JP2005310799A - Display panel, electronic apparatus with the same, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display panel capable of enhancing visibility even outdoors which can be easily manufactured. <P>SOLUTION: The display panel has at least black layer 11 having a function to mitigate and flatten an uneven step at a lower part, and a light emitting element disposed on the black layer 11. The reflection rate of the black layer 11 is reduced and visibility is enhanced by absorbing light from the outside. By making the black layer 11 flat, it is possible to improve the uniformity of the film thicknesses of a film to be the light-emitting element and improve the in-plane uniformity of light emission. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display panel and the like. In particular, it is for improving the visibility that is lowered by reflection of light from the outside.

  In recent years, display devices such as liquid crystal display devices (LCDs) and display devices using organic electroluminescent elements (hereinafter referred to as organic EL elements) have various electronic devices such as mobile phones, computers, electronic notebooks, and portable game machines. Used for equipment. For this reason, users not only see the display screen of the apparatus indoors but also have an opportunity to see the screen outdoors.

  In this case, a problem arises when light from the outside enters the display screen. The incident light is reflected and visually recognized on the screen. Usually, light that is much stronger outdoors than the indoor is incident on the screen, reflected, and visually recognized. As a result, the contrast of the display device is reduced, making it difficult to see the display screen.

  Here, the case where an organic EL element is used will be considered below. Since the organic EL element is self-luminous and has good visibility and quick response speed, a display device using the element is a promising device for displaying a moving image. However, it is difficult for current organic EL elements to obtain high luminance while ensuring a long life. For this reason, a decrease in visibility due to the influence of light from the outside is inevitable outdoors.

Therefore, in order to improve contrast, a display device having a structure in which an antireflection film made of a laminated film of TiO ₂ and SiO ₂ or the like is formed on the inner and outer surfaces of a sealing cover of the display device has been proposed (for example, a patent). Reference 1). In addition, a display device having a structure in which a circularly polarizing plate is attached to the cover surface and reflection of light from the outside is suppressed has been proposed (for example, see Patent Document 2). Further, high contrast is realized by absorbing light using a reactive atmosphere or TaO _x (tantalum oxide) layered by CVD as an absorption layer (see, for example, Patent Document 3). In addition, an organic EL element having a structure in which a charge injection layer having light absorption and diffusibility is provided (see, for example, Patent Document 4), a display panel in which a black absorber is formed on the bottom side (see, for example, Patent Document 5), and a black multilayer An organic EL element using a film as an electrode (for example, see Patent Document 6) has also been proposed.
Japanese Patent Laid-Open No. 2001-230072 Japanese Patent Laid-Open No. 8-322138 Japanese Patent No. 2901370 Japanese Patent No. 293229 US Pat. No. 5,986,401 JP 2003-17274 A

  However, in the case of such a conventional display device, for example, an expensive member such as a circularly polarizing plate must be attached to the display device. Therefore, the cost increases. In addition, by attaching a filter such as a circularly polarizing plate, even if the organic EL element emits light, the light is not output to the outside, and the actual luminance is reduced and the visibility is lowered.

  There has also been proposed a display device in which the reflectance is suppressed by a three-layer film of an aluminum reflective film, silicon oxide and an aluminum film, and an aluminum semi-transmissive film. In this case, however, the structure is complicated and difficult to manufacture. Furthermore, when actually used as an anode, it is necessary to form a conductive film having a high work function.

  Therefore, the present invention has been made to solve such problems, and it is possible to improve visibility even outdoors and to obtain a display panel with a simpler manufacturing method. To do.

The display panel according to the present invention includes at least a black layer having a function of relaxing a lower step and a light emitting element provided on the black layer.
In the present invention, a black layer is formed on the substrate by a method such as spin coating. The black layer is intended to reduce reflectance by absorbing light from the outside. By forming the black layer by spin coating, steps due to the lower control element, wiring, etc. can be relaxed. For this reason, for example, even when an organic light emitting element is formed on this black layer as in an organic EL display panel, it is possible to improve the uniformity of the thickness of the light emitting layer and to improve the in-plane uniformity of light emission. Can be improved.

The display panel according to the present invention includes at least a conductive black layer formed on a substrate and a light emitting element that is formed on the black layer and emits light based on supplied charges. .
In the present invention, for example, a conductive black layer formed by adding a black dye or carbon black or the like to a conductive resin is formed in accordance with the position of each pixel. . Therefore, in addition to the effect of absorbing light from the outside, the black layer can also be used as an electrode for supplying charges, so that it is not necessary to form another electrode.

In the display panel according to the present invention, the black layer is formed of an allotrope of carbon.
In the present invention, the black layer is formed of an allotrope of carbon such as graphite, diamond-like carbon, amorphous carbon or the like. Therefore, in addition to the effect of absorbing light from the outside, the black layer can also be used as an electrode for supplying electric charges, so that it is not necessary to form another electrode. Furthermore, since high conductivity is obtained in the black layer, it is possible to suppress deterioration in characteristics of the light-emitting element.

In the display panel according to the present invention, a control element for controlling charge supply to the light emitting element is formed on the substrate, and a Peltier element is formed in a portion other than the display portion on the substrate.
In the present invention, the Peltier element and the control element are formed using a common process in order to release the heat generated by the absorbed light from the panel. It is also possible to use a polycrystalline, microcrystalline or amorphous silicon layer, which becomes the active region of the control element, as part of the Peltier element. Therefore, for example, in the case of a display device using organic EL, the temperature rise of the organic EL element can be prevented and the actual light emission lifetime can be improved. Further, by integrally forming the Peltier element on the substrate, the cost can be reduced and the overall size can be reduced.

In addition, an electronic apparatus according to the present invention includes the display panel described above and performs a display function.
In the present invention, the display panel of the present invention is used for a display portion of an electronic device such as a mobile phone or a digital camera. Thereby, reflection of the light from the outside can be suppressed and visibility can be improved. Therefore, it is particularly effective when used outdoors.

Further, the method of manufacturing a display panel according to the present invention includes a step of forming a control element for controlling display for each pixel on a surface opposite to the display surface of the substrate, and a black pigment on the surface side on which the control element is formed. At least a step of forming a black film by applying a photosensitive resin, and a step of forming a through hole or a groove for supplying a charge in the black film in accordance with the position of the pixel.
In the present invention, a control element is formed on silicon deposited on a substrate, a photosensitive resin containing a black pigment is applied to the surface by, for example, spin coating, etc., to form a black film, and a through hole is formed in the film. The groove is formed based on the pixel position. Accordingly, the black layer absorbs light from the outside to reduce the reflected light and reduce the reflectance. Further, by forming the black layer by spin coating, the step due to the lower control element, wiring, etc. can be reduced. For this reason, even when an organic light emitting element is formed on this black layer as in an organic EL display panel, for example, the uniformity of the thickness of the light emitting layer can be improved and the uniformity of light emission can be improved. . Further, the electrode for controlling the electrification supply by the control element and the light emitting element can be directly connected by the through hole or the groove.

Further, the method for manufacturing a display panel according to the present invention includes a step of forming a control element for performing display control for each pixel on a surface opposite to the display surface of the substrate, and a surface side on which the control element is formed. And at least a step of forming a conductive black layer in accordance with the position of each pixel.
In the present invention, for example, a conductive black layer formed by adding a black dye or carbon black or the like to a conductive resin is formed in accordance with the position of each pixel. . Therefore, in addition to the effect of absorbing light from the outside, the black layer can also be used as an electrode for supplying charges, so that it is not necessary to form another electrode.

In the display panel manufacturing method according to the present invention, the active region of the control element is formed of silicon, and when the control element is formed, the Peltier element is also formed in a portion other than the display portion on the substrate. Like that.
In the present invention, the Peltier element and the control element are formed using a common process in order to release the heat generated by the absorbed external light from the panel. It is also possible to use a polycrystalline, microcrystalline or amorphous silicon layer, which becomes the active region of the control element, as part of the Peltier element. Therefore, for example, in the case of a display device using organic EL, the temperature rise of the organic EL element can be prevented and the actual light emission lifetime can be improved.

In the method for manufacturing a display panel according to the present invention, the step of stratifying the black layer is to form a black layer of graphite by a method by vacuum deposition or sputtering.
In the present invention, a black layer of graphite is formed by a method by vacuum deposition or sputtering. Therefore, in addition to the effect of absorbing light from the outside, the black layer can also be used as an electrode for supplying electric charges, so that it is not necessary to form another electrode. Furthermore, since high conductivity is obtained in the black layer, it is possible to suppress deterioration in characteristics of the light-emitting element.

In the method for manufacturing a display panel according to the present invention, the step of forming a black layer is a method of forming a black layer of diamond-like carbon by a method by chemical vapor deposition.
In the present invention, a black layer of diamond-like carbon is formed by a chemical vapor deposition method. Therefore, in addition to the effect of absorbing light from the outside, the black layer can also be used as an electrode for supplying electric charges, so that it is not necessary to form another electrode. Furthermore, since high conductivity is obtained in the black layer, it is possible to suppress deterioration in characteristics of the light-emitting element. Diamond-like carbon is hard and not easily damaged when handled. Therefore, reliability is improved and yield is improved.

In addition, the method for manufacturing a display panel according to the present invention includes a step of forming a light emitting element in accordance with a pixel position after forming a black layer, and a charge having a polarity opposite to the charge supplied from the black layer side. The method includes a step of forming a conductive film for supplying light to the light emitting element on the light emitting element and a step of sealing with a sealing member.
In the present invention, a light emitting element such as an organic EL, a conductive film, and a sealing member are formed on the black layer. Therefore, since the sealing member can be bonded with good adhesion by the unevenness absorption function of the black layer, the reliability is high, the reflection is effectively suppressed, and the visibility of the display screen can be enhanced even outdoors.

In the method for manufacturing a display panel according to the present invention, the step of forming the light emitting element includes the step of forming the partition so that the polymer solution that becomes the light emitting element is accumulated at the pixel position, and then discharging the liquid droplets. It is formed by discharging and fixing to a position to be a pixel by a method.
In the present invention, when a light emitting element is formed using a droplet discharge method (ink jet method), a light emitting element is formed after a partition wall is formed so that a solution is accumulated at a position to be a pixel. A polymer compound solution is discharged and fixed to form a light emitting element. Therefore, a light emitting element can be easily formed without waste by a droplet discharge method. This partition is also effective when the light emitting element is formed by a method such as vacuum deposition.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view for illustrating the configuration of the display panel according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a substrate. In the present embodiment, the substrate 1 is provided with a thin film transistor (hereinafter referred to as TFT (Thin Film Transistor)) serving as a control element (drive element) (FIG. 1 shows only a second TFT 30 described later). .

  FIG. 2 is a plan view showing one pixel constituting the display panel. FIG. 2 mainly shows an element provided between the second low reflection layer 4 (first low reflection layer 3) and the substrate. The first TFT 20 is supplied with a scanning signal via a scanning line gate at its gate electrode. The storage capacitor cap is configured to hold an image signal supplied from the data line sig via the first TFT 20. In the second TFT 30, the image signal held by the holding capacitor cap is supplied to the gate electrode 31.

  The first TFT 20 and the second TFT 30 are formed in an island-shaped semiconductor film. In the first TFT 20, the gate electrode 21 is configured as a part of the scanning line gate, and a scanning signal is supplied. The data line sig is electrically connected to one of the source / drain regions of the first TFT 20 through the through hole of the interlayer insulating film 51, and the drain electrode 22 is electrically connected to the other. The drain electrode 22 is electrically connected to the gate electrode 31 of the second TFT 30 through the through hole of the interlayer insulating film 51. The second TFT 30 is electrically connected to the electrode 2 formed simultaneously with the data line sig through the through hole of the interlayer insulating film 51 in one of the source / drain regions. The electrode 2 is further electrically connected to the first low reflection layer 3, the second low reflection layer 4, and the EL layer 5 through the through hole of the planarization insulating film 52.

  The second TFT 30 is electrically connected to the other of the source / drain regions via a through hole in the interlayer insulating film 51 through a common feed line com. The extended portion 39 of the common power supply line com is opposed to the extended portion 36 of the gate electrode 31 of the second TFT 30 with the interlayer insulating film 51 interposed therebetween as a dielectric film, thereby forming a storage capacitor cap. . Note that the storage capacitor cap may be formed between the scanning line gate and the capacitance line formed in parallel with the above structure formed between the common feeding line com. Further, the storage capacitor cap may be configured using the drain region of the first TFT 20 and the gate electrode 31 of the second TFT 30. Here, TFTs (first TFT 20 and second TFT 30) are used as elements for controlling light emission of each pixel, but the present invention is not limited to this, and other control elements may be used. In this embodiment, alkali glass is used as the substrate 1.

  Reference numeral 2 denotes an electrode for injecting (supplying) holes or electrons (charges) into the EL layer 5. The electrode 2 is made of a metal such as aluminum (Al) or magnesium (Mg). However, the present invention is not limited to this. For example, transparent ITO (Indium Tin Oxide), which is an indium oxide film doped with tin oxide as an impurity, may be used. Instead of ITO, for example, IZO (indium zinc oxide), GZO (gallium zinc oxide), or ICO (InCeO: indium cerium oxide) may be used. In this embodiment, the electrode 2 side is an anode, and the conductive film 6 side described later is a cathode.

Reference numeral 3 denotes a first low reflection layer. In the present embodiment, pure titanium (hereinafter referred to as Ti) is used as the material of the first low reflection layer 3. However, titanium nitride (TiN) or an alloy of titanium and tungsten (TiW) may be used. A layer of titanium oxide (TiO _{x, including} Ti ₂ O ₃ and Ti ₂ O ₅ ) may be used between the first low reflection layer and the second low reflection layer. This is because the reflectance in a specific wavelength region can be reduced by the color inherent to each TiOx. In the present embodiment, the above-described ITO (or IZO, GZO, ICO) is used as the second low reflection layer 4. In the present embodiment, the first low reflection layer 3 and the second low reflection layer 4 also actually serve as electrodes of the light emitting element. Further, Ti which is the first low reflection layer 3 can be used as the electrode 2.

  Reference numeral 5 denotes an EL layer constituting an organic EL element (light emitting element). In this embodiment, the EL layer 5 includes a hole injection (transport) layer 5A made of, for example, a thiophene-based conductive polymer and a light emitting layer 5B made of a light emitting polymer (LEP). In addition, the structure of the EL layer 5 is different from the structure in which the hole (electron) injection layer and the transport layer are distinguished from each other, the structure composed of the electron injection layer, the hole (hole) injection layer, and the light emitting layer. A structure in which the EL layer 5 is formed in a configuration may be used. The second low reflection layer 4 such as ITO may also serve as a hole injection layer, and the thiophene conductive polymer may have a function of a hole transport layer. Reference numeral 6 denotes a conductive film serving as the other electrode for injecting (supplying) holes or electrons into the EL layer 5. In the present embodiment, ITO (or IZO, GZO, ICO) transparent in the visible light region is used as the conductive film 6 in the same manner as the second low reflection layer 4. Here, since ITO has a relatively high work function value, in such a case, for example, BCP (Bassock Proin) with cesium (Cs) added to the interface layer of the electron injection layer of the EL layer 5 A material in which magnesium (Mg) and silver (Ag) are deposited is used so that electrons are easily injected. Further, the light emission control (charge supply control) of the EL layer 5 of each pixel of the display panel corresponds to the EL layer 5 of each pixel by TFTs (first TFT 20 and second TFT 30) provided in each pixel. Therefore, the conductive film 6 does not need to be provided separately for the EL layer 5 of each pixel. Further, the ICO easily injects electrons on the work function, and has a lower sheet resistance than the ITO, so that the entire display panel can be supplied with a low voltage.

  Reference numeral 7 denotes a bank which is used as a so-called dam (partition) for storing a solution in a region where the EL layer 5 is formed when the EL layer 5 of a polymer organic compound is formed by a droplet discharge method used for an ink jet printer or the like. is there. The bank 7 is made of a photosensitive organic material that can be patterned by a photolithography method, such as polyimide or acrylic. Reference numeral 8 denotes a sealing film serving as a sealing member. The sealing film 8 is made of, for example, silicon nitride (SiN), ITO, or the like. When the organic EL element is exposed to moisture, oxygen, or the like, the light emission lifetime is shortened. Therefore, the sealing film 8 is provided in order to prevent moisture, oxygen, and the like from entering the EL layer 5.

  In the display panel of the present embodiment, two layers of the first low reflection layer 3 and the second low reflection layer 4 are used in the anode portion, which is a lower layer than the EL layer 5, and each layer and its interface are mutually connected. Low reflection due to action. Thereby, in addition to simple structure and manufacture, reflection of light from the outside can be suppressed, and a display panel with improved visibility even outdoors can be obtained.

  Next, a method for manufacturing the display panel of the present embodiment will be described. First, a semiconductor film made of amorphous silicon having a thickness of about 30 to 70 nm is formed on the substrate 1 by, for example, plasma CVD. Next, the semiconductor film made of an amorphous silicon film is subjected to a crystallization process such as solid phase crystal growth and laser annealing to form a polycrystalline silicon film. Next, the semiconductor film is patterned into an island shape, and a gate insulating film 37 made of a silicon oxide film or silicon nitride film having a thickness of about 60 to 150 nm is formed on the surface thereof.

  Next, a conductive film made of a metal film such as titanium (Ti) or tungsten (W) is formed by sputtering and then patterned to form the gate electrodes 21 and 31 and the extended portion 36 of the gate electrode 31. A scanning line gate is also formed.

  In this state, high concentration phosphorous ions are doped to form source / drain regions in a self-aligned manner with respect to the gate electrode. Next, after forming the interlayer insulating film 51, each through hole is formed, and the data line sig, the drain electrode 22, the common power supply line com, the extended portion 39 of the common power supply line com, and the electrode 2 (here, a part) are formed. Form. As a result, the first TFT 20, the second TFT 30, and the storage capacitor cap are formed. Although not particularly shown here, other circuits such as a drive circuit may be formed at the same time in a portion other than the display portion.

  Then, before the first low reflection layer 3 and the like are formed, the planarization insulating film 52 is formed in order to reduce the influence of the step caused by the control element formation. Here, the planarization insulating film 52 is formed by, for example, applying polyimide or acrylic by spin coating. Then, a through hole is formed in a portion corresponding to the connection portion between the electrode 2 and the second TFT 30 of the planarization interlayer insulating film 52. Next, after forming a conductive film to be the electrode 2 on the entire surface, patterning is performed to connect the first low reflection layer 3 and the source / drain regions of the second TFT 30. Here, the planarization insulating film 52 is formed by a spin coating method. However, for example, after a silicon oxide film, a silicon nitride film, or the like is formed by a CVD method, an acrylic film, a resist, or the like is formed by a spin coating method and etched. You may make it flat by giving a back | bag.

  FIG. 3 is a diagram showing the relationship between the thickness of titanium, which is the first low reflection layer 3, the pressure during sputtering, and the reflectance. FIG. 3 shows the reflectance at an incident / exit angle of 20 °. FIG. 4 is a diagram showing the relationship between the film thickness of Ti, which is the first low reflection layer 3, the pressure during sputtering, and the maximum reflectance. Here, the maximum reflectance is the maximum value of the reflectance in the visible light region (400 to 700 nm). In general, when the maximum reflectance is low, it can be considered that reflection is low in the entire visible light region. According to FIGS. 3 and 4, the reflectivity also depends on the thickness of Ti (first low reflection layer 3) and the pressure during sputtering.

  When the control element and the electrode 2 are formed on the substrate 1, a thin Ti layer to be the first low reflection layer 3 is then formed by a direct current magnetron sputtering method. In this embodiment, for example, the film was formed in an argon atmosphere at a pressure of 0.3 Pa and a power of 500 W. In this embodiment, a DC magnetron sputtering method is used, but the method is not limited to the sputtering method, and an ion beam evaporation method or the like may be used. Here, the thickness of the first low reflection layer 3 is formed in the range of 30 nm to 400 nm. When the film thickness is 30 nm or less, the reflectance is high, and when it is 400 nm or more, internal stress is likely to occur, which may cause the substrate to warp or peel off the film, or may destroy the element. Moreover, processing becomes difficult.

  FIG. 5 is a diagram showing the relationship between the layer thickness of the second low reflective layer 4 and the reflectance. FIG. 5 describes the case where the thickness of the second low reflective layer 4 is 116 nm and 78 nm. In the same manner as the first low reflection layer 3, a thin ITO layer to be the second low reflection layer 4 is formed by a direct current magnetron sputtering method. In the present embodiment, the sputtering pressure is 0.3 Pa and the power is 100 W. Further, the flow rate ratio of argon gas and oxygen gas was 100: 1, and sputtering was performed with a 4-inch target. Here, the wavelength dependence of the reflectance changes as the layer thickness changes as shown in FIG. When the thickness of the second low reflection layer 4 is 60 to 100 nm, a low reflectance is obtained in the entire wavelength region. In particular, when the thickness is 80 nm or less, the reflectance of light having a wavelength of 450 to 500 nm, which is greatly affected by light incident from the outside, is reduced.

  Here, the surface of the second low reflection layer 4 is not smoothed by sputtering and crystallizing at a high temperature. The surface of the second low reflection layer 4 is layered such that the arithmetic average roughness Ra is 4 to 11 nm as measured by, for example, a stylus type step difference measuring device. Further, the arithmetic average roughness Ra including the substrate 1 and the second low reflection layer 4 is set to 10 to 100 nm. As a result, the reflectance can be further reduced. In order to leave the first low reflection layer 3 and the second low reflection layer 4 only at desired locations, a photosensitive resin is applied and a pattern is formed by photolithography. Then, the second low reflection layer 4 (ITO) is etched with aqua regia using this photosensitive resin as a mask. Further, the first low reflection layer 3 (Ti) is etched with a buffered hydrofluoric acid solution (BHF) having a ratio of hydrofluoric acid to ammonium fluoride of 1: 6. Here, the first low reflection layer 3 and the second low reflection layer 4 are left in a region wider than the region where the EL layers 5 are formed. That is, it extends to the lower region where the bank 7 is formed, and the interval (gap) between the first low reflection layer 3 and the second low reflection layer 4 is made as narrow as possible. Thereby, the fall of the visibility resulting from the reflection from the layer from a board | substrate and a substrate back surface can be suppressed rather than a 1st low reflection layer. Currently, when patterning is performed by photolithography, the minimum value of the gap is substantially the same as the thickness of the layer to be processed. For example, the first low reflection layer 3 and the second low reflection layer 4 are 2 If the total thickness of the layers is 0.1 μm, the minimum gap is approximately 0.1 μm. Here, about the layering process of the 1st low reflection layer 3 and the 2nd low reflection layer 4, you may make it laminate only in a desired location by mask vapor deposition, for example. Mask vapor deposition is a method of forming a pattern by performing vacuum vapor deposition in a state in which a mask made of, for example, stainless steel having a thickness of about 40 to 100 μm having an opening at a desired location is in close contact with a substrate. Further, chromium (Cr: work function 4.5 eV) may be further formed on the second low reflection layer 4.

  Next, a film made of an inorganic material is formed on the surface of the planarization insulating film 52 by PECVD or the like, and patterning is performed so as to leave the region where the bank 7 is formed and the peripheral portion of the second low reflection layer 4. A protective film 61 is formed. For example, when the light emitting layer 5 is formed to a thickness of 0.05 μm to 0.2 μm, the insulating protective film 61 is formed to a thickness of about 0.2 μm to 1.0 μm.

  Then, the organic material bank 7 is formed along the scanning line gate and the data line sig. The bank 7 is a portion that serves as a weir to prevent a liquid containing an organic compound as a material from overflowing next when forming a film by a droplet discharge method. If it is formed with a thickness of 0.2 μm, it is formed with a height of about 1 μm to 2 μm. The bank can be formed by any other method such as a photolithography method or a printing method.

  A solution containing a polymer organic compound is ejected to the region partitioned by the bank 7 by a droplet ejection (inkjet) method, and the EL layer 5 (the hole injection transport layer 5A and the light emitting layer 5B) is formed. The EL layer 5 repeats filling and drying of a liquid containing an organic compound material for each layer. As a specific example of the light emitting layer 5B, as a red light emitting layer material, the above PPV precursor in an ink is doped with a dye such as rhodamine or berylene, or a PPV precursor (MHE-PPV) is in an ink. Is used. As a material for the blue light emitting layer, a material obtained by dissolving a polyfluorene derivative in an aromatic solvent such as xylene to form an ink is used. Next, in the case of a PPV precursor solution (in which the PPV precursor solution is diluted with DMF to form an ink), the solvent is removed under reduced pressure, and it is conjugated and fixed by a heat treatment at 150 degrees Celsius. Or regarding the material which can be used in common with each pixel, you may laminate | stack each layer of EL layer 5 using a spin coat method, a dip method, etc. FIG. In the case where the organic EL element of the EL layer 5 is composed of a low molecular organic compound, by leaving the region where the EL layer 5 is formed and masking other regions, the organic compound of each layer is deposited. You may stratify. In addition, in order to improve the electron injection efficiency from the conductive film 6, for example, an electron injection layer made of magnesium / silver (Mg / Ag) may be formed by vapor deposition or the like. When the EL layer 5 is formed, an ITO conductive film 6 is formed on the entire surface of at least the display portion by vapor deposition.

  Here, when the first low reflection layer 3 is titanium (including titanium oxide), in order to reduce the reflectance, each of the hole injection transport layer 5A, the light emitting layer 5B (LEP), and the conductive film 6 (ITO). The thickness combinations are preferably stratified as shown in Table 1 below.

  Then, a sealing film 8 made of a transparent resin or a thin layer is formed on the conductive film 6 over the entire device. This protects the EL layer 5 (organic EL element) whose properties change when exposed to moisture, air, etc., and whose light emission lifetime is shortened. As the sealing film 8, for example, SiON (silicon nitride oxide) or MgO (magnesium oxide) is formed using a vapor deposition method so as to transmit visible light, and then a polymer film such as polyvinyl fluoride is used. Are bonded with an adhesive or fused with heat. Further, the display portion can be covered with a transparent substrate as will be described later.

  FIG. 6 is a diagram showing the relationship between the reflectance for each wavelength and the light incident / exit angle when the first low reflection layer 3 and the second low reflection layer 4 are formed. FIG. 6A shows 78 nm ITO obtained by sputtering titanium to be the first low reflection layer 3 and sputtering the second low reflection layer 4 at room temperature. FIG. 6B shows the result of sputtering in the same condition at 280 ° C. for 1 hour after sputtering under the same conditions. FIG. 6C shows the case where only pure titanium as the first low reflection layer 3 is sputtered. FIG. 6D shows a structure composed of three layers of Al, ITO, and Al. Here, with respect to FIG. 6D, the conditions such as the ITO layer thickness are the same as in FIG. 6A. For this reason, the reflectivity may not be the maximum effect, but is shown for reference.

  FIG. 7 is a diagram showing the relationship between the reflectance and the light incident / exit angle for each wavelength when the first low reflection layer 3 is formed of Ti and the second low reflection layer 4 is formed of ICO. FIG. 7A shows an ICO layer that is the second low reflection layer 4 formed at 38 nm. FIG. 7B shows an ICO layer that is the second low reflection layer 4 formed at 76 nm. ICO is formed by sputtering using indium cerium oxide containing 20 at% of cerium oxide (ratio (ratio) of the number of atoms (molecules)) as a target. Although there is a difference in the layer that can reduce the reflectance and the light incident / exit angle depending on the thickness, it can be seen that in both cases, the reflectance near 500 nm with high visibility is reduced. Moreover, according to FIG. 6, FIG. 7, when the 1st low reflection layer 3 is comprised with Ti, it turns out that there exists a tendency for a reflectance to be low.

  As described above, according to the first embodiment, the reflectance is effectively reduced by the interaction between the first low reflection layer 3, the second low reflection layer 4, the EL layer 5, and their interfaces. I can do it. Therefore, the visibility of the screen displayed on the display panel can be improved even outdoors. This is particularly self-luminous and is effective for a display panel (display device) using an organic EL element. In addition, since Ti, TiN or TiW is used as the first low reflection layer 3 and an ITO film is used as the second low reflection layer 4, reflection suppression can be effectively exhibited. In addition, the basic structure of low reflection is composed of two layers of the first low reflection layer 3 and the second low reflection layer 4 and is easy to manufacture.

Embodiment 2. FIG.
FIG. 8 is a partial cross-sectional view for illustrating the configuration of the display panel according to the second embodiment of the present invention. In FIG. 8, the same reference numerals as those in FIG. 1 correspond to those described in the first embodiment, and thus description thereof is omitted. Although FIG. 8 is simplified and it has comprised about the part required for description of this Embodiment, it is not fundamentally different from the structure of FIG. Reference numeral 11 denotes a black layer formed by solidifying an insulating photosensitive resin containing a black pigment (can also serve as the above-described planarization insulating film 52). 5A is a hole injecting and transporting layer, and 5B is a light emitting layer, which is a part of the EL layer 5. In addition, ITO used as the second low reflection layer 4 can also be used as the hole injection transport layer 5A.

  In the present embodiment, the black layer 11 suppresses the light reflected by absorbing light from the outside, and reduces the reflectance. Here, in this embodiment, since the black layer 11 is formed by spin coating, the influence of a step due to a drive element, wiring, or the like can be reduced.

Next, a method for manufacturing the display panel of the present embodiment will be described. Since the steps until the TFT 30 and the electrode 2 are formed on the substrate 1 are the same as those described in the first embodiment, the description thereof is omitted. The substrate is rotated at a predetermined rotation speed, an insulating photosensitive resin in which a black pigment is dispersed is dropped thereon, and the substrate is further rotated at a predetermined rotation speed for a predetermined time to perform spin coating. As the photosensitive resin, for example, COLOR MOSAIC CK CK-A029 (trade name) manufactured by Fuji Film Arch Co., Ltd. was used. This photosensitive resin is a material having an OD value of 3 (value represented by -log (reflectance or transmittance)) at a thickness of 1 μm. The number of revolutions, time, and amount of resin are adjusted so that the layer thickness is about 1 μm (for example, the number of revolutions after dropping is 1000 rpm, the time is 30 seconds, and the amount of resin dripping is 4 ml on a 4-inch substrate). . Thereafter, pre-baking is performed at 110 ° C. for 120 s. And after exposing with the pattern of the electrode 2 (hole injection layer 5A) (for example, irradiating ultraviolet rays of 400 mJ / cm ₂ ), a 20% solution (26 ° C.) of developer CD (trade name) manufactured by Fuji Film Arch Co., Ltd. For 45 seconds, develop, wash with water and dry (220 ° C., 60 minutes). FIG. 9 is an enlarged view of the black layer 11 patterned on the substrate 1 100 times. Here, the grooves are formed. However, in order to achieve the most effect, patterning may be performed so that through holes are formed in accordance with the positions of the respective pixels. By performing such patterning, a contact point between the hole injection transport layer 5A and the electrode 2 is secured.

  When the EL layer 5 is formed using a high molecular organic compound, a solution containing the high molecular organic compound that becomes the hole injecting and transporting layer 5A after forming the bank 7 as in the first embodiment. Are discharged by a droplet discharge method and solidified to form the hole injection transport layer 5A. Further, the EL layer 5 is formed by discharging and solidifying a solution containing a polymer organic compound to be the light emitting layer 5B by a droplet discharge method.

  FIG. 10 is a diagram showing the relationship between the reflectance of the black layer 11 and the light incident / exit angle. The method for forming the conductive film 6 and the sealing film 8 after forming the EL layer 5 is the same as in the first embodiment. In the black layer 11 of the display panel formed by such a method, as shown in FIG. 10, the wavelength dependence is hardly seen in the reflectance in the visible light region.

  As described above, according to the second embodiment, the black layer 11 absorbs light from the outside, thereby reducing the amount of reflected light and reducing the reflectance. Further, since the black layer 11 is formed by spin coating, it is possible to reduce the influence of the step acid due to the driving element, wiring, etc., and to improve the uniformity of the film thickness of the EL layer 5, and to improve the in-plane uniformity of light emission. Can be improved.

Embodiment 3 FIG.
FIG. 11 is a partial cross-sectional view for illustrating a configuration of a display panel according to the third embodiment of the present invention. In FIG. 11, the same reference numerals as those in FIG. 8 correspond to those described in the first and second embodiments, and thus description thereof is omitted. 11A is a black layer formed by an allotrope of conductive carbon.

  In the present embodiment, the reflected light is attenuated and the reflectance is reduced by absorbing light from the outside by the black layer 11A as in the second embodiment. At this time, in this embodiment, carbon allotrope is used as a material to form the black layer 11A. By using conductive carbon as the black layer 11A, there is no need to directly connect the electrode 2 and the hole injection transport layer 5A.

  Next, a method for manufacturing the display panel of the present embodiment will be described. Since the steps until the TFT 30 and the electrode 2 are formed on the substrate 1 are the same as those described in the first embodiment, the description thereof is omitted. Next, the black layer 11A is formed using carbon. Here, DLC (Diamond Like Carbon) is used for the black layer 11A. DLC is a general term for a thin carbon layer having high hardness, infrared transparency, and the like similar to diamond synthesized by a gas phase synthesis method using ions. In the case of DLC, for example, the layers are formed by sputtering, CVD, or the like. As a result, a thinner layer can be formed and the influence on the light emitting element can be reduced as compared with the case where spin coating is performed as in the second embodiment.

  FIG. 12 is a diagram showing the relationship between the reflectance of the black layer 11A and the light incident / exit angle. Subsequent formation of the bank 7 and formation of the EL layer 5, the conductive film 6, and the sealing film 8 perform the same operations as those described in the first and second embodiments, and thus description thereof is omitted. However, the black layer 11A may be formed after the bank 7 is formed first.

  In the above description, the black layer 11A is formed by DLC. However, the black layer 11A can be formed by an allotrope of carbon such as amorphous carbon or graphite. In the case of graphite, stratification is performed using vacuum deposition or sputtering. In the case of using the sputtering method, any allotrope may be used as a target as long as carbon atoms can be sputtered.

  As described above, according to the third embodiment, the black layer 11A made of carbon allotrope, which is a conductor, is formed by a method such as sputtering or vacuum vapor deposition. Thus, the influence on the characteristics of the light emitting element can be reduced.

Embodiment 4 FIG.
In the second and third embodiments, external light incident on the black layer 11 or 11A is absorbed in order to suppress reflection. This absorbed light is converted into heat. Therefore, the temperature of the display panel rises, and the light emission lifetime of the organic compound constituting the EL layer 5 is affected by this heat. In order to prevent this, an element having a Peltier effect (hereinafter referred to as a Peltier element) is formed. The Peltier effect is an endothermic / exothermic phenomenon caused by electric current. A Peltier element is an element that cools the device by utilizing the fact that heat absorption and heat generation occur at the junction when a direct current is passed through a combination of different semiconductors such as P-type and N-type. Accurate temperature control can be performed only by controlling the drive current.

  FIG. 13 shows a display panel provided with a Peltier element. The metal electrode 100, the N-type semiconductor layer 103, the P-type semiconductor layer 104, and the heat dissipation electrode 105 constitute a Peltier element. Next, a method for manufacturing a Peltier element will be described. First, for example, a silicon oxide film is formed on the substrate 1 as a protective film (not shown). Then, for example, a metal to be the metal electrode 100 is formed into a film of, for example, 200 nm by sputtering. For example, chromium (Cr) is used as a material for the metal electrode 100. Thereafter, patterning is performed by photolithography to form a metal electrode 100 having a desired shape.

  Further, a silicon oxide film to be the insulating film 101 is formed at a desired location on the metal electrode 100 using a CVD method or the like. Next, a drive element is formed by the same method as in the first embodiment. It is better to manufacture the light emitting element after manufacturing the Peltier element from the influence on the light emitting layer 5 and the like.

  Next, after patterning the insulating film 101 by photolithography, a desired portion is etched to form an N-type semiconductor layer 103 and a P-type semiconductor layer 104. Here, for example, BiTe (bismuth tellurium) doped (added) with Se (selenium) is used for the N-type semiconductor layer 103 as a material. The P-type semiconductor layer 104 is made of, for example, BiTe doped with Sb (antimony). Then, each of these materials is deposited to a thickness of 500 nm by, for example, a sputtering method. Thereafter, for example, aluminum (Al) serving as the heat radiation electrode 105 is deposited with a thickness of 500 nm, patterned by photolithography, and then etched while leaving a desired portion. Thereafter, the N-type semiconductor layer 103, the P-type semiconductor layer 104, and the heat radiation electrode 105 are formed by maintaining 150 ° C. (BiTe firing temperature) for 1 hour, and a Peltier device is manufactured. The N-type semiconductor layer 103 and the P-type semiconductor layer 104 may be formed by doping an N-type impurity and a P-type impurity at a high concentration, respectively, into a semiconductor layer serving as an active region of the driving element. The heat radiation electrode 105 may be manufactured using the same layer as the wiring layer of the drive element.

  As described above, according to the fourth embodiment, since the heat converted by the light absorbed by the black layer 11 or 11A is released to the outside using the Peltier element, the organic EL that is easily influenced by temperature. The light emission lifetime of the element can be extended. In addition, since the Peltier element is formed together with the TFT 30, the arrangement efficiency of the circuit (element) can be improved.

Embodiment 5 FIG.
Although not specifically described in the second and third embodiments, the second low reflection layer 4 as described in the first embodiment is further formed on the black layers 11 and 11A. Above, the EL layer 5 may be laminated.

Embodiment 6 FIG.
FIG. 14 is a diagram showing a sealing method according to the sixth embodiment of the present invention. In the present embodiment, a sealing method used instead of the sealing film 8 of the first embodiment will be described. In FIG. 14A, for example, a transparent substrate 8A having a recess such as a glass substrate is used for sealing, and the frame portion around the display portion (including the display control circuit in some cases) is covered with an adhesive or the like. Adhere and seal the can. In that case, work should be performed in a vacuum to prevent moisture and the like from entering. Moreover, you may make it enclose the desiccant for absorbing the water | moisture content which enters through an adhesive agent etc. Here, when the second low-reflection layer 4 is formed, an ITO layer is also formed on the frame portion, thereby improving the adhesive spread and improving the adhesion due to the rough surface effect. . Thereby, the penetration | invasion of a water | moisture content and oxygen can be prevented more reliably. FIG. 14B is a diagram in which the space between the transparent substrate 8A and the conductive film 6 is filled with the adhesive 12, and then the whole is bonded. The adhesive 12 can prevent the organic EL element from being attacked by moisture.

  As described above, according to the sixth embodiment, instead of the sealing film 8, the transparent substrate 8A having a recess is bonded and sealed, or the recess of the transparent substrate 8A is filled with an adhesive and bonded. Thus, moisture can be prevented from entering, and the light emission lifetime of the EL layer 5 can be extended.

Embodiment 7 FIG.
In the above-described embodiment, the active matrix display panel has been described. However, the present invention is not limited to this and can be applied to a passive matrix display panel.

Embodiment 8 FIG.
In the above-described embodiments, the display panel using the organic EL element has been described. However, the present invention is not limited to this, and for example, a display panel using an inorganic EL element, an LCD, a PDP, or the like. It can also be realized by a display panel using other similar flat display panels. Moreover, although the above-mentioned embodiment demonstrated the display panel of what is called a top emission structure which takes out the emitted light of the light emitting layer 5B from the surface side in which the light emitting element of the board | substrate 1 was formed, this invention is limited to this. Instead, the present invention can also be applied to a so-called bottom emission display panel in which the light emitted from the light emitting layer 5B is extracted from the surface of the substrate 1 opposite to the surface on which the light emitting elements are formed. Furthermore, when the surface from which light is extracted is covered with glass, considering that the reflectance of the glass is 4%, using a coating agent, a multilayer thin film antireflection film is formed, an antireflection film is attached, etc. AR (Anti Reflection) processing may be performed.

Embodiment 9 FIG.
FIG. 15 is a diagram illustrating an electronic apparatus according to a ninth embodiment of the present invention. 15A shows a PDA (Personal Digital Assistant), FIG. 15B shows a mobile phone, and FIG. 15C shows a digital camera. Although not illustrated in this embodiment mode, the display panel of the present invention can be used for an electronic device that has a display function and uses a display panel, such as a computer or a game machine. This is particularly effective for equipment used outdoors.

FIG. 3 is a partial cross-sectional view of the display panel according to the first embodiment. The top view which shows one pixel which comprises a display panel. The figure showing the relationship between the thickness of the titanium which is the 1st low reflection layer 3, the pressure at the time of sputtering, and a reflectance. The figure showing the relationship between the film thickness of Ti which is the 1st low reflection layer 3, the pressure at the time of sputtering, and the maximum reflectance. The figure showing the relationship between the layer thickness of the 2nd low reflective layer 4, and a reflectance. The figure showing the relationship between the reflectance for every wavelength at the time of laminating | stacking the 1st low reflection layer 3 and the 2nd low reflection layer 4, and a light incident / exit angle. The figure showing the relationship between the reflectance for every wavelength at the time of laminating | stacking the 1st low reflection layer 3 by Ti, and the 2nd low reflection layer 4 by ICO, and a light incident / exit angle. Sectional drawing of a part of display panel which concerns on 2nd Embodiment. The figure which patterned the black layer 11. FIG. The figure showing the relationship between the reflectance of the black layer 11, and a light incident / exit angle. Sectional drawing of a part of display panel concerning a 3rd embodiment. The figure showing the relationship between the reflectance of 11 A of black layers, and a light incident / exit angle. The figure showing the display panel which provided the Peltier device. The figure showing the sealing method which concerns on the 6th Embodiment of this invention. FIG. 15 illustrates an electronic device according to a ninth embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate, 2 Electrode, 3 1st low reflection layer, 4 2nd low reflection layer, 5 EL layer, 5A Hole injection transport layer, 5B Light emitting layer, 6 Conductive film, 7 Bank, 8 Sealing film, 8A Transparent substrate 11, 11A Black layer, 12 Adhesive, 20 First TFT, 21 Gate electrode, 22 Drain electrode, 30 Second TFT, 31 Gate electrode, 36 Extension part of gate electrode 31, 37 Gate insulating film, 39 Insulating part of common electrode com, 51 interlayer insulating film, 52 planarizing insulating film, 61 insulating protective film.

Claims (12)

A black layer having a function of relaxing the lower step,
A display panel comprising at least a light emitting element provided on the black layer. A conductive black layer deposited on the substrate;
A display panel comprising at least a light emitting element provided on the black layer.   The display panel according to claim 2, wherein the black layer is formed of an allotrope of carbon.   4. A control element for controlling charge supply to the light emitting element is formed on a substrate, and a Peltier element is formed on a portion other than the display portion on the substrate. The display panel described in 1.   An electronic apparatus comprising the display panel according to claim 1 and having a display function. Forming a control element for display control for each pixel on the substrate;
Applying a photosensitive resin containing a black pigment to the surface of the substrate on which the control element is formed to form a black film;
Forming a through hole or a groove for supplying electric charges in the black film in accordance with the position of the pixel. Forming a control element for display control for each pixel on the substrate;
And a step of forming a conductive black layer on the surface of the substrate on which the control element is formed in accordance with the position of each pixel.   8. The active region of the control element is formed of silicon, and when the control element is formed, the Peltier element is also formed in a portion other than the display portion on the substrate. Display panel manufacturing method.   9. The method of manufacturing a display panel according to claim 8, wherein the step of forming the black layer comprises forming the black layer of graphite by a method by vacuum deposition or sputtering.   9. The method of manufacturing a display panel according to claim 8, wherein the step of forming the black layer comprises forming the black layer of diamond-like carbon by a chemical vapor deposition method. Forming a light emitting element in accordance with the position to be the pixel after forming the black layer;
Forming a conductive film on the light emitting element for supplying a charge having a polarity opposite to the charge supplied from the black layer side to the light emitting element;
The method for manufacturing a display panel according to claim 6, further comprising a step of sealing with a sealing member. The step of forming the light emitting element includes:
After the partition is formed so that the solution of the polymer compound to be the light emitting element is accumulated at the position to be the pixel, the solution is discharged and fixed to the position to be the pixel by a droplet discharge method. The method of manufacturing a display panel according to claim 11, wherein

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