JP2009158140A - ELECTROLUMINESCENT ELEMENT, DISPLAY DEVICE USING SAME, AND LIGHTING DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroluminescent element capable of expanding chromaticity reproducing range, and to provide a display and an illumination device which use the same. <P>SOLUTION: A metal electrode (lower electrode; counter electrode) 18, a first insulating layer 16, juxtaposed light-emitting layers (R, G, B) 14, a multi-layered interference filter constituted of a second insulating layer (multi-layered interference film) 12, and the upper part transparent electrode 10 (constituted by juxtaposing electrodes for red light, green light and blue light to respectively extract red light, green light, blue light) are laminated on an insulating substrate 20 in this order, and the EL element is formed. Light is emitted from the upper part transparent electrode without through the substrate 20. This EL element is formed on the substrate together with a driving circuit in a matrix shape, and the display device and the illumination device are formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electroluminescence element, a display device using the same, and a lighting device.

  An electroluminescence (hereinafter referred to as EL) element is a light-emitting element utilizing a light-emitting phenomenon generated by applying an electric field to a light-emitting layer. An organic EL element using an organic material as a light-emitting layer and an inorganic material as a light-emitting layer. There are inorganic EL elements to be used.

  Since a display device using an EL element uses a self-luminous element, a backlight is not required, visibility is good, response speed is fast, and a thin, large screen, light weight, low power consumption, and the like are possible. As a product, it is being actively developed and is considered to be applied to display devices used in various electronic devices such as mobile phones, personal computers and game machines, as well as lighting devices for various purposes such as color illumination and light sources for color decoration. Has been partly put into practical use. An inorganic EL element is a completely solid device and has excellent durability and is expected to be used in a wide range of fields. High-quality, high-performance display devices are required for accurate color reproduction and display of images such as photographs and movies, telegraphic images for telemedicine and videophones, paintings, and printed materials. In order to improve the color gamut, development research has been conducted on the optimization of the structure and driving method of display elements.

  In order to realize a display device that enables full-color display, a light emitting layer that emits red light, green light, and blue light is required, but the development of blue light emitting materials for inorganic EL elements has been delayed. Recently, high-luminance blue light-emitting materials have been developed, and research and development of full-color display devices has become active, and practical application is expected.

  Patent Document 1 entitled “Optical Interference EL Element” has the following description.

  FIG. 10 is a first diagram described in Patent Document 1, and is an enlarged schematic end view of an optical interference EL element having a low reflectivity.

  FIG. 10 shows an optical interference EL element having a low reflectance as a whole by reference numeral 101. This EL element is composed of a) a front electrode electro-optical member 102 which is composed of two layers 104 and 106 and transmits EL light, and b) is located behind the front electrode electro-optical member 102 and is composed of a single layer. A counter electrode electro-optical member 108; c) an EL electro-optical member 110 having a single layer between the front electrode electro-optical member 102 and the counter electrode electro-optical member 108; and d) the electro-optical member 102. , 108, 110 and an optical member (in this embodiment, optical members 112, 114, 116, 118) that interface with at least one of the optical members 112, 114, 116, 118. Each comprises at least one optical interference film 120, 122, 124, 126 that is transparent to ambient light, so that the spectral reflectance of the EL element is Depending on the thickness and material of the optical interference films 120, 122, 124, 126 selected according to the thickness and material of the academic members 102, 108, 110, the result is, for example, that of a person viewing in the y direction or the z direction The reflectance of the surrounding light x toward the EL element 101 is determined based on the optical interference of light partially reflected at the interfaces of the optical interference films 120, 122, 124, and 126, and the electro-optical member 102, The EL element is reduced by a combination with optical interference of light partially reflected at the interface between the layers 108 and 110.

  In this embodiment, the electro-optic members 102, 108, 110 and the optical members 112, 114, 116, 118 are coated on a glass substrate 128. The layers 104 and 106 of the front electrode electro-optical member 2 may be transparent layers made of indium tin oxide (ITO) and gold. The counter electrode electro-optical member 8 may be made of aluminum. The EL electro-optical member 10 may be ZnS: Mn.

  In some embodiments of the present invention, at least one of the optical members 112, 114, 116, 118 is at least another additional film 130, 132, 134 that is partially absorbing with respect to visible light. 136, and partially absorbs the spectral reflectance and spectral absorptance of the EL element 101 and the substantially transparent films 120, 122, 124, 126 of the optical members 112, 114, 116, 118 and the light. The thickness and material of the films 130, 132, 134, and 136 are changed by combining the thickness and material of each layer of the electro-optic members 102, 108, and 110. As a result, for example, the reflectance of the ambient light traveling toward the person viewing in the X direction or the Z direction is the reflectivity of the light caused by the optical interference films 130, 132, 134, and 136 that partially absorb the light. Further reduction by optical interference absorption.

  In order to stabilize the EL electro-optical member 110 against dielectric breakdown, the EL element 101 may further include the following member. That is, a) a first dielectric electro-optical member 138 that is located between the front electrode electro-optical member 2 and the EL electro-optical member 110 and includes at least one layer (two layers 140 and 142 in this embodiment). And b) a second dielectric electro-optic member 144 between the counter electrode electro-optic member 108 and the EL electro-optic member 110 and comprising at least one layer (two layers 146 and 148 in the embodiment). C) In addition, at least one of the optical members 112, 114, 116, 118, 150, 152 may be provided on at least one of the electro-optical members 102, 108, 110, 138, 144. That is, when the first dielectric electro-optical member 138 and the second dielectric electro-optical member 144 are provided, the optical device includes the films 154 and 156, and the films 158 and 160 as necessary. At least one of the members 150 and 152 may be provided. Films 154 and 156 are substantially transparent, and films 158 and 160 are partially absorbing with respect to visible light.

  Patent Document 2 entitled “Thin Film Electro-Luminescence Device Including Optical Interference Filter” includes the following description.

  The invention of Patent Document 2 is configured so that a voltage is applied to a phosphor layer or a structure of a phosphor layer and a dielectric layer by an electrode layer having light transmittance and a light reflecting electrode layer, and the structure A multilayer optical interference filter that selectively transmits an arbitrary wavelength λ of the emission wavelength emitted from the phosphor layer is provided on the light extraction side in the body, and the dielectric film 1 having a low refractive index is provided in the structure. And dielectric film 2 having a high refractive index are alternately laminated in the order of λ / 4 = film thickness / refractive index in order of two or more layers of dielectric film 2 and dielectric film 1, and the refractive index is higher than that of dielectric film 1. Are laminated in accordance with the formula: λ / 2 · N (N is an integer of 1 or more) = film thickness / refractive index, and dielectric film 3 is further laminated to λ / 4 · positive number = film thickness / refractive. A structure including an optical interference filter characterized in that the dielectric film 3 is laminated in accordance with the rate equation.

FIG. 11 is a first diagram described in Patent Document 2, and is a cross-sectional view of the basic configuration of a thin film electroluminescent device.
A transparent electrode 202 is formed on a glass substrate 201, and a first dielectric layer (a) 204a having a refractive index n ₁ with respect to an emission wavelength of about 2.4 and a dielectric constant ε ₁ film thickness d ₁ is formed thereon. Form a film. Next, an optical thin film (for example, MgF ₂ (n ₁ = 1.38), SiO ₂ (n ₁ = 1.52)) having a refractive index n ₂ of about 1.5 is formed thereon with a film thickness d ₂ . The first dielectric layer (b) 204b is formed, and the same dielectric thin film as the first dielectric layer (a) is sequentially laminated as the first dielectric layer (c) 204c, and the film is again formed with the refractive index n ₂ . A first dielectric layer (d) 204d having a thickness d ₂ is sequentially laminated, and a phosphor layer 205 having a refractive index n ₃ of about 2.4 and a film thickness d ₃ is further formed thereon, and a refractive index n A dielectric thin film having a film thickness d ₄ of about 2.4 ± 0.2, in which the value of ₄ is similar to n ₃ , is formed as the second dielectric layer 206, and the back electrode 207 serving as a reflector layer and an electrode layer is formed. Form. Here, the first dielectric layers (a), (b), (c), (d), the phosphor layers, and the refractive indexes n ₁ , n ₂ , n ₃ with respect to the emission wavelength λ ₀ of the second dielectric layer, n ₄ was measured by an ellipsometer. Furthermore, according to the film thickness d ₁ of the dielectric layer, d _2, d ₄ and the phosphor layer thickness d ₃ is the design method of the multilayer optical interference _{filter, n i · d i = λ} 0/4 (i _{= 1,2), n 3 · d} 3 = λ 0/2 · n, n 4 · d 4 = λ 0/2 · n (n is a positive number (1,2,3 ...)) becomes equation satisfaction Was decided to be. That is, an EL element having both electroluminescence and a light interference multilayer filter is formed.

  The title of “multicolor light emitting element and its substrate” includes the following description.

  An object of the invention of Patent Document 3 is to provide an organic light emitting device having improved spectral width and light emission characteristics. The invention of Patent Document 3 that solves this problem is as follows.

  First, a minute optical resonator is composed of a light emitting layer made of an organic thin film having a light emitting function and reflecting mirrors formed on both sides of the light emitting layer, and the minute optical resonator is optically coupled between the reflecting mirrors. A multi-color light emitting element having at least two pixels having different distances.

  Second, a multicolor light emitting device in which a translucent reflective layer, a transparent conductive layer, a light emitting layer composed of an organic thin film, and an electrode are sequentially formed on a transparent substrate, and an optical element between the translucent reflective layer and the electrode. A multicolor light-emitting element includes a micro optical resonator having at least two pixels having different distances.

  Third, a multicolor light emitting device in which a translucent reflective layer, a transparent conductive layer, a light emitting layer made of an organic thin film, and an electrode are sequentially formed on a transparent substrate, and the configuration is between the translucent reflective layer and the electrode. A multicolor light-emitting element that functions as a micro-optical resonator and extracts a plurality of lights having different emission spectra from elements on the same substrate.

  Fourth, the transparent substrate has a translucent reflective layer, a transparent conductive layer is disposed on the translucent reflective layer, and a light emitting layer made of an organic thin film is provided on the transparent conductive layer. The translucent reflective layer has a reflective function of transmitting part of the light emitted from the light emitting layer to the transparent substrate side and reflecting part of the emitted light to the light emitting layer side. The translucent reflective layer functions as an optical resonator with the electrode on the back surface of the light emitting layer, and is configured so that the optical distance between the translucent reflective layer and the electrode is different. It is in the color light emitting element.

  Fifth, a transparent substrate has a translucent reflective layer, a transparent conductive layer is disposed on the translucent reflective layer, and a hole injection layer and a light emitting layer made of an organic thin film are provided on the transparent conductive layer. The semi-transparent reflective layer transmits part of the light emitted from the light emitting layer to the transparent substrate and reflects part of the emitted light to the light emitting layer. It has a reflection function, and the semitransparent reflection layer acts as an optical resonator with the electrode on the back side of the light emitting layer, and is configured so that the optical distance between the translucent reflection layer and the electrode is different. It is in the featured multicolor light emitting element.

Note that various materials have been studied as light-emitting materials used for EL devices. For example, Non-Patent Document 1 describes a typical EL spectrum of an EL device using BaAl ₂ S ₄ : Eu. Non-Patent Document 2 describes an EL spectrum of ZnS / Mn, Ag.

Japanese Patent No. 2529741 (page 5, left column, line 30 to page 6, left column, line 14, FIG. 1) Japanese Patent No. 2689661 (page 2, right column, line 20 to page 3, left column, line 24, Fig. 1) Japanese Patent No. 2797883 (paragraphs 0005 to 0012, FIG. 1) N. Miura et al, “High-Luminance Blue-Emitting BaAl2S4: Eu Thin-Film Electroluminescent Device”, Jpn. J. Appl. Phys., Vol.38 (1999) L1291-L1292 (Fig. 3) A. N. Krasnov et al, “Increased luminance of ZnS / Mn thin-film electroluminescent displays due to Ag Co-doping”, Thin Solid Films 467 (2004) 247-252 (Fig. 7)

  The inorganic EL element has been delayed until full color because there was no high-luminance blue material until recently, and it has been said that the road to practical use is far away. However, the barium thioaluminate described in Non-Patent Document 1 is used as a base material. The high-luminance blue light-emitting material mentioned above has opened the way to its practical application.

  It is an inorganic EL element that has reached the situation where light emitting materials of three colors of R (red), G (green), and B (blue) are available, but the chromaticity reproduction range, which is a characteristic required for modern flat displays. From the viewpoint of expanding the color gamut characteristics and improving the color gamut characteristics (improving the color purity), the transition between the levels giving the emission center wavelength of the light emitting material, the light emitting component due to other levels, and the broadening of the light emitting material Due to the light emission spectrum, there is a problem that the chromaticity reproduction range is narrowed (color purity is lowered) due to the emission wavelength components other than the emission center wavelength. Since light emitted from the light emitting layer of the organic EL element generally gives a broad emission spectrum, there is a problem similar to the above. Usually, as in the case of the orientation EL element, each of R, G, and B Since the color filter is provided for the light emitting layer, the element structure is complicated and the manufacturing process is complicated.

  In order to represent the chromaticity reproduction range, generally, an xy chromaticity diagram defined by CIE93 defined by the International Commission on Illumination (CIE) is used. The chromaticity reproduction range is represented by an area inside a triangle displayed when the color coordinates of the three primary colors R, G, and B are plotted on the CIExy chromaticity diagram. For example, NTSC (National Television System) color coordinates (High-vision (high-definition television broadcasting; HDTV) chromaticity coordinates), R (0.67, 0.33), G (0.21, 0.71), B (0.14, 0.08) ) Is expressed as “color reproducibility is 70% NTSC ratio” and is said to be 70% NTSC ratio in CRT.

  Enlarging the chromaticity reproduction range and widening the color gamut (enhancement of wide color gamut characteristics) is also related to the structure of the display element, and the element needs to be improved.

The inorganic EL light emitting element is expected to be a full-color display device due to BaAl ₂ S ₄ : Eu that emits blue light with high luminance described in Non-Patent Document 1, but is inorganic using this BaAl ₂ S ₄ : Eu. The blue light emission by the EL element is a relatively broad light emission because it cannot obtain a discrete light emission with a narrow half-value width like an LED or the like. In addition, ZnS: Tb in the practical range showing green light emission has a very strong and sharp peak near 545 nm corresponding to the transition of Tb from ⁵ D _{4 to} ⁷ F ₅ . Emission peaks involving ⁷ F ₆ , ⁷ F ₄ , and ⁷ F ₃ are also observed in the vicinity of 488 nm, 588 nm, and 620 nm, respectively. Such light emission is a factor that narrows the chromaticity reproduction range (decreases the color purity).

  In addition, for the purpose of expanding the chromaticity reproduction range (improving color purity) and increasing luminous efficiency, Patent Document 2 describes a thin film electroluminescent device having a structure including a Fabry-Perot interference filter. In order to configure a device that enables full color display based on this structure, an R pixel that emits red light (R), a G pixel that emits green light (G), blue light ( It is necessary to design an interference filter for each of the B pixels that radiate B).

  The present invention has been made to solve the above-described problems, and an object thereof is to expand an chromaticity reproduction range and improve a wide color gamut characteristic, and to use the electroluminescence element. Another object of the present invention is to provide a display device and a lighting device.

  That is, the present invention provides a red light emitting layer that emits red light, a green light emitting layer that emits green light, a blue light emitting layer that emits blue light, and a red light emitting layer that is provided to face the red light emitting layer. A red light electrode to be emitted, a green light electrode provided to face the green light emitting layer to emit the green light, and a blue light electrode provided to face the blue light emitting layer to emit the blue light And a counter electrode (a first electrode to be described later) provided opposite to the red light electrode, the green light electrode, and the blue light electrode and sandwiching the red light emitting layer, the green light emitting layer, and the blue light emitting layer. 18 in the first embodiment, 30 in the second embodiment to be described later), and layers having different refractive indexes alternately provided in common to the red light emitting layer, the green light emitting layer, and the blue light emitting layer. Multi-layer interference filter ( 12 in the first embodiment described above, 42 in the second embodiment described later), the red light emitting layer, the green light emitting layer and the blue light emitting layer are juxtaposed, and the red light electrode, The present invention relates to an electroluminescence element device in which the green light electrode and the blue light electrode are juxtaposed.

  The present invention also provides a white light-emitting layer that emits white light, a red light electrode that is provided to face the white light-emitting layer and emits red light, and a green light that is provided to face the white light-emitting layer. A green light electrode to be emitted, a blue light electrode that is provided facing the white light emitting layer and emits blue light, a red light electrode, the green light electrode, and the blue light electrode. A counter electrode (18 in the first embodiment to be described later, 30 in the second embodiment to be described later) provided opposite to the white light emitting layer and a different refractive index provided opposite to the white light emitting layer. A multilayer interference filter (12 in the first embodiment to be described later, 42 in the second embodiment to be described later), and the red light electrode and the green light. And the blue light electrode are juxtaposed Those of the electroluminescent device.

  The present invention also relates to a display device in which the above-described electroluminescent elements are arranged in a two-dimensional matrix.

  The present invention also relates to a lighting device in which the above-described electroluminescent elements are arranged in a two-dimensional matrix.

  According to the electroluminescent element of the present invention, the multilayer interference filter is provided in common so as to face the red light emitting layer, the green light emitting layer, and the blue light emitting layer, and the layers having different refractive indexes are alternately laminated. Therefore, the red light, the green light, and the blue light can be produced as light having a wavelength distribution with a narrowed half-value width as red light in the electroluminescence element. The R pixel that emits (R), the G pixel that emits green light (G), and the B pixel that emits blue light (B) are emitted, respectively, to expand the chromaticity reproduction range and improve the wide color gamut characteristics. An electroluminescent element that can be realized can be provided.

  In addition, according to the electroluminescent element of the present invention, since the multilayered interference filter is provided so as to face the white light emitting layer and in which layers having different refractive indexes are alternately laminated, the element is manufactured with fewer steps. The red light, the green light, and the blue light can emit R light that emits red light (R) in the electroluminescence element as light having a wavelength distribution with a narrowed half-value width, green, Provided is an electroluminescence element that is emitted from a G pixel that emits light (G) and a B pixel that emits blue light (B), respectively, and can expand the chromaticity reproduction range and improve wide color gamut characteristics. be able to.

  Further, according to the display device of the present invention, since the electroluminescence element is used, a display device capable of expanding the chromaticity reproduction range and improving the wide color gamut characteristics can be provided.

  Moreover, according to the illuminating device of the present invention, since the electroluminescence element is used, it is possible to provide an illuminating device capable of expanding the chromaticity reproduction range and improving the wide color gamut characteristics.

  In the electroluminescence device of the present invention, the multilayer interference filter is composed of a high refractive index layer and a low refractive index layer, and has a wavelength λ of any one of emission center wavelengths of the red light, the green light, and the blue light. It is preferable to include the high refractive index layer and the low refractive index layer having an optical film thickness that is an integral multiple of 1/4. According to such a configuration, a mirror layer having high light reflection and low light absorption of the multilayer interference filter can be formed by the configuration including the high refractive index layer and the low refractive index layer. Here, the optical film thickness of the film A is defined by (physical thickness d of the film A) × (refractive index n of the film A) = d × n.

The wavelength λ is the emission center wavelength λ _g of the green light, and the high refractive index layer and the low refractive index layer having an optical film thickness that is an integral multiple of λ _g / 4 are represented by H and L, respectively. , M is a positive integer indicating repetition of a pair of H and L, and a and b are positive numbers, the multilayer interference filter is (HL) ^m H (aL) (bH) (aL) It is preferable that the chromaticity points of the red light, the green light, and the blue light emitted by H (LH) ^m and adjusted are adjusted by a and b. According to such a configuration, the red light, the green light, and the blue light are light having a wavelength distribution with a narrowed half-value width, that is, red light in the electroluminescence element as narrow-band light. The light is emitted from the R pixel that emits light (R), the G pixel that emits green light (G), and the B pixel that emits blue light (B), and the chromaticity reproduction range is expanded to improve wide color gamut characteristics. Can be achieved.

  The multilayer film interference filter is provided between the red light electrode, the green light electrode, and the blue light electrode, and the red light emitting layer, the green light emitting layer, and the blue light emitting layer. It is good to do. With such a configuration, the multilayer interference filter is brought into contact with the red light electrode, the green light electrode, and the blue light electrode, and in contact with the red light emitting layer, the green light emitting layer, and the blue light emitting layer. Therefore, the multilayer interference filter can perform a filter operation with reduced light loss.

  The multilayer interference filter may be provided between the red light electrode, the green light electrode, the blue light electrode, and the white light emitting layer. With this configuration, the multilayer interference filter is provided in contact with the red light electrode, the green light electrode, and the blue light electrode and in contact with the white light emitting layer. Can perform a filter operation with reduced light loss.

  The red light has an optical film thickness that is an integral multiple of one half of the emission center wavelength of the red light, is opposed to the red light electrode, and is disposed between the red light emitting layer and the counter electrode. An insulating layer (16 in the first embodiment to be described later), an optical film thickness that is an integral multiple of one-half the emission center wavelength of the green light, facing the green light electrode, and the green light An insulating layer for green light (16 in the first embodiment described later) disposed between the light emitting layer and the counter electrode, and an optical film thickness that is an integral multiple of one half of the emission center wavelength of the blue light. A blue light insulating layer (16 in the first embodiment to be described later) disposed between the blue light emitting layer and the counter electrode so as to face the blue light electrode, and the red light The insulating layer for green, the insulating layer for green light, and the insulating layer for blue light are preferably juxtaposed. According to such a configuration, the influence of the interference on the light emitted toward the counter electrode is suppressed by the red light insulating layer, the green light insulating layer, and the blue light insulating layer. can do.

  The red light has an optical film thickness that is an integral multiple of one-half the emission center wavelength of the red light, and is opposed to the red light electrode and is disposed between the white light emitting layer and the counter electrode. An insulating layer (16 in the first embodiment to be described later), an optical film thickness that is an integral multiple of one-half the emission center wavelength of the green light, facing the green light electrode, and the white An insulating layer for green light (16 in the first embodiment described later) disposed between the light emitting layer and the counter electrode, and an optical film thickness that is an integral multiple of one half of the emission center wavelength of the blue light. A blue light insulating layer (16 in a first embodiment to be described later) disposed between the white light emitting layer and the counter electrode so as to face the blue light electrode, and the red light The insulating layer for green, the insulating layer for green light, and the insulating layer for blue light are preferably juxtaposed. According to such a configuration, the influence of the interference on the light emitted toward the counter electrode is suppressed by the red light insulating layer, the green light insulating layer, and the blue light insulating layer. can do.

  The red light emitting layer has an optical film thickness that is an integral multiple of a half of the emission center wavelength of the red light, and the green light emission layer is an integer multiple of a half of the emission center wavelength of the green light. It is preferable that the blue light emitting layer has an optical film thickness that is an integral multiple of a half of the emission center wavelength of the blue light. According to such a configuration, the influence of interference on the light emitted toward the counter electrode can be suppressed by the red light emitting layer, the green light emitting layer, and the blue light emitting layer.

  The red light emitting electrode has an optical film thickness that is an integral multiple of one half of the emission center wavelength of the red light, and the green light emission electrode is one half of the emission center wavelength of the green light. It is preferable that the blue light emitting electrode has an optical film thickness that is an integral multiple of one half of the emission center wavelength of the blue light. According to such a configuration, the influence of interference can be suppressed by the red light emitting layer, the green light emitting layer, and the blue light emitting layer.

  In addition, the counter electrode is common to these electrodes by facing the red light electrode, the green light electrode, and the blue light electrode across the red light emitting layer, the green light emitting layer, and the blue light emitting layer. It is preferable that the common electrode is provided in the structure. According to such a configuration, the common electrode can be formed by a small number of steps.

  The counter electrode is a common electrode provided in common to the red light electrode, the green light electrode, and the blue light electrode across the white light emitting layer. It is good to do. According to such a configuration, the common electrode can be formed by a small number of steps.

  Further, it is preferable that a space between two phosphor layers of the red light emitting layer, the green light emitting layer, and the blue light emitting layer is filled with an insulator. With such a configuration, the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer are used as the insulator by using a material having a function of separating and independently separating phosphor layers that are electrically and optically adjacent to each other. The phosphor layers adjacent to each other can be electrically separated and independent, and optical crosstalk can be suppressed. In the electroluminescence element, R pixels that emit red light (R) and green light (G) are emitted. It is possible to ensure an independent light emitting action in the G pixel and the B pixel that emits blue light (B).

  The counter electrode, the juxtaposed red light emitting layer, the green light emitting layer and the blue light emitting layer, the multilayer interference filter, the juxtaposed red light electrode, the green light electrode and the blue light electrode However, it is preferable that elements are formed by stacking on the substrate in this order, and light is emitted from the side of the substrate where the elements are formed. With this configuration, light is emitted from the side of the substrate on which the element is formed, that is, the red light electrode, the green light electrode, and the blue light electrode, so the aperture ratio of the electrochromic element (Ratio of the area where light is emitted with respect to the area of the EL element) can be increased, and the luminance of the EL element can be improved.

  Further, the counter electrode, the white light emitting layer, the multilayer interference filter, the juxtaposed red light electrode, the green light electrode, and the blue light electrode are laminated on the substrate in this order to form an element, It is preferable that light is emitted from the side of the substrate where the element is formed. With this configuration, light is emitted from the side of the substrate on which the element is formed, that is, the red light electrode, the green light electrode, and the blue light electrode, so the aperture ratio of the electrochromic element (Ratio of the area where light is emitted with respect to the area of the EL element) can be increased, and the luminance of the EL element can be improved.

  The multilayer interference filter may be configured to face the red light emitting layer, the green light emitting layer, and the blue light emitting layer with the counter electrode interposed therebetween. With such a configuration, the multilayer interference filter is provided so as to face the red light emitting layer, the green light emitting layer, and the blue light emitting layer and in contact with the counter electrode from which light is emitted. The interference filter can perform a filter operation with reduced light loss.

  The multilayer interference filter may be configured to face the white light emitting layer and sandwich the counter electrode. With such a configuration, the multilayer interference filter is provided so as to face the white light emitting layer and to contact the counter electrode from which light is emitted. Therefore, the multilayer interference filter reduces light loss. Can be filtered.

  Further, the juxtaposed red light electrode, the green light electrode and the blue light electrode, the juxtaposed red light emitting layer, the green light emitting layer and the blue light emitting layer, the counter electrode, and the multilayer interference filter Are arranged in this order on the substrate to form an element, and light is emitted from the side of the substrate where the element is formed. With such a configuration, since light is emitted from the side of the substrate where the element is formed, that is, the counter electrode, the aperture ratio of the electrochromic element (the ratio of the area where light is emitted to the area of the EL element) ) Can be increased, and the luminance of the EL element can be improved.

  The red light electrode, the green light electrode, the blue light electrode, the white light emitting layer, the counter electrode, and the multilayer interference filter arranged in parallel are stacked on the substrate in this order to form an element. It is preferable that light is emitted from the side of the substrate where the element is formed. With such a configuration, since light is emitted from the side of the substrate where the element is formed, that is, the counter electrode, the aperture ratio of the electrochromic element (the ratio of the area where light is emitted to the area of the EL element) ) Can be increased, and the luminance of the EL element can be improved.

  Further, the white phosphor layer includes a layer formed of a material capable of emitting the red light, the green light, and the blue light from a single material, the red light emitting layer, the green light emitting layer, and the blue light emitting layer. It can be configured by any one of a layer formed by stacking three layers, a material that emits red light, a material that emits green light, and a material that emits blue light. According to such a configuration, the white phosphor layer can be formed by fewer steps.

  The EL device according to the present invention is a multilayer film interference in which layers having different refractive indexes of high and low are alternately laminated to transmit light in the red (R), green (G), and blue (B) wavelength bands. The filter is formed by laminating the juxtaposed red light emitting layer, green light emitting layer and blue light emitting layer, or by laminating on the white light emitting layer, and the EL element emits red light (R) R pixel, green light The pixel is composed of a G pixel that emits (G) and a B pixel that emits blue light (B), and each of the R, G, and B pixels is formed by an EL sub-element corresponding thereto. A plurality of EL elements are arranged in a two-dimensional matrix on the same substrate to realize a surface emitting device that realizes full color. This surface light emitting device is configured as a display device or a lighting device.

  A display device and a lighting device which are formed using a EL element on a substrate are driven by a simple matrix type (passive matrix type) or active matrix type driving circuit formed on the substrate.

  For example, in an active matrix display device, an inorganic or organic EL element is formed on a substrate (TFT substrate) on which a thin film transistor (TFT) is previously formed in a state of being connected to the TFT, and serves as an anode or a cathode. The upper electrode formed with the opposite polarity to the lower electrode formed by the transparent conductive film is used to extract the light emitted in the device from the upper electrode side and away from the substrate. By using a so-called top emission type EL element that emits light from the electrode side, the aperture ratio of the electrochromic element (ratio of the area where light is emitted to the area of the EL element) can be increased. Brightness can be improved.

  In the first configuration of the EL element of the present invention, a red light emitting layer (a layer emitting red light), a green light emitting layer (a layer emitting green light), and a blue light emitting layer (a layer emitting blue light) are juxtaposed. Opposite to the red light emitting layer, the green light emitting layer and the blue light emitting layer, a red light electrode (a layer for emitting and extracting red light), a green light electrode (a layer for emitting and extracting green light), and A blue light electrode (a layer for emitting and extracting blue light) is juxtaposed, and a red light emitting layer, a green light emitting layer, and a blue light emitting layer are arranged opposite to the red light electrode, the green light electrode, and the blue light electrode. A multilayer interference filter in which counter electrodes are provided and sandwiched alternately with layers having different refractive indexes is provided in common to the red light emitting layer, the green light emitting layer, and the blue light emitting layer.

  In the second configuration of the EL element of the present invention, the red light emitting layer, the green light emitting layer, and the blue light emitting layer are replaced with a white phosphor layer that emits red light, green light, and blue light. The white phosphor layer is a layer formed of a material capable of emitting red light, green light and blue light from a single material, a layer formed by laminating a red light emitting layer, a green light emitting layer and a blue light emitting layer, red It can be configured by any one of a mixed layer of three materials: a light emitting material, a green light emitting material, and a blue light emitting material.

In the first and second configurations, the multilayer interference filter is composed of a high refractive index layer and a low refractive index layer, and is a quarter of the wavelength λ of one of the emission center wavelengths of red light, green light, and blue light. A high refractive index layer and a low refractive index layer having an optical film thickness that is an integral multiple of 1 are included. As the wavelength λ, for example, an emission center wavelength λ _g of green light is selected, and a high refractive index layer and a low refractive index layer having an optical film thickness that is an integral multiple of λ _g / 4 are represented by H and L, respectively. , M is a positive integer indicating the repetition of a pair of layers H and L, and a and b are positive numbers, the multilayer interference filter is (HL) ^m H (aL) (bH) (aL) H (HL) It is represented by ^m , and the chromaticity points of red light, green light and blue light emitted from the EL element can be adjusted by a and b. As the wavelength λ, the emission center wavelength of green light or blue light can be selected. By selecting λ _g that is the center of the stop band as the wavelength λ, the bandwidth can be designed to be narrow, that is, the total number of films required for constituting the multilayer interference filter can be reduced. can get.

  m, a, and b, for example, in consideration of the insulation resistance of the multilayer interference film, so that the color reproduction range reproducible by red light emission, green light emission, and blue light emission emitted from the EL element is expanded as much as possible. It can be determined by simulation or experimentally.

  In the first and second configurations, the red light emitting layer has an optical film thickness (red optical film thickness) that is an integral multiple of one half of the light emission center wavelength of red light, and the green light emission layer has a green light emission center. It has an optical film thickness (green optical film thickness) that is an integral multiple of one-half wavelength, and the blue light-emitting layer has an optical film thickness (blue optical film thickness) that is an integral multiple of one-half the emission center wavelength of blue light. ). When the red light emitting layer, the green light emitting layer, and the blue light emitting layer are replaced with the above white phosphor layer, the white fluorescent light at the position facing the red light electrode, the green light electrode, and the blue light electrode, respectively. A body layer is comprised so that it may become said red optical film thickness, green optical film thickness, and blue optical film thickness.

  In the first and second configurations, the red light emitting electrode has an optical film thickness that is an integral multiple of one half of the emission center wavelength of red light, and the green emission electrode is 2 minutes of the emission center wavelength of green light. It is assumed that the blue light emitting electrode has an optical film thickness that is an integral multiple of one half of the emission center wavelength of blue light.

  In the first and second configurations, the counter electrode has a red light emitting layer, a green light emitting layer, and a blue light emitting layer, or the white light emitting layer is sandwiched between the red light electrode, the green light electrode, and the blue light. It is formed as a common electrode provided in common with these electrodes so as to face the light electrode.

  In the first and second configurations, the phosphor layers of the red light emitting layer, the green light emitting layer, and the blue light emitting layer are filled with an insulator having a function of separating and independently separating the phosphor layers that are electrically and optically adjacent to each other. The phosphor layers adjacent to each other of the red light emitting layer, the green light emitting layer, and the blue light emitting layer are electrically separated and independent, optical crosstalk between adjacent phosphor layers is suppressed, and red light (R ) Emitting green light (G), G pixel emitting green light (G), and B pixel emitting blue light (B) perform independent light emitting actions.

  In the case where the EL element is configured as an inorganic EL element, the following configuration is assumed in the first and second configurations.

  The multilayer interference filter includes a red light electrode, a green light electrode and a blue light electrode and a red light emitting layer, the green light emitting layer and the blue light emitting layer, or a red light electrode, a green light electrode and It arrange | positions between the electrode for blue lights, and a white light emitting layer.

  The insulating layer for red light has an optical film thickness that is an integral multiple of a half of the emission center wavelength of red light, and is disposed between the red light emitting layer and the counter electrode so as to face the red light electrode. The insulating layer has an optical film thickness that is an integral multiple of a half of the emission center wavelength of green light, and is disposed between the green light emitting layer and the counter electrode so as to face the green light electrode, The layer has an optical film thickness that is an integral multiple of a half of the emission center wavelength of blue light, and is disposed between the blue light emitting layer and the counter electrode so as to face the blue light electrode, The green light insulating layer and the blue light insulating layer are juxtaposed. In this configuration, the red light emitting layer, the green light emitting layer, and the blue light emitting layer can be replaced with the white light emitting layer.

  A counter electrode; a juxtaposed red light emitting layer, a green light emitting layer and a blue light emitting layer; a multilayer interference filter, a juxtaposed red light electrode, a green light electrode and a blue light electrode; EL elements are formed, or a counter electrode; a white light emitting layer; a multilayer interference filter; a red light electrode, a green light electrode, and a blue light electrode, which are juxtaposed, are laminated on the substrate in this order. An EL element is formed, and light is emitted from the side where the EL element is formed (that is, the counter electrode side) without passing through the substrate.

  In the case where the EL element is configured as an inorganic EL element, the following configuration is assumed in the first and second configurations.

  The multilayer interference filter is disposed to face the red light emitting layer, the green light emitting layer, and the blue light emitting layer, or to face the white light emitting layer, with the counter electrode interposed therebetween.

  A juxtaposed red light electrode, green light electrode and blue light electrode; juxtaposed red light emitting layer, green light emitting layer and blue light emitting layer; counter electrode; multi-layer interference filter; EL elements are formed or juxtaposed electrodes for red light, green light and blue light; white light emitting layer; counter electrode; multilayer interference filter; are laminated on the substrate in this order. The EL element is formed, and light is emitted from the side where the EL element is formed without passing through the substrate (that is, the red light electrode, the green light electrode, and the blue light electrode side). To do.

  The EL element according to the present invention can be used for a display unit of a mobile phone and a display unit of an electronic device such as a personal computer, and can display a color and can realize bright high display quality.

  The substrate on which the EL element is formed is not limited to a flat substrate, and can be a flexible substrate that can be bent. The EL element can be arbitrarily arranged to form various substrate shapes, and color display is possible. The present invention can be widely applied to various illumination devices such as display devices, color illumination illumination, and color decoration light sources. According to the display device and the illumination device of the present invention, a voltage is applied to the cathode and the anode to generate an electric field between them, thereby causing the light emitting layer to emit light in any one of red, green, and blue. Can do. Therefore, color display and illumination can be performed using this light emission.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

  First, components common to inorganic EL elements and organic EL elements, substrates, and multilayer interference filters will be described.

About the board:
As a substrate on which the EL element is formed, a transparent substrate such as glass, a silicon substrate, a film-like flexible substrate, or the like can be appropriately selected and used. When the driving method of the display device and lighting device configured using EL elements is an active matrix method, a TFT substrate in which a thin film transistor (TFT) is formed for each of R, G, and B pixels of each EL element is used as the substrate. Used. In this case, the R, G, and B pixels of each EL element have a structure that is driven using TFTs. In this case, in the display device and the lighting device, it is advantageous in terms of the aperture ratio of the element (pixel) to use a top emission type EL element in which light emission is extracted only from one side away from the substrate. That is, it is advantageous in that the use efficiency of EL emission is increased. Even if a pixel circuit for driving an EL element is formed on the substrate, the utilization efficiency of EL light emission is not reduced.

  In a back emission type EL device that attempts to extract light emission from the transparent substrate side such as glass, guided light that is lost by being guided through the transparent substrate is generated, and the transparent substrate is used for driving the EL device. When the pixel circuit is formed, the light extraction area is limited and the use efficiency of EL light emission is lowered.

  Note that when the EL element is a double-sided light emitting type in which light emission is extracted from both sides of the substrate, the substrate is a transparent substrate made of a light-transmitting material. The substrate on which the EL element is formed is not limited to a flat substrate, and may be a foldable flexible substrate.

About multilayer interference filters:
The multilayer interference filter is composed of a high refractive index layer and a low refractive index layer, and has an optical film thickness that is an integral multiple of one-fourth of the wavelength λ of the emission center wavelength of red light, green light, or blue light. A high refractive index layer and a low refractive index layer. As the wavelength λ, for example, an emission center wavelength λ _g of green light is selected, and a high refractive index layer and a low refractive index layer having an optical film thickness that is an integral multiple of λ _g / 4 are represented by H and L, respectively. , M is a positive integer indicating the repetition of a pair of layers H and L, and a and b are positive numbers.

The multilayer interference filter is represented by (HL) ^m H (aL) (bH) (aL) H (HL) ^m . (HL) ^m is a high refractive index layer having an optical film thickness (layer thickness) H, L is a low refractive index layer having an optical film thickness (layer thickness) L, and (HL) ^m is For example, in the case of m = 3, a laminated film of 6 layers made of HLHLHL is shown, and its total thickness is 3 × ((layer thickness H) + (layer thickness L )). The thicknesses of the layer (aL) and the layer (bH) are a × (layer thickness L) and b × (layer thickness H), respectively.

Each of the layer (HL) ^m H and the layer H (HL) ^m forms a mirror layer with high light reflection and low light absorption. The layers (aL), (bH), and (aL) are spacer layers sandwiched between the mirror layers, and match the wavelengths of red, green, and blue light for which the transmittance is to be maximized, and have chromaticity. A and b are determined so that the reproduction range is expanded as much as possible.

As described above, the multilayer interference filter represented by (HL) ^m H (aL) (bH) (aL) H (HL) ^m narrows the band of red light, green light, and blue light (m is increased). Then, the full width at half maximum of the wavelength distribution of the light extracted from the EL element can be reduced.) The chromaticity points of the red light, the green light, and the blue light emitted from the EL element are adjusted by a and b. Can do.

In addition, as a low refractive index material constituting the low refractive index layer, CaF ₂ (n = 1.23 to 1.45), LiF (n = 1.3), AlF ₃ (n = 1.38), MgF ₂ (N = 1.38), SiO ₂ (n = 1.45), LaF ₃ (n = 1.59), NdF ₃ (n = 1.61), CeF ₃ (n = 1.63), Al ₂ O ₃ (n = 1.63), MgO (n = 1.74), Y ₂ O ₃ (n = 1.87), AlN (n = 1.94), Si ₃ N ₄ (n = 1.95) ), HfO ₂ (n = 1.95), or the like can be used.

Further, as a high refractive index material constituting the high refractive index layer, ZrO ₂ (n = 2.05), ZnO (n = 2.1), Ta ₂ O ₅ (n = 2.16), CeO ₂ (n = 2.2), Nb ₂ O ₅ (n = 2.2), TiO ₂ (n = 2.30), BaTiO ₃ (n = 2.3), ZnSe (n = 2.40), Si (n = 3.4), Ge (n = 4.0), SrTiO ₃ (n = 2.41), PbTe (n = 5.67), or the like can be used.

  In the example described above, the low refractive index material and the high refractive index material are shown with the refractive index n = 2 shown in () as the boundary, but the boundary between the high and low refractive indices is arbitrary.

First Embodiment FIG. 1 is a cross-sectional view schematically showing the structure of an inorganic EL element in the first embodiment of the present invention. FIG. 1A shows three colors of R, G, and B. FIG. 1B is a cross-sectional view of an element using a white light-emitting layer.

  FIG. 1 shows a display device (or lighting device) using an inorganic EL element. FIG. 1A shows a light emitting layer 14 of three colors R, G, and B constituting one pixel in a straight line in the x direction. FIG. 1B is a cross-sectional view of one element in the x direction in a configuration in which the linear array is repeated in the y direction, and FIG. 1B illustrates the x in the configuration using the white light emitting layer 24 as the light emitting layer. 1 shows a cross-sectional view of one element in the direction.

  The EL element is composed of an R pixel that emits red light (R), a G pixel that emits green light (G), and a B pixel that emits blue light (B). A corresponding EL sub-element is formed.

  As shown in FIG. 1A, a metal electrode (lower electrode; counter electrode) 18, a first insulating layer 16, a light emitting layer (R, G, B) 14 juxtaposed, a second insulating layer (multilayer interference film) Multilayer interference filter composed of 12, upper transparent electrode 10 (red light electrode for extracting red light, green light electrode for extracting green light, and blue light electrode for extracting blue light are juxtaposed. Are stacked in this order on the electrically insulating substrate 20 to form an EL element. Since light is emitted from the upper transparent electrode 10 without passing through the substrate 20, the light extraction efficiency of the EL element can be increased, and the luminance can be improved. The EL element constitutes one pixel in the display device and one pixel in the illumination device, that is, one light source. Usually, a plurality of EL elements are arranged on the substrate 20 in a two-dimensional matrix. Hereinafter, each element constituting the inorganic EL element will be described in order from the substrate 20 side.

  The lower electrode 18 formed on the substrate (glass substrate) 20 is formed using aluminum (Al) which is a conductive material having excellent light reflectivity, and also serves as a light reflection layer (total reflection layer). It acts as an electrode for applying a voltage to the light emitting layer (R, G, B) 14 together with the (transparent electrode) 1. The lower electrode 18 is provided in common facing the light emitting layer 14 corresponding to R, G, and B. Note that the lower electrode 18 may be provided individually and independently so as to face the light emitting layers 14 corresponding to R, G, and B.

  Further, the lower electrode 18 may be formed with a single layer structure made of a metal thin film with excellent light reflectivity, or a metal thin film with excellent light reflectivity may be formed on a conductive film such as a metal with poor light reflectivity. It is good also as the formed two-layer structure. The metal thin film excellent in light reflectivity is formed using, for example, gold (Au), silver (Ag), aluminum (Al), or an alloy containing the same.

  For example, the lower electrode 18 is patterned and formed in a shape suitable for a driving method of a display device or an illumination device using an EL element. For example, when the driving method is a simple matrix type, the lower electrode 18 is formed in a stripe shape, for example. When the driving method is an active matrix type in which a TFT is provided for each EL sub-element corresponding to the R, G, and B sub-pixels, a plurality of lower electrodes 18 are arranged in the EL sub-sub (sub ) It is formed by patterning corresponding to each pixel, and is formed in a state where each is connected to the TFT provided for each EL sub (sub) pixel.

  The thickness of the first insulating layer 16 provided facing the light-emitting layer 14 corresponding to the light-emitting layer (inorganic light-emitting layer) 14R corresponding to R, G, and B formed of the above-described high refractive index material depends on the EL element. An optical film thickness that is an integral multiple of a half of the wavelength of red light to be extracted from the first light-emitting layer 14 corresponding to G is provided. An optical film thickness that is an integral multiple of one-half of the wavelength of the green light to be extracted from the first light-emitting layer 14 corresponding to B is provided. An optical film thickness that is an integral multiple of one half of the wavelength of the blue light to be extracted from the light is given. By setting it as such thickness, the influence of interference can be suppressed.

Light emitting layers (inorganic light emitting layers) 14 corresponding to R, G, and B are formed on the first insulating layer 16 facing each other. As the inorganic light emitting layer, various known inorganic materials such as EL phosphors doped with rare earth elements using ZnS, ZnSe, CdS, SrS and the like as a base material, and ternary phosphors such as BaAl ₂ S ₄ : Eu are used. It can be used, and color emission of each color is possible by applying a voltage between electrodes sandwiching the inorganic light emitting layer. The material which comprises the inorganic light emitting layer corresponding to R, G, B is illustrated below.

As a red light emitting layer, for example, ZnS: Mn, ZnS: Sm, CaS: Eu, MgCaS: Eu, MgGa ₂ O ₄ : Eu, SrSb ₂ O ₄ : Mn, SrSb ₂ O ₄ : Eu, SrSb ₂ O ₆ : Mn SrSb ₂ O ₆ : Eu or the like can be used.

For example, ZnS: Tb, CaS: Ce, ZnMgS: Mn, SrGa ₂ S ₄ : Eu, or the like can be used as the green light emitting layer.

As the blue light emitting layer, can be used. For example, ZnS: Tm, SrS: Ce , CaS: Pb, Ce 2 Ga 2 S 4: Ce, Sr 2 Ga 2 S 4: Ce, SrS: Cu, BaAl 2 S 4: can be used Eu and the like.

  In the above description, the configuration including the light emitting layer (inorganic light emitting layer) 14 corresponding to R, G, and B and the first insulating layer 16 provided individually corresponding to each of these layers has been described. An inorganic light emitting layer (white phosphor layer) may be provided in common with the first insulating layer 16.

  As shown in FIG. 1B, a white phosphor layer can be used as the inorganic light-emitting layer in place of the light-emitting layer (inorganic light-emitting layer (R, G, B)) 14 shown in FIG. The EL element having this configuration can be suitably used for a lighting device.

The white phosphor layer is a material capable of emitting red light, green light and blue light from a single material (for example, Ga _x Zr _1-x O ₃ : Eu, Tb (0.8 ≦ x ≦ 2.0)) A layer formed by laminating a red light emitting layer, a green light emitting layer and a blue light emitting layer, a material emitting red light, a material emitting green light, and a material emitting blue light. It can be constituted by any of the mixed layers. According to such a configuration, the white phosphor layer can be formed with fewer steps.

  The thickness of the inorganic light-emitting layer 14 corresponding to R gives an optical film thickness that is an integral multiple of one-half the wavelength of red light to be extracted from the EL element, and the thickness of the inorganic light-emitting layer 14 corresponding to G The thickness of the inorganic light-emitting layer 14 corresponding to B is the blue color to be extracted from the EL element. An optical film thickness that is an integral multiple of one-half of the wavelength of light is given. By setting it as such thickness, the influence of interference can be suppressed.

In the following description, ZnS: Mn is used as the red light emitting layer, BaAl ₂ S ₄ : Eu is used as the blue light emitting layer, and ZnS: Tb is used as the green light emitting layer.

The multilayer interference filter constituted by the second insulating layer (multilayer interference film) 12 uses SiO ₂ (n = 1.45) as the low refractive index material and Nb ₂ O ₅ (n = 2.2), in the above-mentioned (HL) ^m H (aL) (bH) (aL) H (HL) ^m , m = 1, a = 2.25, b = 3.1. ing. The thickness of each layer of the multilayer interference filter represented by (HL) H (2.25L) (3.1H) (2.25L) H (HL) is shown in FIG. Since the multilayer interference filter is provided in common to the light emitting layers of the light emitting layers (R, G, B) 14 arranged side by side, the productivity of the EL element can be increased.

The upper transparent electrode 10 is provided on the side from which light is extracted from the EL element, and is formed of a transparent conductive film having good light transmittance or a metal thin film having light reflectivity as well as light reflectivity, and also serves as a light reflection layer. A cavity (optical resonator) structure is formed between the metal electrode (lower electrode; counter electrode) 18 and the upper transparent electrode 10. A transparent conductive film for supplementing conductivity may be laminated on the metal thin film to form a two-layer structure. By using a transparent conductive film that is made of ITO, IZO (In-Zn-O), ZnO, AZO, tin oxide (SnO ₂ ), etc. and has good light transmission, the amount of emitted light is increased and luminance is improved. Can be achieved. The metal thin film is formed of, for example, Au, Ag, Cu, Cr, Ni, Al, Mg—Ag alloy, or the like.

  The upper transparent electrode 10 is provided individually and independently corresponding to each light emitting layer (inorganic light emitting layer) 14 corresponding to R, G, B, and the thickness of the upper transparent electrode 10 corresponding to R is EL element An optical film thickness that is an integral multiple of a half of the wavelength of red light to be extracted from the EL element is given, and the thickness of the upper transparent electrode 10 corresponding to G is 2 of the wavelength of green light to be extracted from the EL element. An optical film thickness that is an integral multiple of one-half is provided, and the thickness of the upper transparent electrode 10 corresponding to B is an optical film thickness that is an integral multiple of one-half the wavelength of the blue light to be extracted from the EL element. Shall be given. By setting it as such thickness, the influence of interference can be suppressed.

  A driving power source is connected between the upper transparent electrode 10 and the metal electrode (lower electrode; counter electrode) 18, and red (R), green (G), and blue (B) are applied by applying a voltage. Are emitted, and these are colored and emitted.

  Further, the upper transparent electrode 10 is formed in a stripe shape intersecting with the stripe of the metal electrode (lower electrode; counter electrode) 18 when the display device configured using the EL element is a simple matrix type, The portion where these are crossed and stacked is an EL element. When this display device is an active matrix type, the upper transparent electrode 10 may be formed as a continuous electrode, and is used as a common electrode for each EL element in common with the R, G, and B pixels. .

  In the upper transparent electrode 10, the light emitting layer 14, and the first insulating layer 16, the phosphor layers are electrically separated and independent between the layers corresponding to R, G, and B, and optical crosstalk is caused. In order to suppress, it is filled with an insulator 22 having a function of separating and independently separating the phosphor layers electrically and optically, and emits R pixel that emits red light (R) and green light (G). Independent light emitting action is secured in the G pixel and the B pixel that emits blue light (B). In the case where a lighting device is configured using an EL element, at least the layers corresponding to R, G, and B may be electrically separated and independent.

In the inorganic EL element having the above-described configuration, the second insulating layer 12 provided in common to the light emitting layers of the light emitting layers (R, G, B) 14 arranged side by side has (HL) ^m H (aL) ( bH) (aL) H (HL) It is constituted by a multilayer interference film represented by ^m and acts as a multilayer interference filter, narrowing the band of red light, green light and blue light (when m is increased, it is extracted from the EL element) The half-value width of the wavelength distribution of light can be made smaller.), And the chromaticity points of red light, green light and blue light emitted from the EL element can be adjusted by a and b.

  If m is increased, the wavelength distribution of light that can be extracted becomes sharper. However, the total thickness of the second insulating layer becomes too thick, and the light emission starting voltage rises, causing dielectric breakdown. Is preferably 1 to 2 (if a second insulating layer of about 1 μm is used, a voltage of about 300 V is required). As will be described later, as a result of simulation, the value of a is preferably in the range of 2 to 2.5, and if it is about 2.25, the color purity becomes high. Further, the value of b is preferably in the range of 2.7 to 3.3, and if 3.1, the chromaticity reproduction range is the widest (color purity is high). As a result, light emission from unnecessary levels of the inorganic light-emitting layer 14 can be eliminated by optical interference, the chromaticity reproduction range can be expanded (color purity can be increased), and a wide color gamut inorganic EL element can be obtained. Can be realized.

  Note that a display device and a lighting device using the above-described inorganic EL elements arranged in a matrix and formed on a substrate are driven by a simple matrix type or active matrix type driving method (not shown).

  FIG. 2 is a diagram for explaining a specific example of the structure of the inorganic EL element shown in FIG. 1A in the first embodiment of the present invention. FIG. 2A is shown in FIG. FIG. 2B is a cross-sectional view schematically showing a layer structure. FIG. 2B is a layer configuration showing the thickness and refractive index of each layer constituting the inorganic EL element shown.

  FIG. 2 (B) shows FIG. 1 (A) reflecting the thickness of each layer shown in FIG. 2 (A), and the light emitting layer (R, G, B) in FIG. 2 (B). 14 is connected, the structure corresponds to FIG. 1B reflecting the thickness of each layer shown in FIG.

As shown in FIG. 2A, the layer structure of the inorganic EL element is as follows. ZnS: Mn, ZnS: Tb, BaAl ₂ S ₄ : Eu are used as the red light emitting layer, the green light emitting layer, and the blue light emitting layer, respectively, and the refractive index of these phosphors is set to n = 2.3, so that red light, green light, The emission center wavelengths of the blue light were λ _r = 630 nm, λ _g = 545 nm, and λ _b = 455 nm. Further, the second insulating layer (multilayer interference film) 12 is formed using a high refractive index material Nb ₂ O ₅ (refractive index n = 2.2) and a low refractive index material SiO ₂ (refractive index n = 1.45). Configured. Nb ₂ O ₅ was used as the first insulating layer 16 and ITO (refractive index n = 2) was used as the upper transparent electrode 10.

  The thickness of each layer of the layer structure of the inorganic EL element shown in FIG. 2 (A) was determined as follows.

The thickness of the upper transparent electrode 10 corresponding to R, G, B is
R: (λ _r / 2) × 1/2 = 158 nm
G: (λ _g / 2) × 1/2 = 136 nm
B: (λ _b / 2) × 1/2 = 114 nm
It was.

The thickness of the light emitting layer (R, G, B) 14 corresponding to R, G, B is
R: (λ _r /2)×5/2.3=685 nm
G: (λ _g /2)×5/2.3=592 nm
B: (λ _b /2)×5/2.3=495 nm
It was.

The thickness of the first insulating layer 16 in R, G, B is
R: (λ _r /2)×1/2.2=143 nm
G: (λ _g /2)×1/2.2=124 nm
B: (λ _b /2)×1/2.2=103 nm
It was.

The layers constituting the second insulating layer (multilayer interference film) 12 are m = 1, a = 2.25, b = 3.1, and layers-1 to layer-9 (layer-5) from the glass substrate 20 side. And the thickness of layer-1 to layer-5 is
Layer-1: (λ _g /4)×1/2.2=62 nm
Layer-2: (λ _g /4)×1/1.45=94 nm
Layer-3: (λ _g /4)×1/2.2=62 nm
Layer-4: a × (λ _g /4)×1/1.45=211 nm
Layer-5: b × (λ _g /4)×1/2.2=192 nm
Layer-6: a × (λ _g /4)×1/1.45=211 nm
Layer-7: (λ _g /4)×1/2.2=62 nm
Layer-8: (λ _g /4)×1/1.45=94 nm
Layer-9: (λ _g /4)×1/2.2=62 nm
It was.

Here, the thicknesses of the layer-1 to the layer-9 constituting the second insulating layer (multilayer interference film) 12 are determined using λ _g = 545 nm, but using λ _r = 630 nm or λ _b = 455 nm. It can also be determined. The design of the interference film is such that the band spreads to the short wavelength side and the long wavelength side with the design wavelength as the center. Therefore, when the suppression band is designed around λ _r = 630 nm or λ _b = 455 nm, the bandwidth is 630 nm ± 25 nm, It is necessary to design in a wide band of about 455 nm ± 250 nm, resulting in a disadvantage that the total number of films necessary for forming the second insulating layer (multilayer interference film) 12 becomes very large.

Second Embodiment FIG. 3 is a cross-sectional view schematically showing a configuration of an organic EL element in a second embodiment of the present invention, and a display device (or lighting device) using the organic EL element. 1 element in the x direction in the configuration in which the light emitting layers 14 of three colors of R, G, and B constituting one pixel are arranged linearly in the x direction, and this linear arrangement is repeated in the y direction. FIG.

  Hereinafter, each component constituting the organic EL element will be described in order from the substrate side. However, the substrate and the multilayer interference filter have the same configuration as the inorganic EL element described in the first embodiment. The explanation will not be repeated.

  The light reflection layer (total reflection layer) 44 formed on the substrate 40 is made of a light reflective metal material such as Al, Au, Ag, or an alloy containing these elements, and the transparent insulating film 46 is formed on the light reflection layer 44. Is formed. An anode 38 is formed on the transparent insulating film 46 as a lower electrode. The lower electrode (anode 38) is formed individually and independently, facing the organic light emitting layer 34 corresponding to R, G, and B.

  Examples of the lower electrode (anode 38) include metals such as Au, Ag, Cu, Cr, Ni, Al, and Mg—Ag alloys, transparent conductive films such as ITO, IZO, and ZnO, PEDOT / PSS [poly (3, 4-ethylenedioxythiophene) / poly (4-styrenesulfonate)] and the like. Among these, it is preferable to use a material having a high work function because a hole injection barrier into the organic layer can be reduced. The lower electrode (anode 38) may have a single layer structure using the above materials or a laminated structure.

  The lower electrode (anode 38) is patterned and formed in a shape suitable for a display device using organic EL and a driving method of the illumination device. For example, when the driving method is a simple matrix type, the lower electrode (anode 38) is formed in a stripe shape, for example. When the driving method is an active matrix type having a TFT for each of R, G, and B pixels, the lower electrode (anode 38) is made to correspond to each of a plurality of arranged R, G, and B pixels. It is formed by patterning, and is formed in a state where each TFT is provided for each R, G, B pixel.

  The hole transport layer 36 is formed as a continuous layer on the lower electrode (anode 38) formed independently and facing the organic light emitting layer 34 corresponding to R, G, and B. As a material constituting the hole transport layer 36, for example, N, N′-bis (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPD), N , N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (triphenyldiamine derivative, TPD), N, N′-diphenyl-N, N′-bis [N-phenyl-N- (2-naphthyl) -4′-aminobiphenyl-4-yl] -1,1′-biphenyl-4,4′-diamine (NPTE) or the like is used. Moreover, it is not limited to these, Polyphenylene vinylene whose polymer precursor is polytetrahydrothiophenylphenylene, 1,1-bis- (4-N, N-ditolylaminophenyl) cyclohexane, etc. can also be used.

  The hole injection layer described later may also serve as the hole transport layer 36. For example, 3,4-polyethylenediosithiophene / polystyrene sulfonic acid (PEDOT / PSS), which is a polyolefin derivative, is used as the hole injection material. The hole injection layer can be formed by discharging a dispersion obtained by dispersing the organic solvent as a main solvent to a predetermined region and then drying the dispersion.

  A hole injection layer may be provided between the anode 38 and the hole transport layer 36 in contact with the hole transport layer. The hole injection layer may be, for example, copper phthalocyanine (CuPc), 4,4 ′, 4 ″ -tris (naphthylphenylamino) triphenylamine (TNATA), 4,4 ′, 4 ″ -tris [N- (3- Methylphenylphenylamino) triphenylamine (m-MTDATA)] and the like.

  Although the organic light emitting layer (R, G, B) 34 is formed on the hole transport layer 36, a known organic material can be used as the organic light emitting layer 34, and the following can be used. It is possible to emit light of each color by injecting a current between the electrodes sandwiching the organic light emitting layer.

  As the organic light emitting layer 34, for example, a polymer material having a molecular weight of 1000 or more is preferably used. Specifically, a polyfluorene derivative, a polyphenylene derivative, a polyvinyl carbazole, a polythiophene derivative, or perylene is added to these polymer materials. For example, pigments doped with rubrene, perylene, rhodamine, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, quinacridone and the like are used. As such a polymer material, a π-conjugated polymer material in which π electrons of double bonds are non-polarized on the polymer chain is also a conductive polymer, so that it has excellent light emitting performance and is suitable. Used. In particular, a compound having a fluorene skeleton in the molecule, that is, a polyfluorene compound is more preferably used. In addition to such materials, a composition for an organic EL device comprising a precursor of a conjugated polymer organic compound and at least one fluorescent dye for changing light emission characteristics is also used for the light emitting layer. It can be used as a forming material.

  Specifically, the red light emitting layer, the green light emitting layer, and the blue light emitting layer of the organic light emitting layer (R, G, B) 34 can be formed as follows.

  The red light emitting layer (red light emitting layer) is, for example, a blue light emitting layer or a green light emitting layer (blue or green light emitting layer), Neil-red, DCM derivative {DCM: 4-Dicyanmethylene-2- pyran derivatives such as methyl-6 (p-dimethylaminostyryl) -4H-pyran}, DCJT {4- (dicyanomethylene) -2-t-butyl-6- (julolidylstyryl) -pyran}, squarylium derivatives, porphyrin derivatives , A layer doped with a known red dye compound such as a chlorin derivative, a eurodiline derivative, or a rhodamine derivative.

  The green light emitting layer (green light emitting layer) is, for example, a blue light emitting layer (blue light emitting layer), a known green pigment compound such as a coumarin (Coumarin-6, Coumarin-7) derivative such as coumarin, or a quinacridone derivative. Can be formed as a doped layer.

  Blue light-emitting layer (blue light-emitting layer) is doped with known blue pigment compounds such as perylene, oxadiazole derivatives, cyclopentadiene derivatives, pyrazoloquinoline derivatives, distyrylarylene derivatives, oligothiophene derivatives, etc. Can be formed as a layer.

  These dye compounds to be doped are usually used by being doped in an electron transport layer 32 described later. However, when perylene is used for forming a blue light emitting layer, it is doped in a hole transport layer 36 described later. Also good. The dope materials for light emission of each color are not limited to those described above, and other materials may be used as long as they emit light of red, green, or blue. By selecting a compound capable of emitting three primary colors of red, green, and blue, color light emission with high luminous efficiency and good color development can be achieved.

  The thickness of the inorganic light-emitting layer 34 corresponding to R gives an optical film thickness that is an integral multiple of one-half the wavelength of red light to be extracted from the EL element, and the thickness of the inorganic light-emitting layer 34 corresponding to G The thickness of the inorganic light-emitting layer 34 corresponding to B is the blue color that is to be extracted from the EL element. An optical film thickness that is an integral multiple of one-half of the wavelength of light is given. By setting it as such thickness, the influence of interference can be suppressed.

  In the example shown in FIG. 3, in order to clearly show the organic light emitting layer 34, the organic light emitting layer 34 is shown separately from the electron transport layer 32 to be described later. In the case of forming a layer, in the actual organic light emitting layer, the organic light emitting layer and the electron transport layer form the same layer.

  The electron transport layer 32 is formed of, for example, a quinolinol aluminum complex (aluminum quinolinol complex (Alq3) (tris (8-quinolinolate aluminum), tris (8-quinolinolate aluminum)), an oxazole complex of zinc (oxadiazole derivative (OXD, PBD). )), 2- (2-hydroxyphenyl) benzothiazole complex of zinc, triazole derivative (TAZ), phenanthroline derivative (bathocuproine, bathophenanthroline) and the like.

  The cathode 30 is formed as a transparent upper electrode (counter electrode) by a light-transmitting and light-transmitting metal thin film, and includes a light reflecting layer 44 on the lower electrode (anode 38) side and an upper electrode (cathode 30). A cavity (optical resonator) structure is formed between them. A transparent conductive film for supplementing conductivity may be laminated on the metal thin film to form the upper electrode (cathode 30) as a two-layer structure.

  The upper electrode is used as a cathode 30 having a light transmitting property and a light reflecting property and configured as a half mirror. Examples of the material constituting the upper electrode (cathode 30) include Au, Ag, Cu, Cr, and Ni. Metal such as Al, Mg-Ag alloy, transparent conductive film such as ITO, IZO, ZnO, PEDOT / PSS [poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate)] It can be formed by an organic conductive film or the like. Among these, for example, a conductive material having a small work function such as an alloy of an active metal such as Li, Mg, or Ca and a metal such as Ag, Al, or In is selected and used. Good. Since the upper electrode (cathode 30) is used as a half mirror on the side from which light emitted from the light emitting layer is extracted, its light transmittance is adjusted by the film thickness or the like.

  The upper electrode (cathode 30) is formed in a stripe shape that intersects with the stripe of the lower electrode when the display device and the illumination device configured using EL elements are of a simple matrix type. Thus, the laminated portion becomes an EL element. When this display device is an active matrix type, the upper electrode (cathode 30) may be formed as a continuous electrode, and is common to the R, G, and B pixels and as a common electrode of each EL element. Used.

  In each layer of the light emitting layer 34 and the lower electrode (anode 38), the light emitting layer is electrically separated and independent between layers corresponding to R, G, and B, and optical crosstalk is suppressed. Are filled with an insulator 48 having a function of separating and independently separating light emitting layers adjacent to each other optically and optically, and R pixels emitting red light (R), G pixels emitting green light (G), blue light ( An independent light emitting action is ensured in the B pixel that radiates B). In the case where a lighting device is configured using an EL element, at least the layers corresponding to R, G, and B may be electrically separated and independent.

  An electron injection layer may be provided between the upper electrode (cathode 30) and the electron transport layer 32 in contact with the electron transport layer. In general, ITO used as a transparent conductive film has a work function of about 5 eV and is suitable for an anode, but not for a cathode. For this reason, in the configuration in which the upper electrode is a transparent cathode 30, electrons in which a metal having a low work function and an electron transporting organic material are mixed between the organic light emitting layer 34 and the upper electrode made of a transparent conductive film. It is desirable that the electron injection property is improved by laminating the injection layer.

Examples of the electron injection layer include thin films of alkali metals and alkaline earth metals such as Li, Cs, Ca, and Mg, LiF, CsF, CaF ₂ , MgF ₂ , Li ₂ O, and Cs ₂ O, and alkali metals or alkaline earths. It is possible to use a compound of a similar metal or a layer obtained by doping these materials with a material constituting the electron transport layer.

  On the surface of the upper electrode (cathode 30), a multilayer interference film 42 having the same configuration as that of the first embodiment is shared by the R, G, B organic light emitting layer 34 and formed as a multilayer interference filter. Yes. The upper surface of the multilayer interference film 42 is protected from the external environment by the transparent protective layer 50.

The multilayer interference film 42 is
The multilayer in the first embodiment using the center wavelengths of red light emission, green light emission, and blue light emission emitted from the red light emission layer, green light emission layer, and blue light emission layer of the organic light emission layer (R, G, B) 34 Similarly to the case of the interference film (second insulating layer) 12, a high refractive material and a low refractive material are selected, and the film thicknesses of m, a, b, and the refractive material are determined.

  In the above description, the upper electrode (transparent electrode) is provided on the electron transport layer 32 side and functions as the cathode 30, and the lower electrode having the light reflection layer 44 formed on the lower surface is on the hole transport layer 36 side. It is provided and acts as the anode 38. A drive power supply for current injection is connected between the upper electrode and the lower electrode. By injecting current between the upper electrode and the lower electrode, red (R), green (G), blue ( The light emission of B) occurs, these are added and emitted from the upper electrode.

  As in the first embodiment, the organic light emitting layer (an organic light emitting layer R that emits red light, an organic light emitting layer G that emits green light, and an organic light emitting layer B that emits blue light) 34 is organic. The organic white light emitting layer can be replaced with a white light emitting layer. The organic white light emitting layer is formed of a material capable of emitting red light, green light, and blue light, an organic red light emitting layer, an organic green light emitting layer, and an organic blue light. It can be configured by any one of a layer formed by stacking light emitting layers, an organic material emitting red light, a material emitting green light, and an organic material emitting blue light. According to such a structure, an organic white light emitting layer can be formed with fewer steps, and an EL element having a structure corresponding to FIG. 1B can be formed.

  The light emitting part formed inside the upper electrode and the lower electrode of the organic EL element described above includes, for example, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron in order from the lower layer on the lower electrode. Either a structure in which an injection layer is stacked, a structure in which a hole transport layer, an organic light emitting layer, and an electron transport layer are stacked in order from the lower layer on the lower electrode, or a structure in which an organic light emitting layer is stacked on the lower electrode What is necessary is just to have an organic light emitting layer at least on a lower electrode formed by a structure. That is, in the light emitting part, layers other than the organic light emitting layer may be provided as necessary. For example, the hole transport layer and the electron transport layer can be omitted. Further, each layer may have a laminated structure including a plurality of layers.

  As described above, a cavity (optical resonator) structure having a spacer between the light reflecting layer 44 on the lower electrode (anode 38) side and the upper electrode (cathode 30) is formed, and the hole transport layer 36 and the organic layer are formed. The light emitting layer 34 is made of the same material for all of the R, G, and B pixels, but the thickness of the lower electrode (anode 38) is different for the R, G, and B pixels. B pixel <G pixel <R pixel, and the optical film thickness (optical length) of the spacer of the optical resonator in the R, G, B pixels is different between the R, G, B pixels. In other words, the thickness of the lower electrode (anode 38) is adjusted so that the optical film thickness (optical length) of the optical resonator emits predetermined color light from the R, G, and B pixels.

  In the organic EL element configured as described above, when a current flows from the lower electrode (anode 38) to the upper electrode (cathode 30) through the hole transport layer 36 and the organic light emitting layer 34, the organic light emitting layer according to the amount of the current. 34 emits light. The light emitted from the organic light emitting layer 34 passes through the upper electrode (cathode 30) and is emitted to the observer side, while the light emitted from the organic light emitting layer 34 toward the substrate 40 is emitted from the lower electrode. The light is reflected by the reflective layer 44 formed under the (anode 38), passes through the upper electrode (cathode 30), and is emitted to the observer side. At that time, the light emitted from the organic light emitting layer 34 is multiply reflected between the reflective layer 44 and the upper electrode (cathode 30), and the optical film thickness (optical length) of the spacer of the optical resonator is ¼ wavelength. The half width of the wavelength distribution of light corresponding to an integral multiple can be narrowed (that is, the chromaticity is improved). The red light is emitted from the R pixel, the green light is emitted from the G pixel, the blue light is emitted from the B pixel, and is incident on the multilayer interference film (second insulating layer) 42, and the half width of the wavelength distribution of the light of each color Is narrowed, passes through the multilayer interference film 42, is colored, and is emitted from the organic EL element.

  In the above description, the organic EL element having the structure in which the lower electrode is an anode and the upper electrode is a cathode has been described. However, the present invention can be applied to an organic EL element having a lower electrode as a cathode and an upper electrode as an anode. Similar performance can be obtained. In this case, on the upper part of the lower electrode (cathode), the stacking order of the above-described components (hole transport layer 36 → organic light emitting layer (R, G, B) 34 → electron transport layer 32) and reverse order (electron transport layer) 32 → Organic light emitting layer (R, G, B) 34 → Hole transport layer 36), and the upper electrode (anode) is provided.

When the upper electrode is used as an anode, the materials constituting the upper electrode include Ni, Ag, Au, Pt, Pd, Se, Rh, Ru, Ir, Re, W, Mo, Cr, Ta, Nb, These alloys, SnO ₂ , ITO, zinc oxide (ZnO), titanium oxide (TiO ₂ ) and other conductive materials having a large work function are selected and used.

  Further, when the lower electrode is used as a cathode, the above-described materials used when the upper electrode is configured as the cathode 30 can be used as the material constituting the lower electrode.

  As described above, in the second embodiment, the materials of the organic functional layers such as the hole transport layer and the light emitting layer constituting the organic EL element are the same regardless of the corresponding colors (R, G, B). Which color (R, G, B) is determined by the thickness of the lower electrode. That is, an optical resonator structure is configured corresponding to R, G, and B pixels, and the optical film thickness (optical length) of the optical resonator is any of red light, green light, and blue light depending on the thickness of the lower electrode. Set to a value corresponding to. Therefore, when manufacturing the organic EL element, the same material is used for the R, G, and B pixels without using a material specific to the emission color, so that productivity can be improved.

  Note that a display device and a lighting device using the above-described organic EL elements formed on a substrate arranged in a matrix are driven by a simple matrix type or active matrix type driving method (not shown).

EXAMPLE As shown in FIG. 2 (A), m = 1, a = 2.25, b = 3.1, and as described above, layer-1: (λ _g / 4) × 1 / 2.2 = 62 nm, layer-2: (λ _g /4)×1/1.45=94 nm, layer-3: (λ _g /4)×1/2.2=62 nm, layer-4: a × (Λ _g /4)×1/1.45=211 nm, layer −5: b × (λ _g /4)×1/2.2=192 nm, layer −6: a × (λ _g / 4) × 1 /1.45=211 nm, Layer-7: (λ _g /4)×1/2.2=62 nm, Layer-8: (λ _g /4)×1/1.45=94 nm, Layer-9: ( λg / 4 ₎ × 1 / 2.2 ₌ 62 nm The thickness of the first insulating layer (multilayer interference film) 12 in which the layer-1 to the layer-9 are laminated is expressed as TFCalc ^™ (Software Spectra , Inc.).

In the multilayer interference film described above, when the intensity between wavelengths λ and λ + dλ is E (λ) dλ, white light (E (λ) = E _w (λ) where E (λ) is constant regardless of λ. = Constant) was measured for spectral transmission characteristics (transmission spectrum) when perpendicularly incident on the multilayer interference film.

  FIG. 4 is a diagram for explaining the spectral transmission characteristics of the multilayer interference film (second insulating layer) in the embodiment of the present invention, which is a transmission spectrum when white light is vertically incident on the multilayer interference film, The axis represents wavelength (nm) and the vertical axis represents transmittance. As is apparent from the results shown in FIG. 4, the transmittance is large in the wavelength bands of R, G, and B. R, G, and B wavelength bands of about 13 nm and about 25 nm are emitted, and this multilayer interference film acts as a bandpass filter having good characteristics for the R, G, and B wavelength bands. Is clearly shown.

By changing the coefficient a in layer-4, the coefficient in layer-5, and the coefficient a in layer-6 of the multilayer interference film described above, ZnS: Mn as the red light emitting layer, BaAl ₂ S ₄ : Eu, green as the blue light emitting layer. Using ZnS: Tb as the light emitting layer, and as described later, assuming that the light emitting layer has the light emission spectrum shown in FIGS. 7A, 8A, and 9A, the same simulation as above was performed. When the spectrum of the light emitted from the multilayer interference film is obtained and the R, G, B color coordinates of the emitted light are plotted on the CIExy chromaticity diagram, the plotted position is determined by the coefficients a and b. The width of the color reproduction range (the level of color purity) changes depending on the area of the triangle having the three vertexes of the R, G, B color coordinates plotted in this chromaticity diagram.

  FIG. 5 is a CIE chromaticity diagram when the a value defining the film configuration of the multilayer interference film (second insulating layer) is changed (where b = 3.1) in the embodiment of the present invention. It is a figure explaining the movement of the chromaticity point in.

  FIG. 6 is a CIE chromaticity diagram when the b value defining the configuration of the multilayer interference film (second insulating layer) in the embodiment of the present invention is changed (provided that a = 2.25). It is a figure explaining a motion of a chromaticity point.

  As shown in FIG. 5, when a is changed from a = 2 to a = 2.5 with b = 3.1, changes in the color coordinates of R, G, and B are as follows. Regarding the color coordinates of R, the x and y coordinates change in the increasing direction during the change of a = 2 → a = 2.25 → a = 2.5. Regarding the color coordinates of G, the x coordinate is small and the y coordinate is large during the change of a = 2 → a = 2.25, and the change of a = 2.25 → a = 2.5. The x coordinate is large and the y coordinate is small. Regarding the color coordinates of B, the x coordinate does not substantially change during the change of a = 2 → a = 2.25, and the y coordinate changes in a decreasing direction, and a = 2.25 → a = 2.5. The y-coordinate does not substantially change between changes, and the x-coordinate changes slightly smaller.

As shown in FIG. 6, when a = 2.25 and b = 2.7 → b = 3.3 and b is changed, the color coordinates of R, G, and B are changed as follows. Regarding the R color coordinates, the x and y coordinates change in the direction of increasing during the change of b = 2.7 → b = 3.1 → b = 3.3.
Regarding the color coordinates of G, the change in the direction of b = 2.7 → b = 3.1 is such that the x coordinate is small and the y coordinate is large, and the change is b = 2.7 → a = 3.3. The x coordinate is slightly larger and the y coordinate is slightly smaller. Regarding the color coordinates of B, the x coordinate does not substantially change during the change of b = 2.7 → b = 3.1, and the y coordinate changes in a decreasing direction, and b = 3.1 → b = 3. Between the three changes, the y coordinate does not substantially change, and the x coordinate changes in a slightly smaller direction.

  From the results shown in FIGS. 5 and 6, when a = 2.25 and b = 3.1, optimum chromaticity points (coordinates) of R, G, and B are obtained, and the coordinates are R (0. 694, 0.306), G (0.319, 0.568), and B (0.150, 0.055). At this time, the color reproducibility range is divided into NTSC color coordinates (R (0.67, 0.33), G (0.21, 0.71), B (0.14, 0.08)) triangle and area. By comparison, the color reproducibility is 74.8% NTSC, which is superior to CRT, which is said to be 70% NTSC.

Next, assuming that m = 1, a = 2.25, and b = 3.1, an actual R, B is formed on the second insulating layer (multilayer interference film) 12 in which the above-described layers-1 to 9 are stacked. The spectrum of the light emitted from the multilayer interference film when the light is incident from the G light emitting layer was obtained by simulation using TFCalc ^™ (Software Spectra, Inc.) described above.

  FIG. 7 is a diagram illustrating a change in the emission spectrum of the blue phosphor due to the multilayer interference film (second insulating layer) in the embodiment of the present invention. FIG. 7A is a diagram before entering the multilayer interference film. The emission spectrum of the blue phosphor, FIG. 7B is a diagram showing the emission spectrum of the blue phosphor after exiting the multilayer interference film.

FIG. 7A shows an emission spectrum of BaAl ₂ S ₄ that gives blue light incident on the multilayer interference film (see FIG. 3 described in Non-Patent Document 1), and its half-value width is about 30 nm. large. As shown in FIG. 7B, the spectrum of light emitted from the multilayer interference film is narrowed by the action of the multilayer interference film, and its half-value width is half of the half-value width of the spectrum before incidence of about 30 nm. The following is about 13 nm.

  FIG. 8 is a diagram for explaining the change in the emission spectrum of the green phosphor due to the multilayer interference film (second insulating layer) in the embodiment of the present invention. FIG. 8A is a diagram before entering the multilayer interference film. The emission spectrum of the green phosphor, FIG. 8B is a diagram showing the emission spectrum of the green phosphor after exiting the multilayer interference film.

FIG. 8A shows the emission spectrum (measured spectrum) of ZnS: Tb that gives green light incident on the multilayer interference film, and the half-value width corresponding to the transition from ⁵ D _{4 to} ⁷ F _{5 of} Tb is about steep main peak of _{^{10nm, 7 F 6, 7 F}} 4, 7 F 3 is present is secondary emission peak involved, narrowing the color reproduction range (lowering the color purity) causing Yes.

  As shown in FIG. 8B, the spectrum of the light emitted from the multilayer interference film is narrowed by the action of the multilayer interference film, and its half-value width is narrower than the half-value width of the spectrum before incidence. The intensity of the secondary emission peak existing in the spectrum of FIG. 8A is weakened, and the green chromaticity point is changed from (0.315, 0.491) to (0. 319, 0.570).

  FIG. 9 is a diagram for explaining a change in the emission spectrum of the red phosphor due to the multilayer interference film (second insulating layer) in the embodiment of the present invention. FIG. 9A is a diagram before entering the multilayer interference film. The emission spectrum of the red phosphor, FIG. 9B is a diagram showing the emission spectrum of the red phosphor after exiting the multilayer interference film.

  FIG. 9A shows an emission spectrum of ZnS: Mn that gives red light incident on the multilayer interference film (see FIG. 7 described in Non-Patent Document 2), and its half-value width is as large as about 80 nm. It gives orange light rather than red.

  As shown in FIG. 9B, the spectrum of light emitted from the multilayer interference film is narrowed by the action of the multilayer interference film, and consists of two peaks with a half-value width of about 18 nm and about 25 nm. .

EL element having the structure shown in FIG. 1A, for example, a white light-emitting layer formed by mixing materials constituting each phosphor layer of R, G, B, or each phosphor of R, G, B In the EL element shown in FIG. 1B having a white light-emitting layer formed by stacking layers, the spectrum of light emitted from the multilayer interference film has the spectral transmission characteristics of the multilayer interference film shown in FIG. λ), the spectrum of blue light shown in FIG. 7A is E _b (λ), the spectrum of green light shown in FIG. 8A is E _g (λ), and FIG. When the spectrum of red light shown is E _r (λ), it is given by OT (λ) × {E _g (λ) + E _b (λ) + E _r (λ)}.

  As described above, according to the present invention, the same multilayer interference film is disposed in common for the R, G, and B light emitting layers, thereby filtering light emitted due to the transition between secondary levels. The emission from the EL element can be suppressed, the wavelength of the light emitted from the inorganic and organic EL elements having broad emission spectrum characteristics compared to the light emission by the LED, etc. is controlled, and the emitted light Therefore, an EL element with a wide color gamut can be realized by expanding the color reproduction range.

As described above, ZnS: Mn, ZnS: Tb, BaAl ₂ S ₄ : Eu is used as the light emitting layer, SiO ₂ (n = 1.45) as the low refractive index material, and Nb ₂ O ₅ (n = 2) as the high refractive index material. .2), (HL) ^m H (aL) (bH) (aL) H (HL) ^m where m = 1, a = 2.25, b = 3.1. As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, these light emitting layers and high and low refractive index materials can be appropriately selected, and suitable values of m, a, and b can be determined according to these selections.

  As described above, according to the present invention, it is possible to provide an electroluminescence element capable of expanding a chromaticity reproduction range and improving a wide color gamut characteristic, a display device using the same, and an illumination device.

It is sectional drawing which shows typically the structure of an inorganic EL element in the 1st Embodiment of this invention. It is a figure explaining the specific example of a structure of the inorganic EL element shown to FIG. 1 (A) same as the above. It is sectional drawing which shows typically the structure of the organic EL element in the 2nd Embodiment of this invention. It is a figure explaining the spectral transmission characteristic of the multilayer interference film in the Example of the present invention. FIG. 6 is a diagram for explaining the movement of chromaticity points in the CIE chromaticity diagram when the value a defining the film configuration of the multilayer interference film is changed (provided that b = 3.1). FIG. 10 is a diagram for explaining the movement of chromaticity points in the CIE chromaticity diagram when the b value defining the configuration of the multilayer interference film is changed (provided that a = 2.25). It is a figure explaining the change of the emission spectrum of the blue fluorescent substance by a multilayer interference film same as the above. It is a figure explaining the change of the emission spectrum of the green fluorescent substance by a multilayer interference film same as the above. It is a figure explaining the change of the emission spectrum of the red fluorescent substance by a multilayer interference film same as the above. It is an expansion schematic end view of an optical interference type EL element with a small reflectance in a prior art. It is a basic composition sectional view of a thin film electroluminescent device same as the above.

Explanation of symbols

10 ... upper transparent electrode, 12 ... second insulating layer (multilayer interference film), 14 ... light emitting layer (R, G, B),
16 ... 1st insulating layer, 18 ... Metal electrode (lower electrode; counter electrode), 20 ... Insulating substrate,
22 ... insulating material, 24 ... white light emitting layer, 30 ... cathode (upper electrode; counter electrode),
32 ... Electron transport layer, 34 ... Organic light emitting layer (R, G, B), 36 ... Hole transport layer,
38 ... Anode (lower electrode), 40 ... Substrate, 42 ... Multilayer interference film, 44 ... Reflective layer,
46 ... Transparent insulating film, 48 ... Insulating layer, 50 ... Transparent protective layer

Claims (21)

A red light emitting layer that emits red light; and
A green light-emitting layer that emits green light;
A blue light-emitting layer that emits blue light;
An electrode for red light that is provided facing the red light emitting layer and emits the red light;
An electrode for green light provided opposite to the green light emitting layer and emitting the green light;
A blue light electrode provided opposite to the blue light emitting layer and emitting the blue light;
A counter electrode provided opposite to the red light electrode, the green light electrode and the blue light electrode and sandwiching the red light emitting layer, the green light emitting layer and the blue light emitting layer;
A multi-layer interference filter provided in common facing the red light emitting layer, the green light emitting layer and the blue light emitting layer, wherein layers having different refractive indexes are alternately laminated, and the red light emitting layer The electroluminescent element in which the green light emitting layer and the blue light emitting layer are juxtaposed, and the red light electrode, the green light electrode and the blue light electrode are juxtaposed. A white light-emitting layer that emits white light;
An electrode for red light that is provided facing the white light emitting layer and emits red light;
An electrode for green light provided opposite to the white light emitting layer and emitting green light;
An electrode for blue light that is provided facing the white light emitting layer and emits blue light;
A counter electrode provided to face the red light electrode, the green light electrode, and the blue light electrode and sandwich the white light emitting layer;
A multilayer interference filter provided opposite to the white light emitting layer and having layers having different refractive indexes, and the red light electrode, the green light electrode, and the blue light electrode Are electroluminescence elements juxtaposed.   The multilayer interference filter is composed of a high refractive index layer and a low refractive index layer, and is an integral multiple of a quarter of the wavelength λ of the emission center wavelength of the red light, the green light, and the blue light. The electroluminescent device according to claim 1, comprising the high refractive index layer and the low refractive index layer having an optical film thickness. The wavelength λ is the emission center wavelength λ _g of the green light, and the high refractive index layer and the low refractive index layer having an optical film thickness that is an integral multiple of λ _g / 4 are represented by H and L, respectively, m Is a positive integer indicating the repetition of a pair of layers H and L, and a and b are positive numbers, the multilayer interference filter has (HL) ^m H (aL) (bH) (aL) H ( The electroluminescent device according to claim 3, wherein the chromaticity points of the red light, the green light and the blue light represented by LH) ^m are adjusted by a and b.   The multilayer interference filter is provided between the red light electrode, the green light electrode, and the blue light electrode, and the red light emitting layer, the green light emitting layer, and the blue light emitting layer. 2. The electroluminescent device according to 1.   The electroluminescent device according to claim 2, wherein the multilayer interference filter is provided between the red light electrode, the green light electrode, the blue light electrode, and the white light emitting layer.   Insulation for red light having an optical film thickness that is an integral multiple of one-half the emission center wavelength of the red light, facing the red light electrode, and disposed between the red light emitting layer and the counter electrode A green layer disposed between the green light-emitting layer and the counter electrode, having an optical film thickness that is an integral multiple of a half of the emission center wavelength of the green light and facing the green light electrode An optical insulating layer, and an optical film thickness that is an integral multiple of one-half the emission center wavelength of the blue light, and is disposed between the blue light emitting layer and the counter electrode, facing the blue light electrode The electroluminescent element according to claim 1, further comprising: a blue light insulating layer, wherein the red light insulating layer, the green light insulating layer, and the blue light insulating layer are juxtaposed.   Insulation for red light having an optical film thickness that is an integral multiple of one-half the emission center wavelength of the red light, facing the red light electrode, and disposed between the white light emitting layer and the counter electrode A green layer disposed between the white light-emitting layer and the counter electrode, having an optical film thickness that is an integral multiple of a half of the emission center wavelength of the green light and facing the green light electrode An optical insulating layer, and an optical film thickness that is an integral multiple of one-half of the emission center wavelength of the blue light, and is disposed between the white light emitting layer and the counter electrode, facing the blue light electrode The electroluminescent element according to claim 2, further comprising: a blue light insulating layer, wherein the red light insulating layer, the green light insulating layer, and the blue light insulating layer are juxtaposed.   The red light emitting layer has an optical film thickness that is an integral multiple of a half of the emission center wavelength of the red light, and the green light emission layer is an optical film that is an integral multiple of a half of the emission center wavelength of the green light. 2. The electroluminescent device according to claim 1, wherein the electroluminescent element has a film thickness, and the blue light emitting layer has an optical film thickness that is an integral multiple of a half of an emission center wavelength of the blue light.   The red light emission electrode has an optical film thickness that is an integral multiple of one half of the emission center wavelength of the red light, and the green light emission electrode is an integral multiple of one half of the emission center wavelength of the green light. The electroluminescent element according to claim 1, wherein the blue light-emitting electrode has an optical film thickness that is an integral multiple of one-half the emission center wavelength of the blue light.   The counter electrode is provided in common to the red light electrode, the green light electrode, and the blue light electrode across the red light emitting layer, the green light emitting layer, and the blue light emitting layer. The electroluminescent device according to claim 1, wherein the electroluminescent device is a common electrode.   The counter electrode is a common electrode provided in common to these electrodes facing the red light electrode, the green light electrode, and the blue light electrode with the white light emitting layer interposed therebetween. The electroluminescent device according to 1.   The electroluminescent device according to claim 1, wherein a space between two phosphor layers of the red light emitting layer, the green light emitting layer, and the blue light emitting layer is filled with an insulator.   The counter electrode, the juxtaposed red light emitting layer, the green light emitting layer and the blue light emitting layer, the multilayer interference filter, the juxtaposed red light electrode, the green light electrode and the blue light electrode The electroluminescent device according to claim 1, wherein an element is formed by sequentially laminating the substrate, and light is emitted from a side of the substrate on which the element is formed.   The counter electrode, the white light emitting layer, the multilayer interference filter, the juxtaposed red light electrode, the green light electrode, and the blue light electrode are laminated on the substrate in this order to form an element. The electroluminescent element according to claim 2, wherein light is emitted from a side on which the element is formed.   2. The electroluminescent device according to claim 1, wherein the multilayer interference filter is provided to face the red light emitting layer, the green light emitting layer, and the blue light emitting layer with the counter electrode interposed therebetween.   The electroluminescent element according to claim 2, wherein the multilayer interference filter is provided so as to face the white light emitting layer and sandwich the counter electrode.   The juxtaposed red light electrode, the green light electrode and the blue light electrode, the juxtaposed red light emitting layer, the green light emitting layer and the blue light emitting layer, the counter electrode, and the multilayer interference filter, The electroluminescent element according to claim 1, wherein an element is formed by laminating on the substrate in this order, and light is emitted from a side of the substrate where the element is formed.   The red light electrode, the green light electrode and the blue light electrode, the white light emitting layer, the counter electrode, and the multilayer interference filter, which are juxtaposed, are laminated on the substrate in this order to form an element, The electroluminescent element according to claim 2, wherein light is emitted from a side of the substrate on which the element is formed.   A display device in which the electroluminescent elements according to any one of claims 1 to 19 are arranged in a two-dimensional matrix.   The illuminating device in which the electroluminescent element of any one of Claims 1-19 was arranged in two-dimensional matrix form.

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