JP4906033B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting element typified by an organic EL element and a display device having the light emitting element.

In recent years, a display device having a light emitting element typified by an organic EL (Electro Luminescence) element has been developed, and it is widely used by taking advantage of self-light emitting type, such as high image quality, wide viewing angle, thinness, and light weight. Expected. An EL element is a light emitting element based on the principle that an electroluminescent layer sandwiched between both electrodes emits light by a current flowing between a cathode and an anode. As the light emitting element, for example, a so-called top emission type light emitting element is known in which the electrode on the counter substrate side is transparent and the light from the light emitting layer is emitted to the counter substrate side. The cross-sectional structure is shown in FIG. In FIG. 17, 1 is a substrate, 2 is an electrode, 3 is a hole transport layer, 4 is a light emitting layer, 5 is an electron injection layer, 6 is a transparent electrode, 7 is a moisture-proof layer, and 8 is an antireflection layer. . This light emitting device was generated by recombination of electrons injected from the transparent electrode 6 through the electron injection layer 5 into the light emitting layer 4 and holes injected from the electrode 2 through the hole transport layer 3 into the light emitting layer 4. An element that uses light emitted when an exciton returns to a ground state.

In a light emitting element that extracts light from the upper surface side (opposite substrate side) such as the top emission type light emitting element, it is necessary to use the transparent electrode 6 as the counter electrode. For example, indium tin oxide (ITO) is used. It is used. In this case, since the difference in refractive index between the transparent electrode 6 and the air existing therearound is large, there is a problem that the light extraction efficiency is reduced (see Patent Documents 1 and 2).

In particular, light-emitting elements mainly composed of organic compounds are likely to be deteriorated mainly due to moisture and oxygen. As a defective state due to this cause, a partial decrease in luminance or a non-light-emitting region may occur. There are things to do. In order to prevent this, a technique for forming a passivation film (moisture-proof layer 7) such as a moisture-resistant SiN film on the transparent electrode 6 is known (see Patent Document 2). However, even when a passivation film (moisture-proof layer 7) such as a moisture-resistant SiN film is formed on the transparent electrode 6, since the difference in refractive index between the SiN film and air is large, the light extraction efficiency is high. There has been a problem of reduction (see Patent Document 2).

To solve these problems, a technique is known in which a material having a refractive index lower than that of the transparent electrode 6 is formed as a single layer or a multilayer on the transparent electrode 6 or the moisture-proof layer 7 as the antireflection layer 8 (patent). References 1 and 2).
JP 2003-303679 A Japanese Patent Laid-Open No. 2003-303585

However, the refractive index of the transparent electrode 6 is, for example, about 1.9 to 2.0 in the case of ITO, whereas the refractive index of the moisture-proof layer 7 provided on the transparent electrode 6 is about 2. It is about 1 to 2.3, which is higher than the refractive index of the transparent electrode 6. Therefore, when the moisture-proof layer 7 such as a SiN film is provided on the transparent electrode 6, even if the antireflection layer 8 having a lower refractive index than that of the transparent electrode 6 is provided on the moisture-proof layer 7, The difference in refractive index from the antireflection layer 8 remained large. Therefore, the reflectance at the interface between the moisture-proof layer 7 and the anti-reflection layer 8 is higher than that when the moisture-proof layer 7 is not provided, that is, the light reflection loss at the interface is further increased, so that the light-emitting layer There is a problem that the efficiency of extracting light from the outside becomes low.

Further, when the moisture-proof layer 7 is provided, film peeling (cracking) or cracking (crack) due to stress is likely to occur, and the yield of light-emitting elements is reduced, and the reliability and life of the manufactured light-emitting elements are reduced. There was a problem that it would bring about a decline.

An object of the present invention is to solve at least one of the above problems. That is, even when a passivation film is provided on a transparent electrode, an object is to provide a light-emitting element that is less likely to cause peeling or cracking and has high reliability and a display device using the light-emitting element. Alternatively, it is an object to provide a light emitting element having high efficiency of extracting light from the light emitting layer and a display device using the light emitting element. Alternatively, it is an object of the present invention to provide a light emitting element that can solve all of the above problems at the same time and a display device using the light emitting element.

The light emitting device according to the present invention is characterized in that a pixel electrode, an electroluminescent layer, a transparent electrode, a passivation film, a stress relaxation layer, and a low refractive index layer are sequentially laminated. Here, the stress relaxation layer has a function of preventing the passivation film from peeling off. The low refractive index layer has a function of reducing the reflectance when light emitted from the electroluminescent layer enters the air and improving the light extraction efficiency. The pixel electrode and the transparent electrode function as an anode or a cathode for supplying electrons or holes to the electroluminescent layer. The passivation film has a function of preventing impurities such as moisture from entering the transparent electrode and the electroluminescent layer. The passivation film, the stress relaxation layer, or the low refractive index layer may have a laminated structure. The stress relaxation layer may also be provided between the transparent electrode and the passivation film. The electroluminescent layer may have a single layer structure or a laminated structure.

The light emitting device according to the present invention includes a pixel electrode, an electroluminescent layer, a transparent electrode, a passivation film, a stress relaxation layer, and a low refractive index layer, which are sequentially stacked, and the refractive index of the low refractive index layer is the stress It is characterized by being smaller than the refractive index of the relaxation layer. The low refractive index layer has a function of reducing a difference in refractive index between the stress relaxation layer and a space (a space filled with a filling gas such as air or nitrogen; the same applies hereinafter).

The light-emitting element according to the present invention is characterized in that a pixel electrode, an electroluminescent layer, a transparent electrode, a stress relaxation layer, a passivation film, and a low refractive index layer are sequentially laminated.

The light emitting device according to the present invention is characterized in that a pixel electrode, an electroluminescent layer, a transparent electrode, a first stress relaxation layer, a passivation film, a second stress relaxation layer, and a low refractive index layer are sequentially laminated. And Here, the refractive index of the low refractive index layer may be smaller than the refractive index of the second stress relaxation layer.

The display device according to the present invention includes a transistor provided over a substrate and a light-emitting element connected to the transistor through an interlayer insulating film. The light-emitting element includes a pixel electrode, an electroluminescent layer, A transparent electrode, a passivation film, a stress relaxation layer, and a low refractive index layer are laminated. Here, the transistor has a function of controlling lighting and non-lighting of the light-emitting element, but a transistor having another function may be included. This transistor is usually a thin film transistor (TFT), but is not limited thereto. The interlayer insulating film is an insulating film that separates the transistor and the light-emitting element, and may be a single layer or a stacked layer. The stress relaxation layer has a function of preventing the passivation film from peeling off. The low refractive index layer has a function of reducing the reflectance when light emitted from the electroluminescent layer enters the air and improving the light extraction efficiency. Desirably less than the rate. The pixel electrode and the transparent electrode function as an anode or a cathode for supplying electrons or holes to the electroluminescent layer. The passivation film has a function of preventing impurities such as moisture from entering the transparent electrode and the electroluminescent layer. The passivation film, the stress relaxation layer, or the low refractive index layer may have a laminated structure.

The display device according to the present invention includes a transistor provided over a substrate and a light-emitting element connected to the transistor through an interlayer insulating film. The light-emitting element includes a pixel electrode, an electroluminescent layer, A transparent electrode, a stress relaxation layer, a passivation film, and a low refractive index layer are sequentially laminated.

The display device according to the present invention includes a transistor provided over a substrate and a light-emitting element connected to the transistor through an interlayer insulating film. The light-emitting element includes a pixel electrode, an electroluminescent layer, A transparent electrode, a first stress relaxation layer, a passivation film, a second stress relaxation layer, and a low refractive index layer are sequentially laminated. Here, the refractive index of the low refractive index layer may be smaller than the refractive index of the second stress relaxation layer.

In the display device according to the present invention, the light emitting element may be sealed with a counter substrate through a filling layer. Here, it is desirable that the refractive index of the filling layer has a value substantially equal to the refractive index of the low refractive index layer or the counter substrate, or an intermediate value between the low refractive index layer and the counter substrate, but at least air Any liquid layer or solid layer larger than the refractive index of (or a filling gas such as nitrogen) may be used.

In the light emitting device according to the present invention, since the stress relaxation layer is formed in contact with the upper surface or the lower surface of the passivation film, the thickness of the passivation film is increased without being adversely affected by peeling or cracking of the passivation film. As a result, an extremely high blocking effect can be obtained. Therefore, a light-emitting element with high reliability and long life can be provided with high yield.

In addition, when a stress relaxation layer is provided on the upper surface of the passivation film (including the case where the stress relaxation layer is provided on both sides), the stress relaxation is achieved by making the refractive index of the low refractive index layer smaller than the refractive index of the stress relaxation layer. The difference in refractive index between the layer and the space can be reduced, and the light extraction efficiency to the external space can be improved.

The display device according to the present invention has a stress relaxation layer on the passivation film in the light-emitting element, thereby increasing the thickness of the passivation film without being adversely affected by peeling or cracking of the passivation film. As a result, an extremely high blocking effect can be obtained. Accordingly, a highly reliable display device can be provided with high yield.

In addition, when the refractive index of the low refractive index layer is made smaller than the refractive index of the stress relaxation layer, the difference in refractive index between the stress relaxation layer and the space can be reduced, and the light to the external space can be reduced. The extraction efficiency can be improved. Further, when a filling layer is provided between the low refractive index layer and the counter substrate, the light extraction efficiency to the external space can be further improved.

Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments and examples below. For example, it is possible to carry out by combining the following embodiments and characteristic portions of the examples. Note that in the structures of the present invention described below, the same reference numerals are used in common in different drawings.

Note that in this specification, a light-emitting element is generally referred to as (1) an element including an anode, a cathode, and an electroluminescent layer (also referred to as an organic compound layer or EL layer) provided therebetween. In addition to the definition, the definition includes (2) an element in which a passivation film, a stress relaxation layer, a low refractive index layer and the like, which are characteristic parts of the present invention, are formed on the anode or the cathode. In other words, a light emitting element may be included including a portion that exhibits a function peculiar to the present invention of reducing a difference in refractive index in a light transmitting portion or relieving stress of a passivation film. In the present specification, when various compound materials are described using chemical formulas, materials having an arbitrary composition ratio can be appropriately selected unless otherwise indicated (for example, “SiN”). In this case, it means SixNy (x, y> 0).) The refractive index may be abbreviated as n.

Embodiment Mode 1 A structure of a light-emitting element according to this embodiment mode will be described with reference to FIG. FIG. 1A is a schematic cross-sectional view of the light-emitting element according to this embodiment. As shown in FIG. 1A, the light emitting device according to the present invention includes a pixel electrode 11, an electroluminescent layer 12, a transparent electrode 13, a passivation film 14, a stress relaxation layer 15, and a low refractive index layer 16, and It is provided on the substrate 10. The light-emitting element according to the present invention is a light-emitting element capable of so-called top emission (upper surface light emission), and is provided on the passivation film 14 provided on the transparent electrode 13 serving as a light emission extraction electrode, and on the passivation film 14. And a low refractive index layer 16 provided on the stress relaxation layer 15. The present invention can be applied to both a top emission type light emitting device and a dual emission type (light emitting on both sides) type that takes out light from both upper and lower sides of a light emitting layer. In FIG. 1A, for the sake of convenience, only top emission light is shown. This will be specifically described below.

The substrate 10 is a substrate having an insulating surface made of glass, quartz, plastic, or the like, but is not limited thereto. In addition, when using a plastic substrate, if it has flexibility, it will not specifically limit, For example, a polyethylene terephthalate (PET), a polyether sulfone (PES), a polyethylene naphthalate (PEN), a polycarbonate (PC), nylon A plastic substrate made of one selected from polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyarylate (PAR), polybutylene terephthalate (PBT), and polyimide can be used. .

A pixel electrode 11 is provided on the substrate 10. In the case of the top emission type, a reflective metal material is used as the pixel electrode 11 regardless of whether the pixel electrode 11 functions as an anode or a cathode. For example, in the case of a cathode, a light-transmitting conductive film formed by co-evaporation with Al, AlLi, MgAg, MgIn, Ca, or an element belonging to Group 1 or 2 of the periodic table and aluminum can be used. . Since these materials have a small work function and easily extract electrons, they are suitable as a cathode material. In this case, the structure of the light emitting element is formed by laminating an electroluminescent layer and an anode in this order on the cathode from the substrate side. This laminated structure is called reverse stacking structure.

On the other hand, when the pixel electrode 11 functions as an anode, an element selected from Cr, Ti, TiN, TiSixNy, Ni, W, WSix, WNx, WSixNy, NbN, Pt, Zn, Sn, In, or Mo, or A film mainly containing an alloy material or compound material containing the element as a main component or a stacked film thereof may be used. In this case, the structure of the light emitting element is formed by laminating the electroluminescent layer and the cathode in this order on the anode from the substrate side. This laminated structure is called a sequential stacking structure.

On the other hand, in the case of the dual emission type, since it is necessary to perform bottom emission, a metal material having optical transparency is used as the pixel electrode 11. Typically, ITO is used. ITO is generally used as the anode. In this case, the structure of the light emitting element is a stacked structure. When the pixel electrode 11 functions as a cathode, a thin film such as Li as a cathode material may be formed between the ITO and the electroluminescent layer 12 while ensuring transparency using ITO. Instead of ITO, ITSO containing silicon oxide in ITO, zinc oxide (ZnO: Zinc Oxide), zinc oxide added with gallium (GZO), and zinc oxide of about 1 to 20% were mixed with indium oxide. A transparent conductive film such as indium zinc oxide (IZO) can also be used.

Note that a barrier layer containing silicon, silicon oxide, silicon nitride, or the like may be sandwiched between the transparent conductive film such as ITO and the electroluminescent layer 12. This has been experimentally found to increase luminous efficiency. Further, the pixel electrode 11 may be an electrode having an antireflection function in which the upper and lower surfaces of ITO or the like are covered with a Cr film or the like. Thereby, it is possible to prevent external light or emitted light from being reflected by the pixel electrode 11 and interfering with light extracted outside.

An electroluminescent layer 12 is provided on the pixel electrode 11. In the case of stacking, the electroluminescent layer 12 may have a stacked structure of a hole transport layer 3, a light emitting layer 4, and an electron injection layer 5 as shown in the conventional example (see FIG. 17), or only the light emitting layer. A single layer structure may be used. When composed of a plurality of layers, as viewed from the substrate 1 side, (1) a hole (hole) injection layer, hole transport layer, light emitting layer, electron transport layer, cathode on the anode, (2) on the anode Hole injection layer, light emitting layer, electron transport layer, cathode, (3) hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer, cathode on the anode, (4) hole injection on the anode Layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, cathode, (5) hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, cathode on the anode It is also possible to form an element structure in which the layers are stacked in this order. Since the above is the case of order stacking, in the case of reverse stacking, the stacking order may be reversed.

The electroluminescent layer 12, which can be said to be the center of the light emitting element, is generally composed of an organic compound layer, and the above-described hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer and the like are all included in the electroluminescent layer 12. . As the layer constituting the electroluminescent layer 12, a low molecular organic compound material, a medium molecular organic compound material, a high molecular (polymer) organic compound material or an inorganic material, or a material appropriately combining these materials may be used. Although it is possible, in general, a polymer material is easier to handle and has higher heat resistance than a low-molecular material. Alternatively, a mixed layer in which an electron transporting material and a hole transporting material are appropriately mixed, or a mixed junction in which a mixed region is formed at each joint interface may be formed. Further, a fluorescent pigment or the like may be doped into the light emitting layer. As a method for forming these organic compounds, methods such as a vapor deposition method, a spin coating method, and an ink jet method are known. In particular, in order to realize full color using a polymer material, a spin coating method and an ink jet method are suitable.

In order to improve reliability, it is preferable to perform deaeration by performing vacuum heating (100 ° C. to 250 ° C.) immediately before the formation of the electroluminescent layer 12. For example, when the vapor deposition method is used, the degree of vacuum is 0.665 Pa (5 × 10 ⁻³ Torr) or less, preferably 1.33 × 10 ⁻² Pa to 1.33 × 10 ⁻⁴ Pa (10 ⁻⁴ to 10 ⁻ Evaporation is performed in a deposition chamber evacuated to ⁶ Torr). In the vapor deposition process, the organic compound is vaporized in advance by resistance heating, and when the shutter is opened, the organic compound is scattered in the direction of the substrate and vapor deposition is performed. The vaporized organic compound scatters upward and is deposited on the substrate through an opening provided in the metal mask. For example, Alq ₃ (hereinafter sometimes referred to as “Alq”), Alq ₃ partially doped with Nile Red, which is a red luminescent dye, p-EtTAZ, and TPD (aromatic diamine) are sequentially stacked by vapor deposition. Thus, white can be obtained.

Moreover, when forming the electroluminescent layer 12 by the apply | coating method using spin coating, after apply | coating, it is preferable to bake by vacuum heating. For example, a poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) aqueous solution (PEDOT / PSS) that acts as a hole injection layer is applied and baked on the entire surface, and then a luminescent center dye (1, 1,4,4-tetraphenyl-1,3-butadiene (TPB), 4-dicyanomethylene-2-methyl-6- (p-dimethylamino-styryl) -4H-pyran (DCM1), Nile Red, Coumarin 6 Etc.) A doped polyvinyl carbazole (PVK) solution may be applied to the entire surface and fired. PEDOT / PSS uses water as a solvent and does not dissolve in organic solvents. Therefore, when PVK is applied from above, there is no fear of redissolving. Further, since PEDOT / PSS and PVK have different solvents, it is preferable not to use the same film forming chamber. Further, the electroluminescent layer 12 may be a single layer, and an electron transporting 1,3,4-oxadiazole derivative (PBD) may be dispersed in hole transporting polyvinyl carbazole (PVK). Further, white light emission can be obtained by dispersing 30 wt% PBD as an electron transporting agent and dispersing an appropriate amount of four kinds of dyes (TPB, coumarin 6, DCM1, Nile red).

Although an example of a light-emitting element that emits white light is shown here, a light-emitting element that can obtain red light emission, green light emission, or blue light emission can be manufactured by appropriately selecting the material of the electroluminescent layer 12. Needless to say. In this case, a color filter as shown in FIG. 6 can be omitted. Further, the light emitting mechanism of the light emitting element is such that an electron injected from the cathode and a hole injected from the anode are at the emission center in the organic compound layer by applying a voltage with the organic compound layer sandwiched between a pair of electrodes. It is generally considered that a molecular exciton is formed by recombination and emits energy when the molecular exciton returns to the ground state. As excited states, singlet excitation and triplet excitation are known, and any of the light-emitting elements according to the present invention can be applied.

For example, when light emission from a triplet excited state (phosphorescence) is used, CBP + Ir (ppy) ₃ made of carbazole can be used as an organic compound (also referred to as a triplet compound) from which phosphorescence can be obtained. Phosphorescence has the advantage that it has higher luminous efficiency than light emission from a singlet excited state (fluorescence), and the operating voltage (voltage required for causing the organic light-emitting element to emit light) can be lowered to obtain the same light emission luminance. Have

Next, a transparent electrode 13 is provided on the electroluminescent layer 12. When the transparent electrode 13 functions as an anode, a transparent conductive film such as ITO may be used. On the other hand, when the transparent electrode 13 functions as a cathode, a thin film such as Li as a cathode material may be formed between the transparent electrode 13 and the electroluminescent layer 12.

A passivation film 14 is provided on the transparent electrode 13. The passivation film 14 includes silicon nitride (typically Si ₃ N ₄ ), silicon oxide (typically SiO ₂ ), silicon nitride oxide (SiNO (composition ratio N> O)), silicon oxynitride (SiON). (Composition ratio N <O) or a thin film (DLC (Diamond Like Carbon) film, CN film, etc.) containing carbon as a main component, etc., is preferably formed by a single layer or stacked layers, particularly a passivation made of nitride. Since the film 14 is dense, it protects the transparent electrode 13 and has a very high blocking effect against moisture, oxygen, and other impurities that adversely affect the electroluminescent layer 12.

As described above, the passivation film 14 has a high blocking effect. However, as the film thickness increases, the film stress increases and peeling and cracks (cracks) are likely to occur. However, by providing the stress relaxation layer 15 on the passivation film 14, peeling of the passivation film 14 can be prevented. As the stress relaxation layer 15, an organic material or an inorganic material having a low stress can be appropriately selected and used, but it is preferable to use a material having a lower refractive index than the transparent electrode 13 or the passivation film 14. For example, a polyimide resin, an acrylic resin, or a styrene resin can be used. In addition, polyamide, polyimide amide, resist or benzocyclobutene, and an SOG film obtained by a coating method (for example, siloxane has a skeleton structure formed of a bond of silicon (Si), oxygen, and (O). As a group, an organic group containing at least hydrogen (for example, an alkyl group or an aromatic hydrocarbon) is used, a fluoro group may be used as a substituent, or an organic group containing at least hydrogen as a substituent and a fluoro group An SiOx film containing an alkyl group using a coating film, a SiOx film using a polysilazane coating film), or the same or similar material as the organic material used for the electroluminescent layer can be used.

Thus, by providing the stress relaxation layer 15, the thickness of the passivation film 14 can be increased without being adversely affected by peeling or cracking of the passivation film 14, resulting in an extremely high blocking effect. be able to. Note that materials used as the stress relaxation layer include those having a function as a passivation film. Even in such a case, a function as a stress relaxation layer (that is, a function that can prevent peeling or cracking of the film as a result of being formed in contact with a material having a relatively large film stress, or actually As long as it has a function that realizes a state in which peeling or cracking of the film is prevented, it is included in the stress relaxation layer. For example, when SiN (refractive index n = 2.1 to 2.3) is formed as a passivation film, stress relaxation of SiO ₂ (n = 1.5) or SiNO (n = 1.8) is further performed. For example, it may be formed as a layer (and as a passivation film).

Next, the low refractive index layer 16 is provided on the stress relaxation layer 15. Here, the low refractive index layer 16 refers to a layer having a lower refractive index than the stress relaxation layer 15 and a higher refractive index than the atmosphere outside the light emitting element (usually n = 1). The external atmosphere may be air or may be filled with nitrogen gas or the like.

Here, when the stress relaxation layer 15 is provided on the passivation film 14, the refractive indexes of the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16 are n _T , n _P , n, respectively. _{Assuming B 1} and n _L , these relationships are preferably as follows.

(1) In the case of n _T <n _P , the relationship of n _P > n _B > n _L is satisfied.
₍₂₎ For _n T> n _P, satisfies the relationship of _{n T> n B> n L} . More preferably, the relationship of n _P > n _B > n _L or n _P ≈n _B > n _L is satisfied (that is, the relationship in which the refractive index gradually decreases from the transparent electrode 13 to the low refractive index layer 16). Fulfill.).

For example, when ITO is used as the transparent electrode 13, the refractive index is 1.9 to 2.0. Further, for example, when SiN is used as the passivation film 14, the refractive index is 2.1 to 2.3, and when SiNO is used, the refractive index is about 1, 8 and SiO ₂ is used. When used, the refractive index is about 1.5. Therefore, as described above, the refractive index of the material used as the stress relaxation layer 15 is polyimide resin (n = 1.50 to 1.55), acrylic resin (n = 1.45 to 1.50), styrene resin. (n = 1.55~1.60), magnesium fluoride _{(MgF 2, n = 1.38~1.40)} , barium fluoride _{(BaF 2, n = 1.47)} , used in the electroluminescent layer An organic material (n = 1.6) or the like may be used. Further, MgO (n = 1.64 to 1.74), SrO ₂ , and SrO are hygroscopic and translucent, and can be obtained as a thin film by a vapor deposition method. Therefore, they are suitable as the stress relaxation layer 15.

When an organic material is used as the stress relaxation layer 15, α-NPD (4,4′-bis- [N- (naphthyl) -N-phenyl-amino] biphenyl), BCP (bathocuproin), MTDATA (4 , 4 ′, 4 ″ -tris (N-3-methylphenyl-N-phenyl-amino) triphenylamine), Alq ₃ (tris-8-quinolinolato aluminum complex), and the like. The material is hygroscopic and is almost transparent when the film thickness is thin.

Further, as the low refractive index layer 16, lithium fluoride (LiF, n = 1.30 to 1.39), magnesium fluoride (MgF ₂ , n = 1.38 to lower in refractive index than the stress relaxation layer 15 is used. 1.40), calcium fluoride (CaF ₂ , n = 1.23 to 1.45), barium fluoride (BaF ₂ , n = 1.47), or the like may be used.

Note that the material of the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16 is not limited to those described above as long as either of the relations (1) and (2) is satisfied. . With respect to the refractive indexes of the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16, the difference in refractive index at the interface between the respective layers can be obtained by providing the relationship (1) or (2). Can be reduced, and the light extraction efficiency to the external space can be improved.

The transparent electrode 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16 can be formed using a sputtering method, a CVD method, a vapor deposition method, or the like. For example, the transparent electrode 13 may be formed by sputtering, the passivation film 14 may be formed by CVD, and the stress relaxation layer 15 and the low refractive index layer 16 may be formed by vapor deposition. In this case, by adopting a multi-chamber system that integrates a sputter film forming chamber, a CVD film forming chamber, a vapor deposition chamber, a baking chamber for performing a drying process, etc., a substrate is transferred to each chamber and film is formed efficiently. It can be performed.

As described above, the light-emitting element according to the present invention has the stress relaxation layer 15 on the passivation film 14, so that the thickness of the passivation film 14 is not adversely affected by peeling or cracking of the passivation film 14. As a result, an extremely high blocking effect can be obtained.

The stress relaxation layer 15 has an intermediate refractive index between the passivation film 14 or the transparent electrode 13 and the low refractive index layer 16, so that the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16. The difference in refractive index at the interface between the layers can be reduced, and the light extraction efficiency to the external space can be improved.

Note that the light-emitting element according to the present invention can be employed in a light-emitting device typified by an EL display. The light emitting device has a method of forming an electroluminescent layer between two types of stripe electrodes provided so as to be orthogonal to each other (simple matrix method) or a pixel electrode connected to a TFT and arranged in a matrix. The light emitting element according to the present invention can be applied to both a simple matrix method and an active matrix method, which are roughly classified into two types (active matrix method) in which an electroluminescent layer is formed between electrodes. it can.

Embodiment Mode 2 A structure of a light-emitting element according to this embodiment mode will be described with reference to FIG. FIG. 1B is a schematic cross-sectional view of the light-emitting element according to this embodiment. The invention according to the present embodiment is characterized in that the passivation film 14 has a laminated structure. The illustrated configuration has a three-layer structure in which a silicon oxide film 14b and a silicon nitride film 14c are stacked in this order on the silicon nitride film 14a. Here, the second SiO ₂ film has a function as a passivation film and a function for preventing peeling or cracking of the SiN film (function as a stress relaxation layer). And by setting it as a three-layer structure, the barrier function which a passivation film has can improve, and the penetration | invasion of the water | moisture content, oxygen, and another impurity to the transparent electrode 13 or the electroluminescent layer 12 can be prevented effectively.

Note that the structure of the passivation film 14 is not limited to that shown in FIG. 1B, but it is desirable to use a film having the smallest possible difference in the refractive index at the interface between the layers constituting the passivation film. Further, a stress relaxation layer 15 and a low refractive index layer 16 are provided on the passivation film 14. The stress relaxation layer 15 in the present embodiment only needs to satisfy the relationships (1) and (2) in the first embodiment with respect to the uppermost layer of the passivation film 14. Further, when the stress relaxation layer 15 itself has a laminated structure using the material shown in the first embodiment, the low refractive index layer 16 is the same as that in the first embodiment with respect to the uppermost layer of the stress relaxation layer 15. It is only necessary to satisfy the relationship of (1) and (2). Note that the remaining structure of the light-emitting element according to this embodiment is similar to that of Embodiment 1.

In the light emitting device according to the present invention, since the passivation film 14 has a laminated structure, the barrier function is improved, and the penetration of moisture, oxygen, and other impurities into the transparent electrode 13 and the electroluminescent layer 12 is more effectively prevented. be able to. Further, since the stress relaxation layer 15 is provided on the passivation film 14, the thickness of the passivation film 14 can be increased without being adversely affected by peeling or cracking of the passivation film 14. An extremely high blocking effect can be obtained.

In addition, the stress relaxation layer 15 has a refractive index intermediate between the passivation film 14 or the transparent electrode 13 and the low refractive index layer 16 in accordance with the relationship of (1) and (2) of the first embodiment. 13, the passivation film 14, the stress relaxation layer 15, and the low refractive index layer 16 can reduce the difference in refractive index at each interface, and can improve the light extraction efficiency to the external space.

Note that the light-emitting element according to the present invention can be employed in a light-emitting device typified by an EL display. The light emitting device has a method of forming an electroluminescent layer between two types of stripe electrodes provided so as to be orthogonal to each other (simple matrix method) or a pixel electrode connected to a TFT and arranged in a matrix. The light emitting element according to the present invention can be applied to both a simple matrix method and an active matrix method, which are roughly classified into two types (active matrix method) in which an electroluminescent layer is formed between electrodes. it can.

(Embodiment 3) With reference to FIG. 2, the structure of the light emitting element which concerns on this Embodiment is demonstrated. FIG. 2 is a schematic cross-sectional view of the light-emitting element according to this embodiment. The invention according to the present embodiment is characterized in that the space between the low refractive index layer 16 and the counter substrate 18 is filled with the filling layer 17. Here, the refractive index of the filling layer 17 may have a value substantially equal to the refractive index of the low refractive index layer 16 or the counter substrate 18, or an intermediate value between the low refractive index layer 16 and the counter substrate 18. desirable. For example, when the low refractive index layer 16 is LiF (n = 1.30 to 1.39) and the counter substrate 18 is a glass substrate (n = 1.5), the filling layer 17 has 1.2 to 1 It is better to use a material having a refractive index of about .6. For example, an inert liquid fluorinate (n = 1.23 to 1.31) containing fluorine may be used. Alternatively, a film of polytetrafluoroethylene (n = 1.36), polymethyl methacrylate (PMMA, n = 1.49), or a polymer containing fluorine (n = 1.35 to 1.43) may be used. Good.

However, the material is not limited to the above material as long as it has a value substantially equal to the refractive index of the low refractive index layer 16 or the counter substrate 18 or a value intermediate between them. Further, the lower limit of the refractive index may be about 1.2 or less because the effect of providing the filling layer 17 is exhibited as long as it is larger than air (n = 1).

The filling layer 17 can be formed by sealing a light emitting element with the counter substrate 18 and then injecting a liquid under vacuum. Alternatively, it can be manufactured using a droplet discharge method typified by an inkjet method, a dropping method, a printing method, a coating method, or the like.

Further, the counter substrate 18 is not limited to a glass substrate, and a quartz substrate, various plastic substrates shown in Embodiment Mode 1, or the like can be used. The same material as the substrate 10 may be used. Note that the remaining structure of the light-emitting element according to this embodiment is similar to that of Embodiment 1.

In the light emitting device according to the present invention, since the space between the low refractive index layer 16 and the counter substrate 18 is filled with the filling layer 17, the interface between the low refractive index layer 16 and the filling layer 17, the filling layer 17, and the like. The difference in refractive index between the interfaces of the counter substrate 18 can be reduced, and the light extraction efficiency can be further improved.

Note that the light-emitting element according to the present invention can be employed in a light-emitting device typified by an EL display. The light emitting device has a method of forming an electroluminescent layer between two types of stripe electrodes provided so as to be orthogonal to each other (simple matrix method) or a pixel electrode connected to a TFT and arranged in a matrix. The light emitting element according to the present invention can be applied to both a simple matrix method and an active matrix method, which are roughly classified into two types (active matrix method) in which an electroluminescent layer is formed between electrodes. it can.

Embodiment Mode 4 In this embodiment mode, a case where a stress relaxation layer is provided below a passivation film (pixel electrode side) will be described with reference to FIG. In the above-described embodiment, the stress relaxation layer is provided only on the passivation film, but the peeling of the passivation film 14 can also be achieved by forming the stress relaxation layer 15a below the passivation film 14 (FIG. 3A). Or a crack can be prevented effectively. By providing the stress relaxation layer 15a, the thickness of the passivation film 14 can be increased without being adversely affected by peeling or cracking of the passivation film 14, and as a result, an extremely high blocking effect can be obtained. it can. The stress relaxation layer 15a may have a laminated structure.

Here, as the stress relaxation layer 15a, an organic material or an inorganic material having a low stress can be appropriately selected and used. For example, SiNO is suitable as a stress relaxation layer. Further, SiO ₂ and SiON may be used. In addition, EL elements such as α-NPD (sometimes simply referred to as NPD), NPB (4,4′-bis- [N- (naphthyl) -N-phenyl-amino] biphenyl), TPD and so-called positive elements are used. Aromatic amines such as those classified as pore transport and injection materials can also be used. In the present embodiment, the refractive index of the stress relaxation layer 15a is not particularly limited, and a material can be selected.

Further, as shown in FIG. 3B, a stress relaxation layer 15a (first stress relaxation layer) and a stress relaxation layer 15b (second stress relaxation layer) may be provided above and below the passivation film. Here, the stress relaxation layer 15b may be used under the conditions described in the first embodiment. On the other hand, although there is no restriction | limiting in particular about the stress relaxation layer 15a, What is necessary is just to select and use the material mentioned above. The material of the stress relaxation layers 15a and 15b may be the same or different.

As described above, when the stress relaxation layers are provided above and below the passivation film 14, light extraction efficiency can be improved while preventing peeling and cracking of the passivation film 14.

In this example, the structure of an active matrix display device (also referred to as an active matrix light-emitting device; hereinafter the same) using the light-emitting elements according to Embodiments 1 to 3 is described with reference to FIGS. . In the display device according to this example, a plurality of source lines Sx (x is a natural number, 1 ≦ x ≦ m) and a plurality of gate lines Gy (y is a natural number, 1 ≦ y ≦ n) are intersected via an insulator. A plurality of pixels 310 including the above elements are included (FIG. 4A). The pixel 310 includes a light-emitting element 313, a capacitor 316, and two transistors. Of the two transistors, one is a switching transistor 311 that controls input of a video signal to the pixel 310, and the other is a driving transistor 312 that controls lighting and non-lighting of the light emitting element 313. The capacitor 316 has a function of holding the gate-source voltage of the transistor 312.

The gate electrode of the transistor 311 is connected to the gate line Gy, one of the source electrode and the drain electrode is connected to the source line Sx, and the other is connected to the gate electrode of the transistor 312. One of a source electrode and a drain electrode of the transistor 312 is connected to the first power supply 317 through a power supply line Vx (x is a natural number, 1 ≦ x ≦ l), and the other is connected to a pixel electrode of the light emitting element 313. The counter electrode (transparent electrode 13) of the light emitting element 313 is connected to the second power source 318. The capacitor 316 is provided between the gate electrode and the source electrode of the transistor 312. The conductivity types of the transistors 311 and 312 may be either N-type or P-type. However, in the illustrated structure, the transistor 311 is N-type and the transistor 312 is P-type. The potential of the first power source 317 and the potential of the second power source 318 are not particularly limited, but are set to different potentials so that a forward bias voltage or a reverse bias voltage is applied to the light emitting element 313.

A semiconductor included in the transistors 311 and 312 may be any of an amorphous semiconductor (amorphous silicon), a microcrystalline semiconductor, a crystalline semiconductor, an organic semiconductor, and the like. The microcrystalline semiconductor is formed by using silane gas (SiH ₄ ) and fluorine gas (F ₂ ), by using silane gas and hydrogen gas, or after forming a thin film by using the gas mentioned above, You may form by irradiating. The gate electrodes of the transistors 311 and 312 are formed as a single layer or stacked layers using a conductive material. For example, a stacked structure in which tungsten (W) is stacked on tungsten nitride (WN), a stacked structure in which aluminum (Al) and Mo are stacked on molybdenum (Mo), and Mo is sequentially stacked on molybdenum nitride (MoN). A laminated structure may be employed.

FIG. 4B is a top view of the display panel portion of the display device according to this example. 4B, a display region 400 including a plurality of pixels including light-emitting elements (the pixel 310 illustrated in FIG. 4A), a gate driver 401, a gate driver 402, a source driver 403, and an FPC over a substrate 405. A connection film 407 such as is provided (FIG. 4B). The connection film 407 is connected to an IC chip or the like.

FIG. 5 is a cross-sectional view taken along line AB of the display panel in FIG. FIG. 5A shows a top emission type display, and FIG. 5B shows a dual emission type display panel.

5A and 5B, the transistor 312 provided in the display region 400 (the transistor 311 in FIG. 4A is omitted), the light-emitting element 313, and the element group 410 provided in the source driver 403. Is shown. Reference numeral 316 denotes a capacitive element. A sealant 408 is provided around the display region 400, the gate drivers 401 and 402, and the source driver 403, and the light-emitting element 313 is sealed with the sealant 408 and the counter substrate 406. This sealing process is a process for protecting the light emitting element 313 from moisture. Here, a method of sealing with a cover material (glass, ceramics, plastic, metal, or the like) is used, but a thermosetting resin or ultraviolet light is used. A method of sealing with a curable resin or a method of sealing with a thin film having a high barrier ability such as a metal oxide or a nitride may be used. However, in order to improve the light extraction efficiency, it is desirable to use air or a material having a small refractive index with respect to the filling layer 17 in the third embodiment.

Here, as the sealant 408, typically, an ultraviolet curable or thermosetting epoxy resin may be used. Here, a highly heat-resistant UV epoxy resin having a refractive index of 1.50, a viscosity of 500 cps, a Shore D hardness of 90, a tensile strength of 3000 psi, a Tg point of 150 ° C., a volume resistance of 1 × 10 ¹⁵ Ω · cm, and a withstand voltage of 450 V / mil (electro Wright Corporation: 2500 Clear) is used.

In addition, the transparent electrode 13 in the light-emitting element 313 is connected to the second power source 318 in FIG. The element formed over the substrate 405 is preferably formed using a crystalline semiconductor (polysilicon) having favorable characteristics such as mobility as compared to an amorphous semiconductor. Realized. Since the number of external ICs to be connected is reduced, the panel having the above configuration can be made small, light, and thin.

Note that the display region 400 may be formed using a transistor using an amorphous semiconductor (amorphous silicon) formed over an insulating surface as a channel portion, and the gate drivers 401 and 402 and the source driver 403 may be formed using an IC chip. The IC chip may be bonded onto the substrate 405 by a COG method, or may be bonded to the connection film 407 connected to the substrate 405. An amorphous semiconductor can be easily formed on a large-area substrate by using the CVD method and does not require a crystallization step, so that an inexpensive panel can be provided. At this time, if a conductive layer is formed by a droplet discharge method typified by an ink jet method, a cheaper panel can be provided.

Here, FIG. 5A will be described in more detail. In the structure illustrated in FIG. 5A, a first interlayer insulating film 411, a second interlayer insulating film 412, and a third interlayer insulating film 413 are provided over the transistor 312 and the element group 410. A wiring 414 is formed through an opening provided in the first interlayer insulating film 411 and the second interlayer insulating film 412. The wiring 414 functions as a source wiring or a drain wiring of the transistor 312 and the element group 410, a capacitor wiring of the capacitor 316, or the like. As the wiring 414, an alloy containing aluminum and nickel is preferably used. Further, this alloy may further contain carbon, cobalt, iron, silicon or the like. These contents include, for example, 0.1 to 3.0 atomic% of carbon, 0.5 to 7.0 atomic% of at least one element among nickel, cobalt, and iron, and 0.5 to 2 of silicon. It is preferable to set it to 0 atomic%. One of the characteristics of this material is that the resistance value is as low as 3.0 to 5.0 Ωcm.

Here, when Al is used as the wiring 414, there is a problem that corrosion with the pixel electrode 11, for example, ITO occurs. However, even in such a case, good contact with ITO can be obtained by forming a laminated structure in which Al (or Al—Si alloy) is sandwiched between Ti or TiN. For example, a stacked structure in which Al and Ti are stacked in this order on Ti from the substrate side may be used. On the other hand, the Al—C alloy or Al—C—Ni alloy has an oxidation-reduction potential that is very close to that of a transparent conductive film such as ITO. Contact with ITO or the like is possible. The wiring 414 can be formed by a sputtering method using a target material made of the above alloy. Further, when etching the above alloy using a resist as a mask, it is preferable to perform the etching by wet etching. In this case, phosphoric acid or the like can be used as the etchant. Note that a wiring connected to the second power supply 318 can be formed in a manner similar to that of the wiring 414.

Further, the pixel electrode 11 is formed through an opening provided in the third interlayer insulating film 413. Since FIG. 5A is a top emission type, the pixel electrode 11 uses a reflective conductive film.

The material of the first to third interlayer insulating films is not particularly limited. For example, the first interlayer insulating film may be an inorganic material, and the second and third interlayer insulating films may be organic materials. . At this time, as the inorganic material, a film containing carbon such as silicon oxide, silicon nitride, silicon oxynitride, DLC or carbon nitride (CN), PSG (phosphorus glass), BPSG (phosphorus boron glass), an alumina film, or the like is used. be able to. As a formation method, a plasma CVD method, a low pressure CVD (LPCVD) method, an atmospheric pressure plasma, or the like can be used. Alternatively, an SOG film obtained by a coating method (for example, an SiOx film containing an alkyl group) can also be used.

On the other hand, as the organic material, a photosensitive or non-photosensitive organic material such as polyimide, acrylic, polyamide, resist or benzocyclobutene, or a heat-resistant organic resin such as siloxane can be used. Depending on the material, spin coating, dipping, spray coating, droplet discharge methods (inkjet method, screen printing, offset printing, etc.), doctor knife, roll coater, curtain coater, knife coater, etc. are adopted as the forming method. be able to. Note that the first to third interlayer insulating films may be formed by stacking the above materials.

A partition wall layer 409 (also called a bank, a bank, a barrier, or the like) is formed around the pixel electrode 11. As the partition layer 409, an organic resin material such as photosensitive or non-photosensitive polyimide, acrylic, polyamide, polyimide amide, resist or benzocyclobutene), a heat-resistant organic resin such as siloxane, and other inorganic insulating materials (SiN, SiO, SiON, SiNO, etc.), or a stack of these can be used. Here, a photosensitive organic resin covered with a silicon nitride film is used. As the insulator, either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light can be used.

Note that the side wall shape of the partition wall layer 409 is not particularly limited, but preferably has an S shape as shown in FIG. In other words, it is desirable to have a structure having an inflection point on the side surface of the partition wall layer 409. Thereby, the coverage of the electroluminescent layer 12 and the transparent electrode 13 formed on the pixel electrode 11 can be improved. However, the present invention is not limited to this, and a structure in which a curved surface having a radius of curvature is provided only at the upper end portion of the insulator may be employed.

Further, on the pixel electrode 11, the electroluminescent layer 12, the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, the low refractive index layer 16, and the like are formed in the same manner as in the first to third embodiments. In the illustrated configuration, the first embodiment is adopted, but the present invention is not limited to this. For example, the filling layer 17 described in Embodiment 3 may be provided in the space 415. Moreover, although the layer more than the passivation film 14 was formed in the whole substrate surface, of course, it is not limited to this.

In the structure shown in FIG. 5A, since the third interlayer insulating film 413 is further provided over the second interlayer insulating film 412, and the pixel electrode 11 is formed thereon, the light-emitting element 313 is formed. The area to be designed is not limited by the formation area of the transistor 312 and the wiring 414, and the degree of freedom in design increases. Accordingly, a display device having a desired aperture ratio can be obtained.

Next, FIG. 5B will be described in further detail. In the structure illustrated in FIG. 5B, a first interlayer insulating film 411 and a second interlayer insulating film 412 are provided over the transistor 312 and the element group 410. A wiring 414 is formed through an opening provided in the first interlayer insulating film 411 and the second interlayer insulating film 412. The wiring 414 functions as a source wiring or a drain wiring of the transistor 312 and the element group 410, a capacitor wiring of the capacitor 316, or the like. Further, the transistor 312 and the pixel electrode 11 are connected through at least one wiring 414. Since FIG. 5B is a dual emission type, the pixel electrode 11 uses a light-transmitting conductive film. In the illustrated configuration, the pixel electrode 11 is formed after the wiring 414 is formed. However, the opposite configuration may be employed. Further, the wiring 414 and the pixel electrode 11 may be formed in the same layer.

Note that in this embodiment, the first interlayer insulating film 411 provided over the transistor 312 has a barrier function that mainly prevents impurities such as Na, O ₂ , and moisture from entering the transistor 312 (this function). It is sometimes called a “cap insulating film” or the like.) It is desirable to form it as much as possible, but it can be omitted.

A partition wall layer 409 (also referred to as a bank or a bank) is formed around the pixel electrode 11. Further, on the pixel electrode 11, the electroluminescent layer 12, the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, the low refractive index layer 16, and the like are formed in the same manner as in the first to third embodiments. In the illustrated configuration, the first embodiment is adopted, but the present invention is not limited to this. For example, the filling layer 17 described in Embodiment 3 may be provided in the space 415.

The light emitting device according to the present invention is a top emission type (or a dual emission type) that emits light through the transparent electrode 13. For example, when the transparent electrode 13 functions as a cathode, an aluminum film of 1 nm to 10 nm or an aluminum film containing a small amount of Li may be used. When the Al film is used as the transparent electrode 13, the material in contact with the electroluminescent layer 12 can be formed of a material other than oxide, and the reliability of the light emitting device can be improved. Further, a light-transmitting layer (film thickness: 1 nm to 5 nm) made of CaF ₂ , MgF ₂ , or BaF ₂ may be formed as a cathode buffer layer before forming an aluminum film having a thickness of 1 nm to 10 nm. Further, in order to reduce the resistance of the cathode, as the transparent electrode 13, a 1 nm to 10 nm metal thin film and a transparent conductive film (ITO, indium zinc oxide alloy (In ₂ O ₃ —ZnO), zinc oxide (ZnO), etc.) It is good also as a laminated structure. Alternatively, in order to reduce the resistance of the cathode, an auxiliary electrode may be provided on the transparent electrode 13 in a region that does not become a light emitting region. Further, when the cathode is formed, a resistance heating method by vapor deposition is used, and the cathode may be selectively formed using a vapor deposition mask.

Note that the materials and structures of the first and second interlayer insulating films, the wiring 414, the partition wall layer 409, and the like are the same as those of the invention according to FIG.

In FIG. 5B, the pixel electrode 11 extends to a region where the capacitor 404 is formed, and the pixel electrode 11 also serves as a capacitor electrode of the capacitor 404. Further, the position where the connection film 407 is provided is different from that in FIG. 5A and is formed over the second interlayer insulating film 412. At this time, the connection film 407 and the element group 410 are connected via the wiring 414. Thus, a dual emission type display device can be obtained.

In addition, each characteristic part in the invention which concerns on FIG. 5 (A) and (B) can be implemented by mutually replacing or combining. This embodiment can be freely combined with the above embodiment mode and other embodiments.

In this example, another structure of the active matrix display device according to Example 1 will be described with reference to FIG. In the display device according to the present embodiment, a color filter is provided in each pixel portion, and at least one layer of the second or third interlayer insulating film or the partition layer 409 in Embodiment 1 or a part of the layer. Further, carbon or light-shielding metal particles are added. The details will be described below.

First, the top emission display device illustrated in FIG. 6A includes R, G, and B color filters 90 to 92 on a counter substrate 406. The color filters 90 to 92 can be made by a known material or a known method. The material for the electroluminescent layer is basically capable of emitting white light. In addition, as the second interlayer insulating film and the partition layer, a light-blocking interlayer insulating film 417 in which carbon (carbon) or metal particles are added to an organic material such as acrylic, polyimide, or siloxane, and a light-blocking partition layer. 416 is used. On the other hand, the third interlayer insulating film 413 is formed using a transparent organic resin such as acrylic, polyimide, or siloxane.

Here, the interlayer insulating film 417 having a light shielding property and the partition wall layer 416 having a light shielding property are formed using an organic material such as acrylic, polyimide, siloxane, or the like, using a shaker or an ultrasonic vibrator. After adding and stirring the metal particles having the above, filtration is carried out as necessary, and then the film is formed using a spin coating method. When carbon particles or metal particles are added to the organic material, a surfactant, a dispersant, or the like may be added so that the particles are uniformly mixed. Moreover, when adding carbon particles, it is good to adjust the addition amount so that the density | concentration of carbon particles may be 5 to 15% by weight percent. Further, the thin film formed by the spin coating method may be used as it is, but baking for the purpose of curing may be performed. The transmittance of the deposited thin film is 0% or nearly 0%. The reflectance is also 0% or a value close to 0%.

Note that the light-blocking interlayer insulating film 417 or the light-blocking partition wall 416 may include a transparent insulating layer in part. On the contrary, the third interlayer insulating film may include an insulating layer having a light shielding property in a part thereof. On the pixel electrode 11, the electroluminescent layer 12, the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, the low refractive index layer 16, and the like are formed as in the first to third embodiments. In the illustrated configuration, the first embodiment is adopted, but the present invention is not limited to this. For example, the filling layer 17 described in Embodiment 3 may be provided in the space 415. The materials and structures of the first interlayer insulating film 411 and the wiring 414 are the same as those in the first embodiment.

The top emission display device illustrated in FIG. 6A is provided with an interlayer insulating film 417 having a light shielding property and a partition wall layer 416 having a light shielding property, so that unnecessary light (light emitted from the bottom surface) is emitted from the light emitting layer. This also includes the light generated by the reflection of the light. That is, since the insulating film having a light-shielding property absorbs unnecessary light, the contour between pixels becomes clear and a high-definition image can be displayed. In addition, since the influence of unnecessary light can be suppressed by the arrangement of the light shielding film, a polarizing plate is not necessary, and a reduction in size, weight, and thickness can be realized. In addition, unnecessary light can be prevented from leaking to the transistor formation region of the pixel in particular, and active matrix driving with a highly reliable transistor is possible.

Next, in the dual emission display device illustrated in FIG. 6B, a transistor 312 and a first interlayer insulating film 411 are provided over a substrate 405, and an interlayer insulating film 417 having a light-blocking property is further provided. It has a configuration. The interlayer insulating film 417 having a light-shielding property is provided with an opening for allowing light from the light-emitting layer to pass therethrough, and the opening includes a pigment of red, green, and blue, and transmits light. The color filters 93 to 95 are formed by filling the resin having The resin containing the pigment is desirably formed selectively using a droplet discharge method. Further, the counter substrate 406 is provided with R, G, and B color filters 90 to 92 as in FIG. The color filters 90 to 92 can be made by a known material or a known method.

Further, as part of the second interlayer insulating film and the partition layer, a light-blocking interlayer insulating film 417 in which carbon or metal particles are added to an organic material such as acrylic, polyimide, or siloxane, and a light-blocking partition layer 416 are used. It has the structure using. The remaining part of the partition layer is formed using a transparent organic resin such as acrylic, polyimide, or siloxane. Note that the interlayer insulating film 417 having a light-shielding property may include a transparent insulating layer in a part thereof.

Here, the interlayer insulating film 417 having a light shielding property and the partition wall layer 416 having a light shielding property are formed using an organic material such as acrylic, polyimide, siloxane, or the like, using a shaker or an ultrasonic vibrator. After adding and stirring the metal particles having the above, filtration is carried out as necessary, and then the film is formed using a spin coating method. When carbon particles or metal particles are added to the organic material, a surfactant, a dispersant, or the like may be added so that the particles are uniformly mixed. Moreover, when adding carbon particles, it is good to adjust the addition amount so that the density | concentration of carbon particles may be 5 to 15% by weight percent. Further, the thin film formed by the spin coating method may be used as it is, but baking for the purpose of curing may be performed. The transmittance and reflectance of the thin film formed are both 0% or nearly 0%.

On the pixel electrode 11, the electroluminescent layer 12, the transparent electrode 13, the passivation film 14, the stress relaxation layer 15, the low refractive index layer 16, and the like are formed as in the first to third embodiments. In the illustrated configuration, the first embodiment is adopted, but the present invention is not limited to this. For example, the filling layer 17 described in Embodiment 3 may be provided in the space 415. The materials and structures of the first interlayer insulating film 411 and the wiring 414 are the same as those in the first embodiment.

The dual emission display device illustrated in FIG. 6B is provided with a light-blocking interlayer insulating film 417 and a light-blocking partition layer 416, so that an outline between pixels is formed by unnecessary light from the light-emitting layer. The effect of blurring can be suppressed. That is, since the insulating film having a light-shielding property absorbs unnecessary light, the contour between pixels becomes clear and a high-definition image can be displayed. In addition, since the influence of unnecessary light can be suppressed by the arrangement of the light shielding film, a polarizing plate is not necessary, and a reduction in size, weight, and thickness can be realized. In addition, unnecessary light can be prevented from leaking to the transistor formation region of the pixel in particular, and active matrix driving with a highly reliable transistor is possible.

In general, when a color filter is formed, a black matrix (a lattice-shaped or striped light-shielding film for optically separating R, G, and B pixels) is provided around the color filter. However, in the invention according to the configuration of FIGS. 6A and 6B described above, the light-blocking partition layer 416 or the light-blocking interlayer insulating film 417 is formed corresponding to the portion where the black matrix is to be provided. Has been. Therefore, as compared with the case where a black matrix is separately formed, the present invention improves the yield by making alignment easier, and reduces the cost because it is not necessary to add an extra process.

Note that in this embodiment, if at least one of the light-blocking partition layer 416 and the light-blocking interlayer insulating film 417 is formed, the above-described effects such as suppressing adverse effects due to unnecessary light from the light-emitting layer are provided. Can be demonstrated. Of course, it goes without saying that it is desirable to form both. Moreover, each characteristic part in the invention which concerns on FIG. 6 (A) and (B) can be implemented by mutually replacing or combining. This embodiment can be freely combined with the above embodiment mode and other embodiments.

In this example, an example of a structure of the light-emitting element according to any of the above embodiments is shown. As a reference sample, α-NPD (40 nm), Alq ₃ : DMQd (quinacridone derivative) (37.5 nm), Alq ₃ (20 nm), BzOS: Li (20 nm) on the anode ITO (110 nm) from the substrate side, A reference EL element having a structure in which the cathode ITO (110 nm) was laminated in this order was produced. Furthermore, an EL element (in this example, a structure in which stress relaxation layers are provided above and below the passivation film) having the layers shown in Table 1 formed on the cathode ITO was prepared, and a current density of 2.5 mA / A current of cm ² was passed, and the luminance of light emitted from the top surface was measured. As a result of comparison with the luminance (105.8 cd / m ² ) obtained by flowing the same current for the reference EL element, the increase in luminance shown in Table 1 was observed with respect to the luminance of the reference EL element. It was.

From the above measurement results, it was found that it is particularly preferable to use SiNO as the stress relaxation layer. Further, in the reference EL element, a dark spot was generated and the reliability was not so good. However, in the EL element having the laminated structure shown in Table 2 on the cathode ITO, all dark spots were observed. Was significantly reduced or dark spots were not observed, and the reliability was good. Of course, due to the presence of the stress relaxation layer, peeling and cracking of the SiN layer as the passivation film did not occur.

In other embodiments or examples, a new stress relaxation layer may be formed between the transparent electrode 13 and the passivation film as in this example. The material of the stress relaxation layer may be the same as or different from the stress relaxation layer provided on the passivation film.

In this example, an example of a method for manufacturing the passivation film 14 and the stress relaxation layer 15 in the present invention will be described. First, the passivation film 14 can be a silicon nitride film, a silicon oxide film, a silicon oxynitride film, a DLC film, a CN film, or a laminate thereof obtained by a sputtering method or a CVD method. In particular, a silicon nitride film formed by a high frequency sputtering method using silicon as a target is desirable. In addition, a dense silicon nitride film obtained by RF sputtering using a silicon target is contaminated with an active element such as a TFT (thin film transistor) due to alkali metal or alkaline earth metal such as sodium, lithium and magnesium. It effectively prevents fluctuations in value voltage and the like, and has a very high blocking effect against moisture and oxygen. In order to enhance the blocking effect, the oxygen and hydrogen contents in the silicon nitride film are 10 atomic% or less, preferably 1 atomic% or less.

Specific sputtering conditions are nitrogen gas or a mixed gas of nitrogen and rare gas, pressure is 0.1 to 1.5 Pa, frequency is 13 MHz to 40 MHz, power is 5 to 20 W / cm ² , and substrate temperature is room temperature to room temperature. The distance between the silicon target (1 to 10 Ωcm) and the substrate is 350 mm to 200 mm, and the back pressure is 1 × 10 ⁻³ Pa or less. Further, a heated rare gas may be sprayed on the back surface of the substrate. For example, the flow rate ratio is Ar: N ₂ = 20 sccm: 20 sccm, the pressure is 0.8 Pa, the frequency is 13.56 MHz, the power is 16.5 W / cm ² , the substrate temperature is 200 ° C., and the distance between the silicon target and the substrate is A dense silicon nitride film obtained at 60 mm and a back pressure of 3 × 10 ⁻⁵ Pa has an etching rate of 9 nm or less (referred to as an etching rate when etched at 20 ° C. using LAL500; the same applies hereinafter). Preferably, the hydrogen concentration is as low as 0.5 to 3.5 nm or less, and the hydrogen concentration is as low as 1 × 10 ²¹ atoms / cm ³ or less (preferably 5 × 10 ²⁰ atoms / cm ³ or less). . “LAL500” is “LAL500 SA buffered hydrofluoric acid” manufactured by Hashimoto Kasei Co., Ltd., and is an aqueous solution of NH ₄ HF ₂ (7.13%) and NH ₄ F (15.4%).

Further, the relative dielectric constant of the silicon nitride film formed by the sputtering method is 7.02 to 9.3, the refractive index is 1.91 to 2.13, the internal stress is 4.17 × 10 ⁸ dyn / cm ² , and the etching rate is 0.77 to 1.31 nm / min. Further, the sign of the numerical value of the internal stress changes depending on the compressive stress or the tensile stress, but only the absolute value is handled here. Further, the Si concentration obtained by RBS of the silicon nitride film by the sputtering method is 37.3 atomic%, and the N concentration is 55.9 atomic%. Further, the hydrogen concentration by SIMS of the silicon nitride film formed by the sputtering method is 4 × 10 ²⁰ atoms / cm ³ , the oxygen concentration is 8 × 10 ²⁰ atoms / cm ³ , and the carbon concentration is 1 × 10 ¹⁹ atoms / cm ³ . . Further, the silicon nitride film formed by the sputtering method has a transmittance of 80% or more in the visible light region.

In each of the above structures, the carbon-based thin film is a DLC film, a CN film, or an amorphous carbon film having a thickness of 3 to 50 m. Although the DLC film has SP ³ bonds as carbon-carbon bonds in a short-range order, it has an amorphous structure on a macro scale. The composition of the DLC film is 70 to 95 atomic% for carbon and 5 to 30 atomic% for hydrogen, and is very hard and excellent in insulation. In addition, the DLC film is a thin film that is chemically stable and hardly changes. The DLC film has a thermal conductivity of 200 to 600 W / m · K and a refractive index of 2.3 to 2.4, so that heat generated during driving can be dissipated. Such a DLC film is also characterized by low gas permeability such as water vapor and oxygen. It is also known to have a hardness of 15 to 25 GPa as measured by a microhardness meter.

The DLC film is formed by a plasma CVD method (typically, an RF plasma CVD method, a microwave CVD method, an electron cyclotron resonance (ECR) CVD method, a hot filament CVD method, etc.), a combustion flame method, a sputtering method, an ion beam evaporation method, It can be formed by a laser vapor deposition method or the like. Whichever film formation method is used, the DLC film can be formed with good adhesion. The DLC film is formed by placing the substrate on the cathode. Alternatively, a dense and hard film can be formed by applying a negative bias and utilizing ion bombardment to some extent. The reactive gas used for forming the DLC film is hydrogen gas and a hydrocarbon gas (for example, CH ₄ , C ₂ H ₂ , C ₆ H _6, etc.), ionized by glow discharge, and negative self-bias. The film is formed by accelerating and colliding ions with the cathode subjected to the irradiation. By doing so, a dense and smooth DLC film can be obtained. The DLC film is an insulating film that is transparent or translucent to visible light. In the present specification, transparent to visible light means that the visible light transmittance is 80 to 100%, and translucent to visible light is a visible light transmittance of 50 to 80%. Refers to that.

In addition, as a reaction gas used for forming the CN film, a nitrogen gas and a hydrocarbon gas (for example, C ₂ H ₂ , C ₂ H _4, etc.) may be used.

Next, the stress relaxation layer 15 will be described. The stress relaxation layer is made of an alloy film such as MgO, SrO ₂ , SrO, CaN, or α-NPD (4,4′-bis- [N- (naphthyl) -N-phenyl-amino] biphenyl), BCP (vasocuproin) , MTDATA (4,4 ′, 4 ″ -tris (N-3-methylphenyl-N-phenyl-amino) triphenylamine), Alq ₃ (tris-8-quinolinolato aluminum complex) As described above, the stress relaxation layer may be made of the same material as at least one of the layers constituting the layer containing the organic compound (electroluminescent layer) sandwiched between the cathode and the anode. The stress relaxation layer may be a polymer material film containing an organic compound obtained by a coating method (inkjet method or spin coating method), for example, polyaniline. A polythiophene derivative (PEDOT), etc. may be used, although any of the above materials is a film having low film stress and transparency, it is suitable in terms of having further hygroscopicity. is there.

In this embodiment, another configuration of the active matrix display device according to Embodiment 1 will be described with reference to FIG. The active matrix display device illustrated in FIG. 7A is characterized in that a low refractive index layer 418 is provided on the upper and lower surfaces of the counter substrate 406 or at least one surface thereof. The low refractive index layer 418 has a refractive index higher than that of air and lower than a refractive index (n = 1.5) of the counter substrate 406 (typically, a glass substrate), and is lithium fluoride (LiF, n = 1.30 to 1.39), magnesium fluoride (MgF ₂ , n = 1.38 to 1.40), calcium fluoride (CaF ₂ , n = 1.23 to 1.45), barium fluoride (BaF) ₂ , n = 1.47) or the like. Note that in the case where the low refractive index layers 418 are provided on the upper and lower surfaces of the counter substrate 406, the materials may be the same or different.

A low-refractive index layer 418 having a LiF film of 30 nm formed on both surfaces of a glass substrate as a counter substrate was used to produce a 1 × 1 EL element, and the luminance was measured at a current density of ^2.5 mA / cm ^2. Regardless of the film thickness of the cathode (transparent electrode 13), an increase in luminance of about 3% was observed.

Further, the counter substrate is (1) glass only, (2) glass is laminated on the low refractive index layer, (3) the low refractive index layer is laminated on the glass, and (4) glass is laminated on the low refractive index layer. When the transmittance was measured separately in the case of laminating a low refractive index layer, it was found that the transmittance improved in the order of the numbers, that is, the luminance increased.

In the active matrix display device illustrated in FIG. 7B, a low refractive index layer 418 is provided on the top and bottom surfaces of the counter substrate 406 or at least one surface thereof, and the low refractive index layer 16 on the light emitting element 313 side is provided. The filling layer 17 is provided between the low refractive index layers 418 provided on the counter substrate 406. The low refractive index layer 418 can be formed using a material similar to that shown in FIG. Further, it is desirable that the filling layer 17 has a refractive index substantially equal to or intermediate between the refractive index of the low refractive index layer 16 or the low refractive index layer 418. For example, when the low refractive index layers 16 and 418 are both LiF (n = 1.30 to 1.39), a material having a refractive index of about 1.2 to 1.5 is used as the filling layer 17. It is good. For example, an inert liquid fluorinate (n = 1.23 to 1.31) containing fluorine may be used. Alternatively, using a film of polytetrafluoroethylene (n = 1.36), (polymethyl methacrylate (PMMA, n = 1.49), polymer containing fluorine (n = 1.35 to 1.43) Also good.

However, the material is not limited to the above material as long as it has a value approximately equal to or intermediate between the refractive indexes of both low refractive index layers. Further, the lower limit of the refractive index may be about 1.2 or less because the effect of providing the filling layer 17 is exhibited as long as it is larger than air (n = 1). The filling layer 17 can be formed by sealing a light emitting element with the counter substrate 406 provided with the low refractive index layer 418 and then injecting a liquid under vacuum. Alternatively, it can be manufactured using a droplet discharge method typified by an inkjet method, a dropping method, a printing method, a coating method, or the like.

In this embodiment, the case of an active matrix display device has been described. However, the present invention has the technical features of the inventions according to Embodiments 1 to 3, and a structure in which a low refractive index layer is formed on a counter substrate. Can be applied to a passive display device. Note that other configurations of the invention shown in FIG. 7 are based on other embodiments or examples. This embodiment can be freely combined with the above embodiment mode and other embodiments.

In this embodiment, examples of pixel circuits applicable to the present invention other than the pixel circuit shown in FIG. 4A will be described with reference to FIGS. FIG. 8A illustrates a pixel circuit in which an erasing transistor 340 and an erasing gate line Ry are newly provided in the pixel 310 illustrated in FIG. The arrangement of the transistor 340 can forcibly create a state in which no current flows to the light-emitting element 313. Therefore, without waiting for signal writing to all the pixels 310, the lighting period can be set at the same time or immediately after the start of the writing period. Can start. Therefore, the duty ratio is improved, and moving images can be displayed particularly well.

8B, the transistor 312 of the pixel 310 illustrated in FIG. 4A is deleted, and transistors 341 and 342 and a power supply line Vax (x is a natural number, 1 ≦ x ≦ l) are newly provided. Pixel circuit. The power supply line Vax is connected to the power supply 343. In this configuration, the potential of the gate electrode of the transistor 341 is fixed by operating the transistor 341 in the saturation region by connecting the gate electrode of the transistor 341 to the power supply line Vax held at a constant potential. Further, the transistor 342 is operated in a linear region, and a video signal including information on lighting or non-lighting of a pixel is input to a gate electrode thereof. Since the value of the source-drain voltage of the transistor 342 operating in the linear region is small, a slight change in the gate-source voltage of the transistor 342 does not affect the value of the current flowing through the light-emitting element 313. Accordingly, the value of the current flowing through the light emitting element 313 is determined by the transistor 341 operating in the saturation region. In the present invention having the above structure, luminance unevenness of the light-emitting element 313 due to variation in characteristics of the transistor 341 can be improved and image quality can be improved. This embodiment can be freely combined with the above embodiment mode and other embodiments.

In this embodiment, a stacked structure of the wiring 414 (including the second power supply 318; the same applies to this embodiment) and the pixel electrode 11 in the above embodiment will be described with reference to FIG. Each drawing of FIG. 9 shows only a part of the light emitting element in the pixel region, and illustration of a passivation film, a stress relaxation layer, a low refractive index layer, and the like is omitted.

FIG. 9A shows a case where the wiring structure is a laminated structure of Mo600 and an alloy 601 containing aluminum, and the pixel electrode 11 is ITO602. As the alloy 601 containing aluminum, an aluminum alloy containing carbon, nickel, cobalt, iron, silicon, or the like is desirable. These contents include, for example, 0.1 to 3.0 atomic% of carbon, 0.5 to 7.0 atomic% of at least one element among nickel, cobalt, and iron, and 0.5 to 2 of silicon. It is preferable to set it to 0 atomic%. One of the characteristics of this material is that the resistance value is as low as 3.0 to 5.0 Ωcm. Here, Mo600 functions as a barrier metal.

Thus, when the alloy 601 containing aluminum contains 0.5% or more of at least one element of nickel, cobalt, and iron, the electrode potential of the ITO 602 can be brought close to and directly in contact with the ITO 602. Contact is possible. In addition, the heat resistance of the alloy 601 containing aluminum is improved. Moreover, generation | occurrence | production of a hillock can be suppressed by making content of carbon 0.1% or more. Further, even when silicon is contained, there is an advantage that hillocks are hardly generated even when heat treatment is performed at a high temperature.

FIG. 9B shows a case where an alloy 603 containing aluminum is used as the wiring and ITO 602 is used as the pixel electrode 11. Here, the alloy 603 containing aluminum has a structure containing at least nickel. After forming the alloy 603 containing aluminum, nickel contained in the alloy oozes out and chemically reacts with Si in the silicon semiconductor layer 608 of the active element (for example, TFT) for driving the pixel region. Nickel silicide 607 is formed, and there is a merit that the bondability is improved.

FIG. 9C shows a case where an alloy 604 containing aluminum is stacked as a wiring and ITO 605 is stacked as a pixel electrode 11. In particular, it has been experimentally found that flatness is remarkably improved when a laminated structure of a combination of both is employed. For example, the flatness is about twice as high as that of the wiring structure in which TiN is formed on the Al-Si alloy and the laminated structure of ITO, and the wiring structure in which TiN is formed on the Al-Si alloy and the laminated structure of ITSO. It showed goodness.

FIG. 9D shows the case where alloys 604 and 606 containing aluminum are used as wirings and pixel electrodes.

Since the alloy containing aluminum can be easily patterned by wet etching, it can be used widely regardless of wiring and pixel electrodes. However, since the alloy containing aluminum is excellent in reflectivity, it is suitable for the top emission type. In the case of a dual emission display device, it is necessary to form a thin film so that light can pass through the wiring or the pixel electrode. Note that this embodiment can be freely combined with the above embodiment mode and other embodiments.

As an electronic device using a display device including a pixel region including a light emitting element according to the present invention, a television device (television, television receiver), a digital camera, a digital video camera, a mobile phone device (mobile phone), a PDA Such as a portable information terminal such as a portable game machine, a monitor, a computer, an audio reproducing device such as a car audio, and an image reproducing device equipped with a recording medium such as a home game machine. A specific example thereof will be described with reference to FIG.

A portable information terminal using the display device of the present invention illustrated in FIG. 10A includes a main body 9201, a display portion 9202, and the like, and can display a high-definition image according to the present invention. A digital video camera using the display device of the present invention illustrated in FIG. 10B includes display portions 9701 and 9702 and the like, and can display a high-definition image according to the present invention. A portable terminal using the display device of the present invention illustrated in FIG. 10C includes a main body 9101, a display portion 9102, and the like, and can display a high-definition image according to the present invention. A portable television device using the display device of the present invention illustrated in FIG. 10D includes a main body 9301, a display portion 9302, and the like, and can display a high-definition image according to the present invention. A portable computer using the display device of the present invention illustrated in FIG. 10E includes a main body 9401, a display portion 9402, and the like, and can display a high-definition image according to the present invention. A television set using the display device of the present invention illustrated in FIG. 10F includes a main body 9501, a display portion 9502, and the like, and can display a high-definition image according to the present invention. Further, when an interlayer insulating film having a light shielding property or a partition wall layer having a light shielding property is provided as in the above embodiment, the influence of unnecessary light can be suppressed, so that a polarizing plate is not required and a small size. , Lighter and thinner.

Here, the main configuration of the television apparatus will be briefly described with reference to the block diagram of FIG. In the figure, an EL display panel 801 is manufactured by using the display device according to the present invention. Further, as a method of connecting the EL display panel 801 and an external circuit, (1) a pixel portion of the display panel and scanning line side driving When the circuit 803 is integrally formed on the substrate and the signal line side driver circuit 802 is separately mounted as a driver IC, (2) only the pixel portion of the display panel is formed and the scanning line side driver circuit 803 and the signal line side driver are formed. When the circuit 802 is mounted by the TAB method, (3) the scanning line side driving circuit 803 and the signal line side driving circuit 802 are mounted by the COG method on and around the pixel portion of the display panel. However, any form is acceptable.

As other external circuit configurations, on the input side of the video signal, among the signals received by the tuner 804, the video wave amplifier circuit 805 that amplifies the video signal, and the signal output therefrom is each of red, green, and blue colors And a control circuit 807 for converting the video signal into the input specification of the driver IC. The control circuit 807 outputs signals to the scanning line side and the signal line side, respectively. In the case of digital driving, a signal dividing circuit 808 may be provided on the signal line side so that an input digital signal is divided into m pieces and supplied.

Of the signals received by the tuner 804, the audio signal is sent to the audio wave amplification circuit 809, and the output is supplied to the speaker 813 through the audio signal processing circuit 810. The control circuit 811 receives control information on the receiving station (reception frequency) and volume from the input unit 812, and sends a signal to the tuner 804 and the audio signal processing circuit 810.

A television receiver as shown in FIG. 10F can be completed by incorporating such an external circuit and an EL display panel in a housing. Of course, the present invention is not limited to a television receiver, and is applied to various uses as a display medium of a particularly large area such as a monitor of a personal computer, an information display board in a railway station or airport, an advertisement display board in a street, etc. can do. Note that this embodiment can be freely combined with the above embodiment mode or other embodiments.

The display device of the present invention can be used as an ID card capable of transmitting and receiving data without contact by mounting a functional circuit such as a memory or a processing circuit or an antenna coil. An example of the configuration of such an ID card will be described with reference to the drawings.

FIG. 12A shows one mode of an ID card incorporating a display device according to the present invention. The ID card shown in FIG. 12A is a non-contact type that transmits and receives data with a reader / writer of a terminal device in a non-contact manner. Reference numeral 101 denotes a card body, and 102 corresponds to a pixel portion of a display device mounted on the card body 101.

FIG. 12B shows a configuration of the card substrate 103 included in the card main body 101 shown in FIG. An ID chip 104 formed of a thin semiconductor film and a display device 105 according to the above embodiment or examples are attached to the card substrate 103. Both the ID chip 104 and the display device 105 are formed on a separately prepared substrate and then transferred onto the card substrate 103. As a transfer method, there are a method in which a thin film integrated circuit including a large number of TFTs is manufactured and then attached using small vacuum tweezers or the like, or a method of selectively attaching using a UV light irradiation method. The same can be applied to the pixel portion and the driver circuit portion in the display device. A portion formed using a thin semiconductor film including the ID chip 104 and the display device 105 and transferred to the card substrate after the formation is referred to as a thin film portion 107.

An integrated circuit 106 manufactured using TFT is mounted on the card substrate 103. A method for mounting the integrated circuit 106 is not particularly limited, and a known COG method, wire bonding method, TAB method, or the like can be used. The integrated circuit 106 is electrically connected to the thin film portion 107 via a wiring 108 formed on the card substrate 103.

An antenna coil 109 that is electrically connected to the integrated circuit 106 is formed on the card substrate 103. Since the antenna coil 109 can transmit and receive data to and from the terminal device in a non-contact manner using electromagnetic induction, the non-contact ID card is physically worn compared to the contact type. Not easily damaged. Furthermore, the non-contact type ID card can also be used as a tag (wireless tag) for managing information without contact. A non-contact type ID card has a remarkably high amount of information that can be managed compared to a barcode that can also read information without contact. In addition, the distance from the terminal device that can read information can be made longer than when a barcode is used.

FIG. 12B shows an example in which the antenna coil 109 is formed on the card substrate 103, but an antenna coil that is separately manufactured may be mounted on the card substrate 103. For example, a coil formed by winding a copper wire or the like and sandwiching the copper wire between two plastic films having a thickness of about 100 μm can be used as an antenna coil. An antenna coil may be built in the thin film integrated circuit. In FIG. 12B, only one antenna coil 109 is used for one ID card, but a plurality of antenna coils 109 may be used.

Note that FIG. 12 shows a form of an ID card on which the display device 105 is mounted. However, the present invention is not limited to this configuration, and a display device is not necessarily provided. However, by providing the display device, the face photo data can be displayed on the display device, and the face photo replacement can be made more difficult than when the printing method is used. In addition, information other than the face photo can be displayed, and the ID card can be enhanced.

As the card substrate 103, a flexible plastic substrate can be used. As the plastic substrate, ARTON: JSR made of norbornene resin with a polar group can be used. Polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), polycarbonate (PC), nylon, polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI), poly A plastic substrate such as arylate (PAR), polybutylene terephthalate (PBT), or polyimide can be used.

In this embodiment, the electrical connection between the ID chip and the thin film integrated circuit is not limited to the form shown in FIG. For example, the terminal of the ID chip and the terminal of the thin film integrated circuit may be directly connected with an anisotropic conductive resin or solder instead of via the wiring formed on the card substrate.

In FIG. 12, the connection between the thin film integrated circuit and the wiring formed on the card substrate may be connected by a wire bonding method, a flip chip method using a solder ball, or anisotropic conductivity. It may be directly connected with resin or solder, or may be connected using other methods. Note that this embodiment can be freely combined with the above embodiment mode and other embodiments. The display device according to the present invention can be used by being incorporated in a semiconductor device such as an ID tag, a wireless chip, and a wireless tag as well as an ID card.

The light-emitting element of the present invention described above can be applied to a pixel portion of a light-emitting device having a display function and an illumination portion of a light-emitting device having a lighting function. In this example, a circuit configuration and a driving method of a light-emitting device having a display function will be described with reference to FIGS.

FIG. 13 is a schematic view of a light emitting device to which the present invention is applied as viewed from above. In FIG. 13, a pixel portion 6511, a source signal line driver circuit 6512, a write gate signal line driver circuit 6513, and an erase gate signal line driver circuit 6514 are provided over a substrate 6500. The source signal line drive circuit 6512, the write gate signal line drive circuit 6513, and the erase gate signal line drive circuit 6514 are each an FPC (flexible printed circuit) 6503 which is an external input terminal via a wiring group. Connected. The source signal line driver circuit 6512, the writing gate signal line driver circuit 6513, and the erasing gate signal line driver circuit 6514 receive a video signal, a clock signal, a start signal, a reset signal, and the like from the FPC 6503, respectively. . A printed wiring board (PWB) 6504 is attached to the FPC 6503. Note that the driver circuit portion is not necessarily provided over the same substrate as the pixel portion 6511 as described above. For example, an IC chip mounted on an FPC on which a wiring pattern is formed (TCP) or the like is used. It may be used and provided outside the substrate.

In the pixel portion 6511, a plurality of source signal lines extending in the column direction are arranged side by side in the row direction. In addition, current supply lines are arranged side by side in the row direction. In the pixel portion 6511, a plurality of gate signal lines extending in the row direction are arranged side by side in the column direction. In the pixel portion 6511, a plurality of sets of circuits including light-emitting elements are arranged.

FIG. 14 is a diagram illustrating a circuit for operating one pixel. The circuit illustrated in FIG. 14 includes a first transistor 901, a second transistor 902, and a light-emitting element 903. Each of the first transistor 901 and the second transistor 902 is a three-terminal element including a gate electrode, a drain region, and a source region, and has a channel region between the drain region and the source region. Here, since the source region and the drain region vary depending on the structure and operating conditions of the transistor, it is difficult to limit which is the source region or the drain region. Therefore, in this embodiment, regions functioning as a source or a drain are referred to as a first electrode and a second electrode, respectively.

The gate signal line 911 and the writing gate signal line driving circuit 913 are provided so as to be electrically connected or disconnected by a switch 918. The gate signal line 911 and the erasing gate signal line driver circuit 914 are provided so as to be electrically connected or disconnected by a switch 919. The source signal line 912 is provided so as to be electrically connected to either the source signal line driver circuit 915 or the power source 916 by the switch 920. The gate of the first transistor 901 is electrically connected to the gate signal line 911. The first electrode of the first transistor 901 is electrically connected to the source signal line 912, and the second electrode is electrically connected to the gate electrode of the second transistor 902. The first electrode of the second transistor 902 is electrically connected to the current supply line 917, and the second electrode is electrically connected to one electrode included in the light-emitting element 903. Note that the switch 918 may be included in the write gate signal line driver circuit 913. The switch 919 may also be included in the erase gate signal line driver circuit 914. Further, the switch 920 may also be included in the source signal line driver circuit 915.

There is no particular limitation on the arrangement of transistors, light-emitting elements, and the like in the pixel portion. For example, they can be arranged as shown in the top view of FIG. In FIG. 15, the first electrode of the first transistor 1001 is connected to the source signal line 1004, and the second electrode is connected to the gate electrode of the second transistor 1002. The first electrode of the second transistor 1002 is connected to the current supply line 1005, and the second electrode is connected to the electrode 1006 of the light emitting element. Part of the gate signal line 1003 functions as a gate electrode of the first transistor 1001.

Next, a driving method will be described. FIG. 16 is a diagram for explaining the operation of a frame over time. In FIG. 16, the horizontal direction represents the passage of time, and the vertical direction represents the number of scanning stages of the gate signal line.

When image display is performed using the light emitting device of the present invention, the screen rewriting operation and the display operation are repeatedly performed during the display period. The number of rewrites is not particularly limited, but is preferably at least about 60 times per second so that a person viewing the image does not feel flicker. Here, a period during which one screen (one frame) is rewritten and displayed is referred to as one frame period.

As shown in FIG. 16, one frame is time-divided into four subframes 501, 502, 503, and 504 including a writing period 501a, 502a, 503a, and 504a and a holding period 501b, 502b, 503b, and 504b. . A light emitting element to which a signal for emitting light is given is in a light emitting state in the holding period. The ratio of the length of the holding period in each subframe is as follows: first subframe 501: second subframe 502: third subframe 503: fourth subframe 504 = 2 ³ : 2 ² : 2 ¹ : 2 ⁰ = 8: 4: 2: 1. As a result, 4-bit gradation can be expressed. However, the number of bits and the number of gradations are not limited to those described here. For example, eight subframes may be provided so that 8-bit gradation can be performed.

An operation in one frame will be described. First, in the subframe 501, the write operation is performed in order from the first row to the last row. Therefore, the start time of the writing period differs depending on the row. From the row in which the writing period 501a ends, the storage period 501b is started in order. In the holding period, the light-emitting element to which a signal for emitting light is given is in a light-emitting state. Further, the processing proceeds to the next subframe 502 in order from the row in which the holding period 501b ends, and the writing operation is performed in order from the first row to the last row as in the case of the subframe 501. The operation as described above is repeated until the holding period 504b of the subframe 504 ends. When the operation in the subframe 504 is completed, the process proceeds to the next frame. Thus, the accumulated time of the light emission in each subframe is the light emission time of each light emitting element in one frame. Various display colors having different brightness and chromaticity can be formed by changing the light emission time for each light emitting element and combining them in various ways within one pixel.

When it is desired to forcibly end the holding period in the row that has already finished writing and has shifted to the holding period before the writing up to the last row is completed as in the subframe 504, after the holding period 504b. It is preferable to provide an erasing period 504c and control to forcibly enter a non-light emitting state. Then, the row that is forcibly set to the non-light-emitting state is kept in the non-light-emitting state for a certain period (this period is referred to as a non-light-emitting period 504d). Then, as soon as the writing period of the last row ends, the next (or frame) writing period starts in order from the first row. In order to perform writing in the pixels in a certain row in this way and input an erasing signal for making the pixels in a non-light-emitting state in the pixels in a certain row, two horizontal periods are provided as shown in FIG. And one period is used for writing and the other period is used for erasing. Each gate signal line 911 is selected within the divided horizontal period, and a corresponding signal is input to the source signal line 912 at that time. For example, in one horizontal period, the i-th row is selected in the first half and the j-th row is selected in the second half. Then, in one horizontal period, it is possible to operate as if two rows were selected at the same time. That is, video signals are written to the pixels in the writing periods 501a to 504a using the writing period of each one horizontal period. In this case, no pixel is selected in the erase period of one horizontal period. Further, the signal written to the pixel in the erasing period 504c is erased using another erasing period of one horizontal period. At this time, no pixel is selected in the writing period of one horizontal period. Accordingly, a display device having a pixel with a high aperture ratio can be provided, and the yield can be improved.

In this embodiment, the subframes 501 to 504 are arranged in order from the longest holding period. However, the subframes 501 to 504 are not necessarily arranged as in this embodiment, and are arranged in order from the shortest holding period, for example. Alternatively, the long holding period and the short holding period may be arranged at random. In addition, the subframe may be further divided into a plurality of frames. That is, the gate signal line may be scanned a plurality of times during the period when the same video signal is applied.

Here, the operation of the circuit shown in FIG. 14 in the writing period and the erasing period will be described. First, the operation in the writing period will be described. In the write period, the i-th (i is a natural number) gate signal line 911 is electrically connected to the write gate signal line drive circuit 913 via the switch 918, and the erase gate signal line drive circuit 914 Is disconnected. The source signal line 912 is electrically connected to the source signal line driver circuit 915 through the switch 920. Here, a signal is input to the gate of the first transistor 901 connected to the gate signal line 911 in the i-th row, and the first transistor 901 is turned on. At this time, video signals are simultaneously input to the source signal lines from the first column to the last column. Note that the video signals input from the source signal lines 912 in each column are independent from each other. A video signal input from the source signal line 912 is input to the gate electrode of the second transistor 902 through the first transistor 901 connected to each source signal line. At this time, on / off of the second transistor 902 is controlled by a signal input to the gate electrode of the second transistor 902. When the second transistor 902 is turned on, a voltage is applied to the light-emitting element 903, and a current flows through the light-emitting element 903. That is, light emission or non-light emission of the light-emitting element 903 is determined by a signal input to the gate electrode of the second transistor 902. For example, in the case where the second transistor 902 is a p-channel transistor, the light-emitting element 903 emits light by inputting a low level signal to the gate electrode of the second transistor 902. On the other hand, in the case where the second transistor 902 is an n-channel transistor, the light-emitting element 903 emits light when a high level signal is input to the gate electrode of the second transistor 902.

Next, the operation in the erasing period will be described. In the erasing period, the gate signal line 911 in the j-th row (j is a natural number) is electrically connected to the erasing gate signal line driving circuit 914 via the switch 919, and is connected to the writing gate signal line driving circuit 913. Not connected. The source signal line 912 is electrically connected to the power source 916 through the switch 920. Here, a signal is input to the gate of the first transistor 901 connected to the gate signal line 911 in the j-th row, and the first transistor 901 is turned on. At this time, the erase signal is simultaneously input to the source signal lines from the first column to the last column. The erase signal input from the source signal line 912 is input to the gate electrode of the second transistor 902 through the first transistor 901 connected to each source signal line. At this time, the second transistor 902 is turned off by the erase signal input to the gate electrode of the second transistor 902 and current supply from the current supply line 917 to the light-emitting element 903 is blocked. Then, the light emitting element 903 is forced to emit no light. For example, in the case where the second transistor 902 is a p-channel transistor, the light-emitting element 903 does not emit light when a high level signal is input to the gate electrode of the second transistor 902. On the other hand, in the case where the second transistor 902 is an n-channel transistor, the light emitting element 903 does not emit light by inputting a low level signal to the gate electrode of the second transistor 902.

In the erasing period, a signal for erasing the j-th row is input by the operation as described above. However, as described above, the j-th row may be an erasing period, and the other rows (i-th row) may be a writing period. In such a case, it is necessary to input a signal for erasure to the j-th row and a signal for writing to the i-th row by using the source signal line in the same column, and will be described below. It is preferable to perform such an operation.

The gate signal line 911 and the erasing gate signal line drive circuit 914 are immediately disconnected after the light emitting element 903 in the j−1th row does not emit light by the operation in the erasing period, and the switch 920 And the source signal line 912 and the source signal line driver circuit 915 are connected. Then, the source signal line 912 and the source signal line driver circuit 915 are connected, and the switch 918 is switched to connect the gate signal line 911 and the writing gate signal line driver circuit 913. Then, a signal is selectively input from the write gate signal line driver circuit 913 to the gate signal line 911 in the i-th row, the first transistor 901 is turned on, and the source signal line driver circuit 915 supplies one column. A video signal for writing is input to the source signal line 912 from the first to the last column. By this video signal, the i-th light emitting element 903 emits light or does not emit light.

Immediately after the writing period for the i-th row is completed as described above, the erasing period for the j-th row is started. For this purpose, the switch 918 is switched to disconnect the gate signal line and the write gate signal line drive circuit 913, and the switch 920 is switched to connect the source signal line to the power source 916. In addition, the gate signal line 911 and the write gate signal line drive circuit 913 are disconnected, and the gate signal line 911 is switched to the erasure gate signal line drive circuit 914 by switching the switch 919. Then, a signal is selectively input from the erasing gate signal line driver circuit 914 to the gate signal line 911 in the j-th row to turn on the first transistor 901 and an erasing signal is input from the power supply 916. Then, the light emitting element 903 is forcibly turned off by the erase signal. In this way, immediately after the erasing period of the j-th row is finished, the writing period of the (i + 1) -th row is started. Thereafter, similarly, the erasing period and the writing period may be repeated until the erasing period of the last row is operated.

In this embodiment, the mode in which the writing period of the i-th row is provided between the erasing period of the j−1-th row and the erasing period of the j-th row is not limited to this. An i-th writing period may be provided between the period and the (j + 1) -th erasing period.

In this embodiment, when the non-light emission period 504d is provided as in the subframe 504, the erase gate signal line driver circuit 914 and a certain gate signal line are disconnected from each other, and the write gate The operation of connecting the signal line driver circuit 913 and the other gate signal lines is repeated. Such an operation may be performed particularly in a frame in which a non-light emitting period is not provided. Note that this embodiment can be freely combined with the above embodiment mode or other embodiments.

In the light emitting device according to the present invention, since the stress relaxation layer is formed in contact with the upper surface or the lower surface of the passivation film, the thickness of the passivation film is increased without being adversely affected by peeling or cracking of the passivation film. As a result, an extremely high blocking effect can be obtained. Therefore, a highly reliable light-emitting element can be provided with high yield. In addition, when a stress relaxation layer is provided on the upper surface of the passivation film (including the case where the stress relaxation layer is provided on both sides), the stress relaxation is achieved by making the refractive index of the low refractive index layer smaller than the refractive index of the stress relaxation layer. The difference in refractive index between the layer and the space can be reduced, and the light extraction efficiency to the external space can be improved.

A light-emitting element having the above-described effects can be employed in a display device typified by an EL display. The display device is a method in which an electroluminescent layer is formed between two types of stripe-shaped electrodes provided so as to be orthogonal to each other (simple matrix method), or opposed to pixel electrodes arranged in a matrix connected to a TFT. The light emitting element according to the present invention can be applied to both a simple matrix method and an active matrix method, which are roughly classified into two types (active matrix method) in which an electroluminescent layer is formed between electrodes. it can. Further, the display device can be mounted on any electronic device or ubiquitous product such as an ID card, and the applicability of the present invention is extremely diverse.

3A and 3B illustrate a structure of a light-emitting element according to the present invention. The figure explaining the structure of the light emitting element which concerns on this invention (when a filler layer is provided) FIG. 6 illustrates a structure of a light-emitting element according to the present invention (when a stress relaxation layer is provided below a passivation film). The equivalent circuit schematic of the pixel area of the display apparatus which concerns on this invention, and the top view of the display panel part of a display apparatus Sectional drawing of the display apparatus which concerns on this invention Sectional drawing of the display apparatus which concerns on this invention (when a color filter is provided) Sectional drawing of the display apparatus which concerns on this invention (when a low-refractive-index layer is provided in the opposing board | substrate) Equivalent circuit diagram of pixel area of display device according to the present invention Sectional view showing the case where the wiring has a laminated structure FIG. 11 is a diagram showing an electronic device using a display device according to the invention. The block diagram which shows the main structures of the television apparatus using the display apparatus which concerns on this invention The figure explaining the ID card using the display apparatus which concerns on this invention Top view of light emitting device according to the present invention The figure showing the circuit for operating one pixel in the light-emitting device which concerns on this invention The top view of the pixel area | region in the light-emitting device which concerns on this invention The figure explaining the operation of the frame over time The figure explaining the structure of the conventional light emitting element The figure explaining the method of selecting a plurality of gate signal lines simultaneously in one horizontal period

Explanation of symbols

1: Substrate 2: Electrode 3: Hole transport layer 4: Light-emitting layer 5: Electron injection layer 6: Transparent electrode 7: Moisture-proof layer 8: Antireflection layer 10: Substrate 11: Pixel electrode 12: Electroluminescent layer 13: Transparent electrode 14: Passivation film 14a: Silicon nitride film 14b: Silicon oxide film 14c: Silicon nitride film 15: Stress relaxation layer 15a: Stress relaxation layer 15b: Stress relaxation layer 16: Low refractive index layer 17: Filling layer 18: Counter substrate 90: Color filter 91: Color filter 92: Color filter 93: Color filter 94: Color filter 95: Color filter 101: Card body 102: Pixel portion 103: Card substrate 104: ID chip 105: Display device 106: Integrated circuit 107: Thin film portion 108: wiring 109: antenna coil 310: pixel 311: transistor 312: transistor 313: light emitting element 316: capacitive element 317: first power source 318: second power source 340: transistor 341: transistor 342: transistor 343: power source 400: display area 401: gate driver 402: gate driver 403: source driver 404: capacitor element 405: substrate 406: opposite Substrate 407: Connection film 408: Sealing material 409: Partition layer 410: Element group 411: First interlayer insulating film 412: Second interlayer insulating film 413: Third interlayer insulating film 414: Wiring 415: Space 416: Light shielding Barrier layer 417: light-shielding interlayer insulating film 418: low refractive index layer 501: subframe 501a: writing period 501b: holding period 502: subframe 502a: writing period 502b: holding period 503: subframe 503a: Write period 503b: retention period 504: sub Frame 504a: writing period 504b: retention 504c: erase period 504d: non-emission period 600: Mo
601: Alloy containing aluminum 602: ITO
603: Alloy containing aluminum 604: Alloy containing aluminum 605: ITO
606: Alloy containing aluminum 607: Nickel silicide 608: Silicon semiconductor layer 801: EL display panel 802: Signal line side drive circuit 803: Scan line side drive circuit 804: Tuner 805: Video wave amplifier circuit 806: Video signal processing circuit 807 : Control circuit 808: signal dividing circuit 809: audio wave amplifier circuit 810: audio signal processing circuit 811: control circuit 812: input unit 813: speaker 901: first transistor 902: second transistor 903: light emitting element 911: gate Signal line 912: Source signal line 913: Write gate signal line drive circuit 914: Erase gate signal line drive circuit 915: Source signal line drive circuit 916: Power supply 917: Current supply line 918: Switch 919: Switch 920: Switch 1001: first transistor 1002 The second transistor 1003: Gate signal line 1004: the source signal line 1005: the current supply line 1006: the electrodes of the light-emitting element 6500: substrate 6503: FPC (flexible printed circuit)
6504: Printed wiring board (PWB)
6511: Pixel portion 6512: Source signal line drive circuit 6513: Write gate signal line drive circuit 6514: Erase gate signal line drive circuit 9101: Main body 9102: Display portion 9201: Main body 9202: Display portion 9301: Main body 9302: Display Unit 9401: main body 9402: display unit 9501: main body 9502: display unit 9701: display unit 9702: display unit

Claims (2)

A first electrode functioning as an anode and made of ITO;
An electroluminescent layer in contact with the first electrode;
A second electrode in contact with the electroluminescent layer, functioning as a cathode and made of ITO;
A first stress relaxation layer made of silicon nitride oxide in contact with the second electrode;
A passivation film made of silicon nitride in contact with the first stress relaxation layer;
A second stress relaxation layer made of silicon nitride oxide in contact with the passivation film;
A light-emitting device comprising: a low-refractive-index layer that is in contact with the second stress relaxation layer and includes a stacked layer of MgF ₂ and LiF. In claim 1 ,
The light emitting device has a lighting function.

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