JP2012252933A - Light emitting device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in light extraction efficiency and color purity to increase the color purity without a color filter having thicker film thickness by obtaining peak wavelength suitable for light emitting dopant for each color in a top emission type light emitting device having resonance structure and using a white light emitting element of a tandem structure.SOLUTION: In a red light emitting element U1 and a blue light emitting element U2, optical distances between reflective layers 11, 12 and counter electrodes 30 are respectively set to be equal for one another, and the reflective layer 11 of the red light emitting element U1 is formed of a material different from that for forming the reflective layer 12 of the light emitting device of the other color.

Description

  The present invention relates to a light emitting device using various light emitting elements and an electronic apparatus including the light emitting device.

  In recent years, a top emission type light-emitting device in which an organic EL (electroluminescence) element is formed as a light-emitting element on a substrate and light emitted from the light-emitting element is extracted on the side opposite to the substrate has been widely used as a display device for electronic devices. In the top emission method, a reflective layer is formed between one of the first electrodes (for example, an anode) formed on the substrate side and the substrate, with the light emitting element interposed therebetween, and the other second electrode (for example, a cathode) that sandwiches the light emitting element. This is a method of taking out light from the side, and is a method with high light utilization efficiency.

In a top emission type light emitting device, a technology is disclosed in which a white organic EL element is used to resonate light having a predetermined wavelength between the second electrode and the reflective layer, thereby increasing light extraction efficiency ( For example, Non-Patent Document 1). In this technique, the peak wavelength in the resonance structure is λ, the optical distance from the reflective layer to the second electrode is D, the phase shift in reflection at the reflective layer is φ _L , and the phase shift in reflection at the second electrode is An optical structure that satisfies the following formula is proposed, where φ _{U is} an integer m.
D = {(2πm + φ _L + φ _U ) / 4π} λ (1)

  In addition to having the above-mentioned resonance structure, a red organic EL element, a green organic EL element, and a blue organic EL element are stacked via an intermediate layer to form a white light emitting element having a tandem structure, and a full color using a color filter. A light emitting device that realizes the above has been proposed.

  Furthermore, the light-emitting device has such a tandem white light-emitting element, and the optical path lengths of the two organic EL elements are the same among the red organic EL element, the green organic EL element, and the blue organic EL element. In addition, a light emitting device with a simplified manufacturing process has been proposed (Patent Document 1).

  This light emitting device has a resonance structure in which the value of m is 2 or more in the equation (1) so that a plurality of peaks appear at the same optical distance. In the case of adopting the tandem structure, it is preferable to secure a film thickness of about 200 to 300 nm because characteristics are deteriorated when the film thickness of the light emitting element is reduced. In addition, if the optical distance is changed so that a peak appears for each color, the number of manufacturing steps increases. Therefore, in the case of adopting the tandem structure, in order to prevent the deterioration of the characteristics and simplify the manufacturing process, as described above, the resonance structure in which the value of m is 2 or more in the equation (1) is provided. It can be said that it is preferable.

JP 2006-30250 A

  However, the light emitting device described in Patent Document 1 may not always be designed to obtain a peak wavelength suitable for both the blue light emitting dopant and the red light emitting dopant. As a result, there is a problem that light extraction efficiency is lowered and color purity is lowered.

  Further, in the light emitting device described in Patent Document 1, since a plurality of peaks appear in one light emitting element, the color purity cannot be increased unless a dark color filter, that is, a thick color filter is used. was there.

  Against this backdrop, the present invention has a resonance structure in which the value of m is 2 or more in the formula (1), and each light emitting device using a tandem white light emitting element uses each color. The objective is to solve the problem of increasing the color purity without using a thick color filter by preventing a decrease in light extraction efficiency and color purity by obtaining a peak wavelength suitable for a light-emitting dopant.

  In order to solve the above problems, a light emitting device according to the present invention includes a plurality of pixels, and each of the plurality of pixels includes a reflection layer, a pixel electrode, and a light transmission semi-reflection layer. A plurality of light emitting portions formed between the reflective layer and the light transmissive semi-reflective layer, at least one charge separation layer formed between the plurality of light emitting portions, and a counter electrode, The optical distance between the reflective layer and the light transmissive semi-reflective layer is the same for at least two pixels, and the optical distance between the reflective layer and the light transmissive semi-reflective layer is the same. Among the pixels, the reflective layer of one pixel is formed of a material different from that of the reflective layer of the other pixel.

  In the present invention, since the optical distance between the reflective layer and the light transmissive semi-reflective layer is set to be the same for at least two pixels, each of the two pixels has a predetermined resonance structure. A peak wavelength is obtained for. In these pixels, since the reflective layer of one pixel is formed of a material different from that of the reflective layer of the other pixel, the light emission intensity of this one pixel changes, and the light emission of any pixel Shift to the wavelength side. As a result, a peak wavelength suitable for the light emitting portion for each color can be obtained, the light extraction efficiency and the color purity are prevented from being lowered, and the color purity is increased without using a thick color filter.

  As the light emitting device according to the present invention, the plurality of light emitting portions are formed between the first light emitting portion formed between the pixel electrode and the charge separation layer, and between the charge separation layer and the counter electrode. It is preferable that the second light emitting portion is formed. According to the present invention, since a common structure can be used for each pixel, the manufacturing process is simplified.

  As a light-emitting device according to the present invention, of the reflective layers of at least two pixels having the same optical distance between the reflective layer and the light-transmitting semi-reflective layer, the reflective layer of the pixel having a longer emission wavelength is more reflective. May be formed of a high material. According to the present invention, the emission intensity in the short wavelength region decreases, the emission intensity on the long wavelength side improves, and the emission spectrum shifts to the long wavelength side. As a result, the light extraction efficiency is improved and the color purity is increased.

As a light emitting device according to the present invention, a transparent layer is formed between the counter electrode and the reflective layer, and a plurality of pixels having the same optical distance between the reflective layer and the light transmitting semi-reflective layer , The phase shift amount of light reflected by the reflective layer is φ, the refractive index of the layer provided on the charge separation layer side and in contact with the reflective layer is n ₁ , the refractive index of the reflective layer is n ₂ , and the reflective layer When the extinction coefficient is k ₂ , φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )} (2) is satisfied, and the reflective layer and the above The reflective layers of a plurality of pixels having the same optical distance from the light transmissive semi-reflective layer are preferably formed of a material having a smaller phase shift as the light emission wavelength is longer.
According to the present invention, the emission intensity in the short wavelength region decreases, the emission intensity on the long wavelength side improves, and the emission spectrum shifts to the long wavelength side. As a result, the light extraction efficiency is improved and the color purity is increased. The “layer provided on the charge separation layer side and in contact with the reflective layer” may be a transparent layer formed between the counter electrode and the reflective layer, or a counter electrode.

  As the light emitting device according to the present invention, the plurality of pixels include a green pixel that emits green light, a blue pixel that emits blue light, and a red pixel that emits red light, and the reflection of the green pixel and the blue pixel. Preferably, the reflective layer of the red pixel and the green pixel is formed of a common metal material. According to the present invention, since the reflective layer of the green pixel and the blue pixel or the reflective layer of the red pixel and the green pixel is formed of a common metal material, the light extraction efficiency of the emission color that affects the power consumption can be improved. , Power consumption can be reduced.

  As the light emitting device according to the present invention, the plurality of pixels include a green pixel that emits green light, a blue pixel that emits blue light, and a red pixel that emits red light, and the red pixel or the reflective layer of the green pixel. Is preferably formed from Cu, Au, Ag, or a metal material containing these as a main component. According to the present invention, the light extraction efficiency on the long wavelength side can be improved and the power consumption can be reduced as compared with the case where the reflective layer in all color pixels is made of Al.

  In the light emitting device according to the present invention, it is preferable to form a color filter on the side of the counter electrode from which light is emitted. According to the present invention, the light extraction efficiency can be improved and the power consumption can be reduced while realizing a simple structure in which the counter electrode is provided with the color filter.

  An electronic apparatus according to the present invention includes the light-emitting device described above. Since the electronic device according to the present invention includes the light emitting device described above, power consumption can be reduced.

It is typical sectional drawing which shows the outline | summary of the light-emitting device which concerns on one Embodiment of this invention. The figure which shows the material used for the hole transport layer, the fluorescence B unit, the electron transport layer, LG101, the charge separation layer, the organic EL element for red, the organic EL element for green, the phosphorescent RG unit, and the hole block in FIG. It is. The optical distance between the reflective layer and the counter electrode is D, the phase shift in reflection at the reflective layer is φ _L , the phase shift in reflection at the counter electrode is φ _U , the peak wavelength of the standing wave is λ, and an integer is when m, when showing the optical structure _{D = {(2πm + φ L} + φ U) / 4π} in lambda, to the peak wavelength of each color, it indicates an integer m, the relationship between the film thickness to the opposite electrode from the reflective layer Figure It is. Both the red light emitting element and the blue light emitting element are made of Al and the counter electrode is made of both MgAg. The red light emitting element has an optical structure in the case of the integer m = 2, and emits blue light. It is a figure which shows the emission spectrum at the time of comprising so that an element may have an optical structure in the case of the said integer m = 3. It is a figure which shows the change of the phase shift with respect to each wavelength of Al, Cu, Au, and Ag. It is a figure which shows the change of the refractive index with respect to each wavelength of Al, Cu, Au, and Ag. It is a figure which shows the change of the extinction coefficient with respect to each wavelength of Al, Cu, Au, and Ag. It is a figure which shows the change of the reflectance with respect to each wavelength of Al, Cu, Au, and Ag. It is a figure which shows the change of the emission spectrum at the time of changing the reflection layer of a red light emitting element into Cu. It is a figure which shows the transmittance | permeability of the color filter used for the panel simulation of this embodiment. It is the figure which showed the material and film thickness of each layer of Example 1 and Example 2 of this invention. It is the figure which showed the material and film thickness of each layer of the comparative example 1 and the comparative example 2. FIG. It is the figure which showed the material of the color filter of Comparative Example 1, Comparative Example 2, Example 1, and Example 2, and the reflection layer of each pixel. It is the figure which showed the power consumption of the comparative example 1, the comparative example 2, Example 1, and Example 2. FIG. It is the figure which showed the NTSC area ratio of the comparative example 1, the comparative example 2, Example 1, and Example 2. FIG. It is the figure which showed the CIE chromaticity of the comparative example 1, the comparative example 2, Example 1, and Example 2. FIG. It is a perspective view which shows the structure of the mobile personal computer which employ | adopted the light-emitting device which concerns on embodiment of FIG. 1 as a display apparatus. It is a perspective view which shows the structure of the mobile telephone which employ | adopted the light-emitting device which concerns on embodiment of FIG. 1 as a display apparatus. It is a perspective view which shows the structure of the portable information terminal which employ | adopted the light-emitting device which concerns on embodiment of FIG. 1 as a display apparatus.

Hereinafter, various embodiments according to the present invention will be described with reference to the accompanying drawings. In the drawings, the ratio of dimensions of each part is appropriately changed from the actual one.
<A: Structure of light emitting device>
FIG. 1 is a schematic cross-sectional view showing an outline of a light emitting device E1 according to an embodiment of the present invention. The light-emitting device E1 has a configuration in which a plurality of red light-emitting elements U1, blue light-emitting elements U2, and green light-emitting elements U3 are arranged on the surface of the first substrate. In FIG. Are illustrated one by one. The light emitting device E1 of the present embodiment is a top emission type, and the light generated by the red light emitting element U1, the blue light emitting element U2, and the green light emitting element U3 is opposite to the first substrate 10, that is, the bottom of FIG. Proceed from top to bottom. For the first substrate 10, in addition to a light-transmitting plate material such as glass, an opaque plate material such as a ceramic or metal sheet can be employed.
In addition, although wiring for supplying power to the red light emitting element U1, the blue light emitting element U2, and the green light emitting element U3 to emit light is arranged on the first substrate 10, illustration of the wiring is omitted. Further, although a circuit for supplying power to the red light emitting element U1, the blue light emitting element U2, and the green light emitting element U3 is arranged on the first substrate, the circuit is not shown.

  The red light emitting element U1, the blue light emitting element U2, and the green light emitting element U3 are a reflective layer 11 or a reflective layer 12 formed on the first substrate, a pixel electrode 14 (anode), and a light extraction side translucent reflective layer. Counter electrode 30 (cathode), OLED layer fluorescent B unit 16 and phosphorescence RG23. Details will be described below.

  As shown in FIG. 1, a reflective layer 11 and a reflective layer 12 are formed on the first substrate. The reflective layer is formed of a material having light reflectivity. As this type of material, for example, a single metal such as Al (aluminum), Ag (silver), Au (gold), Cu (copper), or an alloy mainly composed of Au, Cu, or Ag is preferably used. The In the present embodiment, the reflective layer 11 of the red light emitting element U1 is formed of Cu, and the reflective layers 12 of the blue light emitting element U2 and the green light emitting element U3 are formed of Al. Thus, in this embodiment, the reflective layer 11 of the red light emitting element U1 is formed of a metal material different from the reflective layer 12 of the light emitting elements of other colors. Details will be described later.

A transparent layer 13 is formed on the reflective layer 11 and the reflective layer 12. The transparent layer 13 is formed of SiO ₂ or SiN. In the present embodiment, the transparent layers 13 of the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3 are formed of SiN.

  A pixel electrode (anode) 14 is formed on the transparent layer 13. In the present embodiment, the pixel electrode 14 is formed from an ITO transparent conductive film. In the present embodiment, the distance between the reflective layer 11 and the reflective layer 12 and the counter electrode 30 is adjusted by the film thickness of the pixel electrode 14. In this embodiment, the film thickness of the pixel electrode 14 in the red light emitting element U1 and the blue light emitting element U2 is the same, and the film thickness of the pixel electrode 14 in the green light emitting element U3 is the same as that of the pixel electrode 14 in the light emitting elements of other colors. It is set thinner than the film thickness. Details will be described later.

  On the pixel electrode 14, a hole transport layer (HTL: Hole transport layer; in addition, since there is another hole transport layer, the hole transport layer 15 is indicated as a hole transport layer (HTL 1) 15) 15 is formed. The As shown in FIG. 2, α-NPD ((N- (1-naphthyl) -N-phenyl) benzidine) is used for the hole transport layer (HTL1) 15.

  On the hole transport layer (HTL1) 15, the fluorescent B unit 16 is formed. The fluorescent B unit 16 is formed of an organic EL material that emits light by combining holes and electrons. In this embodiment, the organic EL material is a low molecular material, and the blue host material (B-Host) is 10,10′-di (biphenyl-2-yl) -9 as shown in FIG. 9'-bianthracene is used. As the blue dopant material (B-Dopant), 4,4′-bis [2- {4- (N, N-diphenylamino) phenyl} vinyl] biphenyl is used as shown in FIG.

A charge separation layer (CGL: Carrier Generation Layer) 20 is formed on the fluorescent B unit 16. The charge separation layer 20 has an electron transport layer (ETL: Electron Transport Layer; there are other electron transport layers, so the electron transport layer 17 is indicated as an electron transport layer (ETL1) 17) 17, LG101 (hexaazatriphenylenehexacarbon). Nitrile, see FIG. 2) 18 is formed. As shown in FIG. 2, Alq3 (tris (8-quinolinolato) aluminum) is used for the electron transport layer (ETL1) 17. A hole transport layer (HTL: Hole transport layer, in which the hole transport layer 19 is indicated as a hole transport layer (HTL2) 19) 19 is formed.
As shown in FIG. 2, Alq3 (tris (8-quinolinolato) aluminum) is used for the electron transport layer (ETL1) 17. As shown in FIG. 2, α-NPD ((N- (1-naphthyl) -N-phenyl) benzidine) is used for the hole transport layer (HTL2) 19.

On the charge separation layer 20, a phosphorescent RG unit 23 is formed. The phosphorescent RG unit 23 is formed of an organic EL material that emits light by combining holes and electrons. In the present embodiment, the organic EL material is a low molecular material, and includes a red organic EL element 21 and a green organic EL element 22. As shown in FIG. 2, the red organic EL element 21 includes a red host material (TCTA: 1,4,7-triazacyclononane-N, N ′, N ″ -triacetate) and a red dopant (Ir ( MDQ) ₂ (acac): consists of bis (2-methyl-dibenzo [f.h] quinoxaline) (acetylacetonate) iridium (III)).
As shown in FIG. 2, the green organic EL element 22 includes a green host material (TPBi: 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene) and a green dopant material ( Ir (ppy) ₃ : Tris (2-phenylpyridinate) iridium (III)).

  A hole block layer (HBL: Hole Block Layer) 24 is formed on the phosphorescent RG unit 23. For the hole blocking layer 24, TPBi (1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene) is used.

  An electron transport layer (ETL2) 25 is formed on the hole block layer 24. As shown in FIG. 2, Alq3 (tris (8-quinolinolato) aluminum) is used for the electron transport layer (ETL2) 25.

  On the electron transport layer (ETL2) 25, a counter electrode (cathode) 30 is formed as a light extraction side translucent reflective layer. In the present embodiment, the counter electrode 30 is made of MgAg (magnesium silver alloy).

A sealing layer 31 is formed on the counter electrode 30. For the sealing layer 31, a transparent resin material, for example, SiO ₂ or SiN is used. In the present embodiment, the sealing layer 31 is made of SiN. A second substrate 32 is disposed on the sealing layer 31. The second substrate 32 is formed of a light transmissive material such as glass. A color filter and a light shielding film (not shown) are formed on the surface of the second substrate 32 facing the first substrate. The light shielding film is a film body of a light shielding body in which an opening is formed to face each light emitting element U1, U2, U3. A color filter is formed in the opening. The second substrate 32 on which the color filter and the light shielding film are formed is bonded to the first substrate via the sealing layer 31.

  In the present embodiment, a red color filter that selectively transmits red light is formed in the opening corresponding to the red light emitting element U1, and the blue light is selectively transmitted in the opening corresponding to the blue light emitting element U2. A blue color filter is formed, and a green color filter that selectively transmits green light is formed in the opening corresponding to the green light emitting element U3. The above is the structure of the light-emitting device of this embodiment.

<B: Optical structure>
Next, the optical structure in the light emitting device E1 of the present embodiment will be described. In the light emitting device E1 in the present embodiment, the optical distance from the reflective layer 11 and the reflective layer 12 to the counter electrode 30 as the light extraction side translucent reflective layer is set to a predetermined value, whereby the reflective layer 12 and the counter electrode 30 are set. A resonant structure that generates a standing wave is adopted.

Specifically, the optical distance between the reflective layer 11 and the reflective layer 12 and the counter electrode 30 is D, the phase shift in reflection at the reflective layer 11 and the reflective layer 12 is φ _L , and the phase shift in reflection at the counter electrode 30 Is φ _U , the peak wavelength of the standing wave is λ, and the integer is m, the structure satisfies the following formula.
D = {(2πm + φ _L + φ _U ) / 4π} λ (3)

  In the above equation (3), assuming that the refractive index n of the layer between the reflective layer 12 of Al and the counter electrode 30 of MgAg is 1.8, the optical distance D between the reflective layer 12 and the counter electrode 30 is an integer m, FIG. 3 is a diagram in which peak wavelengths are plotted assuming red, green, and blue colors.

  As shown in the region surrounded by an ellipse in FIG. 3, the red peak wavelength when m = 2 in the above equation (3) is the same as the blue peak wavelength when m = 3 in the above equation (3). It can be seen that a peak is obtained at a distance between Al and MgAg.

  Therefore, in the light emitting device having the tandem structure as shown in FIG. 1, the red light emitting element U1 and the blue light emitting element U2 are both made of Al and the counter electrode 30 is made of both MgAg, and then red light is emitted. The element U1 has an optical structure when m = 2 in the above equation (3), and the blue light emitting element U2 has an emission spectrum when configured to have an optical structure when m = 3 in the above equation (3). Is shown in FIG. As shown in FIG. 4, in the light emitting device having the tandem structure as shown in FIG. 1, the reflective layer and the counter electrode of the red light emitting element U1 and the blue light emitting element U2 are formed of the same material, and the optical from the reflective layer to the counter electrode is formed. It can be seen that even when the target distance is set to be the same, light emission in the blue region and the red region can be extracted.

  However, in this case, when the distance from the reflective layer to the counter electrode is matched with the emission peak in the blue region, the wavelength may be closer to the shorter wavelength than the peak wavelength appropriate for the red emission dopant. As a result, light extraction efficiency may decrease and color purity may deteriorate. In addition, since the color separation of the red light emitting element and the blue light emitting element is performed only by the color filter, a color filter having high cut-off characteristics is required.

  Therefore, in the present embodiment, the material of the reflective layer 11 in the red light emitting element U1 is formed of a material different from that of the reflective layer 12 in the blue light emitting element U2. Specifically, the reflective layer 11 in the red light emitting element U1 is made of a material having a low reflectance at a wavelength in the blue region and a small phase shift amount in the red region. When such a material is used, the peak wavelength can be shifted to the long wavelength side in the red light emitting element U1.

The relationship between the phase shift and the peak wavelength is expressed by the following equation. First, when the above equation (3) is transformed,
λ = 4Dπ / (2πm + φ _L + φ _U ) (4)
It becomes. That is, it can be seen that the peak wavelength of the standing wave shifts to the longer wavelength side when the phase shift at the reflection interface is small even with the same film thickness.

The phase shift is represented by φ [rad] as the phase shift amount, n _{1 as} the refractive index of the layer between the reflective layer and the counter electrode, n _{2 as} the refractive index of the reflective film, and k ₂ as the extinction coefficient of the reflective film. It can be expressed by the following formula.
φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )} (5)
FIG. 5 shows the result of calculating the amount of phase shift with Al, Cu, Au, and Ag, which are typical metal materials, where n ₁ is 1.8 as the refractive index of the layer between the reflective layer such as a transparent layer and the counter electrode. Shown in FIG. 6 shows the change in the refractive index n with respect to each wavelength of each of the metal materials Al, Cu, Au, and Ag, and FIG. 7 shows the change in the extinction coefficient k.
As can be seen from FIG. 5, the phase shift amount is smaller when Cu, Au, or Ag is used than when Al is used as the metal material.

  FIG. 8 shows the reflectance at the interface between the medium having a refractive index of 1.8 and various metal reflective films. In order to increase the light extraction efficiency, a higher reflectance is better. As shown in FIG. 8, it can be seen that Cu, Au, and Ag have a high reflectance at a wavelength in the red region (600 nm or more).

  As described above, in the case of the light emitting element having the resonance structure as described above and having the tandem structure, in order to shift the peak wavelength to the long wavelength side in the red light emitting element U1, the reflective layer of the red light emitting element U1. As the 11 metal materials, Cu, Au, and Ag are suitable.

  As an example, FIG. 9 shows an emission spectrum when the reflective layer 11 of the red light emitting element U1 is changed to Cu. As shown in FIG. 9, it can be seen that when the reflective layer 11 of the red light emitting element U1 is changed to Cu, the emission intensity in the blue region (region of 450 to 470 nm) is lowered. It can also be seen that the emission spectrum intensity in the red region (region around 600 nm) is improved and is shifted to the longer wavelength side. Therefore, it can be seen that when the reflective layer 11 of the red light emitting element U1 is changed to Cu, the light extraction efficiency is improved and the color purity is increased for the red light emitting element U1.

  Therefore, in the present embodiment, the reflective layer 11 used for the red light emitting element U1 employs Cu, Au, or Ag having a small phase shift to reduce the emission intensity in the blue region of 450 to 470 nm. The light extraction efficiency in the red region, which is longer than 600 nm, is improved. Al was adopted for the reflective layer 12 used for the green light emitting element U3 that emits green having a wavelength of 520 to 560 nm and the blue light emitting element U2 that emits blue having a wavelength of 450 to 470 nm.

<C: Panel simulation>
Next, a panel simulation performed for confirming reduction of power consumption and expansion of color gamut when Cu having a small phase shift is used for the reflective layer 11 of the red light emitting element U1 will be described.
In this simulation, Example 1 and Example 2 having the same configuration as the light emitting device E1 shown in FIG. 1 and almost the same configuration as the light emitting device E1 shown in FIG. In addition, Comparative Example 1 and Comparative Example 2 in which Al was used as the reflective layer were compared.
Further, in this simulation, as shown in FIG. 10, two types of color filters, CF1 which is a thin color filter and CF2 which is a thick color filter, were used. As CF1, which is a thin color filter, as shown in FIG. 10, a color filter having a transmittance of 95% for light of 600 nm or more is used as the red color filter CF1-R. As the green color filter CF1-G, a color filter having a transmittance of 85 to 90% for light of 520 to 560 nm was used. As the blue color filter CF1-B, a color filter having a transmittance of 80 to 85% for light of 430 to 470 nm was used.
As the thick color filter CF2, a color filter having a transmittance of 90% for light of 600 nm or more is used as the red color filter CF2-R. As the green color filter CF2-G, a color filter having a transmittance of 65 to 70% for light of 520 to 560 nm was used. As the blue color filter CF2-B, a color filter having a transmittance of 60 to 65% for light of 430 to 470 nm was used.

<C-1: Structure of Example 1>
The light emitting device of Example 1 has the same structure as the light emitting device E1 shown in FIG. 1, and the thickness of each layer was set as shown in FIG. In particular, Cu was used for the reflective layer 11 of the red light emitting element U1, and the film thickness was 100 nm. Moreover, Al was used for the reflective layer 12 of the blue light emitting element U2 and the green light emitting element U3, and the film thickness was 100 nm. The pixel electrodes 14 of the red light emitting element U1 and the blue light emitting element U2 are made of ITO and have a film thickness of 140 nm. The pixel electrode 14 of the green light emitting element U3 is made of ITO and has a thickness of 70 nm. Thin color filters CF1-R, CF1-G, and CF1-B were used as the color filters.
<C-2: Structure of Example 2>
In the light emitting device of Example 2, the thickness of each layer is the same as that of Example 1, and the thick color filters CF2-R, CF2-G, and CF2-B are used as color filters, which is different from Example 1. ing.
<C-3: Structure of Comparative Example 1>
The light emitting device of Comparative Example 1 has almost the same structure as the light emitting device of Example 1, but differs from the light emitting device of Example 1 in that Al is used for the reflective layer of all the light emitting devices. The thickness of each layer in Comparative Example 1 was set as shown in FIG. Thin color filters CF1-R, CF1-G, and CF1-B were used as the color filters.
<C-4: Structure of Comparative Example 2>
The light emitting device of Comparative Example 2 has the same thickness as each of the light emitting devices of Comparative Example 1, and differs from Comparative Example 1 in that thick color filters CF2-R, CF2-G, and CF2-B are used as color filters. ing.
The color filter of each example and the material of each pixel are shown in FIG.

<C-5: Results of panel simulation>
As shown in FIG. 14, when the power consumption of Comparative Example 1 is normalized to 1.00, the power consumption of Comparative Example 2 is 1.62, the power consumption of Example 1 is 1, and the power consumption of Example 2 is 1. .58. As described above, the power consumption greatly depends on the color filter to be used, and it can be seen that the power consumption is reduced although the embodiment is slightly more.

  Further, as shown in FIG. 15, the color gamut (NTSC area ratio) was 92 in Comparative Example 1, 104 in Comparative Example 2, 99 in Example 1, and 108 in Example 2. Thus, regarding the color gamut, it can be seen that the color gamut of the example is wider than that of the comparative example due to the effect of the increased color purity of the red light emitting element.

  Further, FIG. 16 shows CIE chromaticity of the red light emitting element. As shown in FIG. 16, it can be seen that the example is closer to the vertex of the NTSC coordinates than the comparative example.

  As described above, in the top emission type light emitting device having the resonance structure in which the value of m is 2 or more in the formula (3) and using the tandem white light emitting element, the reflective layer of the red light emitting element is By using Cu and using Al for the reflective layers of light emitting elements of other colors, it is possible to obtain peak wavelengths suitable for light emitting dopants for each color, increase light extraction efficiency, and thick color filters The color purity could be increased without using.

<D: Application example>
Next, an electronic apparatus using the light emitting device according to the present invention will be described. FIG. 17 is a perspective view illustrating a configuration of a mobile personal computer that employs the light emitting device E1 according to the above-described embodiment as a display device. The personal computer 2000 includes a light emitting device E1 as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. Since the light emitting device E1 uses an organic EL element, it is possible to display an easy-to-see screen with a wide viewing angle.

  FIG. 18 shows a configuration of a mobile phone to which the light emitting device E1 according to the above-described embodiment is applied. The cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and a light emitting device E1 as a display device. By operating the scroll button 3002, the screen displayed on the light emitting device E1 is scrolled.

  FIG. 19 shows a configuration of a portable information terminal (PDA: Personal Digital Assistant) to which the light emitting device E1 according to the above-described embodiment is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and a light emitting device E1 as a display device. When the power switch 4002 is operated, various kinds of information such as an address book and a schedule book are displayed on the light emitting device E1.

  Electronic devices to which the light-emitting device according to the present invention is applied include those shown in FIGS. 17 to 19, digital still cameras, televisions, video cameras, car navigation devices, pagers, electronic notebooks, electronic papers, and calculators. , Word processors, workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices equipped with touch panels, and the like.

  In the above-described embodiment, the case where the integer m is 2 in the formula (3) has been described. However, the present invention is not limited to this, and the case where the integer m is 3 or more is also described. Applicable.

  Furthermore, in the above-described embodiment, an example in which Cu is used as the reflective layer of the red light emitting element has been described. However, the present invention is not limited to this, and Au or Ag is used as the reflective layer of the red light emitting element. Alternatively, an alloy having at least one of Cu, Au, and Ag as a main component may be used.

  In the above-described embodiment, the example in which the reflective layer of the green light emitting element and the blue light emitting element are formed of the same material and the reflective layer of the red light emitting element is formed of different materials has been described. The configuration is not limited. For example, the reflective layer of the red light emitting element and the green light emitting element may be formed of the same material, and the reflective layer of the blue light emitting element may be formed of different materials.

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate, 11 ... Reflective layer, 12 ... Reflective layer, 13 ... Transparent layer, 14 ... Pixel electrode, 15 ... Hole transport layer, 16 ... Fluorescence B unit, 17 ... Electron Transport layer, 18 ... LG101, 19 ... Hole transport layer, 20 ... Charge separation layer, 21 ... Red organic EL device, 22 ... Green organic EL device, 23 ... Phosphorescent RG unit, 24 ... Hole block Layer, 25 ... electron transport layer, 30 ... counter electrode, 31 ... sealing layer, 32 ... second substrate, E1 ... light emitting device, U1 ... red light emitting element, U2 ... blue light emitting element, U3 ... green light emitting element

Claims (8)

A light emitting device in which a plurality of pixels are formed,
Each of the plurality of pixels is
A reflective layer;
A pixel electrode;
A light transmissive semi-reflective layer;
A plurality of light emitting portions formed between the reflective layer and the light transmissive semi-reflective layer;
At least one charge separation layer formed between the plurality of light emitting units;
A counter electrode,
The optical distance between the reflective layer and the light transmissive semi-reflective layer is the same for at least two pixels;
Of the two pixels having the same optical distance between the reflective layer and the light transmissive semi-reflective layer, the reflective layer of one pixel is formed of a material different from the reflective layer of the other pixel. ,
A light emitting device characterized by that.   The plurality of light emitting portions include a first light emitting portion formed between the pixel electrode and the charge separation layer, and a second light emitting portion formed between the charge separation layer and the counter electrode. The light emitting device according to claim 1, comprising:   Of the reflective layers of at least two pixels having the same optical distance between the reflective layer and the light transmitting semi-reflective layer, the reflective layer of the pixel having a longer emission wavelength is formed of a material having a higher reflectance. The light-emitting device according to claim 1 or 2. A transparent layer is formed between the counter electrode and the reflective layer,
In a plurality of pixels having the same optical distance between the reflective layer and the light transmissive semi-reflective layer, the phase shift amount of light reflected by the reflective layer is φ, and the reflection is provided on the charge separation layer side. When the refractive index of the layer in contact with the layer is n ₁ , the refractive index of the reflective layer is n ₂ , and the extinction coefficient of the reflective layer is k ₂ ,
φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )}
The filling,
The reflective layers of a plurality of pixels having the same optical distance between the reflective layer and the light-transmitting semi-reflective layer are formed of a material having a smaller phase shift as the emission wavelength is longer. The light emitting device according to any one of claims 1 to 3. The plurality of pixels include a green pixel that emits green light, a blue pixel that emits blue light, and a red pixel that emits red light.
5. The reflective layer of the green pixel and the blue pixel or the reflective layer of the red pixel and the green pixel is formed of a common metal material. 6. Light-emitting device. The plurality of pixels include a green pixel that emits green light, a blue pixel that emits blue light, and a red pixel that emits red light.
6. The light emitting device according to claim 1, wherein the reflective layer of the red pixel or the green pixel is formed of Cu, Au, Ag, or a metal material containing these as a main component. apparatus.   The light-emitting device according to claim 1, wherein a color filter is formed on a side of the counter electrode from which light is emitted.   An electronic apparatus comprising the light emitting device according to claim 1.

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