JP2006244713A - Organic electro-luminescence device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electro-luminescence device of which hue change dependent on angle of the field of vision can be reduced, having a monochromatic light emitting layer formed between a first electrode and a second electrode, and a reflective layer formed on the first electrode side for reflecting light emitted from the light emitting layer to carry out outgoing of the light through the second electrode. <P>SOLUTION: In the organic electro-luminescence device, L<SB>1</SB>is optical path length from a luminescence source position 33a to the reflective layer 34, L<SB>2</SB>is optical path length from a reflective interface at a device end on a second electrode 32 side to the reflective layer 34, and λ is the central wavelength in a wavelength region of outgoing light whose taking out is desired. The optical path length L<SB>1</SB>is chosen so that the light of the wavelength λ is strengthened by interference, and the optical path length L<SB>2</SB>is chosen so that the light of the wavelength λ is weakened by the interference. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescent element. Specifically, a monochromatic light emitting layer is provided between a first electrode and a second electrode, and reflects light emitted from the light emitting layer. The present invention relates to an organic electroluminescent element in which a reflective layer for emitting light from a second electrode is provided on the first electrode side.

  An organic electroluminescent element (organic EL element) generally has a structure in which an organic layer including a light emitting layer having a thickness of about several tens to several hundreds of nanometers is sandwiched between a reflective electrode and a translucent electrode. In such an organic EL element, light emitted from the light emitting layer interferes in the element structure and is extracted outside. Conventionally, attempts have been made to increase luminous efficiency by using such interference.

  In Patent Document 1, the distance from the light emitting position to the reflective layer is determined by using the interference between the light emitted from the light emitting layer in the direction of the translucent electrode and the light emitted in the direction of the reflective electrode. It has been proposed to increase the light emission efficiency by setting so as to resonate.

  In Patent Document 2, in consideration of reflection at the interface between the translucent electrode and the substrate, both the distance from the light emitting position to the reflective electrode and the distance from the light emitting position to the interface between the translucent electrode and the substrate are specified. is doing.

  In Patent Document 3, the desired wavelength resonates with the film thickness between the translucent electrode and the reflective electrode using interference caused by multiple reflection of light between the translucent electrode and the reflective electrode. By setting so, the luminous efficiency is increased.

  All of the above conventional techniques use interference of emitted light in order to increase the light emission efficiency.

By the way, in the light radiate | emitted from the organic EL element, there existed a problem that a hue change arises with a viewing angle. In order to reduce such a change in hue due to the viewing angle, use of interference of emitted light has not been studied in the past.
JP 2002-289358 A JP 2000-243573 A International Publication WO01 / 039554 Pamphlet

  An object of the present invention is to provide an organic EL element capable of reducing a change in hue due to a viewing angle.

In the present invention, a monochromatic light emitting layer is provided between the first electrode and the second electrode, and the reflective layer for reflecting the light emitted from the light emitting layer and emitting it from the second electrode is the first electrode. An organic EL element provided on the electrode side, wherein the optical distance from the light emitting position by the light emitting layer to the reflective layer is L _1, and the optical distance from the reflective interface at the element end on the second electrode side to the reflective layer is L ₂ , where λ is the center wavelength of the wavelength range of outgoing light to be extracted, L ₁ is the optical distance that light of wavelength λ is strengthened by interference, and L ₂ is the optical distance that light of wavelength λ is weakened by interference. It is characterized by doing.

According to the present invention, the optical distance L ₁ from the light emitting position of the light emitting layer to the reflective layer is the optical distance that the light of the center wavelength λ in the wavelength range of the outgoing light to be extracted is strengthened by interference, and the second electrode side The optical distance L ₂ from the reflection interface at the element end to the reflection layer is an optical distance at which light of wavelength λ is weakened by interference. Hereinafter, light interference caused by the optical distance L _{1 is referred} to as “first interference”, and light interference caused by the optical distance L ₂ is referred to as “second interference”.

  With reference to FIG. 2, the first interference and the second interference in the present invention will be described.

  In the organic EL element shown in FIG. 2, a reflective layer 34 is formed on a substrate 37, and a first electrode 31 is provided on the reflective layer 34. An organic layer 38 including a light emitting layer is provided on the first electrode 31. In this embodiment, the light emitting layer in the organic layer 38 is formed by adding a dopant material to the host material. The light emitting position 33a in the organic layer 38 generally differs depending on the carrier transport property of the host material in the light emitting layer. In the present invention, when the host material of the light emitting layer has an electron transporting property, the interface between the light emitting layer and the hole transporting layer is set as the light emitting position 33a. In the case where the host material of the light emitting layer is hole transportable, the interface between the electron transport layer and the light emitting layer is the light emitting position 33a. When the light emitting layer is so-called bipolar having both electron transporting properties and hole transporting properties, the center position in the thickness direction of the light emitting layer is set as the light emitting position 33a.

  A second electrode 32 is provided on the organic layer 38. In this embodiment, the second electrode 32 is the uppermost layer of the device, and the second electrode 32 is an air layer.

L ₁ is the optical distance from the light emitting position 33 a to the reflective layer 34, and L ₂ is the optical distance from the upper end of the second electrode 32 to the reflective layer 34. Since the outside of the second electrode 32 is an air layer and there is a difference in refractive index between the second electrode 32 and the air layer, reflection occurs at the interface between the second electrode 32 and the air layer. Therefore, the upper end portion of the second electrode 32 becomes a reflection interface of the element end portion.

  The first interference 40 is emitted from the light emitting position 33a to the second electrode 32 side, and from the light emitting position 33a to the first electrode 31 side, reflected by the reflective layer 34, and reflected from the second electrode 32 side. This is caused by interference with the light 42 emitted from the light source.

  The second interference 50 is that the light 51 emitted from the light emitting position 33a is multiple-reflected by reflection of light at the interface 32a between the second electrode 32 and the air layer and reflection of light at the reflection layer 34. Is caused by the interference.

The first interference 40 depends on the optical distance L ₁ from the light emitting position 33 a to the reflective layer 34. The second interference 50 depends on the optical distance L ₂ from the reflection interface 32 a at the element end to the reflection layer 34.

  The light extraction efficiency from the element is affected by both the first interference 40 and the second interference 50.

  Here, in order to explain the change in hue due to the viewing angle, which is a conventional problem, the first interference and the second interference when the viewing angle is considered will be considered. FIG. 3 is a diagram showing the viewing angle θ. As shown in FIG. 3, when the viewing angle θ exists, the resonance conditions of the first interference and the second interference are expressed by the following equations (6) and (7).

2L ₁ cos θ−λφ ₁ / 2π = mλ (6)
2L ₂ cos θ−λ (φ ₁ + φ ₂ ) / 2π = mλ (7)
m: Natural number including 0 L ₁ : Optical distance from the light emitting position to the reflective layer L ₂ : Optical distance from the reflective interface at the element end to the reflective layer λ: Resonance wavelength φ ₁ : When light is reflected by the reflective layer Phase change φ ₂ : Phase change when light is reflected at the reflection interface at the end of the element As is apparent from the above formulas (6) and (7), when the viewing angle θ increases, the first interference and the second The resonance wavelength of interference shifts to the short wavelength side. The extraction efficiency is a combination of the effects of both the first interference and the second interference, and this also shifts to the short wavelength side as the viewing angle increases.

  FIG. 4 is a diagram for explaining a state in which the wavelength of light extracted from the element shifts to the short wavelength side as the viewing angle increases. As shown in FIG. 4, in the spectrum A having a small half-value width, when the viewing angle is increased and shifted to the short wavelength side, the change in hue and luminance increases. On the other hand, in the spectrum B having a large half-value width, it can be seen that changes in hue and luminance are small even when the viewing angle increases and shifts to the short wavelength side. In the present invention, a change in hue and luminance due to a change in viewing angle is reduced by making the extraction efficiency spectrum such that the half width is large and the spectrum peak is flat. The fact that the extraction efficiency with a large half-value width and a flat peak can be obtained according to the present invention will be described below.

In the present invention, L ₁ is an optical distance at which light of wavelength λ is strengthened by interference. Therefore, the first interference is interference that resonates at the wavelength λ. On the other hand, L ₂ is an optical distance at which light of wavelength λ is weakened by interference. For this reason, the second interference is non-resonant with respect to the wavelength λ, and has interference wavelengths on the short wavelength side and the long wavelength side of λ. Since the actual extraction efficiency is affected by the effects of both the first interference and the second interference, when these are combined, the extraction efficiency becomes a flat spectrum with a wide half-value width. Therefore, according to the present invention, a flat extraction efficiency spectrum having a wide half-value width such as the spectrum B shown in FIG. 4 is obtained. Therefore, as described above, changes in hue and luminance due to viewing angle can be reduced.

In the present invention, the optical distances L ₁ and L ₂ preferably satisfy the following formulas (1) to (5).

2L ₁ −λ ₁ φ ₁ / 2π = mλ ₁ (1)
2L ₂ −λ ₂ (φ ₁ + φ ₂ ) / 2π = (n + 1/2) λ ₂ (2)
λ _f −30 <λ <λ _f +80 (3)
λ−15 <λ ₁ <λ + 15 (4)
λ−15 <λ ₂ <λ + 15 (5)
(Unit of λ nm)
m and n: Natural number L ₁ : Optical distance from the light emitting position to the reflective layer L ₂ : Optical distance from the reflective interface at the element end to the reflective layer λ _f : Fluorescent peak wavelength of the light emitting layer φ ₁ : Light is the reflective layer phase change at the time of reflection phi _2: phase change phi ₁ when the light is reflected by the reflecting surface of the element end, the refractive index n _e of the first electrode, the refractive index n _m of the reflective layer, the reflective layer It is shown in the extinction coefficient by the following equation when a k _m.

^{_{φ 1 = tan -1 {2n e}} k m / (n e 2 -n m 2 -k m 2)}
However, when the _{2n e k m / (n e} 2 -n m 2 -k m 2)> 0, 0 <φ 1 <π / 2
When _{2n e k m / (n e} 2 -n m 2 -k m 2) <0, π / 2 <φ 1 <π
Φ ₂ is 0 when the refractive index of the second electrode is larger than the layer outside the element, and is π when the refractive index of the second electrode is smaller than the layer outside the element.

In the above formula (3), the lower limit value of λ is λ _f −30, the upper limit value is λ _f +80, and the upper limit value is wider. When the viewing angle is increased, the spectrum of the extraction efficiency is increased. Is considered to shift to the short wavelength side.

  In general, since the second electrode is a transparent electrode, it is formed from a thin layer of a conductive metal oxide or a metal thin film. Therefore, when the outside of the second electrode is an air layer, a resin layer, or a glass layer, the interface between the second electrode and the outer layer is a reflective interface. On the other hand, when an inorganic protective layer or the like is provided outside the second electrode, the difference in refractive index between the second electrode and the inorganic protective layer is small, so the outside of the second electrode may not be a reflective interface. In such a case, the outside of the inorganic protective layer becomes a reflective interface.

  As described above, in the present invention, when the host material of the light emitting layer is electron transporting, the light emitting position by the light emitting layer is a layer adjacent to the light emitting layer and the first electrode side of the light emitting layer (for example, In the case where the host material of the light emitting layer is hole transporting, the light emitting layer and a layer adjacent to the second electrode side of the light emitting layer (for example, an electron transport layer) Let it be an interface.

  In this invention, when a metal layer is provided between the organic layer containing a light emitting layer and a 2nd electrode, it is preferable that the thickness of a metal layer is 5 nm or less. By setting the thickness of the metal layer to 5 nm or less, it is possible to reduce the influence of light reflection by the metal layer on the first interference and the second interference.

  The light emitting layer in the present invention is a monochromatic light emitting layer. In the present invention, “single color” means a color other than white, and examples thereof include blue, green, red, orange, and the like.

  The light emitting layer in the present invention is preferably formed from a host material and a dopant material. Examples of the host material for the light emitting layer include anthracene derivatives, aluminum complexes, rubrene derivatives, and arylamine derivatives.

  As the dopant material, a singlet light emitting material or a triplet light emitting material may be used. In order to obtain high luminous efficiency, it is preferable to use a triplet light emitting material which is a phosphorescent light emitting material. Examples of singlet light-emitting materials include perylene derivatives, coumarin derivatives, anthracene derivatives, tetracene derivatives, and stilbene derivatives. Examples of triplet light emitting materials (phosphorescent light emitting materials) include iridium complexes and platinum complexes.

  In the present invention, an organic layer other than the light emitting layer may be provided. Examples of the organic layer include carrier transport layers such as a hole transport layer and an electron transport layer. Examples of the hole transporting material used for the hole transporting layer include arylamine derivatives. Examples of the electron transporting material used for the electron transporting layer include perylene derivatives, anthraquinone derivatives, anthracene derivatives, and rubrene derivatives.

  In the present invention, the second electrode is generally formed from a transparent electrode. Examples of such a transparent electrode include ITO (indium tin oxide), IZO (indium zinc oxide), and transparent conductive metal oxides such as tin oxide.

  In the present invention, like the second electrode, the first electrode may be formed of a transparent electrode such as a conductive metal oxide, or may be formed of a metal thin film or the like. When the first electrode is formed from a metal thin film, it may also serve as the reflective layer in the present invention.

  In the present invention, the reflective layer is not particularly limited as long as it can reflect light, and is generally formed from a metal thin film. Examples of the metal thin film include Ag, Al, Mo, and Cr. The thickness of the reflective layer is not particularly limited, but it is generally preferable to be in the range of 100 to 300 nm.

  The organic electroluminescent display device of the present invention supplies an organic electroluminescent element having an element structure sandwiched between an anode and a cathode and a display signal corresponding to each display pixel to the organic electroluminescent element. An active matrix driving substrate provided with the active element and a transparent sealing substrate provided opposite to the active matrix driving substrate, and the organic electroluminescent element is disposed between the active matrix driving substrate and the sealing substrate. A top emission type organic electroluminescent display device in which an electrode provided on the sealing substrate side of the cathode and the anode is a transparent electrode, wherein the organic electroluminescent element is an organic material according to the present invention. It is an electroluminescent element.

  Between the sealing substrate and the organic electroluminescent element, a color filter having the same hue as the emission color may be disposed. By disposing a color filter having the same type of hue as the emission color, a change in hue due to a viewing angle can be further reduced, and a light-emitting display element with less viewing angle dependency can be obtained.

  Since the organic electroluminescent display device of the present invention is a top emission type display device, the light emitted by the organic electroluminescent element is emitted from the sealing substrate on the side opposite to the side where the active matrix is provided. Emitted. In general, an active matrix circuit is formed by laminating a large number of layers. In the case of a bottom emission type, emitted light is attenuated by the presence of such an active matrix circuit, but the organic electroluminescent display device of the present invention. Can emit light without being affected by such an active matrix circuit. In particular, since the organic electroluminescent device of the present invention has a plurality of light emitting units, the number of films through which emitted light passes is smaller in the case of the top emission type than in the case of the bottom emission type, so that the light interference. The degree of freedom of design for controlling the attenuation of the emitted light or the attenuation of the viewing angle of the emitted light can be increased.

  According to the present invention, the spectrum of light extraction efficiency from the device can be a flat spectrum with a wide half-value width. Therefore, a change in hue and a change in luminance due to a viewing angle can be reduced, and a light-emitting display with less viewing angle dependency can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.

Example 1
An organic EL element having the element structure shown in FIG. 1 was produced. As shown in FIG. 1, a reflective layer 34 (film thickness 100 nm) made of Ag is formed on a glass substrate 37, and a first electrode 31 (film thickness 65 nm) made of ITO (indium tin oxide) is formed thereon. And a hole transport layer 35 (film thickness 120 nm) was formed thereon.

  A green light emitting layer 33 (film thickness 40 nm) was formed on the hole transport layer 35, and an electron transport layer 36 (film thickness 15 nm) was formed thereon. A second electrode 32 was formed on the electron transport layer 36. The second electrode 32 was formed from IZO (indium zinc oxide) (film thickness 140 nm). Between the 2nd electrode 32 and the electron carrying layer 36, Li layer (film thickness of 0.3 nm) and Au layer (film thickness of 1.5 nm) were formed as a metal layer. Therefore, a Li layer / Au layer / IZO layer is formed on the electron transport layer 36.

  The green light emitting layer was formed using TBADN as a host material and containing 2% by weight of C545T as a dopant material.

  TBADN is 2-tertiary-butyl-9,10-di (2-naphthyl) anthracene and has the following structure.

  C545T has the following structure.

  The hole transport layer 5 is made of NPB. NPB is N, N′-di (naphthasen-1-yl) -N, N′-diphenylbenzidine and has the following structure.

  The electron transport layer 6 is made of BCP. BCP is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline and has the following structure.

(Comparative Example 1)
An organic EL element of Comparative Example 1 was produced in the same manner as in Example 1 except that the film thickness of 140 nm of IZO was changed to 70 nm in Example 1.

[Calculation of resonance wavelengths λ ₁ and λ ₂ ]
The resonance wavelength λ ₁ due to the first interference and the resonance wavelength λ ₂ due to the second interference in Example 1 and Comparative Example 1 were calculated using equations (1) and (2). The calculation results are shown in Table 1. Since optical constants such as the refractive index n and the extinction coefficient k are wavelength-dependent, the optical constants at 520 nm shown in Table 2 are used for λ ₁ and λ ₂ of Example 1, and Comparative Example 1 is used. λ ₁ was calculated using the optical constant of 540 nm, and λ ₂ of Comparative Example 1 was calculated using the optical constant at 640 nm. Note that 520 nm, 540 nm, and 640 nm are assumed from the values of approximately λ ₁ and λ ₂ calculated separately. More accurate calculation can be performed by computer simulation.

The fluorescence peak wavelength λ _f of the light emitting layer is 500 nm.

In Comparative Example 1, the fluorescence peak wavelength λ _f of the light emitting layer is 500 nm, λ ₁ is 528 nm, and λ ₂ is 621 nm. As is clear from the above formulas (3) and (5), λ ₂ is out of the scope of the present invention, and it is clear that the organic EL element of Comparative Example 1 is outside the scope of the present invention. is there.

  FIG. 5 is a diagram illustrating a simulation result of the extraction efficiency of Comparative Example 1. As is apparent from FIG. 5, both the first interference and the second interference exhibit a large extraction efficiency in the green region, and as a result, the total extraction efficiency is also a green spectrum with a small half-value width and a maximum at around 520 nm. It has become. As described above, when the viewing angle increases, the spectrum of the extraction efficiency shifts to the short wavelength side. The emission spectra of this element at viewing angles of 0 °, 30 °, and 60 ° are shown in FIG. In Comparative Example 1, since the half-value width of the extraction efficiency spectrum is small, as shown in FIG. 6, the emission color changes greatly as the viewing angle increases.

  The actual extraction efficiency is obtained by dividing the spectrum shown in FIG. 6 by the emission spectrum inside the device. The result is shown in FIG. In addition, as a spectrum of internal light emission, the spectrum obtained from the organic EL element with the same structure other than Ag of the reflective layer was used. When there is no reflective layer, it can be considered that the effect of interference is small and is almost equal to internal light emission.

  As shown in FIG. 6, it can be seen that the actual extraction efficiency in the comparative example is almost the same as the simulation and has a small half-value width.

In Example 1, the fluorescence peak wavelength λ _f of the light emitting layer is 500 nm, λ ₁ is 531 nm, and λ ₂ is 514 nm, which are within the scope of the present invention. FIG. 7 is a diagram showing a simulation result of the extraction efficiency of this example. As can be seen from FIG. 7, in the first interference, the extraction efficiency of the green region is large, and in the second interference, the extraction efficiency of blue and red is large. The total extraction efficiency of this element is affected by these two interferences, and a high extraction efficiency can be obtained over a wide wavelength range as shown in FIG.

  FIG. 8 is a diagram showing emission spectra at viewing angles of 0 °, 30 °, and 60 ° in this element. As is apparent from FIG. 8, it can be seen that there is almost no change in the emission color due to the viewing angle. The actual extraction efficiency is obtained by dividing the spectrum at the viewing angle of 0 ° shown in FIG. 8 by the internal emission.

  FIG. 9 shows the actual extraction efficiency of the example. As can be seen from FIG. 9, in the element of the example, the extraction efficiency is almost constant in a wide wavelength range. Table 3 shows changes in chromaticity and luminance at the viewing angles of 0 °, 30 °, and 60 ° of the organic EL elements of Example 1 and Comparative Example 1 (luminance change when the luminance at the viewing angle of 0 ° is 100%. ).

  As is clear from the results shown in Table 3, it can be seen that the change in chromaticity and luminance depending on the viewing angle in the organic EL element of Example 1 is reduced compared to that in Comparative Example 1.

  FIG. 10 is a cross-sectional view showing an organic EL display device including the organic EL element of the embodiment according to the present invention. In this organic EL display device, light emission in each pixel is driven using a TFT as an active element. A diode or the like can be used as the active element. In this organic EL element, a color filter is provided. This organic EL display device is a bottom emission type display device that emits and displays light below the substrate 1 as indicated by arrows.

Referring to FIG. 10, a first insulating layer 2 is provided on a substrate 1 made of a transparent substrate such as glass. The first insulating layer 2 is made of, for example, SiO ₂ and SiN _x . A channel region 20 made of a polysilicon layer is formed on the first insulating layer 2. A drain electrode 21 and a source electrode 23 are formed on the channel region 20, and a gate electrode 22 is provided between the drain electrode 21 and the source electrode 23 via the second insulating layer 3. Yes. A fourth insulating layer 4 is provided on the gate electrode 22. The second insulating layer 3 is made of, for example, SiN _x and SiO ₂ , and the third insulating layer 4 is made of SiO ₂ and SiN _x .

A fourth insulating layer 5 is formed on the third insulating layer 4. The fourth insulating layer 5 is made of, for example, SiN _x . A color filter layer 7 is provided in the pixel region on the fourth insulating layer 5. A first planarizing film 6 is provided on the color filter layer 7. A through hole portion is formed in the first planarization film 6 above the drain electrode 21, and a hole injection electrode 8 made of ITO (indium oxide) formed on the first planarization film 6 is through. It is introduced in the hall. A hole injection layer 10 is formed on the hole injection electrode (anode) 8 in the pixel region. A second planarizing film 9 is formed in a portion other than the pixel region.

  On the hole injection layer 10, a monochromatic light emitting element layer 11 according to the present invention is provided. An electron transport layer 12 is provided on the light emitting element layer 11, and an electron injection electrode (cathode) 13 is provided on the electron transport layer 12.

  As described above, in the organic EL element of this example, the hole injection electrode (anode) 8, the hole injection layer 10, the light emitting element layer 11 having the structure according to the present invention, and the electron transport are formed on the pixel region. The layer 12 and the electron injection electrode (cathode) 13 are laminated to constitute an organic EL element.

  The light emitting element layer 11 emits light of a predetermined color. This light emission is emitted to the outside through the substrate 1. A color filter layer 7 is provided on the light emitting side. As the color filter layer 7, by providing the color filter layer 7 having the same color as the light emission color from the light emitting element layer 11, the emission color can be compensated by the color filter layer 7. Has no viewing angle dependency, the change in hue due to the viewing angle can be further reduced by providing the color filter layer 7.

  FIG. 11 is a sectional view showing an organic EL display device of an embodiment according to the present invention. The organic EL display device according to this embodiment is a top emission type organic EL display device that emits light above the substrate 1 for display as shown by arrows.

  The portions from the substrate 1 to the anode 8 are fabricated in substantially the same manner as in the embodiment shown in FIG. However, the color filter layer 7 is not provided on the fourth insulating layer 5 and is disposed above the organic EL element. Specifically, the color filter layer 7 is attached on a transparent sealing substrate 10 made of glass or the like, and an overcoat layer 15 is coated thereon, and this is applied to the anode 8 via the transparent adhesive layer 14. It is attached by sticking to. In this embodiment, the positions of the anode and the cathode are reversed from those in the embodiment shown in FIG.

  A transparent electrode is formed as the anode 8, and is formed, for example, by laminating ITO having a thickness of about 100 nm and silver having a thickness of about 20 nm. As the cathode 13, a reflective electrode is formed. For example, an aluminum, chromium, or silver thin film having a thickness of about 100 nm is formed. The overcoat layer 15 is formed with an acrylic resin or the like to a thickness of about 1 μm. The color filter layer 7 may be a pigment type or a dye type. Its thickness is about 1 μm.

  The light of a predetermined color emitted from the light emitting element layer 11 is emitted to the outside through the sealing substrate 16. The color filter layer 7 is provided on the emission side, and the change in hue due to the viewing angle can be further reduced as described above. Since the organic EL display device of this embodiment is a top emission type, the region where the thin film transistor is provided can also be used as the pixel region, and the color filter layer 7 is provided in a wider range than the embodiment shown in FIG. ing. The light emitting element layer 11 is formed of an organic EL element according to the present invention and is a light emitting element layer having high light emission efficiency. However, according to this embodiment, a wider area can be used as a pixel area, and therefore, The advantages of a high light emitting element layer can be fully utilized. Further, since the light emitting element layer having a plurality of light emitting units can be formed without considering the influence of the active matrix, the degree of freedom in design can be increased.

In the above embodiment, a glass plate is used as the sealing substrate. However, the sealing substrate is not limited to the glass plate in the present invention. For example, an oxide film such as SiO ₂ or a nitride film such as SiN _{x is used.} A film-like material can also be used as a sealing substrate. In this case, since a film-like sealing substrate can be directly formed on the element, there is no need to provide a transparent adhesive layer.

The typical sectional view showing the organic EL element of one example according to the present invention. The typical sectional view for explaining the 1st interference in the present invention, and the 2nd interference. The schematic diagram which shows viewing angle (theta). The figure which shows the change of the spectrum of extraction efficiency by a viewing angle. The figure which shows the simulation result of the taking-out efficiency of the organic EL element of the comparative example 1. The figure which shows the change of the emission spectrum by the viewing angle of the organic EL element of the comparative example 1. The figure which shows the simulation result of the taking-out efficiency of the organic EL element of Example 1. FIG. The figure which shows the change of the emission spectrum by the viewing angle of the organic EL element of Example 1. FIG. The figure which shows the actual extraction efficiency of Example 1 and Comparative Example 1. Sectional drawing which shows the bottom emission type organic electroluminescence display using the organic electroluminescent element of the Example according to this invention. Sectional drawing which shows the organic electroluminescence display of the Example according to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st insulating layer 3 ... 2nd insulating layer 4 ... 3rd insulating layer 5 ... 4th insulating layer 6 ... 1st planarization film 7 ... Color filter layer 8 ... Hole injection electrode 9 DESCRIPTION OF SYMBOLS ... 2nd planarizing film 10 ... Hole injection layer 11 ... Light emitting element layer 12 ... Electron transport layer 13 ... Electron injection electrode 14 ... Transparent adhesive layer 15 ... Overcoat layer 16 ... Sealing substrate 20 ... Channel region 21 ... Drain Electrode 22 ... Gate electrode 23 ... Source electrode 31 ... First electrode 32 ... Second electrode 33 ... Light emitting layer 33a ... Light emitting position 34 ... Reflective layer 35 ... Hole transport layer 36 ... Electron transport layer 38 ... Organic layer 40 ... First interference 50 ... second interference

Claims (6)

A monochromatic light emitting layer is provided between the first electrode and the second electrode, and a reflective layer for reflecting the light emitted from the light emitting layer and emitting it from the second electrode is the first electrode. In the organic electroluminescent device provided on the side,
The optical distance from the light emitting position by the light emitting layer to the reflective layer is L ₁ , the optical distance from the reflection interface at the element end on the second electrode side to the reflective layer is L _2, and the outgoing light to be extracted When the center wavelength of the wavelength region is λ, L ₁ is an optical distance that light of wavelength λ is strengthened by interference, and L ₂ is an optical distance that light of wavelength λ is weakened by interference. Luminescent element. The organic electroluminescent device according to claim 1, L ₁ and L ₂ and satisfies the following formulas (1) to (5).
2L ₁ −λ ₁ φ ₁ / 2π = mλ ₁ (1)
2L ₂ −λ ₂ (φ ₁ + φ ₂ ) / 2π = (n + 1/2) λ ₂ (2)
λ _f −30 <λ <λ _f +80 (3)
λ−15 <λ ₁ <λ + 15 (4)
λ−15 <λ ₂ <λ + 15 (5)
(Unit of λ nm)
m and n: Natural number L ₁ : Optical distance from the light emitting position to the reflective layer L ₂ : Optical distance from the reflective interface at the element end to the reflective layer λ _f : Fluorescent peak wavelength of the light emitting layer φ ₁ : Light is the reflective layer Phase change during reflection φ ₂ : Phase change when light is reflected at the reflection interface at the edge of the element   The organic electroluminescent element according to claim 1, wherein a metal layer having a thickness of 5 nm or less is provided between the light emitting layer and the second electrode.   The organic electroluminescent element according to any one of claims 1 to 3, wherein the outside of the reflection interface at the end of the element is an air layer, a resin layer, or a glass layer. An active matrix driving substrate provided with an organic electroluminescent element having an element structure sandwiched between an anode and a cathode, and an active element for supplying a display signal corresponding to each display pixel to the organic electroluminescent element And a transparent sealing substrate provided opposite to the active matrix driving substrate, the organic electroluminescent element is disposed between the active matrix driving substrate and the sealing substrate, the cathode and the A top emission type organic electroluminescent display device in which an electrode provided on the sealing substrate side of the anode is a transparent electrode,
The said organic electroluminescent element is an organic electroluminescent element of any one of Claims 1-4, The organic electroluminescent display apparatus characterized by the above-mentioned. 6. The organic electroluminescent display device according to claim 5, wherein a color filter is disposed between the organic electroluminescent element and the sealing substrate.

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