Light emitting element and manufacturing method thereof, and light emitting device using the light emitting element

Light-emitting element and its manufacturing method, and light-emitting device using the light-emitting element

The present invention relates to a light-emitting element having a structure in which a plurality of layers are inserted between a pair of electrodes, and particularly relates to a multilayer structure.

A light-emitting device using an electroluminescent element (light-emitting element) to emit light has attracted attention as, for example, a device for display or lighting.

As a light-emitting element used in a light-emitting device, a structure having multiple layers inserted between a pair of electrodes is known, and each layer includes a material such as a light-emitting or carrier-transporting material.

In the case of this light-emitting element, one electrode is used as an anode and the other electrode is used as a cathode, holes injected from the anode side and electrons injected from the cathode side recombine to form molecules in an excited state, and emit light when the molecules return to the ground state . The emitted light is extracted to the outside by one or two of the pair of electrodes.

As for the manufacturing method of the above-mentioned light-emitting element, it is generally known to form one of the electrodes, to form multiple layers thereon, and then to form the other electrode thereon.

In the case of manufacturing a light-emitting element in this manner, in a technique of forming an electrode after forming a multilayer, the multilayer is sometimes damaged so that good characteristics cannot be obtained. In the case of forming electrodes using sputtering, this phenomenon is particularly frequently observed. It is believed that this is because in the technique of forming electrodes using sputtering, high-energy atoms damage the layer.

Therefore, a light-emitting element including a structure that is less damaged even in the case of forming electrodes using sputtering, and a method of manufacturing the same, have been developed.

For example, Japanese Patent Literature 1 or Patent Literature 2 shows that damage to the organic layer can be suppressed by providing a layer including phthalocyanine, which damage is caused by sputtering during deposition. In addition, Japanese Patent Document 3 also discloses that damage to the organic layer can be suppressed by providing a layer including AgLi, which damage is caused by sputtering during deposition.

However, the method disclosed in Patent Document 1 or Patent Document 2 has problems such as the addition of processing steps in order to provide a layer including phthalocyanine between the electron transport layer and the electron injection electrode, and since the phthalocyanine easily absorbs long The light in the wavelength range causes the luminous efficiency of red light to decrease. In addition, the method disclosed in Patent Document 3 has the following problems. For example, as the film thickness of AgLi becomes thicker, the transmittance of light becomes lower, thereby reducing the external extraction efficiency of emitted light.

[Patent Document 1] Japanese Patent Laid-Open No. 2002-75658

[Patent Document 2] Japanese Patent Laid-Open No. 2002-359086

[Patent Document 3] Japanese Patent Laid-Open No. 2003-249357

An object of the present invention is to provide a light-emitting element formed in order to suppress damage due to damage to a layer including an organic material due to sputtering during deposition. In addition, an object of the present invention is to provide a light-emitting element formed to suppress damage, such as a short circuit between electrodes, which damages a layer including an organic material due to sputtering during deposition.

In order to suppress damage to a layer including an organic material that may be caused by sputtering during deposition, the light-emitting element according to the present invention is provided with a layer including a metal oxide between a pair of electrodes.

The light-emitting element according to the present invention has a layer including an organic material between the first electrode and the second electrode, and also has a layer including a metal oxide between the second electrode and the layer including the organic material, wherein these electrodes and Layer so that the second electrode is formed later than the first electrode.

The layer including the organic material may be a single layer or multiple layers. Preferably, a material such as a high-carrier (electron or hole) transport material and a high-carrier injection material are combined to form a layer including an organic material so as to form a light-emitting area in a portion away from the first electrode and the second electrode . Also, the layer including the organic material may include a metal element such as lithium or magnesium, or other metal elements in a part thereof.

In addition, specific examples of metal oxides include molybdenum oxide (MoOx), vanadium oxide (VOx), ruthenium oxide (RuOx), tungsten oxide (WOx), manganese oxide (MnOx), etc., and it is preferable that these are formed by evaporation .

In the case of the light-emitting element according to the present invention, as described above, it has a structure in which a layer including a metal oxide is provided between a second electrode and a layer including an organic material, and the second electrode may be formed by sputtering.

Therefore, as the second electrode, it becomes easy to use materials deposited by sputtering easier than evaporation, such as indium tin oxide (ITO), silicon-containing indium tin oxide (ITSO) or mixed with 2 to 20% Zinc oxide (ZnO), indium oxide, and IZO (Indium Zinc Oxide), and the material used to form the second electrode has a wide selection range.

In addition, even in the case of a light-emitting element having a structure of a film formed by sputtering between the second electrode and a layer including a metal oxide, it is possible to suppress the damage caused by sputtering in the same manner as described above. Damage to layers including organic materials caused by deposition. In this case, it is not always necessary to form the second electrode by sputtering. As long as the light-emitting element has a layer including an organic material, a layer including a metal oxide, and a layer formed by sputtering are sequentially stacked, the advantages of the present invention can be obtained.

According to the present invention, it is possible to obtain a light-emitting element in which defects due to deposition by sputtering are suppressed. In addition, it is possible to obtain a light-emitting element that suppresses defects due to sputtering deposition and also suppresses short circuits between electrodes.

[Example Mode]

The light-emitting element according to the present invention has a layer including an organic material between a pair of electrodes. The layer including the organic material has a single layer or multiple layers. Preferably, a layer including a high carrier injection material and a layer including a high carrier transport material are combined to form a layer including an organic material, so as to form a light-emitting area away from the electrode, that is, to recombine carriers in a portion away from the electrode.

With reference to FIGS. 2A to 2C, one mode of the light-emitting element according to the present invention will be explained below.

In this embodiment mode, a light-emitting element 210 is provided on a substrate 200 for supporting the light-emitting element 210, and the light-emitting element 210 has a first electrode 201, and first to fifth layers sequentially stacked on the first electrode 201 202 to 206 and the second electrode 207 also provided thereon, so that the first electrode 201 serves as a cathode and the second electrode 207 serves as an anode.

As the substrate 200, for example, glass or plastic can be used. As long as the material is used for support in the manufacturing process of the light-emitting element, other materials different from these can be used.

Preferably, the first electrode 201 is formed to include a material with a small work function (work function of 3.8 eV or less), such as metals, alloys, conductive compounds, or mixtures of these, which particularly include those belonging to the element in the periodic table. Group 1 or Group 2 elements, namely alkali metals such as lithium (Li) or cesium (Cs) and alkaline earth metals such as magnesium (Mg), calcium (Ca) or strontium (Sr), and alloys including this element, For example, aluminum alloy (Al:Li) or silver alloy (Mg:Ag). However, by providing a layer that is in contact with the first electrode 201 and has a function of promoting electron injection between the first electrode 201 and the second electrode 207, various conductive materials such as Al, Ag, indium tin can be used regardless of the size of the work function. Oxide (ITO) and ITO including silicon (Si) are used as the first electrode 201. However, in this regard, materials other than those mentioned in this embodiment may be used.

The first layer 202 is a layer including a high electron injection material, such as a compound of alkali metal or alkaline earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF) or calcium fluoride (CaF).₂). In addition, the first layer 202 may be a layer including a high electron transport material and an alkali metal or alkaline earth metal, for example, including Alq₃And magnesium (Mg) layer.

The second layer 203 is a layer including a high electron transport material, for example, a metal complex having a quinoline moiety or a benzoquinoline moiety, such as tris(8-hydroxyquinoline) aluminum (abbreviated as: Alq₃), tris(5-methyl-8-hydroxyquinoline) aluminum (abbreviated as: Almq₃), two (10-benzohydroxy[h]-hydroxyquinoline) beryllium (abbreviated as: BeBq₂) Or bis(2-methyl-8-hydroxyquinoline)-4-phenylphenolato-aluminum (abbreviated as: BAlq). In addition, metal complexes having ligands such as oxazole or thiazole, for example, bis[2-(2-hydroxyphenyl)-benzoxazolato] zinc (abbreviated as: Zn( BOX)₂) Or bis[2-(2-hydroxyphenyl)-benzothiazolato] zinc (abbreviated as: Zn(BTZ)₂). Moreover, in addition to metal complexes, 2-(4-biphenyl)-5(4-tert-butylbenzene)-1,3,4-oxadiazole (abbreviated as: PBD), 1 ,3-bis[5-(p-tert-butylbenzene)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as: OXD-7), 3-(4-tert-butylbenzene) Benzene)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole (abbreviated as: TAZ), 3-(4-tert-butylbenzene)-4-(4- Ethylbenzene)-5-(4-biphenyl)-1,2,4-triazole (abbreviated as: p-EtTAZ), bathophenanthroline (abbreviated as: BPhen) and bathocuproin ( Abbreviated as: BCP). However, in this regard, materials other than the materials mentioned in this embodiment mode can be used.

The third layer 204 is a layer including a high luminescent material. For example, high luminescent materials such as N,N'-dimethylquinacridone (abbreviated as: DMQd) or 2H-benzopyran-2-one (abbreviated as: coumarin) and, for example, three (8- Hydroxyquinoline) aluminum (abbreviated as: Alq₃) Or 9,10-bis(2-naphthyl)anthracene (abbreviated as: DNA) high carrier transport materials freely combine to form the third layer 204. However, as Alq₃DNA and DNA are also highly luminescent materials, so these materials are not often used as the third layer 204.

The fourth layer 205 is a layer including a high hole transport material, for example, an aromatic amine compound (ie, a compound having a benzene ring-nitrogen bond), such as 4,4-bis[N-(1-naphthyl)- N-phenyl-amino]-biphenyl (abbreviated as: α-NPD), 4,4'-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviated as : TPD), 4,4',4"-tris(N,N-biphenyl-amino)-triphenylamine (abbreviated as: TDATA), or 4,4',4"-tris[N-(3-form Phenyl)-N-phenyl-amino]-triphenylamine (abbreviated as: MTDATA). However, in this regard, materials other than the materials mentioned in this embodiment mode can be used.

The fifth layer 206 is a layer including metal oxides such as molybdenum oxide (MoOx), vanadium oxide (VOx), ruthenium oxide (RuOx), tungsten oxide (WOx), or manganese oxide (MnOx). By providing the layer including the metal oxide in this manner, it is possible to suppress damage to the layers (the first to fourth layers in this embodiment) each including the organic compound, which is used in the process of forming the second electrode 207 Caused by sputtering. In this embodiment mode, preferably, a layer including a metal oxide is formed by evaporation. In addition, preferably, the film thickness of the layer including the metal oxide is 10 nm or more. In order to suppress damage due to sputtering, it is effective to form a layer including a metal oxide to have the above-mentioned film thickness. Materials other than those mentioned in this embodiment mode can be used as the layer including metal oxide.

For example, the fifth layer 206 may be a layer including a metal oxide and a high hole transport material. The aforementioned materials such as α-NPD and TPD are cited as high-hole transport materials. By including the high-transmission material in this way, it becomes easy to inject holes into the fifth layer 206. In addition, by changing the thickness of the fifth layer 206 including the high-hole transport material to adjust the distance between the layer including the high-luminescence material (the third layer 204 in this embodiment) and the second electrode 207, it becomes It is easier to extract the light emission showing a better spectrum to the outside. This is because the increase in the driving voltage caused by making the thickness of the fifth layer 206 thicker can be reduced by including the high-hole transport material.

Moreover, in the case of forming a layer including a metal oxide having a film thickness of 100 nm or more, it is possible to suppress a short circuit between the first electrode 201 and the second electrode 207 due to, for example, the first electrode 201 or the second electrode 207 It is caused by protrusions formed on the film surface of the second electrode 207 or by foreign objects mixed between these electrodes. Since the metal oxide has high light transmission characteristics, the emitted light can be sufficiently extracted even when the film thickness becomes thicker.

Preferably, the second electrode 207 is formed to include a material having a large work function (work function of 4.0 eV or more), such as a metal, an alloy, a conductive compound, or a mixture of these. In particular, in addition to indium tin oxide (ITO), indium tin oxide containing silicon, and IZO (indium zinc oxide) mixed with indium oxide of 2 to 20% zinc oxide (ZnO), for example, Gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd) and Metal nitride (such as TiN) material. In this way, the second electrode 207 is formed using a conductive material that can be deposited by sputtering. However, in this respect, other materials different from the materials mentioned in this embodiment mode can be used.

In the light-emitting element according to the present invention, which has the structure described above, the current flows due to the potential difference generated between the first electrode 201 and the second electrode 207, and the third layer 204 is a layer including a high-luminescence material. In the middle, the hole and the electron recombine, and then emit light. In other words, the light-emitting element has such a structure that a light-emitting region is formed in the third layer 204. However, it is not necessary to use all of the third layer 204 as a light emitting region, and for example, the light emitting region may be formed only at the fourth layer 205 side or the second layer 203 side in the third layer 204.

The emitted light is extracted to the outside by one or both of the first electrode 201 and the second electrode 207. Therefore, one or both of the first electrode 201 and the second electrode 207 are formed to include a light-transmitting material.

In the case where the first electrode 201 and the second electrode 207 are formed to include a light-transmitting material, as shown in FIG. 2A, the emitted light is extracted from the substrate side and the side opposite to the substrate via the first electrode 201 and the second electrode 207. In the case where only the second electrode 207 is formed to include the light-transmitting material, and in the case where the first electrode 201 and the second electrode 207 are formed to include the light-transmitting material and a reflective film is provided on the side of the first electrode 201, as shown in FIG. 2B As shown, the emitted light is extracted from the side opposite to the substrate via the second electrode 207. In the case where only the first electrode 201 is formed to include the light-transmitting material, and in the case where the first electrode 201 and the second electrode 207 are formed to include the light-transmitting material and a reflective film is provided on the second electrode 207 side, as shown in FIG. 2C As shown, the emitted light is extracted from the substrate side via the first electrode 201.

The layer structure provided between the first electrode 201 and the second electrode 207 is not limited to the above-mentioned structure. A structure other than the above-mentioned structure may be used, as long as the structure provides a hole and electron recombination area in a portion away from the first electrode 201 and the second electrode 207 in order to suppress quenching caused by the preparation of the light-emitting area, and the metal Close to each other and the structure has a layer including metal oxide. In other words, the stacked structure is not particularly limited, and may include, for example, high electron transport materials, high hole transport materials, high electron injection materials, high hole injection materials, and bipolar materials (high electron and hole transport materials). Each layer of) is freely combined with a layer including a metal oxide to prepare the laminated structure. Moreover, the recombination area of carriers can be controlled by providing a layer including, for example, an extremely thin silicon dioxide film.

The above-mentioned light-emitting element is manufactured by forming the first electrode 201 on the substrate 200, sequentially laminating the first to fifth layers 202 to 206 thereon, and further forming the second electrode 207 thereon. Although the method of forming each layer is not particularly limited, it is preferable to use any one of evaporation, inkjet, and spin coating to form the layer.

Fig. 3 shows a specific example of the light-emitting element according to the present invention, which has a structure different from the above-mentioned structure. The first electrode 301 is provided on the substrate 300, and the first to fifth layers 302 to 306 are provided on the first electrode 301 by stacking sequentially. Also, a second electrode 307 is provided on the fifth layer 306.

Here, the first layer 302 is formed to include a high hole injection material, the second layer 303 is formed to include a high hole transport material, and the third layer 304 is formed to include a high carrier transport material, which includes light emitting Body, the fourth layer 305 is formed to include a high electron transport material. The fifth layer 306 is a layer including a metal oxide, and in addition, may include a high electron injection material, such as an alkali metal or alkaline earth metal, such as lithium or magnesium. Also in the case of the light-emitting element having this structure, it is possible to suppress damage to the layer including the organic compound due to sputtering deposition, as described above. When the light-emitting element has this structure, the first electrode 301 and the second electrode 307 function as an anode and a cathode, respectively. The light-emitting element shown in FIG. 3 is also one mode of the light-emitting element according to the present invention, and the structure of the light-emitting element according to the present invention is not limited to this.

In the light-emitting element thus described according to the present invention, damage to the layer including the organic material due to sputtering can be suppressed. In addition, by controlling the film thickness of the layer including the metal oxide, the short circuit between the electrodes can be suppressed. Moreover, in the light-emitting device to which the light-emitting element according to the present invention is applied, defects of the light-emitting element due to sputtering or short-circuit between electrodes are suppressed. For example, in a display device, a satisfactory display image can be obtained.

In this embodiment mode, the case where the electrode is formed by sputtering is explained. However, for example, even in the case of a light-emitting element having a structure in which a film is formed by sputtering between an electrode and a layer including a metal oxide, the following advantages can be obtained: The damage to the layer including the organic material caused by sputtering is suppressed. In either case, as long as the light-emitting element has a structure in which a layer including an organic material, a layer including a metal oxide, and a layer formed by sputtering are sequentially stacked, and the layer including the organic material is formed before the layer formed by sputtering is formed , It is possible to obtain the advantage of providing a layer including a metal oxide.

[Example 1]

The method of manufacturing the light-emitting element according to the present invention and the characteristics of the light-emitting element will be described below. The structure or manufacturing technology of the light-emitting element according to the present invention is not limited to this embodiment, and for example, the thickness or material of the film may be appropriately changed.

On the glass substrate, indium tin oxide (ITO) is deposited by sputtering to form the first electrode, and the deposited ITO contains an amorphous component as its main component. Then, after the ITO was etched so as to be separated into a plurality of elements, heat treatment was performed at 200°C for 1 hour. Also, after applying acrylic as a positive photoresist, exposure and development are performed to form a separation layer. After that, heat treatment was performed at 220°C for 1 hour.

Then, after wet cleaning, after UV ozone treatment, in 1×10^-6 Under a vacuum atmosphere of Pa, the glass substrate deposited with ITO was processed at 150°C for 30 minutes.

Next, 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviated as: BzOs) and lithium (Li) were co-deposited to form a first layer on the first electrode. Control the weight ratio of BzOs to Li to be 1:0.02. In addition, the film thickness of the first layer was controlled to 20 nm.

Next, deposit Alq on the first layer₃To form the second layer. Control the film thickness of the second layer to 20 nm.

Next, co-deposit Alq on the second layer₃And DMQD to form the third layer. Control Alq₃The weight ratio with DMQD is 1:0.01. In addition, the film thickness of the third layer was controlled to 40 nm.

Next, α-NPD is deposited on the third layer to form the fourth layer. The film thickness of the fourth layer is controlled to 40 nm.

In this way, layers (first to fourth layers) each including an organic material are formed on the first electrode. The materials included in each layer are not limited to the materials mentioned in this embodiment, and other materials may be used.

Next, molybdenum oxide as a metal oxide is deposited on the fourth layer to form the fifth layer. The film thickness of the fifth layer is controlled to 50 nm.

Next, ITO was deposited on the fifth layer by sputtering, thereby forming a second electrode. The substrate temperature during deposition (during plasma generation) is 40°C to 50°C. The deposited ITO contains an amorphous component as its main component. The film thickness of the second electrode is controlled to be 110 nm.

The characteristics of the light-emitting element thus manufactured according to the present invention are shown by the dots in FIG. 1. Figure 1 shows voltage-luminance characteristics, where the horizontal axis represents voltage (V) and the vertical axis represents brightness (cd/m²). Figure 1 shows the driving voltage (at this voltage, 1cd/m²The voltage of light emission or greater as the driving voltage) is approximately 5.5V. Fig. 4 shows voltage-current characteristics, in which the horizontal axis represents voltage (V) and the vertical axis represents current (mA). Figure 5 shows the brightness (cd/m²)-Current efficiency (cd/A) characteristics, where the horizontal axis represents brightness and the vertical axis represents current efficiency.

(Comparative example 1)

Hereinafter, a comparative example related to the light-emitting element according to the present invention shown in Example 1 will be described.

The light-emitting element of this comparative example has the following structure, which includes a mixed layer (20 nm) of BzOs and Li, and includes Alq₃Layer (20nm), including DMQD and Alq₃The mixed layer (40nm), the layer including α-NPD (40nm) and the layer (20nm) including CuPc are sequentially laminated on the first electrode including ITO, and the second electrode including ITO is further laminated thereon. In each case, ITO for the electrode was formed by sputtering in the same manner as described above. In addition, the weight ratio of BzOs to Li is 1:0.02, and Alq₃The weight ratio with DMQD is 1:0.01.

The characteristics of the light-emitting element of this comparative example are shown by the triangular points in FIG. 1. Figure 1 shows voltage-luminance characteristics, where the horizontal axis represents voltage (V) and the vertical axis represents brightness (cd/m²). Figure 1 shows the driving voltage (at this voltage, 1cd/m²The voltage of light emission or greater as the driving voltage) is approximately 13V. Fig. 4 shows voltage-current characteristics, in which the horizontal axis represents voltage (V) and the vertical axis represents current (mA). Figure 5 shows the brightness (cd/m²)-Current efficiency (cd/A) characteristics, where the horizontal axis represents brightness and the vertical axis represents current efficiency. The characteristics of the light-emitting element are obtained from the light emission extracted from the second electrode side.

As described above, the characteristics of the light-emitting elements of Example 1 and Comparative Example 1 showed the following items. In the case of the light-emitting element of the comparative example using CuPc, the driving voltage of the light-emitting element is very high (13V) due to damage to a part of the element (including the layer of organic material) caused by the technique of depositing ITO by sputtering However, the light-emitting element according to the present invention does not have this tendency. In other words, in the case of the light-emitting element according to the present invention, it is possible to more suppress the defects of the light-emitting element due to sputtering as compared with the case of the light-emitting element of the comparative example.

[Example 2]

In this embodiment, a light-emitting element having the same structure as that shown in Embodiment 1 will be explained, except that the fifth layer including molybdenum oxide has a film thickness different from that in Embodiment 1. The manufacturing method of the light-emitting element shown in this example is also the same as in Example 1. Therefore, the description of the manufacturing method is omitted.

As for the light-emitting element of this embodiment, the fifth layer including molybdenum oxide has a film thickness of 10 nm (Example 2-1), 100 nm (Example 2-2), and 200 nm (Example 2-3).

Fig. 6 shows the characteristics of the light-emitting element of this example. Figure 6 shows voltage-luminance characteristics, where the horizontal axis represents voltage (V) and the vertical axis represents brightness (cd/m²). Fig. 6 shows that in each case of the light-emitting elements represented by Examples 2-1, 2-2, and 2-3, the driving voltage (at this voltage is 1 cd/m²The voltage of light emission or greater as the driving voltage) is about 5V. Fig. 7 shows voltage-current characteristics, in which the horizontal axis represents voltage (V) and the vertical axis represents current (mA). Figure 8 shows the brightness (cd/m²)-Current efficiency (cd/A) characteristics, where the horizontal axis represents brightness and the vertical axis represents current efficiency. 6 to 8 show that when low voltage is applied, the characteristics of the light-emitting elements are comparable to each other regardless of the film thickness of the fifth layer, and indicate that when a higher voltage is applied, the fifth layer has a thicker film thickness. Light-emitting elements tend to show higher brightness. From this forward, it is thought that in the case of a light-emitting element having a thicker film thickness of the fifth layer, damage due to sputtering can be more suppressed. The characteristics of the light-emitting element are obtained from the light emitted from the second electrode side.

As described above, as for the light-emitting element shown in this embodiment, it was confirmed that even when the film thickness of the layer including the metal oxide is prepared thicker, satisfactory characteristics can be obtained. Therefore, by increasing the film thickness of the layer including the metal oxide, the short circuit between the electrodes can be suppressed. Also, as for the light-emitting element shown in this embodiment, it was determined that even when the film thickness of the layer including the metal oxide is thicker, the emitted light can be effectively extracted to the outside.

[Example 3]

In this embodiment, the structure of the light emitting device according to the present invention will be explained.

In each of FIGS. 9A to 9C, a portion surrounded by a dotted line is a transistor 11 provided for driving the light emitting element 12. The light emitting element 12 is formed to include the first electrode 13, the second electrode 14, and the light emitting layer 15 interposed between these electrodes. The first electrode 13 and the drain of the transistor 11 are electrically connected to each other by the wiring 17 extending through the first interlayer insulating films 16a to 16c. In addition, the light-emitting element 12 is separated from another light-emitting element provided adjacently by the separation layer 18. A light emitting device having a structure according to the present invention is provided on the substrate 10.

In the light-emitting device having the structure as described above, the light-emitting element 12 is a light-emitting element according to the present invention, and in particular, the light-emitting layer 15 includes the above-mentioned layer including a metal oxide as a component.

The transistor 11 is included in the top gate type. However, the structure of transistor 11 is not particularly limited. For example, an inverted staggered TFT as shown in FIG. 10A can be used. In the case of an inverted staggered TFT, a TFT (channel-protection TFT) in which a protective film is formed on a semiconductor layer forming a channel can be used, as shown in FIG. 10B, or a TFT in which a part of the semiconductor layer forming a channel is recessed TFT (channel-etch TFT). Here, reference numerals 21, 22, 23, 24, 25, and 26 denote gate electrodes, gate insulating films, semiconductor layers, n-type semiconductor layers, electrodes, and protective films, respectively.

In addition, the semiconductor layer forming the transistor 11 may be crystalline or amorphous, or alternatively may be semi-amorphous.

The semi-amorphous semiconductor will be explained below. A semi-amorphous semiconductor is a semiconductor having an intermediate structure between amorphous and crystalline (such as single crystal or polycrystalline) structures, and has a third state stable in terms of free energy, which includes short-range order and crystal lattice Strained crystalline region. Also, crystal grains from 0.5 to 20 nm are included in at least one region in the semi-amorphous semiconductor film. The Raman spectrum of a semi-amorphous semiconductor has a ratio of 520 cm^-1Drift on the lower wavenumber side. In X-ray diffraction, diffraction peaks of (111) and (220) due to the Si lattice are observed. The semi-amorphous semiconductor includes 1 atomic% or more of hydrogen or halogen to terminate the dangling bond. Therefore, semi-amorphous semiconductors are also called microcrystalline semiconductors. The nitride gas is decomposed by glow discharge (plasma CVD) to form a semi-amorphous semiconductor. As a nitride gas, except for SiH₄In addition, you can also use, for example, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄Or SiF₄gas. Can use H₂Or H₂And one or more rare gas elements selected from He, Ar, Kr and Ne to dilute the nitride gas, wherein the dilution ratio is in the range of 2:1 to 1000:1. During the glow discharge, the pressure is approximately in the range of 0.1 Pa to 133 Pa, and the power supply frequency is in the range of 1 MHz to 120 MHz, preferably 13 MHz to 60 MHz. The substrate heating temperature may be 300°C or less, preferably 100°C to 250°C. It is desirable to control the composition of atmospheric impurities such as oxygen, nitrogen or carbon so as to have 1×10²⁰/cm³Or less, as an impurity element in the film, in particular, the oxygen concentration is controlled to 5×10¹⁹/cm³Or smaller, preferably 1×10¹⁹/cm³Or smaller. In addition, a TFT (thin film transistor) using a semi-amorphous semiconductor has about 1 to 10 m²/Vsec mobility.

Also, crystalline semiconductors used in specific examples of the semiconductor layer include single crystal or polycrystalline silicon and silicon-germanium, which may be formed by laser crystallization, or may be formed by crystallization with solid phase growth using an element such as nickel.

In the case of using an amorphous material, such as amorphous silicon, to form the semiconductor layer, it is preferable that the light-emitting device has an n-channel circuit in which the transistor 11 and other transistors (transistors forming circuits for driving the light-emitting elements) are used. Crystal circuit. Except for this case, the light-emitting device may have a circuit including one of an n-channel transistor and a p-channel transistor, or may have a circuit including both an n-channel transistor and a p-channel transistor.

Also, the first interlayer insulating films 16a to 16c may be multiple layers as shown in FIGS. 9A and 9C, or may be a single layer. The first interlayer insulating film 16a includes an inorganic material such as silicon oxide or silicon nitride, and the first interlayer insulating film 16b includes a material with automatic flattening that can be used for deposition in coating, such as acrylic, silicone (with A framework structure formed by the bond between silicon (Si) and oxygen (O) and includes at least hydrogen as a substituent material) and silicon oxide. In addition, the first interlayer insulating film 16c has a silicon nitride film including argon (Ar). The materials included in each layer are not particularly limited, and therefore materials other than the materials mentioned here may be used. Also, layers including materials other than these materials may be combined. In this way, the first interlayer insulating film 16 can be formed using both an inorganic material and an organic material, or one of an inorganic material and an organic material.

As for the separation layer 18, it is preferable that the boundary portion has a shape in which the radius of curvature continuously changes. In addition, the separation layer 18 is formed using a material such as acrylic, siloxane, resist, or silicon oxide. One or both of inorganic materials and organic materials may be used to form the separation layer 18.

In each of FIGS. 9A and 9C, only the first interlayer insulating film 16 is provided between the transistor 11 and the light emitting element 12. However, as shown in FIG. 9B, in addition to the first interlayer insulating film 16 (16a and 16b), a second interlayer insulating film 19 (19a and 19b) may be provided. In the light-emitting device shown in FIG. 9B, the first electrode 13 is connected to the wiring 17 through the second interlayer insulating film 19.

The second interlayer insulating film 19 may be a multilayer or a single layer in the same manner as the first interlayer insulating film 16. The second interlayer insulating film 19a includes a material with automatic flatness that can be used for deposition in coating, such as acrylic, siloxane (with a frame structure formed by the bond between silicon (Si) and oxygen (O) And at least include hydrogen as a substituent material) and silicon oxide. In addition, the second interlayer insulating film 19b has a silicon nitride film including argon (Ar). The materials included in each layer are not particularly limited, and therefore materials other than the materials mentioned here may be used. Also, layers including materials other than these materials may be combined. In this way, the second interlayer insulating film 19 can be formed using both an inorganic material and an organic material, or one of an inorganic material and an organic material.

In the light-emitting element 12, in the case where the first electrode 13 and the second electrode 14 are formed to include a light-emitting material, it can be extracted from the first electrode 13 side and the second electrode 14 side as indicated by the outline arrow of FIG. 9A. Emitted light. In the case where only the second electrode 14 is formed to include the luminescent material, the emitted light may be extracted only from the second electrode 14 side as indicated by the outline arrow of FIG. 9B. In this case, it is preferable that the first electrode 13 includes a highly reflective material, or a film (reflection film) including a highly reflective material is provided under the first electrode 13. In the case where only the first electrode 13 is formed to include the luminescent material, as indicated by the outline arrow of FIG. 9C, the emitted light may be extracted only from the first electrode 13 side. In this case, it is preferable that the second electrode 14 includes a highly reflective material or a reflective film is provided on the second electrode 14.

In addition, in the case of the light-emitting element 12, the first electrode 13 serves as an anode and the second electrode 14 serves as a cathode, or alternatively, the first electrode 13 serves as a cathode and the second electrode 14 serves as an anode. However, in the former case, the transistor 11 is a p-channel transistor, and in the latter case, the transistor 11 is an n-channel transistor.

The light-emitting device of this embodiment has a plurality of light-emitting elements (however, they are not shown in the figure). In the case where the emission wavelength of each light-emitting element is the same as the emission wavelength of the light-emitting element 12, the light-emitting device emits monochromatic light. When the emission wavelength of each light-emitting element is different, the light-emitting device can emit light of multiple colors, such as red (R), green (G), and blue (B) colors.

In the case of the above-mentioned light-emitting device, the light-emitting or non-light-emitting state is controlled by a transistor electrically connected to each light-emitting element. By controlling the light-emitting or non-light-emitting state of each light-emitting element, image display and the like can be performed. In light-emitting devices, by applying the present invention, defects caused by factors such as sputtering or short circuits between electrodes, which may be caused by the manufacturing technology of light-emitting elements, can be suppressed, and satisfactory images can be displayed .

[Example 4]

In this embodiment, referring to the top views of FIGS. 11 and 12 and the circuit diagrams of FIGS. 13A and 13B, the light emitting device according to the present invention will be explained.

Fig. 11 shows a top view of a pixel portion of a light emitting device with a display function. In the pixel part, a light-emitting element, a driving transistor 7001 that determines the light-emitting or non-light-emitting state of the light-emitting element according to the image signal, a switching transistor 7002 that controls the input of the image signal, and the light-emitting element are controlled to be non-luminous regardless of the image signal The erasing transistor 7003, the source signal line 7004, the first scan line 7005, the second scan line 7006, and the current supply line 7007 are in the state. In the region 7008, a light-emitting element according to the present invention is formed. In addition, FIG. 13A shows a driver circuit diagram of the pixel portion of the light-emitting element having the pixel structure shown in FIG. 11.

When the first scan line 7005 is selected in the writing period, the switching transistor 7002 having the gate connected to the first scan line 7005 is turned on. Then, when the video signal input to the source signal line 7004 is input to the gate of the driving transistor 7001 via the switching transistor 7002, current flows from the current supply line 7007 to the light emitting element to emit light. In the sustain period, the switching transistor 7002 is turned off by controlling the potential of the first scan line 7005 to maintain the potential of the video signal written in the writing period. During the erasing period, since the second scan line 7006 is selected to turn on the erasing transistor 7003, and thus the driving transistor 7001 is turned off, a state in which no current is supplied to the light-emitting element is forcibly generated.

FIG. 12 shows a top view of a pixel portion of a light emitting device with a display function, which has a circuit structure different from that of FIG. 11. In the pixel part, a drive transistor 7101 with a fixed gate potential is provided, a switching transistor 7102 that controls the input of the image signal, and an erasing transistor 7103 that controls the light-emitting element to be in a non-luminous state regardless of the image signal, and controls are provided for The current control transistor 7104 of the current of the light-emitting element, the source signal line 7105, the first scan line 7106, the second scan line 7107, the current supply line 7108, and the power supply line 7109. In the region 7110, a light-emitting element according to the present invention is formed. In addition, FIG. 13B shows a driver circuit diagram of the pixel portion of the light-emitting element having the pixel structure shown in FIG. 12.

When the first scan line 7106 is selected in the writing period, the switching transistor 7102 having the gate connected to the first scan line 7106 is turned on. Then, when the video signal input to the source signal line 7105 is input to the gate of the current control transistor 7104 through the switching transistor 7102, current flows from the current supply line 7108 through the driving transistor 7101 to the light emitting element to emit light. The driving transistor 7101 has a gate electrode connected to the power supply line 7109. In the sustain period, the switching transistor 7102 is turned off by controlling the potential of the first scan line 7106 to maintain the potential of the video signal written in the writing period. During the erasing period, since the second scan line 7107 is selected to turn on the erasing transistor 7103, thereby turning off the current control transistor 7104, a state in which no current is supplied to the light-emitting element is forced to occur.

In the above-mentioned light-emitting device, the structure of each transistor is not particularly limited. Either a single-gate structure or a multi-gate structure can be used. In addition, an LDD structure may be used, or a gate overlap LDD structure in which the LDD part overlaps the gate electrode may be used.

In the light-emitting device shown in this embodiment, by applying the present invention, defects caused by factors such as sputtering or short circuits between electrodes are suppressed, so that satisfactory images can be displayed.

[Example 5]

After the external input terminal was attached and sealed, the light-emitting devices according to the present invention in Examples 3 and 4 were installed in various electronic devices.

In these electronic devices according to the present invention, display defects (damage to the light emitting element) caused by defects of the light emitting element are suppressed, and satisfactory images can be displayed.

In this embodiment, referring to FIGS. 14, 15 and 16, a light-emitting device according to the present invention and an electronic device mounted with the light-emitting device will be explained. However, the light-emitting device and the electronic device shown in FIGS. 14, 15 and 16 are only an example, and it is not considered that the structure of the light-emitting device is limited to this embodiment.

Fig. 14 is a cross-sectional view of the light-emitting device after sealing. The substrate 6500 and the sealing substrate 6501 are bonded with a sealant 6502, thereby sandwiching the transistor and the light-emitting element according to the present invention. An FPC (Flexible Printed Circuit) 6503 serving as an external input terminal is attached to the edge of the substrate 6500. In addition, the area sandwiched between the substrate 6500 and the sealing substrate 6501 is filled with an inert gas such as nitrogen or a resin material.

Fig. 15 is a top view showing the frame form of the light emitting device according to the present invention. In FIG. 15, portions 6510, 6511, and 6512 shown by broken lines are a driver circuit portion (source-side driver circuit), a pixel portion, and a driver circuit portion (gate-side driver circuit). In the pixel portion 6511, a light-emitting element according to the present invention is provided. The driver circuit portions 6510 and 6512 are connected by an FPC 6503 and a set of wiring formed on the substrate 6500, which FPC 6503 serves as an external input terminal. By receiving signals from FPC (flexible printed circuit) 6503, such as video signals, clock signals, start signals, and reset signals, these signals are input to the source-side driver circuit 6510 or the gate-side driver circuit 6512. Also, a printed wiring board (PWB) 6513 is attached to the FPC 6503. In the driver section 6510, a shift register 6515, a switch 6516, and memories (latches) 6517 and 6518 are provided. In the driver circuit section 6512, a shift register 6519 and a buffer 6520 are provided. In addition to these, other functions can also be provided.

Fig. 16 shows an example of an electronic device equipped with a light emitting device according to the present invention.

FIG. 16 shows a laptop personal computer manufactured according to the present invention, which includes a main body 5521, a frame main body 5522, a display portion 5523, and a keyboard 5524. The display device is completed by incorporating the light-emitting device having the light-emitting element according to the present invention into a personal computer.

In this embodiment, a laptop personal computer is explained. However, it is also possible to install the light-emitting device having the light-emitting element according to the present invention to a device such as a mobile phone, a television, a car navigation system, or a lighting device.

Although the present invention has been fully explained by way of examples with reference to the accompanying drawings, it should be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications deviate from the scope of patent application of the present invention defined below, they should be understood as being included therein.

<p>200. . . Base</p><p>210. . . Light-emitting element</p><p>201. . . First electrode</p><p>202. . . level one</p><p>203. . . Second floor</p><p>204. . . the third floor</p><p>205. . . Fourth floor</p><p>206. . . Fifth floor</p><p>207. . . Second electrode</p><p>300. . . Base</p><p>301. . . First electrode</p><p>302. . . level one</p><p>303. . . Second floor</p><p>304. . . the third floor</p><p>305. . . Fourth floor</p><p>306. . . Fifth floor</p><p>307. . . Second electrode</p><p>11. . . Transistor</p><p>12. . . Light-emitting element</p><p>13. . . First electrode</p><p>14. . . Second electrode</p><p>15. . . Light-emitting element</p><p>16a-16c. . . First interlayer insulating film</p><p>17. . . wiring</p><p>18. . . Separate layer</p><p>10. . . Base</p><p>twenty one. . . Gate electrode</p><p>twenty two. . . Gate insulating film</p><p>twenty three. . . Semiconductor layer</p><p>twenty four. . . n-type semiconductor layer</p><p>25. . . electrode</p><p>26. . . Protective film</p><p>19a, 19b. . . Second interlayer insulating film</p><p>7001. . . Drive transistor</p><p>7002. . . Switching transistor</p><p>7003. . . Erase transistor</p><p>7004. . . Source signal line</p><p>7005. . . First scan line</p><p>7006. . . Second scan line</p><p>7007. . . Current supply line</p><p>7008. . . area</p><p>7101. . . Drive transistor</p><p>7102. . . Switching transistor</p><p>7103. . . Erase transistor</p><p>7104. . . Current control transistor</p><p>7105. . . Source signal line</p><p>7106. . . First scan line</p><p>7107. . . Second scan line</p><p>7108. . . Current supply line</p><p>7109. . . power cable</p><p>7110. . . area</p><p>6500. . . Base</p><p>6501. . . Seal the base</p><p>6502. . . Sealants</p><p>6503. . . Flexible printed circuit</p><p>6511. . . Pixel part</p><p>6510. . . Source side driver circuit</p><p>6512. . . Gate side driver circuit</p><p>6513. . . Printed circuit board</p><p>6515. . . Shift register</p><p>6516. . . switch</p><p>6517. . . Memory (latch)</p><p>6518. . . Memory (latch)</p><p>6520. . . buffer</p><p>6519. . . Shift register</p><p>5521. . . main body</p><p>5522. . . Frame body</p><p>5523. . . Display part</p><p>5524. . . keyboard</p>

In the attached picture:

Fig. 1 shows a voltage-luminance characteristic diagram of a light-emitting element according to the present invention and a light-emitting element according to a comparative example;

2A to 2C are diagrams illustrating a multilayer structure of a light-emitting element according to the present invention;

3 is a diagram illustrating a multilayer structure of a light-emitting element according to the present invention;

Fig. 4 shows a voltage-current characteristic diagram of a light-emitting element according to the present invention and a light-emitting element according to a comparative example;

Fig. 5 shows a luminance-current efficiency characteristic diagram of the light-emitting element according to the present invention;

Fig. 6 shows a voltage-luminance efficiency characteristic diagram of the light-emitting element according to the present invention;

Fig. 7 shows a voltage-current characteristic diagram of the light-emitting element according to the present invention;

Fig. 8 shows a luminance-current efficiency characteristic diagram of a light-emitting element according to the present invention;

9A-9C are diagrams illustrating the cross-sectional structure of the light-emitting device according to the present invention;

10A and 10B are diagrams illustrating a cross-sectional structure of a light emitting device according to the present invention;

Figure 11 is a top view of the pixel portion of the light emitting device according to the present invention;

Figure 12 is a top view of the pixel portion of the light-emitting device according to the present invention;

13A and 13B are circuit diagrams of the pixel portion of the light-emitting device according to the present invention;

14 is a cross-sectional structure diagram illustrating a light-emitting device according to the present invention;

Figure 15 shows a view of the frame form of the light emitting device according to the present invention; and

Fig. 16 is a diagram of an electronic device equipped with a light emitting device according to the present invention.