JP2012252829A - Manufacturing method for light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for light-emitting device, of top emission type composed of a combination of a white organic EL element and a resonance structure, capable of achieving a simple manufacturing process, cost reduction and high light extraction efficiency.SOLUTION: A circuit element thin film 11 is formed on a substrate 10. For example, by the damascene method, a reflective layer/pixel electrode 12 of a red light-emitting element U1 and, by the same process, a reflective layer/pixel electrode 13 of a green light-emitting element U2 and a blue light-emitting element U3 are formed, respectively. Further, an OLED 16 layer and a counter electrode 30 are formed. An optical path D is set to satisfy the following equation. The reflective layer/pixel electrode 12 and the reflective layer/pixel electrode 13 are formed using different types of metal materials. D={(2πm+φ+φ)/4π}λ, where D is an optical length between the pixel electrodes 12, 13 and the counter electrode 30; φis a phase shift in reflection on the pixel electrodes 12, 13; φis a phase shift in reflection on the counter electrode 30; λ is a peak wavelength of a standing wave generated between the pixel electrodes 12, 13 and the counter electrode 30; and m is an integer of two or less.

Description

  The present invention relates to a method for manufacturing a light emitting device using various light emitting elements.

  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 reflection layer to the second electrode is D, the phase shift in reflection at the first electrode is φ _L , and the phase shift in reflection at the second electrode An optical structure that satisfies the following formula has been proposed, where φ is φ _U and the integer is m.
D = {(2πm + φ _L + φ _U ) / 4π} λ (1)

  In particular, in the above formula (1), when m = 0, light of a wide wavelength can be extracted with a certain degree of efficiency while simplifying the array structure in the organic EL element. Can be realized and it is easy to make high-definition pixels.

SID2010 P-146 / S.Lee, Samsung Mobile Display Co., Ltd

However, in the light emitting device having an optical structure in which m = 0 in the formula (1), the red pixel, the green pixel, and the blue pixel are extracted in order to extract light in all the red region, the green region, and the blue region. It is necessary to perform color separation with a color filter or the like. Therefore, there has been a problem that the bandwidth of the emission spectrum on the observation side is widened and the color purity is poor. In addition, when compared in the red, green, and blue wavelength regions, there is a problem that the light extraction efficiency is low. As a result, there is a problem that the power consumption of the light emitting device is increased, which is disadvantageous as panel characteristics.
In order to improve the light extraction efficiency, it is conceivable to change the structure for each color pixel, such as changing the optical distance D for each color pixel, but the conventional manufacturing method increases the number of manufacturing steps. As a result, the manufacturing cost increases.

  Against this backdrop, the present invention can simplify the manufacturing process in a method for manufacturing a top emission type light emitting device combining a white organic EL element and a resonant structure, and can reduce the cost of light. The purpose is to solve the problem of increasing the extraction efficiency.

In order to solve the above problems, a method of manufacturing a light emitting device according to the present invention includes a step of forming a circuit element thin film on a substrate, a step of forming a reflective layer / pixel electrode on the substrate, A step of forming a light emitting layer on the pixel electrode, and a step of forming a counter electrode on the light emitting layer, wherein the optical path length between the reflective layer / pixel electrode and the counter electrode is D, and the reflective layer / pixel electrode The phase shift in reflection above is φ _L , the phase shift in reflection at the counter electrode is φ _U , and the peak wavelength of the standing wave generated between the reflection layer / pixel electrode and the counter electrode is λ 2 or less When the integer is m,
D = {(2πm + φ _L + φ _U ) / 4π} λ (2)
In the method of manufacturing the light emitting device in which the optical path length D is set so as to satisfy A step of forming a layer-cum-pixel electrode, further comprising a step of forming a vertical conductive layer so as to be in direct contact with the circuit element thin film for the other color pixels, and the reflective layer for the other color pixels. The step of forming the cum pixel electrode is a step of forming the reflective layer / pixel electrode on the upper / lower conductive layer, the step of forming the reflective layer / pixel electrode for the at least one color pixel, and the step of forming the other color The step of forming the upper and lower conductive layer for the pixel is the same step, and the step of forming the reflective layer / pixel electrode for the pixel of at least one color is applied to the pixel of the other color. Characterized in that the metal material used for forming the reflective layer and the pixel electrode is a step of forming the reflective layer and the pixel electrode by using a metal material dissimilar Te.

  In the present invention, the reflection layer / pixel electrode of at least one color among the reflection layer / pixel electrodes of the red pixel, the green pixel, and the blue pixel satisfies the formula (2). It is made of a metal material different from the metal material used for the reflective layer / pixel electrode. In addition, the step of forming the reflective layer / pixel electrode of the pixel of at least one color and the step of forming the vertical conductive layer of the pixel of the other color are the same step. Therefore, as compared with the case where the reflective layer / pixel electrodes of the pixels of all colors are formed of the same metal material, the phase shift amount is different in the reflective layer / pixel electrode of the pixels of at least one color, and the light extraction efficiency is also different. In addition, since the step of forming the reflective layer / pixel electrode of the pixel of at least one color and the step of forming the vertical conductive layer of the pixel of the other color are the same step, the manufacturing process can be simplified.

As a method for manufacturing a light emitting device according to the present invention, the step of forming the reflective layer / pixel electrode for the at least one color pixel includes a phase shift amount φ, a refractive index of the light emitting layer n ₁ , and the reflective layer / pixel. When the refractive index of the electrode is n ₂ and the extinction coefficient of the reflective layer / pixel electrode is k ₂ ,
φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )} (3)
The reflective layer / pixel electrode in a pixel having a longer wavelength than the other color pixel, and a metal having a smaller phase shift φ than the reflective layer / pixel electrode in the other color pixel. It can also be a process of forming with a material.

  In the method for manufacturing a light emitting device according to the present invention, the reflective layer / pixel electrode in the pixel having a longer wavelength than the pixel of the other color satisfies the formula (3), and the reflective layer / pixel electrode in the pixel of the other color is also used. Since it is formed of a metal material having a smaller phase shift amount φ than the pixel electrode, the light extraction efficiency on the long wavelength side can be improved and the power consumption can be reduced.

  As a method for manufacturing a light emitting device according to the present invention, the at least one color pixel may be a red pixel or a red pixel and a green pixel.

  In the method for manufacturing a light emitting device according to the present invention, the reflective layer and pixel electrode of the green pixel and the blue pixel, or the reflective layer and pixel electrode of the red pixel and the green pixel are formed of a common metal material. It is possible to improve the light extraction efficiency of the luminescent color that affects the power consumption and to reduce power consumption.

  As a method for manufacturing a light-emitting device according to the present invention, a step of forming a reflective layer / pixel electrode for at least one color pixel is formed by using Cu, Au, Ag or these as a main component for a red pixel or a red pixel and a green pixel. It is also possible to form the reflective layer / pixel electrode with a metal material. In the method for manufacturing a light emitting device 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 of all color pixels is formed of Al. .

  The method for manufacturing a light emitting device according to the present invention may further include a step of forming a diffusion prevention layer between the vertical conductive layer and the reflective layer / pixel electrode for the pixels of the other colors. According to the present invention, it is possible to prevent a decrease in reflectance due to diffusion at the interface.

  As a method for manufacturing a light emitting device according to the present invention, the diffusion prevention layer may be formed of Ti, TiN, W, Ta, Mo or an alloy containing these as a main component. According to the present invention, it is possible to prevent a decrease in reflectance due to diffusion at the interface.

  As a method for manufacturing a light emitting device according to the present invention, a color filter may be formed on the counter electrode. In the light emitting device manufacturing method according to the present invention, light extraction efficiency can be improved and power consumption can be reduced while realizing a simple structure in which a color filter is provided on the upper layer of the electrode.

It is typical sectional drawing which shows the outline | summary of the light-emitting device which concerns on one Embodiment of this invention. It is a figure which shows the material used for the positive hole transport layer, the light emitting layer, and the electron carrying layer in FIG. It is a figure which shows the result of having calculated the phase shift amount with Al, Ag, Cu, and Au. 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 typical sectional drawing which shows the outline | summary of the simulation model used for the simulation which investigates the influence of the phase shift amount in a resonance structure. It is a figure which shows the result of having calculated the light extraction efficiency of the light emitting layer using the simulation model of FIG. It is a figure which shows the relationship between the wavelength in each optical structure at the time of setting m = 0, 1, 2, and 3, and light extraction efficiency. It is a figure which shows the transmittance | permeability of the color filter used for the simulation model of FIG. It is a figure which shows the structure of the organic layer film thickness of a comparative example 1, and Example 1 thru | or Example 3, and a reflecting film. It is a figure which shows the result of the power consumption and color gamut of the comparative example 1 and Example 1 thru | or Example 3. FIG. It is a figure which shows the light intensity in each pixel of the comparative example 1 and Example 1 thru | or Example 3. FIG. It is a figure which shows the change of the reflectance with respect to each wavelength of Al, Cu, Au, and Ag. It is process drawing for demonstrating the manufacturing method of the light-emitting device of this embodiment. It is process drawing for demonstrating the manufacturing method of the light-emitting device of this embodiment. It is process drawing for demonstrating the manufacturing method of the light-emitting device of this embodiment. It is process drawing for demonstrating the manufacturing method of the light-emitting device of this embodiment. It is process drawing for demonstrating the manufacturing method of the light-emitting device of this embodiment.

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 red light emitting element U1, a green light emitting element U2, and a blue light emitting element U3 are arranged on the surface of the first substrate 10. The light emitting device E1 of the present embodiment is a top emission type, and light generated in the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3 travels toward the side opposite to the first substrate 10. 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 used. In the present embodiment, the thickness of the first substrate 10 is 0.5 mm.
The first substrate 10 is provided with wiring for supplying light to the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3 to emit light, but the wiring is not shown in FIG. Further, although circuits for supplying power to the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3 are arranged on the first substrate 10, the circuit is not shown in FIG.

The red light emitting element U1 includes a reflective layer / pixel electrode 12 (first electrode) formed on the first substrate 10 and a counter electrode 30 as a light extraction side translucent reflective layer disposed on the pixel electrode 12. (Second electrode) and the OLED layer 16 disposed between the reflective layer / pixel electrode 12 and the counter electrode 30.
The green light emitting element U2 and the blue light emitting element U3 have the same configuration as the red light emitting element U1, but as will be described later, the reflective layer and pixel electrode 13 (first electrode) of the green light emitting element U2 and the blue light emitting element U3 is provided. A metal different from the reflective layer / pixel electrode 12 (first electrode) of the red light emitting element U1 is used.
Details will be described below. As shown in FIG. 1, a reflective layer / pixel electrode 12 is formed on the first substrate 10 in the red light emitting element U1, and a reflective layer / pixel electrode 13 is formed in the green light emitting element U2 and the blue light emitting element U3. The The reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 are 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 / pixel electrode 12 of the red light emitting element U1 is made of Cu, and the reflective layer / pixel electrode 13 of the green light emitting element U2 and the blue light emitting element U3 is made of Al. In the present embodiment, the thickness of the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 is set to 80 nm.

  As shown in FIG. 1, the OLED layer 16 includes a hole injection layer (HIL) 22 formed on the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13, and a hole injection layer 22. A hole transport layer (HTL) 24 formed on the light-emitting layer, a light-emitting layer 26 (EML: Emitting Layer) formed on the hole-transport layer 24, and an electron transport layer formed on the light-emitting layer 26. 28 (ETL: Electron Transport Layer).

  In the present embodiment, the hole injection layer 22 is formed of MoOx (molybdenum oxide), and the hole transport layer 24 is formed of α-NPD as shown in FIG. In the present embodiment, the hole injection layer 22 has a thickness of 2 nm, and the hole transport layer 24 has a thickness of 25 nm. Note that the hole injection layer 22 and the hole transport layer 24 may be formed of a single layer that functions as the hole injection layer 22 and the hole transport layer 24.

The light emitting layer 26 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 emits white light. As the red host material and the red dopant material, and the green and blue host materials, those shown in FIG. 2 are used. Further, DPAVBi (4,4′-bis [2- {4- (N, N-diphenylamino) phenyl} vinyl] biphenyl)) is used as a blue dopant material. Quinacridone is used as the green dopant material. In the present embodiment, the thickness of the light emitting functional layer 26 is 50 nm.
As shown in FIG. 2, the electron transport layer 28 is made of Alq3 (tris 8-quinolinolato aluminum complex). In the present embodiment, the thickness of the electron transport layer 28 is set to 25 nm.

  The counter electrode 30 is a cathode and is formed so as to cover the light emitting layer 16. The counter electrode 30 is continuous over the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3. The counter electrode 30 functions as a transflective layer having a property of transmitting part of the light reaching the surface and reflecting the other part (that is, transflective), such as magnesium or silver. It is formed from a single metal or an alloy mainly composed of magnesium or silver. In the present embodiment, the counter electrode 30 is made of MgAg (magnesium silver alloy). The thickness of the counter electrode 30 was 10 nm.

  In the present embodiment, the second substrate 50 is disposed so as to face the plurality of red light emitting elements U1, green light emitting elements U2, and blue light emitting elements U3 formed on the first substrate 10. The second substrate 50 is formed of a light transmissive material such as glass. The thickness of the second substrate 50 was 0.5 mm. A color filter and a light shielding film (not shown) are formed on the surface of the second substrate 50 facing the first substrate 10. The light shielding film is a film body of a light shielding body in which an opening is formed to face each of the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3. A color filter is formed in the opening.

  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 green light is selectively transmitted in the opening corresponding to the green light emitting element U2. A green color filter is formed, and a blue color filter that selectively transmits blue light is formed in the opening corresponding to the blue light emitting element U3.

  In the red light emitting element U1, the green light emitting element U2, and the blue light emitting element U3 of the present embodiment, between the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 and the counter electrode 30 as the light extraction side translucent reflective layer. Thus, a resonator structure for resonating light emitted from the OLED layer 16 is formed. Thereby, the light of a specific wavelength can be taken out efficiently.

  The second substrate 50 on which the color filter and the light shielding film are formed is bonded to the first substrate 10 via the sealing layer 33. The sealing layer is formed from a transparent resin material, for example, a curable resin such as an epoxy resin. The above is the structure of the light-emitting device of this embodiment.

<B: Configuration of Reflective Layer / Pixel Electrode>
Next, the configuration of the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 in the light emitting device E1 of the present embodiment will be described. The light-emitting device E1 in the present embodiment sets the optical distance from the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 to the counter electrode 30 as the light extraction side translucent reflective layer to a predetermined value. A resonance structure that generates a standing wave from the layer / pixel electrode 12 to the counter electrode 30 is employed.

Specifically, the optical distance between the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 and the counter electrode 30 is D, and the reflection at the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 is the lower electrode. Is the structure satisfying the following equation, where φ _L is the phase shift in reflection, φ _U is the phase shift in reflection at the counter electrode 30 that is the upper electrode, λ is the peak wavelength of the standing wave, and m is the integer.
D = {(2πm + φ _L + φ _U ) / 4π} λ (4)
When this equation (4) is transformed,
λ = 4Dπ / (2πm + φ _L + φ _U ) (5)
It becomes. That is, even if the film thickness is the same, if the phase shift at the reflection interface is small, the peak wavelength of the standing wave shifts to the long wavelength side. In particular, if m = 0
λ = 4Dπ / (φ _L + φ _U ) (6)
Thus, the influence of the phase shift at the reflection interface is increased.

The phase shift is expressed by the following equation, where the phase shift amount is φ [rad], the refractive index of the light emitting layer 16 is n ₁ , the refractive index of the counter electrode 30 is n ₂ , and the extinction coefficient of the counter electrode 30 is k _2. Can be represented.
φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )} (7)
FIG. 3 shows the result of calculating the phase shift amount with Al, Cu, Au, and Ag, which are typical metal materials, where the refractive index of the OLED layer 16 is n ₁ is 1.8. FIG. 4 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. 5 shows the change in the extinction coefficient k.
As can be seen from FIG. 3, the amount of phase shift is smaller when Cu, Au, or Ag is used than when Al is used as the metal material.

  In order to investigate the influence of the phase shift amount in the resonant structure, the light extraction efficiency of the light emitting layer 26 was calculated assuming a simulation model E2 as shown in FIG. The simulation model E2 shown in FIG. 6 has substantially the same configuration as the light emitting device E1 shown in FIG. 1, but an electron injection layer 29 is provided between the electron transport layer 28 and the counter electrode 30. This is different from the light emitting device E1 shown in FIG. The electron injection layer 29 is made of LiF and is formed on the electron transport layer 28 in the OLED layer 17. Further, the use of SiON (silicon oxynitride) as the sealing layer 33 is also different from the light emitting device E1 shown in FIG.

  In the simulation model E2, the thickness of the first substrate 10 is 0.5 mm, the thickness of the reflective layer / pixel electrodes 12 and 13 is 150 nm, the thickness of the hole injection layer 22 is 15 nm, and the film of the hole transport layer 24 The thickness of the light emitting layer 26 is 20 nm, the thickness of the electron transport layer 28 is 35 nm, the thickness of the electron injection layer 29 is 1 nm, the thickness of the counter electrode 30 is 10 nm, and the thickness of the sealing layer 33 is 25 nm. The thickness of 400 nm and the second substrate 50 was 0.5 mm.

In the simulation model E2 shown in FIG. 6, the results of calculating the light extraction efficiency of the light emitting layer 26 using Al, Cu, Au, Ag for the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 are shown in FIG. Show. In this calculation, the distance D between the reflective layer / pixel electrode 12 and the reflective layer / pixel electrode 13 and the counter electrode 30 as the light extraction side translucent reflective layer was 96 nm.
As is clear from FIG. 6, when Cu, Au, and Ag having a small phase shift are used for the reflective layer / pixel electrode 12, the light extraction efficiency is longer on the long wavelength side of 600 nm or more than when Al is used. It can be seen that is improved.

Therefore, in the present embodiment, the reflection layer / pixel electrode 12 used for the red light emitting element U1 adopts Cu having a small phase shift, thereby improving the extraction efficiency of red light having a long wavelength side of 600 nm or longer. Configured to do. Al was adopted for the reflective layers used for the green light emitting element U2 that emits green having a wavelength of 520 to 560 nm and the blue light emitting element U3 that emits blue having a wavelength of 450 to 470 nm. With this configuration, in the light-emitting device E1 of the present embodiment that employs an optical structure when m = 0 in the formula (4), it is possible to improve the efficiency of taking out red light and The power can be significantly reduced.
FIG. 8 shows the result of calculating the light extraction efficiency when the peak wavelength is 490 nm in each optical structure when m = 0, 1, 2, and 3. This calculation precondition is that the reflective layer / pixel electrode 13 is made of Al and has a thickness of 100 nm, the light emitting layer 26 has a thickness of 20 nm, the combined thickness of the electron transport layer 28 and the electron injection layer 29 is 40 nm, and the counter electrode 30 has The film thickness is set to 10 nm as MgAg, and the film thickness is set to 400 nm by using the sealing layer 33 as SiN, and the hole injection layer 22 and the hole transport layer 24 are combined so that the peak wavelength is 490 nm. It is adjusted. The refractive index of each layer between the reflective layer / pixel electrode 13 and the counter electrode 30 is 1.8. As shown in FIG. 8, the optical structure with m = 0 has a wider wavelength range for obtaining high light extraction efficiency than the optical structure with m = 1, 2, and 3. I understand.

<C: Panel simulation>
Next, a panel simulation performed to confirm a reduction in power consumption when Cu, Au, or Ag having a small phase shift is used for the reflective layer / pixel electrode 12 used in the red light emitting element U1 will be described. In this panel simulation, Al was used for the reflective layer and pixel electrode 13 of the green light emitting element U2 and the blue light emitting element U3.
Further, in this simulation, Comparative Example 1 was used, which has almost the same configuration as the light emitting device E1 shown in FIG.
In this simulation, as shown in FIG. 9, a color filter having a transmittance of 90% for light of 600 nm or more was used as a red color filter. As the green color filter, a color filter having a transmittance of 65 to 70% for light of 520 to 560 nm was used. As the blue color filter, a color filter having a transmittance of 60 to 65% for light of 430 to 470 nm was used.

<C-1: Structure of Comparative Example 1>
The structure of the organic layer in Comparative Example 1 is the same as that shown in FIG. 1, and the film thickness is 100 nm as shown in FIG. Further, for any of the red light emitting element, the green light emitting element, and the blue light emitting element, the reflective layer / pixel electrode is made of Al.
<C-2: Structure of Example 1>
The structure of the organic layer in Example 1 is the same as that shown in FIG. 1, and the film thickness is 100 nm as shown in FIG. Au was adopted as the reflective layer and pixel electrode 12 of the red light emitting element U1, and Al was adopted as the reflective layer and pixel electrode 13 of the green light emitting element U2 and the blue light emitting element U3.
<C-3: Structure of Example 2>
The structure of the organic layer in Example 2 is the same as the structure shown in FIG. 1, and the film thickness is 100 nm as shown in FIG. Cu was adopted as the reflective layer and pixel electrode 12 of the red light emitting element U1, and Al was adopted as the reflective layer and pixel electrode 13 of the green light emitting element U2 and the blue light emitting element U3.
<C-4: Structure of Example 3>
The structure of the organic layer in Example 3 was the same as that shown in FIG. 1, and the film thickness was 100 nm as shown in FIG. Ag was adopted as the reflective layer and pixel electrode 12 of the red light emitting element, and Al was adopted as the reflective layer and pixel electrode 13 of the green light emitting element U2 and the blue light emitting element U3.
That is, the red pixel, green pixel, and blue pixel of Comparative Example 1 and the green pixel and blue pixel of Examples 1 to 3 have the same structure.

<C-5: Results of panel simulation>
As shown in FIG. 11, when the power consumption of Comparative Example 1 is normalized to 1.00, the power consumption of Example 1 is 0.80, the power consumption of Example 2 is 0.82, and the power consumption of Example 3 It can be seen that the power consumption can be reduced by about 20% in both cases.
In addition, regarding the color gamut (NTSC coverage in the xy chromaticity diagram), compared with 75.14% of Comparative Example 1, Example 1 was 76.42%, Example 2 was 76.28%, and Example 3 Is 75.69%, indicating that the color gamut is wide.

  Further, FIG. 12 shows the light intensities of the red light emitting element, the green light emitting element, and the blue light emitting element in Comparative Example 1, Example 1, Example 2, and Example 3. As can be seen from FIG. 12, in the red light-emitting elements of Example 1, Example 2, and Example 3, the intensity of green and blue light is lower than that of Comparative Example 1. It can be seen that the intensity of light in the vicinity of 600 nm, which is the red wavelength, is stronger than other wavelengths. That is, in this embodiment, the red light extraction efficiency is improved. Further, the intensity of light in the green region (520 to 560 nm) and the blue region (450 to 470 nm) in the green pixel and the blue pixel in Example 1, Example 2, and Example 3 is different from that in Comparative Example 1. I understand that there is no.

  This can also be seen from the reflectance graph shown in FIG. FIG. 13 is a graph showing the reflectance at the interface of various metal reflective layers of Al, Ag, Cu, and Au, where the refractive index of the OLED layer 16 is 1.8. In order to increase the light extraction efficiency, it is better that the reflectance is high. However, as shown in FIG. 13, when Au and Cu are used for the reflective layer, the reflectance is high in the red region having a wavelength of 600 nm or more. It can be seen that

  In particular, since Cu has a low reflectance in a wavelength region shorter than that of a red region, it can be said that Cu is suitable for use in a reflective layer in a red pixel. Since Au has a large reduction in reflectance in a wavelength region of 550 nm or less, it is suitable to be used for a green pixel reflection layer or a red pixel reflection layer. Further, since Au has a low reflectance in the blue region, there is also an advantage that the blue light emitting component in the red pixel can be reduced and the color purity before transmission through the color filter can be improved.

  As described above, according to the present embodiment, Cu, Au, or Ag having a small phase shift is adopted as the reflective layer / pixel electrode used for the red pixel, so that m = 0 in the above equation (4). Compared with the case where Al is used as the reflective layer and pixel electrode used for the red light emitting element in the light emitting device having the optical structure, the red light extraction efficiency can be improved, and as a result, the power consumption is remarkably reduced. Can be reduced.

<D: Manufacturing process>
Next, a process for manufacturing a light-emitting device using a material of the reflective layer 12 of the red light-emitting element that is different from that of the reflective layers of the pixels of other colors will be described. As an example, an example will be described in which the reflective layer of the red light emitting element is formed of Cu, and the reflective layers of the green light emitting element and the blue light emitting element are formed of Al.

First, as shown in FIG. 14A, the circuit element thin film 11 and the interlayer insulating film 301 are formed on the first substrate 10. The interlayer insulating film 301 is formed of SiO ₂ or SiN. In any of these film formations, a known film formation method such as a PVD method, a CVD method, or a sputtering method, or a photolithography method is appropriately used. At that time, since the formation of the circuit element thin film 11 includes the manufacture of a TFT (Thin Film Transistor), a doping process or the like to the semiconductor layer is also performed. In the formation of the insulating film 301, the contact hole 360 is formed there. In order to form the film, an appropriate etching process or the like is also performed.

Next, as shown in FIG. 14B, an isolation film 302 is formed between the pixels with SiO ₂ or SiN. Note that when the insulating film 301 is formed of SiO ₂ , the isolation film 302 is formed of SiN, and when the insulating film 301 is formed of SiN, the isolation film 302 may be formed of SiO ₂ . In forming the isolation film 302, for example, a PVD method, a CVD method, a sputtering method or the like, or a photolithography method is appropriately used.

After the isolation film 302 is formed, as shown in FIG. 15A, a vertical conductive film 303 is formed by a sputtering method or a damascene method using electrolytic plating with Cu. Then, as shown in FIG. 15B, the upper and lower conductive film 303 is flattened to the position of the isolation film 302 by CMP (Chemical Mechanical Polishing) method or the like.
The vertical conductive film 303 functions as the reflective layer / pixel electrode 12 in the red light emitting element U1. As described above, in this embodiment, the reflective layer / pixel electrode 12 of the red light emitting element and the upper and lower conductive films 303 of the green light emitting element U2 and the blue light emitting element U3 are formed by the same process.

Then, as shown in FIG. 16A, Al is formed on the upper and lower conductive films 303 of the green light emitting element U2 and the blue light emitting element U3 by sputtering, and patterned by photolithography and wet etching or dry etching, The reflective film 13 is formed by removing the resist.
The reflective film 13 of the green light emitting element U2 and the reflective film 13 of the blue light emitting element U3 are formed so as to be separated on the isolation film 302 between the green light emitting element U2 and the blue light emitting element U3.

Subsequently, as shown in FIG. 16B, an isolation film 320 is formed between the pixels. The isolation film 320 is formed with its outer shape through, for example, an exposure process and a development process after application of photosensitive polyimide. Further, the cross-sectional shape of the isolation film 320 is formed into a tapered shape as shown in FIG. The isolation film 320 may be formed by performing a photolithography and etching process on SiO ₂ or SiN.

Next, as shown in FIG. 17A, an OLED layer 16 is formed by a vapor deposition method. Further, as shown in FIG. 17B, a counter electrode 30 is formed by depositing MgAg by vapor deposition.
Further, as shown in FIG. 18A, SiN is formed by a CVD method to form a sealing film 33. Further, red, green, and blue color filters 40, 41, and 42 and a light shielding film 31 are formed thereon by photolithography. Then, the second substrate 50 is bonded. The above is the manufacturing method of the light emitting device E1 of the present embodiment.

  As described above, according to the manufacturing method of the present embodiment, the reflective layer / pixel electrode 12 of the red light emitting element and the upper and lower conductive films 303 of the green light emitting element U2 and the blue light emitting element U3 can be formed by the same process. As a result, the number of manufacturing steps can be reduced as compared with the prior art.

  Further, Cu used as the reflective layer and pixel electrode 12 of the red light emitting element U1 is a material often used as a wiring material in a semiconductor manufacturing line such as an LSI or the like whose process rule is 100 nm or less. For this reason, it is possible to use techniques that have been used in semiconductor manufacturing lines, such as a technique for forming vertical conductive wiring and a planarization technique, which is advantageous in terms of the manufacturing process.

  When an Al reflective layer is formed on the Cu upper and lower conductive layers of the green light emitting element U2 and the blue light emitting element U3, patterning may be performed by dry etching, wet etching, or the like, which has a high Cu / Al selection ratio. Further, when the reflectivity of the Al surface is lowered due to alloying of the Cu / Al interface, a diffusion prevention film (Ti, TiN, W, Ta, Mo, etc.) may be formed between Cu / Al.

  In the above-described embodiment, the reflective layer / pixel electrode of the red light emitting element U1 is formed of Cu, Au, Ag or a metal material containing these as a main component, and the reflective layers of the green light emitting element U2 and the blue light emitting element U3. Although the case where the cum pixel electrode is formed of Al has been described, the present invention is not limited to this. For example, the reflective layer and pixel electrode of the red light emitting element U1 and the green light emitting element U2 are formed of Cu, Au, Ag or a metal material mainly composed of these, and the reflective layer and pixel electrode of the blue light emitting element U3 is formed of Al. You may make it do. In the above-described embodiment, the case where the integer m is 0 in the formula (4) has been described. However, the present invention is not limited to this, and the integer m is 1 or 2. Is also applicable.

  Furthermore, in the above-described embodiment, the example in which Cu, Au, and Ag are used as the reflective layer and pixel electrode of the red pixel has been described. However, the present invention is not limited to this, and the red pixel and the green pixel are used. The reflective layer and pixel electrode may be an alloy containing at least one of Cu, Au, and Ag as a main component, for example, an alloy containing Cu, Mg, and Ca, or an alloy containing Au and Cu. You may make it use.

In the embodiment described above, the material of the upper and lower conductive layers may be Au, and the plating method (or sputtering method or vapor deposition method) and the CMP method may be combined.
Further, the vertical conductive layer and the reflective layer may be made of Al (for blue light emitting element and green light emitting element), and may be formed by a combination of sputtering and CMP. In this case, Ag, Cu, and Au are formed in a later process for a red light emitting element. In addition, when using Ag, it is preferable to set it as the three-layer structure of ITO / Ag / ITO. Further, when ITO and Al are used, Ti, TiN, W, Ta, Mo, or an alloy containing these as main components may be interposed in order to prevent electrolytic corrosion of ITO and Al.

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate, 12 ... Reflection layer and pixel electrode, 13 ... Reflection layer and pixel electrode, 16 ... OLED layer, 22 ... Hole injection layer, 24 ... Hole transport layer, 26 ... Light emitting layer 28... Electron transport layer 30. Counter electrode 33. Sealing layer 50. Second substrate E 1. Light emitting device U 1 Red light emitting element U 2 Green light emitting element U 3 Blue Light emitting element

Claims (8)

Forming a circuit element thin film on a substrate;
Forming a reflective layer and pixel electrode on the substrate;
Forming a light emitting layer on the reflective layer and pixel electrode;
Forming a counter electrode on the light emitting layer, wherein D is an optical path length between the reflective layer / pixel electrode and the counter electrode, and φ _L is a phase shift in reflection on the reflective layer / pixel electrode, When the phase shift in reflection at the counter electrode is φ _U , the peak wavelength of the standing wave generated between the reflective layer / pixel electrode and the counter electrode is λ, and an integer of 2 or less is m,
D = {(2πm + φ _L + φ _U ) / 4π} λ
In the manufacturing method of the light emitting device in which the optical path length D is set to satisfy
For at least one color pixel, the step of forming the reflective layer / pixel electrode is a step of forming the reflective layer / pixel electrode so as to be in direct contact with the circuit element thin film,
For other color pixels, further comprising a step of forming a vertical conductive layer so as to be in direct contact with the circuit element thin film,
The step of forming the reflective layer and pixel electrode for the other color pixels is a step of forming a reflective layer and pixel electrode on the vertical conductive layer,
The step of forming the reflective layer and pixel electrode for the at least one color pixel and the step of forming the vertical conduction layer for the other color pixel are the same step.
The step of forming the reflection layer / pixel electrode for the pixel of at least one color uses the metal material different from the metal material used in the step of forming the reflection layer / pixel electrode for the pixel of the other color. A step of forming a layer-cum-pixel electrode.
A method for manufacturing a light-emitting device. The step of forming the reflective layer / pixel electrode for the at least one color pixel includes a phase shift amount φ, a refractive index of the light emitting layer n ₁ , a refractive index of the reflective layer / pixel electrode n ₂ , and the reflective layer. When the extinction coefficient of the pixel electrode is k ₂ ,
φ = tan ⁻¹ {2n ₁ k ₂ / (n ₁ ² −n ₂ ² −k ₂ ² )}
The reflective layer / pixel electrode in a pixel having a longer wavelength than the other color pixel, and a metal having a smaller phase shift φ than the reflective layer / pixel electrode in the other color pixel. The method of manufacturing a light emitting device according to claim 1, wherein the method is a step of forming the material.   3. The method of manufacturing a light emitting device according to claim 1, wherein the at least one color pixel is a red pixel or a red pixel and a green pixel.   The step of forming the reflection layer / pixel electrode for the at least one color pixel includes forming the reflection layer / pixel with a red pixel or a metal material mainly composed of Cu, Au, Ag or red pixel for the red pixel and the green pixel. The method for manufacturing a light emitting device according to any one of claims 1 to 3, wherein the method is a step of forming an electrode.   The step of forming the reflective layer / pixel electrode for the pixel of at least one color and the step of forming the vertical conductive layer for the pixel of the other color include the step of forming the reflective layer / pixel electrode and the vertical conductive layer by a damascene method. The method for manufacturing a light-emitting device according to claim 1, wherein the method is a forming step.   6. The method according to claim 1, further comprising a step of forming a diffusion prevention layer between the vertical conductive layer and the reflective layer / pixel electrode for the pixels of the other colors. Method for manufacturing the light emitting device.   7. The light emitting device according to claim 6, wherein the step of forming the diffusion prevention layer is a step of forming the diffusion prevention layer from Ti, TiN, W, Ta, Mo or an alloy containing these as a main component. Manufacturing method. The method for manufacturing a light emitting device according to claim 1, further comprising a step of forming a color filter on the counter electrode.

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