JP2008059824A - Active matrix type organic EL panel and manufacturing method thereof - Google Patents

Description

  The present invention relates to an active matrix organic EL panel and a manufacturing method thereof, and more particularly to a color conversion type or color filter type active matrix organic EL panel and a manufacturing method thereof.

  In recent years, the spread of flat displays for information equipment has been remarkable. Among these, a liquid crystal display obtains color using a color filter by controlling on / off of backlight light by an optical shutter function of liquid crystal. On the other hand, in an organic EL display (or organic LED display), each pixel emits light individually (that is, self-emission). For this reason, the organic EL display not only has an advantage of a wide viewing angle but also can be reduced in thickness because it does not require a backlight, and can be formed on a flexible substrate. Have advantages. For this reason, an organic EL display is expected as a next-generation display.

  The driving methods of these display panels can be roughly divided into two types. The first drive method is called a passive matrix type (or duty drive method, simple matrix method). In this method, a plurality of stripe-shaped electrodes are combined in rows and columns in a matrix, and light is emitted by a drive signal applied to the row and column electrodes at each intersection of the row and column electrodes. Signals for light emission control are usually scanned in time series for each row in the row direction, and are simultaneously applied to each column in the same row. Normally, each pixel is not provided with an active element, and is controlled so that light is emitted only during the duty period of each row in the row scanning period.

The second driving method is an active matrix type in which each pixel has a switching element and can emit light over the entire scanning period of a row. For example, assume that the entire panel of 100 rows × 150 columns emits light with a display luminance of 100 Cd / m ² . In this case, since each pixel basically emits light constantly in the active matrix type, each pixel may emit light at 100 Cd / m ² when the area ratio of the pixel and various losses are not taken into consideration. However, when trying to obtain the same display brightness with the passive matrix type, the duty ratio for driving each pixel becomes 1/100, and only the duty period (selection period) becomes the light emission time, so the light emission brightness within the light emission period Needs to be 100 times 10,000 Cd / m ² .

  Here, in order to increase the light emission luminance, the current passed through the light emitting element may be increased. However, for example, in an organic EL light emitting element, it is generally known that the light emission efficiency is lowered while increasing the current. Due to this reduction in efficiency, when the active matrix type driving method and the passive matrix type driving method are compared with the same display luminance, the passive matrix type consumes a relatively large amount of power. Further, when the current passed through the organic EL element is increased, there is a disadvantage that the material is likely to be deteriorated due to heat generation and the life of the display device may be shortened. On the other hand, if the maximum current is limited from the viewpoints of efficiency and lifetime, it is necessary to lengthen the light emission period in order to obtain the same display luminance. However, since the duty ratio that determines the light emission time in the passive matrix driving method is the reciprocal of the number of rows of the panel, the extension of the light emission period leads to the limitation of the display capacity (number of drive lines). From these points, it is preferable to use an active matrix type driving method in order to realize a large-area, high-definition panel. Thus, compared with passive matrix driving, the active matrix driving organic EL panel can be easily increased in area, and the market expected is large. Note that in normal active matrix driving, a method using a thin film transistor as a switching element is known.

  On the other hand, in recent years, the organic EL panel has started to shift its technology from the three-color coating method to the white + color filter method and the color conversion method. This is because the problem of the metal mask used in the three-color painting method is highlighted, and the white + color filter method and the color conversion method that use only the frame mask are beginning to attract attention.

  More specifically, as a method for producing an organic EL panel, a “three-color light emission method” in which organic EL elements that emit red, blue, and green light by applying an electric field are arranged, and a white color emitted by the organic EL element is used. The color filter that emits light with a color filter to express red, blue, and green, and absorbs near-ultraviolet light, blue light, blue-green light, or white light emitted by organic EL elements, and converts the wavelength distribution. A “color conversion method” using a color conversion layer including a color conversion dye that emits light in the visible light region by performing the above-described method has been proposed.

  Among these methods, a color mask layer and / or a color conversion layer having a desired shape and arrangement can be formed by using a photo process without using a metal mask during film formation. The “filter method” and “color conversion method” are considered to be advantageous for increasing the screen size and resolution.

  Therefore, in recent years, active matrix driving organic EL using a white + color filter method or a color conversion method has been actively developed. When an active matrix type organic EL panel is manufactured using a thin film transistor substrate by a color conversion method or a color filter method, a thin film transistor substrate is formed because a color conversion layer or a color filter layer is formed between the thin film transistor substrate and the organic EL layer. And the organic EL layer cannot be connected. More specifically, in the case of such a structure, it is conceivable to form a color conversion layer and a color filter on the TFT substrate, and then planarize with a planarizing layer and provide a passivation layer (SiOx or SiN). The organic EL layer is formed on the passivation layer. Here, in order to transmit a signal from the TFT substrate to the organic EL layer, it is necessary to connect the TFT substrate and the organic EL layer. For this reason, it is necessary to open a contact hole in the passivation layer. On the other hand, the passivation layer has a role to prevent moisture from the color conversion layer, the color filter layer, and the planarization layer from entering the organic EL. For this reason, if a contact hole is formed in the passivation layer, moisture from the planarization layer or the like may enter the organic EL layer side and cause deterioration of the organic EL layer. For this reason, in the above structure, the connection between the TFT substrate and the organic EL is usually impossible.

  For this reason, as shown in FIG. 3, a proposal has been made to realize an active matrix panel by bonding a top emission type organic EL element and a color conversion substrate or a color filter (Non-Patent Document 1, Fuji Time Report, Vol. .77, No. 2, p128-132).

Hiroshi Kimura, “Top emission type CCM organic EL”, Fuji Jiho, Vol.77, No.2, p128-132, (2004) Kenji Nomura, Hiromichi Ohta, Akihiro Takagi, Toshio Kamiya, Masahiro Hirano, Hideo Hosono: Room-Temperature Fabrication of Transparent Flexible Thin Film Transistors Using Amorphous Oxide Semiconductors; Nature, 488, 432, (2004).

  When an active matrix type organic EL panel as shown in FIG. 1 is manufactured, it is necessary to manufacture a top emission element. However, in this case, the top emission element must make the upper electrode a transparent electrode. Therefore, a sputtering method is used to form the upper transparent electrode. However, if an electrode is formed on the organic EL layer by sputtering, the organic EL layer is damaged and the organic EL element does not operate well, or the organic EL element. May be less efficient. In order to solve this, low-damage sputtering such as facing sputtering has been developed. In this case, however, the film formation rate is low and the mass productivity is poor. Furthermore, in order to bond a substrate having a color modulation portion and a top emission substrate, a bonding technique with an accuracy of about 1 μm is required in an inert gas, and a new apparatus for this purpose must be developed. In addition, since there is no place to put a desiccant in the bonding method, there are very many development technical items such as film sealing technology and transparent desiccant.

  On the other hand, according to the three-color coating method, an active matrix type organic EL panel can be manufactured by manufacturing an organic EL element on a thin film transistor substrate, and therefore can be manufactured very easily.

  In view of the above, an object of the present invention is to provide a bottom emission type active matrix organic EL panel of a color filter system or a color conversion system.

According to one aspect of the present invention,
A transparent substrate;
A color modulation section provided on the transparent substrate;
A planarization layer provided on the color modulation unit;
A thin film transistor provided on the planarization layer;
There is provided an active matrix organic EL panel having an organic EL element provided on the thin film transistor so as to be electrically controllable by the thin film transistor.

According to another aspect of the present invention, a method of manufacturing an active matrix organic EL panel,
Providing a transparent substrate;
Providing a color modulator on the transparent substrate;
Providing a planarization layer on the color modulation unit;
Providing a thin film transistor on the planarizing layer;
Providing an organic EL element on the thin film transistor so as to be electrically controllable by the thin film transistor.

  As will be described in detail below, according to the present invention, an active matrix type organic EL panel of a color filter type or a color conversion type, and a bottom emission type is provided. That is, according to the present invention, there is provided a completely new bottom emission type active matrix organic EL element in which an organic EL is directly formed on a thin film transistor in the same manner as the three-color coating method.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

  As described above, according to one aspect of the present invention, the transparent substrate 1, the color modulation units 2R, G, B and 3R, G, the planarization layer 3, the thin film transistors 6 to 10, and the organic EL elements 13 to 15, an active matrix type organic EL panel is provided. FIG. 1 shows a schematic cross-sectional view of an organic EL panel according to the present invention.

  The organic EL panel according to the present invention has a transparent substrate 1. The transparent substrate is preferably transparent to visible light (wavelength 400 to 700 nm). The transparent substrate is preferably one that can withstand the conditions (solvent, temperature, etc.) used to form the layer to be laminated. The transparent substrate is preferably excellent in dimensional stability. Preferred transparent substrates include glass substrates and rigid resin substrates formed of resins such as polyolefins, acrylic resins (including polymethyl methacrylate), polyester resins (including polyethylene terephthalate), polycarbonate resins, or polyimide resins. . Alternatively, a preferred transparent substrate includes a flexible film formed from polyolefin, acrylic resin (including polymethyl methacrylate), polyester resin (including polyethylene terephthalate), polycarbonate resin, polyimide resin, or the like. The thickness of the transparent substrate can be set to 1.1 mm, for example.

  The organic EL panel according to the present invention has color modulation portions 2R, G, B and 3R, G provided on the transparent substrate. In the present specification, “provided on” intends to be provided in the direction in which the organic EL element exists with respect to the transparent substrate. The provision of the color modulation unit on the transparent substrate includes not only the case where the color modulation unit is provided directly on the transparent substrate but also the case where the color modulation unit is provided on the transparent substrate via some member. The same applies to other members.

  The color modulation part can be composed of a color filter layer, a color conversion layer, or a laminate of a color filter layer and a color conversion layer. The color filter layer is a layer that transmits only light in a desired wavelength range. In the case of adopting a laminated structure of a color filter layer and a color conversion layer, the color filter layer is effective for improving the color purity of light subjected to wavelength distribution conversion in the color conversion layer. The color filter layer can be formed using, for example, a commercially available color filter material for liquid crystal (such as a color mosaic manufactured by Fuji Film Electromaterials).

  The color conversion layer is preferably a layer having a color conversion dye and a matrix resin. The color conversion dye is a dye that converts the wavelength distribution of incident light and emits light in different wavelength ranges, and preferably has a wavelength of light from an organic light emitting layer (for example, near ultraviolet light or blue to blue-green light). A pigment that performs distribution conversion and emits light in a desired wavelength band (for example, blue, green, or red). Color conversion dyes are known in the art, such as rhodamine dyes and cyanine dyes that emit red light; coumarin dyes and naphthalimide dyes that emit green light; and coumarin dyes that emit blue light. Any thing that can be used.

  A plurality of types of color modulation units, for example, a red modulation unit that absorbs light from an organic light emitting layer and emits red light, a green modulation unit that emits green light, and a blue modulation unit that emits blue light on one transparent substrate Etc. can be provided. In the present invention, full color display is possible by arranging a plurality of types of color modulation sections in a matrix.

  The thickness of the color modulation part can be set to 10 μm, for example. In addition, the size of the color modulation unit can be set, for example, to a width of 0.08 mm and a pitch of 0.11 mm.

  The color modulation part can be formed by applying the material of each color modulation part using a spin coating method, a roll coating method, a casting method, a dip coating method, or the like, and patterning using a photolithographic method or the like.

  When the organic EL panel according to the present invention includes a plurality of color modulation units, it is preferable that the organic EL panel further includes a light shielding unit provided on the transparent substrate and between the plurality of color modulation units. The light shielding portion can be formed using a commercially available color filter material for liquid crystal (such as a color mosaic manufactured by Fuji Film Electro Materials). The thickness of the light shielding part can be set to 1 μm, for example. The light shielding portion can be formed by applying a material for the light shielding portion using a spin coating method or the like and patterning using a photolithographic method or the like.

  The organic EL panel according to the present invention includes a planarization layer 4 provided on the plurality of color modulation units. By providing the planarization layer, the surface for forming the electrode can be further planarized. As a material for the planarization layer, a known material such as a transparent organic resin can be used. The thickness of the planarization layer can be set to 0.1 to 10 μm, for example, on the color modulation portion. The planarization layer can be formed by any known method. For example, the planarization layer can be formed by applying an organic resin by a spin coating method and patterning by a photolithography method.

  The organic EL panel according to the present invention preferably further includes a passivation layer 5 provided between the planarization layer and the thin film transistor. By providing the passivation layer, oxygen and / or moisture can be blocked. Examples of the material for the passivation layer include insulating inorganic oxides such as SiOx, SiNx, SiNxOy, AlOx, TiOx, TaOx, and ZnOx, inorganic nitrides, and inorganic oxynitrides. The thickness of the passivation layer can be set to 0.1 to 1 μm, for example. The passivation layer can be formed by a known method such as sputtering.

  The organic EL panel according to the present invention further includes thin film transistors 6 to 10 provided on the planarizing layer (preferably on the passivation layer). In a normal bottom emission type organic light emitting device, a color modulation portion, a planarization layer, and a passivation layer are formed on a substrate, and then a transparent electrode such as IZO is formed by sputtering. However, in the present invention, an active matrix element can be obtained by forming a thin film transistor on the substrate between the color modulation portion and the electrode. Further, as will be described in detail below, in the present invention, all steps of forming a thin film transistor can be performed at a temperature of 200 ° C. or lower. Thereby, deterioration of the color modulation unit can be suppressed. Furthermore, according to the present invention, it is possible to form an organic EL panel having the same structure as a conventional color conversion type or white + color filter type passive matrix drive type organic EL panel. For this reason, in the present invention, only the formation process of the thin film transistor portion is increased, and there is no need to greatly change the panel manufacturing process.

  More specifically, the thin film transistor is in electrical contact with the semiconductor layer 8, the gate electrode 6, the gate insulating layer 7 provided between the semiconductor layer and the gate electrode, and the semiconductor layer. It is preferable to have the source electrode 9 and the drain electrode 10 provided separately. Note that the gate electrode, the gate insulating layer, the semiconductor layer, the source electrode, and the drain electrode may be provided in this order on the planarization layer (preferably on the passivation layer), or in the reverse order. You may provide on a planarization layer (preferably on a passivation layer).

  In FIG. 2, the typical front view of the organic electroluminescent panel concerning this invention is shown. Each member included in the thin film transistor (preferably including a semiconductor layer, a gate electrode, a gate insulating layer, a source electrode, and a drain electrode) is not a region 20 (also referred to as a sub-pixel region) corresponding to the color modulation portion. It is preferably provided in a region outside the subpixel region. That is, each member included in the thin film transistor is preferably provided so as not to block light from the organic light emitting element to the color modulation unit. However, as described in detail below, each member included in the TFT (preferably including a semiconductor layer, a gate electrode, a gate insulating layer, a source electrode and a drain electrode) is formed of a transparent material. Thus, the TFT can be arranged at an arbitrary position in the sub-pixel region.

  As described above, the organic EL panel according to the present invention preferably further includes the semiconductor layer 8. As will be described in detail below, the semiconductor layer may include an amorphous oxide semiconductor or an organic semiconductor.

  The semiconductor layer preferably includes an amorphous oxide semiconductor. More specifically, the oxide semiconductor is preferably an In—Zn—Ga—O-based semiconductor. This oxide semiconductor can be transparent. Thereby, there is no light blocked by the TFT, and the light extraction efficiency can be improved. Further, this oxide can be formed at room temperature (Non-Patent Document 2, Kenji Nomura et al.). Therefore, a thin layer transistor using the oxide can be formed without damaging a color modulation portion or the like provided under the thin layer transistor.

  The ratio of In, Zn, Ga, and O can be an atomic ratio of In: Ga: Zn: O = 1.1: 1.1: 0.9: 1.

  The semiconductor layer can be formed by sputtering or laser ablation. More specifically, the semiconductor layer can be formed in oxygen at room temperature (preferably 0 to 100 ° C.) by KrF excimer laser deposition. On the other hand, normal amorphous silicon and LTPS (low temperature polysilicon) cannot be formed at room temperature. Note that Non-Patent Document 1 describes a method for manufacturing a thin film transistor of In—Ga—Zn—O by a laser ablation method at room temperature. In addition, the semiconductor layer can be patterned using photolithography after the formation of the semiconductor film, and patterned as follows using a normal wet etching technique. The etching can be performed at 35 ° C. with 10 wt% oxalic acid, for example.

  In the present invention, in particular, when an inorganic passivation layer is provided on the color modulation portion, a thin film transistor can be formed without the damage of sputtering or laser ablation directly affecting the color modulation portion. Further, as described above, since the In—Zn—Ga—O based semiconductor can be formed at room temperature, a thin film transistor can be formed without causing deterioration of the color modulation portion due to temperature. As described above, according to the present invention, by using an In—Zn—Ga—O based semiconductor, a thin film transistor can be manufactured without damaging the color modulation portion under the thin film transistor.

  The semiconductor layer may include an organic semiconductor. More specifically, pentacene can be used as the organic semiconductor. Organic semiconductors can also be transparent. Thereby, there is no light blocked by the TFT, and the light extraction efficiency can be improved. These organic semiconductors can also be formed at room temperature. For this reason, a thin layer transistor using the organic semiconductor can also be formed without damaging a color modulation portion or the like provided under the thin layer transistor.

  The organic semiconductor layer can be formed, for example, by providing a pentacene layer in an inert gas. Thereafter, as described below, the source and drain electrodes can be formed by depositing Au using, for example, a fine metal mask. Note that in the case where an organic semiconductor layer is provided, the organic semiconductor layer is preferably formed in an inert atmosphere in order to protect organic substances from moisture and oxygen. Further, the semiconductor layer can be patterned using a normal photolithography technique after the semiconductor film is formed.

  Note that whether the amorphous oxide semiconductor is used or the organic semiconductor is used, the thickness of the semiconductor layer can be set to 60 nm, for example.

  The organic EL panel according to the present invention preferably further includes a gate electrode 6. Any metal can be used as the material of the gate electrode, but it is determined in consideration of material cost, ease of thin film formation, adhesion, stability in the atmosphere, and the like. Preferred metals include, but are not limited to, titanium, chromium, cobalt, nickel, copper, aluminum, zirconium, niobium, tantalum, molybdenum and the like. Moreover, ITO and IZO are mentioned as a transparent gate electrode. The thickness of the gate electrode can be set to 80 nm, for example. The formation of the gate electrode can be easily performed by a general method such as vacuum deposition or sputtering. At this time, patterning is performed by a shadow mask or a photo process as necessary. For example, the region where the gate electrode is provided in advance by using a photoresist is limited, and then the photoresist is peeled off, or after forming a thin film, the photoresist is applied, and after exposure and development, unnecessary portions are removed with an appropriate etching solution or the like. Thus, patterning can be performed.

The organic EL panel according to the present invention preferably further includes a gate insulating layer 7 provided between the semiconductor layer and the gate electrode. In the thin film transistor, current can flow between the source electrode and the drain electrode through the semiconductor layer in the vicinity of the gate insulating film so as to be controllable by the potential of the gate electrode. As the gate insulating film, various metal oxides, for example, oxides such as silicon, aluminum, tantalum, titanium, strontium, and barium, anodic oxide films of these metals, and mixed oxides of these oxides can be used. These thin films can be formed by a method such as sputtering or reactive vapor deposition. These thin films can also be formed by oxidizing the metal used for the gate electrode by a method such as atmospheric oxidation or anodic oxidation. As the gate insulating film, a polymer material such as a polymer material such as polystyrene, polyvinyl alcohol, polyvinyl phenol, or acrylic can be used. These thin films can be obtained by dissolving the material in an appropriate solvent and applying it. In particular, it is preferable to use an inorganic oxide such as SiO _x , SiN, or Y ₂ O ₃ as the gate insulating film. This is because these materials can be formed in the range of room temperature to 200 ° C. The patterning of the gate insulating layer can be easily performed by photolithography, similarly to the gate electrode. In particular, many metal oxides have a dielectric constant higher than that of a polymer material, and the transistor can be driven at a relatively low voltage. On the other hand, the polymer material has a characteristic that the high-speed response is good because the dielectric constant is relatively low. It is also possible to increase the effective dielectric constant of the thin film by dispersing oxide particles having a high dielectric constant in the polymer material. The thickness of the gate insulating film can be set to 100 nm, for example.

  The organic EL panel according to the present invention preferably further includes a source electrode 9 and a drain electrode 10 provided separately in electrical contact with the semiconductor layer. The metal is preferably gold. As described above, in addition to chemical stability, most of the organic electronic materials are hole transportable, and the work function of gold is as large as about 5.1 eV. It is because it is excellent. The thickness of the source electrode and the drain electrode can be set to 60 nm, for example. Moreover, the width | variety of a source electrode and a drain electrode can be 20 micrometers, respectively. The lengths of the source electrode and the drain electrode (corresponding to the channel width) can be 100 μm, respectively. Further, the width of the gap between the source electrode and the drain electrode (corresponding to the channel length) can be set to 10 μm. The source electrode and the drain electrode can be easily formed by sputtering or vacuum deposition of the target metal. The patterning of the source electrode and the drain electrode can be performed by a shadow mask or photolithography. In addition, it is preferable that a source electrode and / or a drain electrode contain a metal and a metal oxide. This is because metal oxides generally have high adhesion to the gate insulating film, and by incorporating these into a gold thin film, the adhesion between the source and drain electrodes and the gate insulating film is improved.

More specifically, for example, the thin film transistor can be provided as follows. First, MoCr (gate metal material) is deposited by sputtering, a resist is applied, and the resist is patterned using normal photolithography. After pattern formation, MoCr is etched with a commercially available Cr etching solution, and then the resist is peeled off. Thereafter, a SiN film is deposited by CVD as an insulating layer. Alternatively, Y ₂ O ₃ is deposited using sputtering or electron beam evaporation. (The gate insulating layer thickness is preferably 100 nm to 300 nm.) InZnGaO is deposited thereon by sputtering. The formation conditions are as described above. After depositing the InZnGaO thin film, a pattern is formed by photolithography and wet etching. Further, source and drain electrodes are formed of MoCr. As a formation method at this time, the gate electrode is formed by a similar method. Through the above steps, an InZnGaO TFT can be formed on the CCM substrate.

  The organic EL panel according to the present invention preferably further includes a passivation layer 11 between the thin film transistor and the organic EL element (described later). For the passivation layer, SiOx or SiN can be used.

  The organic EL panel according to the present invention preferably further includes a planarizing layer 12 between the thin film transistor and the organic EL element (described later). A novolac resin or an acrylic resin can be used for the planarizing layer.

The organic EL panel according to the present invention further includes organic EL elements 13 to 15 provided on the thin film transistor so as to be electrically controllable by the thin film transistor. More specifically, the organic EL element is
A first electrode 13 provided on the thin film transistor so as to be electrically controllable by the thin film transistor;
An organic EL layer 14 provided on the first electrode;
And a second electrode 15 provided on the organic EL layer. Note that each member (preferably including the first electrode, the organic EL layer, and the second electrode) included in the organic EL element is provided in a region (subpixel region) corresponding to the color modulation unit. preferable.

As described above, the organic EL panel according to the present invention preferably includes the first electrode 13 provided on the thin film transistor so as to be electrically controlled by the thin film transistor. For example, an opening 21 (contact hole) is provided in a layer (preferably a planarization layer) provided between the first electrode and the source or drain electrode, and the first electrode and the source electrode are passed through the opening. Alternatively, the drain electrode can be electrically connected, whereby the organic EL element can be electrically controlled by the thin film transistor. Preferably, the organic EL panel has a plurality of striped first electrodes extending in the first direction. The first electrode is preferably a transparent electrode, and specifically has a transmittance of preferably 50% or more, more preferably 85% or more with respect to light having a wavelength of 400 to 800 nm. As an example of the material of the first electrode, a conductive metal oxide such as SnO ₂ , In ₂ O ₃ , ITO, IZO, an alloy of ZnO and Al can be used. The thickness of the first electrode is usually 50 nm or more, preferably 50 nm to 1 μm, more preferably 100 to 500 nm. The first electrode can be formed by a known method such as sputtering.

  Moreover, it is preferable that the organic EL element concerning this invention further has an auxiliary electrode. The resistance of the first electrode can be suppressed by the auxiliary electrode. Examples of the material of the auxiliary electrode include metals such as Al, Mo, Ni, Cr, and W. The auxiliary electrode can be provided in either the display region or the region where a lead line to the external drive circuit of the first electrode is formed. For example, in the display area, it is arranged along the edge of the first electrode so as to be in contact with the first electrode in parallel with the first electrode so as not to prevent light emission from the organic light emitting layer. Can do. Further, the lead line forming region can be formed with the same width as the first electrode for the purpose of reducing the electric resistance of the first electrode. The thickness of the auxiliary electrode is usually 50 nm or more, preferably 50 nm to 1 μm.

The organic EL panel according to the present invention has an organic light emitting layer 14 provided on the first electrode. The organic EL panel can further have a hole injection layer, a hole transport layer, an electron transport layer, and / or an electron injection layer as necessary. Specifically, the organic light emitting device can have the above layers in the order shown below, for example. In the organic EL panel having the following laminated structure (1) to (7), the anode is electrically contacted with the organic light emitting layer or the hole injection layer, and the organic light emitting layer, electron transport layer or electron The cathode is in electrical contact with the injection layer.
(1) Organic light emitting layer (2) Hole injection layer / organic light emitting layer (3) Organic light emitting layer / electron injection layer (4) Hole injection layer / organic light emitting layer / electron injection layer (5) Hole transport layer / Organic light emitting layer / electron injection layer (6) Hole injection layer / hole transport layer / organic light emitting layer / electron injection layer (7) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer

Any known material can be used as the material of the organic light emitting layer. For example, in order to obtain light emission from blue to blue-green, for example, a condensed aromatic ring compound, a ring assembly compound, a metal complex (such as an aluminum complex such as Alq ₃ ), a styrylbenzene compound (4,4′-bis (diphenyl) (Vinyl) biphenyl (DPVBi) and the like), porphyrin compounds, benzothiazole compounds, benzimidazole compounds, benzoxazole compounds and the like, and materials such as aromatic dimethylidin compounds are preferably used. Or you may form the organic light emitting layer which emits the light of a various wavelength range by adding a dopant to a host compound. Examples of host compounds include distyrylarylene compounds (for example, IDE-120 manufactured by Idemitsu Kosan Co., Ltd.), N, N′-ditolyl-N, N′-diphenylbiphenylamine (TPD), aluminum tris (8-quinolinolate) (Alq ₃ ). ) Etc. can be used. As dopants, perylene (blue purple), coumarin 6 (blue), quinacridone compounds (blue green to green), rubrene (yellow), 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6-methyl- 4H-pyran (DCM, red), platinum octaethylporphyrin complex (PtOEP, red), or the like can be used.

  As the forest material for the hole injection layer, Pc (including CuPc) or indanthrene compounds can be used. The hole transport layer can be formed using a material having a triarylamine partial structure, a carbazole partial structure, or an oxadiazole partial structure. Materials that can be used preferably include TPD, [alpha] -NPD, MTDAPB (o-, m-, p-), m-MTDATA, and the like.

The material of the electron transport layer, aluminum complexes such as A1q _3; PBD, oxadiazole derivatives such as TPOB; thiophene derivatives such as BMB-2T; triazine derivatives; phenylquinoxalines such triazole derivatives such as TAZ Can be used. As the material for the electron injection layer, an aluminum complex such as Alq ₃ or an aluminum quinolinol complex doped with an alkali metal or an alkaline earth metal can be used.

  Optionally, an electron injecting material such as an alkali metal, an alkaline earth metal, an alloy containing them, or an alkali metal fluoride is provided at the interface between the organic light emitting layer (or electron transport layer or electron injection layer) and the cathode. By providing a buffer layer of a thin film (for example, a film thickness of 10 nm or less), the electron injection efficiency can be increased.

  The thicknesses of the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, and the electron injection layer should be appropriately set so as to be sufficient for realizing the desired characteristics in each. For example, it can be set to 100 nm, 20 nm, 30 nm, 20 nm, and 10 nm, respectively. In addition, the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, and the electron injection layer are formed by using any means known in the art such as vapor deposition (resistance heating or electron beam heating). can do.

  The organic EL panel according to the present invention has a second electrode 15 provided on the organic light emitting layer so as to face the first electrode. The organic EL panel preferably has a plurality of striped second electrodes extending in a second direction that intersects (preferably orthogonally) the first direction of the first electrode. In this manner, passive matrix driving can be performed by providing the first electrode and the second electrode that intersect in a matrix.

  The second electrode is preferably a reflective electrode, and is preferably formed using a highly reflective metal, amorphous alloy, or microcrystalline alloy. High reflectivity metals include Al, Ag, Mo, W, Ni, Cr, and the like. High reflectivity amorphous alloys include NiP, NiB, CrP, CrB, and the like. The highly reflective microcrystalline alloy includes NiAl and the like. The second electrode may be used as a cathode or an anode. When the second electrode is used as a cathode, the aforementioned buffer layer may be provided at the interface between the second electrode and the organic light emitting layer to improve the efficiency of electron injection into the organic light emitting layer.

  The second electrode can be formed using any means known in the art such as vapor deposition (resistance heating or electron beam heating), sputtering, ion plating, laser ablation, etc., depending on the material used. it can. A plurality of second electrodes may be formed using a mask that gives a desired shape, or a plurality of second electrodes may be formed using a separation partition wall having a reverse tapered cross-sectional shape. .

  The second electrode may have a stripe shape extending in the second direction. Here, the first direction relating to the first electrode and the second direction are preferably crossed, more preferably orthogonal. By adopting such a configuration, by applying an electric field to one of the first electrodes and one of the second electrodes, passive matrix driving for emitting light from the organic light-emitting layer at the intersection of the electrodes is performed. It can be carried out.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the examples described below.

  A color conversion substrate was prepared in the same manner as before. The color conversion substrate was produced by forming a color filter (red, blue, green) having a thickness of 1 μm on a glass substrate by photolithography. The pixel size was 1 mm square. On this, a red and green color conversion layer was formed to a thickness of about 3 μm. Thereafter, a planarizing layer was formed, and a SiN passivation layer was formed to 1 μm by a CVD method. In this example, a 5-inch organic EL panel was produced.

An IZO electrode (gate electrode) was formed on the color conversion substrate thus produced, and was patterned using a normal photolithography technique. Thereafter, Y ₂ O ₃ was formed as a gate insulating layer. After that, an oxide thin film was formed by a sputtering method using an In—Ga—Zn—O target (300 nm). Thereafter, patterning was performed to form a semiconductor layer. Thereafter, IZO electrodes (source electrode and drain electrode) were formed and patterned using a normal photolithography technique to form a thin film transistor on the passivation layer.

  Thereafter, a further flattening treatment was performed. As described above, the step of manufacturing the oxide thin film transistor (from the step of forming the semiconductor layer to the step of forming the planarization layer) was performed in an air atmosphere in a clean room.

  On top of this, an organic EL layer (hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer) is formed by a vapor deposition apparatus, and finally an Al electrode is formed to complete an organic EL element. It was.

  The organic EL panel was sealed in an inert atmosphere, and finally cut to obtain an organic EL panel according to this example.

  Efficiency was evaluated with respect to the organic electroluminescent panel concerning an Example. The efficiency of the organic EL panel was 2 cd / A, 4 cd / A, and 8 cd / A in red, blue, and green, respectively. These values are the same as those of conventional bottom emission type organic EL panels (that is, passive matrix type organic EL panels in which no TFT is provided between the color filter or the color conversion layer and the organic EL layer). . From this, it can be seen that there is no deterioration of the color filter or the color conversion layer by the TFT manufacturing process.

Furthermore, the driving life of the organic EL panel according to the example was evaluated. With the active matrix driving, the driving life at 100 cd / m ² was dramatically increased from 7000 hours to 20,000 hours or more.

  As described above, according to the present invention, it is possible to form an active matrix type organic EL panel capable of increasing the screen size without greatly changing from the conventional bottom emission type organic EL panel.

FIG. 1 shows a schematic cross-sectional view of an organic EL panel according to the present invention. In FIG. 2, the typical front view of the organic electroluminescent panel concerning this invention is shown. FIG. 3 is a schematic cross-sectional view of a conventional color conversion type active matrix organic EL panel.

Explanation of symbols

1: transparent substrate 2R, G, B: color filter layer 3R, G: color conversion layer 4: planarization layer 5: passivation layer 6: gate electrode 7: gate insulating layer 8: semiconductor layer 9: source electrode 10: drain electrode 11: Passivation layer 12: Planarization layer 13: First electrode 14: Organic EL layer 15: Second electrode 20: Subpixel region 21: Opening

Claims (14)

A transparent substrate;
A color modulation section provided on the transparent substrate;
A planarization layer provided on the color modulation unit;
A thin film transistor provided on the planarization layer;
An active matrix type organic EL panel comprising: an organic EL element provided on the thin film transistor so as to be electrically controllable by the thin film transistor. The thin film transistor is
A semiconductor layer;
A gate electrode;
A gate insulating layer provided between the semiconductor layer and the gate electrode;
The organic EL panel according to claim 1, further comprising: a source electrode and a drain electrode provided separately in electrical contact with the semiconductor layer.   The organic EL panel according to claim 2, wherein the semiconductor layer can be formed at room temperature.   The organic EL panel according to claim 2, wherein the semiconductor layer includes an organic semiconductor.   The organic EL panel according to claim 2, wherein the semiconductor layer includes an amorphous oxide semiconductor.   The organic EL panel according to claim 5, wherein the oxide semiconductor is an In—Zn—Ga—O based semiconductor. The organic EL element is
A first electrode provided on the thin film transistor so as to be electrically controllable by the thin film transistor;
An organic EL layer provided on the first electrode;
The organic EL panel according to claim 1, further comprising: a second electrode provided on the organic EL layer. A method for manufacturing an active matrix organic EL panel,
Providing a transparent substrate;
Providing a color modulator on the transparent substrate;
Providing a planarization layer on the color modulation unit;
Providing a thin film transistor on the planarizing layer;
Providing an organic EL element on the thin film transistor so as to be electrically controllable by the thin film transistor. Providing the thin film transistor comprises:
Providing a semiconductor layer;
Providing a gate electrode;
Providing a gate insulating layer between the step of providing the semiconductor layer and the step of providing the gate electrode;
And separately providing a source electrode and a drain electrode so as to be in electrical contact with the semiconductor layer.   The method of claim 9, wherein providing the semiconductor layer is performed at room temperature.   The method of claim 9 or 10, wherein the semiconductor layer comprises an organic semiconductor.   The method of claim 9 or 10, wherein the semiconductor layer comprises an amorphous oxide semiconductor.   The method according to claim 12, wherein the oxide semiconductor is an In—Zn—Ga—O based semiconductor. The step of providing the organic EL element comprises:
Providing a first electrode on the thin film transistor so as to be electrically controllable by the thin film transistor;
Providing an organic EL layer on the first electrode;
A method according to claim 8, further comprising: providing a second electrode on the organic EL layer.

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