JP2007145834A - Stilbene derivative, light emitting element material, light emitting element, light emitting device and electronic appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new stilbene derivative having a large energy gap, a new light emitting element material having a large energy gap and especially suitable for a host material in a light emitting layer, and a new light emitting element material having a large energy gap and an electron transporting property. <P>SOLUTION: The present invention provides a stilbene derivative expressed by general formula (3) and a light emitting element material containing the stilbene derivative expressed by general formula (3) (n is an integer of 0-2; and m is an integer of 1-2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to novel materials. In particular, the present invention relates to a material suitable for use in a light-emitting element using an organic compound at least in part. In addition, the present invention relates to a light-emitting element, a light-emitting device, and an electronic device each including the material.

  Development of a light-emitting device using a light-emitting element that has a layer containing an organic compound between a pair of electrodes and emits light by passing a current between the electrodes is underway. Such a light-emitting device is advantageous for reduction in thickness and weight as compared with other display devices currently called thin display devices, and since it is self-luminous, it has good visibility and quick response. For this reason, development has been actively promoted as a next-generation display device, and some of the devices have been put into practical use.

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

  The layer containing the organic compound disposed between the electrodes may be a single layer structure composed of a single light emitting layer or a layered structure composed of layers each having a different function. In many cases, the laminated structure is used. As an example of such a function separation type laminated structure, a structure in which a hole injection layer, a hole transport layer, a light emitting layer, and an electron injection layer are laminated in this order from the electrode functioning as an anode is representative, Each layer is made of a material specializing in the function. Note that a layer having two or more of these functions such as a layer having both functions of a light emitting layer and an electron transport layer, and a layer having other functions such as a carrier blocking layer may be used.

  Among the functional layers, the light emitting layer is roughly classified into two according to the configuration. One is a structure in which a light emitting layer is formed by a film of a light emitting material alone. The other is a structure in which a light emitting layer is formed by dispersing a light emitting substance in a host material. In the latter configuration, the light emitting material can be selected without being influenced by the crystallinity and film forming characteristics of the light emitting material. In addition, it can be said that the structure is advantageous because concentration quenching hardly occurs.

  In the case of using such a light emitting layer formed by dispersing a light emitting substance in a host material, the energy gap of the host material needs to be larger than the energy gap of the light emitting substance. This prevents the excitation energy of the excited luminescent material from being transferred to the host material, causing changes in the light emission efficiency and luminescent color, as well as the transfer of excitation energy from the excited host material to the luminescent material smoothly. This is an important requirement for improving luminous efficiency.

  The color of light emitted from a luminescent material depends on the energy gap of the luminescent material. The light emitted from the light emitting material having a larger energy gap becomes light having a shorter emission wavelength. Therefore, the host material for the light-emitting substance that emits blue light needs to be a material having a very large energy gap. However, there are not many such materials yet. (See, for example, Patent Document 1) Further, a host material for a light-emitting substance that emits light in the purple or ultraviolet region is required to have a larger energy gap.

  By the way, when the light-emitting element is manufactured using the function-separated layered structure as described above, each functional layer is made of a material advantageous for each function. In order to obtain a high-performance light-emitting element, each functional layer must have excellent characteristics in all aspects. However, compared with the hole transport material constituting the hole transport layer, there are few reports on the electron transport material for constituting the electron transport layer, and the development of the material is delayed at present.

For example, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ) widely used as an electron transporting material has excellent electron transporting properties and reliability. However, as can be seen from the fact that the emission color is green, the energy gap is small. Therefore, it is difficult to use as an electron transporting layer in contact with a light emitting layer in a light emitting element that emits light having a wavelength of blue or shorter. This is because when the light emitting region in the light emitting layer is biased toward the electron transport layer, the excitation energy of the light emitting substance or the host material moves to the electron transport layer side with a small energy gap.

In order to avoid this problem, it is effective to use a host material as an electron transporting material and a light emitting region of the light emitting layer on the hole transport layer side. However, as mentioned above, there are few reports on electron transport materials, and there are very few materials that can be used as host materials in light emitting devices that emit light of blue or shorter wavelengths and have electron transport properties. Few.
JP 2005-132820 A

  Accordingly, an object of the present invention is to provide a novel stilbene derivative having a large energy gap. Another object of the present invention is to provide a novel material for a light-emitting element that has a large energy gap and is particularly suitable as a host material for a light-emitting layer. Another object of the present invention is to provide a novel light emitting device material having a large energy gap and electron transportability.

  Another object of the present invention is to provide a light-emitting element that includes any of the above-described stilbene derivatives and light-emitting element materials and has good color purity or light emission efficiency.

  It is another object of the present invention to provide a light-emitting device that includes any of the above-described stilbene derivatives and light-emitting element materials and has high display quality and low power consumption.

  It is another object of the present invention to provide an electronic device having a light-emitting device including any of the above-described stilbene derivatives and light-emitting element materials, with low power consumption and high display quality.

  The present invention is a stilbene derivative represented by the following general formula (1).

In the formula, R ¹ , R ² , R ³ , R ⁴ , and R ⁵ represent hydrogen or a substituent represented by the following structural formula (2), and R ¹ , R ² , R ³ , R ⁴ , R ⁵ At least one of them is a substituent represented by the following structural formula (2). Moreover, R < ⁶ >, R < ⁷ >, R < ⁸ >, R <^9> , R < ¹⁰ > represents hydrogen or a substituent represented by the following structural formula (2), and R < ⁶ >, R < ⁷ >, R < ⁸ >, R <^9> , R <^10>. At least one of them is a substituent represented by the following structural formula (2).

  The present invention is a stilbene derivative represented by the following general formula (3).

  In the formula, n represents an integer of 0 or more and 2 or less, and m represents an integer of 1 or more and 2 or less. Note that the case where n = 1 and m = 1 is a preferable configuration.

  The present invention is a stilbene derivative represented by the following structural formula (4).

  The present invention is a stilbene derivative represented by the following structural formula (5).

  The present invention is a light-emitting element material containing any one of the stilbene derivatives described above.

  The present invention is a light-emitting element including any of the stilbene derivatives described above.

  The present invention is a light-emitting element using the stilbene derivative according to any one of the above as a host material of a light-emitting layer.

  The present invention is an electronic device having the light-emitting element described above.

  The stilbene derivative of the present invention is a novel material having a large energy gap. The stilbene derivative of the present invention is a novel material having an electron transporting property and a large energy gap. The material for a light-emitting element of the present invention has a large energy gap, and is a novel light-emitting element material particularly suitable for a host material for a light-emitting layer. The light-emitting element material of the present invention is a novel light-emitting element material having a large energy gap and electron transportability.

  The light-emitting element of the present invention is a light-emitting element with favorable color purity or light emission efficiency.

  The light-emitting device of the present invention is a light-emitting device with high display quality or low power consumption.

  In addition, an electronic device of the present invention is an electronic device that includes a light emitting device and has low power consumption or high display quality.

  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)
In this embodiment mode, a stilbene derivative of the present invention will be described.

  The stilbene derivative of the present invention is represented by the following general formula (1).

In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ represent hydrogen or a substituent represented by the following structural formula (2), and among R ¹ , R ² , R ³ , R ⁴ and R ⁵ At least one is a substituent represented by the following structural formula (2). Moreover, R < ⁶ >, R < ⁷ >, R < ⁸ >, R <^9> , R < ¹⁰ > represents hydrogen or a substituent represented by the following structural formula (2), and R < ⁶ >, R < ⁷ >, R < ⁸ >, R <^9> , R <^10>. At least one of them is a substituent represented by the following structural formula (2).

  The substituent represented by the structural formula (2) may further have a substituent. Examples of the substituent include an alkyl group, a haloalkyl group, an alkoxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, Examples thereof include a halogen group and an aryl group. Specifically, the alkyl group is a methyl or ethyl group, the haloalkyl group is a trifluoromethyl group, the alkoxy group is a methoxy group, the acyl group is an acetyl group, the alkoxycarbonyl group is a methoxycarbonyl group, and the acyloxy group is acetoxy. Examples of the group and halogen group include a fluoro group, and examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group.

  The stilbene derivative of the present invention is represented by the following general formula (3).

  In the formula, n represents an integer of 0 to 2, and m represents an integer of 1 to 2. In this case, a case where n = 1 and m = 1 is a preferable configuration.

  The stilbene derivative of the present invention is represented by the following structural formula (4).

  The stilbene derivative of the present invention is represented by the following structural formula (5).

  The stilbene derivative of the present invention having the above structure is a material having a large energy gap. By using the stilbene derivative of the present invention as a host material of a light emitting layer in a layer containing an organic compound of a light emitting element, even if a substance that emits blue light is used as the light emitting substance, the excitation energy from the light emitting substance to the host material is reduced. It is possible to manufacture a light-emitting element with high luminous efficiency and color purity without movement.

  The stilbene derivative of the present invention having the above structure is a material having an electron transporting property. Therefore, by using the stilbene derivative of the present invention as the host material of the light-emitting layer in the layer containing the organic compound of the light-emitting element, the light-emitting region does not have to be biased toward the electron transport layer side where the selection range of the material is small. . Accordingly, it becomes easy to design a light emitting element with high luminous efficiency and color purity, and a light emitting element with high luminous efficiency and high color purity can be manufactured.

  The stilbene derivative of the present invention having the above structure is a material having a large energy gap and an electron transporting property. By using the stilbene derivative of the present invention as a host material of a light emitting layer in a layer containing an organic compound of a light emitting element, even if a substance that emits blue light is used as the light emitting substance, the excitation energy from the light emitting substance to the host material is reduced. Since no movement occurs and the light-emitting element can be easily designed, a light-emitting element with high emission efficiency and high color purity can be manufactured.

  Note that the stilbene derivative of the present invention having the above structure can be applied not only to a light-emitting element that emits blue light but also to a light-emitting element using a material that emits light having a longer wavelength than blue, such as red or green, as a light-emitting substance. . However, it is preferable that there is an overlap between the emission wavelength range of the stilbene derivative of the present invention and the absorption wavelength range of the luminescent material for smooth transfer of excitation energy from the stilbene derivative of the present invention to the luminescent material. .

  In addition, the stilbene derivative of the present invention is a light-emitting element that emits light in a wavelength range shorter than blue (purple to ultraviolet light) in a range where the energy gap of the light-emitting substance used is smaller than the energy gap of the stilbene derivative described in Embodiment 1. It can also be applied as a host material. Since the stilbene derivative of the present invention has a very large energy gap, it can be suitably used as a host material for a light-emitting substance that emits light in the wavelength range of purple to ultraviolet light.

(Embodiment 2)
In this embodiment, a light-emitting element using the stilbene derivative described in Embodiment 1 will be described.

  The structure of the light-emitting element in the present invention has a layer containing an organic compound between a pair of electrodes. Note that there is no particular limitation on the element structure, and the structure can be appropriately selected according to the purpose.

  FIG. 1 schematically shows an example of an element structure of a light emitting element in the present invention. 1 has a structure in which a layer 102 containing an organic compound is provided between a first electrode 101 and a second electrode 103 over an insulator 100. The layer 102 containing an organic compound contains the stilbene derivative described in Embodiment 1. Note that the anode in the present invention refers to an electrode that injects holes into a layer containing a light-emitting substance. Further, the cathode in the present invention refers to an electrode that injects electrons into a layer containing a light emitting substance. One of the first electrode 101 and the second electrode 103 is an anode, and the other is a cathode.

  As the anode, it is preferable to use a metal, an alloy, a conductive compound, a mixture thereof, or the like having a high work function (specifically, 4.0 eV or more). Specifically, indium tin oxide (hereinafter referred to as ITO), indium tin oxide containing silicon, indium oxide containing zinc oxide (ZnO), or the like can be given. These conductive metal oxide films are usually formed by sputtering, but may be formed by applying a sol-gel method or the like. In addition, 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, titanium nitride: TiN) can also be used.

  On the other hand, it is preferable to use a metal, an alloy, a conductive compound, a mixture thereof, or the like having a low work function (specifically, 3.8 eV or less) as the cathode. Specifically, metals belonging to Group 1 or Group 2 of the Periodic Table of Elements, that is, alkali metals such as lithium (Li) and cesium (Cs), magnesium (Mg), calcium (Ca), strontium (Sr), etc. Examples include alkaline earth metals, alloys containing these (MgAg, AlLi, etc.), rare earth metals such as europium (Er), ytterbium (Yb), and alloys containing these. However, by using an electron injection layer having a high electron injection property, the cathode can be formed of a material having a high work function, that is, a material normally used for an anode. For example, the cathode can be formed of a metal / conductive inorganic compound such as Al, Ag, or ITO.

  For the layer 102 containing an organic compound, either a low molecular material or a high molecular material can be used. Note that the material forming the layer 102 containing an organic compound includes not only a material made of only an organic compound material but also a structure containing an inorganic compound in part. The layer containing an organic compound is usually a functional layer having each function such as a hole injection layer, a hole transport layer, a hole blocking layer (hole blocking layer), a light emitting layer, an electron transport layer, an electron injection layer, and the like. Although it is configured in combination as appropriate, a layer having two or more functions of each layer may be included. In this embodiment mode, a layered structure of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is used as the layer containing an organic compound. Note that in this embodiment mode, the light-emitting layer is formed by dispersing a light-emitting substance in a host material formed using the stilbene derivative described in Embodiment Mode 1. For this reason, concentration quenching can be prevented as compared with the case where the light emitting layer is formed of a film of a light emitting material alone.

  In addition, the layer 102 containing an organic compound can be formed by either a wet method or a dry method such as an evaporation method, an inkjet method, a spin coating method, or a dip coating method.

  The stilbene derivative described in Embodiment 1 is a material having a large energy gap. The light-emitting element of the present invention includes the stilbene derivative described in Embodiment 1 as a host material of the light-emitting layer in the layer 102 containing an organic compound. Therefore, even when a substance that emits blue light is used as the light-emitting substance, transfer of excitation energy from the light-emitting substance to the host material does not occur. Thus, the light emitting element of the present invention can be a light emitting element with high luminous efficiency and color purity.

  In addition, the stilbene derivative described in Embodiment 1 has an electron transporting property. The light-emitting element of the present invention includes the stilbene derivative described in Embodiment 1 as a host material of the light-emitting layer in the layer 102 containing an organic compound. Therefore, the light emitting region does not have to be biased toward the electron transport layer side where the material selection range is small. Accordingly, it becomes easy to design a light emitting element with high luminous efficiency and color purity, and the light emitting element of the present invention can be made into a light emitting element with high luminous efficiency and high color purity.

  The stilbene derivative described in Embodiment 1 is a material having a large energy gap and an electron transporting property. The light-emitting element of the present invention includes the stilbene derivative described in Embodiment 1 as a host material of the light-emitting layer in the layer 102 containing an organic compound. Therefore, even when a substance that emits blue light is used as the light-emitting substance, excitation energy does not move from the light-emitting substance to the host material, and the light-emitting element can be easily designed. Accordingly, the light-emitting element of the present invention can be a light-emitting element with high emission efficiency and high color purity.

  Note that the light-emitting element of the present invention can be applied not only to a light-emitting element that emits blue light but also to a light-emitting element that uses a material that emits light having a longer wavelength than blue, such as red or green, as a light-emitting substance. However, it is preferable that there is an overlap between the emission wavelength range of the host material and the absorption wavelength range of the luminescent material so that the excitation energy can be smoothly transferred from the host material to the luminescent material.

  The light-emitting element of the present invention emits light in a wavelength region shorter than blue (purple to ultraviolet light) in a range where the energy gap of a light-emitting substance to be used is smaller than the energy gap of the stilbene derivative described in Embodiment 1. It is also possible to apply. Since the stilbene derivative described in Embodiment 1 has a very large energy gap, the stilbene derivative can be suitably used as a host material for a light-emitting substance that emits light in a wavelength range of violet to ultraviolet light.

The hole injection layer can be formed using a metal oxide such as vanadium oxide, molybdenum oxide, ruthenium oxide, or aluminum oxide, or a mixture in which an appropriate organic compound is mixed. Alternatively, a porphyrin-based compound is effective as long as it is an organic compound, and phthalocyanine (abbreviation: H ₂ Pc), copper phthalocyanine (abbreviation: CuPc), or the like can be used. In addition, there is a material obtained by chemically doping a conductive polymer compound, and polyethylenedioxythiophene (abbreviation: PEDOT) doped with polystyrene sulfonic acid (abbreviation: PSS), polyaniline (abbreviation: PAni), or the like is used. it can. The hole injection layer is formed in contact with the anode. By using the hole injection layer, the carrier injection barrier is reduced, and carriers are efficiently injected into the light-emitting element. As a result, the driving voltage can be reduced. it can.

The hole-transport layer includes N, N′-bis (spiro-9,9′-bifluoren-2-yl) -N, N′-diphenylbenzidine (abbreviation: BSPB), 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''- tris (N- carbazolyl) triphenylamine (abbreviation: TCTA), phthalocyanine _{(abbreviation:} H 2 Pc), copper phthalocyanine (abbreviation: CuPc), An appropriate material such as vanadyl phthalocyanine (abbreviation: VOPc) can be used. Further, the hole transport layer may be a layer having a multilayer structure in which two or more layers made of the above-described substances are combined.

The light-emitting layer is formed by dispersing a light-emitting substance in a host material formed using the stilbene derivative described in Embodiment 1. As the light-emitting substance, a substance that has favorable emission efficiency and can emit light with a desired emission wavelength may be used. For example, to obtain red light emission, 4-dicyanomethylene-2-isopropyl-6- [2- (1,1,7,7-tetramethyljulolidin-9-yl) ethenyl] -4H-pyran ( Abbreviation: DCJTI), 4-dicyanomethylene-2-methyl-6- [2- (1,1,7,7-tetramethyljulolidin-9-yl) ethenyl] -4H-pyran (abbreviation: DCJT), 4 -Dicyanomethylene-2-tert-butyl-6- [2- (1,1,7,7-tetramethyljulolidin-9-yl) ethenyl] -4H-pyran (abbreviation: DCJTB), periflanthene, 1,4 -Bis [2- (10-methoxy-1,1,7,7-tetramethyljulolidin-9-yl) ethenyl] -2,5-dicyanobenzene, etc., emission spectrum from 600 nm to 680 nm It can be used and a substance which exhibits emission with a peak. When green light emission is desired, N, N′-dimethylquinacridone (abbreviation: DMQd), coumarin 6, coumarin 545T, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), etc., emits light from 500 nm to 550 nm. A substance exhibiting light emission having a spectral peak can be used. When blue light emission is desired, 2,5,8,11-tetra (tert-butyl) perylene (abbreviation: TBP), 9,10-di (2-naphthyl) -tert-butylanthracene (abbreviation) : T-BuDNA), 9,9′-bianthryl, 9,10-diphenylanthracene (abbreviation: DPA), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), bis (2-methyl-8- Quinolinolato) -4-phenylphenolato-gallium (abbreviation: BGaq), bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq), and the like. A substance exhibiting light emission can be used. When light emission in the wavelength range of purple to ultraviolet light is desired, TPD, m-MTDATA, 4,4′-bis [N- (biphenyl-4-yl) -N-phenylamino] biphenyl (abbreviation: BBPB) 2,2 ′, 7,7′-tetrakis (N-diphenylamino) -spiro-9,9′-bifluorene (abbreviation: spiro-TAD), 1,3,5-tris [N, N-bis (2 -Methylphenyl) amino] benzene (o-MTDAB) and the like can be used. As described above, in addition to a substance that emits fluorescence, 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 (FIr (pic)), tris (2-phenylpyridinato-N, C ^{2 ′} ) iridium (abbreviation) A substance that emits phosphorescence such as Ir (ppy) ₃ ) can also be used as the light-emitting material. A light-emitting layer can be formed by adding a light-emitting substance in the host material at a ratio of 0.001 to 50 wt%, preferably 0.03 to 20 wt%.

When using an electron transport layer, it is installed between the light emitting layer and the electron injection layer. Suitable materials 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-hydroxy-biphenylyl) -aluminum (abbreviation: BAlq), bis [2- (2′-hydroxyphenyl) -benzoxazolate] zinc And metal complexes such as (abbreviation: Zn (BOX) ₂ ) and bis [2- (2′-hydroxyphenyl) -benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ). Alternatively, hydrocarbon compounds such as 9,10-diphenylanthracene and 4,4′-bis (2,2-diphenylethenyl) biphenyl are also suitable. Alternatively, triazole derivatives such as 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2,4-triazole, phenanthroline derivatives such as bathophenanthroline and bathocuproin May be used.

The electron injecting material for forming the electron injecting layer is not particularly limited. Specifically, alkali metal salts such as calcium fluoride, lithium fluoride, lithium oxide, and lithium chloride, alkaline earth metal salts, and the like are preferable. Alternatively, a layer in which a donor compound such as lithium is added to a so-called electron transporting material such as tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ) or bathocuproin (abbreviation: BCP) can also be used. The electron injecting layer is formed in contact with the cathode. By using the electron injecting layer, the carrier injection barrier is reduced and carriers are efficiently injected into the light emitting element. As a result, the driving voltage can be reduced.

  In the embodiment of the present invention, the structure of the light emitting element that can emit light only from the light emitting layer is shown. However, not only the light emitting layer but also other layers such as an electron transport layer and a hole transport layer can emit light. You can design. For example, by adding a dopant for light emission to the electron transport layer or hole transport layer, light emission from not only the light emitting layer but also the transport layer can be obtained. If the light emitting colors of the light emitting materials used for the light emitting layer and the transport layer are different, a spectrum in which the light emission overlaps is obtained. If the emission colors are complementary to each other, white light emission can be obtained.

  Note that the light-emitting element of this embodiment has various variations by changing types of the first electrode 101 and the second electrode 103. By making the first electrode 101 light transmissive, light is emitted from the first electrode 101 side. In addition, the first electrode 101 is made light-shielding (particularly reflective), and the second electrode 103 is made light-transmissive so that light is emitted from the second electrode 103 side. Furthermore, by making both the first electrode 101 and the second electrode 103 light transmissive, it is possible to emit light to both the first electrode side and the second electrode side.

(Embodiment 3)
In this embodiment mode, a light-emitting device of the present invention will be described with reference to FIGS. Note that although an example in which an active matrix light-emitting device is formed is described in this embodiment mode, the present invention can also be applied to a passive light-emitting device.

  First, after the first base insulating layer 51a and the second base insulating layer 51b are formed over the substrate 50, a semiconductor layer is further formed over the second base insulating layer 51b. (Fig. 2 (A))

  As a material of the substrate 50, glass, quartz, plastic (polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyacrylate, polyethersulfone, or the like) can be used. These substrates may be used after being polished by CMP or the like, if necessary. In this embodiment, a glass substrate is used.

  The first base insulating layer 51a and the second base insulating layer 51b prevent an element such as an alkali metal or an alkaline earth metal in the substrate 50 that adversely affects the characteristics of the semiconductor film from diffusing into the semiconductor layer. Provided for this purpose. As a material, silicon oxide, silicon nitride, silicon oxide containing nitrogen, silicon nitride containing oxygen, or the like can be used. In this embodiment mode, the first base insulating layer 51a is formed using silicon nitride, and the second base insulating layer 51b is formed using silicon oxide. In this embodiment mode, the base insulating layer is formed of the first base insulating layer 51a and the second base insulating layer 51b. However, the base insulating layer may be formed of a single layer or a multilayer of two or more layers. It doesn't matter. Further, if the diffusion of impurities from the substrate does not become a problem, it is not necessary to provide a base insulating layer.

  The semiconductor layer formed subsequently is obtained by laser crystallization of an amorphous silicon film in this embodiment mode. An amorphous silicon film is formed to a thickness of 25 to 100 nm (preferably 30 to 60 nm) over the second base insulating layer 51b. As a manufacturing method, for example, a sputtering method, a low pressure CVD method, a plasma CVD method, or the like can be used. After that, heat treatment is performed at 500 ° C. for 1 hour to dehydrogenate.

  Subsequently, the amorphous silicon film is crystallized using a laser irradiation apparatus to form a crystalline silicon film. In the laser crystallization of the present embodiment, an excimer laser is used, and a laser beam oscillated is shaped into a linear beam spot using an optical system and irradiated to an amorphous silicon film to form a crystalline silicon film. Used as a semiconductor layer. Note that the amorphous silicon film may be used as a semiconductor layer.

  Other crystallization methods for the amorphous silicon film include a method for crystallization only by heat treatment and a method for heat treatment using a catalyst element that promotes crystallization. Examples of elements that promote crystallization include nickel, iron, palladium, tin, lead, cobalt, platinum, copper, and gold. By using such an element, crystallization is performed at a low temperature and in a short time as compared with the case where crystallization is performed only by heat treatment, so that damage to the glass substrate and the like is small. When crystallization is performed only by heat treatment, the substrate 50 may be a quartz substrate resistant to heat.

  Subsequently, in order to control the threshold voltage of the semiconductor layer as necessary, a small amount of impurities are added, so-called channel doping. In order to obtain a required threshold voltage, an N-type or P-type impurity (phosphorus, boron, etc.) is added by an ion doping method or the like.

  After that, as shown in FIG. 2A, the semiconductor layer is processed into a predetermined shape, and an island-shaped semiconductor layer 52 is obtained. In processing the island-shaped semiconductor layer 52, first, a photoresist is applied to the semiconductor layer, and a predetermined mask shape is exposed. After exposure, baking is performed to form a resist mask over the semiconductor layer. Thereafter, the island-shaped semiconductor layer 52 is processed by etching using this mask.

  Subsequently, a gate insulating layer 53 is formed so as to cover the semiconductor layer 52. The gate insulating layer 53 is formed of an insulating layer containing silicon with a film thickness of 40 to 150 nm using a plasma CVD method or a sputtering method. In this embodiment mode, silicon oxide is used.

  Next, the gate electrode 54 is formed over the gate insulating layer 53. The gate electrode 54 may be formed of an element selected from tantalum, tungsten, titanium, molybdenum, aluminum, copper, chromium, and niobium, or an alloy material or a compound material containing the element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used.

  Further, although the gate electrode 54 is formed as a single layer in this embodiment mode, a stacked structure of two or more layers such as tungsten in the lower layer and molybdenum in the upper layer may be used. Even in the case where the gate electrode is formed as a stacked structure, the materials described in the preceding stage may be used. Moreover, the combination may be selected as appropriate. The gate electrode 54 is processed by forming a mask using a photoresist and etching using the mask.

  Subsequently, a high concentration impurity is added to the semiconductor layer 52 using the gate electrode 54 as a mask. Thus, the thin film transistor 70 including the semiconductor layer 52, the gate insulating layer 53, and the gate electrode 54 is formed.

  Note that there is no particular limitation on the manufacturing process of the thin film transistor, and it may be changed as appropriate so that a transistor with a desired structure can be manufactured.

  In this embodiment mode, a top-gate thin film transistor using a crystalline silicon film crystallized by laser crystallization is used; however, a bottom-gate thin film transistor using an amorphous semiconductor film is used for a pixel portion. It is also possible. As the amorphous semiconductor, not only silicon but also silicon germanium can be used. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.

  Subsequently, an insulating film (hydrogenated film) 59 is formed of silicon nitride so as to cover the gate electrode 54 and the gate insulating layer 53. After the insulating film (hydrogenated film) 59 is formed, heating is performed at 480 ° C. for about 1 hour to activate the impurity element and hydrogenate the semiconductor layer 52.

  Subsequently, a first interlayer insulating layer 60 covering the insulating film (hydrogenated film) 59 is formed. As a material for forming the first interlayer insulating layer 60, silicon oxide, acrylic, polyimide, siloxane, a low-k material, or the like may be used. In this embodiment mode, the silicon oxide film is formed as the first interlayer insulating layer. (Fig. 2 (B))

  Next, a contact hole reaching the semiconductor layer 52 is opened. The contact hole can be formed by performing etching using a resist mask until the semiconductor layer 52 is exposed. The contact hole can be formed by either wet etching or dry etching. Note that etching may be performed once depending on conditions, or etching may be performed in a plurality of times. In addition, when etching is performed a plurality of times, both wet etching and dry etching may be used. (Fig. 2 (C))

  Then, a conductive layer covering the contact hole and the first interlayer insulating layer 60 is formed. The conductive layer is processed into a desired shape, and the connection portion 61a, the wiring 61b, and the like are formed. The wiring may be a single layer of aluminum, copper, an alloy of aluminum, carbon, and nickel, an alloy of aluminum, carbon, and molybdenum. Alternatively, a laminated structure of molybdenum, aluminum, and molybdenum, or a structure of titanium, aluminum, titanium, titanium, titanium nitride, aluminum, or titanium from the substrate side may be used. (Fig. 2 (D))

  Thereafter, a second interlayer insulating layer 63 is formed so as to cover the connection portion 61a, the wiring 61b, and the first interlayer insulating layer 60. As a material for the second interlayer insulating layer 63, a coating film of acrylic, polyimide, siloxane or the like having self-flatness can be suitably used. In this embodiment mode, siloxane is used as the second interlayer insulating layer 63. (Figure 2 (E))

  Subsequently, an insulating layer may be formed of silicon nitride or the like on the second interlayer insulating layer 63. The insulating layer is formed in order to prevent the second interlayer insulating layer 63 from being etched more than necessary in the subsequent etching of the pixel electrode. Therefore, when the ratio of the etching rate between the pixel electrode and the second interlayer insulating layer is large, it may not be provided. Subsequently, a contact hole that penetrates through the second interlayer insulating layer 63 and reaches the connection portion 61a is formed.

  Then, a conductive layer is formed so as to cover the contact hole and the second interlayer insulating layer 63 (or insulating layer). Thereafter, the conductive layer is processed to form the first electrode 64 of the thin film light emitting element. Here, the first electrode 64 is in electrical contact with the connecting portion 61a. (Fig. 3 (A))

  As the material of the first electrode 64, aluminum (Al), silver (Ag), gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), strontium (Sr), titanium (Ti), etc. Metals having conductivity, alloys of aluminum and silicon (Al-Si), alloys of aluminum and titanium (Al-Ti), alloys of aluminum, silicon and copper (Al-Si-Cu), etc. Or a nitride such as titanium nitride (TiN), indium tin oxide (ITO), ITO containing silicon oxide (hereinafter IT) SO), and a conductive film such as a metal compound such as IZO (indium zinc oxide) in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide.

  In addition, an electrode for extracting light may be formed of a conductive film having transparency, and an extremely thin film of metal such as Al or Ag is used in addition to a metal compound such as ITO, ITSO, or IZO. In the case where light emission is extracted from the second electrode, a material with high reflectivity (Al, Ag, or the like) can be used for the first electrode. In this embodiment mode, ITSO is used as the first electrode 64 (FIG. 3A).

  Next, an insulating layer made of an organic material or an inorganic material is formed so as to cover the second interlayer insulating layer 63 (or the insulating layer) and the first electrode 64. Subsequently, the insulating layer is processed so that a part of the first electrode 64 is exposed, and a partition wall 65 is formed. As the material of the partition wall 65, a photosensitive organic material (acrylic, polyimide, or the like) is preferably used, but it may be formed of an organic material or an inorganic material that does not have photosensitivity. Further, a black pigment or dye such as titanium black or carbon nitride may be dispersed in the material of the partition wall 65 by using a dispersing material or the like, and the partition wall 65 may be made black to be used like a black matrix. It is desirable that the end face of the partition wall 65 facing the first electrode has a curvature and has a tapered shape in which the curvature continuously changes (FIG. 3B).

  Next, a layer 66 containing an organic compound is formed, and then a second electrode 67 covering the layer 66 containing an organic compound is formed. Accordingly, the light-emitting element 93 in which the layer 66 containing an organic compound is sandwiched between the first electrode 64 and the second electrode 67 can be manufactured, and the first electrode 64 is higher than the second electrode 67. Light emission can be obtained by applying a voltage. As an electrode material used for forming the second electrode 67, the same material as the material of the first electrode 64 can be used. In this embodiment mode, aluminum is used for the second electrode 67. (Figure 3 (C))

  For the layer 66 containing an organic compound, either a low molecular material or a high molecular material can be used. In addition, the layer 66 including an organic compound in the light-emitting device of this embodiment includes the stilbene derivative described in Embodiment 1. Note that the material for forming the layer 66 including an organic compound includes not only a material composed of only an organic compound material but also a material partially including an inorganic compound. In addition, as a method for forming the layer 66 containing an organic compound, any of wet and dry methods such as an evaporation method, an inkjet method, a spin coating method, and a dip coating method can be used. The layer 66 containing an organic compound is usually a functional layer having each function such as a hole injection layer, a hole transport layer, a hole blocking layer (hole blocking layer), a light emitting layer, an electron transport layer, an electron injection layer, and the like. Are appropriately combined, but each layer may include a layer having two or more functions at the same time. In this embodiment mode, a layered structure of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is used as the layer containing an organic compound. In the light-emitting device in this embodiment, the stilbene derivative described in Embodiment 1 is used as the light-emitting layer. There is no particular limitation on the other functional layers in the layer 66 containing an organic compound, and those materials have been described in Embodiment 2 and thus repeated description is omitted.

Thereafter, a silicon oxide film containing nitrogen is formed as a passivation film by a plasma CVD method. In the case of using a silicon oxide film containing nitrogen, a silicon oxynitride film manufactured from SiH ₄ , N ₂ O, NH ₃ by a plasma CVD method, or a silicon oxynitride film manufactured from SiH ₄ , N ₂ O, Alternatively, a silicon oxynitride film formed from a gas obtained by diluting SiH ₄ and N ₂ O with Ar may be formed.

Further, a silicon oxynitride silicon film formed from SiH ₄ , N ₂ O, and H ₂ may be applied as the passivation film. Of course, the passivation film is not limited to a single layer structure, and another insulating layer containing silicon may be used as a single layer structure or a laminated structure. Further, a multilayer film of carbon nitride film and silicon nitride film, a multilayer film of styrene polymer, a silicon nitride film, or a diamond-like carbon film may be formed instead of the silicon oxide film containing nitrogen.

  Subsequently, the display portion is sealed in order to protect the light emitting element 93 from a substance that promotes deterioration such as water. In the case where the counter substrate is used for sealing, bonding is performed with an insulating sealing material so that the external connection portion is exposed. A space between the counter substrate and the element substrate may be filled with an inert gas such as dry nitrogen, or a sealing material may be applied to the entire surface of the pixel portion to bond the counter substrate. It is preferable to use an ultraviolet curable resin or the like for the sealing material. The sealing material may contain a desiccant or particles for keeping the gap between the substrates constant. Subsequently, a flexible wiring substrate is attached to the external connection portion, whereby the light emitting device is completed.

  One example of the structure of the light-emitting device manufactured as described above will be described with reference to FIG. In addition, even if the shapes are different, parts showing similar functions are denoted by the same reference numerals, and explanations thereof are omitted. In this embodiment mode, the thin film transistor 70 having an LDD structure is connected to the light emitting element 93 through the connection portion 61a.

  FIG. 4A illustrates a structure in which the first electrode 64 is formed using a light-transmitting conductive film, and light emitted from the layer 66 containing an organic compound is extracted to the substrate 50 side. Reference numeral 94 denotes a counter substrate, which is fixed to the substrate 50 by using a sealing material or the like after the light emitting element 93 is formed. Filling the counter substrate 94 with the light-transmitting resin 88 or the like between the elements and sealing them can prevent the light-emitting element 93 from being deteriorated by moisture. Further, it is desirable that the resin 88 has a hygroscopic property. Further, if a desiccant 89 having high translucency is dispersed in the resin 88, the influence of moisture can be further suppressed, which is a more desirable form.

  FIG. 4B illustrates a structure in which both the first electrode 64 and the second electrode 67 are formed using a light-transmitting conductive film, and light can be extracted to both the substrate 50 and the counter substrate 94. It has become. Further, in this configuration, by providing the polarizing plate 90 outside the substrate 50 and the counter substrate 94, it is possible to prevent the screen from being seen through, and visibility is improved. A protective film 91 may be provided outside the polarizing plate 90.

  Although a top gate thin film transistor is used in this embodiment mode, a light emitting device may be formed using a thin film transistor of another shape such as a bottom gate.

  Note that either an analog video signal or a digital video signal may be used for the light-emitting device of the present invention having a display function. When a digital video signal is used, there are a video signal using voltage and a video signal using current. When the light emitting element emits light, a video signal input to the pixel includes a constant voltage signal and a constant current signal. A video signal having a constant voltage includes a constant voltage applied to the light emitting element and a constant current flowing through the light emitting element. In addition, a video signal having a constant current includes a constant voltage applied to the light emitting element and a constant current flowing in the light emitting element. A constant voltage drive is applied to the light emitting element. In addition, constant current driving is performed when the current flowing through the light emitting element is constant. In constant current driving, a constant current flows regardless of the resistance change of the light emitting element. Any of the above driving methods may be used for the light emitting device and the driving method thereof of the present invention.

  As described above, the light-emitting device of the present invention including the stilbene derivative described in Embodiment Mode 1 in the layer 66 containing an organic compound has a large energy gap, and thus the excitation energy from the light-emitting substance to the host material is large. No movement occurs. Accordingly, the light emitting device of the present invention can be a light emitting device with low power consumption and improved display quality. In the light-emitting device of the present invention, since the stilbene derivative has electron transport properties, it is easy to design a light-emitting element with high light emission efficiency and high color purity, and the light-emitting device of the present invention has low power consumption and improved display quality. The light emitting device can be obtained. In the light-emitting device of the present invention, since the stilbene derivative is a material having an electron transporting property and a large energy gap, excitation energy does not move from the light-emitting substance to the host material, and the light-emitting element is designed. Cheap. Accordingly, the light emitting device of the present invention can be a light emitting device with low power consumption and improved display quality.

  This embodiment mode can be used in combination with an appropriate structure of Embodiment Mode 1 or Embodiment Mode 2.

(Embodiment 4)
In this embodiment mode, the appearance of a panel which is a light-emitting device of the present invention will be described with reference to FIG. FIG. 5A is a top view of a panel in which a transistor formed over a substrate 4001 and a light-emitting element 4011 are sealed with a sealant 4005 formed between a counter substrate 4006 and FIG. FIG. 5B corresponds to the cross-sectional view of FIG. Further, the structure of the light emitting element mounted on this panel is the structure as shown in Embodiment Mode 2.

  A sealant 4005 is provided so as to surround the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004 which are provided over the substrate 4001. A counter substrate 4006 is provided over the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004. Therefore, the pixel portion 4002, the signal line driver circuit 4003, the driver circuit 4020, and the scan line driver circuit 4004 are sealed together with the filler 4007 by the substrate 4001, the sealant 4005, and the counter substrate 4006.

  In addition, the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004 provided over the substrate 4001 include a plurality of thin film transistors. FIG. 5B illustrates a thin film transistor 4008 included in the signal line driver circuit 4003 and a thin film transistor 4010 included in the pixel portion 4002.

  The light emitting element 4011 is electrically connected to the thin film transistor 4010.

  The lead wiring 4014 corresponds to a wiring for supplying a signal or a power supply voltage to the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004. The lead wiring 4014 is connected to the connection terminal 4016 through the lead wiring 4015. The connection terminal 4016 is electrically connected to a terminal included in the flexible printed wiring board 4018 through an anisotropic conductive film 4019.

  Note that as the filler 4007, in addition to an inert gas such as nitrogen or argon, an ultraviolet curable resin or a thermosetting resin can be used, and polyvinyl chloride, acrylic, polyimide, epoxy resin, silicon resin, polyvinyl butyral, Alternatively, ethylene vinylene acetate can be used.

  Note that the light-emitting device of the present invention includes in its category a panel in which a pixel portion having a light-emitting element is formed and a module in which an IC is mounted on the panel.

  The signal line driver circuit 4003, the scanning line driver circuit 4004, and the IC, which are signal processing circuits as described above, are light emitting element control circuits, and a light emitting device and an electronic device equipped with these control circuits are controlled by the control circuit. Various images can be displayed on the panel by turning on / off or controlling brightness. A signal processing circuit formed on an external circuit board connected via the flexible printed wiring board 4018 is also a control circuit.

  The light-emitting device of the present invention as described above includes the light-emitting element described in Embodiment 2 in which the stilbene derivative described in Embodiment 1 is included in a layer including an organic compound as a light-emitting element included in the pixel portion. Therefore, the light-emitting device has improved power consumption and display quality in the pixel portion. In addition, the light-emitting device of the present invention includes the light-emitting element described in Embodiment 2 that includes the stilbene derivative described in Embodiment 1 in a layer including an organic compound as a light-emitting element that forms a pixel portion. This light-emitting device has improved power consumption and display quality.

  This embodiment can be combined with any of the structures of Embodiments 1 to 3 as appropriate.

(Embodiment 5)
In this embodiment, pixel circuits and protection circuits included in the panel and module described in Embodiment 4 and operations thereof will be described. Note that the cross-sectional views shown in FIGS. 2 and 3 are schematic cross-sectional views of the driving TFT 1403 and the light emitting element 1405.

  6A has a structure in which signal lines 1410 and power supply lines 1411 and 1412 are arranged in the column direction, and scanning lines 1414 are arranged in the row direction. The pixel further includes a switching TFT 1401, a driving TFT 1403, a current control TFT 1404, a capacitor element 1402, and a light emitting element 1405.

  The structure of the pixel illustrated in FIG. 6C is the same as that of the pixel illustrated in FIG. 6A except that the gate electrode of the driving TFT 1403 is connected to the power supply line 1412 arranged in the row direction. It is. That is, both pixels shown in FIGS. 6A and 6C show the same equivalent circuit diagram. However, in the case where the power supply line 1412 is arranged in the row direction (FIG. 6A) and the case where the power supply line 1412 is arranged in the column direction (FIG. 6C), each power supply line has a different layer. It is formed of a conductive film. Here, attention is paid to the wiring to which the gate electrode of the driving TFT 1403 is connected, and FIGS. 6A and 6C are separately illustrated in order to indicate that the layers for manufacturing these are different.

  As a feature of the pixel shown in FIGS. 6A and 6C, a driving TFT 1403 and a current control TFT 1404 are connected in series in the pixel. The channel length L (1403) and channel width W (1403) of the driving TFT 1403, the channel length L (1404) and channel width W (1404) of the current control TFT 1404 are L (1403) / W (1403): It may be set so as to satisfy L (1404) / W (1404) = 5 to 6000: 1.

  Note that the driving TFT 1403 operates in a saturation region and has a role of controlling a current value flowing through the light emitting element 1405. Further, the current control TFT 1404 operates in a linear region and has a role of controlling supply of current to the light emitting element 1405. It is preferable in the manufacturing process that both TFTs have the same conductivity type. In this embodiment mode, both TFTs are formed as n-channel TFTs. The driving TFT 1403 may be a depletion type TFT as well as an enhancement type. In the light emitting device of the present invention having the above structure, since the current control TFT 1404 operates in a linear region, a slight change in Vgs of the current control TFT 1404 does not affect the current value of the light emitting element 1405. That is, the current value of the light emitting element 1405 can be determined by the driving TFT 1403 operating in the saturation region. With the above structure, luminance unevenness of a light-emitting element due to variation in TFT characteristics can be improved, and a light-emitting device with high image quality can be provided.

  In the pixel shown in FIGS. 6A to 6D, the switching TFT 1401 controls input of a video signal to the pixel. When the switching TFT 1401 is turned on, a video signal is input into the pixel. Then, the voltage of the video signal is held in the capacitor element 1402. 6A and 6C illustrate the structure in which the capacitor element 1402 is provided, the present invention is not limited to this, and the capacity for holding the video signal is sufficient with the capacity value of the gate capacity or the like. In that case, the capacitor 1402 is not necessarily provided.

  The structure of the pixel shown in FIG. 6B is the same as that of the pixel shown in FIG. 6A except that a TFT 1406 and a scanning line 1415 are added. Similarly, the pixel configuration illustrated in FIG. 6D is the same as the pixel configuration illustrated in FIG. 6C except that a TFT 1406 and a scanning line 1415 are added.

  The TFT 1406 is controlled to be turned on or off by a newly arranged scanning line 1415. When the TFT 1406 is turned on, the charge held in the capacitor element 1402 is discharged, and the current control TFT 1404 is turned off. That is, the arrangement of the TFT 1406 can forcibly create a state where no current flows through the light-emitting element 1405. Therefore, the TFT 1406 can be called an erasing TFT. 6B and 6D can start the lighting period simultaneously with or immediately after the start of the writing period without waiting for signal writing to all the pixels. Therefore, the duty ratio can be improved.

  In the pixel illustrated in FIG. 6E, a signal line 1410, a power supply line 1411 are arranged in the column direction, and a scanning line 1414 is arranged in the row direction. In addition, the pixel includes a switching TFT 1401, a driving TFT 1403, a capacitor element 1402, and a light emitting element 1405. The structure of the pixel shown in FIG. 6F is the same as that of the pixel shown in FIG. 6E except that a TFT 1406 and a scanning line 1415 are added. Note that the duty ratio of the structure in FIG. 6F can also be improved by the arrangement of the TFT 1406.

  As described above, the present invention can employ various pixel circuits. In particular, when a thin film transistor is formed from an amorphous semiconductor film, it is preferable to increase the size of the semiconductor film of the driving TFT 1403. Therefore, the pixel circuit is preferably a top emission type in which light from a layer containing an organic compound is emitted from the sealing substrate side.

  Such an active matrix light-emitting device is considered to be advantageous in that it can be driven at a low voltage because a TFT is provided in each pixel when the pixel density is increased.

  In this embodiment mode, an active matrix light-emitting device in which each pixel is provided with each TFT has been described; however, the present invention can also be applied to a passive matrix light-emitting device. A passive matrix light-emitting device has a high aperture ratio because a TFT is not provided for each pixel. In the case of a light-emitting device in which light emission is emitted to both sides of a layer containing an organic compound, the aperture ratio increases when a passive matrix light-emitting device is used.

  Next, the case where a diode is provided as a protection circuit in the scan line and the signal line will be described using the equivalent circuit illustrated in FIG.

  In FIG. 7, a switching TFT 1401, a driving TFT 1403, a capacitor element 1402, and a light emitting element 1405 are provided in the pixel portion 1500. The signal line 1410 is provided with diodes 1561 and 1562. Like the switching TFT 1401 or the driving TFT 1403, the diodes 1561 and 1562 are manufactured based on the above embodiment mode, and include a gate electrode, a semiconductor layer, a source electrode, a drain electrode, and the like. The diodes 1561 and 1562 operate as diodes by connecting a gate electrode and a drain electrode or a source electrode.

  Common potential lines 1554 and 1555 connected to the diode are formed in the same layer as the gate electrode. Therefore, in order to connect to the source electrode or the drain electrode of the diode, it is necessary to form a contact hole in the gate insulating layer.

  A diode provided in the scan line 1414 has a similar structure.

  Thus, according to the present invention, the protection diode provided in the input stage can be formed simultaneously with the TFT. Note that the position where the protective diode is formed is not limited to this, and the protective diode can be provided between the driver circuit and the pixel.

  This embodiment can be combined with any of the structures of Embodiments 1 to 4 as appropriate.

  Further, by combining the protection circuits, the light emitting device of the present invention can be improved in reliability.

(Embodiment 6)
FIG. 8A illustrates an example of a structure of the light-emitting device of the present invention. FIG. 8A is a part of a cross-sectional view of a pixel portion of a passive matrix light-emitting device having a forward tapered structure. 8A includes a substrate 200, a first electrode 201 of a light-emitting element, a partition 202, a layer 203 containing an organic compound, a second electrode 204 of the light-emitting element, and a counter substrate 207. including.

  A portion to be a pixel is a portion in which a layer 203 containing an organic compound is sandwiched between the first electrode 201 and the second electrode 204 of the light-emitting element. The first electrode 201 and the second electrode 204 are formed in a stripe shape orthogonal to each other, and a portion to be a pixel is formed at an intersecting portion. The partition 202 is formed in parallel with the second electrode 204, and a portion to be a pixel is insulated from a portion to be another pixel having the same first electrode 201 by the partition 202.

  In this embodiment mode, Embodiment Mode 2 can be referred to for the specific material and structure of the light-emitting element including the first electrode 201, the second electrode 204, and the layer 203 containing an organic compound.

  In addition, the substrate 200, the partition 202, and the counter substrate 207 in FIG. 8A correspond to the substrate 50, the partition 65, and the counter substrate 94 in Embodiment 3, respectively, and the configuration, materials, and effects thereof are described in Embodiment 3. Since this is the same, repeated description will be omitted. Refer to the description in Embodiment Mode 3.

  In the light emitting device, a protective film 210 is formed in order to prevent intrusion of moisture and the like, and a counter substrate 207 such as a ceramic material such as glass, quartz, alumina, or a synthetic material is fixed with an adhesive 211 for sealing. The external input terminal portion is connected using a flexible printed wiring board 213 through an anisotropic conductive film 212 when connected to an external circuit. In addition to the protective film 210 formed of silicon nitride, the protective film 210 may be formed of a laminate of carbon nitride and silicon nitride as a structure that increases gas barrier properties while reducing stress.

  FIG. 8B shows a module formed by connecting an external circuit to the panel 10. The module has a flexible printed wiring board 25 fixed to the external input terminal portions 18 and 19 and is electrically connected to an external circuit board 29 on which a power supply circuit and a signal processing circuit are formed. In addition, the method of mounting the driver IC 28 which is one of the external circuits may be either the COG method or the TAB method. FIG. 8B shows a state where the driver IC 28 which is one of the external circuits is mounted using the COG method. The signal processing circuit and the driver IC 28 formed on these external circuit boards are light emitting element control circuits. Light emitting devices and electronic devices equipped with these control circuits are turned on and off of the light emitting elements or controlled by the control circuit. Various images can be displayed on the pixel unit 23 by the control.

  Note that the panel and the module correspond to one mode of the light-emitting device of the present invention, and both are included in the category of the present invention.

  The light-emitting device of the present invention as described above includes the light-emitting element described in Embodiment 2 in which the stilbene derivative described in Embodiment 1 is included in a layer including an organic compound as a light-emitting element included in the pixel portion. Thus, the light-emitting device has improved power consumption and display quality in the pixel portion. In addition, the light-emitting device of the present invention includes the light-emitting element described in Embodiment 2 that includes the stilbene derivative described in Embodiment 1 in a layer including an organic compound as a light-emitting element that forms a pixel portion. This light-emitting device has improved power consumption and display quality.

(Embodiment 7)
A representative example of the electronic apparatus of the present invention will be described with reference to FIG. An electronic device according to the present invention includes at least a light-emitting element including the stilbene derivative described in Embodiment 1 or the light-emitting element described in Embodiment 2, and a control circuit for controlling the light-emitting element. Examples of the electronic device of the present invention include a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio component, etc.), a computer, a game device, a portable information terminal (mobile computer, A mobile phone, a portable game machine, an electronic book, etc.), and an image playback apparatus (specifically, a digital versatile disc (DVD)) provided with a recording medium, and a display capable of displaying the image Apparatus).

  FIG. 9A shows a light-emitting device, such as a television receiver or a personal computer monitor. These include a housing 2001, a display portion 2003, a speaker portion 2004, and the like. Since the light-emitting device of the present invention includes the light-emitting element including the stilbene derivative described in Embodiment 1 which has a large energy gap or electron transport property in the display portion 2003, the light-emitting device has low power consumption and improved display quality. is there. In order to increase contrast, the pixel portion may be provided with a polarizing plate or a circular polarizing plate. For example, a film may be provided on the sealing substrate in the order of a 1 / 4λ plate, a 1 / 2λ plate, and a polarizing plate. Further, an antireflection film may be provided on the polarizing plate.

  FIG. 9B illustrates a mobile phone that can be viewed on television. This includes a main body 2101, a housing 2102, a display unit 2103, an audio input unit 2104, an audio output unit 2105, operation keys 2106, an antenna 2108, and the like. The mobile phone of the present invention is a mobile phone with low power consumption and improved display quality because the display portion 2103 includes the light-emitting element including the stilbene derivative described in Embodiment 1, which has a large energy gap or electron transport properties. is there.

  FIG. 9C illustrates a computer. This includes a main body 2201, a case 2202, a display portion 2203, a keyboard 2204, an external connection port 2205, a pointing mouse 2206, and the like. The computer of the present invention is a computer with low power consumption and improved display quality because the display portion 2203 includes the light-emitting element including the stilbene derivative described in Embodiment 1, which has a large energy gap or electron transport properties. Although FIG. 9C illustrates a notebook computer, the present invention can also be applied to a desktop computer or the like.

  FIG. 9D illustrates a mobile computer. This includes a main body 2301, a display portion 2302, a switch 2303, operation keys 2304, an infrared port 2305, and the like. Since the mobile computer of the present invention includes the light-emitting element including the stilbene derivative described in Embodiment Mode 1 which has a large energy gap or an electron transport property in the display portion 2302, the mobile computer has low power consumption and improved display quality. is there.

  FIG. 9E illustrates a portable game machine. This includes a housing 2401, a display portion 2402, a speaker portion 2403, operation keys 2404, a recording medium insertion portion 2405, and the like. The portable game machine of the present invention includes a light-emitting element including the stilbene derivative described in Embodiment Mode 1 having a large energy gap and an electron transport property in the display portion 2402, and thus has low power consumption and improved display quality. Type game machine.

  As described above, the applicable range of the present invention is so wide that it can be used for electronic devices in various fields.

  This embodiment can be combined with any of the structures of Embodiments 1 to 6 as appropriate.

(Synthesis Example 1)
Method for synthesizing 3,3′-di (phenanthren-9-yl) stilbene (DPNS)

  A method for synthesizing 3,3′-di (phenanthrene-9-yl) stilbene (DPNS), which is a stilbene derivative of the present invention represented by the following structural formula (4), will be described.

[Step 1] Synthesis of 3-bromobenzyltriphenylphosphonium bromide 25.0 g (100.0 mmol) of 3-bromobenzyl triphenyl and 100 mL of acetone were placed in a 200 mL Erlenmeyer flask, and 27.6 g (105.0 mmol) of triphenylphosphine was added. After that, the mixture was stirred at room temperature for about 24 hours. After the reaction, the precipitate in the reaction mixture was collected by suction filtration to obtain 45.57 g of a white powder of 3-bromobenzyltriphenylphosphonium bromide as a target product in a yield of 89%. The synthesis scheme of 3-bromobenzyltriphenylphosphonium bromide is shown below.

[Step 2] Synthesis of 3,3′-dibromostilbene 22.6 g (44.08 mmol) of 3-bromobenzyltriphenylphosphonium bromide synthesized in Step 1 and 9.79 g (52.90 mmol) of 3-bromobenzaldehyde were mixed into 500 mL The flask was placed in a flask and replaced with nitrogen. Subsequently, 150 mL of tetrahydrofuran (THF) was placed in the three-necked flask. Thereafter, 5.94 g (52.90 mmol) of tert-butoxy potassium dissolved in 50 mL of THF was added dropwise to the mixture while cooling with ice water. Then, it stirred at room temperature for about 12 hours and made it react. After the reaction, the reaction mixture was washed with water. The aqueous layer was extracted with ethyl acetate, and the organic layer was dried over magnesium sulfate. After drying, the mixture was filtered with suction, and the filtrate was concentrated. The obtained residue was washed with methanol, and the methanol suspension was collected as a solid by suction filtration. As a result, 5.90 g of a target white solid of 3,3′-dibromostilbene was obtained in a yield of 40%. The synthesis scheme of 3,3′-dibromostilbene is shown below.

[Step 3] Synthesis of DPNS 1.75 g (5.19 mmol) of 3,3′-dibromostilbene synthesized in Step 2, 2.63 g (11.8 mmol) of 9-phenanthreneboronic acid, 0.023 g (0. 103 mmol) and 0.221 g (0.727 mmol) of tris (o-tolyl) phosphine were put into a 100 mL three-necked flask and purged with nitrogen. Further, 40 mL of ethylene glycol dimethyl ether and 8 mL of an aqueous potassium carbonate solution (2.0 mol / L) were added, and the mixture was stirred at 90 ° C. for 6 hours to be reacted. After the reaction, the precipitate in the reaction mixture was collected by suction filtration. After filtration, the residue was recrystallized from chloroform and hexane to obtain 2.11 g of white solid in 76% yield. It was confirmed by nuclear magnetic resonance (NMR) that the obtained white solid was DPNS as the target product.

The ¹ H-NMR of DPNS obtained is shown below. Further, the ¹ H-NMR chart is shown in FIG.
¹ H-NMR (300 MHz, CDCl ₃ ); δ = 8.80-8.72 (m, 4H), 7.96-7.89 (m, 4H), 7.72-7.43 (m, 18H) ), 7.28 (s, 2H)

  A synthesis scheme of DPNS is shown below.

  In addition, when the decomposition temperature (Td) of DPNS was measured with a differential thermothermal gravimetric simultaneous measurement apparatus (Seiko Denshi Co., Ltd., TG / DTA320 type), it was found to be 396.4 ° C. and DPNS showed a high Td. It was.

  FIG. 11 shows an absorption spectrum of DPNS in a toluene solvent, and FIG. 13 shows an absorption spectrum of a thin film. FIG. 12 shows an emission spectrum of DPNS in a toluene solution, and FIG. 14 shows an emission spectrum in a thin film state. 11 and 13, the vertical axis represents absorption intensity (arbitrary unit), and the horizontal axis represents wavelength (nm). 12 and 14, the vertical axis represents the emission intensity (arbitrary unit), and the horizontal axis represents the wavelength (nm). The peak wavelength of light emission of DPNS was 355 nm and 375 nm (excitation wavelength: 320 nm) in a solution state using toluene as a solvent, and 410 nm (excitation wavelength: 308 nm) in a thin film state, and it was found that blue light emission was obtained.

Using the absorption spectrum data of FIG. 13, the absorption edge was determined by tauc plot, and the energy gap of DPNS was determined with the energy at the absorption edge as the energy gap. Since the energy gap of 9,10-diphenylanthracene exhibiting typical blue emission is 2.9 eV, it was found that DPNS has a very large energy gap. The HOMO level in the thin film state was −5.9 eV as a result of measurement by atmospheric photoelectron spectroscopy (manufactured by Riken Keiki Co., Ltd., AC-2). The LUMO level obtained from the HOMO level and the energy gap was -2.4 eV.

  In addition, the optimal molecular structure in the ground state of DPNS was calculated by B3LYP / 6-311 (d, p) of density functional theory (DFT). DFT is used in this calculation because it has better calculation accuracy than the Hartree-Fock (HF) method, which does not take into account electronic correlation, and the calculation cost is lower than the perturbation method (MP) method, which is the same level of calculation accuracy. did. The calculation was performed using a high performance computer (HPC) (manufactured by SGI, Altix 3700 DX). The value of the HOMO level of DPNS obtained from this calculation result was −5.85 eV.

  In addition, DPNS singlet excitation energy (energy gap) was calculated by applying B3LYP / 6-311 (d, p) of time-dependent density functional theory (TDDFT) in the molecular structure optimized by DFT. However, the singlet excitation energy was calculated to be 3.54 eV.

(Synthesis Example 2)
Method for synthesizing 4,4′-di (phenanthren-9-yl) stilbene (DPNS2)

  A method for synthesizing 4,4′-di (phenanthren-9-yl) stilbene (DPNS2), which is a stilbene derivative of the present invention represented by the following structural formula (5), will be described.

[Step 1] Synthesis of 4-bromobenzyltriphenylphosphonium bromide 25.36 g (101.5 mmol) of 4-bromobenzyltriphenyl bromide and 100 mL of acetone were placed in a 200 mL Erlenmeyer flask, and 29.28 g (111.6 mmol) of triphenylphosphine was added. After that, the mixture was stirred at room temperature for about 24 hours. After the reaction, the precipitate in the reaction mixture was collected by suction filtration to obtain 50 g of a white powder of 4-bromobenzyltriphenylphosphonium bromide, which was the target product, in a yield of 96%. The synthesis scheme of 4-bromobenzyltriphenylphosphonium bromide is shown below.

[Step 2] Synthesis of 4,4'-dibromostilbene 48.05 g (93.80 mmol) of 4-bromobenzyltriphenylphosphonium bromide synthesized in Step 1 and 20.83 g (112.6 mmol) of 4-bromobenzaldehyde were added to 1 L of three liters. The flask was placed in a flask and replaced with nitrogen. Subsequently, 300 mL of tetrahydrofuran (THF) was placed in the three-necked flask. Thereafter, 12.63 g (112.56 mmol) of tert-butoxy potassium dissolved in 100 mL of THF was added dropwise to the mixture while cooling with ice water. Then, it stirred at room temperature for about 12 hours and made it react. After the reaction, the reaction mixture was washed with water. The aqueous layer was extracted with ethyl acetate, and the organic layer was dried over magnesium sulfate. After drying, the mixture was filtered with suction, and the filtrate was concentrated. The obtained residue was washed with methanol, and the methanol suspension was recovered as a solid by suction filtration. As a result, 10.77 g of a target white solid of 4,4′-dibromostilbene was obtained in a yield of 34%. The synthesis scheme of 4,4′-dibromostilbene is shown below.

[Step 3] Synthesis of DPNS2 0.84 g (2.37 mmol) of 4,4′-dibromostilbene synthesized in Step 2, 1.2 g (5.40 mmol) of 9-phenanthreneboronic acid, 0.0053 g (0. 024 mmol) and 0.050 g (0.163 mmol) of tris (o-tolyl) phosphine were put into a 100 mL three-necked flask and purged with nitrogen. Thereafter, 15 mL of ethylene glycol dimethyl ether and 3.5 mL of an aqueous potassium carbonate solution (2.0 mol / L) were further added, followed by stirring at 90 ° C. for 8 hours for reaction. After the reaction, the precipitate in the reaction mixture was collected by suction filtration. After filtration, the residue was recrystallized with chloroform and hexane to obtain 0.86 g of white solid with a yield of 68%. It was confirmed by nuclear magnetic resonance (NMR) that the obtained white solid was DPNS2, which was the target product.

The ¹ H-NMR of DPNS2 obtained is shown below. Further, the ¹ H-NMR chart is shown in FIG.
¹ H-NMR (300 MHz, CDCl ₃ ); δ = 8.81-8.73 (m, 4H), 8.02-7.91 (m, 4H), 7.74-7.57 (m, 18H) ), 7.34 (s, 2H)

  A synthesis scheme of DPNS2 is shown below.

  In addition, when the decomposition temperature (Td) of DPNS2 was measured with a differential thermothermal gravimetric simultaneous measurement apparatus (Seiko Denshi Co., Ltd., TG / DTA320 type), it was 416.6 ° C., and it was found that DPNS2 shows high Td. It was.

  FIG. 16 shows an absorption spectrum of DPNS2 in a solution using toluene as a solvent, and FIG. 18 shows an absorption spectrum in a thin film state. Further, FIG. 17 shows an emission spectrum of DPNS2 in a toluene solution state, and FIG. 19 shows an emission spectrum of a thin film state. 16 and 18, the vertical axis represents absorption intensity (arbitrary unit), and the horizontal axis represents wavelength (nm). 17 and 19, the vertical axis represents the emission intensity (arbitrary unit), and the horizontal axis represents the wavelength (nm). The maximum emission wavelength of DPNS2 was 420 nm (excitation wavelength 348 nm) in a solution state using toluene as a solvent, and 437 nm (excitation wavelength 344 nm) in a thin film state, and it was found that blue light emission was obtained.

Using the absorption spectrum data of FIG. 18, the absorption edge was obtained by tauc plot, and the energy gap of DPNS2 was obtained by using the energy at the absorption edge as the energy gap, which was 3.2 eV. Since the energy gap of 9,10-diphenylanthracene exhibiting typical blue light emission is 2.9 eV, it was found that DPNS2 has a very large energy gap. The HOMO level in the thin film state was −5.9 eV as a result of measurement by atmospheric photoelectron spectroscopy (manufactured by Riken Keiki Co., Ltd., AC-2). The LUMO level obtained from the HOMO level and the energy gap was −2.7 eV.

  The optimal molecular structure of DPNS2 in the ground state was calculated by the same method as in Synthesis Example 1 above. The value of the HOMO level of DPNS2 obtained from this calculation result was −5.59 eV.

  Further, when the singlet excitation energy (energy gap) of DPNS2 was calculated by the same method as in Synthesis Example 1, the singlet excitation energy was calculated to be 3.34 eV.

  In this example, a manufacturing method and characteristics of a light-emitting element using DPNS as a host material of a light-emitting layer will be described.

  The light-emitting element is formed over a glass substrate, and ITSO is formed with a thickness of 110 nm as a first electrode in order from the glass substrate side. The ITSO was formed by sputtering. In the present invention, the first electrode was processed into a 2 mm × 2 mm square shape. Next, as a pretreatment for forming a light-emitting element over the first electrode, the substrate surface was washed with a porous resin (typically, PVA (polyvinyl alcohol), nylon, or the like). Furthermore, heat treatment was performed at 200 ° C. for 1 hour, and UV ozone treatment was performed for 370 seconds.

Next, 20 nm of CuPC was formed as a hole injection layer, and then 40 nm of BSPB was formed as a hole transport layer. On these laminated films, a co-deposited film of DPNS and TBP was formed to a thickness of 30 nm as a light emitting layer. The weight ratio of DPNS and TBP was 1: 0.01. Further, 30 nm of Alq ₃ was formed as the electron transport layer, and 1 nm of calcium fluoride (CaF ₂ ) was formed as the electron injection layer. Finally, Al was formed as a second electrode with a film thickness of 200 nm to complete the device. Note that the films from the hole injection layer to the second electrode were all formed by a vacuum evaporation method using resistance heating.

  The current density-luminance characteristics of the fabricated device are shown in FIG. 20, the luminance characteristics-current efficiency is shown in FIG. 21, and the voltage-luminance characteristics are shown in FIG. From these results, it can be seen that the light-emitting element using DPNS which is the stilbene derivative of the present invention has sufficient luminance at a low voltage and efficiently converts current into light. That is, it can be said that a light-emitting element using DPNS which is a stilbene derivative of the present invention has favorable characteristics. The light emitted from the fabricated device was a good blue color with CIE chromaticity coordinates (x, y) = (0.15, 0.20).

Note that Alq ₃ (light emission is green) having an energy gap smaller than DPNS is used as an electron transport layer in contact with the light emission layer. However, since the CIE chromaticity coordinate is (x, y) = (0.15, 0.20) and shows a good blue color, it can be seen that Alq ₃ does not emit light. From this, it can be seen that DPNS does not transport holes, that is, has an electron transport property.

  As described above, the light-emitting element of this example uses DPNS, which is the stilbene derivative described in Embodiment Mode 1, as the host material of the light-emitting layer. Since the energy gap of DPNS is large, light emission of TBP, which is the light-emitting material, is efficient. It was possible to obtain a blue light-emitting element with good color purity.

In addition, the light-emitting element of this example uses DPNS which is the stilbene derivative described in Embodiment 1 as a host material of the light-emitting layer. Since DPNS has an electron transporting property, Alq is used as an electron transport layer. _Even in the device using ₃ , light emission from Alq ₃ did not appear, and a blue light-emitting device with good color purity could be obtained.

  In this example, a manufacturing method and characteristics of a light-emitting element using DPNS2 as a host material of a light-emitting layer will be described.

  The light-emitting element is formed over a glass substrate, and ITSO is formed with a thickness of 110 nm as a first electrode in order from the glass substrate side. The ITSO was formed by sputtering. In the present invention, the first electrode was processed into a 2 mm × 2 mm square shape. Next, as a pretreatment for forming a light-emitting element over the first electrode, the substrate surface was washed with a porous resin (typically, PVA (polyvinyl alcohol), nylon, or the like). Furthermore, heat treatment was performed at 200 ° C. for 1 hour, and UV ozone treatment was performed for 370 seconds.

Next, 20 nm of CuPC was formed as a hole injection layer, and then 40 nm of BSPB was formed as a hole transport layer. On these laminated films, a co-evaporated film of DPNS2 and TBP was formed to a thickness of 30 nm as a light emitting layer. The weight ratio of DPNS2 and TBP was 1: 0.01. Further, 30 nm of Alq ₃ was formed as the electron transport layer, and 1 nm of calcium fluoride (CaF ₂ ) was formed as the electron injection layer. Finally, Al was formed as a second electrode with a film thickness of 200 nm to complete the device. Note that the films from the hole injection layer to the second electrode were all formed by a vacuum evaporation method using resistance heating.

  FIG. 23 shows the current density-luminance characteristics of the fabricated device, FIG. 24 shows the luminance-current efficiency characteristics, and FIG. 25 shows the voltage-luminance characteristics. From these results, it can be seen that the light-emitting element using DPNS2, which is the stilbene derivative of the present invention, has a sufficient luminance at a low voltage and efficiently converts current into light. That is, it can be said that a light-emitting element using DPNS2, which is a stilbene derivative of the present invention, has favorable characteristics. The light emitted from the fabricated device was a good blue color with CIE chromaticity coordinates (x, y) = (0.15, 0.22).

Note that Alq ₃ (light emission is green) having an energy gap smaller than DPNS2 in contact with the light-emitting layer as an electron transporting layer is used. However, since the CIE chromaticity coordinates are (x, y) = (0.15, 0.22) indicating a good blue color, it can be seen that Alq ₃ does not emit light. From this, it can be seen that DPNS2 does not transport holes, that is, has an electron transport property.

  As described above, the light-emitting element of this example uses DPNS2, which is the stilbene derivative described in Embodiment 1, as the host material of the light-emitting layer. Since the energy gap of DPNS2 is large, light emission of TBP, which is the light-emitting material, is efficient. It was possible to obtain a blue light-emitting element with good color purity.

The light-emitting element of this example uses DPNS2, which is the stilbene derivative described in Embodiment 1, as a host material of the light-emitting layer. Since DPNS2 has an electron transporting property, Alq is used as an electron transport layer. _Even in the device using ₃ , light emission from Alq ₃ did not appear, and a blue light-emitting device with good color purity could be obtained.

FIG. 14 illustrates a light-emitting element of the present invention. 9A to 9D are cross-sectional views illustrating a method for manufacturing an active matrix light-emitting device of the present invention. 9A to 9D are cross-sectional views illustrating a method for manufacturing an active matrix light-emitting device of the present invention. 1 is a cross-sectional view of an active matrix light-emitting device of the present invention. 2A and 2B are a top view and a cross-sectional view of a light-emitting device of the present invention. FIG. 14 illustrates an example of a pixel circuit of a light-emitting device of the present invention. FIG. 9 illustrates an example of a protection circuit of a light-emitting device of the present invention. 2A and 2B are a top view and a cross-sectional view of a passive matrix light-emitting device of the present invention. FIG. 10 illustrates an electronic device to which the present invention is applicable. NMR chart of DPNS. Absorption spectrum of DPNS in solution. The emission spectrum in the solution state of DPNS. Absorption spectrum of DPNS in a thin film state. The emission spectrum in the thin film state of DPNS. NMR chart of DPNS2. Absorption spectrum of DPNS2 in solution. The emission spectrum in the solution state of DPNS2. Absorption spectrum of DPNS2 in a thin film state. The emission spectrum in the thin film state of DPNS2. Current density-luminance characteristics of devices using DPNS. Luminance-current efficiency characteristics of devices using DPNS. Voltage-luminance characteristics of elements using DPNS. The current density-luminance characteristic of the element using DPNS2. Luminance-current efficiency characteristics of devices using DPNS2. Voltage-luminance characteristics of the device using DPNS2.

Explanation of symbols

100 Insulator 101 Electrode 102 Layer 103 Electrode

Claims (8)

A stilbene derivative represented by the following general formula (1).

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ represent hydrogen or a substituent represented by the following structural formula (2), and R ¹ , R ² , R ³ , R ⁴ , R ⁵ At least one of them is a substituent represented by the following structural formula (2), wherein R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each represented by hydrogen or the following structural formula (2). And at least one of R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ is a substituent represented by the following structural formula (2).

A stilbene derivative represented by the following general formula (3).

(In the formula, n represents an integer of 0 to 2, and m represents an integer of 1 to 2.) A stilbene derivative represented by the following structural formula (4).

A stilbene derivative represented by the following structural formula (5).

  The material for light emitting elements containing the stilbene derivative as described in any one of Claims 1 thru | or 4.   The light emitting element containing the stilbene derivative as described in any one of Claims 1 thru | or 4.   The light emitting element which uses the stilbene derivative as described in any one of Claims 1 thru | or 4 for the host material of a light emitting layer.   An electronic device having a light-emitting element including the stilbene derivative according to any one of claims 1 to 4.

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