JP2010033986A - Organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display capable of introducing a micro resonance structure even in a constitution that a plurality of light-emitting elements are laminated. <P>SOLUTION: This device has at least one or more pixels. The pixels are constituted of at least two or more subpixels. The subpixels include a structure in which at least a first electrode layer (first electrode 31), a first organic light-emitting layer (first organic light-emitting layer 32), an intermediate electrode layer (second electrode 33a, third electrode 35b), a second organic light-emitting layer (second organic light-emitting layer 34), and a second electrode layer (fourth electrode 41) are laminated. In at least one subpixel in the pixels, a reflectivity on the upper face side of the intermediate electrode layer is different from that on the upper face side of the intermediate electrode layer of other subpixels. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic EL display device used as a display element.

  Conventionally, a multicolor light emitting element having a configuration in which a plurality of light emitting elements are stacked has been proposed (see Patent Document 1). In the multicolor light emitting element disclosed in Patent Document 1, the stacked light emitting elements are divided by a transparent conductive layer so that they can be individually driven. For example, when three light emitting layers are stacked, the first light emitting layer is sandwiched between the first electrode and the second electrode, the second light emitting layer is sandwiched between the second electrode and the third electrode, and the third light emitting layer is disposed. Is sandwiched between the third electrode and the fourth electrode. In addition, three power supplies for individually driving the three light emitting layers are connected, and since the second electrode and the third electrode are common between the upper and lower light emitting layers, the power supplies are connected in series. It has been configured. There is also a proposal for a technique for setting a microresonance structure for an organic light emitting element (see Non-Patent Document 1).

US Pat. No. 5,707,745 Takahiro Nakayama, Satoshi Tsunoda “Elements with Optical Resonator Structure” Applied Physics Society Organic Molecule / Bioelectronics Subcommittee 1993 Third Workshop p135-143

  However, with the conventional technology described above, it is difficult to individually set a microresonance structure for each of the three light emitting layers. This is because the micro-resonance structures of the respective colors interfere with each other and cannot be optimized individually, and it is necessary to design with the greatest common divisor. For this reason, there existed a subject that the chromaticity change by color purity or a viewing angle, and the light extraction efficiency could not be improved sufficiently.

  The present invention has been proposed in view of the above-described problems, and an object thereof is to provide an organic EL display device that can introduce a microresonance structure even in a configuration in which a plurality of light emitting elements are stacked.

  The organic EL display device of the present invention has the following features in order to achieve the above-described object. That is, the organic EL display device of the present invention has at least one or more pixels, and the pixels are composed of at least two or more subpixels. The subpixel includes a structure in which at least a first electrode layer, a first organic light emitting layer, an intermediate electrode layer, a second organic light emitting layer, and a second electrode layer are stacked. In at least one subpixel in the pixel, the reflectance on the upper surface side of the intermediate electrode layer is different from the reflectance on the upper surface side of the intermediate electrode layer of the other subpixel.

  The reflective electrode in the present invention is not limited to the electrode itself made of a reflective material, but a reflective thin film laminated on the lower part of the electrode made of a transparent conductive material such as ITO or IZO. Also good. Further, the transparent electrode in the present invention is not limited to a general transparent electrode such as ITO, but may be a metal thin film of Ag or Al. In addition, the transmittance is changed at the same time by changing the reflectance, but in the following description, it is described as a reflective electrode having a different reflectance.

  In the organic EL display device of the present invention, the reflectance of the intermediate electrode layer is set to a different value for each subpixel. As a result, even when a plurality of light emitting elements are stacked with a microresonance structure design that is the greatest common divisor, chromaticity change due to color purity and viewing angle and light extraction efficiency can be improved in a specific light emitting element. it can. For example, consider a configuration in which two subpixels are formed, each subpixel is formed of a three-layer stacked element, and two different combinations of elements emit light. In such a configuration, by changing only the reflectance of the intermediate electrode, it is possible to improve the chromaticity change and the light extraction efficiency due to the color purity and viewing angle of the two stacked elements of each subpixel.

  Hereinafter, embodiments of the organic EL display device of the present invention will be described with reference to the drawings. In addition, the well-known or well-known technique in the said technical field is applied about the part which is not described in the following description, and the part which is not shown by drawing. The embodiment described below is an embodiment of the invention and is not limited thereto.

  The organic EL display device according to the embodiment of the present invention has at least one or more pixels, and the pixels are composed of at least two or more subpixels (hereinafter referred to as subpixels). The subpixel has a structure in which at least a first electrode layer, a first organic light emitting layer, an intermediate electrode layer, a second organic light emitting layer, and a second electrode layer are stacked. Specifically, the first electrode corresponds to the first electrode layer, the second electrode and / or the third electrode corresponds to the intermediate electrode layer, and the fourth electrode corresponds to the second electrode layer. The first organic light emitting layer corresponds to the first organic light emitting layer, and the second organic light emitting layer corresponds to the second organic light emitting layer.

  In at least one subpixel in the pixel, the reflectance on the upper surface side of the intermediate electrode layer is different from the reflectance on the upper surface side of the intermediate electrode layer of the other subpixels.

  Further, the intermediate electrode layer of any of the sub-pixels constituting the pixel can be a complete reflection electrode. In addition, a perfect reflection electrode is an electrode which does not have transparency and has a reflectance of 80% or more and 99% or less. Non-reflected light is absorbed by the fully reflective electrode.

  The pixel may be composed of two subpixels. In this case, each subpixel includes a first electrode layer, a first organic light emitting layer, a first intermediate electrode layer, a second organic light emitting layer, a second intermediate electrode layer, a third organic light emitting layer, The structure is composed of two electrode layers. Specifically, the first electrode corresponds to the first electrode layer, the second electrode corresponds to the first intermediate electrode layer, the third electrode corresponds to the second intermediate electrode layer, and the fourth electrode This corresponds to the second electrode layer. The first organic light emitting layer corresponds to the first organic light emitting layer, the second organic light emitting layer corresponds to the second organic light emitting layer, and the third organic light emitting layer corresponds to the third organic light emitting layer. The reflectivity of the first intermediate electrode layer is different for each subpixel.

  First, an organic EL display device according to Example 1 of the present invention will be described. FIG. 1 is a diagram schematically showing a cross-sectional structure in one pixel area of an organic EL display device according to Embodiment 1 of the present invention. FIG. 2 is a schematic perspective view showing the organic EL display device according to Embodiment 1 of the present invention. A plurality of pixels 2 having the cross-sectional structure shown in FIG. 1 are arranged in a matrix, and the display region 1 of the organic EL display device shown in FIG. 2 is configured.

  In FIG. 1, a first subpixel P1, a second subpixel P2, and a third subpixel P3, which are three subpixels, are arranged in parallel in one pixel region. In FIG. 1, 10 is an insulating substrate on which a pixel driving circuit including a TFT is formed, 11a, 11b and 11c are first electrodes, 13a, 13b and 13c are second electrodes, 15a, 15b and 15c are third electrodes, Reference numeral 21 denotes a fourth electrode. In FIG. 1, reference numeral 12 denotes a first organic light emitting layer, 14 denotes a second organic light emitting layer, and 16 denotes a third organic light emitting layer. Further, in FIG. 1, 18b, 18c, 19a, 19c, 20a, and 20b are contact holes, 22 is a protective film, and 23 is a power supply means.

  Each subpixel P1, P2, P3 includes three types of organic light emitting layers 12, 14, 16 having different emission colors and electrodes 11a, 11b, 11c, 13a, 13b, 13c, 15a, 15b, 15c, 21 sandwiching them. It is the structure which laminated | stacked. Each organic light emitting layer and a pair of electrodes arranged on the upper and lower sides sandwiching them form one light emitting element, and in this structure, three light emitting elements are stacked. . The three types of emission colors are red (R), green (G), and blue (B), and the order of color stacking is not particularly limited. The organic light emitting layer may be either a single layer type, a two layer type, a three layer type, a four layer type, or a five layer type. The single layer type is composed of only a light emitting layer, the two layer type is composed of a light emitting layer and a hole injection layer, and the three layer type is composed of an electron transport layer, a light emitting layer, and a hole transport layer. The 4-layer type is composed of an electron injection layer, a light-emitting layer, a hole transport layer, and a hole injection layer, and the 5-layer type is an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, and a hole injection layer. Consists of.

  In such a stacked configuration, the electrodes 13a, 13b, 13c, 15a, 15b, and 15c are shared by the stacked upper and lower light emitting elements. Each subpixel is a top emission type, and the second electrode 13a and the third electrodes 15a and 15b have a low light reflectance of 30% or less and 1% or more. On the other hand, the first electrode 11a, the second electrode 13b, and the third electrode 15c are fully reflective electrodes having high light reflectivity with a reflectance of 80% or more and 99% or less. The fourth electrode 21 is translucent. In Example 1, each organic light emitting layer has a three-layer structure, and is composed of an electron transport layer, a light emitting layer, and a hole transport layer.

  Although a detailed description is omitted because it is a known technique, a planarizing film made of resin is formed on the insulating substrate 10 on which switching elements such as TFTs are formed. A first electrode patterned corresponding to the pixel region is formed.

  Next, a method for manufacturing the organic EL display device shown in FIG. 1 will be described.

  Each layer of the first organic light emitting layer 12 is displayed on the insulating substrate 10 formed up to the first electrodes 11a, 11b, and 11c using a semiconductor process, using a known method such as a coating method or a vapor deposition method. The film is formed sequentially over the entire area. At this time, the sub-pixels are not separately painted using a metal mask as in the prior art.

  As a material of each organic material layer constituting the organic light emitting layer, at least one selected from an organic light emitting material, a hole injection material, an electron injection material, a hole transport material, and an electron transport material can be used. You may comprise so that the selection range of color development may be expanded by doping an organic light emitting material in a hole injection material or a hole transport material, or doping an organic light emitting material in an electron injection material or an electron transport material. Furthermore, each organic material layer is preferably an amorphous film from the viewpoint of luminous efficiency. Organic light-emitting materials include triarylamine derivatives, stilbene derivatives, polyarylenes, aromatic condensed polycyclic compounds, aromatic heterocyclic compounds, aromatic heterocondensed ring compounds, metal complex compounds, etc., and single or composite oligos thereof. Can be used. The configuration of the present invention is not limited to these materials. The thickness of the organic light emitting layer is preferably about 0.05 μm to 0.3 μm, and more preferably about 0.05 to 0.15 μm. Moreover, as a hole injection material and a transport material, a phthalocyanine compound, a triarylamine compound, a conductive polymer, a perylene compound, an Eu complex, or the like can be used, but the structure of the present invention is limited to these materials. is not. Examples of the electron injection material and the transport material include Alq3 in which an 8-hydroxyquinoline trimer is coordinated to aluminum, an azomethine zinc complex, a distyrylbiphenyl derivative system, and the like. It is not limited to.

  After forming the first organic light emitting layer 12, contact holes 18 b and 18 c are formed in the first organic light emitting layer 12. As a forming method, laser processing is preferable, and a known method generally used for thin film processing such as YAG laser (including SHG and THG) and excimer laser can be used. A desired position is obtained by irradiating the laser light on the organic light emitting layer 12 in a predetermined pattern by scanning the laser light to a few μm, or by using a planar light source through a mask that passes through the contact hole portion. Contact holes 18b and 18c are formed in the substrate. The diameters of the contact holes 18b and 18c are preferably 2 μm to 15 μm.

  Next, the second electrodes 13a, 13b, and 13c are formed by patterning. At this time, the first electrodes 11b and 11c are connected to the second electrodes 13b and 13c through the contact holes 18b and 18c, respectively. As the electrode material of the second electrode 13a, a material having high transmittance is preferable. For example, a transparent conductive film such as ITO, IZO, ZnO, or an organic conductive film such as polyacetylene is preferably used. Further, a semi-transmissive film in which a metal material such as Ag or Al is formed with a film thickness of about 10 nm to 30 nm may be used. The electrode material of the second electrode 13b is preferably a light-reflective member. For example, it is preferable to use a material having high reflectivity such as Cr, Al, Ag, Au, and Pt. Thus, the reflectance is made different between the second electrode 13a and the second electrode 13b. As a patterning method, the above-described laser processing can be performed after forming an electrode material in the entire display region 1, but it may be selectively formed using a metal mask. Alternatively, the substrate on which the electrode material is formed may be opposed to the insulating substrate 10 and selectively transferred by laser ablation.

  Next, the second organic light emitting layer 14, the contact holes 19a and 19c, the third electrodes 15a, 15b and 15c, the third organic light emitting layer 16 and the contact holes 20a and 20b are sequentially formed by the same method as described above. . The third electrodes 15a and 15b are preferably made of a material having high transmittance, and the third electrode 15c is preferably a light reflective member.

  Next, the fourth electrode 21 is formed by sputtering or the like. As a material of the fourth electrode 21, a material having a high transmittance is preferable. Furthermore, silicon nitride oxide was formed as the protective film 22 to obtain an organic EL display device.

  An equivalent circuit of the organic EL display device thus formed is shown in FIG. FIG. 3 is a diagram showing an equivalent circuit of the organic EL display device according to Embodiment 1 of the present invention.

  As described above, in the first subpixel P1, the second electrode 13a and the third electrode 15a are connected (short-circuited) via the contact hole 19a. The third electrode 15a and the fourth electrode 21 are connected (short-circuited) via the contact hole 20a. As described above, the light emitting element in which the upper and lower electrodes are short-circuited has a configuration in which an effective voltage is not applied to the organic light emitting layer sandwiched therebetween, and thus does not emit light effectively. Hereinafter, a process that does not cause effective light emission to some of the light-emitting elements in the stacked light-emitting elements is referred to as a non-light-emitting process. In Example 1, the short circuit between the upper and lower electrodes is a non-light emitting process. As a result of this non-light emitting process, the first subpixel P1 is configured to apply an effective voltage only to the first organic light emitting layer 12. Similarly, an effective voltage is applied only to the second organic light emitting layer 14 in the second subpixel P2, and an effective voltage is applied only to the third organic light emitting layer 16 in the third subpixel P3. It has become. Here, the “effective voltage” means a voltage applied to obtain a desired light emission luminance, and an unintended voltage generation due to a leak current is excluded.

  As shown in FIG. 3, each subpixel includes switching TFTs 101a, 101b, and 101c, driving TFTs 102a, 102b, and 102c, stacked light emitting elements, and capacitors 103a, 103b, and 103c.

  Here, the gate electrodes of the switching TFTs 101 a, 101 b, and 101 c are connected to the gate signal line 105. The source regions of the switching TFTs 101a, 101b, and 101c are connected to the source signal lines 106a, 106b, and 106c, and the drain regions are connected to the gate electrodes of the driving TFTs 102a, 102b, and 102c. The source regions of the driving TFTs 102a, 102b, and 102c are connected to the power supply line 107, and the drain region is connected to the first electrodes 11a, 11b, and 11c at one end of the light emitting element. Note that the other end of the light emitting element is connected to the fourth electrode 21 (GND connection). The electrodes of the capacitors 103a, 103b, and 103c are connected to the gate electrodes of the driving TFTs 102a, 102b, and 102c and the power supply line 107 (potential 5V). In this manner, the driving TFTs 102a, 102b, and 102c and the light emitting elements are connected in series, and the current flowing through the light emitting elements is determined according to the data signals supplied from the source signal lines 106a, 106b, and 106c. Control is performed by 102b and 102c. Note that this pixel circuit uses a known circuit configuration called a current programming method, and a detailed description of the operation is omitted. Further, in the configuration of the present embodiment, since each of the sub-pixels can be driven independently, simultaneous emission of RGB three colors is possible.

  At this time, the film thicknesses of the first organic light-emitting layer 12, the second organic light-emitting layer 14, and the third organic light-emitting layer 16 are determined according to the emission color, and the optical distance and reflectance with respect to the electrodes sandwiching each organic light-emitting layer. Set based on. Thereby, it is possible to provide an organic EL display device capable of introducing a microresonance structure even in a laminated configuration.

  FIG. 4 is a diagram schematically showing a cross-sectional structure in one pixel (pixel) region of an organic EL display device according to Example 2 of the present invention. A plurality of pixels having the cross-sectional structure shown in FIG. 4 are arranged in a matrix, and the display region 1 of the organic EL display device shown in FIG. 2 is configured. The organic EL display device of Example 2 is a top emission type.

  In FIG. 4, reference numeral 30 denotes an insulating substrate on which a pixel circuit including TFTs is formed as necessary. In FIG. 4, 31 is a first electrode, 33a and 33b are second electrodes, 35a and 35b are third electrodes, 41 is a fourth electrode, 32 is a first organic light emitting layer, 34 is a second organic light emitting layer, Reference numeral 36 denotes a third organic light emitting layer, and 38b and 39a denote contact holes. Further, in FIG. 4, reference numeral 42 denotes a protective film, and 43 denotes power supply means. Each organic light emitting layer of Example 2 has a three-layer structure, and is composed of an electron transport layer, a light emitting layer, and a hole transport layer. Further, the materials of the organic light emitting layer and the electrode, and the film forming method are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  In the organic EL display device according to the second embodiment, one pixel includes a first subpixel P1 and a second subpixel P2. On the insulating substrate 30, a first electrode 31 is formed in the pixel region. The first electrode 31 and the fourth electrode 41 are common electrodes between the subpixels. Further, the first electrode 31 and the fourth electrode 41 are connected. The connection location of the first electrode 31 and the fourth electrode 41 may be either in the display area or outside the display area, and the same voltage is supplied.

  Further, contact holes 38b and 39a are formed by laser processing, the second electrode 33a and the third electrode 35a of the first subpixel P1 are connected (short-circuited), and the first electrode 31 of the second subpixel P2 is connected. And the second electrode 33b are connected (short-circuited). Similar to Example 1 described above, in Example 2, this short circuit is a non-light emitting process.

  As described above, in the second embodiment, it is not necessary to separately coat the first organic light emitting layer 32, the second organic light emitting layer 34, and the third organic light emitting layer 36, and the number of subpixels is two. Therefore, the aperture ratio can be increased.

  FIG. 5 shows a circuit of each pixel of the organic EL display device thus formed. FIG. 5 is a diagram showing an equivalent circuit of the organic EL display device according to Embodiment 2 of the present invention.

  As shown in FIG. 5, each subpixel includes switching TFTs 201a and 201b, driving TFTs 202a and 202b, stacked light emitting elements, and capacitors 203a and 203b. Here, the gate electrodes of the switching TFTs 201 a and 201 b are connected to the gate signal line 205. The source regions of the switching TFTs 201a and 201b are connected to the source signal lines 206a and 206b, and the drain regions are connected to the gate electrodes of the driving TFTs 202a and 202b. The source regions of the driving TFTs 202a and 202b are connected to the power supply line 207, and the drain region is connected to an electrode at one end of the light emitting element. In the first subpixel P1 shown in FIG. 4, the drain region is connected to the third electrode 35a, and the second subpixel P2 is connected to the third electrode 35b in the same manner. The electrode at the other end of the light emitting element is connected to the fourth electrode 41. The electrodes of the capacitors 203a and 203b are connected to the gate electrodes of the driving TFTs 202a and 202b and GND. Thus, the driving TFTs 202a and 202b and the light emitting elements are connected in series, and the current flowing through the light emitting elements is controlled by the driving TFTs 202a and 202b in accordance with the data signals supplied from the source signal lines 206a and 206b. The light emission is controlled by.

  Next, a driving method of the organic EL display device of Example 2 will be described with reference to FIG. FIG. 6 is a diagram illustrating an example of a driving waveform of the organic EL display device.

  As shown in FIG. 6, when the potential of the gate signal line 205 is set to Vg at time t1, the switching TFTs 201a and 201b are turned on. As a result, the potential Vsig1 of the source signal lines 206a and 206b is charged to the gate capacitances of the capacitors 203a and 203b and the driving TFTs 202a and 202b via the switching TFTs 201a and 201b.

  At time t2, the potential of the gate signal line 205 is set to 0V, the switching TFTs 201a and 201b are turned off, and the voltages charged in the capacitors 203a and 203b are held.

  At time t3, the potentials of the first electrode 31 and the fourth electrode 41 are set to Vc. At this time, since the power supply line 207 remains at 0 V, a potential difference is generated between the organic light emitting layer and the source and drain of the driving TFTs 202a and 202b. Thus, electrons are injected from the second electrode 33a and the third electrode 35b into the first organic light emitting layer 32 and the second organic light emitting layer 34, and holes are injected from the first electrode 31 and the second electrode 33b to emit light. can get. This emitted light is emitted from the protective film 42 side. Note that no light is emitted because a reverse voltage is applied to the third organic light emitting layer 36. The current flowing in the organic light emitting layer is controlled by the driving TFTs 202a and 202b, and a current I1 flows between the source and drain of the driving TFTs 202a and 202b in accordance with the voltage charged in the capacitors 203a and 203b. This state is maintained until time t4.

  At time t4, the potentials of the first electrode 31 and the fourth electrode 41 are set to 0V. Then, since there is no potential difference between the organic light emitting layer and the source and drain of the driving TFTs 202a and 202b, the first organic light emitting layer 32 and the second organic light emitting layer 34 do not emit light. Subsequently, a signal Vsig2 for causing the third organic light emitting layer 36 to emit light is set to the source signal lines 206a and 206b.

  At time t5, when the potential of the gate signal line 205 is set to Vg, the switching TFTs 201a and 201b are turned on. As a result, the potential Vsig2 of the source signal lines 206a and 206b is charged to the gate capacitances of the capacitors 203a and 203b and the driving TFTs 202a and 202b via the switching TFTs 201a and 201b.

  At time t6, the potential of the gate signal line 205 is set to 0V, the switching TFTs 201a and 201b are turned off, and the voltages charged in the capacitors 203a and 203b are held.

  At time t7, the potential of the power supply line 207 is set to Vc. At this time, since the potentials of the first electrode 31 and the fourth electrode 41 are 0 V, a potential difference is generated between the organic light emitting layer and the source and drain of the driving TFTs 202a and 202b. As a result, electrons are injected from the fourth electrode 41 into the third organic light emitting layer 36 and holes are injected from the third electrodes 35a and 35b, so that the organic molecules excited by the recombination of electrons and holes are brought into the ground state. Luminescence is obtained when relaxing. This emitted light is emitted from the protective film 42 side. The first organic light emitting layer 32 and the second organic light emitting layer 34 do not emit light because a reverse voltage is applied. The current flowing in the organic light emitting layer is controlled by the driving TFTs 202a and 202b, and a current I2 flows between the source and drain of the driving TFTs 202a and 202b in accordance with the voltage charged in the capacitors 203a and 203b. This state is maintained until time t8.

  At time t8, the potential of the power supply line 207 is set to 0V. Then, since there is no potential difference between the organic light emitting layer and the source and drain of the driving TFTs 202a and 202b, the third organic light emitting layer 36 does not emit light.

  By repeating the above-described operation, the first organic light emitting layer 32, the second organic light emitting layer 34, and the third organic light emitting layer 36 can emit light in a time division manner. Specifically, the power source means 43 is driven with a period that cannot be identified by humans, for example, about 60 Hz or higher, so that the emission colors of the first organic light emitting layer 32 and the second organic light emitting layer 34 and the third Light of any mixed color with the emission color of the organic light emitting layer 36 can be expressed.

  In the second embodiment, the first electrode 31 and the second electrode 33b are reflective electrodes, and the second electrode 33a and the third electrodes 35a and 35b are intermediate electrodes with optimized reflectivity and transmittance, respectively. Is a transparent electrode. In this case, the reflective electrode can be a fully reflective electrode. Further, in the laminated structure, the film thicknesses of the first organic light emitting layer 32, the second organic light emitting layer 34, and the third organic light emitting layer 36 are adjusted based on the optical distance to each reflective electrode in accordance with the emission color. An organic EL display device capable of introducing a microresonance structure can be provided.

  FIG. 7 is a diagram schematically showing a cross-sectional structure in one pixel area of an organic EL display device according to Example 3 of the present invention. A plurality of pixels having the cross-sectional structure shown in FIG. 7 are arranged in a matrix, and the display region 1 of the organic EL display device shown in FIG. 2 is configured. The organic EL display device of Example 2 is a top emission type.

  In FIG. 7, reference numeral 30 denotes an insulating substrate on which a pixel circuit including TFTs is formed as necessary. Reference numeral 31 denotes a first electrode, 33a denotes a second electrode, 35b denotes a third electrode, 41 denotes a fourth electrode, 32 denotes a first organic light emitting layer, 34 denotes a second organic light emitting layer, and 36 denotes a third organic light emitting layer. Show. In FIG. 7, reference numeral 42 denotes a protective film, and 43 denotes power supply means. Each organic light emitting layer of Example 3 has a three-layer structure, and is composed of an electron transport layer / a light emitting layer / a hole transport layer. In addition, since the materials of the organic light emitting layer and the electrode and the film forming method are the same as those in the first embodiment, detailed description thereof is omitted. However, in Example 3, the second electrode 33a and the third electrode 35b are semi-transmissive electrodes and have light reflectivity as well as light transmittance. For example, a thin film made of a material having high reflectance such as Cr, Al, Ag, Au, or Pt is preferable. At this time, the film thickness is set so as to achieve desired reflectance and transmittance. The reflectivity and transmissivity of the second electrode 33a and the third electrode 35b are different depending on each emission color.

  In the organic EL display device described above, one pixel is composed of a first subpixel P1 and a second subpixel P2. On the insulating substrate 30, a first electrode 31 is formed in the pixel region. The first electrode 31 and the fourth electrode 41 are common electrodes between the subpixels. Further, the first electrode 31 and the fourth electrode 41 are connected. The connection location between the first electrode 31 and the fourth electrode 41 may be either in the display area or outside the display area, and the same voltage is supplied.

  Thus, in Example 3, since it is not necessary to coat the third organic light emitting layer 36, the process can be simplified. Further, by coating the first organic light emitting layer 32 and the second organic light emitting layer 34 separately, only two organic layers need be stacked, and the light extraction efficiency can be improved as compared with the case of three layers. Further, since the number of subpixels is two, which is smaller than that of the first embodiment, the aperture ratio can be increased.

  A circuit of each pixel of the organic EL display device thus formed is shown in FIG. FIG. 8 is a diagram showing an equivalent circuit of the organic EL display device according to Example 3 of the present invention.

  As shown in FIG. 8, each subpixel includes switching TFTs 201a and 201b, driving TFTs 202a and 202b, stacked light emitting elements, and capacitors 203a and 203b. Here, the gate electrodes of the switching TFTs 201 a and 201 b are connected to the gate signal line 205. The source regions of the switching TFTs 201a and 201b are connected to the source signal lines 206a and 206b, and the drain regions are connected to the gate electrodes of the driving TFTs 202a and 202b. The source regions of the driving TFTs 202a and 202b are connected to the power supply line 207, and the drain region is connected to an electrode at one end of the light emitting element. In the first subpixel P1 shown in FIG. 7, the drain region is connected to the second electrode 33a, and the second subpixel P2 is also connected to the third electrode 35b. The electrode at the other end of the light emitting element is connected to the fourth electrode 41. The electrodes of the capacitors 203a and 203b are formed so as to be connected to the gate electrodes of the driving TFTs 202a and 202b and GND. Thus, the driving TFTs 202a and 202b and the light emitting elements are connected in series, and the current flowing through the light emitting elements is controlled by the driving TFTs 202a and 202b in accordance with the data signals supplied from the source signal lines 206a and 206b. The light emission is controlled by.

  Since the driving method of the organic EL display device of the third embodiment is the same as that of the second embodiment, the description thereof is omitted.

  In the third embodiment, the first electrode 31 is a reflective electrode, the second electrode 33a and the third electrode 35b are light transmissive and light reflective electrodes, and the fourth electrode 41 is a transparent electrode. In this case, the reflective electrode can be a fully reflective electrode. Further, according to the emission color, the film thicknesses of the first organic light emitting layer 32, the second organic light emitting layer 34, and the third organic light emitting layer 36, and the light transmission and reflection characteristics of the second electrode 33a and the third electrode 35b, Adjust individually based on optical design. Thereby, it is possible to provide an organic EL display device capable of introducing a microresonance structure even in a laminated configuration.

1 is a schematic cross-sectional view showing one pixel of an organic EL display device according to Example 1 of the present invention. 1 is a schematic perspective view showing an organic EL display device according to Example 1 of the present invention. 1 is a diagram showing an equivalent circuit of an organic EL display device according to Example 1 of the present invention. FIG. 5 is a schematic cross-sectional view showing one pixel of an organic EL display device according to Example 2 of the invention. FIG. 6 is a diagram illustrating an equivalent circuit of an organic EL display device according to Example 2 of the invention. The figure which shows an example of the drive waveform of an organic electroluminescence display. FIG. 6 is a schematic cross-sectional view showing one pixel of an organic EL display device according to Example 3 of the invention. FIG. 10 is a diagram illustrating an equivalent circuit of an organic EL display device according to Example 3 of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display area 2 Pixel 10 Insulating substrate 11a, 11b, 11c 1st electrode 12 1st organic light emitting layer 13a, 13b, 13c 2nd electrode 14 2nd organic light emitting layer 15a, 15b, 15c 3rd electrode 16 3rd organic light emission Layer 18b, 18c, 19a, 19c, 20a, 20b Contact hole 21 Fourth electrode 22 Protective film 23 Power supply means 30 Insulating substrate 31 First electrode 32 First organic light emitting layer 33a, 33b Second electrode 34 Second organic light emitting layer 35a, 35b Third electrode 36 Third organic light emitting layer 38b, 39a Contact hole 41 Fourth electrode 42 Protective film 43 Power supply means 101a, 101b, 101c Switching TFT
102a, 102b, 101c Driving TFT
103a, 103b, 103c Capacitor 105 Gate signal line 106a, 106b, 106c Source signal line 107 Power supply line 201a, 201b Switching TFT
202a, 202b Driving TFT
203a, 203b Capacitor 205 Gate signal line 206a, 206b Source signal line 207 Power supply line P1 First subpixel P2 Second subpixel P3 Third subpixel

Claims (3)

The pixel includes at least one pixel, and the pixel includes at least two subpixels. The subpixel includes at least a first electrode layer, a first organic light emitting layer, an intermediate electrode layer, a second An organic EL display device including a structure in which an organic light emitting layer and a second electrode layer are laminated,
The organic EL display device, wherein the reflectance of the upper surface side of the intermediate electrode layer is different from the reflectance of the upper surface side of the intermediate electrode layer of another subpixel in at least one subpixel in the pixel.   The organic EL display device according to claim 1, wherein the intermediate electrode layer of any one of the sub-pixels constituting the pixel is a complete reflection electrode. The pixel is composed of two sub-pixels,
Each subpixel includes a first electrode layer, a first organic light emitting layer, a first intermediate electrode layer, a second organic light emitting layer, a second intermediate electrode layer, a third organic light emitting layer, and a second electrode. Consist of layers,
The organic EL display device according to claim 1, wherein the reflectance of the first intermediate electrode layer is different for each subpixel.

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