current than the first layer 111 and the third layer 113, the thickness thereof is preferably about 10 nm to 100 nm.

The second organic compound is not particularly limited as long as it is a luminescent organic compound. For example, 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 9,10-di (2 -Naphthyl) -2-tert-butylanthracene (abbreviation: t-BuDNA), 4,4'-bis (2,2-diphenylvinyl) biphenyl (abbreviation: DPVBi), coumarin 30, coumarin 6, coumarin 545, coumarin 545T , Perylene, rubrene, periflanthene, 2,5,8,11-tetra (tert-butyl) perylene (abbreviation: TBP), 9,10-diphenylanthracene (abbreviation: DPA), 5,12-diphenyltetracene, 4- ( Dicyanomethylene) -2-methyl- [p- (dimethylamino) styryl] -4H-pyran (abbreviation: DCM1), 4- (di Cyanomethylene) -2-methyl-6- [2- (julolidin-9-yl) ethenyl] -4H-pyran (abbreviation: DCM2), 4- (dicyanomethylene) -2,6-bis [p- (dimethylamino) ) Styryl] -4H-pyran (abbreviation: BisDCM) and the like. In addition, bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (picolinate) (abbreviation: FIrpic), bis {2- [3 ′, 5′-bis (trifluoromethyl) ) Phenyl] pyridinato-N, C ^{2 ′} } iridium (picolinate) (abbreviation: Ir (CF ₃ ppy) ₂ (pic)), tris (2-phenylpyridinato-N, C ^{2 ′} ) iridium (abbreviation: Ir (Ppy) ₃ ), bis (2-phenylpyridinato-N, C ^{2 ′} ) iridium (acetylacetonate) (abbreviation: Ir (ppy) ₂ (acac)), bis [2- (2′-thienyl) pyridinato -N, C ^{3 ']} iridium (acetylacetonate) _{(abbreviation: Ir (thp) 2 (acac} )), bis (2-phenylquinolinato--N, C ^2') iridium (acetylacetonate) ( _{Universal: Ir (pq) 2 (acac} )), bis [2- (2'-benzothienyl) pyridinato -N, C ^{3 ']} iridium (acetylacetonate) (abbreviation: Ir (btp) ₂ (acac)), etc. It is also possible to use a compound capable of emitting the phosphorescence.

Further, in the second layer 112, not only the second organic compound that emits light but also other organic compounds may be added. Examples of the organic compound that can be added include TDATA, MTDATA, m-MTDAB, TPD, NPB, DNTPD, TCTA, Alq ₃ , Almq ₃ , BeBq ₂ , BAlq, Zn (BOX) ₂ , and Zn (BTZ) described above. ₂ , BPhen, BCP, PBD, OXD-7, TPBI, TAZ, p-EtTAZ, DNA, t-BuDNA, DPVBi, etc., 4,4′-bis (N-carbazolyl) biphenyl (abbreviation: CBP), 1 , 3,5-tris [4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB) can be used, but is not limited thereto. In addition, the organic compound added in addition to the second organic compound in this way has an excitation energy larger than the excitation energy of the second organic compound in order to efficiently emit the second organic compound, and the second organic compound. It is preferable to add more than the organic compound (by this, concentration quenching of the second organic compound can be prevented). Or as another function, you may show light emission with a 2nd organic compound (Thereby, white light emission etc. are also attained).

  The second inorganic compound may be any inorganic compound as long as it is difficult to quench the light emission of the second organic compound, and various metal halides, metal oxides, and metal nitrides can be used. In particular, a metal oxide of Group 13 or Group 14 of the periodic table is preferable because it is difficult to quench the light emission of the second organic compound, and specifically, aluminum oxide, gallium oxide, silicon oxide, and germanium oxide are preferable. . However, it is not limited to these, Lithium fluoride, calcium fluoride, and magnesium fluoride can also be used.

  Note that the second layer 112 may be formed by stacking a plurality of layers to which a combination of the above-described organic compound and inorganic compound is applied. Moreover, other organic compounds or other inorganic compounds may be further contained.

  Next, materials that can be used for the first electrode 101 and the second electrode 102 are described. The first electrode 101 is preferably made of a material having a high work function (specifically, a material having a work function of 4.5 eV or higher), and the second electrode 102 is made of a material having a low work function (specifically, a material having a work function of 3.5 eV or lower). preferable. However, since the hole injection / transport characteristics of the first layer 111 and the electron injection / transport characteristics of the third layer 113 are excellent, both the first electrode 101 and the second electrode 102 are almost limited in work function. Various materials can be used without being subjected to this.

  At least one or both of the first electrode 101 and the second electrode 102 may be light-transmitting. In that case, a transparent conductive film may be specifically used, and indium tin oxide (ITO), indium zinc oxide (IZO), indium tin oxide added with silicon oxide (ITSO), or the like can be used. In addition, one of the first electrode 101 and the second electrode 102 may be light-shielding (particularly reflective), such as titanium, tungsten, nickel, gold, platinum, silver, aluminum, magnesium, calcium, lithium , And conductive films made of alloys thereof. Further, the first electrode 101 and the second electrode 102 may be formed by stacking a metal thin film such as aluminum, silver, or gold and the above-described transparent conductive film, and serving as a half mirror.

  Note that the light-emitting element of the present invention has various variations by changing types of the first electrode 101 and the second electrode 102. The schematic diagram is shown in FIG. 3 and FIG. In FIGS. 3 and 4, the reference numerals in FIG. 1 are used. Reference numeral 100 denotes a substrate carrying the light emitting element of the present invention.

  FIG. 3 shows a case where the composite layer 103 is configured in the order of the first layer 111, the second layer 112, and the third layer 113 from the substrate 100 side. At this time, the first electrode 101 is made light-transmitting and the second electrode 102 is made light-shielding (particularly reflective) so that light is emitted from the substrate 100 side as shown in FIG. Become. In addition, the first electrode 101 is made light-shielding (particularly reflective) and the second electrode 102 is made light-transmissive so that light is emitted from the opposite side of the substrate 100 as shown in FIG. It becomes. Further, by making both the first electrode 101 and the second electrode 102 light transmissive, light is emitted to both the substrate 100 side and the opposite side of the substrate 100 as shown in FIG. Configuration is also possible.

  FIG. 4 shows a case where the composite layer 103 is configured from the substrate 100 side in the order of the third layer 113, the second layer 112, and the first layer 111. At this time, the first electrode 101 is made light-shielding (particularly reflective), and the second electrode 102 is made light-transmissive so that light is extracted from the substrate 100 side as shown in FIG. . Further, the first electrode 101 is made light-transmitting and the second electrode 102 is made light-shielding (particularly reflective) so that light is extracted from the opposite side of the substrate 100 as shown in FIG. Become. Furthermore, by making both the first electrode 101 and the second electrode 102 light transmissive, light is emitted to both the substrate 100 side and the opposite side of the substrate 100 as shown in FIG. Configuration is also possible.

  As described above, in the light-emitting element of the present invention, the layer sandwiched between the first electrode 101 and the second electrode 102 is entirely composed of the composite layer 103 in which an organic compound and an inorganic compound are combined. It is made up. In addition, by mixing an organic compound and an inorganic compound, a layer having a function of high carrier injection / transport properties that cannot be obtained individually (that is, the first layer 111 and the third layer 113) is obtained. Is a novel organic / inorganic composite light-emitting element. Such a structure is a light-emitting element different from the conventional organic EL element and inorganic EL element as well as the light-emitting element shown in FIG. 2, and therefore the light-emitting element of the present invention will be referred to as a composite electroluminescent device below. It is called a cent element (CEL element).

  Note that the composite layer 103 is a layer in which an organic compound and an inorganic compound are mixed, and various known methods can be used as a formation method thereof. For example, there is a technique in which both an organic compound and an inorganic compound are evaporated by resistance heating and co-evaporated. In addition, while the organic compound is evaporated by resistance heating, the inorganic compound may be evaporated by electron beam (EB) and co-evaporated. Further, there is a method of evaporating the organic compound by resistance heating and simultaneously sputtering the inorganic compound and depositing both at the same time. In addition, the film may be formed by a wet method.

  Similarly, for the first electrode 101 and the second electrode 102, a vapor deposition method using resistance heating, an EB vapor deposition method, a sputtering method, a wet method, or the like can be used.

[Embodiment 2]
In the second embodiment, an aspect of the CEL element of the present invention, which is different from the first embodiment, will be described. The element structure is shown in FIG. In FIG. 5, the reference numerals in FIG. 1 are cited.

  FIG. 5 illustrates a light-emitting element in which a composite layer 103 formed by mixing an organic compound and an inorganic compound is sandwiched between a first electrode 101 and a second electrode 102. The composite layer 103 is illustrated in FIG. As described above, the first layer 111, the second layer 112, the third layer 113, and the fourth layer 114 are included.

  For the first electrode 101, the second electrode 102, the first layer 111, the second layer 112, and the third layer 113, the same structure as each layer in Embodiment 1 (that is, FIG. 1) can be applied. Therefore, the description is omitted. The difference from the first embodiment is that a fourth layer 114 is provided between the third layer 113 and the second electrode 102.

  The fourth layer 114 includes at least a fourth organic compound and a fourth inorganic compound that exhibits an electron accepting property with respect to the fourth organic compound. Accordingly, the fourth organic compound is the same as the first organic compound listed in Embodiment 1, and the fourth inorganic compound is the same as the first inorganic compound listed in Embodiment 1. Can be used. However, the fourth organic compound may be the same as or different from the first organic compound. Moreover, the same thing as a 1st inorganic compound may be used for a 4th inorganic compound, and a different thing may be used for it.

  With such a configuration, as shown in FIG. 5, by applying a voltage, electrons are transferred near the interface between the third layer 113 and the fourth layer 114, and electrons and holes are generated. The third layer 113 transports electrons to the second layer 112, and the fourth layer 114 transports holes to the second electrode 102. That is, the third layer 113 and the fourth layer 114 together serve as a carrier generation layer. In addition, it can be said that the fourth layer 114 has a function of transporting holes to the second electrode 102. Note that a multi-photon light-emitting element can be obtained by stacking the second layer and the third layer again between the fourth layer 114 and the second electrode 102.

  Further, as will be described later in Example 1, the mixed layer (that is, the first layer 111 and the fourth layer 114) of an organic compound and an inorganic compound that exhibits an electron accepting property with respect to the organic compound is extremely High hole injection and transportability. Therefore, the CEL element according to the second embodiment can make both sides of the composite layer 103 very thick as compared with the first embodiment, and can effectively prevent a short circuit of the element. Further, taking FIG. 5 as an example, when the second electrode 102 is formed by sputtering, damage to the second layer 112 in which a light-emitting organic compound is present can be reduced. Furthermore, since the first layer 111 and the fourth layer 114 are made of the same material, both sides of the composite layer 103 are made of the same material, so that an effect of suppressing stress strain can be expected.

  Note that the CEL element according to the second embodiment also has various variations by changing the types of the first electrode 101 and the second electrode 102 as in the first embodiment. The schematic diagram is shown in FIG. 6 and FIG. In FIGS. 6 and 7, the reference numerals in FIG. 5 are cited. Reference numeral 100 denotes a substrate carrying the CEL element of the present invention.

  FIG. 6 shows a case where the composite layer 103 is configured in the order of the first layer 111, the second layer 112, the third layer 113, and the fourth layer 114 from the substrate 100 side. At this time, the first electrode 101 is made light-transmitting and the second electrode 102 is made light-shielding (particularly reflective) so that light is emitted from the substrate 100 side as shown in FIG. Become. In addition, the first electrode 101 is made light-shielding (particularly reflective) and the second electrode 102 is made light-transmissive so that light is emitted from the opposite side of the substrate 100 as shown in FIG. It becomes. Furthermore, by making both the first electrode 101 and the second electrode 102 light transmissive, light is emitted to both the substrate 100 side and the opposite side of the substrate 100 as shown in FIG. Configuration is also possible.

  FIG. 7 illustrates a case where the composite layer 103 is configured in the order of the fourth layer 114, the third layer 113, the second layer 112, and the first layer 111 from the substrate 100 side. At this time, the first electrode 101 is made light-shielding (particularly reflective), and the second electrode 102 is made light-transmissive so that light is extracted from the substrate 100 side as shown in FIG. . Further, the first electrode 101 is made light-transmitting and the second electrode 102 is made light-shielding (particularly reflective) so that light is extracted from the opposite side of the substrate 100 as shown in FIG. 7B. Become. Furthermore, by making both the first electrode 101 and the second electrode 102 light transmissive, light is emitted to both the substrate 100 side and the opposite side of the substrate 100 as shown in FIG. Configuration is also possible.

  Note that the composite layer 103 is a layer in which an organic compound and an inorganic compound are mixed, and various known methods can be used as a formation method thereof. For example, there is a technique in which both an organic compound and an inorganic compound are evaporated by resistance heating and co-evaporated. In addition, while the organic compound is evaporated by resistance heating, the inorganic compound may be evaporated by electron beam (EB) and co-evaporated. Further, there is a method of evaporating the organic compound by resistance heating and simultaneously sputtering the inorganic compound and depositing both at the same time. In addition, the film may be formed by a wet method.

  Similarly, for the first electrode 101 and the second electrode 102, a vapor deposition method using resistance heating, an EB vapor deposition method, a sputtering method, a wet method, or the like can be used.

[Embodiment 3]
In this embodiment mode, a light-emitting device having the CEL element of the present invention in a pixel portion will be described with reference to FIG. 8A is a top view illustrating the light-emitting device, and FIG. 8B is a cross-sectional view taken along line AA ′ in FIG. 8A. 801 indicated by a dotted line is a source side driver circuit, 802 is a pixel portion, and 803 is a gate side driver circuit. Further, reference numeral 804 denotes a sealing substrate, 805 denotes a sealing material, and an inner region 806 surrounded by the sealing material 805 may be a space filled with an inert gas or filled with a solid such as a resin. May be.

  A connection wiring 807 for transmitting signals input to the source side driver circuit 801 and the gate side driver circuit 803 is a video signal, a clock signal, a start signal, and a reset signal from an FPC (flexible printed circuit) 808 serving as an external input terminal. Receive 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 substrate 810. Here, a source side driver circuit 801 which is a driver circuit portion and a pixel portion 802 are shown.

  Note that the source side driver circuit 801 is a CMOS circuit in which an n-channel TFT 823 and a p-channel TFT 824 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 driver integrated type in which a driver circuit is formed over a substrate is shown; however, this is not always necessary, and the driver circuit may be formed outside the substrate.

  The pixel portion 802 is formed of a plurality of pixels including a switching TFT 811, a current control TFT 812, and a first electrode 813 electrically connected to the drain thereof. Note that an insulator 814 is formed to cover an end portion of the first electrode 813. 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 814. For example, in the case where positive photosensitive acrylic is used as a material for the insulator 814, it is preferable that only the upper end portion of the insulator 814 have a curved surface having a curvature radius (0.2 μm to 3 μm). As the insulator 814, 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 can be used.

  A composite layer 815 and a second electrode 816 are formed over the first electrode 813 to form a CEL element 817. As the structures of the first electrode 813, the composite layer 815, and the second electrode 816, the structures of Embodiments 1 and 2 described above may be applied.

  Further, the sealing substrate 804 is bonded to the substrate 810 with the sealant 805, whereby the CEL element 817 is provided in a region 806 surrounded by the substrate 810, the sealing substrate 804, and the sealant 805. Note that the region 806 includes a structure filled with a sealant 805 in addition to a case where the region 806 is filled with an inert gas (nitrogen, argon, or the like).

  Note that an epoxy-based resin is preferably used for the sealant 805. 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 and 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 used for the sealing substrate 804.

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

[Embodiment 4]
In this example, various electric appliances completed using a light emitting device having a CEL element of the present invention will be described.

  The present invention relates to a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio, audio component, etc.), a personal computer, a game machine, a portable information terminal (mobile computer, cellular phone, Portable game machine or electronic book), image reproducing apparatus provided with a recording medium (specifically, an apparatus equipped with a display device capable of reproducing a recording medium such as a digital video disc (DVD) and displaying the image) Etc. Specific examples of these electric appliances are shown in FIG.

  FIG. 9A illustrates a display device, 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 a CEL element of the present invention for the display portion 9103. The display device includes all information display devices such as a computer, a television broadcast receiver, and an advertisement display. Since the CEL element of the present invention has a low driving voltage, a display device with low power consumption can be provided. In addition, since defects in pixels are less likely to occur and changes in luminance with time are small, high-quality images can be displayed over a long period of time.

  FIG. 9B illustrates a personal 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 CEL element of the present invention for the display portion 9203. Since the CEL element of the present invention has a low driving voltage, it can be used for a long time even in a usage form using a battery, particularly in a notebook computer. In addition, since defects in pixels are less likely to occur and changes in luminance with time are small, high-quality images can be displayed over a long period of time.

  FIG. 9C illustrates a mobile computer, which includes a main body 9301, a display portion 9302, a switch 9303, operation keys 9304, an infrared port 9305, and the like. It is manufactured by using a light emitting device having a CEL element of the present invention for the display portion 9302. Since the CEL element of the present invention has a low driving voltage, the power consumption of the mobile computer can be reduced. Thereby, the mobile computer can be used for a long time by one charge. In addition, since the battery built in the mobile computer can be reduced in size, the mobile computer can be reduced in weight.

  FIG. 9D illustrates a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 9401, a housing 9402, a display portion A 9403, a display portion B 9404, and a recording medium (such as a DVD). A reading unit 9405, operation keys 9406, a speaker unit 9407, and the like are included. The display portion A 9403 mainly displays image information, and the display portion B 9404 mainly displays character information. The light-emitting device having the CEL element of the present invention is used for the display portion A 9403 and the display portion B 9404. Note that an image reproducing device provided with a recording medium includes a home game machine and the like. Since the CEL element of the present invention has a low driving voltage, an image reproducing apparatus with low power consumption can be provided. In addition, since defects in pixels are less likely to occur and changes in luminance with time are small, high-quality images can be displayed over a long period of time.

  FIG. 9E illustrates a goggle type display (head mounted display), which includes a main body 9501, a display portion 9502, and an arm portion 9503. It is manufactured by using a light emitting device having a CEL element of the present invention for the display portion 9502. Since the CEL element of the present invention has a low driving voltage, a goggle type display with low power consumption can be provided. In addition, since defects in pixels are less likely to occur and changes in luminance with time are small, high-quality images can be displayed over a long period of time.

  FIG. 9F illustrates a video camera, which includes a main body 9601, a display portion 9602, a housing 9603, an external connection port 9604, a remote control receiving portion 9605, an image receiving portion 9606, a battery 9607, an audio input portion 9608, operation keys 9609, and an eyepiece. Part 9610 and the like. The display device 9602 is manufactured using the light-emitting device having the CEL element of the present invention. Since the CEL element of the present invention has a low driving voltage, the power consumption of the video camera can be reduced. Thus, the video camera can be used for a long time with a single charge. In addition, since the battery built in the video camera can be reduced in size, the weight of the video camera can be reduced.

  Here, FIG. 9G illustrates a cellular phone, which includes a main body 9701, a housing 9702, a display portion 9703, an audio input portion 9704, an audio output portion 9705, operation keys 9706, an external connection port 9707, an antenna 9708, and the like. It is manufactured by using a light emitting device having a CEL element of the present invention for the display portion 9703. Since the CEL element of the present invention has a low driving voltage, the power consumption of the mobile phone can be reduced. Thus, the mobile phone can be used for a long time with a single charge. In addition, since the battery built in the mobile phone can be reduced in size, the mobile phone can be reduced in weight.

  As described above, the applicable range of the light-emitting device having the CEL element of the present invention is so wide that the light-emitting device can be applied to electric appliances in various fields.

  In the present Example 1, the examination example of the combination of an organic compound and an inorganic compound is illustrated about the layer formed by mixing an organic compound and an inorganic compound.

[Film Formation Example 1]
First, a glass substrate is fixed to a substrate holder in a vacuum deposition apparatus. Then, NPB and molybdenum oxide (VI) were put in separate resistance heating evaporation sources, and a mixed film of NPB and molybdenum oxide was formed by a co-evaporation method in a vacuum state. At this time, NPB was evaporated at a film formation rate of 0.4 nm / s, and molybdenum oxide was evaporated in an amount (weight ratio) of 1/4 with respect to NPB. Therefore, the molar ratio is NPB: molybdenum oxide = 1: 1. The film thickness was 50 nm.

  The result of measuring the transmission spectrum of the NPB: molybdenum oxide mixed film thus formed is shown as 1-A in FIG. For comparison, the transmission spectrum of the NPB film (1-B in the figure) and the transmission spectrum of the molybdenum oxide film (1-C in the figure) are also shown.

  As can be seen from FIG. 10, in the mixed film of 1-A, new absorption that was not seen in the single films of NPB or molybdenum oxide was observed (the part circled in the figure). This is because NPB and molybdenum oxide exchange electrons, and it is considered that molybdenum oxide receives electrons from NPB and holes are generated in NPB.

  Therefore, the NPB: molybdenum oxide mixed film formed in the present film formation example 1 can be used as the first layer and / or the fourth layer in the CEL element of the present invention.

[Film Formation Example 2]
The transmission spectrum of an m-MTDAB: molybdenum oxide mixed film produced in the same manner as in Film Formation Example 1 was measured by changing NPB in Film Formation Example 1 to m-MTDAB. A result is shown to 2-A in FIG. For comparison, the transmission spectrum of the m-MTDAB film (2-B in the figure) and the transmission spectrum of the molybdenum oxide film (2-C in the figure) are also shown.

  As can be seen from FIG. 11, in the mixed film of 2-A, new absorption that was not observed in the single film of m-MTDAB or molybdenum oxide was observed (the part circled in the figure). This is because m-MTDAB and molybdenum oxide exchange electrons, and it is considered that molybdenum oxide receives electrons from m-MTDAB and holes are generated in m-MTDAB.

  Therefore, the m-MTDAB: molybdenum oxide mixed film formed in the present film formation example 2 can be used as the first layer and / or the fourth layer in the CEL element of the present invention.

[Film Formation Example 3]
Changing the NPB in Film Formation Example 1 to Alq _3, Alq ₃ was prepared in the same manner as in Film Formation Example 1 were measured the transmission spectrum of molybdenum oxide mixed film. A result is shown to 3-A in FIG. For comparison, the transmission spectrum of the Alq ₃ film (3-B in the figure) and the transmission spectrum of the molybdenum oxide film (3-C in the figure) are also shown.

As can be seen from FIG. 12, the transmission spectrum of the mixed film of 3-A is simply a superposition of the transmission spectrum of Alq ₃ alone (3-B) and the transmission spectrum of molybdenum oxide alone (3-C), and a new absorption is obtained. Did not occur. This indicates that Alq ₃ and molybdenum oxide do not transfer electrons. That is, in this case, molybdenum oxide is not formed level with respect to Alq _3, it can be said that hardly quench the luminescence of Alq _3.

Therefore, the Alq ₃ : molybdenum oxide mixed film formed in the present film formation example 3 can be used as the second layer in the CEL element of the present invention.

  In Example 2, the result of examining the electrical characteristics of a layer formed by mixing an organic compound and an inorganic compound will be described.

  First, a glass substrate on which ITSO is formed to a thickness of 110 nm is prepared. The ITSO surface was covered with an insulating film so that the surface was exposed with a size of 2 mm square.

  Next, the glass substrate is fixed to a substrate holder in the vacuum evaporation apparatus so that the surface on which ITSO is formed is downward. Then, NPB and molybdenum oxide (VI) were put in separate resistance heating evaporation sources, and a mixed film of NPB and molybdenum oxide was formed by a co-evaporation method in a vacuum state. At this time, NPB was evaporated at a film forming rate of 0.4 nm / s, and molybdenum oxide was evaporated in an amount (weight ratio) of 1/2 with respect to NPB. Therefore, the molar ratio is NPB: molybdenum oxide = 1: 2. The film thickness was 50 nm. Furthermore, 150 nm of aluminum (Al) was formed thereon.

FIG. 13 shows the results of examining the voltage-current characteristics of the laminated structure of ITSO / NPB: molybdenum oxide mixed film / Al thus obtained. As shown in FIG. 13, although the curve is slightly convex downward, it can be seen that the voltage-current characteristic is almost a straight line, and the ohmic current is dominant. Therefore, it is considered that there is almost no hole injection barrier with ITSO, suggesting that holes are injected and transported efficiently. The current that flowed when a voltage of 0.5 V was applied was 12.9 mA, the electrode (ITSO) area was 4 mm ² , and the film thickness was 50 nm. Therefore, the resistivity ρ at this time was ρ = (0 0.5 / 0.0129) × (4 × 10 ⁻⁶ ) / (50 × 10 ⁻⁹ ) = 3.1 × 10 ³ [Ωm]. Therefore, it can be said that it is a semiconductor region.

  From the above results, the NPB: molybdenum oxide mixed film has excellent hole injection / transport characteristics and can be used as the first layer and / or the fourth layer in the CEL element of the present invention.

  In Example 3, a specific configuration of the CEL element of the present invention disclosed in Embodiment 1 is illustrated. In the third embodiment, the reference numerals in FIG. 1 are used.

  First, a glass substrate on which ITSO is formed to a thickness of 110 nm is prepared. The formed ITSO acts as the first electrode 101 in this embodiment.

  Next, the glass substrate on which the first electrode 101 is formed is fixed to a substrate holder in the vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed is downward. Then, in a state where NPB and molybdenum oxide (VI) are put in separate resistance heating evaporation sources and are evacuated, a first layer 111 in which NPB and molybdenum oxide are mixed is formed by a co-evaporation method. At this time, NPB is evaporated at a film formation rate of 0.4 nm / s, and molybdenum oxide is evaporated by a quarter amount (weight ratio) with respect to NPB. The film thickness is 120 nm.

Next, the second layer 112 is formed over the first layer 111. In the present embodiment, by co-evaporation of Alq ₃ and molybdenum oxide (VI), to form a second layer 112 which Alq ₃ and molybdenum oxide are mixed. At this time, Alq ₃ is evaporated at a film formation rate of 0.4 nm / s, and molybdenum oxide is evaporated by a quarter amount (weight ratio) with respect to Alq ₃ . The film thickness is 30 nm.

Further, a third layer 113 is formed on the second layer 112. In the present embodiment, by co-evaporation of lithium oxide and Alq _3, to form a third layer 113 that lithium oxide and Alq ₃ were mixed. At this time, Alq ₃ is evaporated at a film formation rate of 0.4 nm / s, and lithium oxide is evaporated in an amount (weight ratio) of 7/100 with respect to Alq ₃ . The film thickness is 10 nm.

  Finally, 150 nm of Al is deposited as the second electrode 102 to obtain the CEL element of the present invention.

  In Example 4, a specific configuration of the CEL element of the present invention disclosed in Embodiment 2 is illustrated. In addition, in the present Example 4, the code | symbol of FIG. 5 is quoted.

  First, a glass substrate on which ITSO is formed to a thickness of 110 nm is prepared. The formed ITSO acts as the first electrode 101 in this embodiment.

  Next, the glass substrate on which the first electrode 101 is formed is fixed to a substrate holder in the vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed is downward. Then, in a state where NPB and molybdenum oxide (VI) are put in separate resistance heating evaporation sources and are evacuated, a first layer 111 in which NPB and molybdenum oxide are mixed is formed by a co-evaporation method. At this time, NPB is evaporated at a film formation rate of 0.4 nm / s, and molybdenum oxide is evaporated by a quarter amount (weight ratio) with respect to NPB. The film thickness is 120 nm.

Next, the second layer 112 is formed over the first layer 111. In the present embodiment, by co-evaporation of Alq ₃ and magnesium fluoride, to form a second layer 112 of Alq ₃ and magnesium fluoride were mixed. At this time, Alq ₃ is evaporated at a film formation rate of 0.4 nm / s, and magnesium fluoride is evaporated in an amount (weight ratio) of 9/100 with respect to Alq ₃ . The film thickness is 30 nm.

Further, a third layer 113 is formed on the second layer 112. In the present embodiment, by co-evaporation of lithium oxide and Alq _3, to form a third layer 113 that lithium oxide and Alq ₃ were mixed. At this time, Alq ₃ is evaporated at a film formation rate of 0.4 nm / s, and lithium oxide is evaporated in an amount (weight ratio) of 7/100 with respect to Alq ₃ . The film thickness is 10 nm.

  Further, a fourth layer 114 is formed over the third layer 113. In this embodiment, similarly to the first layer 111, a fourth layer 114 in which NPB and molybdenum oxide are mixed is formed by a co-evaporation method of NPB and molybdenum oxide. At this time, NPB is evaporated at a film formation rate of 0.4 nm / s, and molybdenum oxide is evaporated by a quarter amount (weight ratio) with respect to NPB. The film thickness is 120 nm.

  Finally, 150 nm of Al is deposited as the second electrode 102 to obtain the CEL element of the present invention.

FIG. 6 illustrates an element structure of a light-emitting element of the present invention. The figure which shows the element structure of the conventional light emitting element. FIG. 4 shows a light emission direction of a light-emitting element of the present invention. FIG. 4 shows a light emission direction of a light-emitting element of the present invention. FIG. 6 illustrates an element structure of a light-emitting element of the present invention. FIG. 4 shows a light emission direction of a light-emitting element of the present invention. FIG. 4 shows a light emission direction of a light-emitting element of the present invention. FIG. 9 illustrates a light-emitting device having a light-emitting element of the present invention. The figure which shows the electric appliance using the light-emitting device of this invention. The figure which shows the transmission spectrum of the film | membrane which mixed the organic compound and the inorganic compound. The figure which shows the transmission spectrum of the film | membrane which mixed the organic compound and the inorganic compound. The figure which shows the transmission spectrum of the film | membrane which mixed the organic compound and the inorganic compound. The figure which shows the voltage-current characteristic of the film | membrane which mixed the organic compound and the inorganic compound.

Explanation of symbols

100 substrate 101 first electrode 102 second electrode 103 composite layer 111 first layer 112 second layer 113 third layer 114 fourth layer 201 first electrode (anode)
202 Second electrode (cathode)
203 Composite layer 211 Hole transport layer 212 Light emitting layer 213 Electron transport layer 801 Source side drive circuit 802 Pixel portion 803 Gate side drive circuit 804 Sealing substrate 805 Seal material 806 Area 807 Connection wiring 808 FPC (flexible printed circuit)
810 Substrate 811 Switching TFT
812 Current control TFT
813 First electrode 814 Insulator 815 Composite layer 816 Second electrode 817 CEL element 823 n-channel TFT
824 p-channel TFT
9101 Case 9102 Support base 9103 Display unit 9104 Speaker unit 9105 Video input terminal 9201 Main body 9202 Case 9203 Display unit 9204 Keyboard 9205 External connection port 9206 Pointing mouse 9301 Main body 9302 Display unit 9303 Switch 9304 Operation key 9305 Infrared port 9401 Main body 9402 Case Body 9403 Display A
9404 Display unit B
9405 Recording medium reading unit 9406 Operation key 9407 Speaker unit 9501 Main unit 9502 Display unit 9503 Arm unit 9601 Main unit 9602 Display unit 9603 Case 9604 External connection port 9605 Remote control receiving unit 9606 Image receiving unit 9607 Battery 9608 Audio input unit 9609 Operation key 9610 Eyepiece Unit 9701 body 9702 housing 9703 display unit 9704 audio input unit 9705 audio output unit 9706 operation key 9707 external connection port 9708 antenna

Claims (20)

A light-emitting element in which a composite layer containing an organic compound and an inorganic compound is sandwiched between a pair of electrodes,
The composite layer includes a first layer, a second layer, a third layer, and a fourth layer that are sequentially stacked.
The first layer includes a first organic compound and a first inorganic compound that exhibits an electron accepting property with respect to the first organic compound,
The second layer includes a second organic compound that emits light and a second inorganic compound,
The third layer includes a third organic compound and a third inorganic compound that exhibits an electron donating property to the third organic compound,
The light emitting element, wherein the fourth layer includes a fourth organic compound and a fourth inorganic compound that exhibits an electron accepting property with respect to the fourth organic compound. Oite to claim 1,
The light-emitting element, wherein the fourth organic compound is a hole-transporting organic compound. In claim 1 or 2 ,
The light-emitting element, wherein the fourth organic compound is an organic compound having an aromatic amine skeleton. In any one of Claims 1 thru | or 3 ,
The light-emitting element, wherein the fourth inorganic compound is a metal oxide. In claim 4 ,
The light-emitting element, wherein the metal oxide is a transition metal oxide of any of Groups 4 to 12 of the periodic table. In claim 4 or 5 ,
The light-emitting element, wherein the metal oxide is any metal oxide selected from the group consisting of vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide. In any one of Claims 1 thru | or 6 ,
The light-emitting element, wherein the first organic compound is a hole-transporting organic compound. In any one of Claims 1 thru | or 7 ,
The light-emitting element, wherein the first organic compound is an organic compound having an aromatic amine skeleton. In any one of Claims 1 thru | or 8 ,
The light-emitting element, wherein the third organic compound is an electron-transporting organic compound. In any one of Claims 1 thru | or 9 ,
The light-emitting element, wherein the third organic compound is a chelate metal complex having a chelate ligand including an aromatic ring, an organic compound having a phenanthroline skeleton, or an organic compound having an oxadiazole skeleton. In any one of Claims 1 thru | or 10 ,
The light-emitting element, wherein the first inorganic compound is a metal oxide. In claim 11 ,
The light-emitting element, wherein the metal oxide is a transition metal oxide of any of Groups 4 to 12 of the periodic table. In claim 11 or 12 ,
The light-emitting element, wherein the metal oxide is any metal oxide selected from the group consisting of vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide. In any one of claims 1 to 1 3,
The light-emitting element, wherein the second inorganic compound is a metal oxide. In claim 14 ,
The light-emitting element, wherein the metal oxide is a metal oxide of Group 13 or Group 14 of the periodic table. In claim 14 or 15 ,
The light-emitting element, wherein the metal oxide is any metal oxide selected from the group consisting of aluminum oxide, gallium oxide, silicon oxide, and germanium oxide. In any one of Claims 1 thru | or 16 ,
The light-emitting element, wherein the third inorganic compound is a metal oxide. In claim 17 ,
The light-emitting element, wherein the metal oxide is an alkali metal oxide, an alkaline earth metal oxide, or a rare earth metal oxide. In claim 17 or 18 ,
The light-emitting element, wherein the metal oxide is lithium oxide or barium oxide. The light emitting device characterized by having a light-emitting element according to any one of claims 1 to 19.