JP2007227232A - Lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bright lighting system by suppressing dispersion of luminance in a light emitting region when the area of the lighting system is increased. <P>SOLUTION: A plurality of light emitting cells each comprising a first light emitting unit 14, an intermediate conductive layer 16, a second light emitting unit 18, and a first electrode 12 and a second electrode 20 sandwiching the light emitting units therebetween are formed and serially connected to one another on a substrate 10. The serial connection is formed into a structure where the second electrode 20a of the first light emitting cell 101 and the first electrode 12b of the second light emitting cell 102 are connected to each other in a second opening 19b formed in the light emitting unit. The intermediate layer 16 includes a structure formed in the inside without reaching the light emitting unit 14 and the other end of the light emitting unit 20. By virtue of this structure, influence of resistance loss caused by high resistivity of a transparent conductive film constituting the one-side electrode relative to that of a metal electrode constituting the other-side electrode can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a lighting device using electroluminescence (EL).

Conventionally, an organic electroluminescence element (hereinafter also referred to as an organic EL element) that emits light with a luminance of 100 to 1000 cd / m ² by applying a voltage of about 10 V is known. Since the organic EL element can be reduced in thickness and weight, application to a display device or a lighting device is expected. However, it has been pointed out that in order to put it into practical use, it is necessary to suppress further improvements in brightness and deterioration.

In an organic EL element in which a light emitting layer is sandwiched between a pair of electrodes, it is necessary to form at least one electrode with a transparent conductive film in order to emit light to the outside. The transparent conductive film is mainly composed of indium oxide or zinc oxide, but has a resistivity of about 5 × 10 ⁻⁴ Ω · cm, which is 100 times higher than 3 × 10 ⁻⁶ Ω · cm of aluminum. Are known. That is, when the organic EL element is used as a surface light source for illumination purposes, it is necessary to solve the resistance loss due to the transparent conductive film in order to emit light with the same luminance on the entire surface. In order to solve this problem, a structure in which an auxiliary electrode having an electric resistance lower than that of the anode is provided in at least a part of the anode has been reported (see Patent Document 1).
JP 2004-134282 A

However, in the case where the auxiliary electrode is provided, when the lighting device is increased in area, the luminance is lowered at a portion away from the auxiliary electrode (for example, the central portion of the lighting device). When the area of the auxiliary electrode is enlarged, the effective light emission area is reduced.

A method of dividing a plurality of EL elements having a small area on the same substrate and connecting them in series or in parallel is conceivable. In this case, since the region for connecting a plurality of EL elements does not emit light, the effective light emitting area in the lighting device is reduced. That is, the luminance efficiency converted per unit area of the lighting panel in the lighting device is lowered.

Therefore, an object of the present invention is to provide a bright illumination device that suppresses variations in luminance within the light emitting region when the illumination device is enlarged in area.

The present invention is an illumination device including a plurality of light emitting cells in which a plurality of light emitting units each having at least one light emitting layer are connected in series between a pair of electrodes. The plurality of light emitting cells are electrically connected between the light emitting cells in which one electrode and the other electrode of the pair of electrodes are different so as to be connected in series. An intermediate conductive layer is provided between one light emitting unit and another light emitting unit that are in a serial connection relationship. The intermediate conductive layer includes a configuration provided on the inner side that does not reach the end of one light-emitting unit and another light-emitting unit.

In the lighting device of the present invention, in a configuration in which a plurality of light emitting cells are connected so that the plurality of light emitting cells are connected in series, one electrode and the other electrode of the pair of electrodes are formed on the light emitting layer. The structure connected by the opening which exposes an electrode is included.

In the present invention, the light-emitting unit is typically composed of a base material containing Group 12 and Group 15 elements of the periodic rule and one or a plurality of layers containing an impurity element that forms a light emission center. A light emitting unit refers to an element excluding a pair of electrodes and an intermediate conductive layer.

An intermediate conductive layer is sandwiched between one light-emitting unit and another light-emitting unit. When one of a pair of electrodes is an anode and the other is a cathode, holes are injected in the cathode direction of the element, and in the anode direction. A layer that has the function of injecting electrons.

A light emitting cell refers to a structure in which a light emitting unit is sandwiched between a pair of electrodes, and may include a stacked body and a layer structure or an electrode structure associated therewith.

Equipped with a plurality of light-emitting cells with a light-emitting layer interposed between a pair of electrodes, and electrically connecting between the light-emitting cells in which one electrode of the pair of electrodes and the other electrode are different so that the plurality of light-emitting cells are connected in series By doing so, it is possible to emit light stably. That is, it is possible to suppress the influence of resistance loss due to the fact that the resistivity of the transparent conductive film constituting one of the pair of electrodes is higher than that of the metal electrode.

By providing an intermediate conductive layer between one light-emitting unit and another light-emitting unit, light emission luminance can be increased without increasing current density. In addition, by providing the intermediate conductive layer on the inner side that does not reach the end portions of one light emitting unit and another light emitting unit, leakage current between adjacent light emitting cells can be suppressed.

In a configuration in which a plurality of light emitting cells are connected, one electrode of the pair of electrodes and the other electrode are connected by an opening formed in the light emitting layer and exposing one of the electrodes, thereby effectively emitting light. It is possible to increase the area of the light emitting cell that contributes to the above.

With this configuration, when the lighting device has a large area, variation in luminance within the light emitting region can be suppressed and a bright lighting device can be provided.

In the present invention, a plurality of light emitting units each having at least one light emitting layer are connected in series between a pair of electrodes, and an intermediate conductive layer is provided between one light emitting unit and another light emitting unit in the series connection relationship. It is an illuminating device provided with the several light emitting cell provided. Among the plurality of light emitting cells, adjacent ones are connected in series with each other. That is, one electrode and the other electrode in a pair of electrodes are connected in series between different light emitting cells. The light emitting cells are formed in a strip shape, and a plurality of light emitting cells are arranged in the short direction to form an electrical series connection.

In this way, by dividing the light emitting cell into a plurality of pieces and connecting them in series, it is possible to suppress the resistance loss affected by one or both of the pair of electrodes. For example, when one electrode is formed of a transparent conductive film containing indium oxide or zinc oxide as a main component, the resistivity is about 5 × 10 ⁻⁴ Ω · cm, which is about 100 times higher than that of a metal such as aluminum. . In this case, the light emitting cells are formed in a strip shape, and a plurality of light emitting cells are arranged so as to form a series connection in the short direction, thereby suppressing an increase in series resistance even when the area of the light emitting portion in the lighting device increases. be able to.

One electrode of the pair of electrodes is preferably a transparent electrode, and the other electrode is preferably a light reflective electrode. Since the light emitting cell emits light, it is possible to effectively emit light by forming at least one of them with a transparent electrode. The other electrode is preferably formed of a metal having a high reflectance in at least the visible light band. This is effective for radiating the light emitted from the light emitting unit onto the surface on which the transparent electrode is formed. As another embodiment, both electrodes can be formed of transparent electrodes. With this configuration, light can be emitted from both sides of the light emitting cell. Therefore, a design can be elaborated as an illuminating device.

In a structure in which a plurality of light emitting cells are connected in series, the structure of the electrical connection portion affects the effective light emitting area in the lighting device. When this illumination device is regarded as a surface light source, the effective luminance (luminance per light emitting panel) is affected. Therefore, it is desirable that the area of the series connection portion that does not contribute to light emission is as small as possible. The light emitting cell has a configuration in which a pair of electrodes and a plurality of light emitting units are connected in series, and an electrical connection is formed by forming an opening in the light emitting unit to expose an electrode under the light emitting unit. To do. Using this opening, one electrode and the other electrode of a pair of electrodes are connected in series between different light emitting cells. The opening is formed by directly processing the light emitting unit. That is, it can be formed by removing the thin film. In addition, a similar connection structure can be formed even if the strip-shaped or rectangular first electrode, the second electrode, and the light-emitting unit are shifted in the short direction as the pair of electrodes.

In this way, in the structure in which one electrode and the other electrode in a pair of electrodes are connected in series between different light emitting cells, by forming an opening in the light emitting unit to expose the electrode under the light emitting unit, The area required for connection can be reduced. By forming the opening for forming the electrical connection portion on the inner side that does not reach the end portion of the substrate on which the light emitting cell is formed, the leakage current of the light emitting cell can be suppressed.

Regarding the configuration of the light emitting cell, it is preferable that an intermediate conductive layer is provided between one light emitting unit and another light emitting unit that are in series connection with each other on the inner side that does not reach the end of the light emitting unit. The intermediate conductive layer is sandwiched between one light-emitting unit and another light-emitting unit. When one of a pair of electrodes is an anode and the other is a cathode, holes are injected in the cathode direction of the element and electrons in the anode direction. It is a layer with the function of injecting.

As the intermediate conductive layer, a transparent conductive film material that can transmit visible light can be used. Examples of the transparent conductive film material include indium oxide, indium tin oxide, zinc oxide, and indium zinc oxide, and are selected from conductive metal oxides.

Another form of the intermediate conductive layer may be a laminated structure in which a hole generating layer is disposed on the cathode side and an electron generating layer is disposed on the anode side. The hole generation layer is a composite material of an inorganic compound and an organic compound. In this layer, the inorganic compound is a substance that exhibits an electron accepting property with respect to the organic compound, and the organic compound is a substance having an excellent hole transporting property. . Although it is not particularly limited as an inorganic compound, transition metal oxides are preferable, specifically titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, Rhenium oxide is preferred.

As the organic compound, a hole transporting organic compound having a hole mobility of 10 ⁻⁶ cm ² / V · sec or more is preferably used. For example, 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N -Phenylamino] triphenylamine (abbreviation: MTDATA), 1,3,5-tris [N, N-di (m-tolyl) amino] benzene (abbreviation: m-MTDAB), 4,4'-bis [N -(3-Methylphenyl) -N-phenylamino] biphenyl (abbreviation: TPD), 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB), 4,4 '-Bis {N- [4- (N, N-di-m-tolylamino) phenyl] -N-phenylamino} biphenyl (abbreviation: DNTPD), 4,4', 4 ''-tris (N-carbazolyl) Triphenylamine (abbreviation: TCTA) Typified by aromatic amine compound so What about the holes likely to occur, it is a suitable group of compounds as the organic compound. The electron generation layer is not particularly limited as long as it is a layer capable of generating electrons, and specifically includes a layer having an electron-transporting organic compound and a substance that exhibits an electron donating property to the organic compound. It only has to be.

As the electron-transporting organic compound, tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] - quinolinato) beryllium (abbreviation: BeBq _2), bis (2-methyl-8-quinolinolato) -4-phenylphenolato - aluminum (abbreviation: BAlq), bis [2- (2-hydroxyphenyl) benzoxazolato] Zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (abbreviation: Zn (BTZ) ₂ ), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 2 -(4-Biphenylyl) -5- (4-tert-butylphenyl) -1,3,4 -Oxadiazole (abbreviation: PBD), 1,3-bis [5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 3- (4-biphenylyl) -4-phenyl- 5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 3- (4-biphenylyl) -4- (4-ethylphenyl) -5- (4-tert-butylphenyl) ) -1,2,4-triazole (abbreviation: p-EtTAZ) can be used. In addition, examples of the substance exhibiting an electron donating property include alkali metals or alkaline earth metals such as lithium, magnesium, calcium, and barium, or alloys thereof. Alternatively, an alkali metal compound or an alkaline earth metal compound such as lithium oxide, barium oxide, lithium nitride, magnesium nitride, or calcium nitride can be used.

The number of light emitting units connected in series via the intermediate conductive layer is not limited to two layers. If an intermediate conductive layer is provided each time a light emitting unit is stacked, two or more light emitting units can be stacked. By arranging a plurality of light emitting units separated by an intermediate conductive layer between the pair of electrodes, the light emitting cell can emit light with high luminance while keeping the current density low. In particular, in the case of illumination, the voltage drop due to the resistance of the electrode material can be reduced, so that uniform light emission over a large area is possible. Further, by providing such an intermediate conductive layer on the inner side that does not reach the end of the light emitting unit, it is possible to prevent leakage current from flowing between different light emitting cells.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following examples, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the following examples. Note that in the structures of the present invention described below, reference numerals indicating the same elements are used in common in different drawings, and repetitive description in that case may be omitted.

In this embodiment, in a lighting device using electroluminescence, a configuration for suppressing a variation in luminance in a light emitting region and providing a bright lighting device will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a method and structure for manufacturing a lighting device according to the present embodiment, and FIG. 2 is a plan view of the same. The following description will be given with reference to both figures as appropriate.

A first electrode which is one electrode of the light emitting cell is formed over the substrate. When the first electrode is formed using a transparent electrode, it is preferably formed using an oxide conductive material such as indium oxide, indium tin oxide, zinc oxide, or indium zinc oxide. When the first electrode is a reflective electrode, it is typically preferable to use aluminum. This is because aluminum has a high reflectance in the visible light band and can be easily formed by a vacuum deposition method or a sputtering method. As other metals, titanium, tantalum, molybdenum, tungsten, silver, or the like can be used.

The first electrode is preferably divided into a plurality of parts on one substrate. This is for forming a plurality of light emitting cells on the substrate. The number of divisions of the first electrode on one substrate is arbitrary, but it is preferable to determine the dimensions in consideration of the influence of series resistance when the light emitting cell is formed. The shape of the first electrode after the division is also arbitrary, but in the case of a rectangle or a strip, it is preferable that the light emitting cells are arranged in series in the short direction. This is to suppress the influence of the series resistance due to the first electrode.

FIGS. 1A and 2A show a state in which the first electrodes 12 a, 12 b, and 12 c divided into a plurality of parts are formed on the substrate 10. This can be formed by forming the first openings 13 a, 13 b, and 13 c after forming a transparent conductive film or a metal film on the entire surface of the substrate 10. The first opening may be directly processed by a transparent conductive film or a metal film by laser processing or lift-off processing, or may be etched by forming a mask pattern on the substrate using a photolithography technique. . The first openings 13a and 13b are provided to separate and separate the first electrodes.

The first openings 13c and 13d are provided in a direction parallel to the direction in which the light emitting cells are connected in series in the substrate 10 (long side direction of the substrate). The first openings 13c and 13d are provided because the first electrode is substantially inseparable when a transparent conductive film or a metal film is formed around the end face of the substrate 10 and formed. Is preferred.

Next, a first light emitting unit, an intermediate conductive layer, and a second light emitting unit are formed. The first light-emitting unit and the second light-emitting unit are typically formed using a base material containing a Group 12 and Group 15 element in the periodic table and one or a plurality of layers containing an impurity element that forms a light emission center. . The intermediate conductive layer preferably has a structure in which a hole generating layer and an electron generating layer are stacked. This is because the light emitted from the first light emitting unit and the second light emitting unit is effectively extracted. In addition, a transparent conductive film material such as indium oxide, indium tin oxide, zinc oxide, or indium zinc oxide may be used. In addition, the structure of the light emitting cell provided with the light emitting unit, the intermediate conductive layer, and both will be described in detail in Example 4 and Example 5.

The first light emitting unit, the intermediate conductive layer, and the second light emitting unit are sequentially formed on the divided first electrodes 12a, 12b, and 12c. Then, a second opening is formed and divided into a plurality.

1B and 2B show a state in which second openings 19a, 19b, and 19c that separate the first light emitting unit, the intermediate conductive layer, and the second light emitting unit are formed. Thus, the first light emitting unit 14a, the intermediate conductive layer 16a, and the second light emitting unit 18a are formed corresponding to the first electrode 12a. Similarly, the first light emitting unit 14b, the intermediate conductive layer 16b, and the second light emitting unit 18b are formed corresponding to the first electrode 12b, and the first light emitting unit corresponding to the first electrode 12c. 14c, the intermediate conductive layer 16c, and the second light emitting unit 18c are formed. The stacked body of the first light emitting unit, the intermediate conductive layer, and the second light emitting unit is formed so as to cover the first openings 13a, 13b, and 13c and to cover the end portions of the first electrodes 12b and 12c. May be.

The second openings 19a, 19b, and 19c separate the first light emitting unit, the intermediate conductive layer, and the second light emitting unit, and expose the first electrodes 12a, 12b, and 12c. The exposed surface may be the surface of the first electrode, or a new surface removed by slightly etching the first electrode. Alternatively, the first electrode may be removed along with the second opening to expose the side end face.

Next, the second electrode is formed so as to be in contact with the second light emitting unit and to be in contact with the exposed surface of the first electrode through the second opening. The second electrode is formed of a transparent power transmission film or a metal film. In this case, when the first electrode is formed of a transparent conductive film, the second electrode is preferably formed of a metal film. When the first electrode is formed of a metal film, the second electrode can be formed of a transparent conductive film. Moreover, you may form both with a transparent conductive film. The second electrode forms a film over the entire surface of the second light-emitting unit, forms a third opening, and forms a pair with the first electrode.

FIG. 1C and FIG. 2C show a state in which the second electrodes 20a, 20b, 20c, and 20d are formed. The third openings 21a, 21b, 21c separate the second electrode. The second electrode 20a is formed corresponding to the first electrode 12a, and the first light emitting unit 14a, the intermediate conductive layer 16a, and the second light emitting unit 18a are sandwiched therebetween. These together form the first light emitting cell 101. The second electrode 20a is in electrical contact with the adjacent first electrode 12b via the second opening 19b. The second electrode 20b is formed corresponding to the first electrode 12b, and the first light emitting unit 14b, the intermediate conductive layer 16b, and the second light emitting unit 18b are sandwiched therebetween. These together form the second light emitting cell 102. The second electrode 20b is in electrical contact with the adjacent first electrode 12c via the second opening 19c. The second electrode 20c is formed corresponding to the first electrode 12c, and the first light emitting unit 14c, the intermediate conductive layer 16c, and the second light emitting unit 18c are sandwiched therebetween. These together form a third light emitting cell 103.

In this manner, the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103 can be connected in series on the substrate 10 by forming an opening corresponding to each layer. Note that the second electrode 20 d is an extraction terminal of the first electrode 12 a in the first light emitting cell 101. That is, the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103 can emit light by applying a predetermined voltage between the second electrode 20d and the second electrode 20c. it can.

The lighting device according to the present embodiment does not need to route electrical wiring when connecting a plurality of light emitting cells in series, and can be electrically connected only by the laminated films. Thereby, the contact failure in an illuminating device can be eliminated.

Moreover, since the illuminating device according to the present embodiment divides a plurality of light emitting cells on a single substrate and is connected in series, resistance loss due to the use of a transparent electrode can be suppressed. Thereby, even if the area of the light emission part in an illuminating device increases, the increase in series resistance can be suppressed. In a structure in which one electrode and the other electrode of a pair of electrodes are connected in series between different light emitting cells, an opening for exposing an electrode under the light emitting unit is formed in the light emitting unit, so that the connection is made. The required area can be reduced.

This embodiment is for providing a bright illumination device that suppresses variations in luminance in the light emitting region in an illumination device that uses electroluminescence. FIG. 3 and FIG. This will be described with reference to FIG. FIG. 3 is a cross-sectional view for explaining a method and a structure for manufacturing a lighting device according to this embodiment, and FIG. 4 is a plan view thereof. The following description will be given with reference to both figures as appropriate. Further, in this embodiment, the process is the same as that of Embodiment 1 until the first electrode is separately formed on the substrate, so that the description thereof is omitted.

3A and 4A, the first light-emitting unit 14 is formed so as to cover the first electrodes 12a, 12b, and 12c. On top of this, intermediate conductive layers 16a, 16b and 16c are formed separately. The intermediate conductive layer is preferably formed of a transparent conductive film material such as indium oxide, indium tin oxide, zinc oxide, or indium zinc oxide. This is because the light emitted from the first light emitting unit and the second light emitting unit is effectively extracted. The intermediate conductive layer can be formed by an electron beam evaporation method, a sputtering method, or the like. In this case, a shadow mask (a mask formed of a metal or ceramic with an opening formed in a predetermined pattern. Closed to the substrate during film formation to physically block the adhesion of the coating, Can be formed in a divided state on the first light emitting unit 14. Needless to say, the method for separately forming the intermediate conductive layer is not limited to this, and the intermediate conductive layer may be selectively processed by forming a mask pattern using a photolithography technique. The intermediate conductive layers 16 a, 16 b, and 16 c that are separately formed are formed on the inner side that does not reach the end of the first light emitting unit 14. Thereafter, a second light emitting unit is formed, and an opening is formed as in the first embodiment.

3B and 4B show a state in which second openings 19a, 19b, and 19c that separate the first light emitting unit, the intermediate conductive layer, and the second light emitting unit are formed. . Thus, the first light emitting unit 14a, the intermediate conductive layer 16a, and the second light emitting unit 18a are formed corresponding to the first electrode 12a. Similarly, the first light emitting unit 14b, the intermediate conductive layer 16b, and the second light emitting unit 18b are formed corresponding to the first electrode 12b, and the first light emitting unit corresponding to the first electrode 12c. 14c, the intermediate conductive layer 16c, and the second light emitting unit 18c are formed.

3C and 3C show a state in which the second electrodes 20a, 20b, 20c, and 20d are formed in the same manner as in the first embodiment. The third openings 21a, 21b, 21c separate the second electrode. In this manner, the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103 can be connected in series on the substrate 10.

In this case, the end portions of the intermediate conductive layers 16a, 16b, and 16c are covered with the second light emitting units 18a, 18b, and 18c. That is, the intermediate conductive layers 16a, 16b, and 16c are formed inside the first light emitting units 14a, 14b, and 14c and the second light emitting units 18a, 18b, and 18c, respectively. With such a configuration, the intermediate conductive layers 16a, 16b, and 16c can be configured such that the end portions are not exposed in the second openings 19a, 19b, and 19c. The same applies to the peripheral edge region of the substrate 10. Accordingly, the intermediate conductive layers 16a, 16b, and 16c can be structured not to contact the second electrodes 20a, 20b, and 20c at the second openings 19a, 19b, and 19c, respectively.

This structure is useful when a transparent conductive film having a relatively high conductivity is used as the intermediate conductive layer. That is, it is possible to prevent leakage current from flowing to the second electrode due to the intermediate conductive layer. The same applies to the substrate end regions of the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103.

Since other configurations are the same as those of the first embodiment, the same operational effects can be achieved. In addition, the structure of the light emitting cell provided with the light emitting unit, the intermediate conductive layer, and both will be described in detail in Example 4 and Example 5.

The present embodiment is for providing a bright illumination device that suppresses variations in luminance within the light emitting region in an illumination device that uses electroluminescence, and has a configuration different from those of the first and second embodiments. This will be described with reference to FIGS. In this embodiment, a method for manufacturing a lighting device in a relatively simple manner using a shadow mask when forming a film will be described. Note that FIG. 5 is a cross-sectional view illustrating a method and a structure for manufacturing a lighting device according to the present embodiment, and FIG. 6 is a plan view of the same. The following description will be given with reference to both figures as appropriate.

5A and 6A show a state in which the first electrodes 12a, 12b, and 12c divided into a plurality of parts are formed on the substrate 10. FIG. Further, the first light emitting unit 14a and the intermediate conductive layer 16a are formed on the first electrode 12a, the first light emitting unit 14b and the intermediate conductive layer 16b are formed on the first electrode 12b, and the first electrode A state in which the first light emitting unit 14c and the intermediate conductive layer 16c are formed on 12c is shown.

When the first electrode is formed using a transparent electrode, it is preferably formed using an oxide conductive material such as indium oxide, indium tin oxide, zinc oxide, or indium zinc oxide. When the first electrode is a reflective electrode, it is typically preferable to use aluminum. As other metals, titanium, tantalum, molybdenum, tungsten, silver, or the like can be used. The first electrode can be separately formed into a plurality using a shadow mask during film formation by vacuum evaporation or sputtering. Alternatively, it can be formed by screen printing using a conductive paste. In this case, as shown in FIG. 6A, the first electrodes 12a, 12b, and 12c are preferably formed on the inner side that does not reach the end portion of the substrate 10. Thereby, current leaking through the end of the substrate 10 can be prevented.

Similarly, the first light emitting unit and the intermediate conductive layer are separately formed into a plurality using a shadow mask during film formation by vacuum evaporation or sputtering. Since the first light emitting unit and the intermediate conductive layer can be continuously formed, they are formed in substantially the same pattern. In other words, since the first light emitting unit and the intermediate conductive layer are formed using the same shadow mask, the intermediate conductive layer can be prevented from coming into contact with the first electrode.

FIG. 5B and FIG. 6B show a state in which the second light emitting unit is formed. The second light emitting unit is formed with a shadow mask different from that of the first light emitting unit. In this case, the second light emitting unit 18a is formed on the intermediate conductive layer 16a and is formed so as to cover the side end portion and the side end portion of the first light emitting unit 14a. The same applies to the second light emitting unit 18b and the second light emitting unit 18c. The second light emitting unit does not completely cover the first electrode, and is formed so as to expose at least one side end. Such a shape can be formed using a shadow mask.

5C and 6C show a state in which the second electrodes 20a, 20b, and 20c are formed using a shadow mask. The second electrode 20a is formed corresponding to the first electrode 12a, and the first light emitting unit 14a, the intermediate conductive layer 16a, and the second light emitting unit 18a are sandwiched therebetween. These together form the first light emitting cell 101. The second electrode 20b is formed corresponding to the first electrode 12b, and the first light emitting unit 14b, the intermediate conductive layer 16b, and the second light emitting unit 18b are sandwiched therebetween. These together form the second light emitting cell 102. The second electrode 20c is formed corresponding to the first electrode 12c, and the first light emitting unit 14c, the intermediate conductive layer 16c, and the second light emitting unit 18c are sandwiched therebetween. These together form a third light emitting cell 103.

The second electrode is in contact with the second light emitting unit and forms an electrical connection relationship with the first electrode of the adjacent light emitting cell. That is, the second electrode 20a extends so as to be in electrical contact with the adjacent first electrode 12b. The second electrode 20b extends so as to be in electrical contact with the adjacent first electrode 12c. Note that the second electrode 20 d is an extraction terminal of the first electrode 12 a in the first light emitting cell 101. That is, the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103 can emit light by applying a predetermined voltage between the second electrode 20d and the second electrode 20c. it can.

In this manner, the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103 can be connected in series on the substrate 10. In this case, the end portions of the intermediate conductive layers 16a, 16b, and 16c are covered with the second light emitting units 18a, 18b, and 18c. That is, the intermediate conductive layers 16a, 16b, and 16c are formed inside the first light emitting units 14a, 14b, and 14c and the second light emitting units 18a, 18b, and 18c, respectively. With such a configuration, the intermediate conductive layers 16a, 16b, and 16c can be configured not to contact the second electrodes 20a, 20b, and 20c, respectively.

Similar to the second embodiment, this structure is a structure that can prevent leakage current from flowing to the second electrode due to the intermediate conductive layer. The same applies to the substrate end regions of the first light emitting cell 101, the second light emitting cell 102, and the third light emitting cell 103.

Since other configurations are the same as those in the first and second embodiments, the same operational effects can be achieved. In addition, the structure of the light emitting cell provided with the light emitting unit, the intermediate conductive layer, and both will be described in detail in Example 4 and Example 5.

In this example, a light-emitting material suitable as a light-emitting layer of a light-emitting unit is described. The light-emitting material exemplified in this example can be applied to the light-emitting units of Examples 1 to 3. Note that the light-emitting material exemplified in this embodiment is a material including a base material and at least one impurity element which serves as a light emission center. Note that these impurity elements do not include elements constituting the base material.

As the base material used for the light-emitting material, sulfide, oxide, or nitride is used as an inorganic material. Examples of the sulfide include zinc sulfide (ZnS), cadmium sulfide (CdS), calcium sulfide (CaS), yttrium sulfide (Y ₂ S ₃ ), gallium sulfide (Ga ₂ S ₃ ), strontium sulfide (SrS), sulfide. Barium (BaS) or the like can be used. As the oxide, for example, zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), or the like can be used. As the nitride, for example, aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), or the like can be used. Furthermore, zinc selenide (ZnSe), zinc telluride (ZnTe), and the like can also be used. Calcium sulfide-gallium sulfide (CaG _a 2S ₄ ), strontium sulfide-gallium sulfide (SrGa ₂ S ₄ ), barium sulfide-gallium (BaGa). Ternary mixed crystals such as ₂ S ₄ ).

As an impurity element, manganese (Mn), copper (Cu), samarium (Sm), terbium (Tb), erbium (Er), thulium (as a light emitting center utilizing inner-shell electronic transition of a metal ion) Metal elements such as Tm), europium (Eu), cerium (Ce), and praseodymium (Pr) can be used. Note that a halogen element such as fluorine (F) or chlorine (Cl) may be added as charge compensation.

In addition, a light-emitting material including a first impurity element and a second impurity element can be used as a light-emission center using donor-acceptor recombination. As the first impurity element, for example, a metal element such as copper (Cu), silver (Ag), gold (Au), platinum (Pt), silicon (Si), or the like can be used. Examples of the second impurity element include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium. (Tl) or the like can be used.

The light-emitting material according to this example is a solid-phase reaction, that is, a base material and an impurity element are weighed, mixed in a mortar, and heated and reacted in an electric furnace to cause the base material to contain the impurity element. For example, the base material, the first impurity element or the compound containing the first impurity element, and the second impurity element or the compound containing the second impurity element are weighed and mixed in a mortar, Heat and fire. The firing temperature is preferably 700 to 1500 ° C. This is because the solid reaction does not proceed when the temperature is too low, and the base material is decomposed when the temperature is too high. In addition, although baking may be performed in a powder state, it is preferable to perform baking in a pellet state.

In addition, as an impurity element in the case of using a solid phase reaction, a compound composed of a first impurity element and a second impurity element may be used in combination. In this case, since the impurity element is easily diffused and the solid-phase reaction easily proceeds, a uniform light emitting material can be obtained. Further, since no extra impurity element is contained, a light-emitting material with high purity can be obtained. Examples of the compound composed of the first impurity element and the second impurity element include copper fluoride (CuF ₂ ), copper chloride (CuCl), copper iodide (CuI), copper bromide (CuBr), and nitride Copper (Cu ₃ N), copper phosphide (Cu ₃ P), silver fluoride (CuF), silver chloride (CuCl), silver iodide (CuI), silver bromide (CuBr), gold chloride (AuCl ₃ ), Gold bromide (AuBr ₃ ), platinum chloride (PtCl ₂ ), or the like can be used. Alternatively, a light emitting material containing a third impurity element may be used instead of the second impurity element.

Examples of the third impurity element include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), nitrogen (N), phosphorus (P), arsenic (As), and antimony. (Sb), bismuth (Bi), or the like can be used. The concentration of these impurity elements may be 0.01 to 10 mol%, preferably 0.1 to 5 mol%, based on the base material.

As a light-emitting material having high electrical conductivity, a light-emitting material in which the above-described material is used as a base material and a light-emitting material containing the first impurity element, the second impurity element, and the third impurity element is added. Can be used. The concentration of these impurity elements may be 0.01 to 10 mol%, preferably 0.1 to 5 mol% with respect to the base material.

Examples of the compound composed of the second impurity element and the third impurity element include lithium fluoride (LiF), lithium chloride (LiCl), lithium iodide (LiI), copper bromide (LiBr), and sodium chloride. Alkaline halides such as (NaCl), boron nitride (BN), aluminum nitride (AlN), aluminum antimony (AlSb), gallium phosphide (GaP), gallium arsenide (GaAs), indium phosphide (InP), indium arsenide (InAs) Indium antimony (InSb) or the like can be used.

A light-emitting layer using the above-described material as a base material and using the above-described light-emitting material including the first impurity element, the second impurity element, and the third impurity element requires hot electrons accelerated by a high electric field. Without emitting light. That is, since it is not necessary to apply a high voltage to the light emitting element, a light emitting element that can operate with a low driving voltage can be obtained. In addition, since light can be emitted with a low driving voltage, a light-emitting element with reduced power consumption can be obtained. Further, an element that becomes another light emission center may be included.

Alternatively, the above-described material can be used as a base material, and a light-emitting material including a light-emitting center using the second impurity element, the third impurity element, and the above-described inner-shell electron transition of a metal ion can be used. In this case, the metal ion serving as the emission center is preferably 0.05 to 5 atom% with respect to the base material. The concentration of the second impurity element is preferably 0.05 to 5 atom% with respect to the base material. The concentration of the third impurity element is preferably 0.05 to 5 atom% with respect to the base material. The light emitting material having such a structure can emit light at a low voltage. Accordingly, a light-emitting element that can emit light at a low driving voltage can be obtained, and thus a light-emitting element with reduced power consumption can be obtained. Further, an element that becomes another light emission center may be included.

For example, as disclosed in JP-A-2005-336275, ZnS is used as a base material, Cu is used as a first impurity, Cl and Ga are used as a second impurity, As is used as a third impurity element, and It is also possible to use a light emitting material containing Mn as another light emitting center. In order to form such a light emitting material, the following method can be used. Mn is added to a phosphor (ZnS: Cu, Cl) in which copper sulfate (CuS), sulfur, and zinc oxide (ZnO) are blended with ZnS, and is fired in vacuum for about 2 to 4 hours. The firing temperature is preferably 700 to 1500 ° C. The fired product is pulverized to a particle size of 5 to 20 μm, GaAs having a particle size of 1 to 3 μm is added and stirred. A luminescent material can be obtained by baking this mixture at about 500 to 800 ° C. for 2 to 4 hours in a nitrogen stream containing sulfur gas. By using this luminescent material and forming a thin film by vapor deposition or the like, it can be used as a light emitting layer of a light emitting element.

Further, by adding an impurity element to the above light emitting material, the crystal system of the light emitting material can be controlled. Examples of impurities that can control the crystal system include cubic systems such as GaP, GaAs, GaSb, InP, InAs, InSb, Si, and Ge. Moreover, GaN and InN can be given as hexagonal ones. In addition, AlP, AlN, AlSb, or the like can be used. Luminous efficiency can be improved by controlling the crystal system of the light emitting material.

By using the light emitting material of this embodiment, the lighting devices of Embodiments 1 to 3 can be driven at a low voltage. It is also possible to cause the lighting device to emit light with a DC voltage.

In this embodiment, a structure of a light emitting unit and a light emitting cell using the light emitting unit will be described with reference to the drawings.

FIG. 7A illustrates a light-emitting cell in which the first electrode 12, the first light-emitting unit 14, the intermediate conductive layer 16, the second light-emitting unit 18, and the second electrode 20 are stacked. The light emitting cell can emit light by applying a voltage between the first electrode 12 and the second electrode 20.

For the first electrode 12, various metals, alloys, conductive compounds, mixtures thereof, and the like can be used. When the first electrode 12 is a transparent electrode, indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide (IZO), It is formed using indium tin oxide containing tungsten oxide and zinc oxide. These conductive metal oxide films can be produced by sputtering. For example, indium zinc oxide can be formed by sputtering using a target in which 1 to 20 wt% of zinc oxide is added to indium oxide. Further, indium oxide-tin oxide containing tungsten oxide and zinc oxide is formed by sputtering using a target containing 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide with respect to indium oxide. be able to. When the first electrode 12 is a metal electrode, aluminum (Al), silver (Ag), gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), titanium (Ti), titanium nitride (TiN), or the like can be used.

The second electrode 20 can be formed in the same manner as the first electrode 12. Since the second electrode 20 is formed in pairs with the first electrode 12, when one electrode is a transparent electrode, the other is formed by a metal electrode. Moreover, you may form both electrodes with a transparent electrode.

The first light emitting unit 14 and the second light emitting unit 18 are formed by the light emitting layer 201. This light-emitting layer 201 can be manufactured using the light-emitting material described in Example 4.

The intermediate conductive layer 16 forms an intermediate conductive layer and a second light emitting unit. The first light-emitting unit and the second light-emitting unit are typically formed using a base material containing a Group 12 and Group 15 element in the periodic table and one or a plurality of layers containing an impurity element that forms a light emission center. . The intermediate conductive layer is preferably formed of a transparent conductive film material such as indium oxide, indium tin oxide, zinc oxide, or indium zinc oxide. This is because the light emitted from the first light emitting unit and the second light emitting unit is effectively extracted. Another configuration of the intermediate conductive layer may be a configuration in which a hole generating layer and an electron generating layer are stacked.

The hole generating layer can be formed of a composite material of an inorganic compound and an organic compound. As a material for forming the hole generating layer, an inorganic compound is a substance that exhibits an electron accepting property with respect to an organic compound, and an organic compound is a substance that has an excellent hole transporting property. The inorganic compound is not particularly limited, but a transition metal oxide is preferable, and titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable. It is. In any case, it is desirable that the intermediate conductive layer 16 has as little absorption in the visible light region as possible.

As an organic compound, an aromatic amine compound represented by TDATA, MTDATA, m-MTDAB, TPD, NPB, DNTPD, TCTA, etc. as a material for the hole transport layer is a compound suitable for an organic compound because it easily generates holes. Is a group.

The electron generation layer only needs to include a layer having an electron-transporting organic compound and a substance that exhibits an electron-donating property for the organic compound. Examples of the electron-transporting organic compound include Alq ₃ , Almq ₃ , BeBq ₂ , BAlq, Zn (BOX) ₂ , Zn (BTZ) ₂ , BPhen, BCP, PBD, OXD-7, TPBI, TAZ, and p-EtTAZ. Can be used. In addition, examples of the substance exhibiting an electron donating property include alkali metals or alkaline earth metals such as lithium, magnesium, calcium, and barium, or alloys thereof. Alternatively, an alkali metal compound or an alkaline earth metal compound such as lithium oxide, barium oxide, lithium nitride, magnesium nitride, or calcium nitride can be used.

In any case, the intermediate conductive layer 16 sandwiched between the first light-emitting unit 14 and the second light-emitting unit 18 is applied to one side when a voltage is applied to the first electrode 12 and the second electrode 20. Any device that injects electrons into the light emitting unit and injects holes into the other light emitting unit may be used.

Although FIG. 7A illustrates a light-emitting element having two light-emitting units, the present invention can also be applied to a light-emitting element in which three or more light-emitting units are stacked. By connecting a plurality of light emitting units between the pair of electrodes with an intermediate conductive layer, it is possible to suppress deterioration while emitting light with high luminance while keeping the current density low.

FIG. 7B shows a structure in which the light emitting layer 201 and the barrier layer 202 are combined as the structure of the first light emitting unit 14 and the second light emitting unit 18. The barrier layer 202 is preferably disposed on the cathode side of the light emitting layer 201. The barrier layer 202 has a thickness of about 0.1 to 2 nm and is formed with a thickness through which a tunnel current flows. The barrier layer 202 can be formed using an insulating or semi-insulating metal oxide or metal nitride. For example, an oxide or nitride such as aluminum, tungsten, chromium, molybdenum, or titanium can be used. Such a thin film of metal oxide or metal nitride can be formed by a sputtering method. It can also be formed by anodizing the surface of the metal electrode.

By providing the barrier layer 202, carriers can be prevented from recombining at the interface between the electrode and the light-emitting layer. Moreover, since it becomes a barrier with respect to the carrier inject | poured into the light emitting layer, the probability that a carrier will not contribute to light emission and will flow into an electrode or an intermediate conductive layer as it is can be suppressed. With such a configuration, the light emission efficiency can be increased. FIG. 7B assumes a case where the first electrode 12 is an anode and the second electrode 20 is a cathode. When the first electrode 12 is a cathode and the second electrode 20 is an anode, the arrangement of the barrier layer 202 is reversed.

FIG. 7C shows a structure of the first light-emitting unit 14 and the second light-emitting unit 18 in which barrier layers 202 are provided on both sides of the light-emitting layer 201. The barrier layer 202 has a thickness of about 0.1 to 2 nm and is formed with a thickness through which a tunnel current flows. Thus, the same effect as in FIG. 7 can be obtained. In addition, when the barrier layer 202 is 10 nm to 1000 nm, light can be emitted by AC driving.

FIGS. 8A and 8B show a mode in which an organic-inorganic composite material layer is combined with a light-emitting layer formed of an inorganic material in order to enhance carrier injectability in a light-emitting cell. Also in this case, the light emitting cell includes the first electrode 12, the first light emitting unit 14, the intermediate conductive layer 16, the second light emitting unit 18, and the second electrode 20.

FIG. 8A shows a structure in which the light-emitting layer 201 and the organic-inorganic composite material layer 203 are combined as the structure of the first light-emitting unit 14 and the second light-emitting unit 18. The organic-inorganic composite material layer 203 is preferably provided on the anode side of the light-emitting layer 201 for injecting holes. FIG. 8A assumes a case where the first electrode 12 is an anode and the second electrode 20 is a cathode. In the case where the first electrode 12 is a cathode and the second electrode 20 is an anode, the arrangement of the organic-inorganic composite material layer 203 may be reversed.

The organic-inorganic composite material layer 203 is an organic-inorganic composite material formed by combining an organic compound and an inorganic compound. As an organic compound used for the organic-inorganic composite material, an aromatic amine compound, a carbazole derivative, an aromatic hydrocarbon, a high molecular compound (such as an oligomer, a dendrimer, or a polymer) can be used. Note that the organic compound used for the organic-inorganic composite material is preferably an organic compound having a high hole-transport property. Specifically, a substance having a hole mobility of 10 ⁻⁶ cm ² / V · sec or more is preferable. Note that other than these substances, any substance that has a property of transporting more holes than electrons can be used. Below, the organic compound which can be used for an organic inorganic composite material is illustrated.

As an aromatic amine compound, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB), 4,4′-bis [N- (3-methylphenyl)- N-phenylamino] biphenyl (abbreviation: TPD), 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [ N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA) can be given.

Moreover, the organic-inorganic composite material which does not have an absorption peak can be obtained in the wavelength range of 450 nm-800 nm by using the organic compound shown below. For example, N, N′-di (p-tolyl) -N, N′-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4′-bis [N- (4-diphenylaminophenyl) -N— Phenylamino] biphenyl (abbreviation: DPAB), 4,4′-bis (N- {4- [N- (3-methylphenyl) -N-phenylamino] phenyl} -N-phenylamino) biphenyl (abbreviation: DNTPD) ), 1,3,5-tris [N- (4-diphenylaminophenyl) -N-phenylamino] benzene (abbreviation: DPA3B), and the like.

Specific examples of the carbazole derivative include 3- [N- (9-phenylcarbazol-3-yl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis [N— (9-phenylcarbazol-3-yl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzPCA2), 3- [N- (1-naphthyl) -N- (9-phenylcarbazol-3-yl) Amino] -9-phenylcarbazole (abbreviation: PCzPCN1).

In addition, 4,4′-di (N-carbazolyl) biphenyl (abbreviation: CBP), 1,3,5-tris [4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB), 9- [4- ( N-carbazolyl)] phenyl-10-phenylanthracene (abbreviation: CzPA), 2,3,5,6-triphenyl-1,4-bis [4- (N-carbazolyl) phenyl] benzene, and the like can be used. .

In addition, 9,10-di (naphthalen-2-yl) -2-tert-butylanthracene is an aromatic hydrocarbon that can be used for an organic-inorganic composite material having no absorption peak in the wavelength region of 450 nm to 800 nm. (Abbreviation: t-BuDNA), 9,10-di (naphthalen-1-yl) -2-tert-butylanthracene, 9,10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 9, 10-di (4-phenylphenyl) -2-tert-butylanthracene (abbreviation: t-BuDBA), 9,10-di (naphthalen-2-yl) anthracene (abbreviation: DNA), 9,10-diphenylanthracene ( Abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-di (4 Methylnaphthalen-1-yl) anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis [2- (naphthalen-1-yl) phenyl] anthracene, 9,10-bis [2- (naphthalene- 1-yl) phenyl] anthracene, 2,3,6,7-tetramethyl-9,10-di (naphthalen-1-yl) anthracene, 2,3,6,7-tetramethyl-9,10-di ( Naphthalen-2-yl) anthracene, 9,9′-bianthryl, 10,10′-diphenyl-9,9′-bianthryl, 10,10′-di (2-phenylphenyl) -9,9′-bianthryl, 10 , 10′-bis [(2,3,4,5,6-pentaphenyl) phenyl] -9,9′-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11 And the like tetra (tert- butyl) perylene. In addition, pentacene, coronene, and the like can also be used. Thus, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 × 10 ⁻⁶ cm ² / V · sec or more and having 14 to 42 carbon atoms.

In the wavelength region of 450 nm to 800 nm, the aromatic hydrocarbon that can be used for the organic-inorganic composite material having no absorption peak may have a vinyl skeleton. As the aromatic hydrocarbon having a vinyl group, for example, 4,4′-bis (2,2-diphenylvinyl) biphenyl (abbreviation: DPVBi), 9,10-bis [4- (2,2- Diphenylvinyl) phenyl] anthracene (abbreviation: DPVPA).

A high molecular compound such as poly (N-vinylcarbazole) (abbreviation: PVK) or poly (4-vinyltriphenylamine) (abbreviation: PVTPA) can also be used.

As the inorganic compound used for the organic-inorganic composite material, a transition metal oxide is preferable. In addition, an oxide of a metal belonging to Groups 4 to 8 in the periodic table is preferable. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because of their high electron accepting properties. Among these, molybdenum oxide is a preferable material because it is stable in the air and its hygroscopic property is low so that it can be easily handled.

The organic-inorganic composite material obtained by combining the organic compound and the inorganic compound as described above (interacting with each other) is excellent in hole injecting property and hole transporting property. Also, the conductivity is high. Therefore, carriers can be easily injected from the electrode, and carriers can be efficiently transported to the light emitting layer. In addition, since it is possible to make ohmic contact with conductive metal oxides and various metals, a material for forming an electrode can be selected regardless of the work function. In addition, by using an organic-inorganic composite material that does not have an absorption peak in the wavelength region of 450 nm to 800 nm as the organic-inorganic composite material layer 203, the light is efficiently transmitted without absorbing light emitted from the light-emitting layer 201, and the external extraction efficiency is increased. Can be improved.

In addition, since a layer including an organic-inorganic composite material in which an organic compound and an inorganic compound are combined has high conductivity, an increase in driving voltage can be suppressed even when the layer including the organic-inorganic composite material is thickened. . Therefore, it is possible to optimize the thickness of the layer including the organic-inorganic composite material so that the efficiency of extracting light to the outside is increased while suppressing an increase in driving voltage. In addition, the color purity can be improved by optical design without increasing the driving voltage.

Note that any method may be used as a method for manufacturing the layer including the organic-inorganic composite material regardless of a wet method or a dry method. For example, the layer containing the organic-inorganic composite material can be manufactured by co-evaporation of the organic compound and the inorganic compound described above. Moreover, it can also obtain by apply | coating and baking the solution containing the organic compound and metal alkoxide which were mentioned above. Molybdenum oxide is easy to evaporate in a vacuum and is preferable from the viewpoint of the manufacturing process.

In this manner, by providing the organic-inorganic composite material layer 203 between the first electrode 12 (anode) and the light-emitting layer 201 or between the intermediate conductive layer 16 and the light-emitting layer 201, holes can be injected into the light-emitting layer. Can be improved. Since the base material for forming the light-emitting layer 201 is n-type, the carrier-injection property can be improved by combining the organic-inorganic composite material layer 203 that improves the hole-injection property. Accordingly, the lighting device can be turned on at a low voltage, and the light emission efficiency can be increased. That is, low power consumption can be achieved.

FIG. 8B illustrates a structure in which the organic-inorganic composite material layer 203 is provided on one surface of the light-emitting layer 201 and the barrier layer 202 is provided on the other surface. The barrier layer 202 can prevent carriers from recombining at the interface between the electrode and the light emitting layer. Moreover, since it becomes a barrier with respect to the carrier inject | poured into the light emitting layer, the probability that a carrier will not contribute to light emission and will flow into an electrode or an intermediate conductive layer as it is can be suppressed. Thus, by combining the organic-inorganic composite material layer 203 and the barrier layer 202, the light emission efficiency can be further increased.

The structure of the light emitting cell shown in this embodiment can be combined with the lighting devices of Embodiments 1 to 3.

With Embodiments 1 to 5, an aspect of a lighting device in which a plurality of light emitting cells are connected in series on a substrate will be described with reference to FIG. FIG. 9 shows a perspective view of the lighting device.

The substrate 10 has a light emitting cell array forming region 24 in which light emitting cells are connected in series. The structure of Examples 1 to 3 is applied to the series connection structure of the light emitting cells. Furthermore, in the aspect of the present embodiment, the light emitting cell array formation region 24 is divided into a plurality of substrates 10 on the substrate. By dividing the light emitting cell array formation region into a plurality on the substrate, the influence of resistance loss can be reduced by the electrodes even when the outer dimensions of the lighting device are increased. In addition, a brightness adjustment function can be added by providing a lighting circuit corresponding to an individual light emitting cell array formation region.

A diffusion plate 28 is provided on the light emitting surface of the substrate 10. The diffuser plate 28 has a function of making the light uniform and concealing the non-light emitting region (dark spot portion) of the light emitting cell array forming region 24 having a series connection structure inconspicuously. The sealing plate 26 is provided to protect the light emitting cell array formation region 24. The sealing plate 26 may be attached with a flexible flexible film in addition to a glass or plastic hard material. Further, when light is emitted to the sealing plate 26 side, it can be replaced with a diffusion plate. The sealing plate 26 is preferably attached so as to expose the extraction electrodes 30a, 30b, 32a, and 32b formed at the end portions of the substrate 10. In correspondence with the light emitting cell array, an extraction electrode 30a and an extraction electrode 32a, and an extraction electrode 30b and an extraction electrode 32b are provided.

The lighting device according to the present invention can form a light-emitting cell array in which light-emitting cells are connected in series with a thin film, so that a thin lighting device can be realized. The light emitting cell array described in Embodiments 1 to 5 can be formed with a thickness not exceeding 20 μm because each layer can be formed as a thin film. Therefore, even when used as lighting for a house, the lighting device can be embedded in the wall, ceiling, or floor without protruding. Of course, it can also be used as a backlight for a thin liquid crystal display.

This example illustrates various aspects of the lighting device according to the present invention.

FIG. 10 shows a mode in which the lighting device 303 is used as a backlight of a liquid crystal display device. The lighting device 303 has the same configuration as that described in Examples 1 to 6, and is characterized by being thin and having high light emission efficiency. The lighting device 303 is disposed on the back side (the side opposite to the display surface) of the liquid crystal panel 302 and is accommodated by the casings 301 and 304. A driver IC 305 or the like may be mounted on the liquid crystal panel 302.

The shapes of the housings 301 and 304 are changed into various shapes depending on applications. For example, in a consumer application such as a notebook personal computer or a liquid crystal television, the appearance is inconspicuous because the lighting device 303 is housed in a well-designed housing. However, since the lighting device 303 is thin, it can be easily accommodated in the housing. Thereby, the freedom degree of design design can be raised. In addition, a liquid crystal display device with high contrast can be provided by causing the lighting device 303 to emit light with high luminance. It can also contribute to lower power consumption.

FIG. 11 shows a television device 400, which includes a housing 401, a support base 402, a display portion 403, a speaker portion 404, and a video input terminal 405. In this television apparatus, the display unit 403 is a transmissive liquid crystal display, and includes a lighting device similar to that described in the first to sixth embodiments as a backlight. This illuminating device is characterized by high luminous efficiency and low driving voltage. It is also possible to prevent a short circuit due to an external impact or the like. Therefore, this television device is designed to reduce power consumption. With such a feature, in the television device, the power supply circuit can be significantly reduced or reduced, and the housing 401 and the support base 402 can be reduced in size and weight. As a result, a product suitable for the living environment can be provided.

FIG. 12 shows an example in which lighting devices similar to those described in Embodiments 1 to 6 are used as indoor lighting fixtures 501 and 502. The lighting fixture 501 is attached to the ceiling, and the lighting fixture 502 is shown as being embedded in a wall. The illuminating device according to the present invention can be increased in size, and uniform brightness can be obtained in the plane even when the size is increased. Furthermore, it is characterized by being thin and having low power consumption.

FIG. 13 illustrates a state where the lighting fixture 501 is attached to the ceiling. The luminaire 501 includes a substrate 10 on which a light emitting cell array is formed, a sealing plate 26, a mounting hinge 34, and a cover material 36. The extraction electrodes 30a and 30b of the illumination device are provided at the end of the substrate 10, and a part of the attachment hinge 34 is used as a connector. The cover material 36 has a light control function. Even if the lighting fixture 501 in which these elements are integrated is attached to the ceiling, it can be attached with hardly protruding from the ceiling surface as shown in FIG. Further, if the mounting hinge 34 is designed as a strong structural member, it can be embedded in the ceiling.

In this manner, a television set 400 described with reference to FIG. 11 can be installed in a room where the light-emitting device to which the present invention is applied is used as indoor lighting fixtures 501 and 502, and public broadcasting and movies can be watched. In such a case, since the lighting fixtures 501 and 502 and the television set 400 both have low power consumption, powerful images can be viewed in a bright room without worrying about the electricity bill.

The lighting device is not limited to the one exemplified in this embodiment, and can be applied as various types of lighting devices including lighting of houses and public facilities. In such a case, since the illuminating device according to the present invention has a thin light emitting medium and has a high degree of design freedom, various products can be provided to the market.

1 is a cross-sectional view illustrating a configuration of a lighting device according to Embodiment 1. FIG. FIG. 3 is a plan view illustrating a configuration of a lighting device according to the first embodiment. Sectional drawing which shows the structure of the illuminating device which concerns on Example 2. FIG. FIG. 6 is a plan view illustrating a configuration of a lighting device according to a second embodiment. Sectional drawing which shows the structure of the illuminating device which concerns on Example 3. FIG. FIG. 6 is a plan view illustrating a configuration of a lighting device according to a third embodiment. The figure which shows the light emitting cell by which the 1st electrode, the 1st light emission unit, the intermediate | middle conductive layer, the 2nd light emission unit, and the 2nd electrode were laminated | stacked. The figure which shows the light emitting cell by which the 1st electrode, the 1st light emission unit, the intermediate | middle conductive layer, the 2nd light emission unit, and the 2nd electrode were laminated | stacked. The perspective view which shows the structure of an illuminating device. The figure which shows the aspect which uses an illuminating device as a backlight of a liquid crystal display device. The figure which shows an example of the electric appliance using an illuminating device. The figure which shows an example of an illuminating device. The figure which shows the attachment structure of the illuminating device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 12 1st electrode 12a 1st electrode 12b 1st electrode 12c 1st electrode 13a 1st opening part 13b 1st opening part 13c 1st opening part 13d 1st opening part 14 1st opening part Light emitting unit 14a First light emitting unit 14b First light emitting unit 14c First light emitting unit 16 Intermediate conductive layer 16a Intermediate conductive layer 16b Intermediate conductive layer 16c Intermediate conductive layer 18 Second light emitting unit 18a Second light emitting unit 18b Second light emitting unit 18c second light emitting unit 19a second opening 19b second opening 19c second opening 20 second electrode 20a second electrode 20b second electrode 20c second electrode 20d second Second electrode 21a Third opening 21b Third opening 21c Third opening 24 Light emitting cell array formation region 26 Sealing plate 28 Diffusion plate 30a Extraction electrode 0b Extraction electrode 32a Extraction electrode 32b Extraction electrode 34 Mounting hinge 36 Cover material 101 First light emitting cell 102 Second light emitting cell 103 Third light emitting cell 201 Light emitting layer 202 Barrier layer 203 Organic / inorganic composite material layer 301 Housing 302 Liquid crystal Panel 303 Lighting device 304 Housing 305 Driver IC
400 Television apparatus 401 Housing 402 Support base 403 Display unit 404 Speaker unit 405 Video input terminal 501 Lighting fixture 502 Lighting fixture

Claims (14)

A plurality of light emitting units each having at least one light emitting layer are connected in series between a pair of electrodes, and an intermediate conductive layer is provided between one light emitting unit and another light emitting unit in the series connection relationship. Have multiple cells,
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer. On the board
A plurality of light emitting units each having at least one light emitting layer are connected in series between a pair of electrodes, and an intermediate conductive layer is provided between one light emitting unit and another light emitting unit in the series connection relationship. Have multiple cells,
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer, and is on the inner side not reaching an end portion of the substrate. A plurality of light emitting units having at least one light emitting layer are connected in series between a pair of electrodes, and an end portion of the light emitting unit is provided between one light emitting unit and another light emitting unit in the series connection relationship. Having a plurality of light emitting cells provided with an intermediate conductive layer on the inner side not reaching
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer. On the board
A plurality of light emitting units having at least one light emitting layer are connected in series between a pair of electrodes, and an end portion of the light emitting unit is provided between one light emitting unit and another light emitting unit in the series connection relationship. Having a plurality of light emitting cells provided with an intermediate conductive layer on the inner side not reaching
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer, and is on the inner side not reaching an end portion of the substrate. A plurality of light emitting units having at least one light emitting layer are connected in series between a pair of electrodes, and between one light emitting unit and another light emitting unit in the series connection relationship,
A plurality of light emitting cells provided with intermediate conductive layers whose ends are covered with the light emitting unit;
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer. On the board
A plurality of light emitting units having at least one light emitting layer are connected in series between a pair of electrodes, and between one light emitting unit and another light emitting unit in the series connection relationship,
A plurality of light emitting cells provided with intermediate conductive layers whose ends are covered with the light emitting unit;
One electrode and the other electrode of the pair of electrodes have an electrical connection portion connected in series between different light emitting cells,
The electrical connection portion is formed by an opening that exposes one or the other electrode formed on a lower layer side of the light emitting layer, and is on the inner side not reaching an end portion of the substrate. In any one of Claims 1 thru | or 6,
The light emitting layer includes a base material that is a compound including a Group 2 element and a Group 16 element or a Group 12 element and a Group 16 element, and an impurity element that is a light emission center. A lighting device. In claim 7,
The base material is zinc sulfide, cadmium sulfide, calcium sulfide, yttrium sulfide, gallium sulfide, strontium sulfide, barium sulfide, zinc oxide, yttrium oxide, aluminum nitride, gallium nitride, indium nitride, zinc selenide, zinc telluride, sulfide A lighting device characterized by being one of calcium-gallium, strontium sulfide-gallium, and barium sulfide-gallium. In claim 7,
The illuminating device, wherein the impurity element is a metal element that becomes a light emission center. In claim 7,
The impurity element includes a plurality of types,
A metal element that becomes the emission center;
Any one of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl);
Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) A lighting device characterized by being one of them. In claim 9 or 10,
The lighting device according to claim 1, wherein the metal element is contained at a concentration of 0.05 to 5 atomic% with respect to the base material. In claim 7,
The impurity element includes a plurality of kinds, and any one of copper, silver, gold, platinum, silicon,
A lighting device, which is any one of fluorine, chlorine, bromine, iodine, boron, aluminum, gallium, indium, and thallium. In claim 7,
The impurity element includes a plurality of kinds, and any one of copper, silver, gold, platinum, silicon,
A lighting device characterized by being any one of lithium, sodium, potassium, rubidium, cesium, nitrogen, phosphorus, arsenic, antimony, and bismuth. In claim 7,
The impurity element includes a plurality of kinds, and any one of copper, silver, gold, platinum, silicon,
Any one of fluorine, chlorine, bromine, iodine, boron, aluminum, gallium, indium, and thallium;
A lighting device characterized by being any one of lithium, sodium, potassium, rubidium, cesium, nitrogen, phosphorus, arsenic, antimony, and bismuth.

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