JP4912780B2 - Organometallic complex, light-emitting element, light-emitting device, and electronic device - Google Patents

Description

  The present invention relates to an organometallic complex capable of converting an excited triplet state into light emission, a light-emitting element using the organometallic complex, and a light-emitting device using the light-emitting element.

  A light-emitting element using an organic compound is an element in which a layer containing an organic compound or an organic compound film emits light when an electric field is applied. The light emission mechanism is such that by applying a voltage across an organic compound film between electrodes, electrons injected from the cathode and holes injected from the anode recombine in the organic compound film to form molecular excitons. It is said that when the molecular exciton returns to the ground state, it emits energy and emits light.

  In such a light emitting device, the organic compound film is usually formed as a thin film having a thickness of less than 1 μm. Further, since the organic compound film itself is a self-luminous element that emits light, a backlight as used in a conventional liquid crystal display is not necessary. Accordingly, it is a great advantage that such a light-emitting element can be manufactured to be extremely thin and lightweight. For example, in a light-emitting element having an organic compound film of about 100 to 200 nm, the time from injection of carriers to recombination is about several tens of nanoseconds when considering the carrier mobility of the organic compound film, Even including the process from carrier recombination to light emission, light emission occurs within microseconds. Therefore, one of the features is that the response speed is very fast. Further, since such a light-emitting element is a carrier-injection type light-emitting element, it can be driven with a DC voltage, and noise is hardly generated.

  As described above, a light-emitting element using an organic compound is one of the great advantages that it has a wide variety of emission colors in addition to element characteristics such as thinness, light weight, high-speed response, and direct-current low-voltage driving. The factor is the diversity of the organic compound itself. That is, the flexibility of being able to develop materials of various emission colors by molecular design (for example, introduction of substituents) and the like gives rise to rich colors. It can be said that the largest application field of light-emitting elements utilizing the richness of color is a full-color flat panel display.

The above-described element characteristics such as thinness, light weight, high-speed response, and direct-current low-voltage driving can be said to be suitable characteristics for a flat panel display. In recent years, as an attempt to further increase luminous efficiency, use of a phosphorescent material instead of a fluorescent material has been cited. Light emission from a light-emitting element using an organic compound can be emitted from an excited singlet state (S ^* ) (fluorescence) and emitted from an excited triplet state (T ^* ) (phosphorescence). When used, only light emission (fluorescence) from S ^* contributes.

However, the statistical generation ratio of S ^* and T ^* in the light-emitting element is considered to be S ^* : T ^* = 1: 3 (see, for example, Non-Patent Document 1). Therefore, the theoretical limit of the internal quantum efficiency (ratio of photons generated with respect to injected carriers) in a light emitting device using a fluorescent material is 25% on the basis of S ^* : T ^* = 1: 3. Has been. In other words, in the case of a light emitting element using a fluorescent material, at least 75% of the injected carriers are wasted.

In other words, if it is possible to use light emission from T ^* , that is, phosphorescence, it is considered that the light emission efficiency is improved (simply 3 to 4 times), but general organic compounds emit light from T ^* at room temperature. (Phosphorescence) is not observed, and usually only emission (fluorescence) from S ^* is observed. However, in recent years, light-emitting elements that can convert energy emitted when returning from T ^* to the ground state (hereinafter referred to as “triplet excitation energy”) into light emission have been announced one after another, and the light emission efficiency is high. It is attracting attention (see, for example, Non-Patent Document 2).

  In Document 2, an iridium complex using a dibenzo [f, h] quinoxaline derivative as a ligand is synthesized and used as a light-emitting substance in a light-emitting element. Although the obtained light-emitting element exhibits high luminous efficiency, the emission color is orange red, and red emission with good color purity is not realized.

On the other hand, Non-Patent Document 3 uses a iridium complex having 2,3-diphenylquinoxaline as a ligand, and emits deep red light having a CIE chromaticity coordinate of (x, y) = (0.70, 0.28). Has achieved.
Tetsuo Tsutsui, “Applied Physics Society Organic Molecules / Bioelectronics Subcommittee, 3rd Workshop Text”, P.M. 31 (1993) J. et al. Duane, two others, Advanced Materials (2003), 15, No. 3, FEB5, p. 224-228 Hiroyuki Fujii and 5 others, IEICE TRANS. ELECTRON. , Vol. E87-C, NO. 12 DECEMBER 2004 p. 2119-2121

  However, since the chromaticity coordinates of red in the NTSC (National Television System Committee) standard, which is standard for full-color displays, are (x, y) = (0.67, 0.32), they are disclosed in Non-Patent Document 3. When the iridium complex used is used in a display device, the color reproducibility is poor because the chromaticity coordinates do not match between the transmission side and the reception side that transmit image information. Further, the wavelength obtained from the light emitting element is 675 nm, which is lower in visibility than standard red, and high luminance cannot be achieved.

  It is an object of the present invention to provide a substance capable of emitting red light with excellent visibility, which is closer to the NTSC red chromaticity coordinate (x, y) = (0.67, 0.32). To do.

  As a result of extensive research, the inventor of the present invention emits phosphorescence closer to the red chromaticity coordinate of the NTSC standard when the organometallic complex represented by any one of the general formulas (1) to (3) described below. I found out that I can do it.

One aspect of the present invention is an organometallic complex represented by the general formula (1).

In the general formula (1), R ^{1 to} R ³ represent any one of hydrogen, a halogen group, an acyl group, an alkyl group, an alkoxyl group, an aryl group, a cyano group, and a heterocyclic group. However, at least one of R ^{1 to} R ³ represents an electron-withdrawing substituent. M represents a Group 9 element or a Group 10 element. When M is a Group 9 element, n = 2, and when M is a Group 10 element, n = 1.

One aspect of the present invention is an organometallic complex represented by the general formula (2).

In the general formula (2), R ¹ and R ² represent an electron-withdrawing substituent. M represents a Group 9 element or a Group 10 element. When M is a Group 9 element, n = 2, and when M is a Group 10 element, n = 1.

One aspect of the present invention is an organometallic complex represented by General Formula (3).

  In general formula (3), R represents an electron-withdrawing substituent. M represents a Group 9 element or a Group 10 element. When M is a Group 9 element, n = 2, and when M is a Group 10 element, n = 1.

  In the organometallic complex represented by the general formulas (1) to (3), the electron-withdrawing substituent is preferably any one of a halogen group, a haloalkyl group, and a cyano group. Among halogen groups, a fluoro group having a strong electron withdrawing property is particularly preferable, and among haloalkyl groups, a trifluoromethyl group is particularly preferable.

  In the organometallic complexes represented by the general formulas (1) to (3), the central metal M is preferably a heavy metal, particularly preferably iridium or platinum. Thereby, the heavy atom effect can be obtained. By this heavy atom effect, intersystem crossing is promoted and phosphorescence can be emitted more efficiently.

  One aspect of the present invention is an organometallic complex represented by the general formula (2) in which the electron-withdrawing substituent is a fluoro group, the central metal M is iridium, and n = 2.

  One aspect of the present invention is an organometallic complex represented by the general formula (3) in which the electron-withdrawing substituent is a fluoro group, the central metal M is iridium, and n = 2.

  One embodiment of the present invention is a light-emitting element including an organometallic complex represented by any one of the general formulas (1) to (3) between a pair of electrodes.

  Further, the light-emitting element uses an organometallic complex represented by any one of the general formulas (1) to (3) as a light-emitting substance.

  One embodiment of the present invention is a light-emitting device including a light-emitting element including an organometallic complex represented by any one of the general formulas (1) to (3).

  The organometallic complex or light-emitting element of the present invention can emit red phosphorescence that is closer to the NTSC red chromaticity coordinates and has excellent visibility. In addition, since the light-emitting element of the present invention can emit phosphorescence, its light emission efficiency is good.

  In addition, the light-emitting device of the present invention has excellent visibility by using the organometallic complex of the present invention as a light-emitting substance. Also, since red phosphorescence closer to the NTSC standard red chromaticity coordinate can be emitted, the transmitter side that transmits the signal compliant with the NTSC standard input to the drive circuit and the receiver side that actually emits light. The chromaticity coordinates of red are almost the same. Therefore, a light emitting device that exhibits color reproducibility faithful to input image information can be obtained.

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

(Embodiment 1)
As one embodiment of the present invention, organometallic complexes represented by Structural Formulas (4) to (19) can be given. However, the present invention is not limited to those described here.

  The organometallic complex according to the present invention described above can emit red phosphorescence that is closer to the NTSC red chromaticity coordinates and has excellent visibility.

(Embodiment 2)
The organometallic complex of the present invention can be obtained by coordinating a compound represented by the following general formula (20) to a metal atom by an ortho metalation reaction. Below, the method of synthesize | combining the organometallic complex represented by the said General formula (1) using the ligand represented by this General formula (20) is demonstrated.

In General Formula (20), R ^{1 to} R ³ represent any one of hydrogen, a halogen group, an acyl group, an alkyl group, an alkoxyl group, an aryl group, a cyano group, and a heterocyclic group. However, at least one of R ^{1 to} R ³ represents an electron-withdrawing substituent.

  The ligand (compound A) represented by the general formula (20) is synthesized by, for example, reacting a compound containing benzyl in the skeleton with a compound containing diamine in the skeleton as shown in the synthesis scheme (a-1). be able to.

  Using the ligand of the general formula (20) thus obtained, an organometallic complex used in the present invention is synthesized.

  For example, when synthesizing the organometallic complex of the present invention using iridium as a central metal, a hydrate of iridium chloride is used as a raw material for the central metal, and compound A and iridium chloride are synthesized as shown in the synthesis scheme (a-2). To synthesize Compound B having a structure in which Compound A is coordinated to iridium. The chlorine-crosslinked compound B is also called a binuclear complex. Moreover, the reaction represented by the synthesis scheme (a-2) is referred to as an ortho metalation reaction.

Next, as represented by the synthesis scheme (a-3), the resulting binuclear complex compound B was reacted with a dechlorinating agent such as silver trifluoromethanesulfonate to precipitate silver chloride, The supernatant is reacted with potassium tetrapyrazolyl boronate (abbreviation: Kbpz ₄ ). As described above, the organometallic complex of the present invention represented by the general formula (21) is obtained.

Note that in the synthesis schemes (a-1), (a-2), (a-3), and the general formula (21), R ^{1 to} R ³ are hydrogen, a halogen group, an acyl group, an alkyl group, an alkoxyl group, an aryl Represents any of a group, a cyano group, and a heterocyclic group. However, at least one of R ^{1 to} R ³ represents an electron-withdrawing substituent. The electron-withdrawing substituent is preferably a halogen group, a haloalkyl group, or a cyano group.

  Further, by synthesizing using a salt containing platinum such as potassium tetrachloroplatinate instead of hydrated iridium chloride, an organometallic complex whose central metal is platinum can be obtained.

  The organometallic complex of the present invention synthesized as described above can emit red phosphorescence that is closer to the NTSC red chromaticity coordinate and has excellent visibility.

(Embodiment 3)
An embodiment of a light-emitting element using the organometallic complex of the present invention as a light-emitting substance is described with reference to FIGS.

  FIG. 1 shows a light-emitting element having a light-emitting layer 113 between the first electrode 101 and the second electrode 102. The light emitting layer 113 contains the organometallic complex of the present invention represented by any one of the general formulas (1) to (3).

  In addition to the light-emitting layer 113, a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, an electron injection layer 115, and the like are provided between the first electrode 101 and the second electrode 102. . In these layers, when a voltage is applied so that the potential of the first electrode 101 is higher than the potential of the second electrode 102, holes are injected from the first electrode 101 side and the second electrode 102. They are stacked so that electrons are injected from the side.

  In such a light-emitting element, holes injected from the first electrode 101 side and electrons injected from the second electrode 102 side are recombined in the light-emitting layer 113 and are included in the light-emitting layer. The organometallic complex of the invention is brought into an excited state. The excited organometallic complex emits light when returning to the ground state. Thus, the organometallic complex of the present invention functions as a light emitting substance.

  The light emitting layer 113 may be a layer formed only from the organometallic complex of the present invention, but when concentration quenching occurs, it is a layer made of a substance (host) having an energy gap larger than that of the light emitting substance. A layer mixed so that the light-emitting substance is dispersed therein is preferable. Concentration quenching can be prevented by dispersing and including the organometallic complex of the present invention in the light emitting layer 113. Note that the energy gap is an energy difference between the lowest unoccupied molecular orbital (LUMO) level and the highest occupied molecular orbital (HOMO) level.

There is no particular limitation on a substance used for bringing the organometallic complex of the present invention into a dispersed state, but 2,3-bis (4-diphenylaminophenyl) quinoxaline (abbreviation: TPAQn), 4,4′-bis [N— In addition to a compound having an arylamine skeleton such as (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB), 4,4′-bis (N-carbazolyl) biphenyl (abbreviation: CBP), 4,4 Carbazole derivatives such as', 4 ''-tris (N-carbazolyl) triphenylamine (abbreviation: TCTA), bis [2- (2-hydroxyphenyl) pyridinato] zinc (abbreviation: Znpp ₂ ), bis [2- (2-hydroxyphenyl) benzoxazolato] zinc (abbreviation: ZnBOX), tris (8-quinolinolato) aluminum (abbreviation: Alq _3), such as Metal complex, and the like are preferable. One or two or more substances may be selected from these substances and mixed so that the organometallic complex of the present invention is in a dispersed state. In particular, the organometallic complex of the present invention can emit light more efficiently by mixing the organometallic complex of the present invention with a bipolar substance such as TPAQn described later. Thus, the layer in which a plurality of compounds are mixed can be formed by a co-evaporation method. Here, co-evaporation is a vapor deposition method in which each raw material is vaporized from a plurality of vapor deposition sources provided in one processing chamber, the vaporized raw materials are mixed in a gas phase state, and the mixture is deposited on the object to be processed. Say.

  The anode material for forming the first electrode 101 is not particularly limited, but it is preferable to use a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a high work function (work function of 4.0 eV or more). Specific examples of such an anode material include indium tin oxide (abbreviation: ITO), ITO containing silicon oxide, and a target in which 2 to 20 wt% zinc oxide (ZnO) is mixed with indium oxide. In addition to indium zinc oxide (abbreviation: IZO), gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe) , Cobalt (Co), copper (Cu), palladium (Pd), or a nitride of a metal material (for example, TiN).

  On the other hand, as a material for forming the second electrode 102, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function (a work function of 3.8 eV or less) can be used. Specific examples of such a cathode material include elements belonging to Group 1 or Group 2 of the periodic table, that is, alkali metals such as lithium (Li) and cesium (Cs), magnesium (Mg), calcium (Ca), strontium ( Alkaline earth metals such as Sr) and alloys containing them (Mg: Ag, Al: Li). However, an electron generation layer described later is provided between the second electrode 102 and the light-emitting layer 113 so as to be stacked with the second electrode, so that Al, Ag, ITO, Various conductive materials including the materials mentioned as the material of the first electrode 101 such as ITO containing silicon oxide can be used as the second electrode 102.

  The first electrode 101 and the second electrode 102 are formed by forming the above-described anode material or cathode material, respectively, by vapor deposition, sputtering, or the like. The film thickness is preferably 10 to 500 nm.

Further, a hole transport layer 112 may be provided between the first electrode 101 and the light emitting layer 113 as shown in FIG. Here, the hole transport layer is a layer having a function of transporting holes injected from the first electrode 101 side to the light-emitting layer 113. In this manner, by providing the hole transport layer 112, the distance between the first electrode 101 and the light-emitting layer 113 can be increased. As a result, due to the metal contained in the first electrode 101, It is possible to prevent the light emission from being quenched. The hole transport layer is preferably formed using a substance having a high hole transport property, and particularly preferably formed using a substance having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher. Note that a substance having a high hole-transport property refers to a substance having a higher hole mobility than electrons. Specific examples of a substance that can be used to form the hole-transport layer 112 include 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB), 4, 4′-bis [N- (3-methylphenyl) -N-phenylamino] biphenyl (abbreviation: TPD), 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA), 4,4′-bis {N- [4- ( N, N-di-m-tolylamino) phenyl] -N-phenylamino} biphenyl (abbreviation: DNTPD), 1,3,5-tris [N, N-di (m-tolyl) amino] benzene (abbreviation: m -MTDAB), 4,4 ', 4''- Squirrel (N- carbazolyl) triphenylamine (abbreviation: TCTA), phthalocyanine _{(abbreviation:} H 2 Pc), copper phthalocyanine (abbreviation: CuPc), or vanadyl phthalocyanine (abbreviation: VOPc), and the like. Further, the hole transport layer 112 may be a layer having a multilayer structure formed by combining two or more layers made of the substances described above.

Further, an electron transport layer 114 may be provided between the second electrode 102 and the light emitting layer 113 as shown in FIG. Here, the electron transporting layer is a layer having a function of transporting electrons injected from the second electrode 102 to the light emitting layer 113. In this manner, by providing the electron transport layer 114, the distance between the second electrode 102 and the light-emitting layer 113 can be increased, and as a result, light is emitted due to the metal contained in the second electrode 102. Can be prevented from quenching. The electron transport layer is preferably formed using a substance having a high electron transport property, and particularly preferably formed using a substance having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher. Note that a substance having a high electron-transport property refers to a substance having higher electron mobility than holes. Specific examples of a substance that can be used for forming the electron-transport layer 114 include tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq _3). ), Bis (10-hydroxybenzo [h] -quinolinato) beryllium (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq), bis [2- In addition to metal complexes such as (2-hydroxyphenyl) benzoxazolate] zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ) 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (approximately) Name: PBD), 1,3-bis [5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4- tert-butylphenyl) -4-phenyl-5- (4-biphenylyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2,4-triazole (abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 4,4-bis (5-methylbenzoxa) And sol-2-yl) stilbene (abbreviation: BzOs). Further, the electron transport layer 114 may be a multilayer structure formed by combining two or more layers made of the above-described substances.

Note that the hole transport layer 112 and the electron transport layer 114 may be formed using a bipolar substance in addition to the substances described above. A bipolar substance is the ratio of the mobility of one carrier to the mobility of the other carrier when the mobility of one of the electrons or holes is compared with the mobility of the other carrier. A substance whose value is 100 or less, preferably 10 or less. As a bipolar substance, for example, 2,3-bis (4-diphenylaminophenyl) quinoxaline (abbreviation: TPAQn), 2,3-bis {4- [N- (1-naphthyl) -N-phenylamino] phenyl } -Dibenzo [f, h] quinoxaline (abbreviation: NPDiBzQn) and the like. Among bipolar substances, a substance having a hole or electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or more is preferably used. Alternatively, the hole transport layer 112 and the electron transport layer 114 may be formed using the same bipolar substance.

Further, a hole injection layer 111 may be provided between the first electrode 101 and the hole transport layer 112 as shown in FIG. The hole injection layer 111 is a layer having a function of assisting injection of holes from the first electrode 101 to the hole transport layer 112. By providing the hole injection layer 111, the difference in ionization potential between the first electrode 101 and the hole transport layer 112 is reduced, and holes are easily injected. The hole injection layer 111 has a lower ionization potential than the substance forming the hole transport layer 112 and a higher ionization potential than the substance forming the first electrode 101, or the hole transport layer 112. It is preferable to use a substance whose energy band is bent when it is provided as a 1 to 2 nm thin film between the first electrode 101 and the first electrode 101. Specific examples of a substance that can be used to form the hole-injecting layer 111 include phthalocyanine-based compounds such as phthalocyanine (abbreviation: H ₂ Pc) and copper phthalocyanine (CuPC), or poly (ethylenedioxythiophene) / Examples thereof include a polymer such as a poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS). That is, the hole injection layer 111 can be formed by selecting a material whose ionization potential in the hole injection layer 111 is relatively smaller than the ionization potential in the hole transport layer 112.

  Further, an electron injection layer 115 may be provided between the second electrode 102 and the electron transport layer 114 as shown in FIG. Here, the electron injection layer 115 is a layer having a function of assisting injection of electrons from the second electrode 102 to the electron transport layer 114. By providing the electron injection layer 115, the difference in electron affinity between the second electrode 102 and the electron transport layer 114 is reduced, and electrons are easily injected. The electron injection layer 115 is a substance having a higher electron affinity than the substance forming the electron transport layer 114 and a lower electron affinity than the substance forming the second electrode 102, or the electron transport layer 114 and the second transport layer 114. It is preferable to use a substance whose energy band is bent when it is provided as a 1 to 2 nm thin film between the electrode 102 and the electrode 102. Specific examples of a substance that can be used to form the electron injection layer 115 include alkali metal or alkaline earth metal, alkali metal fluoride, alkaline earth metal fluoride, alkali metal oxide, and alkaline earth. Examples thereof include inorganic substances such as metal oxides. In addition to inorganic materials, materials that can be used to form the electron transport layer 114 such as BPhen, BCP, p-EtTAZ, TAZ, and BzOs are also selected as appropriate to form the electron injection layer 115. Can be used. That is, the electron injecting layer 115 can be formed by selecting a substance whose electron affinity in the electron injecting layer 115 is relatively larger than that in the electron transporting layer 114.

  In the light-emitting element of the present invention described above, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115 are formed by an evaporation method, an inkjet method, or a coating method, respectively. Or any other method.

  Further, a hole generation layer may be provided instead of the hole injection layer 111, or an electron generation layer may be provided instead of the electron injection layer 115.

  Here, the hole generation layer is a layer that generates holes. A hole generating layer is prepared by mixing at least one substance selected from substances having a higher mobility of holes than electrons and bipolar substances, and a substance having electron acceptability with respect to these substances. Can be formed. Here, as a substance having a higher mobility of holes than electrons, a substance similar to the substance that can be used to form the hole-transport layer 112 can be used. In addition, the bipolar substance described above such as TPAQn can also be used for the bipolar substance. Further, among substances having a higher mobility of holes than electrons and bipolar substances, it is particularly preferable to use a substance containing triphenylamine in the skeleton. By using a substance containing triphenylamine in the skeleton, holes are more easily generated. As the substance exhibiting electron accepting properties, it is preferable to use a metal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide, or rhenium oxide. Since such a hole generation layer does not increase the driving voltage even when it is thickened, an optical design utilizing the microcavity effect or the light interference effect is performed by adjusting the film thickness of the hole generation layer. be able to. Therefore, a high-quality light-emitting element with excellent color purity and a small color change depending on the viewing angle can be manufactured. In addition, a film thickness that prevents the first electrode 101 and the second electrode 102 from being short-circuited due to the unevenness generated during the film formation on the surface of the first electrode 101 and the minute residue remaining on the electrode surface is selected. Can do.

The electron generating layer is a layer that generates electrons. The electron generating layer is formed by mixing at least one substance selected from substances having higher electron mobility than holes and bipolar substances, and a substance exhibiting an electron donating property with respect to these substances. Can be formed. Here, as a substance having higher electron mobility than holes, a substance similar to the substance that can be used to form the electron-transport layer 114 can be used. In addition, the bipolar substance described above such as TPAQn can also be used for the bipolar substance. Moreover, as the substance exhibiting electron donating property, a substance selected from alkali metals and alkaline earth metals, specifically, lithium (Li), calcium (Ca), sodium (Na), potassium (K), Magnesium (Mg) or the like can be used. Further, alkali metal oxides or alkaline earth metal oxides, alkali metal nitrides, alkaline earth metal nitrides, etc., specifically lithium oxide (Li ₂ O), calcium oxide (CaO), sodium oxide At least one substance selected from (Na ₂ O), potassium oxide (K ₂ O), and magnesium oxide (MgO) can also be used as the substance exhibiting electron donating properties. Moreover, it is also possible to use alkali metal fluorides, alkaline earth metal fluorides, specifically fluorides such as lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF ₂ ). .

  Since the light-emitting element of the present invention as described above uses the organometallic complex of the present invention, it can emit red phosphorescence excellent in luminous sensitivity, which is closer to the NTSC standard red chromaticity coordinate. . In addition, since the light-emitting element of the present invention can emit phosphorescence, its light emission efficiency is good.

(Embodiment 4)
The light emitting device of the present invention may have a plurality of light emitting layers. For example, white light can be obtained by providing a plurality of light emitting layers and mixing light emitted from the respective light emitting layers. In this embodiment, such a light-emitting element will be described with reference to FIGS.

  In FIG. 2, a first light-emitting layer 213 and a second light-emitting layer 215 are provided between the first electrode 201 and the second electrode 202. A spacing layer 214 is preferably provided between the first light-emitting layer 213 and the second light-emitting layer 215.

  When a voltage is applied so that the potential of the second electrode 202 is higher than the potential of the first electrode 201, a current flows between the first electrode 201 and the second electrode 202, and the first light emitting layer In 213, the second light emitting layer 215, or the spacing layer 214, holes and electrons are recombined. Note that excitation energy generated by recombination in the spacing layer 214 moves from the spacing layer 214 to each of the first light-emitting layer 213 and the second light-emitting layer 215, and the first energy included in the first light-emitting layer 213. And the second luminescent material contained in the second luminescent layer 215 are brought into an excited state. The first light-emitting substance and the second light-emitting substance that are in the excited state emit light when returning to the ground state.

The first light-emitting layer 213 includes perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4,4′-bis [2-diphenylvinyl] biphenyl (abbreviation: DPVBi), 4,4′-bis [2- (N-ethylcarbazol-3-yl) vinyl] biphenyl (abbreviation: BCzVBi), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq ), Bis (2-methyl-8-quinolinolato) -chlorogallium (abbreviation: Gamq ₂ Cl), and bis [2- (3,5-bis (trifluoromethyl) phenyl) pyridinato-N, C ^{2 ']} iridium (III) picolinate _{(abbreviation: Ir (CF 3 ppy) 2} (pic)), bis [2- (4,6-difluorophenyl) pyridinato N, C ^{2 ']} iridium (III) acetylacetonate (abbreviation: FIr (acac)), bis [2- (4,6-difluorophenyl) pyridinato -N, C ^2'] iridium (III) picolinate (abbreviation: A first light-emitting substance typified by a phosphorescent substance such as FIr (pic)) is included, and light emission having an emission spectrum peak at 450 to 510 nm can be obtained from the first light-emitting layer 213. The second light-emitting layer 215 includes the organometallic complex of the present invention represented by any one of the general formulas (1) to (3) so as to function as a second light-emitting substance. From the second light emitting layer 215, red phosphorescence with excellent visibility close to the NTSC standard red chromaticity coordinate is obtained. Then, the emission color from the first emission layer 213 and the emission color from the second emission layer 215 are emitted to the outside through one or both of the first electrode 201 and the second electrode 202. To do. Each light emitted to the outside is visually mixed and visually recognized as white light.

The first light-emitting layer 213 is a state where a light-emitting substance capable of emitting light of 450 to 510 nm is dispersed in a layer made of a substance (first host) having an energy gap larger than that of the light-emitting substance. It is preferably a layer made of a light-emitting substance that is contained or can emit light of 450 to 510 nm. As the first host, NPB, CBP, TCTA, Znpp ₂ , ZnBOX, 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 9,10-di (2-naphthyl) -2- Tert-butylanthracene (abbreviation: t-BuDNA) or the like can be used. In the second light-emitting layer 215, the organometallic complex of the present invention is dispersed in a layer made of a substance (second host) having an energy gap larger than that of the organometallic complex of the present invention. It is preferable that it is the layer contained by. As the second host, TPAQn, NPB, CBP, TCTA, Znpp ₂ , ZnBOX, Alq ₃ or the like can be used. In the spacing layer 214, energy generated by recombination in the first light-emitting layer 213, the second light-emitting layer 215, or the spacing layer 214 can move to both the first light-emitting layer 213 and the second light-emitting layer 215. In addition, it is preferable that the first light emitting layer 213 and the second light emitting layer 215 are formed so as to have a function for preventing energy from being transferred to only one of the first light emitting layer 213 and the second light emitting layer 215. Specifically, the spacing layer 214 can be formed using TPAQn, NPB, CBP, TCTA, Znpp ₂ , ZnBOX, or the like. As described above, the provision of the spacing layer 214 prevents a problem that the light emission intensity of only one of the first light-emitting layer 213 and the second light-emitting layer 215 is increased and white light emission cannot be obtained. Can do.

  Note that there is no particular limitation on the light-emitting substance contained in the first light-emitting layer 213.

  In addition, as illustrated in FIG. 2, an electron transport layer 212 or an electron injection layer 211 may be provided between the first light-emitting layer 213 and the first electrode 201. In addition, a hole transport layer 216 and a hole injection layer 217 may be provided between the second light-emitting layer 215 and the second electrode 202. Note that those described in Embodiment Mode 3 can be used as a material for forming these layers.

  In this embodiment mode, a light-emitting element provided with two light-emitting layers as shown in FIG. 2 is described. However, the number of light-emitting layers is not limited to two. For example, three layers may be used. Good. And what is necessary is just to be visually recognized as white combining the light emission from each light emitting layer.

  In addition to the light-emitting element described with reference to FIG. 2, a light-emitting element as illustrated in FIG. 3 may be used. The light-emitting element in FIG. 3 includes a first light-emitting layer 313 and a second light-emitting layer 318 between the first electrode 301 and the second electrode 302, and the first light-emitting layer 313 and the second light-emitting layer 318 are provided. Between the second light emitting layer 318, a first layer 315 and a second layer 316 are provided.

  The first layer 315 is a layer that generates holes, and the second layer 316 is a layer that generates electrons. When a voltage was applied so that the potential of the second electrode 302 was higher than the potential of the first electrode 301, electrons injected from the first electrode 301 and injected from the first layer 315 The holes are recombined in the first light-emitting layer 313, and the light-emitting substance contained in the first light-emitting layer 313 emits light. Further, the holes injected from the second electrode 302 and the electrons injected from the second layer 316 are recombined in the second light-emitting layer 318, and the light-emitting substance contained in the second light-emitting layer 318 emits light. To do.

The first light-emitting layer 313 includes a fluorescent material such as perylene, TBP, DPVBi, BCzVBi, BAlq, and Gamq ₂ Cl, Ir (CF ₃ ppy) ₂ (pic), FIr (acac), FIr (pic), and the like. A light-emitting substance typified by a phosphorescent substance is contained, and light emission having an emission spectrum peak at 450 to 510 nm can be obtained. The second light-emitting layer 318 includes the organometallic complex of the present invention so as to function as a light-emitting substance, and the second light-emitting layer 318 has a view closer to the NTSC standard red chromaticity coordinate. Red phosphorescence with excellent sensitivity can be obtained. Light emission from the first light-emitting layer 313 and light emission from the second light-emitting layer 318 are emitted from one or both of the first electrode 301 and the second electrode 302. And the light emission from both light emitting layers is visually mixed and visually recognized as white light.

  In the second light-emitting layer 318, it is preferable that the organometallic complex of the present invention is contained dispersedly in the second host as described above. In the first light-emitting layer 313, the light-emitting substance is preferably dispersed in the first host described above.

The first layer 315 is preferably a layer including a substance having a property of transporting more holes than electrons and a substance having an electron accepting property with respect to the substance. As the substance having a higher hole-transport property than electrons, the same substance as that used for forming the hole-transport layer described above may be used. In addition, as a substance having an electron accepting property with respect to a substance having a higher hole-transport property than electrons, molybdenum oxide, vanadium oxide, 7,7,8,8-tetracyanoquinodimethane (abbreviation: TCNQ) 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (abbreviation: F ₄ -TCNQ) or the like can be used.

  The second layer 316 is preferably a layer including a substance having an electron transport property higher than that of holes and a substance that exhibits an electron donating property with respect to the substance. As the substance having a property of transporting electrons higher than that of holes, the same substance as that used for forming the above-described electron transport layer may be used. In addition, as a substance exhibiting an electron donating property with respect to a substance having a higher electron transportability than holes, alkali metals such as lithium and cesium, alkaline earth metals such as magnesium and calcium, and rare earth metals such as erbium and ytterbium, etc. Can be used.

  In addition, as illustrated in FIG. 3, an electron transport layer 312 or an electron injection layer 311 may be provided between the first light-emitting layer 313 and the first electrode 301. In addition, a hole-transport layer 314 may be provided between the first light-emitting layer 313 and the first layer 315. Further, a hole transport layer 319 or a hole injection layer 320 may be provided between the second light-emitting layer 318 and the second electrode 302. In addition, an electron-transport layer 317 may be provided between the second light-emitting layer 318 and the second layer 316.

  Further, in this embodiment mode, a light-emitting element provided with two light-emitting layers as shown in FIG. 3 is described, but the number of light-emitting layers is not limited to two, for example, three layers. May be. And what is necessary is just to be visually recognized as white combining the light emission from each light emitting layer.

(Embodiment 5)
An embodiment of a light-emitting element using the organometallic complex of the present invention as a sensitizer will be described with reference to FIGS.

  FIG. 4 illustrates a light-emitting element having a light-emitting layer 413 between the first electrode 401 and the second electrode 402. In the light emitting layer 413, the organometallic complex of the present invention represented by any one of the general formulas (1) to (3) and a fluorescent material capable of emitting light having a longer wavelength than the organometallic complex of the present invention. And are included. Note that a fluorescent material is a substance that emits fluorescence when returning from an excited state to a ground state.

  In such a light-emitting element, holes injected from the first electrode 401 and electrons injected from the second electrode 402 are recombined in the light-emitting layer 413 to bring the fluorescent material into an excited state. The excited fluorescent material emits light when returning to the ground state. At this time, the organometallic complex of the present invention acts as a sensitizer for the fluorescent material, and amplifies the number of singlet excited states of the fluorescent material. As described above, a light-emitting element with high emission efficiency can be obtained by using the organometallic complex of the present invention as a sensitizer. Note that in the light-emitting element of this embodiment mode, the first electrode 401 functions as an anode and the second electrode 402 functions as a cathode.

  Here, there is no particular limitation on the light-emitting layer 413, but the organic metal complex and the fluorescent material of the present invention are in a layer formed of a substance (host) having an energy gap larger than the energy gap of the organometallic complex of the present invention. It is preferable that the layer is dispersed and contained.

  The fluorescent material is not particularly limited, and compounds exhibiting red to infrared light emission such as magnesium phthalocyanine and phthalocyanine are preferable. There is no particular limitation on the substance used for dispersing the organometallic complex and the fluorescent material of the present invention, and the substance described in Embodiment 3 is used for bringing the organometallic complex to a dispersed state. The substance etc. which can be used can be used.

  There is no particular limitation on the first electrode 401 and the second electrode 402, and the same materials as the first electrode 101 and the second electrode 102 described in Embodiment 3 can be used.

  In addition, a hole injection layer 411, a hole transport layer 412, and the like may be provided between the first electrode 401 and the light-emitting layer 413 as illustrated in FIG. Further, an electron transport layer 414, an electron injection layer 415, or the like may be provided between the second electrode 402 and the light-emitting layer 413.

  The hole injection layer 411, the hole transport layer 412, the electron transport layer 414, and the electron injection layer 415 are the hole injection layer 111, the hole transport layer 112, the electron transport layer 114, and the electrons described in Embodiment 3, respectively. The same material as the injection layer 115 can be used. The light-emitting element of this embodiment may be provided with a hole injection layer 411, a hole transport layer 412, an electron transport layer 414, another functional layer having a function different from that of the electron injection layer 415, or the like.

  The light-emitting element described above is obtained by using the organometallic complex of the present invention as a sensitizer.

(Embodiment 6)
In this embodiment, a light-emitting device to which the present invention is applied 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 the line AA ′ in FIG. 5A (a cross-sectional view cut along AA ′). In each of FIGS. 5A and 5B, the corresponding components are denoted by the same reference numerals. Reference numeral 500 denotes a substrate, reference numeral 501 indicated by a dotted line denotes a driver circuit portion (source side driver circuit), 502 denotes a pixel portion, and 503 denotes a driver circuit portion (gate side driver circuit). Further, reference numeral 504 denotes a sealing substrate, and 505 denotes a sealing material. An inner side surrounded by the sealing material 505 is a space 506.

  Note that reference numeral 507 denotes wiring for transmitting a signal input to the source side driver circuit 501 or the gate side driver circuit 503, and a video signal, a clock signal, and a start signal from an FPC (flexible printed circuit) 508 serving as an external input terminal. Receive signals, reset signals, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light emitting device of the present invention includes not only the light emitting device main body but also a state in which an FPC or 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 500. 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 formed of a CMOS circuit in which an n-channel thin film transistor 521 and a p-channel thin film transistor 522 are combined. Further, the thin film transistor that forms the driving circuit may be formed using a known CMOS circuit, PMOS circuit, or NMOS circuit. Further, in this embodiment mode, a driver integrated type in which a drive circuit is formed on a substrate is shown; however, it is not always necessary and the drive circuit can be formed outside.

  The pixel portion 502 is formed by a plurality of pixels including a switching thin film transistor 511, a current control thin film transistor 512, and a first electrode 513 electrically connected to a drain thereof. Note that an insulator 514 is formed so as to cover an end portion of the first electrode 513.

  In order to improve the formation of the layer 515 containing a light-emitting substance to be formed later, the upper end or the lower end, or the upper and lower ends of the insulator 514 may be formed to have a curved surface having a curvature. preferable. 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). As the insulator 514, 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. Furthermore, the material of the insulator 514 is not limited to an organic material, and an inorganic material such as silicon oxide or silicon oxynitride can also be used.

  Further, a layer 515 containing a light-emitting substance and a second electrode 516 are formed over the first electrode 513.

  A light-emitting element 517 including the first electrode 513, the layer 515 containing a light-emitting substance, and the second electrode 516 is a light-emitting element including the organometallic complex of the present invention. If the layer 515 containing a light-emitting substance has a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3), There is no particular limitation. Note that each of the materials described in Embodiment 3 can be selected as appropriate for the first electrode 513, the layer 515 containing a light-emitting substance, and the second electrode 516.

  Further, the sealing substrate 504 is bonded to the substrate 500 with the sealing material 505, whereby the light-emitting element 517 is provided in the space 506 surrounded by the substrate 500, the sealing substrate 504, and the sealing material 505. . Note that the space 506 includes a structure filled with a sealant 505 in addition to a case where the space is filled with an inert gas (nitrogen, argon, or the like).

  An epoxy 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 can be manufactured.

  Note that in the case where each of the first electrode 513 and the second electrode 516 is formed using a light-transmitting substance, light emission can be extracted from both the first electrode 513 side and the second electrode 516 side. it can. In addition, in the case where only the second electrode 516 is formed using a light-transmitting substance, light emission can be extracted only from the second electrode 516 side. In this case, the first electrode 513 is preferably made of a material with high reflectivity, or a film (reflective film) made of a material with high reflectivity is provided below the first electrode 513. Further, in the case where only the first electrode 513 is formed using a light-transmitting substance, light emission can be extracted only from the first electrode 513 side. In this case, it is preferable that the second electrode 516 is made of a material having high reflectivity or a reflective film is provided above the second electrode 516.

  The light-emitting element 517 is formed by stacking a layer 515 containing a light-emitting substance so that the light-emitting element 517 operates when a voltage is applied so that the potential of the second electrode 516 is higher than the potential of the first electrode 513. Alternatively, a layer 515 containing a light-emitting substance may be stacked so as to operate when a voltage is applied so that the potential of the second electrode 516 is lower than the potential of the first electrode 513. May be.

  The light-emitting device of the present invention has excellent visibility by using the organometallic complex of the present invention as a light-emitting substance. Moreover, since red phosphorescence closer to the NTSC standard red chromaticity coordinate can be emitted, on the transmitting side for transmitting a signal compliant with the NTSC standard inputted to the drive circuit and on the passive side for actually emitting light. The chromaticity coordinates of red are almost the same. Therefore, a display device that exhibits color reproducibility faithful to input image information can be obtained.

  In this embodiment, an active light-emitting device that controls driving of a light-emitting element using a transistor has been described. However, passive light-emitting that drives a light-emitting element without providing a driving element such as a thin film transistor in each pixel. It may be a device.

  This embodiment can be freely combined with Embodiments 1 to 5 and Example 1 described later.

(Embodiment 7)
In this embodiment mode, a passive light-emitting device to which the present invention is applied will be described with reference to FIGS. FIGS. 11A and 11B are a perspective view and a top view, respectively, of a passive light emitting device to which the present invention is applied. Note that FIG. 11A is a perspective view of a portion surrounded by a dotted line 808 in FIG. In each of FIGS. 11A and 11B, the corresponding components are denoted by the same reference numerals. In FIG. 11A, a plurality of first electrodes 802 are provided in parallel over the first substrate 801. Each end portion of the first electrode 802 is covered with a partition wall layer 803. The end portion of the first electrode 802 located closest to the first electrode 802 is covered with the partition wall layer 803. In FIG. 11A, the first electrode 802 provided on the first substrate 801 and the partition wall are provided. In order to make it easy to understand the state in which the layer 803 is arranged, it is not shown. A plurality of second electrodes 805 are provided in parallel above the first electrode 802 so as to intersect the first electrode 802. Note that a layer 804 containing a light-emitting substance is provided between the first electrode 802 and the second electrode 805. A portion where the first electrode 802 and the second electrode 805 intersect constitute a light-emitting element of the present invention in which a layer 804 containing a light-emitting substance is sandwiched between the electrodes. If the layer 804 containing a light-emitting substance has a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3), There is no particular limitation. Note that each of the materials described in Embodiment 3 can be selected as appropriate for the first electrode 802, the light-emitting substance layer 804, and the second electrode 805. A second substrate 809 is provided over the second electrode 805.

  As shown in FIG. 11B, the first electrode 802 is connected to the first driver circuit 806, and the second electrode 805 is connected to the second driver circuit 807. Then, the light emitting element of the present invention selected by signals from the first drive circuit 806 and the second drive circuit 807 emits light. Light emission is extracted to the outside through the first electrode 802 and / or the second electrode 805. The light emitted from the plurality of light emitting elements is combined to display an image. Note that in FIG. 11B, the partition layer 803 and the second substrate 809 are not illustrated for easy understanding of the arrangement of the first electrode 802 and the second electrode 805.

  In the case where both the first electrode 802 and the second electrode 805 are formed using a light-transmitting substance, light emission can be extracted from both the first electrode 802 side and the second electrode 805 side. In addition, in the case where only the second electrode 805 is formed using a light-transmitting substance, light emission can be extracted only from the second electrode 805 side. In this case, the first electrode 802 is preferably formed using a material with high reflectivity, or a film (reflective film) made of a material with high reflectivity is provided below the first electrode 802. In addition, in the case where only the first electrode 802 is formed using a light-transmitting substance, light emission can be extracted only from the first electrode 802 side. In this case, it is preferable that the second electrode 805 be made of a material having high reflectance, or a reflective film be provided above the second electrode 805. The partition layer 803 can be formed using a material similar to that of the insulator 514 described in Embodiment 6.

  The light-emitting device of the present invention has excellent visibility by using the organometallic complex of the present invention as a light-emitting substance. Moreover, since red phosphorescence closer to the NTSC standard red chromaticity coordinate can be emitted, on the transmitting side for transmitting a signal compliant with the NTSC standard inputted to the drive circuit and on the passive side for actually emitting light. The chromaticity coordinates of red are almost the same. Therefore, a display device that exhibits color reproducibility faithful to input image information can be obtained.

  This embodiment can be freely combined with Embodiments 1 to 5 and Example 1 described later.

(Embodiment 8)
In this embodiment, various electronic devices completed using a light-emitting device having the light-emitting element of the present invention will be described. The organometallic complex included in the light-emitting element of the present invention can emit red phosphorescence that is closer to the NTSC red chromaticity coordinate and has excellent visibility. Therefore, the light emitting device of the present invention is excellent in visibility. In addition, since the chromaticity coordinates of red are substantially the same on the transmission side that transmits a signal that conforms to the NTSC standard and is input to the drive circuit, and the passive side that actually emits light, A light emitting device exhibiting faithful color reproducibility can be obtained.

  As an electronic device manufactured using the light emitting device of the present invention, a television, 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 notebook type Personal computer, game device, portable information terminal (mobile computer, cellular phone, portable game machine, electronic book, etc.), image playback device equipped with a recording medium (specifically, a recording medium such as a digital video disc (DVD)) For example, a device provided with a display device capable of reproducing and displaying the image. Some specific examples of electronic devices will be described with reference to FIGS. The electronic apparatus using the light emitting device of the present invention is not limited to these specific examples.

  FIG. 6A illustrates a display device, which includes a housing 600, a support base 601, a display portion 602, a speaker portion 603, a video input terminal 604, and the like. The display device 602 is manufactured using a light-emitting device formed using the present invention. The display device includes all information display devices such as a personal computer, a TV broadcast reception, and an advertisement display.

  The display portion 602 is provided with the light-emitting element of the present invention. The layer containing a light-emitting substance included in the light-emitting element includes a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3). Therefore, by using the light-emitting element of the present invention, a display device having excellent visibility and faithful color reproducibility to input image information can be obtained.

  FIG. 6B illustrates a laptop personal computer, which includes a main body 610, a housing 611, a display portion 612, a keyboard 613, an external connection port 614, a pointing mouse 615, and the like.

  The display portion 612 is provided with the light-emitting element of the present invention. The layer containing a light-emitting substance included in the light-emitting element includes a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3). Therefore, by using the light-emitting element of the present invention, a notebook personal computer that has excellent visibility and faithful color reproducibility to input image information can be obtained.

  FIG. 6C illustrates a video camera, which includes a main body 620, a display portion 621, a housing 622, an external connection port 623, a remote control receiving portion 624, an image receiving portion 625, a battery 626, an audio input portion 627, operation keys 628, and an eyepiece. Part 629 and the like.

  The display portion 621 is provided with the light-emitting element of the present invention. The layer containing a light-emitting substance included in the light-emitting element includes a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3). Therefore, by using the light-emitting element of the present invention, a video camera having excellent visibility and faithful color reproducibility with respect to input image information can be obtained.

  FIG. 6D illustrates a mobile phone, which includes a main body 630, a housing 631, a display portion 632, an audio input portion 633, an audio output portion 634, operation keys 635, an external connection port 636, an antenna 637, and the like.

  The display portion 632 is provided with the light-emitting element of the present invention. The layer containing a light-emitting substance included in the light-emitting element includes a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3). Therefore, by using the light-emitting element of the present invention, a mobile phone that has excellent visibility and exhibits color reproducibility faithful to input image information can be obtained.

  FIG. 6E illustrates a digital camera, which includes a main body 640, a display portion 641, a shutter 642, operation keys 643, an antenna 644, an imaging portion, and the like. Note that FIG. 6E is a view from the display portion 641 side, and the imaging portion is not shown.

  The digital camera of the present invention may cause the display unit 641 to function as a display medium such as a television receiver by receiving a signal such as a video signal or an audio signal from the antenna 644. Note that speakers, operation switches, and the like in the case of functioning as a display medium may be provided as appropriate.

  Note that the display portion 641 is provided with the light-emitting element of the present invention. The layer containing a light-emitting substance included in the light-emitting element includes a light-emitting layer having at least one of the organometallic complexes represented by the general formulas (1) to (3). Therefore, by using the light-emitting element of the present invention, a digital camera having excellent visibility and faithful color reproducibility with respect to input image information can be obtained.

  As described above, the applicable range of the present invention is extremely wide and can be used for display devices in various fields. In addition, the electronic device of this embodiment can be appropriately combined with any structure of Embodiments 1 to 7 and Example 1 described later.

  A synthesis example of the organometallic complex of the present invention will be described. However, the present invention is not limited to the organometallic complexes of the synthesis examples shown below.

<< Synthesis Example 1 >>
In this synthesis example, bis [2,3-bis (4-fluorophenyl) quinoxalinato] (tetravirazolylboronate) iridium (III) (abbreviation: Ir (fdpq) ₂ (bpz) represented by the structural formula (5) is used. ₄ )) Synthesis example.

<Step 1: Synthesis of Ligand (abbreviation: Hfdpq)>
First, 3.71 g of 4,4′-difluorobenzyl and 1.71 g of o-phenylenediamine were refluxed in a chloroform solvent for 6 hours. The reaction solution cooled to room temperature was washed with 1 mol / L hydrochloric acid and then with saturated saline, and then dried over magnesium sulfate. By distilling off the solvent, a ligand 2,3-bis- (4-fluorophenyl) quinoxaline (abbreviation: Hfdpq) was obtained (pale yellow powder, yield 99%). Recrystallization was performed using a chloroform solvent. A synthesis scheme (b-1) of Step 1 is shown below.

<Step 2: Synthesis of binuclear complex (abbreviation: [Ir (fdpq) ₂ Cl] ₂ )>
First, 3.61 g of ligand Hfdpq and 1.35 g of iridium chloride (IrCl ₃ · HCl · H ₂ O) were mixed in a mixed atmosphere of 30 ml of 2-ethoxyethanol and 10 ml of water under a nitrogen atmosphere. By refluxing for 17 hours, a binuclear complex (abbreviation: [Ir (fdpq) ₂ Cl] ₂ ) was obtained (brown powder, yield 99%). A synthesis scheme (b-2) of Step 2 is shown below.

<Step 3: Synthesis of Organometallic Complex of the Present Invention (abbreviation: Ir (fdpq) ₂ (bpz ₄ ))>
1.08 g of [Ir (fdpq) ₂ Cl] ₂ obtained above was stirred in a solvent of 40 ml of dichloromethane, and 0.40 g of silver trifluoromethanesulfonate dissolved in 40 ml of methanol was added dropwise and stirred at room temperature for 2 hours. did. Centrifugation was performed on the obtained suspension solution, and the supernatant was separated by decantation and concentrated to dryness. The obtained solid and 0.70 g of potassium tetrapyrazolyl boronate (abbreviation: Kbpz ₄ ) were mixed in a solvent of 30 ml of acetonitrile, and refluxed for 18 hours in a nitrogen atmosphere, whereby the organometallic complex Ir (fdpq) of the present invention was mixed. ) ₂ (bpz ₄ ) was obtained (red powder, yield 51%). A synthesis scheme (b-3) of Step 3 is shown below.

When the obtained red powder was analyzed by nuclear magnetic resonance spectroscopy ( ¹ H-NMR), the following results were obtained, and Ir (fdpq) ₂ (bpz), which is one of the organometallic complexes of the present invention. ₄ ).

¹ H-NMR. δ (CDCl ₃ ): 7.95 (d, 2H), 7.75 (brs, 4H), 7.55 (t, 2H), 7.23 (m, 10H), 7.09 (m, 4H) 6.82 (sd, 2H), 6.40 (td, 2H), 6.17 (m, 6H), 5.73 (s, 2H)

Further, when the decomposition temperature T _d of the obtained Ir (fdpq) ₂ (bpz ₄ ) was measured by a suggestive thermothermal gravimetric apparatus (Seiko Denshi Co., Ltd., TG / DTA), T _d = 334 ° C. It was found that good heat resistance was exhibited.

In addition, FIG. 7 shows an absorption spectrum and an emission spectrum of Ir (fdpq) ₂ (bpz ₄ ) in dichloromethane. The left vertical axis represents molar extinction coefficient (M ⁻¹ cm ⁻¹ ), and the right vertical axis represents luminescence intensity [arbitrary unit (au)]. Note that the emission spectrum is obtained when light having a wavelength of 468 nm extracted by splitting the light of the halogen lamp with a slit is used as excitation light. From FIG. 7, the organometallic complex Ir (fdpq) ₂ (bpz ₄ ) of the present invention has absorption peaks at 390 nm, 465 nm (sh), and 585 nm (sh). The emission spectrum was red emission having an emission peak at 634 nm.

In the obtained Ir (fdpq) ₂ (bpz ₄ ), a plurality of absorption peaks are observed on the long wavelength side. This is an absorption characteristic of an organometallic complex often found in ortho metal complexes and the like, and is assumed to correspond to a singlet MLCT transition, a triplet π-π ^* transition, a triplet MLCT (Metal to ligand charge transfer) transition, and the like. The In particular, the absorption peak on the longest wavelength side has a broad tail in the visible region, which is considered to be an absorption spectrum peculiar to the triplet MLCT transition. From these results, it was found that Ir (fdpq) ₂ (bpz ₄ ) is a compound capable of direct photoexcitation and intersystem crossing to the triplet excited state.

The obtained _{Ir (fdpq) 2 (bpz 4} ) injecting a gas containing oxygen to a dichloromethane solution containing, light emission when light is emitted oxygen with dissolved _{Ir (fdpq) 2 (bpz 4} ) The strength was examined. Also, argon was injected into a dichloromethane solution including the obtained _{Ir (fdpq) 2 (bpz 4} ) , examine the emission intensity when made to emit light _{Ir (fdpq) 2 (bpz 4} ) with dissolved argon It was. As a result, light emission derived from Ir (fdpq) ₂ (bpz ₄ ) was hardly observed in dissolved oxygen, whereas light emission was observed in a state where argon was dissolved, so that Ir (fdpq) ₂ ( It was confirmed that the luminescence observed from bpz ₄ ) was phosphorescence.

The obtained Ir (fdpq) ₂ (bpz ₄ ) can emit red phosphorescence that is closer to the NTSC red chromaticity coordinates and has excellent visibility.

Further, a light-emitting element manufactured using the obtained Ir (fdpq) ₂ (bpz ₄ ) will be described with reference to FIGS.

  First, an ITO film containing silicon oxide was formed over the substrate 700 by a sputtering method to form a first electrode 701.

  Next, the substrate 700 on which the first electrode 701 was formed was fixed to a substrate holder provided in the vacuum evaporation apparatus so that the surface on which the first electrode 701 was formed faced down. Then, DNTPD and molybdenum trioxide were formed over the first electrode 701 so as to have a thickness of 50 nm by co-evaporation, so that a hole injection layer 711 was formed. The mass ratio of DNTPD to molybdenum oxide was set to 4: 2 (= DNTPD: molybdenum oxide).

  Next, an NPB film was formed over the hole injection layer 711 so as to have a thickness of 10 nm using an evaporation method, whereby a hole transport layer 712 was formed.

On the hole-transport layer 712, CBP and Ir (fdpq) ₂ (bpz ₄ ) were formed to a thickness of 30 nm by co-evaporation, whereby a light-emitting layer 713 was formed. The mass ratio of CBP to Ir (fdpq) ₂ (bpz ₄ ) was 1: 0.08 (= CBP: Ir (fdpq) ₂ (bpz ₄ )). Thus, Ir (fdpq) ₂ (bpz ₄ ) is dispersed in the layer made of CBP.

  Over the light-emitting layer 713, BCP was formed to a thickness of 10 nm, whereby an electron-transport layer 714 was formed. The film formation was performed by a vapor deposition method.

Next, an electron injection layer 715 was formed on the electron transport layer 714 by co-evaporation of Alq ₃ and Li so as to have a thickness of 50 nm. The mass ratio between Alq ₃ and Li was 1: 0.01 (= Alq ₃ : Li).

  A second electrode 702 was formed over the electron injection layer 715 by depositing aluminum using an evaporation method.

  As described above, the hole injection layer 711, the hole transport layer 712, the light-emitting layer 713, the electron transport layer 714, and the electron injection layer 715 are stacked between the first electrode 701 and the second electrode 702. A light emitting element was manufactured.

Further, the obtained light-emitting element was sealed in a nitrogen atmosphere using a sealing material without being exposed to the air. A voltage was applied to the light-emitting element described in this example so that the potential of the first electrode 701 was higher than the potential of the second electrode 702, and the operating characteristics of the light-emitting element were examined. In addition, the measurement was performed in a state kept at room temperature (25 ° C.). The results are shown in FIG. 9A shows the result of examining the current density-luminance characteristics, FIG. 9B shows the result of examining the voltage-luminance characteristics, and FIG. 9C shows the results of examining the luminance-current efficiency characteristics. In FIG. 9A, the horizontal axis represents current density (mA / cm ² ), and the vertical axis represents luminance (cd / m ² ). In FIG. 9B, the horizontal axis represents voltage (V), and the vertical axis represents luminance (cd / m ² ). In FIG. 9C, the horizontal axis represents luminance (cd / m ² ), and the vertical axis represents current efficiency (cd / A).

From these results, it was found that when a voltage of 10.0 V was applied, light was emitted with a luminance of 1000 cd / m ² and the current efficiency at that time was 4.1 cd / A. The external quantum efficiency was 6.9%. Note that the external quantum efficiency is a ratio of the number of photons emitted outside the device to the number of electrons injected into the light emitting device. The calculation method is shown below.

The external quantum efficiency φ _ext can be expressed by the following formula (1), where Np is the number of photons per unit area and Ne is the number of electrons per unit area.

Np is L (luminance (cd / m ² )), I (λ) is normalized emission spectrum at each wavelength (normalized emission intensity at each wavelength), K (λ) is a standard relative luminous efficiency curve, and c is the speed of light. , H can be expressed by the following formula (2) where Planck constants are used.

Further, Ne can be expressed by the following mathematical formula (3), where J is current density (A / m ² ) and e is elementary charge amount (C).

The following formula (4) can be derived from the formulas (1) to (3).

  Therefore, the external quantum efficiency was calculated to be 6.9% from the current efficiency obtained from the above measurement and the emission spectrum shown in FIG.

  From FIG. 10, the peak wavelength of the emission spectrum was 638 nm, and the CIE chromaticity coordinates were (x, y) = (0.69, 0.31).

As described above, by using Ir (fdpq) ₂ (bpz ₄ ) as a light-emitting substance, a light-emitting element that emits red phosphorescence excellent in luminous sensitivity, which is closer to the NTSC standard red chromaticity coordinate, is obtained. I was able to. In addition, an element with high luminous efficiency could be obtained.

6A and 6B illustrate an element structure of a light-emitting element of the present invention. 6A and 6B illustrate an element structure of a light-emitting element of the present invention. 6A and 6B illustrate an element structure of a light-emitting element of the present invention. 6A and 6B illustrate an element structure of a light-emitting element of the present invention. The figure of the light-emitting device using the light emitting element of this invention Illustration of electronic device using light emitting element of the present invention The figure which shows the absorption spectrum and emission spectrum of the organometallic complex obtained by the synthesis example 1 of Example 1 4A and 4B illustrate an element structure of a light-emitting element manufactured in Example 1. FIG. 11 shows operating characteristics of the light-emitting element manufactured in Example 1 FIG. 11 shows an emission spectrum of the light-emitting element manufactured in Example 1. The figure of the light-emitting device using the light emitting element of this invention

Explanation of symbols

101 first electrode 102 second electrode 111 hole injection layer 112 hole transport layer 113 light emitting layer 114 electron transport layer 115 electron injection layer 201 first electrode 202 second electrode 211 electron injection layer 212 electron transport layer 213 First light emitting layer 214 Spacing layer 215 Second light emitting layer 216 Hole transport layer 217 Hole injection layer 301 First electrode 302 Second electrode 311 Electron injection layer 312 Electron transport layer 313 First light emitting layer 314 Positive Hole transport layer 315 First layer 316 Second layer 317 Electron transport layer 318 Second light emitting layer 319 Hole transport layer 320 Hole injection layer 401 First electrode 402 Second electrode 411 Hole injection layer 412 Positive Hole transport layer 413 Light emitting layer 414 Electron transport layer 415 Electron injection layer 500 Substrate 501 Source side driver circuit 502 Pixel portion 503 Gate side driver circuit 504 Sealing substrate 505 Lumpur material 506 space 507 wiring 508 FPC
511 Thin film transistor for switching 512 Thin film transistor for current control 513 First electrode 514 Insulator 515 Layer containing light emitting material 516 Second electrode 517 Light emitting element 521 n channel type thin film transistor 522 p channel type thin film transistor 600 Housing 601 Support base 602 Display portion 603 Speaker portion 604 Video input terminal 610 Main body 611 Case 612 Display portion 613 Keyboard 614 External connection port 615 Pointing mouse 620 Main body 621 Display portion 622 Case 623 External connection port 624 Remote control receiving portion 625 Image receiving portion 626 Battery 627 Audio input portion 628 Operation key 629 Eyepiece unit 630 Main body 631 Case 632 Display unit 633 Audio input unit 634 Audio output unit 635 Operation key 636 External connection port 637 Antenna 64 Main body 641 Display unit 642 Shutter 643 Operation key 644 Antenna 700 Substrate 701 First electrode 702 Second electrode 711 Hole injection layer 712 Hole transport layer 713 Light emitting layer 714 Electron transport layer 715 Electron injection layer 801 First substrate 802 First electrode 803 Partition layer 804 Layer 805 containing a luminescent substance Second electrode 806 Driver circuit 807 Driver circuit 808 Dotted line 809 Second substrate

Claims (11)

An organometallic complex represented by the general formula (1).
(Wherein R ^{1 to} R ³ represent any one of hydrogen, a halogen group, an acyl group, an alkyl group, an alkoxyl group, an aryl group, a cyano group, and a heterocyclic group, provided that at least one of R ^{1 to} R ³ is to display the electron-withdrawing substituent, the electron-withdrawing substituents are a halogen group, a haloalkyl group, or a cyano group. Further, M represents iridium, an n = 2.) An organometallic complex represented by the general formula (2).
(Wherein, R ¹ and R ² Represents an electron withdrawing group, the electron withdrawing substituent is a halogen group, a haloalkyl group, or a cyano group. Further, M represents iridium, n = 2.) An organometallic complex represented by the general formula (3).
(Wherein, R Represents an electron withdrawing group, the electron withdrawing substituent is a halogen group, a haloalkyl group, or a cyano group. Further, M represents iridium, is n = 2 .) In any one of Claims 1 thru | or 3,
The organometallic complex, wherein the electron-withdrawing substituent is a fluoro group or a trifluoromethyl group. An organometallic complex represented by Structural Formula (4).
An organometallic complex represented by Structural Formula (5).
A light-emitting element including a layer containing the organometallic complex according to any one of claims 1 to 6 between a pair of electrodes. Emitting element characterized by using the organometallic complex according as the light emitting material in any one of claims 1 to 6. Emitting device characterized by light-emitting elements are plural arrangement according to claim 7 or claim 8. A light emitting device using the light emitting element according to claim 7 or 8 as a pixel. Electronic apparatus, characterized by using the display unit the light-emitting device according to claim 9 or claim 10.