JP2009117758A - Organic el light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL light-emitting element, making compatible both the high bright-place contrast and high luminance by RGB pixels, and which can be manufactured at low cost. <P>SOLUTION: The organic EL light-emitting element has at least a first reflecting film 107 on one side via an organic light-emitting layer 106 and has at least a transparent electrode 105, a light guide film 104 and a second reflecting film 103 on the other side. The second reflecting film 103 has an aperture 110 for radiating light, the area of the aperture 110 is smaller than the area of the organic light-emitting layer 106, the light-extracting side of the second reflecting film 103 is covered with a light absorbing film 102, excluding the aperture 110, and the thickness of the light guide film is 0.5 times or more for the coherent distance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic EL light emitting device.

  Organic EL light-emitting elements generate excitons by sandwiching a film containing an organic compound between an anode and a cathode, and injecting holes (holes) and electrons from each electrode. It is an element that utilizes light emitted when returning.

In 1987, Kodak's research (Non-Patent Document 1) uses an alloy of ITO for the anode and magnesium silver for the cathode. Tris (8-quinolinolato) aluminum is used for the electron transport material and the light emitting material. Triphenylamine derivatives are used for the hole transport material. In this research, light emission of about 1000 cd / m ² is reported at an applied voltage of about 10 V in an element having a function separation type two-layer structure.

  In addition, by changing the type of the fluorescent organic compound, light emission from ultraviolet to infrared is possible, and recently, various compounds have been actively researched.

  Furthermore, in addition to the organic EL light emitting device using the low molecular material as described above, an organic EL light emitting device using a conjugated polymer has been reported by a group of Cambridge University. In this report, light emission is confirmed in a single layer by forming a film of polyphenylene vinylene (PPV) in a coating system.

  In this way, organic EL light-emitting elements can be made into light-emitting devices with a low applied voltage and high brightness, high-speed response, thinness, and light weight, suggesting the possibility of a wide range of applications, especially as display applications Attention has been paid.

  A cross-sectional view of a conventional organic EL light emitting device is shown in FIG. A structure in which an organic compound layer 403 is sandwiched between a light-transmissive first electrode 402 and a light-reflective second electrode 404, and light emitted from the organic compound layer 403 is extracted from a light extraction surface on the transparent electrode side; It has become. However, since the external light 405 incident from the light extraction surface is reflected by the second electrode 404 and is emitted again from the light extraction surface, the organic EL display device in which the organic EL light emitting elements are arranged two-dimensionally has a bright contrast. The display quality was bad.

  In order to solve this problem, Patent Document 1 discloses a high-contrast layer that reflects internal light and absorbs external light, has a slit-like or dot-like light transmission hole, or has an island shape itself. The structure which has is disclosed. It is possible to suppress external light reflection and have a good contrast.

JP-A-11-265791

  The invention of Patent Document 1 is an invention excellent in improving contrast, but there is a problem that it is difficult to achieve both contrast and brightness in all of the R pixel, G pixel, and B pixel. This is because the distance between the light reflection layer of the high contrast enhancement layer and the second electrode for efficiently repeating reflection between the light reflection layer of the high contrast enhancement layer and the second electrode is R pixel, G This is because the pixel and the B pixel are different.

  The above problem can be solved by making the distance between the light reflection layer of the high contrast layer and the second electrode different between the R pixel, the G pixel, and the B pixel, but in this case, the manufacturing cost greatly increases. Occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an organic EL light-emitting device that can achieve both high contrast and brightness in RGB pixels and can be manufactured at low cost.

As means for solving the above problems, the present invention provides:
An organic EL light emitting device having at least a first reflective film on one side and at least a transparent electrode, a light guide film, and a second reflective film on the other side with an organic light emitting layer interposed therebetween,
The second reflecting film has an opening for emitting light, the area of the opening is smaller than the area of the organic light emitting layer, and the light extraction side of the second reflecting film is light except for the opening. The light guide film is covered with an absorption film, and the thickness of the light guide film is 0.5 times or more the coherence distance.

  According to the present invention, it is possible to provide an organic EL light emitting element that can achieve both high contrast and brightness in RGB pixels and can be manufactured at low cost.

  FIG. 1 is a schematic cross-sectional view of an example of a subpixel including an organic EL light emitting element and a drive circuit of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a part of the sub-pixel of FIG. 1 in more detail.

  The organic EL light emitting element shown in FIG. 1 is a bottom emission type element driven by an active matrix. In FIG. 1, reference numeral 1001 denotes a region made of an organic EL light emitting element, and reference numeral 1002 denotes a region made of a circuit for driving the organic EL light emitting element 1001, which is formed on a substrate 101 such as glass. Here, a method for forming the organic EL light emitting element 1001 will be described in which an organic light emitting layer 106 is applied to a region sandwiched between banks (barriers) 109 by a nozzle method, an ink jet method, or the like. Other production methods such as a photothermal transfer method may be used.

  An organic EL light emitting element 1001 has a single or multilayer organic light emitting layer 106, a cathode 107 serving as a first reflective film on one side of the organic light emitting layer 106, and an anode serving as a transparent electrode on the other side. 105, a light guide film 104, and a second reflective film 103. The light absorption film 102 is provided on the light extraction side of the second reflective film 103, that is, on the opposite side of the light guide film 104 with respect to the second reflective film 103. Incidentally, reference numeral 111 denotes an insulating layer for insulating a drive circuit and the like from the light absorption film 102, and is an unnecessary layer when the light absorption film 102 is formed of an insulator.

  In the configuration shown in FIGS. 1 and 2, the second reflective film 103, the light absorption film 102, and the insulating film 111 have an opening 110 for radiating light emitted from the organic light emitting layer 106 to the outside. The light absorption film 102 is preferably a film having a light absorption rate as large as possible with respect to visible light, and a black resin, a Cr thin film, or a black indium oxide thin film used for the black matrix is preferable.

The second reflective film 103 is a film having a high reflectivity with respect to the light emitted from the organic light emitting layer 106. For example, Al or the like is formed by vapor deposition, sputtering, or the like. At this time, it is preferable that the second reflection film 103 is formed in a form on the side surface of the bank 109 so that the light guide film 104 can be partitioned between elements (between subpixels). The light guide film 104 is a film that is small enough to absorb light emitted from the organic light emitting layer 106, and is made of an inorganic dielectric such as SiN or SiO ₂ or a resin such as acrylic. The anode 105 is a transparent conductor such as ITO, and is formed by a sputtering method or the like. The circuit 108 and the anode 105 are electrically connected via a second reflective film 103 formed on the side surface of the bank. The cathode 107 is a metal such as Al, for example, and is formed by a vapor deposition method or the like.

  The organic light emitting layer 106 includes at least a light emitting layer related to light emission. The organic light-emitting layer 106 can emit light even with a single light-emitting layer, but in order to improve hole and electron injection properties, a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer are used. A structure in which the light emitting layers are sandwiched may be used. Further, a barrier layer or the like may be included to balance the density of holes and electrons, or to prevent the material of each layer from moving to another layer and degrading the device. In addition, the light emitting layer may be made of a fluorescent material that emits fluorescence, or may be doped with a phosphorescent material that generates phosphorescence as a guest.

  In the organic EL light emitting device having the above-described structure, light is emitted by recombination of holes injected from the anode 105 side and electrons injected from the cathode 107 side in the light emitting layer. At this time, part of the light emitted from the organic light emitting layer 106 is directly emitted to the outside through the opening 110 provided in the second reflective film 103, the light absorbing film 102, and the insulating layer 111. A part of the light emitted from the organic light emitting layer 106 is repeatedly reflected between the second reflective film 103 and the cathode 107, and then is reflected on the second reflective film 103, the light absorbing film 102, and the insulating layer 111. The light is radiated to the outside through the provided opening 110.

  Here, if the light emitted from the organic light emitting layer 106 interferes when it is repeatedly reflected between the second reflective film 103 and the cathode 107, the thickness of the light guide film 104 is reduced in order to efficiently repeat the reflection. The thickness must be made different in RGB. This makes it difficult to create a full-color display device. In order to avoid this, the light guide film 104 is formed so thick that the light emitted from the organic light emitting layer 106 hardly causes interference. The coherence distance with which light interferes can be expressed by equation (1).

Coherent distance = λ ² / Δλ (1)

  In equation (1), λ is the center wavelength of the emission spectrum, and Δλ is the half width of the emission spectrum. In order to prevent the light emitted from the organic light emitting layer 106 from causing interference, it is sufficient that the coherence distance is exceeded when the reciprocating distance of the light guide film 104 is advanced. The film thickness is made 0.5 times or more of the interference distance.

  The bright place contrast is I / A where I is the light emission intensity of the element and A is the reflection intensity of external light. In the organic EL light emitting device of the present invention, if the loss due to reflection or transmission is ignored, all the light other than being confined in the device by total reflection is radiated to the outside from the opening 110. It becomes the same intensity as the conventional organic EL light emitting element. On the other hand, the reflection intensity of external light is such that the ratio of the area B of the opening 110 provided in the second reflection film 103, the light absorption film 102, and the insulating layer 111 to the area C of the light emitting portion is α = B / C. If the external light reflection at the absorption film 102 is substantially zero, it is α times that of the conventional organic EL light emitting device shown in FIG. That is, in the organic EL light emitting device of the present invention, the bright place contrast is ideally 1 / α times that of the conventional one.

  Thus, the smaller the aperture 110 is, the greater the effect of improving the bright spot contrast is. However, when the aperture 110 is too small, the luminance change due to the radiation angle increases due to diffraction, and the image quality when the display device is configured deteriorates. To do. Accordingly, it is desirable that the opening 110 has a shape that has a length of 10 times or more of the wavelength even at the narrowest portion. Specifically, it is desirable to form an opening such as a circle having a diameter of 8 μm or more, a square having a side of 8 μm or more, or a rectangle having a short side of 8 μm or more. Also, ideally, the smaller the aperture ratio, the better the contrast. However, in reality, the loss of light quantity due to reflection and transmission cannot be ignored, and the light quantity loss should be 50% or less when the aperture ratio is less than 0.1. It is difficult. Therefore, it is desirable to set the aperture ratio to 0.1 to 0.8.

  The organic EL light emitting device having the above configuration has the opening 110 and the light guide film has a thickness that hardly causes interference, so that both high contrast and brightness can be achieved, and a clear color image is displayed in the bright place. it can. Moreover, it can be manufactured at low cost.

  In addition, although the emitted light has shown what is called a bottom emission type which goes to the board | substrate 101 side, of course, you may be a top emission type emitted on the opposite side to a board | substrate. In that case, the arrangement of the anode and the cathode is reversed, or the opposite electrode is provided with transparency.

  The organic EL light emitting element 1001 is mounted as a single light emitting point, and a display device having a plurality of circuits 1002 for driving the organic EL light emitting element 1001, an illumination device including the display device, and an electrophotographic image forming apparatus It can be an exposure light source.

  The circuit 1002 includes a driver transistor (Dr-Tr) 1009 for supplying current to the organic EL light emitting element 1001. Furthermore, a switch transistor (for switching whether to allow or not to write information by a storage capacitor unit 1011 for writing the value of display information sent through the data line 1010 and a selection line (not shown). Sw-Tr) 1012.

  FIG. 3 is a diagram for explaining the operation of the circuit for driving the organic EL light emitting device according to the present invention shown in FIG. Although the circuit will be described with respect to a known programming scheme, the circuit of the present invention is not limited to this. In FIG. 3, a portion 1013 surrounded by a broken line corresponds to one pixel. The pixel 1013 includes an organic EL light emitting element 1001, Dr-Tr 1009, a storage capacitor 1011, and Sw-Tr 1012.

  The selection line 1014 is connected to the gate of the Sw-Tr 1012, and the selection of whether or not to allow writing of information is performed according to the signal of the selection line 1014. When the writing of information is permitted, the Sw-Tr 1012 enters the On state and transmits the value of the display information sent from the data line 1010 to the gate of the Dr-Tr 1009 and the storage capacitor 1011. The value of the display data is a voltage value corresponding to the light emission luminance of the organic EL light emitting element 1001, and the voltage value applied to the gate of the Dr-Tr 1009 is written and stored in the storage capacitor 1011.

  The source of the Dr-Tr 1009 is connected to the power supply 1015 via the power supply line 1016, and supplies a current amount according to the voltage applied to the gate to the organic EL light emitting device 1001. In the organic EL light emitting device 1001, holes and electrons are injected according to the amount of current, and light is emitted by recombination within the organic light emitting layer 106.

  In accordance with a signal of the selection line 1014 connected to each pixel, information writing permission is sequentially switched to another pixel, and display information is written to a plurality of pixels. Once information is written to the storage capacitor 1011, the value of the storage capacitor 1011 is held until the next selection and new information is written, and light emission according to the value is continuously emitted from the organic EL light emitting element. .

  FIG. 4 is a schematic diagram illustrating a display device in which a plurality of pixels 1013 illustrated in FIG. 3 are two-dimensionally arranged. Note that the power supply and the power supply line are not shown in the figure. In FIG. 4, a plurality of selection lines 1014 are connected to a selection line driving circuit 1018 and are driven so that one column of pixels 1013 is sequentially selected for each column. The plurality of data lines 1010 are connected to the data line driving circuit 1017, and display information is transmitted to each of the selected horizontal row of pixels, and the information is written to the storage capacitors in the respective pixels. .

  Information is written sequentially for each column, for example, repeatedly from the upper column to the lower column over the entire surface of the display device. The writing cycle at this time is 60 times per second in television broadcasting or the like, and moving images can be smoothly displayed by switching the display of pixels at a speed that cannot be detected by the eyes. .

  FIG. 5 is a diagram showing an overview of the display device of the present invention shown in FIG. In FIG. 5, the display device 1019 includes a display region 1020 in which pixels are arranged two-dimensionally, a selection line driver circuit 1018 that drives a selection line, and a data line driver circuit 1017 that drives a data line. Further, it includes an interface control circuit 1021 that transmits and receives information to and from the control unit of the application apparatus, and a connection unit 1022 that connects signal lines and the like. Depending on the application device, the size of each pixel and the number of pixels arranged in a two-dimensional manner are determined, and the light emission luminance and display cycle of the pixels are also determined according to image quality requirements.

  FIG. 6 is a diagram showing a video display device as an example to which the display device of the present invention shown in FIG. 5 is applied. In FIG. 6, reference numeral 1023 denotes a housing of the video display device of the present invention. In addition to the display device 1019 shown in FIG. 5, the housing 1023 includes a television broadcast receiving circuit unit, an audio output unit, a control unit that controls the video display device, and the like. Broadcast video can be displayed in the display area 1020.

  When an organic EL light-emitting element is used as a pixel, self-emission occurs, so that contrast, which is a ratio between black display and white display, is large, and high-quality display can be performed. In addition to video display, it can of course be used as a monitor for control devices such as computers.

  FIG. 7 is a diagram showing a portable device as an example to which the display device of the present invention shown in FIG. 6 is applied. Here, a portable phone will be described as an example. However, a still or moving image input device such as a digital still camera or a digital video camera, a portable information input / output device, or a portable game. It can also be applied to devices.

  In FIG. 7, reference numeral 1024 denotes a casing of the portable device of the present invention. In addition to the display device 1019 shown in FIG. 5, the housing 1024 includes a number input unit, a small video input unit, a voice and video transmission / reception unit, a control unit for controlling the portable device, and the like. . In accordance with a user instruction, the content input from the input unit, the video captured by the video input unit, or the received video can be displayed in the display area 1020.

  Similar to the video display device described above, when an organic EL light emitting element is used as a pixel, self-emission occurs, so that the contrast, which is the ratio of black display to white display, is large, and high-quality display can be performed. Furthermore, by making the background a screen having a lower luminance than a liquid crystal screen, power consumption can be reduced, which is suitable for application to a portable device.

  Hereinafter, the present invention will be described in more detail with reference to examples.

<Example 1>
The subpixels shown in FIGS. 1 and 2 including the organic EL light emitting device of the present invention were prepared as follows. The size of the created subpixel was 160 μm × 480 μm, and the size of the light emitting portion in the subpixel was 140 μm × 240 μm.

  First, a black indium oxide layer having a thickness of 200 nm was formed on a glass substrate 101 having a thickness of 0.7 mm by sputtering deposition using an indium oxide target, so that a light absorption film 102 was formed. At this time, the film was formed by adjusting the oxygen concentration in the sputtering gas so that the indium oxide thin film was black.

  An insulating layer 111 made of SiN was formed to a thickness of 300 nm by plasma CVD. Next, a drive circuit 108 for an organic EL light emitting element was formed on a part of the insulating layer 111. As the drive circuit 108, the circuit shown in FIG. 3 is made of an amorphous silicon TFT. Next, in order to create the bank 109, an acrylic resin layer was formed to a thickness of 7 μm, and this acrylic resin layer was processed by photolithography to create the bank 109. Next, a second reflective film 103 of Al was formed by sputter deposition and photoengraving. The thickness of the created second reflective film 103 was 100 nm at the bottom surface. Next, the light absorbing film 102, the insulating layer 111, and the second reflective film 103 were processed by photolithography to form an opening 110 having a diameter of 100 μm. Next, the SiN film formed by plasma CVD was processed by photolithography to form a light guide film 104 having a thickness of 3.5 μm.

  An anode 105 was formed by forming ITO with a film thickness of 200 nm and processing the film by photoengraving. The drain of the Dr-Tr 1009 and the anode 105 are connected via the second reflective film 103. Next, an organic light emitting layer 106 was formed by laminating a hole injection layer and an orange light emitting layer. As the hole injection layer, PEDOT / PSS was continuously applied using a dispenser device. The application conditions are as follows. Using a Teflon (registered trademark) machined metal needle with a diameter of 100 μm for a width of 140 μm between the banks 109, the distance between the needle and the surface to be coated is 30 μm in air, and the relative speed between the needle and the substrate 101 is The coating was continuously performed at 450 mm / sec. After coating, a 30-nm-thick hole injection layer was formed by baking at 200 ° C. for 10 minutes using a hot plate. As the orange light-emitting layer, a dispenser device is used between the banks 109 with 1 wt% of a solution in which polyparaphenylene vinylene derivative poly [2-methoxy, 5- (2′-ethylhexoxy) -1,4-phenylene vinylene] is dissolved in tetralin. And applied. The application conditions are as follows. Teflon (registered trademark) processed metal needle with a diameter of 100 μm was used, and the distance between the needle and the surface to be coated was continuously applied in nitrogen at a distance of 30 μm and the relative speed between the needle and the substrate 101 was 300 mm / sec. . After coating, an orange light emitting layer having a thickness of 80 nm was formed by baking at 150 ° C. for 30 minutes in a nitrogen atmosphere using a hot plate.

After the organic light emitting layer 106 was formed, the cathode 107 was formed by vapor deposition and sputtering. As the electrode material for the cathode 107, Cs ₂ CO ₃ and Al were used. The film thickness in this example was 3 nm for Cs ₂ CO ₃ and 100 nm for Al.

  As described above, the organic EL light emitting device of Example 1 was produced.

<Comparative Example 1>
As Comparative Example 1, a subpixel including an organic EL light emitting element having the configuration shown in FIG. 8 was prepared as follows. The size of the created subpixel was 160 μm × 480 μm as in Example 1, and the size of the light emitting portion in the subpixel was 140 μm × 240 μm.

  First, a 200 nm thick black indium oxide layer was formed on a 0.7 mm thick glass substrate 501 by sputter deposition using an indium oxide target in the same manner as in Example 1, and then processed by photolithography. Thus, a light absorption film 508 was formed. Next, an insulating layer 509 made of SiN was formed to a thickness of 300 nm by plasma CVD. Next, a driving circuit 506 for the organic EL light emitting element was formed on a part of the insulating layer 509. The drive circuit 506 was formed by using amorphous silicon TFTs as shown in FIG. Next, an acrylic resin layer was formed as a planarizing layer 507 on the driving circuit 506 so as to have a thickness of about 2 μm. Next, ITO was formed into a film having a thickness of 200 nm and processed by photolithography to form an anode 502. The drain of the Dr-Tr 1009 and the anode 502 are connected via a via (not shown). Next, a polyimide resin layer was formed to a thickness of 3 μm and processed by photographic touch to create a bank 505.

  Next, an organic light emitting layer 503 was formed by laminating a hole injection layer and an orange light emitting layer. As the hole injection layer, PEDOT / PSS was continuously applied using a dispenser device. The application conditions are as follows. Using a Teflon (registered trademark) machined metal needle with a diameter of 100 μm for a width of 140 μm between the banks 505, the distance between the needle and the coating surface in the atmosphere is 30 μm, and the relative speed between the needle and the substrate 501 is The coating was continuously performed at 450 mm / sec. After coating, a 30-nm-thick hole injection layer was formed by baking at 200 ° C. for 10 minutes using a hot plate. As the orange light-emitting layer, a dispenser device is used between banks 505 with a solution in which polyparaphenylene vinylene derivative poly [2-methoxy, 5- (2′-ethylhexoxy) -1,4-phenylene vinylene] is dissolved in tetralin at 1 wt%. And applied. The application conditions are as follows. Using a Teflon (registered trademark) machined metal needle with a diameter of 100 μm, the distance between the needle and the surface to be coated in nitrogen was continuously applied at 30 μm and the relative speed between the needle and the substrate 501 was 300 mm / sec. . After coating, an orange light emitting layer having a thickness of 80 nm was formed by baking at 150 ° C. for 30 minutes in a nitrogen atmosphere using a hot plate.

After forming the organic light emitting layer 503, the cathode 504 was formed by vapor deposition and sputtering. As the electrode material for the cathode 504, Cs ₂ CO ₃ and Al were used, and the film thickness was ₃ nm for Cs ₂ CO ₃ and 100 nm for Al.

  As described above, an organic EL light emitting device of Comparative Example 1 was prepared.

The organic EL light emitting devices of Example 1 and Comparative Example 1 thus produced were caused to emit light by flowing a current of 4 μA per subpixel. At this time, the light emission luminance of the organic EL light emitting device of Example 1 was 180 cd / m ² , and the light emission luminance of the organic EL light emitting device of Comparative Example 1 was 200 cd / m ² . That is, the organic EL light-emitting device of Example 1 had a luminance of 90% as compared with the organic EL light-emitting device of Comparative Example 1, and the luminance was reduced to such a level that there was no practical problem. On the other hand, the bright place contrast under the external light of 150 lx was 11: 1 for the organic EL light emitting device of Comparative Example 1, whereas the organic EL light emitting device of Example 1 was 42: 1, which was about 4 times. Improved.

<Example 2>
FIG. 9 is a schematic cross-sectional view of a subpixel including the organic EL light emitting device of the second embodiment of the present invention.

  The subpixel shown in FIG. 9 was created as follows. The size of the created subpixel was 160 μm × 480 μm, and the size of the light emitting portion in the subpixel was 140 μm × 460 μm.

  First, an organic EL light-emitting element drive circuit 210 was formed on a glass substrate 201 having a thickness of 0.7 mm. As the drive circuit 210, the circuit shown in FIG. 3 is made of an amorphous silicon TFT. Next, an acrylic resin layer as the planarizing layer 211 was formed on the driving circuit 210 so as to have a thickness of about 2 μm. Next, Al was formed into a film having a thickness of 100 nm and processed by photolithography to form a first reflective film 208. Next, ITO was formed into a film with a thickness of 200 nm and processed by photolithography to form an anode 207. The drain of the Dr-Tr 1009 and the anode 207 are connected via a via (not shown). Next, a polyimide resin layer was formed to a thickness of 3 μm and processed by photographic touch to create a bank 209.

  Next, an organic light emitting layer 206 was formed by laminating a hole injection layer and an orange light emitting layer. As the hole injection layer, PEDOT / PSS was continuously applied using a dispenser device. The application conditions are as follows. Using a Teflon (registered trademark) machined metal needle with a diameter of 100 μm for a width of 140 μm between the banks 209, the distance between the needle and the coating surface in the atmosphere is 30 μm, and the relative speed between the needle and the substrate 201 is The coating was continuously performed at 450 mm / sec. After coating, a 30-nm-thick hole injection layer was formed by baking at 200 ° C. for 10 minutes using a hot plate.

  As the orange light emitting layer, a dispenser device is used between the banks 209 with a solution obtained by dissolving 1 wt% of polyparaphenylene vinylene derivative poly [2-methyoxy, 5- (2′-ethylhexyoxy) -1,4-phenylene vinylene] in tetralin. And applied. The application conditions are as follows. Using a Teflon (registered trademark) processed metal needle with a diameter of 100 μm, the distance between the needle and the surface to be coated was continuously applied in nitrogen at a distance of 30 μm and the relative speed between the needle and the substrate 201 was 300 mm / sec. . After coating, an orange light emitting layer having a thickness of 80 nm was formed by baking at 150 ° C. for 30 minutes in a nitrogen atmosphere using a hot plate.

After forming the organic light emitting layer 206, the cathode 205 was formed by vapor deposition and sputtering. The cathode 205 was formed by laminating Cs ₂ CO ₃ with a thickness of 3 nm, Al with a thickness of 4 nm, and ITO with a thickness of 100 nm.

  Next, a SiN film was formed by plasma CVD to form a light guide film 204 having a thickness of 4 μm. Next, an Al second reflective film 203 was formed to a thickness of 100 nm by sputter deposition and photoengraving. Next, a black resin layer for a black matrix was formed to a thickness of 3 μm, and then processed by photographic touch to create a light absorbing film 202.

When this organic EL light emitting device was illuminated with a luminance of 200 cd / m ² , the bright place contrast under an external light of 150 lx was 80: 1.

<Example 3>
FIG. 10 is a schematic cross-sectional view of a subpixel including the organic EL light emitting device of the third embodiment of the present invention.

  In the same manner as in Example 2, an organic EL light emitting element driving circuit 210, a planarizing layer 211, a first reflective film 208, an anode 207, a bank 209, an organic light emitting layer 206, a cathode 205, and a light guide film are formed on a substrate 201. 204, the 2nd reflection film 203, and the light absorption film 202 were produced.

  Next, after forming a black resin layer for black matrix with a thickness of 2 μm, the black matrix 212 was formed by processing by photolithography. Next, an orange color resist having a thickness of 2 μm was formed, and then processed by photoengraving to form a color filter 213.

As described above, an orange single color display device was produced. When this display device was illuminated with a luminance of 200 cd / m ² , the bright place contrast under an external light of 150 lx was 200: 1.

  In this example, a monochromatic display device was created in order to verify the bright place contrast improvement effect of the present invention. However, it is obvious that a full-color display device can be configured by arranging organic light emitting layers that emit light in red, green, and blue in a matrix and arranging color filters corresponding to the respective emission colors.

<Example 4 and Example 5>
Example except that the thickness of the light guide film 104 was changed to 3.4 μm and the organic EL light emitting device of Example 4 prepared in the same manner as in Example 1 and the thickness of the light guide film 104 was changed to 3.6 μm. An organic EL light emitting device of Example 5 prepared in the same manner as in Example 1 was prepared. These were compared with the organic EL light-emitting device of Comparative Example shown below together with the organic EL light-emitting device of Example 1.

<Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, Comparative Example 7>
The thickness of the light guide film 104 was 0.1 μm, 0.2 μm, 0.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, respectively, and the others were prepared in the same manner as in Example 1, Comparative Example 2 and Comparative Organic EL light emitting devices of Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7 were prepared.

  A current of 4 μA per subpixel was passed through the organic EL light-emitting devices of Example 1, Example 4, Example 5, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 5, Comparative Example 6, and Comparative Example 7. The brightness and the contrast in the light place were compared. The photopic contrast was measured under 150 lx ambient light. The comparison results are shown in Table 1.

  The organic EL light emitting devices of Example 1, Example 4, and Example 5 all had substantially the same bright place contrast and light emission luminance. On the other hand, in the organic EL light emitting device of the comparative example, the bright place contrast and the light emission luminance changed drastically depending on the thickness of the light guide film. From Example 1, Example 4, and Example 5, it was found that in the organic EL light-emitting device of the present invention, the bright place contrast was stably good even if the thickness of the light guide film 104 was changed. For this reason, the organic EL light emitting device of the present invention is easy to manufacture. Furthermore, when a full-color display device is configured, the light guide film 104 can have the same thickness for the R, G, and B elements, so that the application to the full-color display device is easy.

  The organic EL light-emitting device of the present invention can be used for display devices used in televisions, mobile phones, computers, game machines, and other various devices.

It is a figure explaining embodiment and the 1st example of the present invention. It is a figure explaining a part of FIG. 1 in detail. It is a figure for demonstrating operation | movement of the circuit for driving the organic electroluminescent light emitting element which concerns on this invention shown in FIG. It is a schematic diagram for demonstrating the display apparatus of this invention which has arrange | positioned the organic EL light emitting element shown in FIG.2 and FIG.3, and the circuit for driving it in the shape of a matrix as 1 pixel. It is a figure which shows the general view of the display apparatus of this invention shown in FIG. It is a figure which shows a video display apparatus as an example which applied the display apparatus of this invention shown in FIG. It is a figure which shows a portable apparatus as an example which applied the display apparatus of this invention shown in FIG. It is a figure explaining a comparative example. It is a figure explaining the 2nd Example of this invention. It is a figure explaining the 3rd Example of the present invention. It is a figure explaining the conventional organic EL light emitting element.

Explanation of symbols

101, 201, 501 Substrate 102, 202, 508 Light absorption film 103, 203 Second reflective film 104, 204 Light guide film 105, 207, 502 Anode 106, 206, 503 Organic light emitting layer 107, 205 Cathode 108, 210, 506 Drive circuit 109, 209, 505 of organic EL light emitting element Bank 110 Opening 111, 509 Insulating layer 208 First reflective film 211, 507 Flattening layer 212 Black matrix 213 Color filter 1001 Organic EL light emitting element 1002 Circuit 1009 Drive transistor 1010 Data line 1011 Holding capacitor 1012 Switch transistor 1013 Pixel 1014 Selection line 1015 Power supply 1016 Power supply line 1017 Data line drive circuit 1018 Selection line drive circuit 1019 Display device 1020 Display area 1021 Interface Control circuit 1022 connecting portion 1023 housing 1024 housing of the portable device

Claims (5)

An organic EL light emitting device having at least a first reflective film on one side and at least a transparent electrode, a light guide film, and a second reflective film on the other side with an organic light emitting layer interposed therebetween,
The second reflecting film has an opening for emitting light, the area of the opening is smaller than the area of the organic light emitting layer, and the light extraction side of the second reflecting film is light except for the opening. An organic EL light-emitting element that is covered with an absorption film, and that the thickness of the light guide film is 0.5 times or more the coherence distance.   The organic light-emitting element according to claim 1, wherein the light guide film is partitioned between subpixels by a reflective film.   A display device comprising: the organic EL light-emitting element according to claim 1; and a plurality of circuits for driving the organic EL light-emitting element.   A portable device comprising the display device according to claim 3.   An image display device comprising the display device according to claim 3.

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