JP2017112011A - Organic electroluminescent element, and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element capable of controlling the light distribution characteristics of each light-emitting unit.SOLUTION: An organic electroluminescent element has a first light-emitting unit, and a second light-emitting unit emitting light of wavelength different from that of the first light-emitting unit, where the angle θ1 at which the emission intensity of the first light-emitting unit is maximum, and the angle θ2 at which the emission intensity of the second light-emitting unit is maximum, measured from the front direction, satisfy the following relation; (15°≤|θ1-θ2|≤75° (where, 0°≤θ1, θ2<90°)).SELECTED DRAWING: Figure 2

Description

  The present invention relates to an organic electroluminescent element and a light emitting device including the organic electroluminescent element. More specifically, the present invention relates to a toned organic electroluminescence element and a light emitting device.

  An organic electroluminescence (EL) element is self-luminous and can be reduced in thickness, power consumption is reduced, and response speed is high.

  In lighting applications, if the light emission color of the organic EL element can be changed, a color effect can be obtained effectively. For this reason, the toning function capable of changing the emission color in the organic EL element can be an important function. As one form of such a toning function, a display device in which a toning (dimming) unit is provided in an organic EL element has been proposed (see, for example, Patent Document 1).

JP 2009-99400 A

  In recent years, in illumination and the like, there has been a demand for an organic EL element that changes in color according to the viewing angle, in addition to the above-described toning function. In such an organic EL element whose color changes according to the viewing angle, it is necessary to control the light distribution characteristics for each light emitting unit.

  In order to solve the above-described problems, the present invention provides an organic electroluminescence element capable of controlling the light distribution characteristics of each light emitting unit.

The organic electroluminescence device of the present invention is an organic electroluminescence device comprising two or more layers of light emitting units and three or more layers of electrodes sandwiching the light emitting units, and is different from the first light emitting units and the first light emitting units. An angle θ1 at which the light emission intensity of the first light emitting unit is maximized, and an angle θ2 at which the light emission intensity of the second light emitting unit is maximized, as measured from the front direction. Satisfies [15 ° ≦ | θ1−θ2 | ≦ 75 ° (where 0 ° ≦ θ1, θ2 <90 °)].
Moreover, the light-emitting device of this invention is equipped with the said organic electroluminescent element.

  ADVANTAGE OF THE INVENTION According to this invention, the organic EL element which can control the light distribution characteristic for every light emission unit can be provided.

It is a figure which shows the angle dependence of the light discharge | released from a light emission unit. It is a figure which shows the specific structure of the organic EL element for demonstrating the design method. It is a figure for demonstrating the conditions in which a phase is strengthened in an organic EL element. It is a figure for demonstrating the conditions in which a phase is strengthened in an organic EL element. It is a figure which shows the structure of the organic EL element of embodiment.

Hereinafter, although the example of the form for implementing this invention is demonstrated, this invention is not limited to the following examples.
The description will be given in the following order.
1. 1. Outline of organic electroluminescence device Embodiment of organic electroluminescence device

<1. Embodiment of Semiconductor Device>
Prior to specific embodiments of the organic electroluminescence (EL) element, an outline of the organic EL element of the present invention will be described.

  In general, an organic EL element provided with a plurality of light emitting units and emitting light of different colors (wavelengths) from each light emitting unit is affected by a microcavity (microresonator) effect. In the microcavity effect, by adjusting the thickness of the light emitting unit, the light of a specific wavelength is emphasized by resonating between the electrodes (cathode / anode), the light of other wavelengths is weakened, and the light extracted outside The spectrum can be steep and high intensity.

  Further, due to the microcavity effect, different angle dependence is given to the light intensity of the wavelength emitted from each light emitting unit. That is, the light emitting unit is given individual light distribution characteristics by the microcavity effect. For example, in an organic EL element having a first light emitting unit and a second light emitting unit, the emission intensity of light (L1) emitted from the first light emitting unit is centered on 0 ° in the front direction of the organic EL element. The light intensity of the light (L2) emitted from the second light emitting unit can be improved in a specific range (within an angle) at an angle outside the angle at which the light (L1) is enhanced. By adopting a configuration that provides such light distribution characteristics, the light (L1) emitted from the first light emitting unit is visually recognized in the front direction of the organic EL element, and the second light emitting unit is formed at an angle outside this. The light (L2) emitted from is visually recognized. Accordingly, by stacking a plurality of light emitting units that emit light of different wavelengths and controlling the light distribution characteristics given by the microcavity effect for each light emitting unit, it is possible to configure an organic EL element whose color tone changes depending on the viewing angle. it can.

  Specifically, in an organic EL element having a first light emitting unit and a second light emitting unit, an angle at which the light emission intensity of light (L1) emitted from the first light emitting unit is maximum (maximum intensity angle: θ1), When a difference of 15 ° or more is provided to the angle (maximum intensity angle: θ2) at which the light emission intensity of the light (L2) emitted by the second light emitting unit is maximized, the light (L1) and the light (L2) are Each can be viewed at different angles. That is, in the front direction of the organic EL element, the light distribution characteristic of the organic EL element is controlled so that the light (L1) and the light (L2) satisfy the relationship of [| θ1−θ2 | ≧ 15 °]. An organic EL element in which different colors are visually recognized according to the viewing angle can be configured.

  Even when the maximum intensity angles θ1 and θ2 are designed, the light L1 and the light L2 have a spread of about 15 ° centered on the maximum intensity angles θ1 and θ2. For this reason, when the maximum intensity angles θ1 and θ2 of the light L1 and the light L2 are separated by 15 ° or more, light of each wavelength is easily visually recognized separately.

  Further, since the maximum intensity angles θ1 and θ2 are in the condition of 0 ° to 90 °, it is necessary to satisfy [| θ1−θ2 | ≦ 75 °]. When the maximum intensity angles θ1 and θ2 of the light L1 and the light L2 are separated by 75 ° or more, light having a maximum intensity angle close to 90 ° becomes difficult to be emitted from the organic EL element, and the light emission efficiency of the organic EL element decreases. For this reason, the difference between the maximum intensity angle θ1 and the maximum intensity angle θ2 is preferably 75 ° or less in consideration of the spread of light centered on the maximum intensity angles θ1 and θ2.

  More specifically, by satisfying the relationship of [20 ° ≦ | θ1−θ2 | ≦ 40 °] or [50 ° ≦ | θ1−θ2 | ≦ 70 °], the front surface of the light emitting surface of the organic EL element is obtained. When the angle from the direction is 0 ° to 90 °, the light L1 and the light L2 are easily visually recognized separately.

  Further, when the organic EL element has the third light emitting unit together with the first light emitting unit and the second light emitting unit, the angle (maximum intensity) at which the light emission intensity of the light (L3) emitted from the third light emitting unit is maximized. The angle: θ3) is set to [15 ° ≦ | θ1-θ3 | ≦ 75 ° and 15 ° ≦ | θ2-θ3 | ≦ 75 °] with respect to the maximum intensity angles θ1 and θ2. In such a configuration, when the maximum intensity angles θ1 and θ2 satisfy [15 ° ≦ | θ1−θ2 | ≦ 75 °] as described above, the maximum intensity angles θ1, θ2, and θ3 differ by 15 ° or more, respectively. Is provided. For this reason, it becomes easy to visually recognize separately the light of light L1, L2, L3 according to the angle which the angle from the front direction of an organic EL element sees.

  When the organic EL element includes the first light emitting unit, the second light emitting unit, and the third light emitting unit, the maximum intensity angles θ1, θ2, and θ3 are [20 ° ≦ | θ1−θ2 | ≦ 40]. °] and [50 ° ≦ | θ1−θ3 | ≦ 70 °]. At this time, it is preferable that the maximum intensity angles θ2 and θ3 satisfy the relationship [20 ° ≦ | θ2−θ3 | ≦ 40 °].

As described above, when the light L1, L2, and L3 of the first light emitting unit, the second light emitting unit, and the third light emitting unit satisfy the above relationship, the maximum intensity angles θ1, θ2, and θ3 are 20 ° or more, respectively. Difference is provided. By controlling the light distribution characteristics of the organic EL element in this way, even if the light of each wavelength has a light spread centering on the maximum intensity angle θ, it is visually recognized separately according to the angle without being mixed. It becomes easy.
However, the lights L1, L2, and L3 are lights having different wavelengths, and the maximum intensity angles θ1, θ2, and θ3 are 0 ° or more and less than 90 °, respectively.

  In such an organic EL element in which the maximum intensity angle (θ1, θ2, θ3) of each light (L1, L2, L3) is prepared by the microcavity effect, the angle dependency of each light (L1, L2, L3) is determined. An example is shown in FIG. In FIG. 2, the vertical axis represents the luminance (normalized luminance) of the light (L1, L2, L3) emitted from each light emitting unit, and the horizontal axis represents the measurement angle of the luminance in the front direction of the organic EL element. In the graph shown in FIG. 2, the angles at which the luminance is the highest for the light (L1, L2, L3) emitted from each light emitting unit are known. Further, in the graph shown in FIG. 2, the change in the relative intensity of the luminance of each light can be seen according to the measurement angle.

  As shown in FIG. 2, the light (L1) has the highest luminance at the angle θ1 because the normalized luminance at the angle θ1 is high. Similarly, the light (L2) has the highest luminance at the angle θ2 because the normalized luminance at the angle θ2 is high, and the light (L3) is the highest at the angle θ3 because the normalized luminance at the angle θ3 is high. Has brightness. Here, since the angle θ1, the angle θ2, and the angle θ3 are different values, the lights (L1, L2, and L3) have different angles having the highest luminance.

  That is, at the angle θ1 at which the luminance of the light (L1) at the angle θ1 is highest, the luminance of the light (L2) and the light (L3) is not highest. Therefore, the light (L1) is easily recognized at the angle θ1. Similarly, light (L2) and light (L3) are easily recognized at angle θ2 and angle θ3.

[Design method]
Hereinafter, a method for controlling the light distribution characteristics of the organic EL element using the above-described microcavity effect will be described. In the following example, a method for designing an organic EL element in which the color tone changes depending on the viewing angle by controlling the maximum intensity angles θ1, θ2, and θ3 to predetermined angles will be described.

  A specific structure of the organic EL element for explaining the design method is shown in FIG. The organic EL element shown in FIG. 2 includes a transparent electrode 11, a first light emitting unit 12, a first intermediate electrode 13, a second light emitting unit 14, a second intermediate electrode 15, a third light emitting unit 16, and a reflective electrode 17 laminated. It has the structure made. That is, the organic EL element has a configuration in which three layers of light emitting units are stacked via the intermediate electrodes 13 and 15. In FIG. 2, only the configuration related to the design method of the organic EL element is shown, and the configuration of the substrate and the like is omitted.

  In the organic EL element shown in FIG. 2, the first light emitting unit 12 arranged closest to the transparent electrode 11 emits light (L1) having the shortest wavelength. Further, the second light emitting unit 14 emits light (L2) having the longest wavelength next to L1, and the third light emitting unit 16 emits light (L3) having the longest wavelength. In addition, the light emitting points in the respective light emitting units 12, 14, and 16 are h1, h2, and h3.

  In order to set the maximum intensity angles θ1, θ2, and θ3 of the light beams L1, L2, and L3 having different wavelengths emitted from the light emitting units 12, 14, and 16 to a predetermined angle, a predetermined angle is obtained by the microcavity effect. The organic EL element is designed under the condition that the phase is strengthened in FIG. The conditions under which the phase is strengthened at this predetermined angle will be described using the configuration shown in FIGS.

  3 and 4 show a configuration in which the transparent electrode 21, the light emitting unit 22, and the reflective electrode 27 are provided on the transparent substrate 20. In general, the microcavity effect depends on the wavelength λ of emitted light, the refractive index n of each layer, and the optical path length. In the organic EL device, the wavelength λ and the refractive index n of the emitted light are low in design freedom, and it is difficult to adjust the maximum intensity angles θ1, θ2, and θ3 due to the microcavity effect. On the other hand, since the optical path length can be adjusted by adjusting the thickness of the light emitting unit of the organic EL element, the degree of freedom in design is high. That is, in the organic EL element, the maximum intensity angles θ1, θ2, and θ3 due to the microcavity effect are preferably adjusted by adjusting the optical path length. Therefore, in the following description, the design of an organic EL element that can adjust the maximum intensity angles θ1, θ2, and θ3 by adjusting the optical path length of the organic EL element will be described.

  As shown in FIGS. 3 and 4, the light from the light emitting point h has a phase change due to reflection at the reflection electrode 27, a phase change due to propagation at the light emitting unit 22, and a phase change due to reflection at the transparent electrode 21. to be influenced. Further, the phase change due to the propagation of light emitted from the light emitting point h of the light emitting unit 22 in the light emitting unit 22 is the distance d from the light emitting point h to the reflective electrode 27 and the distance from the transparent electrode 21 to the reflective electrode 27. L is affected.

As shown in FIG. 3, when the phase change due to reflection at the reflective electrode 27 is φ _m and the phase change due to propagation of the distance d is represented by the following equation (1), the distance d at which the phase of light from the light emitting point h intensifies is Is represented by the following formula (2).

In addition, as shown in FIG. 4, in consideration of the phase change due to reflection at the transparent electrode 21, the phase change φ _e due to reflection at the transparent electrode 21 and the phase change due to propagation of the distance L are expressed by the following equation (3): The distance L by which the phases of light are strengthened is expressed by the following formula (4).

Note that λ is the wavelength in vacuum, θ _EML is the angle of light inside the light emitting unit, n _EML is the refractive index of the light emitting unit, and θ is the angle of light in the air, which are related to Snell's law. In addition, the phase change φ _m due to reflection at the interface between the light emitting unit 22 and the reflective electrode 27 and the phase change φ _e due to reflection at the interface between the light emitting unit 22 and the transparent electrode 21 are functions of θ _{EML that} changes depending on the angle. It has become. M and l are repeating units in which the phase of light strengthens.

  Here, the distance d at which the light of a specific wavelength λ is strengthened at a specific angle θ is given by the following formula (5) derived from the above formula (2).

  Further, the distance L at which the light of the specific wavelength λ is strengthened at the specific angle θ is given by the following formula (6) derived from the formula (4).

  Accordingly, by determining the values of the refractive index n, the light emission wavelength λ, and the required maximum intensity angle θ of the light emitting unit 22, the light emitting point h to the reflective electrode 27 can be obtained from the above equations (5) and (6). And the distance L from the transparent electrode 21 to the reflective electrode 27 can be obtained. These formulas (5) and (6) can also be applied to an organic EL element having a configuration in which light emitting units are stacked.

  For example, in the organic EL element shown in FIG. 2, the distance d1 from the light emitting point h1 of the first light emitting unit 12 to the reflective electrode 17, the distance d2 from the light emitting point h2 of the second light emitting unit 14 to the reflective electrode 17, and A distance d3 from the light emitting point h3 of the third light emitting unit 16 to the reflective electrode 17 can be obtained by the above formula (5).

  More specifically, the distance d1 from the light emitting point h1 of the first light emitting unit 12 to the reflective electrode 17 is the refractive index n1 of the first light emitting unit 12, the wavelength λ1 of the light L1 emitted from the first light emitting unit 12, and The value of the maximum intensity angle θ1 of the light L1 emitted from the target first light emitting unit 12 can be determined from the above equation (5). As the distance d1 to be obtained, a value for each repeating unit m corresponding to the period in which the phases strengthen is obtained from the equation (5).

  Similarly, the distance d2 from the light emitting point h2 of the second light emitting unit 14 to the reflective electrode 17 and the distance d3 from the light emitting point h3 of the third light emitting unit 16 to the reflective electrode 17 are also the same for the respective light emitting units 14 and 16. By determining the refractive indexes n2 and n3, the wavelengths λ2 and λ3 of the lights L2 and L3, and the maximum intensity angles θ2 and θ3 of the target lights L2 and L3, they can be obtained from the above equation (5). Also in the distances d2 and d3, values are obtained from the equation (5) for each repeating unit m corresponding to the period in which the phases are strengthened.

  Note that light emitted from each light emitting unit also passes through other light emitting units. For this reason, the phase change due to the propagation of light in the light emitting unit is affected by not only the refractive index of the light emitting unit that emitted the light but also the refractive index of other light emitting units. However, the light emitting unit is usually formed mainly of an organic layer material, and has a refractive index of about 1.6 to 1.8 and a small difference in refractive index. For this reason, the influence on the distances d1, d2, d3 and the distance L due to the refractive index of the other light emitting units is small and can be ignored. Similarly, since the film thickness of the intermediate electrode is small, the influence due to the difference in the refractive index of the intermediate electrode has little influence on the distances d1, d2, d3 and the distance L and can be ignored.

  In the organic EL element shown in FIG. 2, the distance L from the transparent electrode 11 to the reflective electrode 17 is determined from the parameters (n, λ, θ) of the lights L1, L2, and L3, respectively, from the above equation (6). Another value is obtained for each repeating unit l. In this case, the distance L from the transparent electrode 11 to the reflective electrode 17 is preferably matched to the light whose light intensity is to be increased most. In general, the distance L from the transparent electrode 11 to the reflective electrode 17 is preferably determined in accordance with the light having the shortest wavelength (L1), which is the light having the lowest luminous efficiency. By adopting a condition that increases the intensity of light having the lowest light emission efficiency, it becomes easy to improve the light emission efficiency of the organic EL element.

  The distance L from the transparent electrode 11 to the reflective electrode 17 and the distances d1, d2, and d3 from the light emitting points h1, h2, and h3 to the reflective electrode 17 have the relationship [d3 <d2 <d1 <L]. It holds. For this reason, arbitrary repeating units m and l satisfying the above relationship are selected from the distances L, d1, d2 and d3 obtained for the respective repeating units m and l. Further, the smaller distances L, d1, d2, and d3 are advantageous in terms of productivity and cost. Therefore, it is preferable to select a value of the distance L that intensifies the light L1 having the shortest wavelength and to select the distances d1, d2, and d3 that satisfy the above relationship. The repeating units m and l in the distances L, d1, d2, and d3 do not need to select the same number of periods, and the most appropriate number of periods can be selected for each of the distances L, d1, d2, and d3. .

[Specific examples of design]
An example of a design method using the above formulas (5) and (6) for the organic EL element having the configuration shown in FIG. In the following description, [15 ° ≦ | θ1−θ2 | ≦ 75 °], [15 ° ≦ | θ1−θ3 | ≦ 75 °], and [15 ° ≦ | θ2−θ3 | ≦ 75 °] are satisfied. Therefore, a design for controlling the light distribution characteristics of the organic EL element so that θ1 = 0 °, θ2 = 30 °, and θ3 = 60 ° will be described.

In the first light emitting unit 12, the wavelength λ1 of the emitted light L1 is 460 nm, and the refractive index n1 of the first light emitting unit 12 is 1.74. In this configuration, when the maximum intensity angle θ1 of the emitted light L1 is set to 0 °, the distances L and d1 at which the phase strengthens at the air angle of 0 ° are calculated from the equations (5) and (6). At this time, from the formula of Fresnel reflectivity, by setting θ _EML1 = 0 °, Φm = −0.83π, and Φe = −0.63π, the distances L and d1 from the formulas (5) and (6) are as follows: Can be asking. As described below, for the distances L and d1, the length (thickness) at which the light intensity in the 0 ° direction of the light L1 is maximized is obtained as a value for each repeating unit m and l.

  d1 = 55 nm (m1 = 0), 121 nm (m1 = 1), 187 nm (m1 = 2), 253 nm (m1 = 3), 319 nm (m1 = 4), 385 nm (m1 = 5), 451 nm (m1 = 6) , 518 nm (m1 = 7)

  L = 96 nm (l1 = 0), 163 nm (l1 = 1), 229 nm (l1 = 2), 295 nm (l1 = 3), 361 nm (l1 = 4), 427 nm (l1 = 5), 493 nm (l1 = 6) , 559 nm (l1 = 7)

Similarly, in the second light emitting unit 14, the wavelength λ2 of the emitted light L2 is 530 nm, and the refractive index n2 of the second light emitting unit 14 is 1.74. In this configuration, when the maximum intensity angle θ2 of the emitted light L2 is set to 30 °, _θEML2 = 16.7 °, and the distances L and d2 at which the phases are strengthened from the equations (5) and (6) are as follows. It is required as follows.

  d2 = 66 nm (m2 = 0), 225 nm (m2 = 1), 384 nm (m2 = 2), 543 nm (m2 = 3), 702 nm (m2 = 4), 861 nm (m2 = 5), 1020 nm (m2 = 6) , 1179 nm (m2 = 7) ...

  L = 116 nm (l2 = 0), 275 nm (l2 = 1), 434 nm (l2 = 2), 593 nm (l2 = 3), 752 nm (l2 = 4), 911 nm (l2 = 5), 1070 nm (l2 = 6) , 1229 nm (l2 = 7)

Further, in the third light emitting unit 16, the wavelength λ3 of the emitted light L3 is 620 nm, and the refractive index n3 of the third light emitting unit 16 is 1.74. In this configuration, when the maximum intensity angle θ3 of the emitted light L3 is 60 °, _θEML3 = 29.8 °, and the distances L and d3 that enhance the phase from the equations (5) and (6) are as follows. It is required as follows.

  d3 = 85 nm (m3 = 0), 291 nm (m3 = 1), 496 nm (m3 = 2), 701 nm (m3 = 3), 907 nm (m3 = 4), 1112 nm (m3 = 5), 1317 nm (m3 = 6) , 1522nm (m3 = 7) ...

  L = 150 nm (l3 = 0), 355 nm (l3 = 1), 561 nm (l3 = 2), 766 nm (l3 = 3), 971 nm (l3 = 4), 1177 nm (l3 = 5), 1382 nm (l3 = 6) , 1587 nm (l3 = 7) ...

  By selecting a value satisfying the relationship [d3 <d2 <d1 <L] from the distances L, d1, d2, and d3 obtained for each of the repeating units m and l as described above, [15 ° ≦ | θ1 −θ2 | ≦ 75 °], [15 ° ≦ | θ1−θ3 | ≦ 75 °], and [15 ° ≦ | θ2−θ3 | ≦ 75 °] are designed. be able to. In the above example, by using L = 559 nm (l1 = 7), d1 = 385 nm (m1 = 5), d2 = 225 nm (m2 = 1), d3 = 85 nm (m3 = 0), the maximum intensity angle θ1 , Θ2, θ3, and [d3 <d2 <d1 <L], and an organic EL element having a small total thickness can be manufactured. The distance L was selected from the value of the longest wavelength light (L1) that generally has the lowest luminous efficiency.

  By selecting the distances L, d1, d2, and d3 in the design of the organic EL element, a sufficiently large difference can be provided in the maximum intensity angles θ1, θ2, and θ3. For this reason, in the front direction of the organic EL element, light having different wavelengths according to the angles is strengthened for each of the maximum intensity angles θ1, θ2, and θ3, and an organic EL element in which different colors are visually recognized according to the viewing angle is configured. be able to. That is, by determining the maximum intensity angles θ1, θ2, and θ3 and obtaining the distances L, d1, d2, and d3, the light distribution characteristics of each light emitting unit of the organic EL element in which different colors are visually recognized according to the viewing angle. Can be controlled.

  The configuration of the organic EL element, the refractive index n, the emission wavelength λ, and the maximum intensity angle θ of each light emitting unit are arbitrary values and can be variously changed. In general, when the number of light emitting units is n and the maximum intensity angle when each light emitting unit emits light alone from the light emission viewing side is θ1, θ2, θ3,. It is preferable that θ1 ≦ θ2 ≦ θ3 ≦. In an actual organic EL element, the maximum intensity angle θ of each light emitting unit can be determined by examining the angle dependency of the intensity of light emitted from each light emitting unit in the formed element or panel.

  In the production of the organic EL element, the adjustment of the distances d1, d2, d3 and the distance L is preferably adjusted by the thickness of the hole transport layer or the electron transport layer of each light emitting unit. Alternatively, the thickness is preferably adjusted with a material having high electron or hole mobility. By using these layers for the adjustment of the distances d1, d2, d3 and the distance L, the increase in the voltage of the organic EL element is small, and the disadvantages due to the increase in thickness can be minimized.

In addition, the distance d in designing the actual organic EL element is preferably within a range of ± 5 nm, and preferably within a range of ± 3 nm, from the numerical value obtained by the above equation (5). Further, the distance L in designing the actual organic EL element is obtained by the above formula (6), and is preferably within a range of ± 15 nm from the selected numerical value, and is preferably within a range of ± 10 nm. preferable. In the above design example, d is calculated on the assumption that the light emission position is the interface between the hole transport side and the light emitting layer. However, depending on the carrier balance of the element, the film thickness of the light emitting layer is about (20 to 20). This is because a difference within a range of 30 nm) is assumed.
In an actual organic EL element, if the numerical values of the distances d and L are formed within the above range, the effect as the above-described organic EL element can be exhibited.

<2. Embodiment of Organic Electroluminescence Device>
Hereinafter, embodiments of the present invention will be described in detail in the order of an organic EL element, a method for manufacturing the organic EL element, and a light emitting device.

[Organic EL device]
FIG. 5 is a cross-sectional configuration diagram showing an outline of the organic EL element 1 of the embodiment.
The organic EL element 1 shown in FIG. 5 is provided on one main surface of a transparent substrate (unknown), and in order from the transparent substrate side, the transparent electrode 2, the first light emitting unit 4, the intermediate electrode 6, and the second light emission. The unit 8 and the reflective electrode 10 are laminated. In the organic EL element 1, the first light-emitting unit 4 and the second light-emitting unit 8 are configured using materials having individual optical characteristics. For this reason, each of the first light emitting unit 4 and the second light emitting unit 8 emits light having different wavelengths. Further, the organic EL element 1 takes out the first emitted light obtained in the light emitting region of the first light emitting unit 4 and the second emitted light obtained in the light emitting region of the second light emitting unit 8 from the transparent substrate side. It is configured as a bottom emission type.

  In the organic EL element 1, a power source 5 is connected to the transparent electrode 2 and the intermediate electrode 6 from the outside, and a power source 7 is connected to the intermediate electrode 6 and the reflective electrode 10 from the outside. The transparent electrode 2, the intermediate electrode 6, and the reflective electrode 10 can be independently controlled by the control unit 9 via the power supplies 5 and 7.

[Transparent substrate]
The transparent substrate has optical transparency with respect to the first emitted light generated by the first light emitting unit 4 and the second emitted light generated by the second light emitting unit 8 in the visible light. Examples of the transparent substrate material constituting the transparent substrate include glass, quartz, and a resin substrate. A particularly preferable transparent substrate is a resin substrate that can give flexibility to the organic EL element 1. The resin substrate may be configured to have a gas barrier layer as necessary.

  As the resin material constituting the resin substrate, a conventionally known resin material is used. For example, acrylic resin such as acrylic acid ester, methacrylic acid ester, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate, polyvinyl chloride ( PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), nylon (Ny), aromatic polyamide, polyether ether ketone, polysulfone, polyether sulfonate, polyimide, polyether imide, polyolefin, epoxy resin, etc. Examples of the resin film include cycloolefin resins and cellulose ester resins. In addition, a heat-resistant transparent film (product name Sila-DEC, manufactured by Chisso Corporation) having silsesquioxane having an organic-inorganic hybrid structure as a basic skeleton, and a resin film formed by laminating two or more layers of resin materials, etc. be able to.

[Transparent electrode]
The transparent electrode 2 is in a state of being electrically connected to the intermediate electrode 6 via the power source 5. The transparent electrode 2 is provided as an anode or a cathode for the first light emitting unit 4. When the intermediate electrode 6 is a cathode, it is used as an anode, and when the intermediate electrode 6 is an anode, it is used as a cathode. In addition, the transparent electrode 2 has light transmittance with respect to the first emitted light generated by the first light emitting unit 4 and the second emitted light generated by the second light emitting unit 8 in the visible light.

The transparent electrode 2 is composed of a conductive material that is suitable as an anode or a cathode and using the above-described conductive material having excellent light transmittance. Examples of the conductive material suitably used for the configuration of the transparent electrode 2 include transparent conductive materials such as oxide semiconductors such as ITO, ZnO, TiO ₂ and SnO ₂ .

  Moreover, the transparent electrode 2 may be comprised with the metal thin film which has a metal as a main component. A metal thin film is a metal film having a thickness in the range of 8 to 30 nm. The metal contained in the metal thin film is not particularly limited as long as it is a highly conductive metal, and examples thereof include silver, copper, gold, platinum group, titanium, and chromium. The transparent electrode 2 may contain only one kind of these metals or two or more kinds.

  From the viewpoint of high conductivity, the transparent electrode 2 is preferably composed of silver as a main component, and is composed of silver or an alloy containing silver as a main component. Examples of the alloy mainly composed of silver (Ag) constituting the transparent electrode 2 include silver magnesium (AgMg), silver copper (AgCu), silver palladium (AgPd), silver palladium copper (AgPdCu), and silver indium (AgIn). ) And the like.

  Moreover, when the transparent electrode 2 is comprised as a metal thin film, it is preferable that the transparent electrode 2 is provided on the base layer. The foundation layer is a layer provided on the transparent substrate side of the transparent electrode 2. The material constituting the underlayer is not particularly limited. For example, it preferably has an action of suppressing aggregation of silver when forming the transparent electrode 2 made of silver or an alloy containing silver as a main component. As an example, a nitrogen-containing compound or a sulfur-containing compound may be mentioned.

  The transparent electrode 2 has a sheet resistance of 30Ω / sq. Or less, preferably 10 Ω / sq. The following is more preferable. The transparent electrode 2 preferably has a light transmittance at a wavelength of 550 nm of 30% or more, and preferably 50% or more.

[Light emitting unit]
The light emitting unit includes a light emitting layer configured using an organic material. The 1st light emission unit 4 is provided in the transparent electrode 2 side among several light emission units. This 1st light emission unit 4 is a laminated body containing the light emitting layer comprised at least with the organic material. Further, the laminated structure of the first light emitting unit 4 is not limited, and may be any one of general laminated structures as shown in the following (i) to (vi), and further according to necessity. It may have a layer. In addition, the detail of each layer which comprises a light emission unit is mentioned later.

(I) (anode) / hole injection transport layer / light emitting layer / electron injection transport layer / (cathode)
(Ii) (anode) / hole injection transport layer / light emitting layer / hole blocking layer / electron injection transport layer / (cathode)
(Iii) (anode) / hole injection / transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron injection / transport layer / (cathode)
(Iv) (anode) / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / (cathode)
(V) (anode) / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / (cathode)
(Vi) (anode) / hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / (cathode)

  The 2nd light emission unit 8 is arrange | positioned rather than the 1st light emission unit 4 at the reflective electrode 10 side among the some light emission units which have the light emitting layer comprised using the organic material. The second light emitting unit 8 is a laminate including at least a light emitting layer made of an organic material, like the first light emitting unit 4. Further, the laminated structure of the second light emitting unit 8 is not limited, and may be any of the common laminated structures as shown in the examples (i) to (vi) above, and further according to necessity. It may have a layer. Further, the second light emitting unit 8 may have a stacked structure different from that of the first light emitting unit 4, and the stacking order of the above (i) to (vi) may be reversed.

[Intermediate electrode]
The intermediate electrode 6 is provided as an anode or a cathode for the first light emitting unit 4. When the transparent electrode 2 is an anode, it is used as a cathode, and when the transparent electrode 2 is a cathode, it is used as an anode. The intermediate electrode 6 is also used as an anode or a cathode for the second light emitting unit 8, and is used as a cathode when the reflective electrode 10 is an anode, and is used as an anode when the reflective electrode is a cathode. Further, the intermediate electrode 6 is electrically connected to the transparent electrode 2 via the power source 5 and electrically connected to the reflective electrode 10 via the power source 7.

  The intermediate electrode 6 is configured using a conductive material excellent in light transmittance among materials suitable for the transparent electrode 2 described above. The intermediate electrode 6 preferably has the same sheet resistance and light transmittance as the transparent electrode 2.

[Reflective electrode]
The reflective electrode 10 is provided as an anode or a cathode for the second light emitting unit 8, and is used as an anode when the intermediate electrode 6 is a cathode, and is used as a cathode when the intermediate electrode 6 is an anode. The reflective electrode 10 is in a state of being electrically connected to the intermediate electrode 6 via the power source 7.

  The reflective electrode 10 has good reflection characteristics with respect to the first emitted light generated by the first light emitting unit 4 and the second emitted light generated by the second light emitting unit 8 among visible light. Preferably it is. Such a reflective electrode 10 is comprised using the metal material excellent in the reflective characteristic from the electroconductive material suitable as a cathode or an anode. For example, the reflective electrode 10 is made of gold, platinum, silver, copper, aluminum, or the like.

[Power supply]
One of the power sources 5 is connected to the transparent electrode 2 and the intermediate electrode 6. The power source 5 has a positive electrode connected to the anode side of the transparent electrode 2 and the intermediate electrode 6 with respect to the first light emitting unit 4 and a negative electrode connected to the cathode side. The other power source 7 is connected to the intermediate electrode 6 and the reflective electrode 10. The power source 7 has a positive pole connected to the anode side of the intermediate electrode 6 and the reflective electrode 10 with respect to the second light emitting unit 8, and a negative pole connected to the cathode side.

  In the configuration of the organic EL element 1 shown in FIG. 5, the transparent electrode 2 is connected to the positive electrode of the power source 5 as the anode of the first light emitting unit 4, and the intermediate electrode 6 is the negative electrode of the power source 5 as the cathode of the first light emitting unit 4. It is connected to the. The intermediate electrode 6 is connected to the positive electrode of the power source 7 as the anode of the second light emitting unit 8, and the reflective electrode 10 is connected to the negative electrode of the power source 7 as the cathode of the second light emitting unit 8. In addition, what is necessary is just to reverse the connection with the power supplies 5 and 7 when the laminated structure of the 1st light emission unit 4 and the 2nd light emission unit 8 is reverse.

  The power supplies 5 and 7 are configured such that the voltage and current applied to the transparent electrode 2, the intermediate electrode 6, and the reflective electrode 10 are controlled by the control unit 9. The control unit 9 can be configured by a computer, for example. Thereby, the light emission ratio and light emission amount of the 1st light emission unit 4 and the 2nd light emission unit 8 can be controlled, and light control property and toning property can be improved. It is also possible to control the light emission of the first light emitting unit 4 and the second light emitting unit 8 individually. In addition, the control unit 9 performs control to make the total current supplied to the first light emitting unit and the second light emitting unit 8 constant, and control to make the current of the light emitting unit with high visibility constant. By such control, it is possible to perform effective light adjustment and color adjustment of the organic EL element.

  The organic EL element 1 only needs to have at least two power supplies, but may have a larger number of power supplies. However, in order not to complicate the apparatus, it is preferable that the number of power sources is smaller than the number of electrodes.

[Other configurations]
The organic EL element 1 preferably has a sealing material that covers from the transparent electrode 2 to the reflective electrode 10 on the transparent substrate. Furthermore, you may provide the protective member which covers this sealing material. The protective member is for mechanically protecting the organic EL element 1, and particularly when the sealing material is a sealing film, mechanical protection for the organic EL element 1 is not sufficient. It is preferable to provide a member. As the protective member, a glass plate, a polymer plate, a polymer film, a metal plate, a metal film, or a polymer material film or a metal material film is applied. Among these, it is preferable to use a polymer film because it is lightweight and thin.

  In addition, the organic EL element 1 includes a light extraction layer for efficiently extracting the first emitted light and the second emitted light generated in the first light emitting unit and the second light emitting unit 8 as necessary. You may have in a necessary part. Furthermore, the organic EL element 1 may have a conductive auxiliary electrode connected to the transparent electrode 2 and the intermediate electrode 6 at a position that does not overlap the light emitting region. The material constituting the auxiliary electrode is preferably a metal having low resistance such as gold, platinum, silver, copper, or aluminum.

[Drive of organic EL element]
The organic EL element 1 configured as described above generates a first light emission in the light emitting region of the first light emitting unit 4 by applying a voltage in a predetermined state between the transparent electrode 2 and the intermediate electrode 6. The first emitted light passes through the transparent electrode 2 and the transparent substrate, and is observed as a light emitting region on the light extraction surface side of the transparent substrate. Further, when a voltage is applied between the intermediate electrode 6 and the reflective electrode 10 in a predetermined state, second emitted light is generated in the light emitting region of the second light emitting unit 8. The second emitted light passes through the transparent electrode 2 and the transparent substrate, and is observed as a light emitting region on the light extraction surface side of the transparent substrate.

  In addition, when a voltage is applied to the transparent electrode 2, the intermediate electrode 6, and the reflective electrode 10 in a predetermined state, the light emitting region of the first light emitting unit 4 and the light emitting region of the second light emitting unit 8 are overlapped. Shape emission is observed. The organic EL element may be driven by applying an AC voltage, and the AC waveform to be applied may be arbitrary.

[Other modified configurations]
The organic EL element described above has a configuration in which two light emitting units of the first light emitting unit 4 and the second light emitting unit 8 are stacked. However, the organic EL element 1 may have a configuration in which a plurality of light emitting units are further stacked. Even in this case, the relationship between the optical characteristics of the light emitting unit on the transparent electrode side and the light emitting unit on the reflective electrode side is the relationship between the first light emitting unit 4 and the second light emitting unit 8 described above. That's fine.

[Material of each layer constituting first light emitting unit and second light emitting unit]
Details of the constituent materials of the respective layers constituting the first light emitting unit 4 and the second light emitting unit 8 are shown below. First light emitting unit 4. And the material suitable for the structure of an organic EL element is selected and used for the 2nd light emission unit 8 from the materials shown below.

[Light emitting layer]
The light-emitting layer is a layer that emits light by recombination of electrons injected from the cathode side and holes injected from the anode side, and the light-emitting portion is adjacent to the light-emitting layer even in the layer of the light-emitting layer. It may be an interface with the layer to be used. The light emitting layer preferably contains a phosphorescent compound as a light emitting material. Note that a fluorescent material may be used as the light emitting material, or a phosphorescent compound and a fluorescent material may be used in combination. The light emitting layer may be a mixture of a plurality of light emitting materials.

  As a light emitting layer, if the light emitting material contained satisfies the light emission requirement, there will be no restriction | limiting in particular in the structure. Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. In this case, it is preferable to have a non-light emitting intermediate layer (not shown) between the light emitting layers.

  The total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably in the range of 1 to 40 nm because a lower driving voltage can be obtained. The total film thickness of the light emitting layer includes the intermediate layer when a non-light emitting intermediate layer exists between the light emitting layers. However, in the case of a so-called tandem element in which a plurality of light emitting layer units are stacked via an intermediate connector, the light emitting layer here is the sum of the light emitting layers in each light emitting unit not including the intermediate connector portion.

  In the case of a light emitting layer having a structure in which a plurality of layers are laminated, the thickness of each light emitting layer is preferably adjusted within a range of 1 to 50 nm, and more preferably adjusted within a range of 1 to 20 nm. preferable. When the plurality of stacked light emitting layers correspond to blue, green, and red light emitting colors, there is no particular limitation on the relationship between the film thicknesses of the blue, green, and red light emitting layers.

  The light emitting layer as described above is formed by forming a known light emitting material or host compound by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. Can do.

  As a structure of the light-emitting layer, it is preferable that a light-emitting material contains a host compound (also referred to as a light-emitting host) and a light-emitting material (also referred to as a light-emitting dopant). Applicable light emitting dopants include, for example, International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication No. 2011/134013. International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. As described in JP 2011/073149, JP 2012-069737, JP 2009-114086, JP 2003-81988, JP 2002-302671, JP 2002-363552, and the like. List compounds Door can be.

  Examples of the host compound include JP-A Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, and 2002-334786. Gazette, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645 2002-338579, 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227 2002-231453, 2003-3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002-302516, 2002-305083, 2002-305084, 2002-308837, US 2003/0175553, US 2006 No. 0280965, U.S. Patent Publication No. 2005/0112407, U.S. Patent Publication No. 2009/0017330, U.S. Patent Publication No. 2009/0030202, U.S. Patent Publication No. 2005/238919, International Publication No. 2001/039234, International Publication No. 2009/021126, International Publication No. 2008/056746, International Publication No. 2004/093207, International Publication No. 2005/089025, International Publication No. 2007/063796, International Publication No. 2007/063754, International Publication No. 2004/107822, International Publication No. 2005/030900, International Publication No. 2006/114966, International Publication No. 2009/086028, International Publication No. 2009/003898, International Publication No. 2012 No. 023947, JP 2008-074939 A, JP 2007-254297 A, EP 2034538, and the like.

[Hole injection layer / electron injection layer]
The injection layer is a layer provided between the electrode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and its industrialization front line (issued by NTS, November 30, 1998) The details are described in the second chapter, Chapter 2, “Electrode Materials” (pages 123 to 166). In the organic EL element, the injection layer includes a hole injection layer and an electron injection layer.

  An injection | pouring layer is a structure layer which can be provided as needed. In the case of a hole injection layer, it is disposed between the anode and the light emitting layer or the hole transport layer, and in the case of an electron injection layer, it is disposed between the cathode and the light emitting layer or the electron transport layer.

  The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. Specific examples include a phthalocyanine layer represented by copper phthalocyanine, an oxidation Examples thereof include an oxide layer typified by vanadium, an amorphous carbon layer, and a polymer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. Moreover, the material described in Japanese translations of PCT publication No. 2003-519432 can also be used.

  The details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, a metal layer typified by strontium or aluminum, Examples thereof include an alkali metal halide layer typified by potassium fluoride, an alkaline earth metal compound layer typified by magnesium fluoride, and an oxide layer typified by molybdenum oxide. The electron injection layer is preferably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 1 nm to 10 μm.

[Hole transport layer]
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers. The hole transport material has characteristics of hole injection or transport and electron barrier properties.

  The hole transport material may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. Furthermore, porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, particularly aromatic tertiary amine compounds can be used.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include, for example, N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N '-Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1 , 1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di -P-tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-dipheni -N, N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis ( N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and further in US Pat. No. 5,061,569 Two fused aromatic rings described in the molecule, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPD), 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] tril, in which three triphenylamine units described in Kaihei 4-308688 are linked in a starburst type And phenylamine (abbreviation: MTDATA).

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material. JP-A-11-251067, J. Org. Huang et. al. , Applied Physics Letters, 80 (2002), p. A so-called p-type hole transport material as described in 139 can also be used. These materials are preferably used because a light emitting element with higher efficiency can be obtained.

  The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  In addition, impurities can be doped into the material of the hole transport layer to increase transportability. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. , 95, 5773 (2004), etc. can be applied.

[Electron transport layer]
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer (not shown) are also included in the electron transport layer. The electron transport layer can be provided as a single-layer structure or a multi-layer structure.

  In the electron transport layer having a single layer structure and the electron transport layer having a multilayer structure, an electron transport material (also serving as a hole blocking material) constituting a layer portion adjacent to the light emitting layer emits electrons injected from the cathode. It only needs to have a function of transmitting to the layer. As such a material, any one of conventionally known compounds can be selected and used. Examples include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane, anthrone derivatives, and oxadiazole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as a material for the electron transport layer. it can. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (abbreviation: Alq3), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) ) Aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (abbreviation: Znq), and the central metals of these metal complexes A metal complex replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as a material for the electron transport layer.

  In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with alkyl groups or sulfonic acid groups can be preferably used as the material for the electron transport layer. Further, distyrylpyrazine derivatives exemplified as the material of the light emitting layer can also be used as the material of the electron transport layer, and n-type-Si, n-type-SiC, etc. as well as the hole injection layer and the hole transport layer. These inorganic semiconductors can also be used as a material for the electron transport layer.

  The electron transport layer can be formed by thinning the above material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an inkjet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  In addition, the electron transport layer can be doped with impurities to increase transportability. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like. Furthermore, it is preferable that potassium, a potassium compound, etc. are contained in an electron carrying layer. As the potassium compound, for example, potassium fluoride can be used. Thus, when the n property of the electron transport layer is increased, an element with lower power consumption can be manufactured.

  Further, as the material for the electron transport layer (electron transport compound), the same material as that for the above-described base layer may be used. This is the same for the electron transport layer that also serves as the electron injection layer, and the same material as that for the above-described underlayer may be used.

[Electron blocking layer / hole blocking layer]
The electron blocking layer / hole blocking layer is disclosed in, for example, JP-A Nos. 11-204258 and 11-204359, and “Organic EL device and its forefront of industrialization (November 30, 1998, NTS Corporation). Issue) ”on page 237, etc., there is a hole blocking layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and recombines electrons and holes by blocking holes while transporting electrons. Probability can be improved. Moreover, the structure of an electron carrying layer can be used as a hole-blocking layer as needed. The hole blocking layer is preferably provided adjacent to the light emitting layer.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense. The electron blocking layer is made of a material that has a function of transporting holes but has a very small ability to transport electrons, and improves the probability of recombination of electrons and holes by blocking electrons while transporting holes. be able to. Moreover, the structure of a positive hole transport layer can be used as an electron blocking layer as needed. The thickness of the hole blocking layer is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.

[Method of manufacturing organic EL element]
(Lamination process)
On the transparent substrate, the transparent electrode 2, the first light emitting unit 4, the intermediate electrode 6, the second light emitting unit 8, and the reflective electrode 10 are formed in this order. In addition, before the transparent electrode 2 and the intermediate electrode 6 are formed, a base layer is formed as necessary.

  In film formation of these members, film formation methods suitable for the members may be applied. Examples of film formation methods include vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, plasma CVD, and laser. Examples thereof include a CVD method, a thermal CVD method, and a coating method.

  When forming each member, each member can be patterned into a predetermined shape by performing film formation using a mask as necessary. Each member may be patterned into a predetermined shape after each layer is formed. In addition, before and after the film formation of the transparent electrode and the intermediate electrode 6, an auxiliary electrode pattern may be formed as necessary. The laminating step is preferably performed by a procedure of forming a film from the transparent electrode 2 to the reflective electrode 10 consistently by a single vacuum.

(Sealing process)
Next, although not shown here, sealing from the reflective electrode side is performed. Here, the transparent electrode 2, the intermediate electrode 6, and the terminal portion of the reflective electrode 10 are exposed, and the sealing material is covered so as to cover the laminate from the transparent electrode 2 to the reflective electrode 10 between the transparent substrate and the transparent substrate. And, if necessary, a protective member via a sealing material is bonded.

[Light emitting device]
The organic EL element of the embodiment obtained as described above can be used as a planar light emitting device. The light emitting device can increase the light emitting surface area by using a plurality of organic EL elements. In this case, the light emitting surface is enlarged by arranging (that is, tiling) a plurality of organic EL elements on the support substrate. The support substrate may also serve as a sealing material, and the organic EL element is tiled in a state where the laminate of the transparent electrode to the reflective electrode is sandwiched between the support substrate and the transparent substrate of the organic EL element. An adhesive may be filled between the support substrate and the transparent substrate, thereby sealing the transparent electrode to the reflective electrode of the organic EL element. Note that the terminals of the transparent electrode, the intermediate electrode, and the reflective electrode are exposed around the support substrate.

  In the light-emitting device having such a configuration, a large-area light-emitting region obtained by connecting light-emitting regions formed in a plurality of organic EL elements can be displayed in a pattern. In such a configuration, a non-light emitting region is generated at the joint of each organic EL element. For this reason, you may provide the light extraction member for increasing the amount of light extraction especially in the non-light-emission area | region used as the connection of a light emission area | region between organic EL elements. As the light extraction member, a light collecting sheet or a light diffusion sheet can be used.

  EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

<Production of organic EL element>
Organic EL elements of Samples 101 to 106 having an element area of 1 cm × 1 cm were produced by the following method. The organic EL element of each sample is a reflective electrode from the light emitting point of the first light emitting unit according to the design method of the above-described embodiment so that the maximum intensity angle (θ1, θ2, θ3) of each light emitting unit becomes a design value. Distance d1, the distance d2 from the light emitting point of the second light emitting unit to the reflective electrode, the distance d3 from the light emitting point of the third light emitting unit to the reflective electrode, and the distance L from the transparent electrode to the reflective electrode. It was. And the thickness of each layer of the light emitting unit of an organic EL element was prepared so that it might become the design value (distance) of this distance d1, d2, d3 and the distance L.

  Table 1 below shows the maximum intensity angles (θ1, θ2, θ3) that are the design values of the organic EL elements of the samples, and the design values (distances) of the distances d1, d2, d3, and the distance L. In Table 1, B is a light emitting unit that emits light with a wavelength of 460 nm, R is a light emitting unit that emits light with a wavelength of 620 nm, G is a light emitting unit that emits light with a wavelength of 520 nm, and Y is The light emitting unit emits light having a wavelength of 80 nm.

[Production of Organic EL Element of Sample 101]
(1) Formation of transparent electrode First, a glass substrate having a thickness of 0.7 mm was prepared as a transparent substrate. This transparent substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. Then, Ag (silver) was mask-deposited with a thickness of 15 nm on this transparent substrate to form a transparent electrode serving as an anode.

(2) Formation of 1st light emission unit Next, the transparent substrate in which the transparent electrode was formed was fixed to the substrate holder of a commercial vacuum evaporation system. Then, the materials for the respective layers constituting the first light emitting unit were filled in the respective crucibles for vapor deposition in the vacuum vapor deposition apparatus with the optimum amounts for device fabrication. As each evaporation crucible, an evaporation crucible made of a resistance heating material made of molybdenum or tungsten was used.

(2.1) Formation of hole injection layer After depressurizing to a vacuum degree of 1 × 10 ⁻⁴ Pa, an evaporation crucible containing the following compound (HAT-CN: hexaazatriphenylenehexacarbonitrile) was energized and heated. The film was deposited on the transparent electrode at a deposition rate of 0.1 nm / second to form a hole injection layer having a layer thickness of 5 nm.

(2.2) Formation of Hole Transport Layer Next, the following compound 1-A (glass transition point (Tg) = 140 ° C.) was deposited to a layer thickness of 17 nm to form a hole transport layer.

(2.3) Formation of Electron Blocking Layer Next, the following compound 1-B was deposited to a layer thickness of 10 nm to form an electron blocking layer.

(2.4) Formation of Light-Emitting Layer Next, the following compound 2-A (Tg = 189 ° C.) is deposited as a host compound so that 98 vol% and the following compound 2-B as a blue fluorescent light-emitting dopant is 2 vol%. A fluorescent light emitting layer having a layer thickness of 30 nm and exhibiting blue (B) was formed.

(2.5) Formation of Electron Transport Layer Next, the following compound 3 was deposited on the light emitting layer so that 86 vol% and LiF were 14 vol%, thereby forming a layer having a thickness of 20 nm. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the layer of layer thickness 10nm was formed. As a result, an electron transport layer that also serves as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the first light emitting unit having a stacked structure from the hole injection layer to the electron transport layer is formed. Formed.

(3) Formation of 1st intermediate electrode Next, Ag was formed into a film with a thickness of 10 nm on the 1st light emission unit, and the 1st intermediate electrode was formed.

(4) Formation of second light-emitting unit The second light-emitting unit was formed by setting the film thickness for each in the same procedure using the same material as the first light-emitting unit except for the light-emitting layer.

(4.1) Formation of hole injection layer HAT-CN was deposited to a thickness of 5 nm to form a hole injection layer.

(4.2) Formation of Hole Transport Layer Next, Compound 1-A was vapor deposited to a layer thickness of 21 nm to form a hole transport layer.

(4.3) Formation of electron blocking layer Next, the compound 1-B was vapor-deposited so as to have a layer thickness of 10 nm to form an electron blocking layer.

(4.4) Formation of Light-Emitting Layer Next, the following compound 4-A (Tg = 143 ° C.) is 85 vol% as a host compound, and compound (Ir (ppy) 3) is 15 vol% as a green phosphorescent dopant. A phosphorescent light emitting layer having a layer thickness of 20 nm and exhibiting green light emission (G) was formed.

(4.5) Formation of Electron Transporting Layer Next, the following compound 3 was deposited on the light emitting layer so that 86 vol% and LiF were 14 vol%, thereby forming a layer having a thickness of 20 nm. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the layer of layer thickness 10nm was formed. As a result, an electron transport layer that also serves as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the second light emitting unit having a stacked structure from the hole injection layer to the electron transport layer is formed. Formed.

(5) Formation of 2nd intermediate electrode Next, Ag was formed into a film with a thickness of 10 nm on the 2nd light emission unit, and the 2nd intermediate electrode was formed.

(6) Formation of third light-emitting unit The third light-emitting unit was formed by setting the film thickness for each in the same procedure using the same material as the first light-emitting unit except for the light-emitting layer.

(6.1) Formation of hole injection layer HAT-CN was deposited to a layer thickness of 5 nm to form a hole injection layer.

(6.2) Formation of hole transport layer Next, Compound 1-A was deposited to a layer thickness of 64 nm to form a hole transport layer.

(6.3) Formation of Electron Blocking Layer Next, Compound 1-B was deposited to a layer thickness of 10 nm to form an electron blocking layer.

(6.4) Formation of Light-Emitting Layer Next, Compound 2-A (Tg = 143 ° C.) is 77 vol% as a host compound, Compound 2-B is 15 vol% as an assist dopant, and Ir (pq) 2 as a red phosphorescent dopant. Was vapor-deposited so that it might become 8 vol%, and the 3rd phosphorescence light emitting layer with a layer thickness of 20 nm which exhibits red (R) was formed.

(6.5) Formation of Electron Transporting Layer Next, the following compound 3 was deposited on the light emitting layer so that 86 vol% and LiF were 14 vol%, thereby forming a layer having a layer thickness of 34 nm. Furthermore, it vapor-deposited so that the compound 3 might be 98 vol% and Li might be 2 vol%, and the layer with a layer thickness of 30 nm was formed. As a result, an electron transport layer that also serves as an electron injection layer composed of two layers of the compound 3 and LiF and the compound 3 and Li is formed, and the third light emitting unit having a stacked structure from the hole injection layer to the electron transport layer is formed. Formed.

(7) Formation of reflective electrode Next, 150 nm of aluminum was vapor-deposited to form a reflective electrode serving as a cathode.

(8) Sealing and connection of power supply Next, the laminated body of the transparent electrode to the reflective electrode is covered with a glass case from the reflective electrode side, and an epoxy-based photocurable adhesive (Luxe manufactured by Toagosei Co., Ltd.) A sealant from track LC0629B) was provided. The glass case and the transparent substrate were brought into close contact with each other through this sealant. Then, the laminated body from a transparent electrode to a reflective electrode was sealed by irradiating UV light from the glass case side and curing the sealing agent. The sealing operation with the glass case was performed in a glove box (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more) in a nitrogen atmosphere without bringing the laminate from the transparent electrode to the reflective electrode into contact with the atmosphere. . Note that the terminals of the transparent electrode, the first intermediate electrode, the second intermediate electrode, and the reflective electrode were pulled out from the glass case, and a power source was connected to these electrodes.
Thus, an organic EL element of Sample 101 was produced.

[Production of Organic EL Elements of Samples 102 to 107]
Organic EL elements of Samples 102 to 107 were produced in the same manner as Sample 101 described above except that the configuration of the light emitting unit of the organic EL element was changed as shown in Table 1. In addition, the distances d1, d2, d3 and the distance L in the organic EL elements of the samples 102 to 107 are adjusted to the thickness of the designed value by adjusting the thickness of the hole transport layer of each light emitting unit. did. In addition, Sample 105 and Sample 107 do not produce the third light emitting unit, but produce only the produced first light emitting unit and the second light emitting unit (yellow light emission, 15 vol% yellow phosphorescent light emitting dopant compound 4-B). This is the configuration.

  Table 1 shows the configuration of the light emitting units of the organic EL elements of Samples 101 to 107 and the design value of the maximum intensity angle.

<Evaluation>
[Maximum intensity angle]
About the produced organic EL element, the 1st light emission unit, the 2nd light emission unit, and the 3rd light emission unit were light-emitted separately on the conditions from which current density will be 5 mA / cm < ² > at room temperature (25 degreeC). And the light distribution characteristic (luminance) of the air mode was measured by changing the sample angle from −80 ° to 0 ° to 80 ° at intervals of 5 ° using a light radiance meter CS-2000. The maximum intensity angle obtained from the light distribution characteristics of each light emitting unit is shown in Table 2 below.

[Color shift (angle)]
The produced organic EL element was continuously driven at a room temperature (25 ° C.) under a current density of 5 mA / cm ² , from the front (0 °) and obliquely (30 ° and 60 °). A chromaticity difference ΔExy (angle change) was determined. The chromaticity difference ΔExy is a chromaticity coordinate [x0 °, y0 °] at the front (0 °) and a chromaticity coordinate [x30 °, y30 at an angle (30 °) under the condition that the peak luminance is 300 cd / m ^2. °] and chromaticity coordinates [x60 °, y60 °] obliquely (60 °), a chromaticity difference ΔExy was calculated by the following equation.
ΔExy (0-30) = [(x0 ° −x30 °) ² + (y0 ° −y30 °) ² ] ^1/2
ΔExy (0-60) = [(x0 ° −x30 °) ² + (y0 ° −y30 °) ² ] ^1/2

  Table 2 shows the measurement results of the organic EL elements of Samples 101 to 107.

  As shown in Table 2, by adjusting the thickness of each layer constituting the light emitting unit, the measurement value similar to the design value was obtained at the maximum intensity angle of the organic EL element of each sample. Therefore, the distance d1 from the light emitting point of the first light emitting unit to the reflective electrode, the distance d2 from the light emitting point of the second light emitting unit to the reflective electrode, and the light emission of the third light emitting unit based on the method described in the above embodiment. The light emitted from each light emitting unit is adjusted by adjusting the thickness of each layer of the light emitting unit of the organic EL element so that the distance d3 from the point to the reflective electrode and the distance L from the transparent electrode to the reflective electrode. The maximum intensity angle can be adjusted to a predetermined angle.

  In Sample 101 and Sample 102, the maximum intensity angle θ of each light emitting unit is [15 ° ≦ | θ1−θ3 | ≦ 75 °], [15 ° ≦ | θ1−θ2 | ≦ 75 °], and [15 ° ≦ | θ2−θ3 | ≦ 75 °] is satisfied. Furthermore, the relationship of [20 ° ≦ | θ1−θ2 | ≦ 40 °], [50 ° ≦ | θ1−θ3 | ≦ 70 °], and [20 ° ≦ | θ2−θ3 | ≦ 40 °] is satisfied. For this reason, both ΔExy (0-30) and ΔExy (0-60) are sufficiently large, and different color tones can be confirmed according to the angle at which the organic EL element is viewed. Specifically, the sample 101 exhibits blue emission near 0 °, the emission color changes from blue to green from 0 ° to around 30 °, green emission around 30 °, and from around 30 ° to 60 °. The emission color changes from green to red until around °, and red emission is emitted around 60 degrees. The sample 102 emits blue light near 0 °, changes its emission color from blue to red from 0 ° to 30 °, emits red light near 30 °, and from 30 ° to near 60 °. Changes its emission color from red to green and emits green light around 60 degrees.

  Thus, the maximum intensity angle θ of each light emitting unit is [20 ° ≦ | θ1-θ2 | ≦ 40 °], [50 ° ≦ | θ1-θ3 | ≦ 70 °], and [20 ° ≦ | θ2 By satisfying the relationship of −θ3 | ≦ 40 °], the light emitted by the three-layer light emitting units is strongly emitted at each angle, and an organic EL element whose color changes according to the viewing angle can be configured. . In this way, by controlling the maximum intensity angle θ and the thickness of each light emitting unit, it is possible to control the light distribution characteristics of the organic EL element whose color tone changes depending on the viewing angle.

  In the sample 103, the maximum intensity angle θ between the first light emitting unit and the second light emitting unit satisfies the relationship [15 ° ≦ | θ1−θ2 | ≦ 75 °]. For this reason, ΔExy (0-30) is large, and different colors are confirmed at 0 ° and 30 °.

  However, the third light emitting unit satisfies the relationship [15 ° ≦ | θ1−θ3 | ≦ 75 ° and 15 ° ≦ | θ2−θ3 | ≦ 75 °] with the first light emitting unit and the second light emitting unit. Not. For this reason, ΔExy (0-60) is small. In this case, the color difference between 0 ° and 60 ° is small, and the same color is confirmed. However, in Sample 103, since ΔExy (0-30) is large, separate colors are confirmed at 30 ° and 60 °.

  Therefore, the organic EL element of the sample 103 has characteristics such that the color tone changes greatly from 0 ° to 30 °, and further, the color tone changes from 30 ° to 60 ° to the original color (0 ° color). Specifically, magenta light emission is exhibited near 0 °, the light emission color changes from magenta to white and green from 0 ° to around 30 °, green light emission occurs around 30 °, and 60 ° from around 30 °. The emission color changes from green to white and the same magenta as the original color (0 °) until near, and the same magenta emission as 0 ° is exhibited around 60 degrees.

  In the sample 104, the maximum intensity angle θ of the second light emitting unit and the third light emitting unit is [15 ° ≦ | θ1−θ2 | ≦ 75 °] and [15 ° ≦ | θ1 with respect to the first light emitting unit. −θ3 | ≦ 75 °] is satisfied. On the other hand, the second light emitting unit and the third light emitting unit do not satisfy the relationship [15 ° ≦ | θ2−θ3 | ≦ 75 °]. Therefore, although ΔExy (0-30) and ΔExy (0-60) are large, the difference between ΔExy (0-30) and ΔExy (0-60) is small. In this case, although different colors are confirmed between 0 ° and 30 ° and 0 ° and 60 °, there is no significant change in color tone between 30 ° and 60 °.

  As described above, when the organic EL element has three or more light emitting units, at least one set of light emitting units satisfies [15 ° ≦ | θ1−θ2 | ≦ 75 °] (sample 103 and sample 104). By designing in this manner, it is possible to control the light distribution characteristics of the organic EL element whose color tone changes according to the viewing angle. In particular, like the sample 101 and the sample 102, [20 ° ≦ | θ1−θ2 | ≦ 40 °], [50 ° ≦ | θ1−θ3 | ≦ 70 °], and [20 ° ≦ | θ2−θ3 | By satisfying ≦ 40 °, an organic EL element having a large change in color tone can be configured.

  The sample 105 includes only the first light emitting unit and the second light emitting unit, and satisfies [15 ° ≦ | θ1−θ2 | ≦ 75 °] and [20 ° ≦ | θ1−θ2 | ≦ 40 °]. For this reason, ΔExy (0-30) and ΔExy (0-60) are large. For this reason, different colors are confirmed at 0 ° and 30 °, and at 0 ° and 60 °. Specifically, blue light emission is exhibited from 0 ° to around 20 °, light emission color changes from blue to white and yellow from 20 ° to 40 °, and yellow light emission is exhibited from around 40 °.

  As described above, even in a two-layer organic EL element having a light-emitting unit, by designing to satisfy [15 ° ≦ | θ1−θ2 | ≦ 75 °], the organic EL element whose color tone changes according to the viewing angle can be obtained. The light distribution characteristic can be controlled. In particular, by satisfying [20 ° ≦ | θ1−θ2 | ≦ 40 °] or [50 ° ≦ | θ1−θ2 | ≦ 70 °], an organic EL element having a greater change in color tone is formed. Can do.

  In the sample 106, the first light emitting unit, the second light emitting unit, and the third light emitting unit are all [15 ° ≦ | θ1−θ2 | ≦ 75 °], [15 ° ≦ | θ1−θ3 | ≦ 75 °]. And the relationship of [15 ° ≦ | θ2−θ3 | ≦ 75 °] is not satisfied. Similarly, in the sample 107, the first light emitting unit and the second light emitting unit do not satisfy the relationship [15 ° ≦ | θ1−θ2 | ≦ 75 °]. For this reason, in Sample 106 and Sample 107, ΔExy (0-30) and ΔExy (0-60) are small, and change in color tone is poor depending on the angle at which the organic EL element is viewed. Therefore, if at least one set of light emitting units does not satisfy [15 ° ≦ | θ1−θ2 | ≦ 75 °], it is difficult to configure an organic EL element whose color changes depending on the viewing angle.

  The present invention is not limited to the configuration described in the above-described embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

  DESCRIPTION OF SYMBOLS 1 Organic EL element, 2,11,21 Transparent electrode, 4,12 1st light emission unit, 5,7 Power supply, 6 Intermediate electrode, 8,14 2nd light emission unit, 9 Control part 10, 17, 27 Reflection electrode, 13 First intermediate electrode, 15 Second intermediate electrode, 16 Third light emitting unit, 20 Transparent substrate, 22 Light emitting unit

Claims (6)

An organic electroluminescence device comprising a light emitting unit having two or more layers and three or more electrodes sandwiching the light emitting unit,
A first light emitting unit, and a second light emitting unit that emits light having a wavelength different from that of the first light emitting unit,
The angle θ1 at which the light emission intensity of the first light emitting unit is maximized and the angle θ2 at which the light emission intensity of the second light emitting unit is maximized measured from the front direction are [15 ° ≦ | θ1−θ2 | ≦ 75 °. (However, 0 ° ≦ θ1, θ2 <90 °)] is satisfied.   The organic electroluminescence device according to claim 1, satisfying a relationship of [20 ° ≦ | θ1−θ2 | ≦ 40 °] or [50 ° ≦ | θ1−θ2 | ≦ 70 °]. The first light emitting unit, and a third light emitting unit that emits light having a wavelength different from that of the second light emitting unit,
The angle θ1 at which the light emission intensity of the first light emitting unit is maximized, the angle θ2 at which the light emission intensity of the second light emitting unit is maximized, and the light emission intensity of the third light emitting unit are maximized. The angle θ3 satisfies the following [15 ° ≦ | θ1-θ2 | ≦ 75 ° and 15 ° ≦ | θ2-θ3 | ≦ 75 ° (where 0 ° ≦ θ3 <90 °)]. Organic electroluminescence element.   The organic electroluminescence device according to claim 3, satisfying a relationship of [20 ° ≦ | θ1−θ2 | ≦ 40 °] and [50 ° ≦ | θ1−θ3 | ≦ 70 °].   The organic electroluminescence device according to claim 4, satisfying a relationship of [20 ° ≦ | θ2−θ3 | ≦ 40 °].   A light emitting device comprising the organic electroluminescence element according to claim 1.

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