I, Michael Fletcher, declare:
`
`1. I am well versed in both the Japanese and English languages and have over 15
`years of experience translating Japanese technical documents into English.
`
`2. The following translation of the patent document JPH05-3079 to English is accurate
`and complete to the best of my knowledge.
`
`I declare under penalty of perjury under the laws of the United States of America that
`the foregoing is true and accurate.
`
`Executed this 3rd day of November 2019, at Parowan, UT
`
`Michael Fletcher
`
`IPR2020-01059
`Apple EX1004 Page 1
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`

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`(19) Japanese Patent Office
`(JP)
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`(12) Publication of Unexamined
`Patent Application (A)
`
`JPO File Number
`8815-3K
`8934-4M
`8815-3K
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`(71) Applicant
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`(71) Applicant
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`(72) Inventor
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`(72) Inventor
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`ID Number
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` A
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`(51) Int. Cl5
`H05B 33/14
`H01L 33/00
`H05B 33/26
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`(21) Application No.: 1991-
`178679
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`(22) Application Date: June 24,
`1991
`
`(11) Patent Application Disclosure
`H05-3079
`(43) Publication Date: January 8, 1993
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`Theme code (ref.)
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`FI
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`Request for Examination: Not Requested Number of Claims: 1 Total pages: 6
`000005016
`Pioneer Corporation
`1-4-1 Meguro, Meguro-ku, Tokyo
`000111889
`Pioneer Video Corporation
`2680-banchi, Nishihanawa, Tatomi-cho,
`Nakakoma-gun, Yamanashi
`MANABE, Masamichi
`c/o Pioneer Video Corporation Flagship Factory 465-
`banchi, Osato-cho, Kofushi, Yamanashi
`AMEMIYA, Kimio
`c/o Pioneer Video Corporation Flagship Factory 465-
`banchi, Osato-cho, Kofushi, Yamanashi
`
`Patent Attorney KOBASHI, Shingo (1 other)
`
`Continued on last page
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`
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`(74) Agent
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`(54) TITLE OF THE INVENTION
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`Organic EL element
`
`(57) ABSTRACT
`
`PURPOSE
`To reduce luminance and emission spectrum
`visual dependence.
`
`CONSTITUTION
`An organic EL element with a transparent
`electrode, organic EL layer, and metal electrode
`laminated in order on a transparent substrate,
`wherein the surface of the organic EL layer in
`contact with the metal electrode or the surface
`of the metal electrode that is in contact with the
`organic EL layer has been roughened.
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`CLAIMS
`[Claim 1]
`An organic EL element with a transparent electrode, organic EL layer, and metal electrode
`laminated in order on a transparent substrate, wherein the surface of the organic EL layer in
`contact with the metal electrode or the surface of the metal electrode that is in contact with the
`organic EL layer has been roughened.
`
`DETAILED DESCRIPTION OF THE INVENTION
`[0001]
`FIELD OF INDUSTRIAL USE
`The present invention is related to an organic EL element that utilizes electroluminescence
`(hereafter called EL) of substances caused by current injection and is prepared with an EL layer
`formed with a thin film of this substance and in particular where the light emitting substance is
`an organic compound.
`
`[0002]
`BACKGROUND TECHNOLOGY
`Regarding this type of organic EL element, as shown in FIG. 3, those with a two layer structure
`made up respectively of organic compounds, an EL layer 3 made up of a light emitting thin film
`and a hole transport layer 4, mutually laminated together, and arranged between a metal cathode
`1 and transparent anode 2 and those with a three layer structure as shown in FIG. 4 made up
`respectively of organic compounds, an electron transport layer 5, EL layer 3, and hole transport
`layer 4 mutually laminated together and arranged between a metal cathode 1 and transparent
`anode 2 are well known. Here, the hole transport layer 4 has a function of more readily injecting
`holes from the anode and a function of blocking electrons and the electron transport layer 5 has a
`function of more readily injecting electrons from the cathode and a function of blocking holes.
`
`[0003]
`For example, metal or metal such as various alloys with a small work function such as
`aluminum, magnesium, and indium with a thickness of roughly 1000 to 5000 angstroms can be
`used as the metal cathode 1. In addition, for example, a conductive material with a large work
`function such as Indium Tin Oxide (hereafter called ITO) or the like with a thickness of roughly
`1000 to 3000 angstroms or a metal with a thickness of 800 to 1500 angstroms can be used for the
`anode 2.
`
`[0004]
`Aluminum quinolinol complex, in other words Al oxine chelate (hereafter called Alq3),
`tetraphenyl butadiene derivative can be used as the EL layer 3. For the hole transport layer 4,
`compounds such as triphenyldiamine derivative N, N′-diphenyl-N, N′-bis (3methylphenyl) -1,1′-
`biphenyl-4,4′-diamine (hereinafter referred to as TPD) can preferably be used, as CTM (Carrier
`Transporting Materials) and these can be used alone or as a mixture.
`
`[0005]
`For example, oxadiazole derivatives (PBD) and the like can be used as the as the electron
`transport layer. In these organic EL elements, a glass substrate 6 is arranged on the outside of the
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`transparent electrode 2 and excitons are generated from the recombining of electrons injected
`from the metal cathode 1 and holes injected from the transparent anode 2 onto the EL layer 3.
`Excitons on the EL layer near the boundary layer with the hole transport layer emit light in a
`radiation and deactivation process. This light is discharged externally through the transparent
`anode 2 and glass substrate 6 (Japanese Unexamined Patent Application S59-194393 and
`Japanese Unexamined Patent Application S63-295695).
`
`[0006]
`THE ISSUE(S) THAT THIS INVENTION INTENDS TO RESOLVE
`However, as a result of research of the film thickness of the EL layer of a two-layer structure
`organic EL element and emission spectrum, luminance, and viewing angle, the inventors learned
`that luminance has EL layer thickness dependence and viewing angle dependence. In other
`words, emission spectrum and luminance of the organic EL element and glass substrate 6 as
`shown in FIG. 5 changes depending on the viewing angle of the viewer.
`
`[0007]
`Light emitted from one point of emission source P within the EL layer includes light from two
`sources, path A of light directly impinging on the substrate 6 in the drawings and path B of light
`reflecting off the metal electrode 1 and impinging on the substrate 6. The light from these two
`paths have light path difference L given by equation 1 and furthermore phase difference ηy given
`by equation 2 and mutually interfere (in both equations, n is the refractive index of the EL layer
`3, y is the distance from the light source P to the metal electrode 1, θ is the viewing angle from
`normal on the display surface in the EL layer, and λ indicate respective wavelengths. Same
`hereinafter).
`
`[0008]
`Equation 1
`
`
`
`
`
`[0009]
`Equation 2
`
`
`
`
`
`Therefore, intensity I as a result of interference can be expressed as in equation 3.
`[0010]
`Equation 3
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`[0011]
`As shown in FIG. 6, the light intensity f(y) distribution in the EL layer at the boundary layer of
`the hole transport layer 4 decreases with increased directedness towards the metal electrode 1
`and an exponential function distribution related to film thickness can be expressed as equation 4
`and for EL thickness overall, can be normalized as equation 5 (in both equations d is distance
`from the light source to the metal electrode, ε is the light source intensity distribution parameter,
`and k is a constant. Same hereinafter).
`
`[0012]
`Equation 4
`
`[0013]
`Equation 5
`
`[0014]
`The intensity distribution F(λ) of the emission spectrum of the light source itself can be exhibited
`as a function of wavelength λ specific to the light source body. Therefore, the emission intensity
`T (λ，θ，d) of the EL element actually observed by the viewer can be given by equation 6.
`
`[0015]
`Equation 6
`
`[0016]
`Here, to confirm the emission intensity T (λ，θ，d) of the EL element, an organic EL element
`containing an EL layer made up of Alq3 with a film thickness d of 6000 angstroms was prepared
`and a test was performed regarding emission intensity of viewing angles from 0° to 75°. FIG. 7
`shows emission intensity distribution relative to emission wavelength. Therefore, the emission
`intensity distribution was confirmed to nearly match with the emission intensity T (λ，θ，d)
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`from equation 6, described above. As is clear from the drawing, from the viewpoint of the
`viewer, the colors appear to change sequentially based on the direction of viewing the EL
`element display surface of viewing angle from 0° to 75°.
`
`[0017]
`Further, the visual sensitivity characteristic E (λ) of a viewer or photodetector that is sensitive to
`a specific value relative to the wavelength λ is considered with regards to practical use. For
`example, assuming that the visibility characteristics E (λ) is a normal distribution, the EL
`element luminance characteristics L (d) within the sensitivity characteristics can be expressed as
`a function of d as in equation 7.
`
`[0018]
`Equation 7
`
`
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`
`
`[0019]
`FIG. 8 shows the luminance/current characteristics of the EL layer (θ = 0, n = 1.7) made up of
`Alq3 relative to thickness for the case where the thickness thereof is changed from
`approximately 0 angstrom to 8000 angstrom and this attenuation curve shows the film thickness
`dependence of luminance in the organic EL element.
`
`[0020]
`As has been described above, color (emission spectrum) and luminance of the organic EL
`element changes with viewing angle and luminance changes with variability in the film thickness
`so when displaying color, changes of color and luminance with viewing angle are very
`inconvenient for a display and improvement becomes a major issue.
`
`[0021]
`In light of these types of circumstances, an objective of the present invention is to provide an
`organic EL element with reduced luminance and emission spectrum visual angle dependence.
`
`[0022]
`MEANS FOR SOLVING THE VARIOUS ISSUES
`The present invention is fruition based on the knowledge described above and is an organic EL
`element with a transparent electrode, organic EL layer, and metal electrode laminated in order on
`a transparent substrate, wherein the surface of the organic EL layer in contact with the metal
`electrode or the surface of the metal electrode that is in contact with the organic EL layer has
`been roughened.
`
`[0023]
`FUNCTION
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`With the surface light emission device of the present invention, regarding the organic EL layer
`made up of a hole transport layer and light emission layer, luminance changing with film
`thickness, emission spectrum and luminance changes based on viewing angle, and reduced
`luminance based on viewing angle were discovered through actual testing by the inventors.
`Furthermore, they discovered that these types of changes can be explained based on an
`interference model.
`
`[0024]
`Therefore, roughening of the surface of the organic EL layer in contact with the metal electrode
`or the surface of the metal electrode in contact with the organic EL layer causes slight
`differences in the light path from light sources within the light emission layer causing averaging
`of the interference effect and reducing angle dependence and film thickness dependence.
`
`[0025]
`EMBODIMENTS
`An embodiment of the present invention will be described in detail below based on the drawings.
`Furthermore, for the drawings described below, any parts that are shared with FIG. 3 will use the
`same symbols, and any repeated description will be omitted thereof.
`
`[0026]
`FIG. 1 shows an embodiment of the organic EL element of the present invention being applied to
`a 2 layer structure, with a transparent electrode 2 of In2O3 or O2, or the like, a hole transport
`layer 4 made up of a triphenyldiamine derivative (TPD) that makes up an organic EL layer, a
`light emitting layer 3 made up of an aluminum quinolinome complex (Alq3), and a metal
`electrode 1 made up of Mg-Al or the like formed in order on the rough surface of a glass
`substrate 6.
`
`[0027]
`FIG. 2 shows a magnification of the rough surface part as described above, in that the maximum
`height of the surface which was made into a rough surface is roughly 1 μm, and intervals L
`between the peaks of the rough surface are preferably around 3 μm. In addition, an organic EL
`element that is roughened as described above is prepared as follows.
`
`[0028]
`First, the surface of a glass substrate 6 is processed using a corrosion process with a chemical
`that has a corrosive action, such as a fluorate or the like, for example, or by a sand blasting
`process, or the like. At this time, the maximum height of the roughened surface and the intervals
`L between peaks are 1 μm and 3 μm, respectively. These processing methods are the same
`methods as the manufacturing method for what is a called frosted glass.
`
`[0029]
`Next, a layer of the transparent electrodes 2 with an ITO membrane thickness of 1,000 angstroms
`is formed with spattering on the surface of the glass substrate 6 which underwent the roughening
`process. When forming the layer of the transparent electrodes 2, a gaseous mixture of Ar and O2
`is used, and performed in a vacuum of 10-3 Torr.
`
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`[0030]
`When forming of the transparent electrodes 2 is completed, TPD and Alq3 are deposited using
`resistive heating vapor deposition on the surface thereof under a vacuum from 10-6 to 10-7 Torr in
`order, forming the hole transport layer 4 and the light emitting layer 3 respectively, both at 500
`angstoms. When forming of the light emitting layer 3 is complete, Mg-Al is vapor deposited on
`the top thereof in a vacuum of 10-6 to 10-7 Torr, forming the metal electrodes 1.
`
`[0031]
`In this manner, the interface of each layer is roughened to a degree as described above. As a
`result, there are different optical path variations from each of the light emitting points in the light
`emitting layer when seen from certain visual angles and is not constant. Therefore, interference
`effect is averaged, and changes in visual angle dependence in luminance and the light emitting
`spectrum and variation in membrane thickness are suppressed.
`
`[0032]
`Furthermore, specular reflection is decreased, improving contrast. Moreover, with the present
`embodiment, by subjecting the surface of the glass substrate 1 to processing to increase
`roughness, the roughness of the surface thereof in contact with the light emitting layer and metal
`electrode is increased; however, the present invention is not limited to this example and only
`roughening the surface in contact with the metal electrode of the light emitting layer is also
`feasible.
`
`[0033]
`Furthermore, the present invention is not restricted to a two-layer structure as described in the
`embodiment above, and interfaces between layers for a three-layer structure can be roughened as
`well, as shown in FIG. 4.
`
`[0034]
`EFFECT OF THE INVENTION
`As described above, with the organic EL element of the present invention, interference effect is
`averaged and angle dependence and membrane thickness dependence is reduced by roughening
`the surface in contact with the metal electrode of the organic EL layer or the surface in contact
`with the organic EL layer of the metal electrode to cause differences in optical path variations
`from light emitting points inside the light emitting layer and thus reduction in luminance based
`on viewing angle can be prevented.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a drawing showing an embodiment applying the present invention to an organic EL
`element with a two-layer structure.
`FIG. 2 is a drawing showing a part of the roughened surface of the organic EL element as shown
`in FIG. 1.
`FIG. 3 is a structural drawing showing an organic EL element with a two-layer structure.
`FIG. 4 is a structural drawing showing an organic EL element with a three-layer structure.
`FIG. 5 is a partial enlarged cross-section drawing describing light interference of an organic EL
`element with a two-layer structure.
`
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`FIG. 6 is a graph describing the membrane thickness light emitting strength distribution of the
`EL layer of an organic EL element with a two-layer structure.
`FIG. 7 is a graph describing the wavelength light emitting strength distribution of the EL layer of
`an organic EL element with a two-layer structure.
`FIG. 8 is a graph describing the single-layer membrane thickness luminance attenuation curve of
`the EL layer of an organic EL element with a two-layer structure.
`
`EXPLANATION OF CODES
`1 Metal electrodes
`2 Transparent electrodes
`3 EL layer
`4 Hole transport layer
`5 Electron transport layer
`6 Glass substrate
`
`FIG. 1
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`FIG. 2
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`FIG. 3
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`Light emission
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`FIG. 4
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`Light emission
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`FIG. 5
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`EL layer film thickness
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`FIG. 6
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`Light emission intensity
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`View angle 0 degrees
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`View angle 75 degrees
`
`FIG. 7
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`Light emission intensity
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`Wavelength (nm)
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`FIG. 8
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`Intensity (a.u)
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`EL layer film thickness Å
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`Continued from first page
`
`(72) Inventor
`TANAKA, Yukio
`c/o Pioneer Video Corporation Flagship Factory 465-banchi, Osato-cho, Kofushi, Yamanashi
`
`(72) Inventor
`YONOMOTO, Keiya
`c/o Pioneer Video Corporation Flagship Factory 465-banchi, Osato-cho, Kofushi, Yamanashi
`
`
`
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`IPR2020-01059
`Apple EX1004 Page 15
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