JP2002313570A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element that can change a luminous color tone without needing a plurality of signal lines for every picture element. SOLUTION: Organic EL laminated bodies 3a, 3b of this organic EL element 1A are arranged to be visible as a square picture element as a whole. When the luminous layers of organic EL films used for the organic EL element 1A emit light of the same brightness, the resistance of the organic EL film 32b is higher than that of the organic EL film 32a at first, but when driven for a long time, the resistance of the organic EL film 32a becomes higher than that of the organic EL film 32b. In such an organic EL element, it is not necessary to add the signal line for changing the color tone, and the luminous color tone can be changed using a driving circuit of the conventional organic EL element as it is. Furthermore, the composition of the organic EL films can be easily determined from the color tone required for operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an organic EL (electroluminescence) element, and more particularly, to a method of changing a color tone to be emitted under specific conditions without requiring a plurality of signal lines for each pixel. The present invention relates to a possible organic EL device.

[0002]

2. Description of the Related Art The color of an organic EL element that emits light by passing a current through an organic EL laminate having electrodes provided on the organic EL film is uniquely determined by a commonly used organic EL film. Therefore, when it is desired to represent a plurality of color tones, a plurality of types of organic E
The color tone was changed by preparing the L laminated body and controlling the light emission individually.

[0003]

However, the organic EL element for individually controlling light emission requires extra wiring and a control circuit for controlling each organic EL laminate as compared with one type of color tone display. In some cases, it is necessary to use a simple color tone change which requires only a few steps such as a warning display of an abnormal temperature. In addition, a conjugated polymer and a fluorescent low-molecular compound are used for the light emitting layer, and an organic E that can change the color tone by changing the applied voltage.
The L element is disclosed in JP-A-6-342690. However, since a conjugated polymer and a fluorescent low-molecular compound are mixed to form one organic EL laminate, it has been difficult to obtain a composition that emits a necessary color tone. An object of the present invention is to solve such a problem, and an object of the present invention is to provide an organic EL element capable of changing a color tone to be emitted without requiring a plurality of signal lines for each pixel. .

[0004]

According to the first aspect of the present invention, there is provided an organic EL device comprising: a substrate; and two or more organic EL devices provided on the substrate.
An organic EL device comprising: a laminate;
The laminate includes an anode, an organic EL film, and a cathode that are sequentially laminated, and can be viewed as one pixel by performing a parallel arrangement and / or a stacking arrangement, and the anode and the cathode of each organic EL laminate are Light emission is controlled by a pair of signal lines,
Each of the organic EL films in each of the organic EL laminates is characterized in that the driving time, the temperature of the organic EL film, and the light emission characteristics of the luminance and / or the color tone with respect to at least one of the applied currents are different from each other.

[0005] The "parallel arrangement" means that the above-mentioned "organic EL laminates" are arranged side by side in the shape of a pixel and are arranged on a substrate. In addition, the above "stacked arrangement"
Means that the organic EL laminates are stacked on top of each other and disposed on a substrate. Further, the organic EL laminates may be arranged side by side so as to partially overlap each other, or may be pixels arranged in a parallel arrangement and a stacked arrangement.

[0006] The above "each organic EL laminate can be visually recognized as one pixel" is constituted by arranging or stacking two or more organic EL laminates on a substrate to constitute one pixel. This means that one pixel is not substantially seen as a plurality of pixels.

[0007] The above-mentioned "the anode and the cathode of each organic EL laminate are controlled by a set of signal lines to emit light" means that these anodes and cathodes are connected in an arbitrary form, and each organic EL laminate is individually connected. Light emission is controlled by a single control using a set of signal lines without control. Further, as shown in the second invention, in each of the organic EL laminates, the anode and the cathode are connected in series and / or in parallel, so that light emission is controlled by a set of signal lines. can do. Furthermore, a resistor or the like for adjusting the luminance of each organic EL laminate may be inserted and connected.

Further, the respective organic EL laminates may be connected directly or indirectly using lead wires or the like.
Further, in the case of direct connection, the anodes and cathodes of each organic EL laminate can be made common,
When the L laminates are connected in series, the anode and the cathode connected in series may be common.

"Each of the organic EL films of each of the organic EL laminates has (1) a driving time, (2) a temperature of the organic EL film, and (3) a luminance and / or color tone emission characteristic with respect to an applied current. "Is different from each other" means that each organic EL film constituting one pixel has a light emission characteristic such that a different color tone is obtained as a whole by changing the conditions shown in the above (1) to (3). .

The conditions (1) to (3) will be described in detail below. (1) Driving time The “driving time” is the time during which the organic EL laminate has been driven so far. The organic EL laminate has light emission characteristics in which the luminance changes due to the change in the resistance of the organic EL film depending on the driving time. Since the light emission characteristics with respect to the drive time vary depending on the configuration of the organic EL film, by combining two or more organic EL laminates provided with organic EL films having different light emission characteristics with respect to the luminance, the luminance of each emitted light can be varied depending on the arbitrary drive time. Each has a different ratio, and can provide a different color tone as a pixel. Incidentally, by changing the composition of the film constituting the organic EL film, the structure itself, and the like, the organic EL film can be formed.
Changing the light emission characteristics of the film can be exemplified.

(2) Temperature of Organic EL Film Generally, when the temperature of the organic EL film is high, the resistance of the organic EL film decreases and the luminance changes under the same driving conditions. Can be seen. This organic E
Since the luminescence characteristics of the L film with respect to the temperature vary depending on the configuration of the organic EL film, the luminescence characteristics of the L film with respect to the temperature are different.
By combining two or more organic EL laminates each having a film, the luminance of each emitted light has a different ratio depending on the temperature of the organic EL film, and a different color tone can be provided as a pixel. Note that the temperature of the organic EL film is
Since the color tone changes depending on the ambient temperature of the element, the color tone can be changed by the ambient temperature change. Further, the color tone can be changed by the heat generation of the organic EL film due to the light emission, so that the color tone can be changed by controlling the heat generation of the organic EL film.

(3) Applied Current Since the resistance of the organic EL film is usually changed by an applied current for emitting light, the organic EL laminate exhibits light emission characteristics in which the luminance changes under the same driving conditions. Since the light emission characteristics with respect to the applied current vary depending on the configuration of the organic EL film, the luminance of each light emitted is changed by the applied current by combining two or more organic EL laminates each having an organic EL film having a different light emission characteristic with respect to the applied current. Each has a different ratio, and can provide a different color tone as a pixel.

The "organic EL element" may be composed of only one pixel, or may be composed of two or more pixels. The shape of the pixel is not particularly limited, and may be a shape suitable for an arrangement such as a rectangle or a circle, or may be an arbitrary design figure.

The “organic EL film” constituting the “organic EL laminate” is a portion that emits light by recombining holes and electrons supplied from the anode and the cathode. This organic EL film includes a light emitting layer containing at least an organic fluorescent substance. In addition, at least one of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer can be provided in addition to the light emitting layer. Further, various known materials can be used as a material constituting each layer. As a method of forming each of these layers, a vacuum evaporation method, a spin coating method, a casting method, a sputtering method,
The LB method can be used. The light-emitting layer constituting the organic EL film can be formed of a benzothiazole-based or benzimidazole-based fluorescent whitening agent, a metal chelated oxinoid compound, a metal complex such as a styrylbenzene-based compound, or the like. Further, by using a mixture of a conjugated polymer and a fluorescent low-molecular compound as disclosed in JP-A-6-342690 for the light-emitting layer, a light-emitting layer whose color tone changes according to an applied voltage may be used. In addition, the organic EL film having such a light emitting layer is described in the above (1) to (1).
It is expected that the color tone changes also under the condition shown in (3). Depending on certain conditions, all the organic EL films emit light in the same color, but in other conditions light emits in different colors.
An organic EL element whose color tone changes as a whole can be obtained. Further, the hole transport layer can be formed by a triphenylamine derivative or the like, and the electron transport layer can be formed by an aluminum quinolium complex or the like. The hole injection layer can be formed of a copper phthalocyanine complex or the like, and the electron injection layer can be formed of an alkali metal fluoride or oxide.

The above "anode" and "cathode" can also be formed of various materials.
The anode is made of a single metal such as Au or Ni, and ITO (Indium).
It can be formed using a metal compound such as Tin Oxide), CuI, SnO2, and ZnO. Among these, it is preferable to use ITO from the viewpoint of stable conductivity and productivity. The cathode is made of Al, Au, A
g, Mg, other metals such as Cu, alloys such as Mg-Ag,
It can be formed of a mixture of Mg and Ag. Further, ITO or the like can be used. It does not matter whether the anode or the cathode is in contact with the substrate.

The "substrate" may be any material as long as it can form an organic EL film constituting an organic EL laminate on its surface, and can be arbitrarily selected. Also, there is no particular limitation on whether the material is transparent. Further, in the case of a transparent substrate, a substrate made of a material having such transparency as not to impair the recognition of characters, figures and the like by light emission of the organic EL film can be used. As such a substrate, a substrate made of inorganic glass, polyolefin, polyester, polyamide, polycarbonate, acrylic resin, or the like can be used. The transparent substrate may be colorless and transparent, or may be a colored and transparent substrate colored in an appropriate color tone. Further, the present organic EL element can be provided with a sealing member for sealing the organic EL laminate.
The sealing member has a joining surface that is joined to the substrate at the periphery thereof, and other portions include the sealing member, the anode,
It is preferable that the cap has a shape in which a space is formed so as not to contact the organic EL laminate including the organic EL film and the cathode.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an organic EL device of the present invention will be described with reference to examples with reference to FIGS. Example 1 Example 1 relates to an organic EL element 1A in which organic EL laminates are arranged in parallel, and the color tone of light emission can be visually recognized so as to change depending on the driving time. (1) Configuration of Organic EL Element As shown in FIGS. 1 and 2, an organic EL element 1A according to the first embodiment includes a transparent glass substrate 2 and an anode 31a formed on the substrate 2 in order. 31b, organic EL film 32a,
The organic EL device includes an organic EL laminate 3a, 3b composed of 32b and cathodes 33a, 33b, an anode 31, a cathode 33, and a partition wall 41.

The anodes 31a and 31b are made of an ITO thin film, and as shown in FIG. 1 (3), the anode 31, the anode 31a and the anode 31b are disposed integrally on a substrate. The organic EL films 32a and 32b are made of an organic fluorescent material or the like, and a hole injection layer made of a copper phthalocyanine complex, a hole transport layer made of TPTE (a tetramer of triphenylamine) in order from the anodes 31a and 31b, It is a thin film formed by sequentially laminating layers such as a light emitting layer, an electron transport layer made of an aluminum quinolium complex, and an electron injection layer made of LiF. Further, as shown in FIG. 1B, the organic EL film 32b
Is a square shape, and the organic EL film 32a is a square shape excluding the portion of the organic EL film 32b. The light emitting layer is made of an organic EL
In the film 32a, a quinolinol aluminum complex doped with dimethylquinacridone is used so that the emission color becomes green. In the organic EL film 32b, an additive for red emission is added to the quinolinol aluminum complex so that the emission color becomes red. Is used. These light emitting layers are
As shown in FIG. 3, the brightness and the temperature are constant (40 in FIG. 3).
0 cd / m ² , 85 ° C.).

The cathodes 33a and 33b are made of an Al thin film, and as shown in FIG.
1b are integrally disposed on the substrate. Anode 31
The cathode 33 is a terminal provided by extending one end of the anode 31a and the cathode 33a to the end of the substrate 2 as shown in FIG.

As shown in FIG. 1, the organic EL laminates 3a and 3b are arranged around the square organic EL laminate 3b.
By providing a hollow and square organic EL laminate 3a, the arrangement is such that the pixel is viewed as a square pixel as a whole. This is when you look at the distance you normally use,
Each light emitted from the two organic EL laminates 3a and 3b cannot be distinguished. Further, the organic EL laminates 3a, 3
The boundary of b is partitioned by the partition 41 and the anode 31 is formed by the wiring 6 at the position where the partition 41 is interrupted.
a, 31b and cathodes 33a, 33b are respectively connected in parallel. The size and the ratio of the organic EL laminates 3a and 3b are such that they cannot be easily distinguished from each other even if both emit light. Further, by appropriately adjusting the surface area occupied by the organic EL laminates 3a and 3b on the substrate and the width of the wiring 6 in the parallel connection portion between the organic EL laminates 3a and 3b,
The brightness of the light emitted by the laminates 3a and 3b is adjusted so that the color becomes yellow when the driving time shown in FIG. 3 is about 800 hours.

(2) Effect of Organic EL Element The present organic EL element 1A is disposed in parallel on the substrate 2 as shown in FIGS. 1 and 2, and has an electrode connected in parallel.
As shown in FIG. 1 (1), the organic EL laminate 3 is provided by passing a current through the anodes 31a, 32b and the cathodes 33a, 33b via the anode 31 and the cathode 33, as shown in FIG.
Both a and 3b emit green and red light, and can be visually recognized as light in which both colors are combined. In addition, this organic EL
When the light emitting layer of the organic EL film used for the element 1A emits the same luminance as shown in FIG.
Although the organic EL film 32b has a higher resistance than the organic EL film 2a, about 8
After 00 hours, the organic EL film 32a is
The resistance becomes higher than b. Therefore, when the applied current is constant, the color emitted from the organic EL element 1A (yellow color) is initially yellow-green due to the high brightness of the organic EL film 32a, but the driving time is about 800 hours. , And then becomes red because the luminance of the organic EL film 32b increases.

The color tone of such an organic EL element 1A can be changed by using a conventional light emitting method of an organic EL element, and the color tone does not return even if the energization is stopped and the light is turned off halfway. When the life has expired, various timed displays such as a red display can be performed. Further, it is not necessary to add a signal line for changing a color tone, and a conventional drive circuit of organic EL elements, wiring and a connector for connection can be used as it is. Further, the change in the color tone due to the driving time of the organic EL element 1A is the same as that of the organic EL element 1A.
It can be easily determined from the color tone and luminance obtained from the light emission characteristics of the L film. Therefore, the composition and the like of the organic EL film to be used can be easily determined from the color tone required for the implementation.

Embodiment 2 The present embodiment 2 relates to an organic EL element 1B in which organic EL laminates are stacked and arranged so that the color tone of light emission changes as the temperature of the organic EL film changes. . (1) Configuration of Organic EL Element The organic EL element 1B of Example 2 has a structure as shown in FIG.
Transparent glass substrate 2, anode 31a, organic EL film 3
An organic EL laminate 3a comprising a cathode 2a and an cathode 33a, an insulating layer 5, an anode 31b, an organic EL film 32b and a cathode 33
b) of the organic EL laminate 3b. An organic EL laminate 3a, an insulating layer 5, and an organic EL
The L laminated body 3b is formed vertically in this order.

The anodes 31a and 31b and the cathode 33a are made of an ITO thin film capable of transmitting light from the substrate 2 side. The cathode 33b is made of an Al thin film. The anodes 31a and 31b and the cathodes 33a and 33b are connected in parallel (not shown). Further, the organic EL film 32
Reference numerals a and 32b denote a thin film formed of an organic fluorescent material or the like as in Example 1, and formed by sequentially stacking layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. It is. The light emitting layer uses an organic fluorescent material that emits green light in the organic EL film 32a, and an organic fluorescent material that emits red light in the organic EL film 32b.
In the L element 1B, the organic EL film 32 as illustrated in FIG.
A composition having luminance characteristics with respect to the temperatures of a and 32b was used.

(2) Effect of Organic EL Element The present organic EL element 1B is provided with organic EL laminates 3a and 3b stacked on a substrate as shown in FIG. , 32b and cathode 33
When the current is passed through a and 33b, both of the two organic EL laminates 3a and 3b emit green and red light, and when viewed from the substrate 2 side, both colors can be visually recognized as combined light.

The organic EL device used in the organic EL device 1B
As shown in FIG. 5, when the temperature of the organic EL film is low, the organic EL film 32a has higher luminance than the organic EL film 32b, but the organic EL film 32b has higher luminance at high temperatures. The brightness becomes higher than that of the EL film 32a. Therefore, organic E
The color (color seen as a pixel) emitted by the L element 1B is yellow-green at a low temperature because the luminance of the organic EL film 32a is high, but becomes red at a high temperature because the luminance of the organic EL film 32b is high. Further, the temperature of the organic EL films 32a and 32b affects the temperature of the atmosphere of the organic EL element 1B. Such an organic EL element 1B can change the color tone depending on the ambient temperature even by using a normal organic EL element light emitting method,
Temperature display by color tone can be performed. Furthermore, organic E
The color tone can be changed by controlling the heat generation of the L films 32a and 32b, and the temperature can be displayed by the color tone.

Further, the organic EL device 1B of Example 2
Similar to the organic EL element 1A of the first embodiment, there is no need to add a signal line for changing the color tone, and the conventional organic EL element 1A is used.
The drive circuit of the L element, the wiring, the connector for connection, and the like can be used as they are. Further, the organic EL element 1
The necessary composition of the organic EL film and the like can be easily determined from the color tone required for the execution of B.

Embodiment 3 The present embodiment 3 relates to an organic EL element 1C in which organic EL laminates are stacked and arranged so that the color tone can be visually recognized so as to change with an applied current. (1) Configuration of Organic EL Element As shown in FIG.
A transparent glass substrate 2, an organic EL laminate 3 a composed of an anode 31 a, an organic EL film 32 a, and a cathode 33 a sequentially formed on the substrate 2; an insulating layer 5;
b, an organic EL comprising an organic EL film 32b and a cathode 33b
And a laminate 3b.

Anodes 31a, 31b and cathodes 33a, 33
“b” has the same configuration as that of the organic EL element 1B of Example 2. Further, the organic EL films 32a and 32b are also made of an organic fluorescent material or the like in the same manner as in the second embodiment, and each layer such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are sequentially laminated. It is a thin film composed of Also, the light emitting layer is
In the organic EL film 32a, an organic fluorescent material emitting green light is used, and in the organic EL film 32b, an organic fluorescent material emitting red light is used. In the organic EL element 1C, the organic EL laminate 3a illustrated in FIG. And a composition having luminance characteristics with respect to the applied current of 3b.

(2) Effects of Organic EL Element The present organic EL element 1C includes stacked organic EL laminates 3a and 3b and anodes 31a and 32b, as in Example 2.
By passing a current through the cathodes 33a and 33b, when viewed from the substrate 2 side, both colors can be visually recognized as combined light.
As shown in FIG. 6, in the light emitting layer of the organic EL film used in the organic EL element 1C, when the applied current of the organic EL film is small, the organic EL film 32a has higher luminance than the organic EL film 32b. However, at a large current, the luminance of the organic EL film 32b is higher than that of the organic EL film 32a. Therefore, organic EL
The color (color seen as a pixel) emitted by the element 1C is yellow-green at a small current because the luminance of the organic EL film 32a is high, but becomes red at a large current because the luminance of the organic EL film 32b is high. Such an organic EL element 1B can use a conventional organic EL element drive circuit, change the color tone by changing the applied current, and perform various displays such as a warning when the gasoline level is low. Can be.

Further, in the organic EL element 1C of the third embodiment, similarly to the organic EL elements 1A and 1B, the conventional drive circuit, wiring and connectors for the organic EL element can be used as they are. It is possible to easily determine the required composition of the organic EL film and the like.

The present invention is not limited to the above embodiment, but may be variously modified within the scope of the present invention according to the purpose and application. That is, the configuration of the organic EL element 1A of each embodiment 1 is changed to the organic EL element of the embodiment 2 shown in FIG.
As in the case of the elements 1B and 1C, the organic EL laminates 3a and 3a
b can be stacked and used. Further, each embodiment 2
The configuration of the organic EL elements 1B and 1C is the same as that of the organic EL element 1A of the first embodiment shown in FIGS.
The laminates 3a and 3b can be used side by side. Furthermore,
The organic EL laminates 3a and 3b of the organic EL elements 1A to 1C of Examples 1 and 2 can be used side by side so as to partially overlap.

The number of organic EL laminates in Examples 1 and 2 is not limited to two, and three or more organic EL laminates may be used in parallel and / or stacked to obtain a more complicated change in color tone. Can be. Further, the shape of the pixel is not limited to the square shape of the first embodiment shown in FIG. 1, but may be a circular shape or an arbitrary design figure. In the case where the organic EL laminates are used side by side, the organic EL laminate 3a is not limited to the mode in which the organic EL laminate 3a is arranged so as to surround the one organic EL laminate 3b shown in FIG. It may be a dissimilar figure (for example, a combination of a rectangle and a triangle). Further, as the organic EL film to be used, not only the one that changes the luminance as shown in each embodiment but also the one that changes the color tone can be used.

[0034]

According to the organic EL device of the present invention, it is not necessary to add a signal line for changing the color tone, and the color tone to be emitted can be changed by directly using the conventional organic EL element driving circuit and the like. Can be done. Further, the composition of the organic EL film can be easily determined from the color tone required for the implementation.

[Brief description of the drawings]

FIG. 1 is a (1) plan view, (2) a plan view showing an organic EL film shape, and (3) a plan view showing an anode shape for explaining the configuration of an organic EL element of Example 1.

FIG. 2 is a partial cross-sectional view taken along line XX in FIG. 1A for explaining the configuration of the organic EL element of the first embodiment.

FIG. 3 is a graph for explaining a change in light emission luminance with time of each organic EL laminate of the organic EL element of Example 1.

FIG. 4 is a longitudinal sectional view for explaining the configuration of the organic EL elements of Examples 2 and 3.

FIG. 5 is a graph showing an example of a change in light emission luminance with a change in the temperature of the organic EL film when the applied current is constant in each organic EL laminate of the organic EL element of Example 2.

FIG. 6 is a graph illustrating a change in light emission luminance with a change in applied current in each organic EL laminate of the organic EL element of Example 3.

[Explanation of symbols]

1; organic EL element, 2; substrate, 3a, 3b; organic EL laminate, 31, 31a, 31b; anode, 32a, 32b;
Organic EL films, 33, 33a, 33b; cathode, 41; partition walls, 5; insulating layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/26 H05B 33/26 Z

Claims (2)

[Claims] 1. An organic EL device comprising a substrate and two or more organic EL laminates provided on the substrate, wherein each of the organic EL laminates includes an anode, an organic EL
The organic EL device includes a film and a cathode, and can be viewed as one pixel by performing a parallel arrangement and / or a stacking arrangement. The anode and the cathode of each of the organic EL laminates are controlled to emit light by a set of signal lines. An organic EL device, wherein each of the organic EL films of the organic EL laminate has different emission characteristics of luminance and / or color tone with respect to at least one of a driving time, a temperature of the organic EL film, and an applied current. 2. The organic EL device according to claim 1, wherein in each of the organic EL laminates, the anode and the cathode are connected in series and / or in parallel, so that light emission is controlled by a set of signal lines. .